Insulin Production Rate in Normal Man as an Estimate for Calibration of Continuous Intravenous Insulin Infusion in Insulin-dependent Diabetic Patients

Abstract

This study examines the feasibility of deriving the 24-h insulin requirement of insulin-dependent diabetic patients who were devoid of any endogenous insulin release (IDD) from the insulin-production rate (IPR) of healthy man (basal, 17 mU/min; stimulated 1.35 U/12.5 g glucose). To this end, continuous intravenous insulin infusion (CIVII) was initiated at a precalculated rate of 41.2 ± 4.6 (SD) U/24 h in IDD (N = 12). Blood glucose profiles were compared with those obtained during intermittent subcutaneous (s.c.) insulin therapy (IIT) and those of healthy controls (N = 7). Regular insulin (Hoechst CS) was infused with an adapted Mill Hill Infuser at a basal infusion rate of 1.6 U/h (6:00 a.m. to 8:00 p.m.), and of 0.8 U/h from 8:00 p.m. to 6:00 a.m. Preprandial insulin (3.2–6.4 U) was added for breakfast, lunch, and dinner. Daily individual food intake totaled 7688 ± 784 kJ (1836 ± 187 kcal)/24 h including 184 ± 37 g of glucose. Proper control of blood glucose (BG) (mean BG 105 ± 10 mg/dl; mean amplitude of glycemic excursions 54 ± 18 mg/dl; and 1 h postprandial BG levels not exceeding 160 mg/dl) and of plasma concentrations of β-hydroxybutyrate and lactate was maintained by 41.4 ± 4.4 U insulin/24 h. Although BG values only approximated the upper normal range as seen in healthy controls, they were well within the range reported by others during CIVII. Therefore, we conclude that in adult IDD completely devoid of endogenous insulin (1) the IPR of normal man can be used during CIVII as an estimate for the patient's minimal insulin requirement per 24 h, and (2) this approach allows for a blood glucose profile close to the upper range of a normal control group. Thus, deriving a patient's daily insulin dose from the insulin production rate of healthy man may add an additional experimental protocol which aids in making general calculations of a necessary insulin dose instead of using trial and error or a closed-loop insulin infusion system.