Time-of-day moderate-to-vigorous physical activity and all-cause mortality in individuals with type 2 diabetes.

There is no clear evidence for the best time of day for physical activity in benefitting health among individuals with type 2 diabetes. This study was aimed to examine whether there is an optimal time of day for physical activity to increase longevity. In this cohort study of 904 patients with type 2 diabetes, we fitted a Cox model with restricted cubic spline to examine the association of moderate-to-vigorous physical activity (MVPA) and time of day with all-cause mortality. Compositional data analysis was used to examine the association of time spent in sedentary behaviour (SB), light-intensity physical activity (LIPA), morning MVPA, and evening MVPA with all-cause mortality. MVPA was inversely associated with all-cause mortality in a curvilinear manner (P-value for nonlinearity<0.0001). The interaction between MVPA and time of day was not significant (P-value for interaction=0.11). Substituting evening MVPA with morning MVPA was not associated with appreciable changes in all-cause mortality. There is no evidence that the time of day moderates the association of MVPA with all-cause mortality. Patients with higher levels of MVPA had lower mortality regardless of the timing of MVPA. Patients with type 2 diabetes should engage in regular physical activity whenever possible.