Circadian Rhythm and Metabolic Effects of Exercise (HITMet)

Exercise has well-established metabolic benefits and is a preferred intervention for Type 2 diabetes prevention and management. Metabolic determinants of exercise such as skeletal muscle and whole-body substrate oxidation capacity, glucose tolerance and insulin sensitivity and adipose tissue fatty acid release all show circadian oscillations. These rhythms may promote substantially different responses depending on the time of day when exercise is performed.

This is an exploratory study aiming to determine whether exercise at specific times of day can amplify the beneficial effects on glycemia and metabolism in twi groups of individuals: those with normal glucose tolerance (NGT) or Type 2 diabetes (n=40 per group). The primary objective is to determine the glycemic response to an exercise bout at two distinct times of day, measured by continuous glucose monitoring, in men and women with NGT or Type 2 diabetes. The secondary aim is to identify specific metabolites which facilitate the strongest glycemic response to exercise by examining the whole-body and peripheral tissue metabolomic response to an exercise bout.

The primary goal of the study is to examine the glycemic and metabolic response to exercise within-group for participants with NGT or Type 2 diabetes. Further comparisons will be made between groups with NGT or Type 2 diabetes, across sexes, and by individual chronotype (determined by a standardized questionnaire) to examine the variation in the exercise response across these parameters.