Aims: Very 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. Methods: A 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. Results: The 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. Conclusions: For 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.
