Improved perinatal outcome is associated with the prevention of hyperglycemia during pregnancy in diabetic women. To determine whether the method of insulin administration influences the degree of diabetic control obtained, we randomized 22 pregnant diabetic women to intensive conventional insulin therapy (N = 11) and insulin pump therapy (N = 11). Frequent outpatient visits; home glucose monitoring, at least six times daily; and frequent telephone contact were offered to all subjects. Patients were hospitalized in the inpatient clinical research center each trimester for a 24-hour metabolic profile. There were no differences between the two treatment groups with respect to outpatient mean glucose levels, symptomatic hypoglycemia, or glycosylated hemoglobin levels, or with respect to inpatient mean glucose level, glycemic excursions, chemical hypoglycemia, or hyperglycemia. Excellent metabolic control was achieved with both treatment methods.