Rachel Litke, MD, PhD

Study Overview

Objective. To update national trends in the treatment and risk factor control of diabetic patients from 1999 through 2018 in the US using data from the National Health and Nutrition Examination Survey (NHANES) with the goal of identifying population subgroups with the highest probability of having untreated risk factors.

Design. The authors conducted a cross-sectional analysis of data from NHANES focusing on adults with diabetes. They examined patient characteristics and medication use over time and estimated the prevalence of risk factor control and medication use. To minimize the effects of a small sample size, the survey years were pooled into 4-year intervals. The variables studied included glycated hemoglobin (HbA_1c), blood pressure, serum cholesterol, medication use, sociodemographic characteristics, and weight status. For statistical analysis, logistic and multinomial logistic regression models were used to examine factors associated with treatment in participants who did not achieve targets for glycemic, blood pressure, and lipid control. Temporal trends were estimated using 2-piece linear spline models with 1 knot at inflection points.

Setting and participants. The NHANES program began in the early 1960s to monitor the health of the US population. In 1999, the survey became a continuous program combining interviews and physical examinations. The survey examines a nationally representative sample of about 5000 persons each year. This study included 6653 participants who were nonpregnant, aged older than 20 years, reported a diagnosis of diabetes from a physician, and participated in NHANES from 1999 through 2018.

Main outcome measures. The main outcome measures were temporal trends in risk factor control (glycemic, blood pressure, or lipid levels) and medication use (glucose lowering, blood pressure lowering, or lipid lowering medications), and number as well as class of drug used, from 1999 through 2018 in diabetic adults from the US participating in NHANES.

Results. Sociodemographic characteristics of the studied diabetes population—The age and racial or ethnic distribution of participants with diabetes were stable from 1999 through 2018, whereas participants with a college degree, higher income, health insurance, obesity, or long-standing diabetes increased during the same period.

Trends in diabetes risk factor control—The trends for glycemic, blood pressure, and lipid control were nonlinear, with an inflection point around 2010. Glycemic control was defined as HbA_1c less than 7%, blood pressure was considered controlled if less than 140/90 mmHg, and lipid was controlled if non-HDL cholesterol level was less than 130 mg/dL. Although these chosen targets were based on the most recent clinical guidelines, the authors declared that they observed similar trends when alternative targets were used. The level of risk factor control improved in all diabetic patients from 1999 through 2010. However, the percentage of adult diabetic participants for whom glycemic control was achieved declined from 57.4% (95% CI, 52.9-61.8) in 2007-2010 to 50.5% (95% CI, 45.8-55.3) in 2015-2018. Blood pressure control was achieved in 74.2% of participants (95% CI, 70.7-77.4) in 2011-2014 but declined to 70.4% (95% CI, 66.7-73.8) in 2015-2018. Control in lipid levels improved during the entire study period; however, the rate of improvement heavily declined after 2007 with lipid target levels attained in 52.3% of participants (95% CI, 49.2-55.3) in 2007-2014 and 55.7% (95% CI, 50.8-60.5) in 2015-2018. Finally, the percentage of participants in whom targets for all 3 risk factors were simultaneously achieved plateaued after 2010 and was 22.2% (95% CI, 17.9-27.3) in 2015-2018.

Trends in diabetes treatment—The use of glucose lowering drugs increased from 74.1% in 1999-2002 to 82.7% in 2007-2010 and then stabilized. A shift toward a safer glucose lowering treatment choice was observed with a decline in the use of older glucose lowering medications such as sulfonylureas, which increases the risk of hypoglycemia, and an increase in the use of metformin, insulin, and newer agents such as sodium-glucose cotransporter 2 inhibitors.

Similarly, blood pressure lowering medication use rose from 1999-2002 to 2007-2010 and then stabilized, with increased use of first-line recommended treatments including angiotensin-converting enzyme inhibitors or angiotensin-receptor blockers. Likewise, statin use rose from 28.4% in 1999-2002 to 56% in 2011-2014 and then stabilized. The total number of drugs used culminated in 2011-2014 with 60% of participants using more than 5 drugs and then leveled off to 57.2% in 2015-2018. Lastly, health insurance status and race or ethnicity impacted the likelihood of receiving monotherapy or combination drug therapy when targets for glycemic, blood pressure, or lipid control were not achieved.

Conclusion. Despite great progress in the control of diabetes and its associated risk factors between 1999 and 2010, this trend declined for glycemic and blood pressure control and leveled off for lipid control in adult NHANES participants with diabetes after 2010. First-line treatments for diabetes and associated risk factors remain underused, and treatment intensification may not be sufficiently considered in patients with uncontrolled risk factors despite clinical guideline recommendations. The findings of this study may portend a possible population-level increase in diabetes-related illnesses in the years to come.

Commentary

The thorough understanding of trends in management of diseases is critical to inform public health policies and planning. Well designed clinical studies heavily influence the development of public health policies and clinical guidelines, which in turn drive real-world clinical practice. In a recent analysis utilizing data from NHANES, Fang et al¹ showed evidence of a general shift toward less intensive treatment of diabetes, hypertension, and hypercholesterolemia in adults living in the US during the last decade.

Similarly, in a separate study using NHANES data collected between 1999 and 2018 published in JAMA just 2 weeks after the current report, Wang et al² confirms this declining trend in diabetes management with only 21.2% of diabetic adults simultaneously attaining glycemic, blood pressure, and lipid level targets during the same period. What led to the decline in more stringent risk factor and diabetes management since 2010 observed in these studies? One possible explanation, as suggested by Fang et al, is that major clinical trials from the late 2000s­—including Action to Control Cardiovascular Risk in Diabetes, UK Prospective Diabetes Study, Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation, and Veterans Affairs Diabetes Trial—that assessed the effects of intensive glycemic control (with target HbA_1c < 6.5%) found that intensive treatment of diabetes compared to standard care had no cardiovascular benefit albeit increasing the risk of hypoglycemia. Thus, these trial findings may have translated into suboptimal diabetes treatment observed in some NHANES participants. Wang et al propose that effective tailored approaches are needed to improve risk factor control in diabetic patients, such as enhance and maintain adherence to medications and healthy lifestyle behaviors, as well as better access to health care and therapeutic education.

The changes in recent trends in diabetes management have immense clinical implications. The authors of this study suggest a link between the recent relaxation of glycemic targets, as well as risk factor control, and a resurgence of diabetic complications such as lower limb amputation or stroke. Indeed, several recent studies indicate an upward trend or plateau in diabetic complications which had been decreasing in prevalence prior to 2010.³ For example, lower extremity amputation has surged by more than 25% between 2010 and 2015, especially in young and middle-aged adults.⁴ Among the arguments brought forward that this recent resurgence in amputations is directly linked to worsening glycemic control is the fact that between 2007 and 2010, when glucose levels were best controlled within the previous 30-year period, amputations were also at the lowest levels. Moreover, data from the Centers for Disease Control and Prevention also show a 55% increase in mortality (from 15.7 to 24.2 per 1000) among diabetic patients between 2010 and 2015.¹⁴ On the other hand, a growing number of studies show that an increase of inappropriate treatment intensification—reaching HbA_1c levels that are way below the recommended targets—is associated with adverse consequences in diabetic patients particularly in those aged more than 65 years.^5-7 These seemingly contradictory findings highlight the importance of a personalized and thoughtful approach to the management of diabetes and its risk factors. As an example, an increase in the use of newer and safer glucose lowering drugs (eg, sodium-glucose cotransporter 2 inhibitors, glucagon-like peptide 1 receptor agonists, and dipeptidyl peptidase 4 inhibitors) can help achieve better HbA_1c goals with a reduced risk of hypoglycemic episodes as recently shown by a Danish study.⁸ In this study, the authors concluded that the reduction of the rate of hypoglycemic episodes leading to hospitalization in Denmark was directly linked to the use of these safer and newer glucose lowering drugs.

