Understanding and improving individual responses to exercise training for those at risk for, or living with, type 2 diabetes mellitus

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University of New Brunswick


Background: Prediabetes and type 2 diabetes mellitus (T2DM) are highly prevalent chronic diseases. Exercise is recommended to improve glycemic control and prevent progression from prediabetes to T2DM. However, a significant proportion of individuals do not experience the desired benefits (referred to as non-responders). Currently, there are a number of recommended methods, conflicting theories, and many unanswered questions associated with individual exercise response research. Two of the most pertinent questions are how to best implement these methods and interpret the results in a clinical setting, and what to do once an individual is determined to be a non-responder. Aims: 1) Use currently recommended methods to identify if prescribing high intensity exercise to youth at risk of T2DM increases the likelihood of experiencing the targeted benefits (responding) to exercise, and; 2) Investigate if increasing exercise intensity can be used as a method to adapt an exercise prescription to improve the response categorization for individuals living with prediabetes or T2DM who were previously identified as non-responders. Methods: The dissertation is broken into two studies: (1) An analysis calculating the influence of exercise on response heterogeneity for cardiometabolic risk factors in youth at risk of T2DM. Subsequently, the proportion of responders for each risk factor was estimated; and (2) A randomized trial identifying non-responders among individuals living with prediabetes or T2DM, prior to exploring if increasing exercise intensity would improve the response categorization for non-responders. Results: We found the proportion of youth estimated to respond spanned from 36% to 69%, depending on the intensity of exercise and the outcome of interest. Moreover, it was found that maintaining and increasing the intensity of exercise is capable of improving the response categorization of a small number of participants, although the likelihood of success is small. Conclusion: This dissertation outlined the influence of exercise on response heterogeneity. The inconsistent response to exercise training was brought to light and for the first time discussed in the context of T2DM. Moreover, a unique attempt to improve the response categorization of individuals categorized as non-responders provided an outline for how to transition these methods to a clinical setting.