Gestational Diabetes History and Glucose Tolerance After Pregnancy Associated With Coronary Artery Calcium in Women During Midlife

Background: Gestational diabetes (GD) leads to earlier onset and heightened risk of type 2 diabetes, a strong risk factor for cardiovascular disease (CVD). However, it is unclear whether attaining normoglycemia can ameliorate the excess CVD risk associated with GD history. This study sought to evaluate GD history and glucose tolerance after pregnancy associated with coronary artery calcification (CAC) in women, a manifestation of atherosclerotic CVD and a predictor of CVD clinical events. Methods: Data were obtained from the CARDIA study (Coronary Artery Risk Development in Young Adults), a US multicenter, community-based prospective cohort of young Black (50%) and White adults aged 18 to 30 years at baseline (1985–1986). The sample included 1133 women without diabetes at baseline, who had ≥1 singleton births (n=2066) during follow-up, glucose tolerance testing at baseline and up to 5 times during 25 years (1986–2011), GD status, and CAC measurements obtained from 1 or more follow up examinations at years 15, 20, and 25 (2001–2011). CAC was measured by noncontrast cardiac computed tomography; dichotomized as Any CAC (score>0) or No CAC (score=0). Complementary log-log models for interval-censored data estimated adjusted hazard ratios of CAC and 95% confidence intervals for GD history and subsequent glucose tolerance groups (normoglycemia, prediabetes, or incident diabetes) on average 14.7 years after the last birth adjusted for prepregnancy and follow-up covariates. Results: Of 1133 women, 139 (12.3%) reported GD and were 47.6 years of age (4.8 SD) at follow-up. CAC was present in 25% (34/139) of women with GD and 15% (149/994) of women with no GD. In comparison with no GD/normoglycemia, adjusted hazard ratios (95% CIs) were 1.54 (1.06–2.24) for no GD/prediabetes and 2.17 (1.30–3.62) for no GD/incident diabetes, and 2.34 (1.34–4.09), 2.13 (1.09–4.17), and 2.02 (0.98–4.19) for GD/normoglycemia, GD/prediabetes, and GD/incident diabetes, respectively (overall P =0.003). Conclusions: Women without previous GD showed a graded increase in the risk of CAC associated with worsening glucose tolerance. Women with a history of GD had a 2-fold higher risk of CAC across all subsequent levels of glucose tolerance. Midlife atherosclerotic CVD risk among women with previous GD is not diminished by attaining normoglycemia.