Feasibility of closed-loop insulin delivery in type 2 diabetes: a randomised controlled study

  1. Dr Roman Hovorka, PhD1
  1. 1University of Cambridge Metabolic Research Laboratories and NIHR Cambridge Biomedical Research Centre, Hills Road, Cambridge, CB20QQ, UK
  1. Corresponding author: Roman Hovorka, E-mail: rh347{at}


Objective Closed-loop insulin delivery offers a promising treatment option, but to date has only been evaluated in type 1 diabetes. Our aim was to evaluate feasibility of fully closed-loop using subcutaneous insulin delivery in insulin-naïve type 2 diabetes.

Research Design and Methods Twelve subjects (7 males, age 57.2y, BMI 30.5 kg/m2) with non-insulin treated type 2 diabetes (HbA1c 8.4% [68 mmol/mol], diabetes duration 7.6y) underwent two 24-hour visits (closed-loop and control) in a randomised crossover design. During closed-loop visits, subjects’ routine diabetes therapy was replaced with model predictive control algorithm-driven subcutaneous insulin pump delivery, based on real-time continuous glucose monitoring. Meals were unannounced and no additional insulin was administered for carbohydrates consumed. During control visits, usual diabetes regimen was continued (metformin 92%, sulfonylureas 58%, DPP-4 inhibitors 33%). On both visits, subjects consumed matched 50-80g carbohydrate meals and optional 15g carbohydrate snacks and remained largely sedentary. Plasma glucose measurements evaluated closed-loop performance.

Results Compared with conventional therapy, 24 hours of closed-loop increased overall median time in target plasma glucose (3.9-8.0 mmol/l) from 24% to 40% (p=0.016), despite sensor under-reading by median 1.2 mmol/l. The benefit of closed-loop was more prominent overnight with greater time in target glucose (median 78% vs. 35%; p=0.041), and less time in hyperglycaemia (22% vs. 65%; p=0.041). There was no hypoglycaemia during either intervention.

Conclusions A closed-loop system without meal announcement using subcutaneous insulin delivery in insulin-naïve type 2 diabetes appears feasible and safe. Improvement in postprandial glucose control may require further optimisation of system performance.

  • Received May 1, 2013.
  • Accepted August 18, 2013.

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