The time of day when people were most active was associated with selected adiposity markers in type 1 diabetes mellitus (T1DM), but similar findings were not observed in type 2 diabetes mellitus (T2DM). In a cross-sectional study published in Diabetes, Metabolic Syndrome and Obesity, peak activity timing showed significant relationships with body mass index (BMI) and waist circumference in T1DM, while no cardiometabolic associations remained significant in T2DM.

The study included adults with T1DM or T2DM who wore a wrist accelerometer for 7 days. The timing of the most active five hours each day (M5time) was analyzed as linear and circular variables. Activity volume during those five hours (M5value) was also derived. Multiple linear regression assessed associations with glycemic control, blood lipids, and body composition, with false discovery rate (FDR) correction used for multiple testing.

A total of 891 people with T1DM and 1,381 people with T2DM were analyzed. In T1DM, linear M5time was associated with waist circumference after full adjustment (B=-0.32, SE=0.15; FDR P=0.047). Circular M5time was also associated with BMI (P=0.004) and waist circumference (P=0.001), with amplitudes of 1.32 kg/m² and 4.28 cm, respectively. Corresponding phases were 12:51 h for BMI and 13:06 h for waist circumference. In T2DM, no significant associations were identified between M5time and cardiometabolic markers after FDR correction.

The analysis showed that activity timing had limited but measurable associations with adiposity markers in T1DM, whereas no comparable associations were seen in T2DM. Physical activity at any time of day remains appropriate.