February 21


How a Closed-Loop Insulin Delivery Handles Unannounced Exercise

By Gabriela

February 21, 2022

A group of researchers from Slovenia conducted a study on a closed-loop insulin delivery system to discover how it deals with unannounced exercise. They saw that blood glucose levels remained mostly in the target range.

Low blood glucose levels are a concern to many those with type 1 diabetes during exercise. The purpose of this research was to see how efficient and safe this insulin delivery system is during spontaneous afternoon exercise and the next night in young people with this type.

But, the effects of exercise on blood glucose levels in people with type 1 continue even hours after exercise. Also, a lot of people have problems with low levels during the night.

Unannounced or spontaneous exercise can cause trouble to those with this type. These people usually need some preparation before engaging in physical activity. That could be taking glucose or giving insulin to keep blood glucose levels in a safe range during exercise.

So, could a closed-loop insulin delivery system be safe for these people? And could it keep their blood sugar levels in the normal range?

This insulin delivery system has a CGM (continuous glucose monitor) that communicates with an insulin pump which provides insulin based on a control algorithm.

More About the Study

Researchers conducted a two-arm, randomized, in-hospital, open-label, crossover clinical trial at a single site. There were 20 participants, teens, and children with type 1, who had experience in using insulin pumps.

Nine of them were female, all with an average A1c of 7.7%, and an average age of 14.

The participants participated in spontaneous moderate-intensity exercise as well as moderate-intensity exercise with integrated high-intensity sprints during 4 different in-hospital visits.

Researchers analyzed the blood glucose control of the participants during the exercise and the next night. The closed-loop insulin delivery was applied from 3 pm on the day of exercise to 1 pm the following day.

Is This Delivery System Beneficial?

According to researchers, there was not a single time that the participants from both groups, those who used open-loop and those with a closed-loop insulin delivery system, have blood glucose levels below 3.3 mmol/L (59 mg/dL).

But, they say the closed-loop system spent more time within the normal range of 3.9 mmol/L (70 mg/dL) and 10 mmol/L (180 mg/dL). This was in comparison with the open-loop insulin delivery. They say that was achieved with drastically less insulin passes on through the closed-loop.


The results showed that the closed-loop insulin delivery system safely and effectively kept blood sugar levels within the normal range during and after spontaneous exercise. What’s more, it didn’t increase the chances of hypoglycemia.


  • Gabriela

    Co-Founder & Editor-in-Chief of Diabetes Health Page, Fitness trainer and instructor has dedicated her career to educating and informing people for over 10 years. As one of the most passionate diabetes advocates, Gabi has worked tirelessly to ensure that those people receive the education and support they need to properly manage their diabetes and achieve their health, fitness and weight loss goals.

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