Open Collections

Abstract

Problem: Exercise improves glycemic regulation and lowers mortality risk in type 2 diabetes (T2D). However, knowledge gaps persist regarding how exercise quality and quantity impact glycemic regulation, especially in real-world settings. Similarly, while a single bout of exercise is known to enhance glycemic regulation, its magnitude and sustainability outside controlled environments require further investigation. Aims: This dissertation aims to: i) examine the effects of different types, intensities, and patterns of exercise on glucose homeostasis (Studies 1, 2 and 3) and ii) evaluate the feasibility of free-living blood collection and delivery for assessing glucose regulation in a real-world exercise intervention (Study 4). Methods: Three of the four studies (Studies 1,2,4) of this PhD utilized data from a large (n=120), multi-site pilot randomized controlled trial investigating a 26-week mHealth exercise intervention. These studies examined how different exercise parameters (duration, volume, intensity, consistency) influenced glycemic regulation across the 26-week exercise intervention, investigated if there were differences in glycemic regulation on exercise vs. non-exercise days in a real-world setting, and assessed the feasibility of remote blood collection to measure glucose regulation across the Canada-wide intervention. Study 3 was an analysis of a semi-randomized acute cross-over study and explored if different patterns of high-intensity interval training (HIIT) impacted beta-cell function and insulin sensitivity - the key physiological determinants of glucose regulation. General Conclusions: Average exercise duration and total exercise accumulated during the first 13 weeks of the 26-week intervention predicted HbA1c, SD and mean 24-hour glucose at the end of the 26-week exercise intervention. In this real-world setting, individuals living with newly diagnosed T2D had improved glycemic regulation in the 24-hour period after a bout of exercise as compared to days when they did not perform exercise. In a laboratory setting, an acute bout of 4 X 4-minute or 10 X 1-minute HIIT improved beta-cell glucose sensitivity in females living with T2D when compared to a seated control condition. As part of an exercise intervention in T2D, it appeared feasible for a diverse group of participants from across Canada to collect capillary blood and return by mail for remote assessment of glucose regulation via HbA1c.