Purpose: A postpartum oral glucose tolerance test (OGTT) is recommended in all women with recent gestational diabetes (GDM), but is performed in only 50% of the women. Our purpose was to determine maternal and neonatal risk factors associated with persisting diabetes early postpartum in women with recent GDM. Study design: 1654 women with diagnosis of GDM in the recent pregnancy underwent a 75 g 2 hr OGTT 4-16 weeks postpartum interpreted by NDDG criteria. Maternal demographic and glycemic parameters (DM screening, fasting and post-challenge glucose and the area under the curve [AUC] of the diagnostic OGTT, highest fasting), and neonatal outcome parameters (birth weight, body mass index, major malformations, still-birth) were tested by univariate and multivariate logistic regression for their predictive risk of a diabetic postpartum OGTT. For continuous variables the relative risk for DM was additionally compared between the highest and lowest quartile of the cohort. Results: Postpartum diabetes was diagnosed in 218 (13.2%), impaired glucose tolerance in 199 (12.0%) women. Several maternal demographic and all glycemic parameters were associated with the risk of postpartum diabetes. Out of the fetal parameters only major malformations (n = 40) were predictive (OR 2.6; Cl 1.2-5.2, p=0,009). A diabetic postpartum OGTT was found in 27% of the women who gave birth to a newborn with malformations. The fasting glucose, the AUC of the OGTT, the 50 mg diabetes screening (GCT), the history of GDM and the gestational age at diagnosis were the independent predictors in the multivariate analysis. The fasting glucose and the AUC were the best predictors (p = 0,0001). The fasting glucose was divided into quartiles. Within the 3 rd quartile (> 108 mg/dl) the OR was 3.7 (Cl 1.4-11.8), and within the 4th quartile (> 122 mg/dl) the OR was 6.8 (Cl 2.1-22.2) compared to glucose values within the lowest quartile. Diagnosis of GDM > 26 weeks of gestation (3 rd quartile) reduced the risk by half (OR 0.5, Cl 0.3-0.9) compared with diagnosis < 17 weeks. Conclusion: A postpartum OGTT should be performed in all women after pregnancies with GDM. There is an increased risk for a persisting postpartum diabetes with prenatal fasting glucose values above 108 mg/dl, diagnosis of GDM before 26 weeks of gesta-tion, history of GDM and birth of a child with major malformations.