Gestational diabetes mellitus (GDM) is one of the most common complications of pregnancy. It is defined as diabetes that is first recognized during pregnancy. The diagnosis of GDM is important because it impacts maternal health care during and after pregnancy. The American Diabetes Association, American Congress of Obstetrics and Gynecology, the World Health Organization, and the National Diabetes Data Group all have recommendations for screening; however, there is no consensus. The Hyperglycemia and Adverse Pregnancy Outcome Research Cooperative Study Group published their findings that show hyperglycemia has a significant effect on pregnancy outcome. In addition, recent studies showed that treatment of mild hyperglycemia may affect adverse outcomes. However, at this time no new guidelines for screening and diagnosis of gestational diabetes have been published. This article summarizes the current state of screening for gestational diabetes.