Closed-loop system releasing glucagon helps with hypoglycemia in exercise, study suggests

A closed-loop system that delivers insulin as well as glucagon and detects exercise has been shown to reduce hypoglycemia (low blood sugar) in adults with type 1 diabetes.
US researchers believe the findings are significant because while automated insulin delivery is becoming more common in type 1 diabetes, managing exercise-related hypoglycemia remains a concern.
A study team from the Oregon Health and Science University in Portland hypothesised that the addition of glucagon could address this. An existing dual hormone system called the iLet, known as the bionic pancreas, has already shown to be able to reduce hypos.
The researchers enrolled 20 physically active adults with type 1 diabetes to receive randomised treatment over four days. The four treatments were dual hormone (insulin as well as glucagon), single hormone (just insulin), predictive low glucose suspend, and continuation of their current care.
Their dual hormone system involved a Dexcom G5 continuous glucose monitoring system (CGM), a Google Nexus Phone and a t:slim insulin pump.
In each treatment group, participants were tasked with completing three moderate-intensity aerobic exercise sessions.
The lowest mean time spent in hypoglycemia during the exercise period was seen in the dual hormone treatment, as well as during the entire four-day study.
“Exercise is challenging to manage in type 1 diabetes, partly because there are many types of exercise to consider and each type affects glucose metabolism in different ways,” said the authors.
“Here we describe a novel automated exercise-enabled dual-hormone closed-loop system that outperformed an exercise-enabled single-hormone system and a predictive low glucose suspend system in hypoglycemia reductio, demonstrating the value of glucagon in glucose management during exercise.”
The researchers added that because some participants experienced nausea, glucagon delivery may need to be timed earlier in supplementary studies before exercise and at a lower dose to reduce the risk of adverse effects.
The findings appear online in Diabetes Care.