Gestational Diabetes Carries CVD Risk Years Later

Richard Mark Kirkner

February 01, 2021

Erica P. Gunderson, PhD

Women who've had gestational diabetes are 40% more likely to develop coronary artery calcification later in life than those who have never had it, and attaining normal glycemic levels doesn't diminish their midlife risk for atherosclerotic cardiovascular disease.

"The new finding from this study is that women with gestational diabetes had twice the risk of coronary artery calcium, compared to women who never had gestational diabetes, even though both groups attained normal blood sugar levels many years after pregnancy," lead author Erica P. Gunderson, PhD, MS, MPH, said in an interview about a community-based prospective cohort study of young adults followed for up to 25 years, which was published in Circulation (2021 Feb 1. doi: 10.1161/CIRCULATIONAHA.120.047320).

Previous studies have reported a higher risk of heart disease in women who had gestational diabetes (GD) and later developed type 2 diabetes, but they didn't elucidate whether that risk carried over in GD patients whose glycemic levels were normal after pregnancy. In 2018, the American College of Cardiology/American Heart Association Cholesterol Clinical Practice Guidelines specified that a history of GD increases women's risk for coronary artery calcification (CAC).

This study analyzed data of 1,133 women ages 18-30 enrolled in the Coronary Artery Risk Development in Young Adults (CARDIA) study who had no diabetes in the baseline years of 1985-1986 and had given birth at least once in the ensuing 25 years. They had glucose tolerance testing at baseline and up to five times through the study period, along with evaluation for GD status and coronary artery calcification CAC measurements at least once at years 15, 20 and 25 (2001-2011).

CARDIA enrolled 5,155 young Black and White men and women ages 18-30 from four distinct geographic areas: Birmingham, Ala.; Chicago; Minneapolis; and Oakland, Calif. About 52% of the study population was Black.

Of the women who'd given birth, 139 (12%) had GD. Their average age at follow-up was 47.6 years, and 25% of the GD patients (34) had CAC, compared with 15% (149/994) in the non-GD group.

Gunderson noted that the same relative risk for CAC applied to women who had GD and went on to develop prediabetes or were diagnosed with type 2 diabetes during follow-up.

Risks Persist Even in Normoglycemia

In the GD group, the adjusted hazard ratio for having CAC with normoglycemia was 2.3 (95% confidence interval, 1.34-4.09). The researchers also calculated HRs for prediabetes and incident diabetes: 1.5 (95% CI, 1.06-2.24) in no-GD and 2.1 (95% CI, 1.09-4.17) for GD for prediabetes; and 2.2 (95% CI, 1.3-3.62) and 2.02 (95% CI, 0.98-4.19), respectively, for incident diabetes (P = .003).

"This means the risk of heart disease may be increased substantially in women with a history of gestational diabetes and may not diminish even if their blood-sugar levels remain normal for years later," said Gunderson, an epidemiologist and senior research scientist at the Kaiser Permanente Northern California Division of Research in Oakland.

"The clinical implications of our findings are that women with previous GD may benefit from enhanced traditional CVD [cardiovascular disease] risk factor testing – i.e., for hypertension, dyslipidemia, and hyperinsulinemia," Gunderson said. "Our findings also suggest that it could be beneficial to incorporate history of GD into risk calculators to improve CVD risk stratification and prevention."

Strong Findings Argue for More Frequent CVD Screening

These study results may be the strongest data to date on the long-term effects of GD, said Prakash Deedwania, MD, professor of cardiology at the University of California, San Francisco. "It's the strongest in the sense in that it's sponsored, involved four different communities in different parts of the United States, enrolled individuals when they were young and followed them, and saw very few patients drop out for such a long-term study." The study reported follow-up data on 72% of patients at 25 years, a rate Deedwania noted was "excellent."

"Patients who have had GD should be screened aggressively – for not only diabetes, but other cardiovascular risk factors – early on to minimize the subsequent risk of cardiovascular disease is a very important point of this study," he added. In the absence of a clinical guideline, Deedwania suggested women with GD might have screening for CV risk factors every 5-7 years depending on their risk profile, but emphasized that parameter isn't settled.

Future research should focus on the link between GD and CVD risk, Gunderson said. "Research is needed to better characterize the severity of GD in relation to CVD outcomes, and to identify critical pregnancy-related periods to modify cardiometabolic risk." The latter would include life-course studies across the full pregnancy continuum from preconception to lactation. "Interventions for primary prevention of CVD and the importance of modifiable lifestyle behaviors with the highest relevance to reduce both diabetes and CVD risks during the first year postpartum merit increased research investigation," she added.

Future studies might also explore the role of inflammation in the GD-CVD relationship, Deedwania said. "My hypothesis is, and it's purely a hypothesis, that perhaps the presence of coronary artery calcification scores score in these individuals who were described as having normal glucose but who could be at risk could very well be related to the beginning of inflammation."

Gunderson and Deedwania have no financial relationships to disclose. The study was funded by the National Institute of Diabetes and Digestive and Kidney Diseases and the National Heart, Lung, and Blood Institute.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.

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