Healthy Diet After Gestational Diabetes Cuts Hypertension Risk

Marlene Busko

April 27, 2016

ROCKVILLE, MD — In a large study of women who had gestational diabetes, those who had the healthiest diets were about 20% to 30% less likely to develop hypertension than those who had the worst diets, after adjustment for multiple variables[1].

These findings are from an 18.5-year follow-up of women in the Nurses' Health Study 2 who had gestational diabetes. The researchers looked at the women's likelihood of incident hypertension based on their adherence to three healthy eating patterns—the Alternative Healthy Eating Index-2010, the Mediterranean diet, and the Dietary Approaches to Stop Hypertension (DASH).

The study, by Dr Shanshan Li (National Institute of Child Health and Human Development [NICHD]/National Institutes of Health [NIH], Rockville, MD) and colleagues, was published April 18, 2016 in Hypertension.

Although it is well-known that gestational diabetes increases the risk of developing type 2 diabetes, the researchers had also previously shown that gestational diabetes confers a 26% increased risk of future hypertension[2]. The new study showed that a healthy diet might mitigate this risk.

"We cannot tell which of the three diets is better than the other," senior author Dr Cuilin Zhang (NICHD/NIH) told heartwire from Medscape. However, all three diets, which "are high in fruits, vegetables, fish, and whole grains and lower in salt, red meat, and processed meats," have been shown to have cardiovascular benefits, she noted.

"If a woman is diagnosed as having gestational diabetes during pregnancy, her physician may want to tell her that she is at a high risk of developing type 2 diabetes, cardiovascular diseases, and/or risk factors later in her life," and thus she should keep physically active, follow a healthy eating pattern, watch her weight, and have regular physical exams—at least an annual check of blood glucose and blood pressure, Zhang advised.

Gestational Diabetes, Three Diets, and New Hypertension

The researchers conducted a prospective cohort study of data from 1989 to 2011 from 3818 women in the Nurses' Health Study 2 who had a history of gestational diabetes but no initial hypertension.

The women, who were 24 to 44 at baseline, reported lifestyle information and medical history (including incident hypertension) every 2 years in self-administered questionnaires. They also filled in a food frequency questionnaire every 4 years, which the researchers used to calculate an adherence score for three dietary patterns.

Risk of Hypertension, Most vs Least Adherent to a Healthy Dieta

Diet RR (95% CI)b P
Alternative Healthy Eating Index 0.76 (0.61–0.94) 0.03
DASH 0.72 (0.58–0.90) 0.01
Mediterranean 0.70 (0.56–0.88) 0.002
a. Where most adherent to a healthy diet is the top quartile and least adherent is lowest quartile, in cohort of women with gestational diabetes
b. Relative risk adjusted for age, parity, age at first birth, race/ethnicity, family history of diabetes, contraceptive use, menopausal status, cigarette smoking, alcohol intake, total energy intake, physical activity, birth weight, hypertensive disorder of pregnancy, family history of hypertension, aspirin use, use of anti-inflammatory medication, body-mass index (BMI) at age 18, and updated BMI

Compared with other women, those with gestational diabetes were more likely to have a sedentary lifestyle, be obese, and develop diabetes, the researchers note. An increase in BMI explained about 20% to 30% of the increased risk of hypertension seen with a poor diet.

In this high-risk population, the magnitude of blood-pressure benefits with these three healthy diets was similar to that observed in the general population, Li and colleagues report.

The DASH diet has consistently been shown to lower risk of hypertension and is recommended to prevent and treat high blood pressure, the researchers note, but all three diets have similar components and have similar beneficial effects.

"The high fiber content from whole grains and legumes, a characteristic from the three dietary patterns, could reduce glucose absorption, improve insulin sensitivity, improve endothelial function, and have anti-inflammatory and antioxidant effects," they suggest.

"Fruits and vegetables contain high potassium and vitamin K, ascorbic acid, and antioxidants, which could reduce vascular oxidative stress, endothelial impairment, atrial stiffness, and blood pressure," they add

Thus, "findings from the present study indicate that women with a history of [gestational diabetes] may benefit from adhering to a healthy dietary pattern characterized by rich intake in fruits and vegetables, whole grains" that is "low in red and processed meats and low in refined grain," Li and colleagues summarize.

This was a group of highly educated, mainly white women, so future studies are needed in other groups, the researchers urge, especially since previous research suggests that Hispanic and African American women have a higher risk of hypertension than white women.

The authors have no relevant financial relationships.

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