Women with a history of gestational diabetes mellitus (GDM) have a high risk of progression to type 2 diabetes mellitus (T2DM). Risk factors are similar for GDM and T2DM and include, among others, obesity, family history, and ethnic background. GDM is also associated with the metabolic syndrome. Women with impaired glucose tolerance or "prediabetes" postpartum have the highest risk of progression. In women with impaired glucose tolerance, lifestyle modification or pharmacologic therapy may prevent or delay the onset of T2DM.