Insulin Resistance May Impact LADA Development

Insulin resistance may play a role in the pathogenesis of latent autoimmune diabetes in adults, reported Dr. Sofia Carlsson of Karolinska Institutet, Stockholm, and the Stockholm Centre of Public Health, and colleagues.

In their population-based study, the researchers found that increased age, body mass index (BMI) of 30 kg/m2 or higher, and physical inactivity were equally significant risk factors for type 2 diabetes and for latent autoimmune diabetes in adults (LADA). “The association that we see between these factors and LADA suggests a role for insulin resistance in the development of LADA,” they wrote (Diabetologia 2007;50:55–8).

The researchers looked at incident cases of diabetes identified in two surveys conducted as part of the Nord-Trøndelag Health Study, a prospective, population-based study open to all residents, aged 20 years or older, of the Norwegian county of Nord-Trøndelag. Similar surveys were conducted from 1984 to 1986 (baseline) and from 1995 to 1997 (follow-up). The surveys included a clinical examination and questionnaires on health and lifestyle factors.

The first survey enrolled 76,885 subjects, or 90.3% of the eligible population, and the second survey enrolled 65,258 subjects, or 71.3% of the eligible population. Data were available for a cohort of 38,800 men and women who participated in both surveys and were initially free of diabetes.

Patients who reported diabetes only in the follow-up survey were given further tests. Patients underwent measurements of fasting blood glucose, fasting C-peptide, and antibodies against glutamic acid decarboxylase (GAD). Anti-GAD antibody results were expressed as an index value relative to a standard serum, with a value greater than 0.08 defined as positive.

Patients who were treated with insulin within 6 months of diagnosis and who were either anti-GAD positive or who had fasting C-peptide levels less than 150 pmol/L were classified as having type 1 diabetes. Patients who were anti-GAD positive and who had not been treated with insulin within 12 months of diagnosis were classified as having LADA. Patients who were anti-GAD negative and had not been treated with insulin within 12 months of diagnosis were classified as having type 2 diabetes.

During the 11-year period between the first and second surveys, 18 patients developed type 1 diabetes, 81 patients developed LADA, and 738 patients developed type 2 diabetes.

The risk of developing LADA or type 2 diabetes, but not type 1 diabetes, increased progressively with age. The relative risks of developing diabetes for subjects aged 60 or older, versus subjects in the 18− to 39-year age group, were 6.78 for type 2 diabetes and 5.62 for LADA. In addition, physical inactivity was associated with development of type 2 diabetes and LADA.

A BMI of 30 kg/m2 or higher was associated with significantly increased risks of LADA (relative risk 15.37) and type 2 diabetes (relative risk 15.0), but not of type 1 diabetes (relative risk 1.16). “In our population, 70% of the cases of LADA could be attributed to overweight,” wrote the authors. “If these results are confirmed in other populations, they imply that we can expect increasing rates of LADA to result from the current obesity epidemic and demographic transition.”

Insulin resistance may play a role in the pathogenesis of latent autoimmune diabetes in adults, reported Dr. Sofia Carlsson of Karolinska Institutet, Stockholm, and the Stockholm Centre of Public Health, and colleagues.

In their population-based study, the researchers found that increased age, body mass index (BMI) of 30 kg/m2 or higher, and physical inactivity were equally significant risk factors for type 2 diabetes and for latent autoimmune diabetes in adults (LADA). “The association that we see between these factors and LADA suggests a role for insulin resistance in the development of LADA,” they wrote (Diabetologia 2007;50:55–8).

The researchers looked at incident cases of diabetes identified in two surveys conducted as part of the Nord-Trøndelag Health Study, a prospective, population-based study open to all residents, aged 20 years or older, of the Norwegian county of Nord-Trøndelag. Similar surveys were conducted from 1984 to 1986 (baseline) and from 1995 to 1997 (follow-up). The surveys included a clinical examination and questionnaires on health and lifestyle factors.

The first survey enrolled 76,885 subjects, or 90.3% of the eligible population, and the second survey enrolled 65,258 subjects, or 71.3% of the eligible population. Data were available for a cohort of 38,800 men and women who participated in both surveys and were initially free of diabetes.

Patients who reported diabetes only in the follow-up survey were given further tests. Patients underwent measurements of fasting blood glucose, fasting C-peptide, and antibodies against glutamic acid decarboxylase (GAD). Anti-GAD antibody results were expressed as an index value relative to a standard serum, with a value greater than 0.08 defined as positive.

