Gestational Diabetes Flags Elevated Risk for Hypertension

Major Finding: Women who had gestational diabetes were 41% more likely to develop hypertension during a 14-year follow-up, compared with those who had not had the condition.

Data Source: A nested prospective cohort study of 26,384 women initially aged 25-44 years who had at least one singleton pregnancy.

Disclosures: Ms. Tobias reported that she had no relevant conflicts of interest.

SEATTLE — Women who have had gestational diabetes may be at elevated risk for hypertension even after established risk factors are taken into account, a nested cohort study indicates.

Using data from the Nurses' Health Study II, researchers followed more than 26,000 women from an index pregnancy for up to 14 years. Those with gestational diabetes during that pregnancy were 41% more likely to develop hypertension even after adjustment for potential confounders such as body mass index, diet, and family history of hypertension.

“These women may represent a target group for intervention to prevent or delay the onset of hypertension, which is a public health concern in the United States,” lead investigator Deirdre K. Tobias concluded.

“The mechanism by which gestational diabetes mellitus could lead to an increased risk of hypertension and other metabolic complications is not yet established,” said Ms. Tobias, who is a doctoral student at the Harvard School of Public Health, Boston.

One possibility is that these conditions have shared risk factors, she noted. Another is that gestational diabetes itself increases the risk of hypertension, for example, by causing vascular damage that manifests later in time.

The Nurses' Health Study II is a prospective cohort study of women aged 25-44 years at baseline that began in 1989.

Extensive questionnaires completed at baseline and biennially include questions about physician-diagnosed gestational diabetes and hypertension.

Ms. Tobias and her colleagues included in their sample the 26,384 women who reported having at least one singleton pregnancy between 1991 (the first year in which dietary data were collected) and 2005, did not have type 2 diabetes or hypertension, had not experienced gestational diabetes in a previous pregnancy, and had not had previous cardiovascular disease.

Study results showed that 6% of the women had gestational diabetes during their index pregnancy. Women with and without gestational diabetes had a mean age of 32 years at baseline, and 7% in each group were current smokers.

However, those with gestational diabetes had a higher body mass index (25 vs. 23 kg/m

Overall, 9% of the women developed hypertension during follow-up, and the cumulative incidence was higher among those who had had gestational diabetes.

After adjustment for potential confounders, women who experienced gestational diabetes still had a 41% higher risk of developing hypertension.

Moreover, compared with women who experienced neither gestational diabetes nor type 2 diabetes, those who experienced both had a near tripling of the risk of developing hypertension.

“It is possible that there was residual or unmeasured confounding,” acknowledged Ms. Tobias. “For example, in our cohort, we were unable to capture pregnancy-related characteristics, such as weight gain or severity of gestational diabetes.”

The generalizability of the findings may be limited, given the women's higher age at baseline and the fact that most were white, she noted.

Major Finding: Women who had gestational diabetes were 41% more likely to develop hypertension during a 14-year follow-up, compared with those who had not had the condition.

Data Source: A nested prospective cohort study of 26,384 women initially aged 25-44 years who had at least one singleton pregnancy.

Disclosures: Ms. Tobias reported that she had no relevant conflicts of interest.

SEATTLE — Women who have had gestational diabetes may be at elevated risk for hypertension even after established risk factors are taken into account, a nested cohort study indicates.

Using data from the Nurses' Health Study II, researchers followed more than 26,000 women from an index pregnancy for up to 14 years. Those with gestational diabetes during that pregnancy were 41% more likely to develop hypertension even after adjustment for potential confounders such as body mass index, diet, and family history of hypertension.

“These women may represent a target group for intervention to prevent or delay the onset of hypertension, which is a public health concern in the United States,” lead investigator Deirdre K. Tobias concluded.

“The mechanism by which gestational diabetes mellitus could lead to an increased risk of hypertension and other metabolic complications is not yet established,” said Ms. Tobias, who is a doctoral student at the Harvard School of Public Health, Boston.

One possibility is that these conditions have shared risk factors, she noted. Another is that gestational diabetes itself increases the risk of hypertension, for example, by causing vascular damage that manifests later in time.

The Nurses' Health Study II is a prospective cohort study of women aged 25-44 years at baseline that began in 1989.

