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Artificial pancreas improves glucose control

People using closed loop system less prone to overnight hypos and hypers

Louise Prime

Thursday, 18 September 2014

New closed-loop insulin delivery systems have shown they can improve overnight glucose control, in two UK studies* in adolescents and adults with type 1 diabetes. The results are being presented today at the European Association for the Study of Diabetes’ annual meeting in Vienna, and the researchers behind the trials said they’d shown that an artificial pancreas is a feasible way of cutting the risk of nocturnal hypoglycaemia.

They set up two home-based unsupervised randomised open-label crossover studies to compare two systems. One was overnight closed loop therapy using an ‘artificial pancreas’, so-called because the system self-measures glucose levels in the interstitial fluid and administers the appropriate insulin dose without patients’ input. The second was sensor augmented pump therapy, in which the patient uses information from the sensor to manually adjust the pump.

The researchers recruited 24 adults and 16 adolescents with type 1 diabetes, whose mean age was 43 years and average HbA1c 8.0%, and trained them in using the study devices. Patients then had two periods of sensor augmented pump therapy in combination with or without a overnight closed-loop system, each period lasting three or four weeks, in random order. In all, closed loop was used on 866 nights which equates to 7,619 hours’ use of closed loop at home, without supervision or remote monitoring.

Compared with sensor augmented therapy, people using the closed loop system spent 18% longer between midnight and 8:00a.m. with their blood glucose in the target range (3.9-8.0mmol/l). They also had a significant, 0.8mmol/l reduction in mean overnight glucose, with no difference in glucose variability; this was achieved as a result of higher overnight insulin delivery, but without changing the total daily insulin delivery. While using the closed loop system, people spent less time in either hyperglycaemia or hypoglycaemia, compared with sensor augmented therapy.

The study authors concluded: “Unsupervised overnight closed loop delivery at home in adults and adolescents with type 1 diabetes is feasible, demonstrating improvements in glucose control and reducing the risk of nocturnal hypoglycaemia.

“The next decade will see closed loop systems progressively entering clinical practice and helping in the management of type 1 diabetes. Our current priority is to demonstrate benefits of closed loop systems when used over several months and in various sub-populations.”

* Thabit H, Leelarathna L, Elleri D, et al. Three to four weeks of overnight closed loop insulin during free living: analysis of randomised crossover studies in adults and adolescent with type 1 diabetes.

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