The purpose of this study was to test the hypothesis that the incidence of shoulder dystocia could be reduced in insulin-requiring diabetic women by elective induction of labor at 38 to 39 weeks of gestation. A prospective study protocol in which labor was induced at 38 to 39 weeks of gestation in insulin-requiring diabetic women was executed between January 1, 1990, and July 31, 1994 (n = 96). The outcome was compared to the results of a previous protocol (years 1983 to 1989) in which the pregnancies were allowed to progress to spontaneous labor, unless fetal health became compromised (n = 164). The incidence of shoulder dystocia in patients in whom labor was electively induced at 38 to 39 weeks of gestation was 1.4% as compared to 10.2% in patients who delivered beyond 40 weeks' gestation (p < 0.05). No increase in cesarean section rate was demonstrated. We conclude that elective induction of labor is suggested for insulin-requiring diabetic women in order to reduce the incidence of shoulder dystocia.