Associations of Moderate-to-Vigorous Physical Activity Timing with Type 2 Diabetes Incidence in UK Biobank and Glycemic measures in NHANES Running Title: MVPA timing and type 2 diabetes

<b>Objective: </b>We assessed whether timing of accelerometer-derived moderate-to-vigorous physical activity (MVPA) was associated with incident Type 2 Diabetes (T2D) and glycemic measures, independent of total daily MVPA. <br/><br/><b>Research design and methods: </b>Hourly accelerometer-derived MVPA from UK Biobank (UKB) and NHANES were used as exposure. The associations between MVPA timing with incident T2D in UKB (N=84,528, prospective), and prevalent diabetes and glycemic measures in NHANES (N=6,998, cross-sectional) were assessed using regression models adjusted for confounders and total daily MVPA. <br/><br/><b>Results:</b> In UKB, compared to those undertaking early morning (05:00–9:59) MVPA, T2D risk was lower in people undertaking MVPA in afternoon-evening (15:00–24:00) (HR=0.73 [95%CI 0.61–0.87]), late morning-midday (10:00–14:59) (HR=0.83 [95%CI 0.70-0.98]). In NHANES, afternoon and early evening MVPA were weakly associated with more favorable glycemic measures and lower diabetes prevalence. <br/><br/><b>Conclusions:</b> MVPA during the afternoon-evening was associated with fewer incident T2D, prevalent diabetes and more favorable glycemic measures. <br/>