Feasibility of Automating Insulin Delivery for the Treatment of Type 1 Diabetes

TLDR

An automated closed‑loop insulin delivery system using subcutaneous glucose sensing and insulin delivery, evaluated over ~30 h in 10 type 1 diabetes subjects, employed a β‑cell multiphasic insulin response model to calculate insulin dosing and was compared to 3 days of open‑loop control. The closed‑loop system lowered mean plasma glucose from 160 to 71 mg/dl by 1 p.m., maintained fasting glucose near target, achieved 75 % of time in the 70–180 mg/dl range versus 63 % with open loop, and produced no severe hypoglycemia, demonstrating proof of concept for automated glycemic control.

Abstract

An automated closed-loop insulin delivery system based on subcutaneous glucose sensing and subcutaneous insulin delivery was evaluated in 10 subjects with type 1 diabetes (2 men, 8 women, mean [±SD] age 43.4 ± 11.4 years, duration of diabetes 18.2 ± 13.5 years). Closed-loop control was assessed over ∼30 h and compared with open-loop control assessed over 3 days. Closed-loop insulin delivery was calculated using a model of the β-cell’s multiphasic insulin response to glucose. Plasma glucose was 160 ± 66 mg/dl at the start of closed loop and was thereafter reduced to 71 ± 19 by 1:00 p.m. (preprandial lunch). Fasting glucose the subsequent morning on closed loop was not different from target (124 ± 25 vs. 120 mg/dl, respectively; P > 0.05). Mean glucose levels were not different between the open and closed loop (133 ± 63 vs. 133 ± 52 mg/dl, respectively; P > 0.65). However, glucose was within the range 70–180 mg/dl 75% of the time under closed loop versus 63% for open loop. Incidence of biochemical hypoglycemia (blood glucose <60 mg/dl) was similar under the two treatments. There were no episodes of severe hypoglycemia. The data provide proof of concept that glycemic control can be achieved by a completely automated external closed-loop insulin delivery system.