Abstract The proposed risks from abnormal glucose tolerance in pregnancy are continuous. Gestational diabetes is thus an arbitrary condition. The risks to the fetus are largely determined by fetal size, and those of the mother by the severity of glucose intolerance. Screening policies vary throughout the world, and all have deficiencies. Policies should be determined locally, as population and organizational issues will influence efficacy. Clinicians need to agree diagnostic criteria as minor alterations in these can alter the disease incidence. There is no universal agreement on diagnostic testing. There is no conclusive evidence from randomized trials that therapy alters pregnancy outcome in gestational diabetes. Therapy targeted at those fetuses shown to have evidence of hyperinsulinism may be the best way forward. Follow-up of women with early diagnosis, or who have required insulin during pregnancy is vital to allow prevention strategies against type 2 diabetes.