MELBOURNE – A closed-loop system of continuous glucose monitoring coupled with an insulin pump significantly improved glucose control in adolescents with type 1 diabetes, with less time spent in hypoglycemia.
In a real-world, at-home study of the so-called artificial pancreas, 24-hour mean glucose levels were significantly lower among patients using the closed-loop device (8.5 mmol/L), compared with those using sensor-augmented pump therapy (9.0 mmol/L).
Dr. Roman Hovorka
The closed-loop system also led to significantly more time in blood glucose targets (64% vs. 47%) and fewer nights with hypoglycemia (10% vs. 17%) over 21 days, Roman Hovorka, Ph.D., said at the World Diabetes Congress.
The randomized crossover trial enrolled 16 individuals with type 1 diabetes who had a mean age of 15.4 years. Subjects were trained in use of the device, and there was a 2- to 3-week washout period between crossovers.
Dr. Hovorka, director of research at the University of Cambridge (England) Metabolic Research Laboratories, said that 5 years of research had demonstrated the utility, safety, and efficacy of the closed-loop system in the clinical research facility setting, and now this study had shown it in the home setting against a sensor-augmented pump.
The artificial pancreas consists of a continuous glucose monitor that measures blood glucose every 1-5 minutes and transmits this information to a control algorithm, which instructs an insulin pump to release the required amount of insulin into the body.
"The algorithm is the brain and it mimics in principle what a beta cell would do in terms of reacting to glucose levels and secreting the right amount of insulin," Dr. Hovorka said in an interview.
"The advantage is that it’s glucose-responsive insulin delivery, which is what we need to achieve with glucose control," he added.
The study also showed that, while the closed-loop device delivered slightly more insulin at night (8.1 units vs. 7.2 units, P less than .001), 24-hour insulin was lower with the closed-loop device than with the pump (49.9 units vs. 53.2 units, P = .009), he said.
Researchers used off-the-shelf devices to build their artificial pancreas system, and while no single unit is yet available, several prototype devices are in development. Dr. Hovorka said that some groups also are looking at combining glucose sensing and insulin delivery into a single port.
Patients reported greater reassurance, confidence, and better sleep with the closed-loop system, although there were some issues with calibration of the system, size of the device, and discomfort.
Session chair Dr. Kavita Kumareswaran, consultant endocrinologist at the Baker IDI Heart and Diabetes Institute, Melbourne, said that the development of a closed-loop system was hugely important and patients were already asking when such a device was likely to become available.
"The biggest thing for patients is their fear of hypoglycemia, so that’s where the biggest utility will be, particularly overnight where they’re asleep and can’t check their sugars. That’s where the greatest benefit will be," Dr. Kumareswaran said in an interview.
The researchers declared research support from Minimed Medtronic, Abbott Diabetes Care, Animas, and Edwards Lifesciences, as well as advisory panel memberships and speakers’ engagements for other pharmaceutical and medical device companies.