Gestational Diabetes Mellitus and the Risks of Overall and Type-Specific Cardiovascular Diseases: A Population- and Sibling-Matched Cohort Study.

OBJECTIVE To evaluate associations between gestational diabetes mellitus (GDM) and various incident cardiovascular disease (CVD) end points, considering the effects of the mediating role of type 2 diabetes and shared environmental/familial factors. RESEARCH DESIGN AND METHODS This population-based cohort study included 10,02,486 parous women in Denmark during 1978–2016. We used Cox regression to 1) examine the associations of GDM with overall and type-specific CVDs using full-cohort and sibling-matched analysis, 2) quantify the impact of type 2 diabetes after GDM using mediation analysis, and 3) assess whether these associations were modified by prepregnancy obesity or maternal history of CVD. RESULTS Women with a history of GDM had a 40% increased overall CVD risk (hazard ratio [HR] 1.40, 95% CI 1.35–1.45). Sibling-matched analyses yielded similar results (HR, 1.44; 95% CI 1.28–1.62). The proportion of association between GDM and overall CVD explained by subsequent type 2 diabetes was 23.3% (15.4–32.8%). We observed increased risks of specific CVDs, including 65% increased stroke risk and more than twofold risks for myocardial infarction, heart failure, and peripheral artery disease. The elevated overall risks were more pronounced among women with GDM and prepregnancy obesity or maternal history of CVD. CONCLUSIONS A history of GDM was associated with increased risks of overall and specific CVDs. Increased risks were partly explained by subsequent type 2 diabetes, and the need to identify other pathways remains important. Continuous monitoring of women with a history of GDM, especially those with prepregnancy obesity or maternal history of CVD, may provide better opportunities to reduce their cardiovascular risk.