Screening and diagnosis of GDM. There is a lack of uniform strategies for screening and diagnosing GDM globally (Table 1). The first diagnostic criteria for gestational diabetes were provided by O´Sullivan and Mahan in the 1960’s based on a 3-hour 100 g OGTT.26 These criteria have been derived to identify women at high risk of developing diabetes after pregnancy. Many medical organizations around the world followed the original work of O’Sullivan and Mahan,26 and modified by either Carpenter and Coustan,27 or the National Diabetes Data Group (NDDG),1 although frequently selecting different thresholds for GDM diagnosis.