Adults with diabetes type 1 who use an artificial pancreas – closed loop insulin delivery – may have better blood glucose control during sleep and a lower risk of glucose levels suddenly plummeting during the night (hypoglycemia), researchers from the University of Cambridge, England, revealed in the BMJ (British Medical Journal).

Diabetes type 1 incidence is growing at 3% per year, the authors wrote, and at a higher rate among people of northern European origin.

Patients with diabetes need insulin therapy to control blood sugar levels for life. However, hypoglycemia risk, especially during the night, is something most patients constantly fear.

Closed loop insulin delivery systems these days automatically work out the insulin doses required according to feedback from a sensor. According to prior studies, this artificial pancreas works well with children and teenagers. However, until this study was done, nobody knew how effective it might be with adults.

Roman Hovorka and team set out to compare the efficacy and safety of overnight closed loop insulin delivery against using a conventional insulin pump for individuals with diabetes type 1.

They carried out two studies on 24 adults – 10 males and 14 females, aged between 18 and 65. They had all been using insulin pump therapy for a minimum of three months.

  • First study – the first twelve patients were monitored during the night two times. They had eaten a 60g carbohydrate meal at 7pm. The authors classed this as a medium sized meal. They were randomly selected to use either a conventional insulin pump or closed loop delivery of insulin. Three weeks later the same happened again, but those who had used one therapy system this time used the other.
  • Second study – the other 12 patients were monitored during the night two times after eating a 100g carbohydrate meal at 8.30pm. They also consumed alcohol during their meal. They were randomly assigned either the conventional insulin pump or closed loop delivery of insulin.

Those on the loop insulin delivery spent 28% longer within their blood glucose target range. The investigators also observed that closed loop delivery also reduced glucose variability during the night and considerably reduced the time patients spent hypoglycemic.

The authors believe their studies provide further evidence demonstrating the safety and efficacy of overnight closed loop delivery across a wide range of insulin sensitivities, lifestyle conditions, and age groups.

The researchers wrote:

(the closed loop system) “may in future allow more flexible lifestyles in conjunction with improved glycaemic control for people with type 1 diabetes.”

Professor Boris Kovatchev, from the University of Virginia said that in a research setting the loop control looks promising. Further development and system miniaturization is required in practice to significantly improve the health and quality of life of patients with diabetes type 1.

“Overnight closed loop insulin delivery (artificial pancreas) in adults with type 1 diabetes: crossover randomised controlled studies”
Roman Hovorka, Kavita Kumareswaran, Julie Harris, Janet M Allen, Daniela Elleri, Dongyuan Xing, Craig Kollman, Marianna Nodale, Helen R Murphy, David B Dunger, Stephanie A Amiel, Simon R Heller, Malgorzata E Wilinska, Mark L Evans
BMJ 2011; 342:d1855 doi: 10.1136/bmj.d1855

Written by Christian Nordqvist