Abstract. Even minor abnormalities of maternal carbohydrate metabolism may influence foetal development. This study aimed at examining the relations between impaired glucose tolerance and blood glucose behavior under a standardized diet in late pregnancy and at looking for the obstetrical and neonatal outcome after normalization of blood glucose profiles in gestational diabetics. The study included 97 women in the second half of pregnancy. Severely abnormal blood glucose profiles were observed in most patients with impaired glucose tolerance who had a fasting capillary blood glucose concentration above 4.7 mmol/l. Normalization could usually only be achieved by combining a strict dietary regimen with insulin treatment. The obstetrical and neonatal outcome in the group of patients treated with diet plus insulin was similar to that in the group of patients treated with diet alone.