A discussion on the specifics of trends in diabetes treatment and control must include considerations in older adults aged more than 65 years who constitute more than 40% of the diabetic population. Despite the high prevalence of diabetes in this vulnerable population, such data are still insufficient in the literature and are critically needed to inform public health policies and clinical guidelines. In epidemiological studies focusing on diabetic complications from the last 10 years, concerning increases have been observed in younger⁹ and middle-aged adults while remaining stable in older adults. However, the risk of hypoglycemia or severe hypoglycemia remains high in older adults living in nursing facilities, even in those with an elevated HbA_1c of greater than 8%.⁷ Moreover, in light of more relaxed HbA_1c treatment goals for older frail adults as recommended by international guidelines since 2010,^10,11 recent findings from the French GERODIAB cohort show an increased mortality (hazard ratio, 1.76) in type 2 diabetics aged 70 years and older with HbA_1c greater than or equal to 8.6%.¹² Similarly, a 5-year retrospective British study from 2018 which included patients aged 70 years and older, shows an increased overall mortality in those with HbA_1c greater than 8.5%.¹³ Taken together, further age-stratified analysis utilizing data from large cohort studies including NHANES may help to clarify national trends in diabetes treatment and risk factor control as well as diabetic complications specific to the geriatric population. By being better informed of such trends, clinicians could then develop treatment strategies that minimize complications (eg, hypoglycemia, falls) while achieving favorable outcomes (eg, reduce hyperglycemic emergencies, improve survival) in frail older patients.

Applications for Clinical Practice

The understanding of population-wide trends in diabetes control is critical to planning public health approaches for the prevention and treatment of this disease and its complications. In older adults, the high risk of hypoglycemic events and insufficient epidemiological data on trends of diabetes control hinder diabetes management. Personalized treatment targets taking into account geriatric syndromes and general health status, as well as multidisciplinary management involving endocrinologists, geriatricians, and clinical pharmacists, are necessary to optimize care in older adults with diabetes.

Study Overview

Objective. To update national trends in the treatment and risk factor control of diabetic patients from 1999 through 2018 in the US using data from the National Health and Nutrition Examination Survey (NHANES) with the goal of identifying population subgroups with the highest probability of having untreated risk factors.

Design. The authors conducted a cross-sectional analysis of data from NHANES focusing on adults with diabetes. They examined patient characteristics and medication use over time and estimated the prevalence of risk factor control and medication use. To minimize the effects of a small sample size, the survey years were pooled into 4-year intervals. The variables studied included glycated hemoglobin (HbA_1c), blood pressure, serum cholesterol, medication use, sociodemographic characteristics, and weight status. For statistical analysis, logistic and multinomial logistic regression models were used to examine factors associated with treatment in participants who did not achieve targets for glycemic, blood pressure, and lipid control. Temporal trends were estimated using 2-piece linear spline models with 1 knot at inflection points.

Setting and participants. The NHANES program began in the early 1960s to monitor the health of the US population. In 1999, the survey became a continuous program combining interviews and physical examinations. The survey examines a nationally representative sample of about 5000 persons each year. This study included 6653 participants who were nonpregnant, aged older than 20 years, reported a diagnosis of diabetes from a physician, and participated in NHANES from 1999 through 2018.

Main outcome measures. The main outcome measures were temporal trends in risk factor control (glycemic, blood pressure, or lipid levels) and medication use (glucose lowering, blood pressure lowering, or lipid lowering medications), and number as well as class of drug used, from 1999 through 2018 in diabetic adults from the US participating in NHANES.

Results. Sociodemographic characteristics of the studied diabetes population—The age and racial or ethnic distribution of participants with diabetes were stable from 1999 through 2018, whereas participants with a college degree, higher income, health insurance, obesity, or long-standing diabetes increased during the same period.

Trends in diabetes risk factor control—The trends for glycemic, blood pressure, and lipid control were nonlinear, with an inflection point around 2010. Glycemic control was defined as HbA_1c less than 7%, blood pressure was considered controlled if less than 140/90 mmHg, and lipid was controlled if non-HDL cholesterol level was less than 130 mg/dL. Although these chosen targets were based on the most recent clinical guidelines, the authors declared that they observed similar trends when alternative targets were used. The level of risk factor control improved in all diabetic patients from 1999 through 2010. However, the percentage of adult diabetic participants for whom glycemic control was achieved declined from 57.4% (95% CI, 52.9-61.8) in 2007-2010 to 50.5% (95% CI, 45.8-55.3) in 2015-2018. Blood pressure control was achieved in 74.2% of participants (95% CI, 70.7-77.4) in 2011-2014 but declined to 70.4% (95% CI, 66.7-73.8) in 2015-2018. Control in lipid levels improved during the entire study period; however, the rate of improvement heavily declined after 2007 with lipid target levels attained in 52.3% of participants (95% CI, 49.2-55.3) in 2007-2014 and 55.7% (95% CI, 50.8-60.5) in 2015-2018. Finally, the percentage of participants in whom targets for all 3 risk factors were simultaneously achieved plateaued after 2010 and was 22.2% (95% CI, 17.9-27.3) in 2015-2018.

Trends in diabetes treatment—The use of glucose lowering drugs increased from 74.1% in 1999-2002 to 82.7% in 2007-2010 and then stabilized. A shift toward a safer glucose lowering treatment choice was observed with a decline in the use of older glucose lowering medications such as sulfonylureas, which increases the risk of hypoglycemia, and an increase in the use of metformin, insulin, and newer agents such as sodium-glucose cotransporter 2 inhibitors.

Similarly, blood pressure lowering medication use rose from 1999-2002 to 2007-2010 and then stabilized, with increased use of first-line recommended treatments including angiotensin-converting enzyme inhibitors or angiotensin-receptor blockers. Likewise, statin use rose from 28.4% in 1999-2002 to 56% in 2011-2014 and then stabilized. The total number of drugs used culminated in 2011-2014 with 60% of participants using more than 5 drugs and then leveled off to 57.2% in 2015-2018. Lastly, health insurance status and race or ethnicity impacted the likelihood of receiving monotherapy or combination drug therapy when targets for glycemic, blood pressure, or lipid control were not achieved.

Conclusion. Despite great progress in the control of diabetes and its associated risk factors between 1999 and 2010, this trend declined for glycemic and blood pressure control and leveled off for lipid control in adult NHANES participants with diabetes after 2010. First-line treatments for diabetes and associated risk factors remain underused, and treatment intensification may not be sufficiently considered in patients with uncontrolled risk factors despite clinical guideline recommendations. The findings of this study may portend a possible population-level increase in diabetes-related illnesses in the years to come.

Commentary

The thorough understanding of trends in management of diseases is critical to inform public health policies and planning. Well designed clinical studies heavily influence the development of public health policies and clinical guidelines, which in turn drive real-world clinical practice. In a recent analysis utilizing data from NHANES, Fang et al¹ showed evidence of a general shift toward less intensive treatment of diabetes, hypertension, and hypercholesterolemia in adults living in the US during the last decade.

Similarly, in a separate study using NHANES data collected between 1999 and 2018 published in JAMA just 2 weeks after the current report, Wang et al² confirms this declining trend in diabetes management with only 21.2% of diabetic adults simultaneously attaining glycemic, blood pressure, and lipid level targets during the same period. What led to the decline in more stringent risk factor and diabetes management since 2010 observed in these studies? One possible explanation, as suggested by Fang et al, is that major clinical trials from the late 2000s­—including Action to Control Cardiovascular Risk in Diabetes, UK Prospective Diabetes Study, Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation, and Veterans Affairs Diabetes Trial—that assessed the effects of intensive glycemic control (with target HbA_1c < 6.5%) found that intensive treatment of diabetes compared to standard care had no cardiovascular benefit albeit increasing the risk of hypoglycemia. Thus, these trial findings may have translated into suboptimal diabetes treatment observed in some NHANES participants. Wang et al propose that effective tailored approaches are needed to improve risk factor control in diabetic patients, such as enhance and maintain adherence to medications and healthy lifestyle behaviors, as well as better access to health care and therapeutic education.

