Closed-loop insulin delivery improved glucose control, reduced hypoglycemia risk for children

An artificial pancreas closed-loop insulin system led to greater reductions in the risk for nocturnal hypoglycemia when compared with continuous subcutaneous insulin infusion in children and adolescents with type 1 diabetes, according to a new study published in the Lancet.

Researchers assessed whether insulin delivery via a closed-loop system reduced the risk for nocturnal hypoglycemia in 17 children aged 5 to 18 years with type 1 diabetes (6.4 years duration). All children were enrolled in three studies of the Wellcome Trust Clinical Research Facility at Addenbrooke’s Hospital in Cambridge, United Kingdom, from April 2007 to September 2008.

Standard continuous insulin infusion and closed-loop delivery (n=13) were compared with closed-loop delivery after rapidly and slowly absorbed meals in seven patients, and closed-loop delivery vs. standard treatment after exercise in 10 patients. Children were randomly assigned to either plasma glucose or sensor glucose.

Primary outcome measures were time of plasma glucose concentration between 3.91 mmol/L to 8 mmol/L or <3.9 mmol/L. Seventeen patients were followed for 33 nights of closed-loop insulin and 21 nights of continuous insulin delivery.

The researchers reported no significant differences in primary outcomes between the treatment groups.

Children who were assigned to the closed-loop system maintained blood glucose levels in the normal range for 60% of the time vs. those assigned to the continuous subcutaneous insulin pump who were in the normal range for only 40% of the time (P=.0022). In addition, glucose concentrations were <3.9 mmol/L for 2.01% of the time in those assigned to closed-loop insulin delivery vs. 4.1% of the time in those assigned to continuous insulin delivery (P=.0304).

In addition, the closed-loop system prevented blood glucose from decreasing <3 mmol/L when compared with nine events in those assigned to continuous insulin delivery.

Transforming management of type 1 diabetes

“Closed-loop systems could transform management of type 1 diabetes, but their introduction is likely to be gradual, starting from straightforward applications … proceeding to more complex applications providing 24-hour control,” the researchers wrote.

In an accompanying editorial, Eric Renard, MD, PhD, of the Centre Hospitalier Universitaire de Montpellier, France, discussed the various technological issues surrounding closed-loop insulin delivery.

“Starting with overnight control before addressing control at meal times and during various activities is the most rational way forward,” he wrote. “This seems to be the track to follow toward progressive implementation of automated insulin delivery at home.”

The study was funded by the Juvenile Diabetes Research Foundation, European Foundation for the Study of Diabetes, Medical Research Council Centre for Obesity and Related Metabolic Diseases and the National Institute for Health Research Cambridge Biomedical Research Centre.

Hovorka R. Lancet.2010;doi:10.1016/S0140-6736(09)61998-X.