This document discusses gestational diabetes mellitus (GDM), including its definition, types, risk factors, screening recommendations, and pathophysiology. GDM is a type of diabetes that develops during pregnancy and usually resolves after giving birth. However, women with GDM and their babies are at higher risk for developing type 2 diabetes later in life. The document recommends screening all pregnant women for GDM between 24-28 weeks of gestation using a 75g oral glucose tolerance test. A diagnosis of GDM is made if one plasma glucose value meets or exceeds the threshold.