The Physical Activity Health Paradox in Type 2 Diabetes.

Introduction: The physical activity health paradox refers to the contrasting associations of leisure-time physical activity and occupational physical activity with cardiovascular disease, but whether this applies to Type 2 diabetes risk is unknown. This study aimed to investigate the physical activity health paradox and age-specific Type 2 diabetes.

Methods: Working adults (N=5,866) in Denmark aged 30-60 years enrolled in the Inter99 cohort at baseline in 1999 were followed in a Diabetes Register. Incidence rates of Type 2 diabetes as a function of age, sex, and separate and combined levels of self-reported occupational physical activity and leisure-time physical activity were modeled using Poisson regression, adjusting for relevant covariates in separate analyses (2024).

Results: Moderate/vigorous leisure-time physical activity was associated with lower risk of Type 2 diabetes than light (rate ratio=0.63, 95% CI=0.46, 0.85). Strenuous occupational physical activity was associated with a slightly higher risk of Type 2 diabetes than moderate occupational physical activity, but the association diminished adjusted for covariates (rate ratio=1.12, 95% CI=0.79, 1.58). Sedentary leisure-time physical activity combined with any level of occupational physical activity was associated with higher risk of Type 2 diabetes than light leisure-time physical activity/moderate occupational physical activity combined (e.g., sedentary leisure-time physical activity and demanding occupational physical activity) (rate ratio=1.68, 95% CI=1.14, 2.48). Moderate/vigorous leisure-time physical activity combined with any level of occupational physical activity was associated with lower risk of Type 2 diabetes (e.g., moderate/vigorous leisure-time physical activity and moderate occupational physical activity) (rate ratio=0.6, 95% CI=0.39, 0.92).

Conclusions: Leisure-time physical activity lowered the risk of Type 2 diabetes regardless of the level of occupational physical activity, whereas no similar beneficial effects were found for occupational physical activity level. The differential effects of occupational physical activity and leisure-time physical activity on Type 2 diabetes suggest that the paradox may also exist in Type 2 diabetes.