One hundred and forty-eight patients with well controlled insulin dependent diabetes that were allowed to labour spontaneously from 1981 to 1994 were reviewed. There were 2 perinatal deaths, giving a perinatal mortality rate of 13.5/1000. One hundred and twenty-four patients (84 per cent) had a normal vaginal delivery, 13 (9 per cent) forceps delivery and 11 (7 per cent) caesarean section. Twenty-one infants (14 per cent) required admission to a Special Care Baby Unit. One third of infants weighed 4 Kg or more, however there was only 1 case of shoulder dystocia. We compared these results with those of the general hospital population of 1987. The 2 main differences are; 1) the Caesarean section rate in labour was higher for this diabetic group than for the general hospital population, 7 per cent versus 3.4 per cent, 2) the birth weight was heavier, 33 per cent of infants of the diabetic group weighed 4 Kg or more versus 18 per cent of the general hospital population. The other parameters were comparable. We conclude that conservative management of pregnancy in well controlled diabetic women is advantageous, resulting in a high vaginal delivery rate without an increase in shoulder dystocia, and a low perinatal morbidity and mortality rate.