Closed-loop insulin delivery system shows better results for blood sugar control in type 1 diabetes

New research presented at this year's annual meeting of the European Association for the Study of Diabetes (EASD) in Berlin, Germany, and published in The Lancet, shows that use of a hybrid day-night closed-loop insulin delivery system is better than sensor-augmented pump therapy for blood sugar control in poorly controlled type 1 diabetes. The study, funded by JDRF, is by Dr Roman Hovorka, University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, UK, and colleagues.

Sensor-augmented pump therapy combines the technology of an insulin pump with a continuous glucose monitoring sensor that transmits glucose readings to the person wearing the device. In such systems, the person wearing the device is responsible for making all insulin-dosing decisions.

Closed-loop insulin delivery systems (also known as 'artificial pancreas' systems) take the technology to the next level by integrating continuous glucose monitoring with an insulin pump and an algorithm which automates insulin delivery. Hybrid closed-loop systems are characterized by the coexistence of automated insulin delivery (via the algorithm) and user-initiated insulin delivery, for example, providing mealtime boluses. In 2017, the first hybrid closed-loop system entered clinical use based on a safety non-randomised single-arm pivotal trial.

The study randomly assigned subjects (44 male, 42 female) with type 1 diabetes aged six years and older (oldest patient 65 years) treated with insulin pump and with sub-optimal blood sugar control (glycated haemoglobin HbA1c 7·5% to 10%) to receive either hybrid closed-loop therapy (N=46; patients) or sensor-augmented pump therapy (N=40; control) over 12 weeks of unrestricted living. Training on insulin pump and continuous glucose monitoring took place over a 4-week run-in period during the study.

The proportion of time that glucose was in target range between 3·9 and 10·0mmol/l was significantly higher in the closed-loop group (65%) compared to control group (54%). In the closed-loop group, glycated hemoglobin (HbA1c --a measure of recent average blood glucose control) was reduced from a screening value of 8·3% to 8·0% post-training and 7·4% after the study. In control group these values were 8·2%, 7·8% and 7·7%; reductions in HbA1c levels were significantly greater in closed-loop group compared to control group (mean difference in change 0·36%).

The time spent with glucose levels below 3·9mmol/l (very low blood sugar or hypoglycemia) was a median of 12 minutes was lower in the closed-loop group; and the time spent above 10·0mmol/L (hyperglycemia) was a median of 2 hours 24 minutes lower in the closed-loop group. The proportion of time spent in these dangerous conditions overall was 3.5% median at baseline in the closed-loop group which fell to a median of 2.6% following the study. In the sensor-augmented pump group this increased from 3.3% at baseline to 3.9% after the study.

Total daily insulin dose was not different and body weight change did not differ significantly between the groups. No severe hypoglycemia occurred, however one diabetic ketoacidosis occurred in the closed-loop group due to infusion set failure.

The authors conclude: "The use of day-and-night hybrid closed-loop insulin delivery improves glycaemic control while reducing the risk of hypoglycemia in adults, adolescents and children with type 1 diabetes compared to conventional pump therapy or sensor-augmented pump therapy. Results from our study together with those from previous studies support the adoption of closed-loop technology in clinical practice across all age groups."

"Dr Hovorka's study is significant in that it adds to the ever-growing body of evidence showing that closed-loop insulin delivery systems improve outcomes and reduce burden for people with type 1 diabetes," said Daniel Finan, Research Director at JDRF, who supported the study. "In particular, this study demonstrates that people with diabetes who have sub-optimal control can benefit greatly from such technology."

Rachel Connor, Director of Research Partnerships at JDRF in the UK (who supported the study), said: "These are great results. I congratulate Professor Hovorka on the vital work he is doing. Type 1 diabetes is a challenging condition, but these results take us a step closer to changing the lives of the millions of people that live with the condition across the world."