Our objective was to retrospectively evaluate glycemic excursion and insulin dosage in the perioperative period in children and adolescents with type I diabetes mellitus receiving prolonged intravenous insulin infusion for 2-3 days compared to conventional subcutaneous insulin treatment. A retrospective review of surgical admissions at the Children's Hospital of Los Angeles in patients with type I diabetes mellitus was conducted for the 3-year period from July 1989 to June 1992, to evaluate two treatment protocols used during that period. For the nine admissions in group 1, patients received 0.06-0.1 units regular insulin/kg/h beginning 2 h prior to surgery and lasting for 2-3 days postoperatively; while, for the ten admissions in group 2 subjects were given subcutaneous regular and intermediate-acting insulin as 2-4 injections daily, with the regular insulin dose prior to surgery decreased to 66-75% of usual. Blood glucose levels were determined at the bedside at hourly intervals and insulin dose adjustment done with the aim of achieving blood glucose levels between 5.5 and 8.3 mmol/L (100-150 mg/dL). The mean bedside blood glucose levels for group 2 were significantly higher 1 h prior to surgery and during the intraoperative period (p < 0.05). In the postoperative period, group 2 blood glucose levels were significantly higher at multiple times for up to 3 days with multiple levels greater than 11.1 mmol/L (200 mg/dL), which was not seen in group 1. The mean insulin dosage (units/kg) prior to admission was not different for the two groups. On the day of surgery and during postoperative days 1 and 2, patients in group 1 received a greater insulin dosage than group 2 subjects (p < 0.025). In group 1, insulin dosage was increased 23% and 15% over baseline for postoperative days 1 and 2, respectively, then, by day 3, was decreased back toward the baseline. In group 2 subjects, a 13.8% increase occurred on the day of surgery due to extra insulin given immediately following the procedures, followed by a 5.4, 44.2, and 66.6% increase over baseline for postoperative days 1 through 3, respectively. In conclusion, meticulous glycemic control was readily achieved in the perioperative period with a constant intravenous insulin infusion for up to 3 days in children and adolescents with type I diabetes. To achieve glycemic control, insulin dosage needs to be increased on the day of surgery and for approximately 2 postoperative days.