The changes in recent trends in diabetes management have immense clinical implications. The authors of this study suggest a link between the recent relaxation of glycemic targets, as well as risk factor control, and a resurgence of diabetic complications such as lower limb amputation or stroke. Indeed, several recent studies indicate an upward trend or plateau in diabetic complications which had been decreasing in prevalence prior to 2010.³ For example, lower extremity amputation has surged by more than 25% between 2010 and 2015, especially in young and middle-aged adults.⁴ Among the arguments brought forward that this recent resurgence in amputations is directly linked to worsening glycemic control is the fact that between 2007 and 2010, when glucose levels were best controlled within the previous 30-year period, amputations were also at the lowest levels. Moreover, data from the Centers for Disease Control and Prevention also show a 55% increase in mortality (from 15.7 to 24.2 per 1000) among diabetic patients between 2010 and 2015.¹⁴ On the other hand, a growing number of studies show that an increase of inappropriate treatment intensification—reaching HbA_1c levels that are way below the recommended targets—is associated with adverse consequences in diabetic patients particularly in those aged more than 65 years.^5-7 These seemingly contradictory findings highlight the importance of a personalized and thoughtful approach to the management of diabetes and its risk factors. As an example, an increase in the use of newer and safer glucose lowering drugs (eg, sodium-glucose cotransporter 2 inhibitors, glucagon-like peptide 1 receptor agonists, and dipeptidyl peptidase 4 inhibitors) can help achieve better HbA_1c goals with a reduced risk of hypoglycemic episodes as recently shown by a Danish study.⁸ In this study, the authors concluded that the reduction of the rate of hypoglycemic episodes leading to hospitalization in Denmark was directly linked to the use of these safer and newer glucose lowering drugs.

A discussion on the specifics of trends in diabetes treatment and control must include considerations in older adults aged more than 65 years who constitute more than 40% of the diabetic population. Despite the high prevalence of diabetes in this vulnerable population, such data are still insufficient in the literature and are critically needed to inform public health policies and clinical guidelines. In epidemiological studies focusing on diabetic complications from the last 10 years, concerning increases have been observed in younger⁹ and middle-aged adults while remaining stable in older adults. However, the risk of hypoglycemia or severe hypoglycemia remains high in older adults living in nursing facilities, even in those with an elevated HbA_1c of greater than 8%.⁷ Moreover, in light of more relaxed HbA_1c treatment goals for older frail adults as recommended by international guidelines since 2010,^10,11 recent findings from the French GERODIAB cohort show an increased mortality (hazard ratio, 1.76) in type 2 diabetics aged 70 years and older with HbA_1c greater than or equal to 8.6%.¹² Similarly, a 5-year retrospective British study from 2018 which included patients aged 70 years and older, shows an increased overall mortality in those with HbA_1c greater than 8.5%.¹³ Taken together, further age-stratified analysis utilizing data from large cohort studies including NHANES may help to clarify national trends in diabetes treatment and risk factor control as well as diabetic complications specific to the geriatric population. By being better informed of such trends, clinicians could then develop treatment strategies that minimize complications (eg, hypoglycemia, falls) while achieving favorable outcomes (eg, reduce hyperglycemic emergencies, improve survival) in frail older patients.

Applications for Clinical Practice

The understanding of population-wide trends in diabetes control is critical to planning public health approaches for the prevention and treatment of this disease and its complications. In older adults, the high risk of hypoglycemic events and insufficient epidemiological data on trends of diabetes control hinder diabetes management. Personalized treatment targets taking into account geriatric syndromes and general health status, as well as multidisciplinary management involving endocrinologists, geriatricians, and clinical pharmacists, are necessary to optimize care in older adults with diabetes.

Study Overview

Objective. To update national trends in the treatment and risk factor control of diabetic patients from 1999 through 2018 in the US using data from the National Health and Nutrition Examination Survey (NHANES) with the goal of identifying population subgroups with the highest probability of having untreated risk factors.

Design. The authors conducted a cross-sectional analysis of data from NHANES focusing on adults with diabetes. They examined patient characteristics and medication use over time and estimated the prevalence of risk factor control and medication use. To minimize the effects of a small sample size, the survey years were pooled into 4-year intervals. The variables studied included glycated hemoglobin (HbA_1c), blood pressure, serum cholesterol, medication use, sociodemographic characteristics, and weight status. For statistical analysis, logistic and multinomial logistic regression models were used to examine factors associated with treatment in participants who did not achieve targets for glycemic, blood pressure, and lipid control. Temporal trends were estimated using 2-piece linear spline models with 1 knot at inflection points.

Setting and participants. The NHANES program began in the early 1960s to monitor the health of the US population. In 1999, the survey became a continuous program combining interviews and physical examinations. The survey examines a nationally representative sample of about 5000 persons each year. This study included 6653 participants who were nonpregnant, aged older than 20 years, reported a diagnosis of diabetes from a physician, and participated in NHANES from 1999 through 2018.

Main outcome measures. The main outcome measures were temporal trends in risk factor control (glycemic, blood pressure, or lipid levels) and medication use (glucose lowering, blood pressure lowering, or lipid lowering medications), and number as well as class of drug used, from 1999 through 2018 in diabetic adults from the US participating in NHANES.

Results. Sociodemographic characteristics of the studied diabetes population—The age and racial or ethnic distribution of participants with diabetes were stable from 1999 through 2018, whereas participants with a college degree, higher income, health insurance, obesity, or long-standing diabetes increased during the same period.

Trends in diabetes risk factor control—The trends for glycemic, blood pressure, and lipid control were nonlinear, with an inflection point around 2010. Glycemic control was defined as HbA_1c less than 7%, blood pressure was considered controlled if less than 140/90 mmHg, and lipid was controlled if non-HDL cholesterol level was less than 130 mg/dL. Although these chosen targets were based on the most recent clinical guidelines, the authors declared that they observed similar trends when alternative targets were used. The level of risk factor control improved in all diabetic patients from 1999 through 2010. However, the percentage of adult diabetic participants for whom glycemic control was achieved declined from 57.4% (95% CI, 52.9-61.8) in 2007-2010 to 50.5% (95% CI, 45.8-55.3) in 2015-2018. Blood pressure control was achieved in 74.2% of participants (95% CI, 70.7-77.4) in 2011-2014 but declined to 70.4% (95% CI, 66.7-73.8) in 2015-2018. Control in lipid levels improved during the entire study period; however, the rate of improvement heavily declined after 2007 with lipid target levels attained in 52.3% of participants (95% CI, 49.2-55.3) in 2007-2014 and 55.7% (95% CI, 50.8-60.5) in 2015-2018. Finally, the percentage of participants in whom targets for all 3 risk factors were simultaneously achieved plateaued after 2010 and was 22.2% (95% CI, 17.9-27.3) in 2015-2018.

Trends in diabetes treatment—The use of glucose lowering drugs increased from 74.1% in 1999-2002 to 82.7% in 2007-2010 and then stabilized. A shift toward a safer glucose lowering treatment choice was observed with a decline in the use of older glucose lowering medications such as sulfonylureas, which increases the risk of hypoglycemia, and an increase in the use of metformin, insulin, and newer agents such as sodium-glucose cotransporter 2 inhibitors.

Similarly, blood pressure lowering medication use rose from 1999-2002 to 2007-2010 and then stabilized, with increased use of first-line recommended treatments including angiotensin-converting enzyme inhibitors or angiotensin-receptor blockers. Likewise, statin use rose from 28.4% in 1999-2002 to 56% in 2011-2014 and then stabilized. The total number of drugs used culminated in 2011-2014 with 60% of participants using more than 5 drugs and then leveled off to 57.2% in 2015-2018. Lastly, health insurance status and race or ethnicity impacted the likelihood of receiving monotherapy or combination drug therapy when targets for glycemic, blood pressure, or lipid control were not achieved.

Conclusion. Despite great progress in the control of diabetes and its associated risk factors between 1999 and 2010, this trend declined for glycemic and blood pressure control and leveled off for lipid control in adult NHANES participants with diabetes after 2010. First-line treatments for diabetes and associated risk factors remain underused, and treatment intensification may not be sufficiently considered in patients with uncontrolled risk factors despite clinical guideline recommendations. The findings of this study may portend a possible population-level increase in diabetes-related illnesses in the years to come.

