Artificial Pancreas Systems for Diabetes Are Works in Progress

Miriam E Tucker

April 24, 2018

The currently marketed artificial pancreas system and those in development are efficacious and safe approaches for treating outpatients with type 1 diabetes, a new meta-analysis has found. 

Results from the systematic review and meta-analysis of 41 randomized controlled trials were published online April 18 in BMJ by Eleni Bekiari, MD, PhD, Aristotle University of Thessaloniki, Greece, and colleagues.

Artificial pancreas treatment, also known as closed-loop glucose control, involves the combination of an insulin pump, continuous glucose monitor (CGM), and control algorithm that enables the system to automatically deliver appropriate insulin doses. One investigational system also includes glucagon delivery.

In 2016, the US Food and Drug Administration approved Medtronic's MiniMed 670G, the first hybrid closed-loop system for use in patients with type 1 diabetes aged 14 years and older. 

"In view of all the available evidence from randomized controlled trials, artificial pancreas treatment significantly improves glycemic control while reducing the burden of hypoglycemia in outpatients with type 1 diabetes," Bekiari and colleagues write.

"Results are consistent for people using artificial pancreas systems unsupervised under normal living conditions, and for both single hormone and dual hormone systems," they add.

However, they also note that the current research evidence on artificial pancreas systems is limited by inconsistency in outcome reporting, small sample sizes, and short follow-up durations of trials.

And in an accompanying editorial, Norman Waugh, MB ChB, professor of public health medicine and health technology assessment at the University of Warwick, UK, and colleagues write, "Closed-loop systems can improve control overnight, and reduce the burden of self-management during the day by reducing frequent decisions on adjustments to insulin dose. However, we do not know whether these systems reduce the long-term complications of diabetes."

The editorialists, one of whom is a patient who uses an open-source artificial pancreas system, also note that "the overall evidence base is weak. Many trials in the review were of low quality. Type 1 diabetes is lifelong, but most trials are short — of 41 trials included, 30 lasted 7 days or less."

Time in Range Improved Across Studies

The 41 trials reviewed by Bekiari and colleagues included 1042 participants in outpatient settings with data for 45 comparisons (one trial was eliminated for lack of appropriate data). The primary outcome was percentage of time with sensor glucose level within normal range (3.9–10 mmol/L, 70–180 mg/dL).

Compared with controls, patients using artificial pancreas systems spent a significant 9.6% more time in normal range, or an additional 140 minutes, over 24 hours. The effect was greater, 15.2%, during the overnight period.

Time in hyperglycemia (glucose > 10 mmol/L, 180 mg/dL) was reduced by 8.5%, or about 2 hours, and time with glucose levels below 3.9 mmol/L (70 mg/dL) was 1.5% lower, or about 20 minutes less compared with control treatment.

The incidence of severe hypoglycemia was very low in both the artificial pancreas and control groups (just six and three episodes, respectively). 

The findings remained significant in sensitivity analyses that included only trials with low risk of bias, in unsupervised outpatient living conditions, and that had separate analyses of single- and dual-hormone systems. 

What's Needed Now? 

"Overall, our results reflect the progress made over recent decades of extensive research and development in artificial pancreas use," say Bekiari and colleagues.

But they also point out that their meta-analysis "highlights some pitfalls in the conduct and reporting of artificial pancreas trials," including short duration and wide variation in outcomes reporting and metrics used, which they advise research groups standardize in consultation with relevant stakeholders including clinicians and patients.

More trials in children and cost-effectiveness data are also necessary, they say. 

Waugh and colleagues note that none of the 17 trials in children or adolescents in the review included children younger than 5 years, "a group in which closed-loop technology might reduce parental anxiety about nocturnal hypoglycemia."

"We need longer and larger trials, in both adults and children, to compare closed-loop systems with self-management using continuous glucose monitoring. These trials should measure HbA1c (for modeling the effects on complications), blood glucose variability, hypoglycemia, quality of life, and cost effectiveness," they add.

"Manufacturers need not look for complete automation. People with type 1 diabetes will remain involved in management. But closed-loop systems, as well as open-loop systems with data acted on by the user, could reduce the burden," they conclude.

The study was funded by the Aristotle University Research Committee, National Institute for Health Research Cambridge Biomedical Research Centre, and Wellcome Strategic Award. Bekiari has reported no relevant financial relationships. Waugh has advised Novo Nordisk on matters unrelated to the current topic.

BMJ. Published online April 18, 2018. Full text, Editorial

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