A greater proportion of women of reproductive age are now overweight or obese. Gestational diabetes mellitus and maternal obesity are associated with long-term adverse consequences in the offspring and subsequent generations, and are important drivers of the escalating global burden of diabetes and cardiovascular disease. We review the evidence linking gestational diabetes mellitus and maternal obesity with a greater risk of metabolic compromise in the offspring. We use an evolutionary perspective to elucidate the origins of gestational diabetes. Focusing efforts on maternal health is an important approach to combating the growing burden of diabetes and other noncommunicable diseases.