Extensive questionnaires completed at baseline and biennially include questions about physician-diagnosed gestational diabetes and hypertension.

Ms. Tobias and her colleagues included in their sample the 26,384 women who reported having at least one singleton pregnancy between 1991 (the first year in which dietary data were collected) and 2005, did not have type 2 diabetes or hypertension, had not experienced gestational diabetes in a previous pregnancy, and had not had previous cardiovascular disease.

Study results showed that 6% of the women had gestational diabetes during their index pregnancy. Women with and without gestational diabetes had a mean age of 32 years at baseline, and 7% in each group were current smokers.

However, those with gestational diabetes had a higher body mass index (25 vs. 23 kg/m

Overall, 9% of the women developed hypertension during follow-up, and the cumulative incidence was higher among those who had had gestational diabetes.

After adjustment for potential confounders, women who experienced gestational diabetes still had a 41% higher risk of developing hypertension.

Moreover, compared with women who experienced neither gestational diabetes nor type 2 diabetes, those who experienced both had a near tripling of the risk of developing hypertension.

“It is possible that there was residual or unmeasured confounding,” acknowledged Ms. Tobias. “For example, in our cohort, we were unable to capture pregnancy-related characteristics, such as weight gain or severity of gestational diabetes.”

The generalizability of the findings may be limited, given the women's higher age at baseline and the fact that most were white, she noted.

Major Finding: Women who had gestational diabetes were 41% more likely to develop hypertension during a 14-year follow-up, compared with those who had not had the condition.

Data Source: A nested prospective cohort study of 26,384 women initially aged 25-44 years who had at least one singleton pregnancy.

Disclosures: Ms. Tobias reported that she had no relevant conflicts of interest.

SEATTLE — Women who have had gestational diabetes may be at elevated risk for hypertension even after established risk factors are taken into account, a nested cohort study indicates.

Using data from the Nurses' Health Study II, researchers followed more than 26,000 women from an index pregnancy for up to 14 years. Those with gestational diabetes during that pregnancy were 41% more likely to develop hypertension even after adjustment for potential confounders such as body mass index, diet, and family history of hypertension.

“These women may represent a target group for intervention to prevent or delay the onset of hypertension, which is a public health concern in the United States,” lead investigator Deirdre K. Tobias concluded.

“The mechanism by which gestational diabetes mellitus could lead to an increased risk of hypertension and other metabolic complications is not yet established,” said Ms. Tobias, who is a doctoral student at the Harvard School of Public Health, Boston.

One possibility is that these conditions have shared risk factors, she noted. Another is that gestational diabetes itself increases the risk of hypertension, for example, by causing vascular damage that manifests later in time.

The Nurses' Health Study II is a prospective cohort study of women aged 25-44 years at baseline that began in 1989.

Extensive questionnaires completed at baseline and biennially include questions about physician-diagnosed gestational diabetes and hypertension.

Ms. Tobias and her colleagues included in their sample the 26,384 women who reported having at least one singleton pregnancy between 1991 (the first year in which dietary data were collected) and 2005, did not have type 2 diabetes or hypertension, had not experienced gestational diabetes in a previous pregnancy, and had not had previous cardiovascular disease.

Study results showed that 6% of the women had gestational diabetes during their index pregnancy. Women with and without gestational diabetes had a mean age of 32 years at baseline, and 7% in each group were current smokers.

However, those with gestational diabetes had a higher body mass index (25 vs. 23 kg/m

Overall, 9% of the women developed hypertension during follow-up, and the cumulative incidence was higher among those who had had gestational diabetes.

After adjustment for potential confounders, women who experienced gestational diabetes still had a 41% higher risk of developing hypertension.

Moreover, compared with women who experienced neither gestational diabetes nor type 2 diabetes, those who experienced both had a near tripling of the risk of developing hypertension.

“It is possible that there was residual or unmeasured confounding,” acknowledged Ms. Tobias. “For example, in our cohort, we were unable to capture pregnancy-related characteristics, such as weight gain or severity of gestational diabetes.”

The generalizability of the findings may be limited, given the women's higher age at baseline and the fact that most were white, she noted.