Continuous glucose monitoring during competitive exercise

Abstract

Exercise is one of the cornerstones of diabetes treatment for both type 1 and type 2 diabetes (T1D/T2D), but the biggest barrier to doing so is the fear of hypoglycemia. Continuous glucose monitoring (CGM) has been available for several years, but it wasn't until 2020 that a consensus on CGM and exercise was drafted. This consensus considered variables to determine the safe glucose level for starting exercise, such as experience with exercise, perception of hypoglycemia, severe hypoglycemia in the last 6 months, and time spent below target range. This allows for more personalized guidance. In addition, it takes into account whether exercise tends to lower or raise blood glucose levels, considering not only before and during exercise but also post-exercise and nighttime alerts, again taking into account individual risk of hypoglycemia.

While the benefits are numerous, we know that exercise increases the MARD (Mean Time Between Decreases), and the biggest difference lies not in the type of exercise, but in the difference between rest and exercise. Therefore, at certain times, it's necessary to check capillary blood glucose levels to make informed decisions, especially during competition.

In recent years, both high and low glucose alarms have helped people be more vigilant. The ability to predict low glucose levels before they occur provides reassurance and has not been shown to increase the burden of diabetes management.

While CGM (Continuous Glucose Monitoring) is generally safe, there are several sporting situations that require different precautions, such as high-altitude sports, water sports, and even, at times, contact sports, where special protective gear may be needed.

CGM becomes especially important after exercise to prevent hypoglycemia and ensure adequate carbohydrate replenishment, which is crucial during competition. Technological advances in glucose monitoring (GGM) and exercise tracking (e.g., power meters and heart rate monitors) allow for readily available measurements of factors related to glycemic control and exercise behavior, independent of the training or competition context and environment.