Nana Wu’s PhD Thesis Defence

Title: “Movement behaviours and cardiovascular risk factors in individuals living with type 1 diabetes”

Supervisory Committee: Dr. Darren Warburton (Research Supervisor), Dr Veronica Jamnik, Dr Michael Koehle
University Examiners: Drs. Alex Scott, Mary Jung
External Examiner: Dr. Ronald Sigal
Chair: Dr. Linda Li

Abstract: Type 1 diabetes (T1D) is associated with an increased risk of cardiovascular disease (CVD) related morbidity and premature mortality. Research has shown that movement behaviours (physical activity, sedentary behaviour (SB), and sleep) are related to cardiovascular health; and especially, physical activity plays an important role in the prevention of CVD and the improvement of overall health and wellbeing in individuals that have T1D.

The purpose of this dissertation was to evaluate cardiovascular responses to long-term exercise training (Chapter 2), and acute high intensity interval (HIIE) versus moderate intensity continuous exercise (MICE) in individuals with T1D (Chapter 3); to assess movement behaviours and CVD risk factors in adolescents living with T1D, in comparison with their peers living without T1D (Chapter 4); to examine the individual relationships between movement behaviors and CVD risk factors (Chapter 4 & 5); to investigate the combined effect of time spent in physical activity, SB and sleep which together can be considered to constitute a composite whole on CVD risk factors within a compositional data analysis framework (Chapter 6). In Chapters 2 and 3, we conducted two systematic reviews and meta-analyses. In Chapters 4, 5 and 6, 48 adolescents living with T1D and 19 of their peers living without T1D were studied, movement behaviours and CVD risk factors were assessed.

We found that exercise training increased aerobic fitness and reduced glycated hemoglobin (HbA1c), daily insulin dosage and total cholesterol (Chapter 2) and HIIE may be safer than MICE for individuals with T1D, as it carries a lower risk of early-onset hypoglycemia without causing a higher occurrence of hyperglycemia and nocturnal hypoglycemia (Chapter 3). In Chapters 4, 5 and 6, we found that adolescents living with T1D presented early signs of CVD risk and demonstrated lower physical activity levels and aerobic fitness compared to their peers without T1D. Being physically active is associated with reduced risk factors for CVD in those individuals. Movement behaviours including regular physical activity, reducing sedentary behaviours, and obtaining adequate sleep play important roles in the prevention of CVD in adolescents living with T1D, optimizing these behaviours may lead to improvement of cardiovascular health in these individuals.