Role of Type 2 Diabetes in Determining Retinal, Renal, and Cardiovascular Outcomes in Women With Previous Gestational Diabetes Mellitus

OBJECTIVE Women who have gestational diabetes mellitus (GDM) have elevated lifetime risks for the development of type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD), compared with their peers. However, it is not known whether their risk of CVD is dependent upon the development of T2DM. Thus, we sought to evaluate the role of T2DM in determining vascular outcomes in women with previous GDM. RESEARCH DESIGN AND METHODS All women in Ontario, Canada, with a live-birth pregnancy between April 1994 and March 2014 (n = 1,515,079) were stratified into the following four groups: women with GDM in whom T2DM subsequently developed (n = 15,585, median age 32 years); those with GDM in whom T2DM did not develop (n = 41,299; median age 32 years); women who did not have GDM but in whom T2DM developed (n = 49,397; median age 31 years); and those with neither GDM nor T2DM (n = 1,408,798; median age 30 years). Women were followed over a median time of 10.0 years for the development of microvascular and macrovascular outcomes. RESULTS Among women who had GDM, only those in whom T2DM developed had an increased risk of vitrectomy/photocoagulation (hazard ratio [HR] 4.49, 95% CI 3.90-5.17), renal dialysis (HR 7.52, 5.24-10.81), and hospitalization for foot infection (HR 4.32, 3.42-5.46) (all P < 0.0001). However, for macrovascular outcomes, both women with GDM in whom T2DM developed and those in whom T2DM did not develop had increased risks of CVD (HR 2.82; 2.41-3.30; P < 0.0001; and HR 1.30; 1.07-1.59; P = 0.008, respectively) and coronary artery disease (HR 3.54; 2.96-4.23; P < 0.0001; and HR 1.41; 1.11-1.80; P = 0.005, respectively), although absolute event rates were very low. CONCLUSIONS Women with GDM have an elevated risk of cardiovascular outcomes, even in the absence of T2DM. In contrast, microvascular risk emerges only in those in whom T2DM develops.