Gestational diabetes is defined as a disturbed carbohydrate metabolism present during pregnancy but reverting to normal after delivery. It constitutes a current social problem since it may occur in 2 -3% of pregnancies and the incidence may be much greater in selected populations (Freinkel & Josimovich 1980). The known impact of this condition on perinatal mortality, foetal macrosomia and neonatal hypoglycaemia have dictated the need for an increased awareness, improved identification and special therapeutic management. Since the best therapeutic management of women with gestational diabetes,has not yet been established, we decided to investigate the following groups of pregnant women on the basis of upper normal limits of fasting blood sugar (FBS) 105 mg% (Metzger et al. 1981). Therefore the aim of the present study was to evaluate the effect and the value of insulin administration, once or twice daily, in patients with gestational diabetes. Subjects and MethodsA total of 103 pregnant women participated in the present study. In all women the diagnosis of gestational diabetes was made between the 24th and 32nd week of pregnancy, using the criteria of O'Sullivan & Mahan (1964). In ad¬ dition we attempted to graduate the severity of the disorder on the basis of the upper normal values for fasting plasma glucose. More speci¬ fically we investigated 35 women, with GD and FBS<105 mg% who were treated only by Diet (Group A), 21 women, with GD and FBS>105 mg% treated only by Diet (Group B) and 47 women, with GD and FBS>105 mg%, treated