The purpose of this study was to determine the subcutaneous insulin requirements for rapid, effective regulation of blood glucose in patients with poorly controlled type II diabetes mellitus by using an intravenous insulin infusion protocol. The insulin infusion achieved a mean (+/-SD) overnight blood glucose concentration of 101 +/- 15 mg/dL and 24-hour glucose concentration of 118 +/- 18 mg/dL. The intravenous insulin requirement of 81 +/- 32 U/day correlated well (P<0.001) with the subsequent subcutaneous insulin requirement of 84 +/- 43 U/day necessary to maintain preprandial glucose values of 112 +/- 15 mg/dL. Insulin requirements ranged from 0.2 to 2.0 U/kg per day (95% confidence interval, 0.4 to 1.6). Weaker correlations were noted between total insulin requirements and weight (r = 0.60) or body mass index (r = 0.57); no correlations were observed with age, duration of diabetes, or antecedent glycemic control as reflected by glycosylated hemoglobin values. These findings may be useful for initiating insulin treatment on an ambulatory basis.