Fasting and 2-hour plasma glucose, and HbA1c in pregnancy and the postpartum risk of diabetes among Chinese women with gestational diabetes

•We assessed postpartum diabetes risk among women with prior gestational diabetes mellitus (GDM).•2 h glucose and HbA1c were positive predictors for postpartum diabetes.•2 h glucose and HbA1c predict diabetes risk, independent of fasting glucose.

AimsVery few studies have assessed the association of fasting and 2 h glucose, and HbA1c during pregnancy with postpartum diabetes risk among women with prior gestational diabetes mellitus (GDM). We assessed the association of fasting glucose, 2 h glucose and HbA1c at 26-30 gestational weeks with postpartum diabetes risk among women with prior GDM.MethodsA cohort study in 1263 GDM women at 1-5 years after delivery was performed. Cox proportional hazards regression models were used to evaluate the association of fasting and 2 h plasma glucose, and HbA1c at 26-30 gestational weeks with the risk of diabetes at postpartum.ResultsThe multivariable-adjusted (age, pre-pregnancy body mass index, weight gain during pregnancy, current body mass index, family history of diabetes, marital status, education, family income, smoking status, passive smoking, leisure-time physical activity, alcohol drinking, and intake of energy, saturated fat, and dietary fiber) hazard ratios of postpartum diabetes were 1.61 (95% confidence interval [CI]: 1.36-1.91) for each 1 mmol/l increase in fasting glucose during pregnancy, 1.63 (95% CI: 1.45-1.84) for each 1 mmol/l increase in 2 h glucose during pregnancy, 2.11 (95% CI: 1.50-2.97) for each 1 unit (%) increase in HbA1c during pregnancy. When fasting glucose, 2 h glucose and HbA1c during pregnancy were entered multivariable-adjusted model simultaneously, 2 h glucose and HbA1c but not fasting glucose remained to be significant and positive predictors for postpartum diabetes.ConclusionsFor women with prior GDM, 2 h plasma glucose and HbA1c during pregnancy are independent predictors of postpartum diabetes, but fasting plasma glucose during pregnancy is not.