During a 5 1/2-year period we have seen 171 pregnant women with established insulin-independent diabetes. Eleven of them booked late and received virtually no treatment. The remaining 160 patients were managed primarily by regulating diet; when this failed metformin or glibenclamide therapy was instituted. Insulin was used when diet and oral drugs failed. Diabetic control was considered adequate if fasting blood glucose levels remained below 5,5 mmol/l and post-prandial levels were below 6,7 mmol/l. Twenty-five per cent of patients were well controlled on diet only during the duration of their pregnancies, with 1 perinatal death. Glibenclamide and metformin appear to be safe drugs during pregnancy when properly used. The overall perinatal mortality rate was 78/1 000; 42/1 000 since January 1978, as compared with 364/1 000 in the 'untreated' group. Only 18 babies were large (> 4 000 g), respiratory distress rarely occurred and hyaline membrane disease was virtually absent. Hypoglycaemia of the neonate was seldom a problem, but was most frequently related to the use of glibenclamide. Neonatal hypoglycaemia may be abolished if patients receiving tablets or insulin are given continuous, intravenous low-dose insulin 24 hours before planned delivery. The prevalence of major abnormalities was as least double that among infants of non-diabetic mothers.