Do Physical Activity and Sedentary Behaviours During Adolescence Predict the Development of Type 2 Diabetes During Early Adulthood?
Background: Little is known about whether adolescent physical activity and sedentary behaviour levels predict health in adulthood. The first objective of this thesis was to determine whether participation in moderate-to-vigorous physical activity in adolescence is associated with type 2 diabetes risk in adulthood. The second objective was to determine whether time spent in different types of sedentary behaviour (e.g., TV watching, reading) are associated with type 2 diabetes risk in adulthood. Methods: Data for the physical activity and sedentary behaviour analyses were based on 4845 and 3942 adolescents, respectively, who were aged 16 years at baseline. Physical activity was measured at baseline using a self-reported activity checklist where participants indicated what activities they participated in and how often they participated in them. Sedentary behaviour was assessed at baseline using a questionnaire where participants reported how much time they watched TV and videos, used the computer, read and did homework. Participants were followed for 30 years (from age 16 to age 46). Cases of type 2 diabetes were determined every 4 years in the follow-up period in a self-reported manner. Results: By comparison to those in the lowest physical activity quartile, those in quartile 2 had a 43% decreased risk of type 2 diabetes. However, type 2 diabetes risk was not significantly reduced in physical activity quartiles 3 and 4. By comparison to those who watched ≤120 minutes/day of TV and videos, those who watched >240 minutes/day had a 106% increased risk of type 2 diabetes. Time spent using the computer, reading and doing homework were not associated with type 2 diabetes risk. Conclusion: It appears that watching TV and videos, but not physical activity levels or other sedentary behaviours, is associated with type 2 diabetes risk.