Unlike minor operations, major surgeries require strict glycemic control using intravenous insulin infusion in patients with diabetes. The postoperative transition to subcutaneous insulin, if needed, can begin several hours before discontinuing intravenous insulin, by reinitiation of basal insulin re-initiation. Basal-bolus insulin regimens are safer and more effective in hospitalized patients than supplemental-scale regular insulin. (J Korean Diabetes 2011;12:150-153)