Gestational diabetes is defined as glucose intolerance recognized during pregnancy. Research is necessary to achieve more accurate diagnosis, precise definition of outcome criteria and assessment of their significance, correlation of outcomes with maternal variables, and more effective therapies to control glucose levels. Until such information is available, the following guidelines are proposed. All pregnant women should be screened for glucose intolerance between the 24th and 28th weeks of pregnancy. The diagnosis should be based on O'Sullivan's oral glucose tolerance procedure. Management should include high risk pregnancy surveillance and nutritional counseling. Some centers advocate insulin administration if dietary management does not consistently maintain the fasting plasma glucose below 105 mg/dl and the 2-h postprandial glucose below 120 mg/dl. However, the point at which insulin therapy should be instituted remains to be established. All agree that close control of plasma glucose is importance in reducing fetal and perinatal morbidity and mortality.