Increased risk for microvascular complications among women with gestational diabetes in the third trimester

•Women with gestational diabetes had an increased risk of microalbuminuria (odds ratio 2.4, 95% confidence interval 1.1 to 5.2, p = 0.006).•Diastolic blood pressure and A1c were independently associated with microalbuminuria.•Retinopathy did not differ between women with and without gestational diabetes.•The assumption that microvascular complications occur only years after the onset of overt hyperglycemia may be flawed. The risk of microvascular disease has been thought to commence with the onset of overt diabetes. Women with gestational diabetes have only had a short-term exposure to frank hyperglycemia, but, due to underlying β-cell dysfunction, they may also have had long-term exposure to mild degrees of hyperglycemia. The aim of the study was to determine whether women with gestational diabetes are at increased risk for microalbuminuria and retinopathy compared to women with normal glucose tolerance in pregnancy. We recruited women aged ≥ 25 years with singleton pregnancies at 32 to 40 weeks’ gestational age, with and without gestational diabetes. Women with hypertension, preeclampsia, or pre-gestational diabetes were excluded. Of 372 women included in the study, 195 had gestational diabetes. The prevalence of microalbuminuria was 15% among those with gestational diabetes versus 6% in those with normal glucose tolerance (adjusted odds ratio 2.4, 95% confidence interval 1.1 to 5.2, p = 0.006). Diastolic blood pressure and HbA1c were associated with microalbuminuria. The prevalence of retinopathy did not differ between groups (10% versus 11%). Women with gestational diabetes have an increased risk of microalbuminuria in the third trimester, despite having been exposed to only a brief period of overt hyperglycemia.