Gestational diabetes mellitus (GDM) is the most common metabolic disturbance during pregnancy. The prevalence is rising and correlates with the increase in maternal obesity over recent decades. The etiology of GDM is complex, with genetic and environmental factors implicated in mechanistic and epidemiological studies. GDM begets important short- and long-term health risks for the mother, developing fetus, and offspring. This includes the high likelihood of subsequent maternal type 2 diabetes (T2DM), and possible adverse cardiometabolic phenotypes in the offspring. The most clinically and cost-effective methods of screening for GDM remain uncertain. Whilst treatments with lifestyle and pharmacological interventions have demonstrated short-term benefits, the long-term impact for the offspring of intrauterine exposure to antidiabetic medication remains unclear.