Patients who were treated with insulin within 6 months of diagnosis and who were either anti-GAD positive or who had fasting C-peptide levels less than 150 pmol/L were classified as having type 1 diabetes. Patients who were anti-GAD positive and who had not been treated with insulin within 12 months of diagnosis were classified as having LADA. Patients who were anti-GAD negative and had not been treated with insulin within 12 months of diagnosis were classified as having type 2 diabetes.

During the 11-year period between the first and second surveys, 18 patients developed type 1 diabetes, 81 patients developed LADA, and 738 patients developed type 2 diabetes.

The risk of developing LADA or type 2 diabetes, but not type 1 diabetes, increased progressively with age. The relative risks of developing diabetes for subjects aged 60 or older, versus subjects in the 18− to 39-year age group, were 6.78 for type 2 diabetes and 5.62 for LADA. In addition, physical inactivity was associated with development of type 2 diabetes and LADA.

A BMI of 30 kg/m2 or higher was associated with significantly increased risks of LADA (relative risk 15.37) and type 2 diabetes (relative risk 15.0), but not of type 1 diabetes (relative risk 1.16). “In our population, 70% of the cases of LADA could be attributed to overweight,” wrote the authors. “If these results are confirmed in other populations, they imply that we can expect increasing rates of LADA to result from the current obesity epidemic and demographic transition.”

Insulin resistance may play a role in the pathogenesis of latent autoimmune diabetes in adults, reported Dr. Sofia Carlsson of Karolinska Institutet, Stockholm, and the Stockholm Centre of Public Health, and colleagues.

In their population-based study, the researchers found that increased age, body mass index (BMI) of 30 kg/m2 or higher, and physical inactivity were equally significant risk factors for type 2 diabetes and for latent autoimmune diabetes in adults (LADA). “The association that we see between these factors and LADA suggests a role for insulin resistance in the development of LADA,” they wrote (Diabetologia 2007;50:55–8).

The researchers looked at incident cases of diabetes identified in two surveys conducted as part of the Nord-Trøndelag Health Study, a prospective, population-based study open to all residents, aged 20 years or older, of the Norwegian county of Nord-Trøndelag. Similar surveys were conducted from 1984 to 1986 (baseline) and from 1995 to 1997 (follow-up). The surveys included a clinical examination and questionnaires on health and lifestyle factors.

The first survey enrolled 76,885 subjects, or 90.3% of the eligible population, and the second survey enrolled 65,258 subjects, or 71.3% of the eligible population. Data were available for a cohort of 38,800 men and women who participated in both surveys and were initially free of diabetes.

Patients who reported diabetes only in the follow-up survey were given further tests. Patients underwent measurements of fasting blood glucose, fasting C-peptide, and antibodies against glutamic acid decarboxylase (GAD). Anti-GAD antibody results were expressed as an index value relative to a standard serum, with a value greater than 0.08 defined as positive.

Patients who were treated with insulin within 6 months of diagnosis and who were either anti-GAD positive or who had fasting C-peptide levels less than 150 pmol/L were classified as having type 1 diabetes. Patients who were anti-GAD positive and who had not been treated with insulin within 12 months of diagnosis were classified as having LADA. Patients who were anti-GAD negative and had not been treated with insulin within 12 months of diagnosis were classified as having type 2 diabetes.

During the 11-year period between the first and second surveys, 18 patients developed type 1 diabetes, 81 patients developed LADA, and 738 patients developed type 2 diabetes.

The risk of developing LADA or type 2 diabetes, but not type 1 diabetes, increased progressively with age. The relative risks of developing diabetes for subjects aged 60 or older, versus subjects in the 18− to 39-year age group, were 6.78 for type 2 diabetes and 5.62 for LADA. In addition, physical inactivity was associated with development of type 2 diabetes and LADA.

A BMI of 30 kg/m2 or higher was associated with significantly increased risks of LADA (relative risk 15.37) and type 2 diabetes (relative risk 15.0), but not of type 1 diabetes (relative risk 1.16). “In our population, 70% of the cases of LADA could be attributed to overweight,” wrote the authors. “If these results are confirmed in other populations, they imply that we can expect increasing rates of LADA to result from the current obesity epidemic and demographic transition.”