Association between Gestational Diabetes and Cardiovascular Disease within 24 Months Postpartum

Background Cardiovascular disease is the leading cause of death among women in the United States. It is well established that gestational diabetes mellitus (GDM) is associated with an overall lifetime increased risk of cardiometabolic disease, even among those without intercurrent type 2 diabetes. However, the association between GDM and short-term risk of cardiovascular disease (CVD) is unclear. Establishing short-term risks of CVD for patients with GDM has significant potential to inform early screening and targeted intervention strategies to reduce premature cardiovascular morbidity among women. Objective We aimed to estimate the risk of cardiovascular disease diagnoses in the first 24 months postpartum among patients with GDM compared with patients without GDM. Study Design Our longitudinal population-based study included pregnant individuals with deliveries during 2007-2019 in the Maine Health Data Organization's All Payer Claims Data. We excluded records with gestational age <20 weeks and deliveries with non-Maine residence, multifetal gestation, those without insurance in the month of delivery or the 3 months before pregnancy, those with implausible time to next pregnancy (<60 days), pre-gestational diabetes mellitus, and any pre-pregnancy diagnosis of the cardiovascular conditions being examined postpartum. GDM and CVD (heart failure, ischemic heart disease, arrhythmia/cardiac arrest, cardiomyopathy, cerebrovascular disease/stroke, and new chronic hypertension) were identified by ICD 9/10 diagnosis codes. Cox proportional hazards models were used to estimate hazard ratios (HR), adjusting for potential confounding factors. We assessed whether the association between GDM and chronic hypertension was mediated by intercurrent diabetes mellitus. Results Of the 84,746 pregnancies examined, the cumulative risk of CVD within 24 months postpartum for those with GDM vs. without GDM was 0.13% vs. 0.20% for heart failure, 0.16% vs. 0.14% for ischemic heart disease, 0.60% vs. 0.44% for cerebrovascular disease/stroke, 0.22% vs. 0.16% for arrhythmia/cardiac arrest, 0.20% vs. 0.20% for cardiomyopathy, and 4.19% vs. 1.83% for new chronic hypertension. After adjusting for potential confounders, those with GDM have an increased risk of new chronic hypertension (adjusted hazard ratio (aHR) 1.56 (95% CI 1.32-1.86)) within the first 24 months postpartum as compared to those without GDM. There was no association between GDM and ischemic heart disease (aHR 0.75 (95% CI 0.34-1.65)), cerebrovascular disease/stroke (aHR 1.13 (95% CI 0.78-1.66)), arrhythmia/cardiac arrest (aHR 1.16 (95% CI 0.59-2.29)), or cardiomyopathy (aHR 0.75 (95% CI 0.40-1.41)) within the first 24 months postpartum. Those with GDM appeared to have a decreased risk of heart failure within 24 months postpartum, aHR 0.45 (95% CI (0.21-0.98)). Our mediation analyses estimated that 28% of the effect of GDM on new chronic hypertension was mediated through intercurrent diabetes mellitus. Conclusion Patients with GDM have a significantly increased risk of new chronic hypertension as early as 24 months postpartum. The majority of this effect was not due to the development of diabetes mellitus. Our findings suggest that all women with GDM need careful monitoring and screening for new chronic hypertension in the first 2 years postpartum.