Type 1 diabetes

Hybrid closed loop systems cope well with exercise


Use of hybrid closed loop (HCL) significantly improves time-in-range compared to standard therapy in adults with type 1 diabetes, even in patients undertaking moderate or high intensity exercise, Australian research shows.

A substudy of a larger and previously published HCL study involved 10 patients, randomised to either HCL (MiniMed™ 670G system) or standard therapy with self-monitoring of blood glucose with management by MDI or CSII.

Patients undertook either 45 minutes of moderate intensity exercise or high-intensity interval exercise separated by seven days.

The study, published in the Journal of Diabetes Science and Technology, found that when combining both forms of exercise HCL significantly improved time-in-range 0 to 24 h post-exercise commencement (69.7% v 46.5%; P=.033).

For moderate exercise, 0-24 h and 0-2 h time-in-range was greater for HCL than standard therapy.

There were no differences between HCL and standard therapy in ketones, lactate, cortisol, adrenaline, noradrenaline, and dopamine with moderate or high intensity exercise, and time-below-range was lower for HCL.

One HCL participant experienced hypoglycaemia during moderate exercise and one within 120 minutes of moderate exercise. There were no episodes of severe hypoglycaemia or other serious adverse events.

“In conclusion, relative to standard therapy during MIE and HIIE and up to 24 h post exercise, HCL use significantly improves time-in-range by 23% with no increase in hypoglycaemia,” the study said.

Glucose levels and exercise

Lead author Dr Barbora Paldus, from St Vincent’s Hospital Melbourne, told the limbic the study was important to show the HCL system could cope with the unique physiological changes that can occur during exercise.

“For example, during moderate intensity exercise glucose levels tend to drop whereas during high intensity exercise, glucose levels can actually increase due to a rise in various hormones.”

“With various other types of exercise where you have got a mix of intensities – for example, a soccer game with sprinting and moderate intensity running – people’s sugars can go up or down. So exercise can be really quite tricky for people with type 1 diabetes to manage.”

She noted some people with T1D may be reluctant to exercise because they are concerned about hypos or glycaemic variability.

“The point of the study was to see if the HCL works well during exercise and can cope with the changes.”

Dr Paldus said that despite the limitation of a small study, their findings were positive and consistent with other studies in exercise.

“In free living situations the result might be a bit different and that’s why we’d like to see future studies in the real world with unplanned exercise.”

She said the HCL systems were continually improving.

“In the future the final aim is to get a system which is completely automated where you don’t have to enter carbohydrates or announce exercise, you can just go on with your life. That’s the aim and what these studies are looking towards.”

“We are trying to make it easier in terms of allowing people with type 1 diabetes to exercise without worry. If we can make life easier and type 1 diabetes not so burdensome, that’s the ultimate goal for these technologies.”

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