The National Diabetes Education Program joins the American College of Obstetricians and Gynecologists (the College) to promote opportunities for obstetrician–gynecologists (ob-gyns) and other primary care providers to better meet the long-term health needs of women with prior gestational diabetes mellitus (GDM) and their children. Up to one third of GDM women may have diabetes or prediabetes postpartum, yet only about half of these women are tested postpartum, and about a quarter are tested 6–12 weeks postpartum. Women with GDM face a lifelong increased risk for subsequent diabetes, primarily type 2 diabetes mellitus. Timely testing for prediabetes may provide an opportunity for ob-gyns to prevent or delay the onset of type 2 diabetes mellitus through diet, physical activity, weight management, and pharmacologic intervention. The College and the American Diabetes Association recommend testing women with a history of GDM at 6–12 weeks postpartum. If the postpartum test is normal, retest every 3 years and at the first prenatal visit in a subsequent pregnancy. If prediabetes is diagnosed, test annually. Because children of GDM pregnancies face an increased risk for obesity and type 2 diabetes mellitus, families need support to develop healthy eating and physical activity behaviors. Current criteria indicate that GDM occurs in 2% to 10% of all pregnancies. If new GDM diagnostic criteria are used, the frequency of GDM may increase to about 18% of pregnancies annually. The projected increase in the number of women with GDM and the potential subsequent associated risks underscore the need for proactive long-term primary care treatment of the mother and her children.