In Denmark, gestational diabetes mellitus (GDM) develops in about 2% of all pregnant women. The discussion of GDM is complicated by lack of consensus regarding screening methods, diagnosis and treatment. Observational studies indicate that untreated GDM is associated with an increased risk of maternal and perinatal morbidity, and that the offspring of GDM mothers tend to be at increased risk of developing diabetes and adiposity as a result of an abnormal intrauterine environment. Several follow-up studies have shown that women with previous GDM run a considerable risk of developing diabetes (especially type 2 diabetes) later in life. Intervention strategies for this high risk group are suggested.