Gestational diabetes mellitus-part 1: screening and diagnosis

Gestational diabetes mellitus (GDM) is a glucose tolerance disorder and one of the most common pregnancy complications. GDM shows no symptoms. In the time window of 24 + 0-27 + 6 weeks of pregnancy, the women first receive a screening test with 50 g glucose. If the screening is positive, an oral glucose tolerance test (oGTT) follows with 75 g or 100 g glucose over 2 or 3 h. The diagnostic threshold for GDM diagnosis is not handled uniformly internationally. While the International Association of the Diabetes and Pregnancy Study Groups (IADPSG) criteria with pretest are recommended in Germany, the Carpenter-Coustan criteria are commonly used in North America. Current findings show that a one-step approach compared to the two-step approach increases the GDM incidence and the rate of insulin therapies without improving clinically relevant endpoints. Screening before 24 weeks does not bring any advantages either. The most important differential diagnosis is the monogenic GCK-MODY (GCK: glucokinase, MODY: maturity-onset diabetes of the young).