Predictors of postpartum glucose intolerance in women with gestational diabetes mellitus: a prospective cohort study in Ethiopia based on the updated diagnostic criteria

OBJECTIVES: To identify the incidence of postpartum glucose intolerance and develop a prediction model based on antenatal characteristics to predict postpartum glucose intolerance. DESIGN: Prospective cohort study. SETTING: Gondar town public health facilities in Northwest Ethiopia. PARTICIPANTS: Women who had gestational diabetes mellitus were advised to undergo postpartum oral glucose tolerance test at 6–12 weeks of delivery. MAIN OUTCOME: Postpartum glucose intolerance. DATA ANALYSIS: Predictors of postpartum glucose intolerance were identified using multivariable logistic regression analysis. The discriminative power of the predictor variables for postpartum glucose intolerance and the model accuracy were computed by area under the receiver operating characteristic curve and estimated by area under the curve (AUC) with 95% CI. RESULTS: A total of 112 (85.5%) women with gestational diabetes mellitus returned and completed the postpartum oral glucose tolerance test. The incidence of postpartum glucose intolerance was 21.4% (95% CI14.3 to 28.4), inclusive of 18.7% pre-diabetes and 2.7% diabetes. Multivariable logistic regression analysis revealed that advanced maternal age, high fasting plasma glucose level at diagnosis, overweight and/or obesity, and antenatal depression were predictors of postpartum glucose intolerance. The AUC of the final reduced model to predict postpartum glucose intolerance was 0.884 (95% CI 0.822 to 0.937). Fasting plasma glucose at diagnosis of gestational diabetes mellitus (AUC=0.736, 95% CI0.616 to 0.845) and overweight and/or obesity (AUC=0.718, 95% CI 0.614 to 0.814) were better predictors of postpartum glucose intolerance. Moreover, the AUC for the combined predictors of fasting plasma glucose at diagnosis and mid-upper arm circumference was 0.822 (95% CI 0.722 to 0.907), which was the best predictor. CONCLUSIONS: The incidence of postpartum glucose intolerance was high among women with gestational diabetes mellitus. Antenatal predictors modestly predicted postpartum glucose intolerance. The findings suggest ongoing glucose screening is indicated for all women with gestational diabetes mellitus.