Effect of blood glucose level on sport skill performance

Playing sport is a complex combination of motor skill performance, cognitive processing and reaction time, all of which are influenced by blood glucose levels.

This study found sport skill performance in young athletes was highest when blood glucose levels were in the normal range. The greatest performance deficits were observed during concurrent hypoglycaemia. The authors suggested differences in level of impairment could be related to BGL concentration, BGL drop rate and individual capacity to maintain focus in light of these factors.Although the study did not find a sport skill deficit resulting from hyperglycaemia the authors cite other studies demonstrating cognitive impairment related to hyperglycaemia >20mmol/L. It was also suggested the failure of this study to observe relative decrements in sport skill performance may have been due to the transient nature of hyperglycaemic episodes where mean blood glucose concentrations were lower (16.9 ± 3.17 mmol/L).

Although not examined in this study the authors also suggested it would be likely for sport skill performance to decline if the level of hyperglycemia was higher and/or prolonged i.e., days rather than minutes to hours. In this scenario individuals would be expected to be suffering from dehydration, ketosis, and reduced muscle and liver glycogen content.

Take home message: These findings may seem obvious anecdotally however this research shows there is more to playing sport with T1D than simply getting by without suffering a major adverse event. And understanding type 1 diabetes management during sport is key to being able to compete on equal ground.

I have found this to be a great motivational tool for getting young people interested in better management.

Here’s an example: “Allan, your talk on diabetes and exercise was inspirational and a much needed morale booster. At the beginning of the evening it was the usual diabetes get together but after your talk the room was abuzz with excitement and the possibilities that you opened up to the families. One young man told me he never had a good reason to manage his diabetes better until now - the penny dropped that tighter diabetes control would help him perform better in Rugby. He didn’t have to chase his blood glucose up and down as much as he was doing.”
Kerry - Credentialled Diabetes Educator Orange NSW

Dylan K, Jill K, others. Blood Glucose Levels and Performance in a Sports Camp for Adolescents with Type 1 Diabetes Mellitus: A Field Study. International Journal of Pediatrics. 2010;2010. See full text article here.