Converting Continuous Insulin Infusion to Subcutaneous Insulin Glargine After Cardiac Surgery Using Percentage-Based Versus Weight-Based Dosing: A Pilot Trial

BACKGROUND: Most studies report using percentage of total daily insulin (TDI) for converting therapy from continuous insulin infusion to subcutaneous insulin in cardiac surgery patients. Few studies have evaluated the efficacy of using body weight to calculate the basal insulin dose. OBJECTIVE: To compare the efficacy and safety of dosing insulin glargine by weight versus percentage of TDI in cardiac surgery patients transitioning from continuous insulin infusion to subcutaneous insulin. METHODS: We conducted a prospective, randomized, open-label, pilot study. Study patients who had a preoperative weight less than 100 kg and were receiving at least 6 hours of a continuous insulin infusion were randomized to receive either 50% of their TDI requirement or 0.5 units/kg of glargine as a one-time dose 2 hours before stopping the continuous insulin infusion. All patients were administered subcutaneous corrective insulin. Blood glucose monitoring occurred before each meal, at bedtime, and with morning laboratory tests for 24 hours after administration of the glargine dose. RESULTS: A total of 200 blood glucose measurements were performed in each group. The percentage of blood glucose measurements in target range (80-140 mg/dL) was similar between the weight-based group and the percentage-based group (66% vs 64%, p = 0.75). Median blood glucose after transition was 120 mg/dL (interquartile range [IQR] 99-147) in the weight-based group compared to 127 mg/dL (IQR 107-149; p = 0.03) in the percentage-based group. The median glargine dose was higher in the weight-based group (41 units; IQR 36-44) than in the weight-based group (24 units; IQR 14-30, p < 0.001). The rate of hypoglycemia (blood glucose < 60 mg/dL) was 2.5% in each group. CONCLUSIONS: In this small cohort, dosing insulin glargine by weight proved to be safe, but larger scale studies are needed before adopting weight-based dosing in this patient population.