We determined the longitudinal association of time-of-day of bout-related moderate-to-vigorous physical activity (bMVPA) with changes in glycemic control across 4 years in adults with type 2 diabetes in the Look AHEAD trial.
Among 2416 participants (57% female; mean age, 59 years) with 7-day waist-worn accelerometry recording at year 1 or 4, we defined the time-varying exposure by time-of-day of bMVPA: ≥50% of bMVPA during the same time period (Morning, Midday, Afternoon, or Evening), <50% of bMVPA in any time period (Mixed), and ≤1 day with bMVPA per week (Inactive, the reference).
HbA1c reduction at year 1 varied by bMVPA timing (P=0.02), independent of bMVPA volume and intensity. The afternoon group had the greatest HbA1c reduction, the magnitude of which was 30%-50% larger than the other groups. The odds of discontinuation versus maintaining/initiating glucose-lowering medications at year 1 differed by bMVPA timing (P=0.04). The afternoon group had the highest odds (OR: 2.13 [1.29, 3.52]). For all the bMVPA timing groups, there were no significant changes in HbA1c between year 1 and 4.
bMVPA performed in the afternoon is associated with improvements in glycemic control in adults with diabetes, especially within the initial 12 months of an intervention.