Recent studies show that higher blood glucose values after a 75 g oral glucose tolerance test in pregnancy are associated with higher rates of perinatal and maternal complications. Treatment of gestational diabetes mellitus (hyperglycaemia in pregnancy) reduces the risk of complications. Gestational diabetes mellitus is an asymptomatic condition. Screening is the only strategy for diagnosing this disorder of pregnancy in time, in order to provide treatment. Until recently, there was no uniformity concerning diagnostic strategy and treatment of gestational diabetes mellitus in the Netherlands, possibly due to lack of evidence on the risk of complications and the effectiveness of treatment. Results of several recent studies show that early detection and treatment of gestational diabetes mellitus are effective. By means of a more active screening and treatment policy it should be possible to reduce the perinatal and maternal complications as a result of gestational diabetes mellitus.