Commentary

The thorough understanding of trends in management of diseases is critical to inform public health policies and planning. Well designed clinical studies heavily influence the development of public health policies and clinical guidelines, which in turn drive real-world clinical practice. In a recent analysis utilizing data from NHANES, Fang et al¹ showed evidence of a general shift toward less intensive treatment of diabetes, hypertension, and hypercholesterolemia in adults living in the US during the last decade.

Similarly, in a separate study using NHANES data collected between 1999 and 2018 published in JAMA just 2 weeks after the current report, Wang et al² confirms this declining trend in diabetes management with only 21.2% of diabetic adults simultaneously attaining glycemic, blood pressure, and lipid level targets during the same period. What led to the decline in more stringent risk factor and diabetes management since 2010 observed in these studies? One possible explanation, as suggested by Fang et al, is that major clinical trials from the late 2000s­—including Action to Control Cardiovascular Risk in Diabetes, UK Prospective Diabetes Study, Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation, and Veterans Affairs Diabetes Trial—that assessed the effects of intensive glycemic control (with target HbA_1c < 6.5%) found that intensive treatment of diabetes compared to standard care had no cardiovascular benefit albeit increasing the risk of hypoglycemia. Thus, these trial findings may have translated into suboptimal diabetes treatment observed in some NHANES participants. Wang et al propose that effective tailored approaches are needed to improve risk factor control in diabetic patients, such as enhance and maintain adherence to medications and healthy lifestyle behaviors, as well as better access to health care and therapeutic education.

The changes in recent trends in diabetes management have immense clinical implications. The authors of this study suggest a link between the recent relaxation of glycemic targets, as well as risk factor control, and a resurgence of diabetic complications such as lower limb amputation or stroke. Indeed, several recent studies indicate an upward trend or plateau in diabetic complications which had been decreasing in prevalence prior to 2010.³ For example, lower extremity amputation has surged by more than 25% between 2010 and 2015, especially in young and middle-aged adults.⁴ Among the arguments brought forward that this recent resurgence in amputations is directly linked to worsening glycemic control is the fact that between 2007 and 2010, when glucose levels were best controlled within the previous 30-year period, amputations were also at the lowest levels. Moreover, data from the Centers for Disease Control and Prevention also show a 55% increase in mortality (from 15.7 to 24.2 per 1000) among diabetic patients between 2010 and 2015.¹⁴ On the other hand, a growing number of studies show that an increase of inappropriate treatment intensification—reaching HbA_1c levels that are way below the recommended targets—is associated with adverse consequences in diabetic patients particularly in those aged more than 65 years.^5-7 These seemingly contradictory findings highlight the importance of a personalized and thoughtful approach to the management of diabetes and its risk factors. As an example, an increase in the use of newer and safer glucose lowering drugs (eg, sodium-glucose cotransporter 2 inhibitors, glucagon-like peptide 1 receptor agonists, and dipeptidyl peptidase 4 inhibitors) can help achieve better HbA_1c goals with a reduced risk of hypoglycemic episodes as recently shown by a Danish study.⁸ In this study, the authors concluded that the reduction of the rate of hypoglycemic episodes leading to hospitalization in Denmark was directly linked to the use of these safer and newer glucose lowering drugs.

A discussion on the specifics of trends in diabetes treatment and control must include considerations in older adults aged more than 65 years who constitute more than 40% of the diabetic population. Despite the high prevalence of diabetes in this vulnerable population, such data are still insufficient in the literature and are critically needed to inform public health policies and clinical guidelines. In epidemiological studies focusing on diabetic complications from the last 10 years, concerning increases have been observed in younger⁹ and middle-aged adults while remaining stable in older adults. However, the risk of hypoglycemia or severe hypoglycemia remains high in older adults living in nursing facilities, even in those with an elevated HbA_1c of greater than 8%.⁷ Moreover, in light of more relaxed HbA_1c treatment goals for older frail adults as recommended by international guidelines since 2010,^10,11 recent findings from the French GERODIAB cohort show an increased mortality (hazard ratio, 1.76) in type 2 diabetics aged 70 years and older with HbA_1c greater than or equal to 8.6%.¹² Similarly, a 5-year retrospective British study from 2018 which included patients aged 70 years and older, shows an increased overall mortality in those with HbA_1c greater than 8.5%.¹³ Taken together, further age-stratified analysis utilizing data from large cohort studies including NHANES may help to clarify national trends in diabetes treatment and risk factor control as well as diabetic complications specific to the geriatric population. By being better informed of such trends, clinicians could then develop treatment strategies that minimize complications (eg, hypoglycemia, falls) while achieving favorable outcomes (eg, reduce hyperglycemic emergencies, improve survival) in frail older patients.

Applications for Clinical Practice

The understanding of population-wide trends in diabetes control is critical to planning public health approaches for the prevention and treatment of this disease and its complications. In older adults, the high risk of hypoglycemic events and insufficient epidemiological data on trends of diabetes control hinder diabetes management. Personalized treatment targets taking into account geriatric syndromes and general health status, as well as multidisciplinary management involving endocrinologists, geriatricians, and clinical pharmacists, are necessary to optimize care in older adults with diabetes.

Study Overview

Objective. To assess whether dapagliflozin added to guideline-recommended therapies is effective and safe over the long-term to reduce the rate of renal and cardiovascular events in patients across multiple chronic kidney disease (CKD) stages, with and without type 2 diabetes.

Design. The Dapagliflozin and Prevention of Adverse Outcomes in CKD (DAPA-CKD) trial (NCT03036150) was a randomized, double-blind, parallel-group, placebo-controlled, multicenter event-driven, clinical trial sponsored by Astra-Zeneca. It was conducted at 386 sites in 21 countries from February 2, 2017, to June 12, 2020. A recruitment period of 24 months and a total study duration of 45 months were initially planned. The primary efficacy analysis was based on the intention-to-treat population. This was the first randomized controlled trial designed to assess the effects of sodium-glucose co-transporter 2 (SGLT2) inhibitors on renal and cardiovascular outcomes in patients with CKD.

Setting and participants. This trial randomly assigned 4304 adult participants with CKD stages 2 to 4 (an estimated glomerular filtration rate [GFR] of 25 to 75 mL/min/1.73 m² of body-surface area) and elevated urinary albumin excretion (urinary albumin-to-creatinine ratio of 200 to 5000, measured in mg of albumin per g of creatinine) to receive dapagliflozin (10 mg once daily) or placebo. Exclusion criteria included type 1 diabetes, polycystic kidney disease, lupus nephritis, antineutrophil cytoplasmic antibody–associated vasculitis, recent immunosuppressive therapy for primary or secondary kidney disease, New York Heart Association class IV congestive heart failure, myocardial infarction, unstable angina, stroke or transient ischemic attacks, or recent coronary revascularization or valvular repair/replacement. All participants received a stable dose of renin–angiotensin system inhibitor for 4 weeks prior to screening, and the vast majority received a maximum tolerated dose at enrollment. Randomization was monitored to ensure that at least 30% of participants recruited did not have diabetes and that no more than 10% had stage 2 CKD. Participants were randomly assigned to receive dapagliflozin (n = 2152) or matching placebo (n = 2152) to ensure a 1:1 ratio of the 2 regimens. Dapagliflozin and placebo had identical appearance and administration schedules. All participants and trial personnel (except members of the independent data monitoring committee) were unaware of the trial-group assignments. After randomization, in-person study visits were conducted at 2 weeks, at 2, 4, and 8 months, and at 4-month intervals thereafter.

Main outcome measures. The primary outcome was a composite of the first occurrence of either a sustained decline in the estimated GFR of at least 50%, end-stage kidney disease, or death from renal or cardiovascular causes. Secondary outcomes, in hierarchical order, were: (1) the composite kidney outcome of a sustained decline in the estimated GFR of at least 50%, end-stage kidney disease, or death from renal causes; (2) a composite cardiovascular outcome defined as hospitalization for heart failure or death from cardiovascular causes; and (3) death from any cause. All outcomes were assessed by time-to-event analyses.

Given the extensive prior experience with dapagliflozin, only selected adverse events were recorded. These included serious adverse events, adverse events resulting in the discontinuation of dapagliflozin or placebo, and adverse events of interest to dapagliflozin (eg, volume depletion symptoms, renal events, major hypoglycemia, fractures, diabetic ketoacidosis, events leading to higher risk of lower limb amputation, and lower limb amputations).

