Greater T2D Risk Seen in Women with Gestational Diabetes

Long-term cardiovascular health may be compromised for mothers with gestational diabetes mellitus (GDM), a new study reported.

A retrospective cohort study found women with gestational diabetes mellitus (GDM) were nearly 22 times more likely to develop type 2 diabetes, in an adjusted model (adjusted incidence rate ratio 21.96, 95% CI 18.31-26.34, P<0.001), according to Barbara Daly, PhD, RN, of the University of Auckland in New Zealand, and colleagues.

The risks for hypertension and ischemic heart disease were also significantly increased among women who previously experienced GDM (aIRR 1.85, 95% CI 1.59-2.16, P<0.001; aIRR 2.78, 1.37-5.66, P=0.005, respectively), they reported in PLOS Medicine.

However, during the 25-year study period, there was no increased risk seen for cerebrovascular disease, which included stroke and transient ischemic attack, among women with GDM (aIRR 0.95, 95% CI 0.51-1.77, P=0.87).

Drawing upon the Health Improvement Network database in the U.K., the analysis included 9,118 women with a history of GDM, who were then matched with 37,281 pregnant controls. Women with GDM were more likely to be non-white, and were overweight or obese at baseline.

Among women who developed ischemic heart disease during follow-up, only around 36% also developed type 2 diabetes. The authors pointed out this suggested “that the risk of cardiovascular disease is not always mediated through type 2 diabetes.”

In an ethnic subgroup analysis, white, South Asian, and Afro-Caribbean women with GDM were all more likely to develop type 2 diabetes post-partum:

• White: IRR 35.2 (95% CI 20.0-58.5)
• South Asian: IRR 22.15 (95% CI 6.42-76.4)
• Afro-Caribbean: IRR 15.40 (95% CI 6.54-36.25)

“The current National Institute for Health and Care Excellence (NICE) guidelines recommend screening for type 2 diabetes (between 6 and 13 weeks postpartum and an annual glycated hemoglobin test) and lifestyle changes (weight control, diet, and exercise) for women diagnosed with GDM,” the authors highlighted.

However, only 58% of women with GDM in the analysis reported having a glycemic measurement in the first year post-partum, according to medical records. This eventually decreased to only 40% and 24% of such women undergoing a glycemic measurement in years 2 and 3 after delivery.

The authors also added, “there is no recommendation to screen, identify, and actively manage cardiovascular risk factors (including hypertension, dyslipidemia, and smoking) in women diagnosed with GDM in the postpartum period in the current 2015 NICE guidelines.”

“Guideline recommendations for screening and management of hypertension, lipids, and smoking cessation are lacking and need to be reviewed,” they suggested.

While around 80% of women with GDM reported a blood pressure measurement in the first year after delivery, only half of those women had a measurement in years 2 and 3 post-partum. During the first 3 years after delivery, only around 28% and 23% of women with GDM had serum cholesterol or triglycerides measured, respectively.

 Although the authors stated their findings were congruent with prior observational analyses, they noted their effects estimates were higher for type 2 diabetes and ischemic heart disease compared with prior studies, as well as lower effect estimates for hypertension.

“The findings report on a large population and identify an at-risk group of relatively young women ideally suited for targeting of risk factor management to improve long-term metabolic and cardiovascular outcomes,” they wrote, adding that “targeting these high-risk women may also provide better value for money for prevention programs, as they are already known to general practice.”

“While the value of preventing cardiovascular outcomes requires further studies, there is some evidence that targeting this subgroup of women may yield benefits in reducing conversion to type 2 diabetes,” the authors stated.