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Automated exercise detection with dual-hormone artificial pancreas system may reduce hypoglycemia
SAN DIEGO — Incorporating an exercise detection function into a dual-hormone closed-loop glucose control system may help users with type 1 diabetes avoid exercise-induced hypoglycemia.
“Many people with type 1 diabetes don’t exercise ... and the reason for that is the fear of hypoglycemia,” Peter G. Jacobs, PhD, assistant professor in the department of biomedical engineering at Oregon Health and Science University in Portland, said during a presentation.
Jacobs and colleagues conducted a study to “try to use automated insulin and glucagon delivery systems to help alleviate the risk of exercise-induced hypoglycemia,” he said.
The study included 20 who were assigned to an exercise regimen under four different device conditions in random order: a single-hormone closed-loop system that delivered insulin; a dual-hormone closed-loop system that delivered insulin and glucagon; a predictive low-glucose suspend system that automatically cut off insulin delivery in response to an algorithm; and the participant’s usual method of glucose control.
During the 4-day exercise regimens, participants exercised at the study site for 45 minutes at 60% of peak oxygen uptake on days 1 and 4, rested on day 2 and exercised at home on day 3. In both closed-loop systems, a Zephyr heart rate monitor and accelerometer detected exercise and signaled for insulin cut-off for 30 minutes followed by 50% insulin reduction for 60 minutes; in the dual-hormone system exercise detection also signaled the increase of glucagon by 200% for 1.5 hours. A Dexcom G5 sensor sent glucose levels every 5 minutes to a Google Nexus phone running the closed-loop algorithm. Delivery commands were sent every 5 minutes to Tandem t:slim pumps for insulin and/or glucagon infusion. Capillary blood glucose levels were measured four times per day.
Jacobs presented preliminary results from 17 visits in this subgroup of participants. The dual-hormone group spent the least amount of time in hypoglycemia (< 70 mg/dL): 1% vs.
43.4% for the single-hormone group, 1.2% for the predictive low-glucose suspend group and 2.1% for the current care group. He noted that the current-care participants avoided hypoglycemia by strategically keeping their blood glucose levels significantly higher before exercise. Post-exercise mean glucose level was significantly lower for the single-hormone group (67 mg/dL) vs. the dual-hormone group (100 mg/dL).
“The automated glucagon we generally found reduces exercise-induced hypoglycemia, compared with single-hormone and predictive low-glucose suspend systems,” Jacobs said. “We find that the wearable activity trackers can be used to inform an artificial pancreas; they are able to detect exercise successfully in 85% of the participants. We found that both dual- and single-hormone artificial pancreases can increase the time spent in euglycemia compared to a predictive low-glucose suspend system. In the future, I think that front-loading the glucagon may help reduce [hypoglycemia] even further.” – by Jill Rollet
Reference:
Jacobs PG. 97-OR. Presented at: American Diabetes Association 77th Scientific Sessions; June 9-13, 2017; San Diego.
Disclosure : The study was funded by NIH; Dexcom and Tandem provided technology for the study. Jacobs reports holding stock in Pacific Diabetes Technologies.