Main results. On March 26, 2020, the independent data monitoring committee recommended stopping the trial because of clear efficacy on the basis of 408 primary outcome events. The participants were 61.8 ± 12.1 years of age, and 1425 participants (33.1%) were female. The baseline mean estimated GFR was 43.1 ± 12.4 mL/min/1.73 m², the median urinary albumin-to-creatinine ratio was 949, and 2906 participants (67.5%) had type 2 diabetes. Over a median of 2.4 years, a primary outcome event occurred in 197 participants (9.2%) in the dapagliflozin group and 312 (14.5%) in the placebo group (hazard ratio [HR], 0.61; 95% confidence interval [CI], 0.51-0.72; P < 0.001). The number of participants who needed to be treated during the trial period to prevent 1 primary outcome event was 19 (95% CI, 15-27). The beneficial effect of dapagliflozin compared with placebo was consistent across all 8 prespecified subgroups (ie, age, sex, race, geographic region, type 2 diabetes, estimated GFR, urinary albumin-to-creatinine ratio, and systolic blood pressure) for the primary outcome. The effects of dapagliflozin were similar in participants with type 2 diabetes and in those without type 2 diabetes.

The incidence of each secondary outcome was similarly lower in the dapagliflozin-treated group than in the placebo group. The HR for the composite kidney outcome of a sustained decline in the estimated GFR of at least 50%, end-stage kidney disease, or death from renal causes was 0.56 (95% CI, 0.45-0.68; P < 0.001), and the HR for the composite cardiovascular outcome of hospitalization for heart failure or death from cardiovascular causes was 0.71 (95% CI, 0.55-0.92; P = 0.009). Death occurred in 101 participants (4.7%) in the dapagliflozin group and 146 participants (6.8%) in the placebo group (HR, 0.69; 95% CI, 0.53-0.88; P = 0.004). The known safety profile of dapagliflozin was confirmed by the similar overall incidences of adverse events and serious adverse events in the dapagliflozin and placebo groups.

Conclusion. In patients with CKD, with or without type 2 diabetes, the risk of a composite of a sustained decline in the estimated GFR of at least 50%, end-stage kidney disease, or death from renal or cardiovascular causes was significantly lowered by dapagliflozin treatment.

Commentary

Although SGLT2 inhibitors were designed to reduce plasma glucose and hemoglobin A1c (HbA1c) by increasing urinary glucose excretion in a non-insulin-dependent fashion, an increasing number of clinical trials have demonstrated their possible cardiovascular and renal benefits that extend beyond glycemic control. In 2008, the US Food and Drug Administration (FDA) issued a guidance recommending the evaluation of long-term cardiovascular outcomes prior to approval and commercialization of new antidiabetic therapies to ensure minimum cardiovascular risks following the discovery of cardiovascular safety issues associated with antidiabetic compounds, including rosiglitazone, after drug approval. No one foresaw that this recommendation would lead to the discovery of new classes of antidiabetic drugs (glucagon-like peptide 1 [GLP1] and SGLT2 inhibitors) that improve cardiovascular outcomes. A series of clinical trials of SGLT2 inhibitors, including empagliflozin,¹ canagliflozin,² and dapagliflozin,³ showed a reduction in cardiovascular death and hospitalization due to heart failure among patients with type 2 diabetes. Furthermore, a meta-analysis from 2019 found that SGLT2 inhibitors reduced the risk of a composite of cardiovascular death or hospitalization for heart failure by 23% and the risk of progression of kidney failure by 45% in patients with diabetes.⁴ Thus, the strong and consistent evidence from these large and well-designed outcome trials led the American Diabetes Association in its most recent guidelines to recommend adding SGLT2 inhibitors to metformin for the treatment of patients with type 2 diabetes with or at high risk of atherosclerotic cardiovascular disease, heart failure, or CKD, regardless of baseline HbA1c levels or HbA1c target.⁵ As a result of the compelling effects of SGLT2 inhibitors on cardiovascular outcomes in diabetic patients, as well as increasing evidence that these clinical effects were independent of glycemic control, several subsequent trials were conducted to evaluate whether this new class of drugs may improve clinical outcomes in nondiabetic patients.

The Dapagliflozin and Prevention of Adverse Outcomes in Heart Failure (DAPA-HF) was the first clinical trial to investigate the effect of SGLT2 inhibitors on cardiovascular disease in nondiabetic patients. Findings from DAPA-HF showed that dapagliflozin reduced the risk of worsening heart failure or death from cardiovascular causes, independent of the presence of underlying diabetes. This initial finding resonates with a growing body of evidence^6,7 that supports the use of SGLT2 inhibitors as an adjunctive therapy for heart failure in the absence of diabetes.

The Canagliflozin and Renal Events in Diabetes with Established Nephropathy Clinical Evaluation (CREDENCE) trial showed that long-term administration of canagliflozin conferred cardiovascular, as well as renal, protection in patients with type 2 diabetes with CKD.⁸ Similar to the protective effects on heart failure, the renal benefits of SGLT2 inhibitors appeared to be independent of their blood glucose-lowering effects. Thus, these recent discoveries led to the design of the DAPA-CKD trial to further assess the long-term efficacy and safety of the SGLT2 inhibitor dapagliflozin in patients with CKD precipitated by causes other than type 2 diabetes. Although diabetes is the most common cause for CKD, it nonetheless only accounts for 40% of all CKD etiologies. To date, the only classes of medication that have been shown to slow a decline in kidney function in patients with diabetes are angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs). Given that CKD is an important contributor to illness, is associated with diminished quality of life and reduced life expectancy, and increases health care costs, the findings of the DAPA-CKD trial are particularly significant as they show a renal benefit of dapagliflozin treatment across CKD stages that is independent of underlying diabetes. Therefore, SGLT2 inhibitors may offer a new and unique treatment option for millions of patients with CKD worldwide for whom ACE inhibitors and ARBs were otherwise the only treatments to prevent kidney failure. Moreover, with a number-needed-to-treat of 19 to prevent 1 composite renal vascular event over a period of 2.4 years, dapagliflozin requires a much lower number needed to treat compared to ACE inhibitors and ARBs in similar patients.

The trial has several limitations in study design. For example, the management of diabetes and hypertension were left to the discretion of each trial site, in keeping with local clinical practice and guidelines. It is unknown whether this variability in the management of comorbidities that impact kidney function had an effect on the study’s results. In addition, the trial was stopped early as a result of recommendations from an independent committee due to the demonstrated efficacy of dapagliflozin. This may have reduced the statistical power to assess some of the secondary outcomes. Finally, the authors discussed an initial dip in the estimated GFR after initiation of dapagliflozin treatment, similar to that observed in other SGLT2 inhibitor clinical trials. However, they were unable to ascertain the reversibility of this effect after the discontinuation of dapagliflozin because assessment of GFR was not completed after trial closure. Nonetheless, the authors specified that the reversibility of this initial estimated GFR dip had been assessed and observed in other clinical trials involving dapagliflozin.

The nonglycemic benefits of SGLT2 inhibitors, including improvement in renal outcomes, have strong implications for the future management of patients with CKD. If this indication is approved by the FDA and recommended by clinical guidelines, the ease of SGLT2 inhibitor prescription (eg, minimal drug-drug interaction, no titration), treatment administration (orally once daily), and safety profile may lead to wide use of SGLT2 inhibitors by generalists, nephrologists, and endocrinologists in preserving or improving renal outcomes in patients at risk for end-stage kidney disease. Given that SGLT2 inhibitors are a new class of pharmacologic therapeutics, patient education should include a discussion of the possible side effects, such as euglycemic ketoacidosis, genital and urinary tract infection, and foot and leg amputation. Finally, as Strandberg and colleagues reported in a recent commentary,⁹ the safety of SGLT2 inhibitors in older adults with multimorbidity, frailty, and polypharmacy remains unclear. Thus, future studies of SGLT2 inhibitors are needed to better evaluate their clinical effects in older adults.

