Background and aims: Incidences of T1DM and T2DM as well as gestational diabetes mellitus (GDM) are increasing worldwide. Given that women with previous GDM have increased risk of developing diabetes in the future compared with those normoglycaemic during pregnancy, however their participation in the postpartum screening is low the aims of our study were (1) to ascertain a frequency of early (up to 12 months post-delivery) postpartum conversion of GDM into permanent diabetes (DM) or impaired glucose tolerance (IGT), (2) to test whether the degree of glucose intolerance diagnosed by standard criteria at the time of GDM diagnosis correlates with the degree of early postpartum glucose (in)tolerance and (3) to find eventual significant predictive factors for early postpartum conversion of GDM to DM/IGT from glycemic indices routinely measured in the mid-trimester of gravidity. Materials and methods: We carried out a retrospective epidemiological analysis of electronic health records data of an ethnically homogenous, central European population cohort of women with GDM diagnosis followed in a single medical centre (Diabetes centrum of the University Hospital Brno) during the period 2005 – 2011 that underwent repeated oGTT up to 1 year after the index delivery (n=1090 for the purpose of incidence analysis). A subgroup of 305 GDM subjects with compete anthropometric, clinical and biochemical data that underwent both mid-trimester and postpartum 3-point oGTT test in the central laboratory of the University Hospital Brno was chosen for more detail analysis of risks and predictive factors. Results: Any DM/IGF was detected in a total of 11.7% subjects, of those 4.1% had DM (2.8% T2DM and 1.3% T1DM). Glycaemia in all three time-points of mid-trimester oGTT, area under the curve (AUCoGTT) and mid-trimester HbA1c were significantly associated with the postpartum disorder (P under 0.05, Mann-Whitney). A highly statistically significant trend was identified in the number of above threshold values during mid-trimester oGTT and the postpartum DM/IGF conversion (P<1x10-12): 8% of patients with one oGTT value above cut-off, 25% with two and 65% with all three were diagnosed with DM/IGT 1year postpartum. Uni- and multivariate regression models were used to identify the best predictive parameters (FPG and AUCoGTT) for the construction of ROC. Conclusion: Parameters of glucose metabolism measured between 24-28th week of pregnancy exhibit – apart from diagnostic value for GDM diagnosis – significant predictive potential for early reoccurrence or postpartum persistence of glucose intolerance. Considering generally low-compliance of GDM women in postpartum screening, risk-based stratification of GDM population could improve efficiency of the screening for diabetes after delivery. Acknowledgement: Supported by grants NT/11405 from The Ministry of Health of Czech Republic and MUNI/A/0839/2011