Predictors of Abnormal Glucose Tolerance in the Early Postpartum Period in Patients with Gestational Diabetes

This study was designed to investigate the clinical predictors of abnormal glucose tolerance 5-7 weeks after delivery. Subjects were 155 women diagnosed with gestational diabetes mellitus (GDM) between October 2005 and September 2013 whose pregnancy and delivery were managed at our center. Subjects were divided into a normal glucose tolerance group (NGT; n = 113), or abnormal glucose tolerance group (AGT; n = 42) with borderline or overt diabetes mellitus, based on 75-g oral glucose tolerance test (75 gOGTT) results 5-7 weeks after delivery. We extracted profiles by which abnormal glucose tolerance levels 5-7 weeks after delivery were predicted using a classification and regression tree (CART) from parameters measured at the time of GDM diagnosis. Logistic regression analysis was used to determine prediction accuracy. Subjects with fasting plasma glucose (FPG) ≥92 mg/dL and immuno-reactive insulin level <100 μU/mL 60 min after load (IRI60min) at time of diagnosis showed a significantly higher risk of developing abnormal glucose tolerance 5-7 weeks after delivery than subjects with FPG <92 mg/dL (p < 0.0001). Subjects with FPG ≥92 mg/dL and IRI60min ≥ 100 μU/mL had the same risk as those with FPG of <92 mg/dL. Patients with gestational diabetes who met the criteria specified above at diagnosis were at a higher risk of developing diabetes mellitus in the future. By explaining this issue to patients, we expect to improve the rate of postpartum follow-up. This should facilitate early detection of diabetes, and help prevent associated complications.