A fully closed-loop artificial pancreas system improved glucose control and reduced hypoglycemia compared with standard insulin therapy in adult outpatients with type 2 diabetes requiring dialysis, a small study shows.  

Findings from the open-label randomized crossover trial were published online August 4 in Nature Medicine by Charlotte K. Boughton, MD, PhD, of the University of Cambridge, UK, and colleagues.

Management of type 2 diabetes is particularly challenging in patients with end-stage renal disease (ESRD) who are receiving dialysis because both increase the risks of hypoglycemia and hyperglycemia. Insulin is commonly used in this population, as most oral glucose-lowering medications are contraindicated in ESRD. 

“The aim was to evaluate the safety and efficacy of this closed-loop system in a population where glycemic control is particularly challenging,” Boughton told Medscape Medical News.

Closed-loop insulin delivery systems, also known as an artificial pancreas, are comprised of a continuous glucose monitor (CGM), insulin pump, and control algorithm that continuously adjust insulin delivery in response to real-time interstitial glucose levels. These systems are increasingly used in type 1 diabetes. However, in type 2 diabetes, their use has been limited to the inpatient setting in certain patient groups, including those on hemodialysis. Boughton’s group had previously reported success with use of the systems in that setting.

System Added 3.5 Hours Per Day to Time Spent in Range

The current study enrolled 26 patients with ESRD recruited from dialysis, nephrology, and diabetes outpatient clinics at Addenbrooke’s Hospital in Cambridge, UK, and Inselspital, University Hospital of Bern, Switzerland. There were 17 men and nine women, average age 68 years, and diabetes duration was 20 years.

Half of participants were randomized to closed-loop first and the other half to standard insulin therapy first for 20 days each of unrestricted living (including during dialysis), separated by 2-4 week washout periods.

The closed-loop system used the Cambridge adaptive model predictive control algorithm (CamAPS HX) and closed-loop app (CamDiab, Cambridge, UK). The app is on an unlocked Android phone and receives sensor glucose data from a Dexcom G6 transmitter, which directs insulin delivery on a Dana Diabecare RS pump (Diabecare, Sooil, South Korea). The algorithm uses sensor data to adjust the insulin infusion rate every 8 to 12 minutes. The system used faster-acting insulin aspart (Fiasp, Novo Nordisk).

The primary endpoint, the proportion of time sensor glucose in target glucose range of 5.6-10.0 mmol/L (100-180 mg/dL), was 52.8% during the closed-loop versus 37.7% for the control period (P < .001). There were no significant differences in those values across the two time periods.

Mean glucose was 1.5 mmol/L (27 mg/dL) lower with the closed-loop, while time spent in hypoglycemia was reduced (P = .04). With algorithm adaptation, time in range improved from 36% on day 1 to over 60% by the end of the 20-day period.

Overall, fully closed-loop insulin delivery added 3.5 hours per day spent in target glucose range compared with standard insulin therapy. CGM consensus guidelines recommend a time in range > 50% in older adults or more vulnerable/high risk populations, Boughton noted.

Only one episode of severe hypoglycemia occurred during the closed-loop period, but the closed-loop actually wasn’t in operation at the time of the event or in the prior 24 hours. Five other serious adverse events were reported but none were deemed related to the study devices.

Of 24 patients who completed questionnaires at the end of the study, all reported that they were happy to have their glucose levels controlled automatically by the closed-loop system and would recommend it to others.

The CamAPS HX system is currently licensed in the UK for people with type 2 diabetes in the inpatient, but not outpatient, setting. It is designed to be interoperable in the future with connectivity to a variety of different insulin pump and CGM devices. A hybrid-closed loop system, the CamAPS FX, is also licensed in the UK for people with type 1 diabetes. The term “hybrid” closed-loop refers to the need for meal “announcements” with the CamAPS FX but not with the “fully closed-loop” CamAPS HX.   

The Cambridge team currently has an active study using the same closed-loop system in patients with type 2 diabetes not requiring dialysis, Boughton told Medscape Medical News.

Supported by the National Institute for Health Research Cambridge Biomedical Research Centre. Dexcom supplied discounted CGM devices and sensors for the study; company representatives had no role in the study conduct. Boughton was supported by a grant from the Novo Nordisk UK Research Foundation.

Nature Med. Published online August 4, 2021. Full text

Miriam E. Tucker is a freelance journalist based in the Washington, DC, area. She is a regular contributor to Medscape, with other work appearing in the Washington Post, NPR’s Shots blog, and Diabetes Forecast magazine. She is on Twitter @MiriamETucker.

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