Applications for Clinical Practice

This trial enrolled a dedicated patient population with CKD and demonstrated a benefit of dapagliflozin in reducing renal and cardiovascular outcomes, regardless of baseline diabetes status. These drugs (dapagliflozin as well as other SGLT2 inhibitors) will likely have a prominent role in future CKD management guidelines. Until then, several barriers remain before SGLT2 inhibitors can be widely used in clinical practice. Among these barriers are FDA approval for their use in patients with and without diabetes with an estimated GFR < 30 mL/min/1.73 m² and lowering the costs of this class of drugs.

—Rachel Litke, MD, PhD
Icahn School of Medicine at Mount Sinai
Fred Ko, MD, MS

Study Overview

Objective. To assess whether dapagliflozin added to guideline-recommended therapies is effective and safe over the long-term to reduce the rate of renal and cardiovascular events in patients across multiple chronic kidney disease (CKD) stages, with and without type 2 diabetes.

Design. The Dapagliflozin and Prevention of Adverse Outcomes in CKD (DAPA-CKD) trial (NCT03036150) was a randomized, double-blind, parallel-group, placebo-controlled, multicenter event-driven, clinical trial sponsored by Astra-Zeneca. It was conducted at 386 sites in 21 countries from February 2, 2017, to June 12, 2020. A recruitment period of 24 months and a total study duration of 45 months were initially planned. The primary efficacy analysis was based on the intention-to-treat population. This was the first randomized controlled trial designed to assess the effects of sodium-glucose co-transporter 2 (SGLT2) inhibitors on renal and cardiovascular outcomes in patients with CKD.

Setting and participants. This trial randomly assigned 4304 adult participants with CKD stages 2 to 4 (an estimated glomerular filtration rate [GFR] of 25 to 75 mL/min/1.73 m² of body-surface area) and elevated urinary albumin excretion (urinary albumin-to-creatinine ratio of 200 to 5000, measured in mg of albumin per g of creatinine) to receive dapagliflozin (10 mg once daily) or placebo. Exclusion criteria included type 1 diabetes, polycystic kidney disease, lupus nephritis, antineutrophil cytoplasmic antibody–associated vasculitis, recent immunosuppressive therapy for primary or secondary kidney disease, New York Heart Association class IV congestive heart failure, myocardial infarction, unstable angina, stroke or transient ischemic attacks, or recent coronary revascularization or valvular repair/replacement. All participants received a stable dose of renin–angiotensin system inhibitor for 4 weeks prior to screening, and the vast majority received a maximum tolerated dose at enrollment. Randomization was monitored to ensure that at least 30% of participants recruited did not have diabetes and that no more than 10% had stage 2 CKD. Participants were randomly assigned to receive dapagliflozin (n = 2152) or matching placebo (n = 2152) to ensure a 1:1 ratio of the 2 regimens. Dapagliflozin and placebo had identical appearance and administration schedules. All participants and trial personnel (except members of the independent data monitoring committee) were unaware of the trial-group assignments. After randomization, in-person study visits were conducted at 2 weeks, at 2, 4, and 8 months, and at 4-month intervals thereafter.

Main outcome measures. The primary outcome was a composite of the first occurrence of either a sustained decline in the estimated GFR of at least 50%, end-stage kidney disease, or death from renal or cardiovascular causes. Secondary outcomes, in hierarchical order, were: (1) the composite kidney outcome of a sustained decline in the estimated GFR of at least 50%, end-stage kidney disease, or death from renal causes; (2) a composite cardiovascular outcome defined as hospitalization for heart failure or death from cardiovascular causes; and (3) death from any cause. All outcomes were assessed by time-to-event analyses.

Given the extensive prior experience with dapagliflozin, only selected adverse events were recorded. These included serious adverse events, adverse events resulting in the discontinuation of dapagliflozin or placebo, and adverse events of interest to dapagliflozin (eg, volume depletion symptoms, renal events, major hypoglycemia, fractures, diabetic ketoacidosis, events leading to higher risk of lower limb amputation, and lower limb amputations).

Main results. On March 26, 2020, the independent data monitoring committee recommended stopping the trial because of clear efficacy on the basis of 408 primary outcome events. The participants were 61.8 ± 12.1 years of age, and 1425 participants (33.1%) were female. The baseline mean estimated GFR was 43.1 ± 12.4 mL/min/1.73 m², the median urinary albumin-to-creatinine ratio was 949, and 2906 participants (67.5%) had type 2 diabetes. Over a median of 2.4 years, a primary outcome event occurred in 197 participants (9.2%) in the dapagliflozin group and 312 (14.5%) in the placebo group (hazard ratio [HR], 0.61; 95% confidence interval [CI], 0.51-0.72; P < 0.001). The number of participants who needed to be treated during the trial period to prevent 1 primary outcome event was 19 (95% CI, 15-27). The beneficial effect of dapagliflozin compared with placebo was consistent across all 8 prespecified subgroups (ie, age, sex, race, geographic region, type 2 diabetes, estimated GFR, urinary albumin-to-creatinine ratio, and systolic blood pressure) for the primary outcome. The effects of dapagliflozin were similar in participants with type 2 diabetes and in those without type 2 diabetes.

The incidence of each secondary outcome was similarly lower in the dapagliflozin-treated group than in the placebo group. The HR for the composite kidney outcome of a sustained decline in the estimated GFR of at least 50%, end-stage kidney disease, or death from renal causes was 0.56 (95% CI, 0.45-0.68; P < 0.001), and the HR for the composite cardiovascular outcome of hospitalization for heart failure or death from cardiovascular causes was 0.71 (95% CI, 0.55-0.92; P = 0.009). Death occurred in 101 participants (4.7%) in the dapagliflozin group and 146 participants (6.8%) in the placebo group (HR, 0.69; 95% CI, 0.53-0.88; P = 0.004). The known safety profile of dapagliflozin was confirmed by the similar overall incidences of adverse events and serious adverse events in the dapagliflozin and placebo groups.

Conclusion. In patients with CKD, with or without type 2 diabetes, the risk of a composite of a sustained decline in the estimated GFR of at least 50%, end-stage kidney disease, or death from renal or cardiovascular causes was significantly lowered by dapagliflozin treatment.

Commentary

Although SGLT2 inhibitors were designed to reduce plasma glucose and hemoglobin A1c (HbA1c) by increasing urinary glucose excretion in a non-insulin-dependent fashion, an increasing number of clinical trials have demonstrated their possible cardiovascular and renal benefits that extend beyond glycemic control. In 2008, the US Food and Drug Administration (FDA) issued a guidance recommending the evaluation of long-term cardiovascular outcomes prior to approval and commercialization of new antidiabetic therapies to ensure minimum cardiovascular risks following the discovery of cardiovascular safety issues associated with antidiabetic compounds, including rosiglitazone, after drug approval. No one foresaw that this recommendation would lead to the discovery of new classes of antidiabetic drugs (glucagon-like peptide 1 [GLP1] and SGLT2 inhibitors) that improve cardiovascular outcomes. A series of clinical trials of SGLT2 inhibitors, including empagliflozin,¹ canagliflozin,² and dapagliflozin,³ showed a reduction in cardiovascular death and hospitalization due to heart failure among patients with type 2 diabetes. Furthermore, a meta-analysis from 2019 found that SGLT2 inhibitors reduced the risk of a composite of cardiovascular death or hospitalization for heart failure by 23% and the risk of progression of kidney failure by 45% in patients with diabetes.⁴ Thus, the strong and consistent evidence from these large and well-designed outcome trials led the American Diabetes Association in its most recent guidelines to recommend adding SGLT2 inhibitors to metformin for the treatment of patients with type 2 diabetes with or at high risk of atherosclerotic cardiovascular disease, heart failure, or CKD, regardless of baseline HbA1c levels or HbA1c target.⁵ As a result of the compelling effects of SGLT2 inhibitors on cardiovascular outcomes in diabetic patients, as well as increasing evidence that these clinical effects were independent of glycemic control, several subsequent trials were conducted to evaluate whether this new class of drugs may improve clinical outcomes in nondiabetic patients.

