Background: We examined the association of time-of-day bout-related moderate-to-vigorous physical activity (bMVPA) with changes in glycemic measures and use of antidiabetic medications in adults with type 2 diabetes.

Methods: Look AHEAD participants were randomly assigned to a lifestyle intervention or a control group, in which the most intensive intervention occurred in Year 1. Among 1755 participants (age, mean ± SD 60 ± 7 years; 57% women) with 7-day waist-worn accelerometry data at Year 1, we grouped them by the timing of bMVPA (≥3 METs in ≥min bouts) : ≥50% of bMVPA during the same time period (Morning, Midday, Afternoon, or Evening; N=191-258) , <50% of bMVPA in any time period (Mixed; N=379) , and ≤1 day with bMVPA per week (Inactive; N=485) . Analyses were adjusted for covariates including socio-demographic factors, randomization arm, and clinics; then further adjusted for weekly bMVPA volume and intensity.

Findings: Timing of bMVPA was associated with changes in HbA1c across Year 1 (P=0.01) , independent of weekly bMVPA volume and intensity. Participants in the afternoon group as compared to the inactive group had a greater HbA1c reduction (mean: -0.16%; 95%CI: -0.33% to 0%) . Among non-insulin users the odds of discontinuation vs. maintaining or initiating antidiabetic medications across Year 1 trended to differ between the bMVPA timing groups (P=0.09) , with the afternoon group having the highest odds of discontinuation (OR vs. inactive group: 1.86; 1.14 to 3.02) .

Interpretation: Timing of bMVPA may be linked with improvements in glycemic control in adults with type 2 diabetes. While regular physical activity remains to be the cornerstone for blood glucose management in diabetes, our findings suggested that exercise interventions aimed to increase glycemic control in patients with diabetes can be enhanced by engaging in physical activity at specific times of the day. Experimental protocols are needed to test the causality.


J.Qian: None. R.Middelbeek: Research Support; Novo Nordisk. Q.Xiao: None. M.P.Walkup: None. M.Coday: None. M.Erickson: None. J.L.Unick: None. J.M.Jakicic: Advisory Panel; Spark360, Wondr Health, WW International, Inc. K.Hu: None. F.A.Scheer: None.


National Institutes of Health (K99HL148500, DK57136, DK57149, DK56990, DK57177, DK57171, DK57151, DK57182, DK57131, DK57002, DK57078, DK57154, DK57178, DK57219, DK57008, DK57135, DK56992, R01HL140574, RF1AG059867, RF1AG064312)

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