24-Hour Blood Glucose Profiles in Insulin-Dependent Diabetics Treated with Intravenous Insulin Infusion Systems: A Comparison between Closed- and Open-Loop Systems

. The aim of this study was to compare the 24-hour blood glucose profiles of insulin-dependent diabetics during treatment with preprogramed insulin delivery systems with those of patients on treatment with the artificial beta cell (Biostator®). Mean blood glucose (MGB) was 4.4±0.5 mmol/l for 15 controls, 5.8 ± 1.0 for 53 patients on open-loop and 6.0 ± 0.6 for 20 patients on closed-loop treatment. MBG was significantly higher in diabetics than in non-diabetics, but the difference between the two diabetic populations was not significant. Mean amplitude of blood glucose excursion was 1.8 ± 0.6, 4.3 ± 1.3 and 3.5 ± 0.8 mmol/l respectively, the difference between the diabetic groups being significant. No hypoglycemia was seen in patients during closed-loop treatment, whereas this was the case in 10 of 53 patients on treatment with open-loop systems. Physical exercise resulted in small but normal decreases in blood glucose without hypoglycemia. Plasma insulin was within the normal range during both regimes. It is concluded that blood glucose control during treatment with closed-loop system is superior to that during treatment with open-loop systems. However, under standard conditions i.v. insulin infusion with preprogramed pump devices resulted in blood glucose fluctuations comparable with those during Biostator® treatment.