The Dapagliflozin and Prevention of Adverse Outcomes in Heart Failure (DAPA-HF) was the first clinical trial to investigate the effect of SGLT2 inhibitors on cardiovascular disease in nondiabetic patients. Findings from DAPA-HF showed that dapagliflozin reduced the risk of worsening heart failure or death from cardiovascular causes, independent of the presence of underlying diabetes. This initial finding resonates with a growing body of evidence^6,7 that supports the use of SGLT2 inhibitors as an adjunctive therapy for heart failure in the absence of diabetes.

The Canagliflozin and Renal Events in Diabetes with Established Nephropathy Clinical Evaluation (CREDENCE) trial showed that long-term administration of canagliflozin conferred cardiovascular, as well as renal, protection in patients with type 2 diabetes with CKD.⁸ Similar to the protective effects on heart failure, the renal benefits of SGLT2 inhibitors appeared to be independent of their blood glucose-lowering effects. Thus, these recent discoveries led to the design of the DAPA-CKD trial to further assess the long-term efficacy and safety of the SGLT2 inhibitor dapagliflozin in patients with CKD precipitated by causes other than type 2 diabetes. Although diabetes is the most common cause for CKD, it nonetheless only accounts for 40% of all CKD etiologies. To date, the only classes of medication that have been shown to slow a decline in kidney function in patients with diabetes are angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs). Given that CKD is an important contributor to illness, is associated with diminished quality of life and reduced life expectancy, and increases health care costs, the findings of the DAPA-CKD trial are particularly significant as they show a renal benefit of dapagliflozin treatment across CKD stages that is independent of underlying diabetes. Therefore, SGLT2 inhibitors may offer a new and unique treatment option for millions of patients with CKD worldwide for whom ACE inhibitors and ARBs were otherwise the only treatments to prevent kidney failure. Moreover, with a number-needed-to-treat of 19 to prevent 1 composite renal vascular event over a period of 2.4 years, dapagliflozin requires a much lower number needed to treat compared to ACE inhibitors and ARBs in similar patients.

The trial has several limitations in study design. For example, the management of diabetes and hypertension were left to the discretion of each trial site, in keeping with local clinical practice and guidelines. It is unknown whether this variability in the management of comorbidities that impact kidney function had an effect on the study’s results. In addition, the trial was stopped early as a result of recommendations from an independent committee due to the demonstrated efficacy of dapagliflozin. This may have reduced the statistical power to assess some of the secondary outcomes. Finally, the authors discussed an initial dip in the estimated GFR after initiation of dapagliflozin treatment, similar to that observed in other SGLT2 inhibitor clinical trials. However, they were unable to ascertain the reversibility of this effect after the discontinuation of dapagliflozin because assessment of GFR was not completed after trial closure. Nonetheless, the authors specified that the reversibility of this initial estimated GFR dip had been assessed and observed in other clinical trials involving dapagliflozin.

The nonglycemic benefits of SGLT2 inhibitors, including improvement in renal outcomes, have strong implications for the future management of patients with CKD. If this indication is approved by the FDA and recommended by clinical guidelines, the ease of SGLT2 inhibitor prescription (eg, minimal drug-drug interaction, no titration), treatment administration (orally once daily), and safety profile may lead to wide use of SGLT2 inhibitors by generalists, nephrologists, and endocrinologists in preserving or improving renal outcomes in patients at risk for end-stage kidney disease. Given that SGLT2 inhibitors are a new class of pharmacologic therapeutics, patient education should include a discussion of the possible side effects, such as euglycemic ketoacidosis, genital and urinary tract infection, and foot and leg amputation. Finally, as Strandberg and colleagues reported in a recent commentary,⁹ the safety of SGLT2 inhibitors in older adults with multimorbidity, frailty, and polypharmacy remains unclear. Thus, future studies of SGLT2 inhibitors are needed to better evaluate their clinical effects in older adults.

Applications for Clinical Practice

This trial enrolled a dedicated patient population with CKD and demonstrated a benefit of dapagliflozin in reducing renal and cardiovascular outcomes, regardless of baseline diabetes status. These drugs (dapagliflozin as well as other SGLT2 inhibitors) will likely have a prominent role in future CKD management guidelines. Until then, several barriers remain before SGLT2 inhibitors can be widely used in clinical practice. Among these barriers are FDA approval for their use in patients with and without diabetes with an estimated GFR < 30 mL/min/1.73 m² and lowering the costs of this class of drugs.

—Rachel Litke, MD, PhD
Icahn School of Medicine at Mount Sinai
Fred Ko, MD, MS

Study Overview

Objective. To assess whether dapagliflozin added to guideline-recommended therapies is effective and safe over the long-term to reduce the rate of renal and cardiovascular events in patients across multiple chronic kidney disease (CKD) stages, with and without type 2 diabetes.

Design. The Dapagliflozin and Prevention of Adverse Outcomes in CKD (DAPA-CKD) trial (NCT03036150) was a randomized, double-blind, parallel-group, placebo-controlled, multicenter event-driven, clinical trial sponsored by Astra-Zeneca. It was conducted at 386 sites in 21 countries from February 2, 2017, to June 12, 2020. A recruitment period of 24 months and a total study duration of 45 months were initially planned. The primary efficacy analysis was based on the intention-to-treat population. This was the first randomized controlled trial designed to assess the effects of sodium-glucose co-transporter 2 (SGLT2) inhibitors on renal and cardiovascular outcomes in patients with CKD.

Setting and participants. This trial randomly assigned 4304 adult participants with CKD stages 2 to 4 (an estimated glomerular filtration rate [GFR] of 25 to 75 mL/min/1.73 m² of body-surface area) and elevated urinary albumin excretion (urinary albumin-to-creatinine ratio of 200 to 5000, measured in mg of albumin per g of creatinine) to receive dapagliflozin (10 mg once daily) or placebo. Exclusion criteria included type 1 diabetes, polycystic kidney disease, lupus nephritis, antineutrophil cytoplasmic antibody–associated vasculitis, recent immunosuppressive therapy for primary or secondary kidney disease, New York Heart Association class IV congestive heart failure, myocardial infarction, unstable angina, stroke or transient ischemic attacks, or recent coronary revascularization or valvular repair/replacement. All participants received a stable dose of renin–angiotensin system inhibitor for 4 weeks prior to screening, and the vast majority received a maximum tolerated dose at enrollment. Randomization was monitored to ensure that at least 30% of participants recruited did not have diabetes and that no more than 10% had stage 2 CKD. Participants were randomly assigned to receive dapagliflozin (n = 2152) or matching placebo (n = 2152) to ensure a 1:1 ratio of the 2 regimens. Dapagliflozin and placebo had identical appearance and administration schedules. All participants and trial personnel (except members of the independent data monitoring committee) were unaware of the trial-group assignments. After randomization, in-person study visits were conducted at 2 weeks, at 2, 4, and 8 months, and at 4-month intervals thereafter.

Main outcome measures. The primary outcome was a composite of the first occurrence of either a sustained decline in the estimated GFR of at least 50%, end-stage kidney disease, or death from renal or cardiovascular causes. Secondary outcomes, in hierarchical order, were: (1) the composite kidney outcome of a sustained decline in the estimated GFR of at least 50%, end-stage kidney disease, or death from renal causes; (2) a composite cardiovascular outcome defined as hospitalization for heart failure or death from cardiovascular causes; and (3) death from any cause. All outcomes were assessed by time-to-event analyses.

Given the extensive prior experience with dapagliflozin, only selected adverse events were recorded. These included serious adverse events, adverse events resulting in the discontinuation of dapagliflozin or placebo, and adverse events of interest to dapagliflozin (eg, volume depletion symptoms, renal events, major hypoglycemia, fractures, diabetic ketoacidosis, events leading to higher risk of lower limb amputation, and lower limb amputations).

