Objective — Women who develop gestational diabetes mellitus (GDM) have an elevated lifetime risk of cardiovascular disease, which has been attributed to an adverse cardiovascular risk factor profile that is apparent even within the first year postpartum. Given its presence in the early postpartum, we hypothesized that this adverse cardiovascular risk factor profile may develop over time in the years before pregnancy.
Research Design and Methods — With population-based administrative databases, we identified all nulliparous women in Ontario, Canada, who had singleton pregnancies between January 2011 and December 2016 and two or more measurements of the following analytes between 2007 and the start of pregnancy: A1C, fasting glucose, random glucose, lipids, and transaminases. This population consisted of 8,047 women who developed GDM and 93,114 women who did not.
Results — The two most recent pregravid tests were performed at a median of 0.61 years and 1.86 years before pregnancy, respectively. Women who went on to develop GDM had higher pregravid A1C, fasting glucose, random glucose, LDL cholesterol, triglycerides, and ALT and lower HDL-cholesterol than their peers (all P < 0.0001). Notably, in the years before pregnancy, women who went on to develop GDM had higher annual increases than their peers in A1C (1.9-fold higher) (difference 0.0089%/year [95% CI 0.0043–0.0135]) and random glucose (4.3-fold), greater annual decrease in HDL cholesterol (5.5-fold), and lesser annual decline in LDL cholesterol (0.4-fold) (all P ≤ 0.0002). During this time, fasting glucose and triglycerides increased in women who developed GDM but decreased in their peers (both P < 0.0001).
Conclusions — The adverse cardiovascular risk factor profile of women with GDM evolves over time in the years before pregnancy.