If a “closed-loop control” insulin delivery system can overcome the challenges involved in skiing, it bodes well for everyday blood glucose control in people with type 1 diabetes.
That’s the presumption behind a study published online August 30 in Diabetes Care by Marc D Breton, MD, of the Center for Diabetes Technology at the University of Virginia, Charlottesville, and colleagues.
“Closed-loop control,” also known as “artificial-pancreas” systems, involve the pairing of a continuous subcutaneous insulin infusion pump and a continuous glucose monitor (CGM) with an algorithm that automatically adjusts insulin infusion in real time.
In the randomized, controlled trial of 32 youths (aged 10–16 years) with type 1 diabetes, a remotely monitored closed-loop control system improved glycemic control and reduced hypoglycemia during skiing, surmounting the “unique metabolic challenges” presented by the sport, including “intense prolonged physical activity, cold, altitude, and stress/fear/excitement,” Dr Breton and colleagues write.
The adolescents were randomized to either full use of the University of Virginia’s proprietary closed-loop system called the Diabetes Assistant (DiAs) or a CGM-augmented insulin-pump system. All subjects used the DiAs linked to their CGM for remote monitoring and alerts, but only in the treatment group was it connected to the insulin pump to control insulin delivery, while those in the control group manually adjusted their insulin delivery levels as usual.
Participants in the two groups were roughly matched for age and HbA1c level.
All of the subjects were experienced insulin-pump users, with a mean baseline HbA1c of 8.5% (range, 6.6%–13.2%). But not all were snow sport experts: 14 had no experience in either skiing or snowboarding, two were beginners, five were intermediate, and 11 were advanced skiers/snowboarders. These variables didn’t differ between the two treatment groups.
The study took place during 5-day camp visits at two US ski resorts in Virginia and Colorado, during which they skied for 5 to 6 hours each day.
Closed-Loop Cuts Hypoglycemia
The percentage of time spent between the target glucose range of 70 and 180 mg/dL over the entire week was 71.3% with the closed-loop vs 64.7% with the sensor-augmented pump (P = .008), amounting to an additional 1 hour and 40 minutes in range per day. The effect held during the daytime (P = .008) but didn’t differ overnight or during skiing (P = .156 and .604, respectively).
Average glycemia didn’t differ either overall or at any time point including during skiing, when both groups had a mean glucose level of 165 mg/dL. But overall insulin use was significantly lower for the closed-loop group overall (P = .0001), during the entire daytime (P = .0001), and during skiing (P = .013).
The percentage time spent with glucose levels <70 mg/dL (hypoglycemia) was nearly halved overall with the closed-loop system (3.2% vs. 1.8%, P = .0001) and also lower both during the entire day and during skiing (P = .0001 and .042, respectively). However, the number of hypoglycemic events and the amount of rescue treatments weren’t significantly different between the groups.
Skiing Experience Matters
Several outcomes were significantly influenced by the participants’ prior level of skiing experience. For example, time spent in hypoglycemia was decreased much more among the beginners using the closed loop (from 3.5% down to 1.2%) compared with the advanced group (from 2.9% to 2.3%), with the more experienced skiers likely being more adept at adjusting settings and managing their risk in the control group, the authors suggest.
Interaction between ski level and closed-loop use was also seen in the amount of insulin delivered overall and during the day, with a 4% reduction in the beginner group vs a 32% reduction in the advanced skier group.
Thus, the benefit of closed-loop may differ between those who are more or less experienced skiers: for beginners, the main advantage would be preventing hypoglycemia, whereas for advanced skiers the system could act to automatically minimize both high and low blood glucose levels rather than relying on patients’ own calculations.
Dr Breton and colleagues also point out that the performance of the CGM systems in this study was lower than previously reported, with a mean absolute relative deviation of 18.9%. This could relate to the cold temperatures, which may have significantly interfered with the blood glucose meter measurements used as reference points.
“The heterogeneous patient population, exercise, and environment in this first-of-its-kind study presented formidable challenges for the [artificial-pancreas] system. These data will allow for future adaptation and potential individualization to more precisely control glucose,” the authors conclude.
The study was funded by grants from the National Institute of Diabetes and Digestive and Kidney Diseases, the University of Colorado Foundation, the Children’s Diabetes Foundation, and private donors. Dexcom provided the CGMs. Dr Breton reports personal fees from Dexcom, Merck, and the Epsilon Group, grants and personal fees from Roche, Sanofi, and Ascencia; grants from Senseonic; nonfinancial support from Novo Nordisk and Tandem, and other from TypeZero Technologies, outside the submitted work. He also has several relevant current and pending patents in conjunction with TypeZero Technologies. Disclosures for the coauthors are listed in the paper.
Diabetes Care. Published online August 30, 2017. Abstract
For more diabetes and endocrinology news, follow us on Twitter and on Facebook.
Tidak ada komentar:
Posting Komentar