Main results. On March 26, 2020, the independent data monitoring committee recommended stopping the trial because of clear efficacy on the basis of 408 primary outcome events. The participants were 61.8 ± 12.1 years of age, and 1425 participants (33.1%) were female. The baseline mean estimated GFR was 43.1 ± 12.4 mL/min/1.73 m², the median urinary albumin-to-creatinine ratio was 949, and 2906 participants (67.5%) had type 2 diabetes. Over a median of 2.4 years, a primary outcome event occurred in 197 participants (9.2%) in the dapagliflozin group and 312 (14.5%) in the placebo group (hazard ratio [HR], 0.61; 95% confidence interval [CI], 0.51-0.72; P < 0.001). The number of participants who needed to be treated during the trial period to prevent 1 primary outcome event was 19 (95% CI, 15-27). The beneficial effect of dapagliflozin compared with placebo was consistent across all 8 prespecified subgroups (ie, age, sex, race, geographic region, type 2 diabetes, estimated GFR, urinary albumin-to-creatinine ratio, and systolic blood pressure) for the primary outcome. The effects of dapagliflozin were similar in participants with type 2 diabetes and in those without type 2 diabetes.

The incidence of each secondary outcome was similarly lower in the dapagliflozin-treated group than in the placebo group. The HR for the composite kidney outcome of a sustained decline in the estimated GFR of at least 50%, end-stage kidney disease, or death from renal causes was 0.56 (95% CI, 0.45-0.68; P < 0.001), and the HR for the composite cardiovascular outcome of hospitalization for heart failure or death from cardiovascular causes was 0.71 (95% CI, 0.55-0.92; P = 0.009). Death occurred in 101 participants (4.7%) in the dapagliflozin group and 146 participants (6.8%) in the placebo group (HR, 0.69; 95% CI, 0.53-0.88; P = 0.004). The known safety profile of dapagliflozin was confirmed by the similar overall incidences of adverse events and serious adverse events in the dapagliflozin and placebo groups.

Conclusion. In patients with CKD, with or without type 2 diabetes, the risk of a composite of a sustained decline in the estimated GFR of at least 50%, end-stage kidney disease, or death from renal or cardiovascular causes was significantly lowered by dapagliflozin treatment.

Commentary

Although SGLT2 inhibitors were designed to reduce plasma glucose and hemoglobin A1c (HbA1c) by increasing urinary glucose excretion in a non-insulin-dependent fashion, an increasing number of clinical trials have demonstrated their possible cardiovascular and renal benefits that extend beyond glycemic control. In 2008, the US Food and Drug Administration (FDA) issued a guidance recommending the evaluation of long-term cardiovascular outcomes prior to approval and commercialization of new antidiabetic therapies to ensure minimum cardiovascular risks following the discovery of cardiovascular safety issues associated with antidiabetic compounds, including rosiglitazone, after drug approval. No one foresaw that this recommendation would lead to the discovery of new classes of antidiabetic drugs (glucagon-like peptide 1 [GLP1] and SGLT2 inhibitors) that improve cardiovascular outcomes. A series of clinical trials of SGLT2 inhibitors, including empagliflozin,¹ canagliflozin,² and dapagliflozin,³ showed a reduction in cardiovascular death and hospitalization due to heart failure among patients with type 2 diabetes. Furthermore, a meta-analysis from 2019 found that SGLT2 inhibitors reduced the risk of a composite of cardiovascular death or hospitalization for heart failure by 23% and the risk of progression of kidney failure by 45% in patients with diabetes.⁴ Thus, the strong and consistent evidence from these large and well-designed outcome trials led the American Diabetes Association in its most recent guidelines to recommend adding SGLT2 inhibitors to metformin for the treatment of patients with type 2 diabetes with or at high risk of atherosclerotic cardiovascular disease, heart failure, or CKD, regardless of baseline HbA1c levels or HbA1c target.⁵ As a result of the compelling effects of SGLT2 inhibitors on cardiovascular outcomes in diabetic patients, as well as increasing evidence that these clinical effects were independent of glycemic control, several subsequent trials were conducted to evaluate whether this new class of drugs may improve clinical outcomes in nondiabetic patients.

The Dapagliflozin and Prevention of Adverse Outcomes in Heart Failure (DAPA-HF) was the first clinical trial to investigate the effect of SGLT2 inhibitors on cardiovascular disease in nondiabetic patients. Findings from DAPA-HF showed that dapagliflozin reduced the risk of worsening heart failure or death from cardiovascular causes, independent of the presence of underlying diabetes. This initial finding resonates with a growing body of evidence^6,7 that supports the use of SGLT2 inhibitors as an adjunctive therapy for heart failure in the absence of diabetes.

The Canagliflozin and Renal Events in Diabetes with Established Nephropathy Clinical Evaluation (CREDENCE) trial showed that long-term administration of canagliflozin conferred cardiovascular, as well as renal, protection in patients with type 2 diabetes with CKD.⁸ Similar to the protective effects on heart failure, the renal benefits of SGLT2 inhibitors appeared to be independent of their blood glucose-lowering effects. Thus, these recent discoveries led to the design of the DAPA-CKD trial to further assess the long-term efficacy and safety of the SGLT2 inhibitor dapagliflozin in patients with CKD precipitated by causes other than type 2 diabetes. Although diabetes is the most common cause for CKD, it nonetheless only accounts for 40% of all CKD etiologies. To date, the only classes of medication that have been shown to slow a decline in kidney function in patients with diabetes are angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs). Given that CKD is an important contributor to illness, is associated with diminished quality of life and reduced life expectancy, and increases health care costs, the findings of the DAPA-CKD trial are particularly significant as they show a renal benefit of dapagliflozin treatment across CKD stages that is independent of underlying diabetes. Therefore, SGLT2 inhibitors may offer a new and unique treatment option for millions of patients with CKD worldwide for whom ACE inhibitors and ARBs were otherwise the only treatments to prevent kidney failure. Moreover, with a number-needed-to-treat of 19 to prevent 1 composite renal vascular event over a period of 2.4 years, dapagliflozin requires a much lower number needed to treat compared to ACE inhibitors and ARBs in similar patients.

The trial has several limitations in study design. For example, the management of diabetes and hypertension were left to the discretion of each trial site, in keeping with local clinical practice and guidelines. It is unknown whether this variability in the management of comorbidities that impact kidney function had an effect on the study’s results. In addition, the trial was stopped early as a result of recommendations from an independent committee due to the demonstrated efficacy of dapagliflozin. This may have reduced the statistical power to assess some of the secondary outcomes. Finally, the authors discussed an initial dip in the estimated GFR after initiation of dapagliflozin treatment, similar to that observed in other SGLT2 inhibitor clinical trials. However, they were unable to ascertain the reversibility of this effect after the discontinuation of dapagliflozin because assessment of GFR was not completed after trial closure. Nonetheless, the authors specified that the reversibility of this initial estimated GFR dip had been assessed and observed in other clinical trials involving dapagliflozin.

The nonglycemic benefits of SGLT2 inhibitors, including improvement in renal outcomes, have strong implications for the future management of patients with CKD. If this indication is approved by the FDA and recommended by clinical guidelines, the ease of SGLT2 inhibitor prescription (eg, minimal drug-drug interaction, no titration), treatment administration (orally once daily), and safety profile may lead to wide use of SGLT2 inhibitors by generalists, nephrologists, and endocrinologists in preserving or improving renal outcomes in patients at risk for end-stage kidney disease. Given that SGLT2 inhibitors are a new class of pharmacologic therapeutics, patient education should include a discussion of the possible side effects, such as euglycemic ketoacidosis, genital and urinary tract infection, and foot and leg amputation. Finally, as Strandberg and colleagues reported in a recent commentary,⁹ the safety of SGLT2 inhibitors in older adults with multimorbidity, frailty, and polypharmacy remains unclear. Thus, future studies of SGLT2 inhibitors are needed to better evaluate their clinical effects in older adults.

Applications for Clinical Practice

This trial enrolled a dedicated patient population with CKD and demonstrated a benefit of dapagliflozin in reducing renal and cardiovascular outcomes, regardless of baseline diabetes status. These drugs (dapagliflozin as well as other SGLT2 inhibitors) will likely have a prominent role in future CKD management guidelines. Until then, several barriers remain before SGLT2 inhibitors can be widely used in clinical practice. Among these barriers are FDA approval for their use in patients with and without diabetes with an estimated GFR < 30 mL/min/1.73 m² and lowering the costs of this class of drugs.

—Rachel Litke, MD, PhD
Icahn School of Medicine at Mount Sinai
Fred Ko, MD, MS