OBJECTIVE: To compare diabetic and nondiabetic pregnant women near term regarding the accuracy of predicted birth weight by the gestation-adjusted projection method using ultrasonographic measurements. METHODS: Patients with singleton pregnancies who had diabetes and who underwent sonograms between 34.0 weeks and 36.9 weeks formed the study group. The control group was comprised of nondiabetic women who had sonograms in the same gestational age range. The absolute birth weight errors and absolute percent errors in the study group and the controls were compared with t tests. RESULTS: A total of 133 diabetic women and 1690 controls were included in the study. The mean (± standard deviation) absolute error of the predicted birth weight was 265 ± 210 g in the diabetic women and 261 ± 204 g in the control group (P = .87). The mean (± standard deviation) absolute percent error was 7.4% ± 6.3% for diabetic women compared with 8.3% ± 6.6% for the controls (P = .14). CONCLUSION: Prediction of birth weight using the gestation-adjusted projection method is as accurate in diabetic women as in controls.