Closed loop systems are associated with better glycaemic control compared to other treatments in people with type 1 diabetes but there’s still a lot we don’t know, a review of the latest evidence reveals.

The systematic review published in The BMJ that involved 41 studies found that an “artificial pancreas” was associated with almost two and a half additional hours in near normoglycaemia over a 24 hour period compared with other  standard treatments.

The researchers led by Eleni Bekiari from Aristotle University of Thessaloniki in Greece said this finding was mainly due to the favourable effects of closed loop systems on overnight glycaemia. They said this finding was verified by its effect on time in hyperglycaemia (two hours less than control treatment) and in hypoglycaemia (20 minutes less).

“Overall, our results reflect the progress made over recent decades of extensive research and development in artificial pancreas use,” the authors wrote.

However, they said their study highlighted some pitfalls of trials conducted in the area. Some were limited by small sample size, short follow-up, or were testing feasibility or safety rather than long term effectiveness.

Future trials should clarify the differences between single hormone and dual hormone systems and explore the use of closed loop systems in type 2 diabetes, such as those with inpatient hyperglycaemia. Their effect on quality of life and reducing patient burden should also be explored.

Writing in a linked editorial Professor Norman Waugh and colleagues at the University of Warwick in the UK argued that while closed loop systems can improve control overnight, and reduce the burden of self-management during the day, it was not known whether they reduced the long term complications of diabetes.

“For policy makers, there are insufficient data for cost effectiveness analysis. We need longer and larger trials, in both adults and children, to compare closed loop systems with self-management using continuous glucose monitoring,” the editorialists wrote.

“These trials should measure HbA1c (for modelling the effects on complications), blood glucose variability, hypoglycaemia, quality of life, and cost effectiveness,” they said.