Not all steps are equal: independent prospective associations of stepping volume and patterns with incident type 2 diabetes mellitus in the Maastricht study.

backgroundStepping has been associated with reduced risk for type 2 diabetes (T2D), but existing prospective studies focus largely on average stepping volume (steps per day or week) and ignore important differences in how stepping is accumulated. Here, we examined independent associations of stepping volume and within and between day variability, with incident T2D.

methodsParticipants (n = 4594, 40-75y) without preexisting T2D from The Maastricht Study wore an activPAL3 accelerometer (6-7 days). Prospective associations of stepping volume (steps/day) with incident T2D were assessed using Cox proportional hazards models with restricted cubic splines, adjusted for age, sex, BMI, education, smoking, CVD, sedentary time and diet. Four indices of between-day (i-iii below) and within-day (iv below) stepping pattern were modelled alongside total steps/day. These were: (i) proportion of steps accumulated on the 2 most active days (%Active-2days), (ii) between-day step count variability (BDV) and (iii) inter-daily step count stability (IS), (iv) within-day variability in stepping (WDV) (variability in steps/hour). Higher values in %Active-2days, BDV and WDV indicate greater variation in stepping between or within days. Higher IS values indicate greater uniformity in hourly stepping pattern between days.

resultsOver 30,336 person-years of follow-up (mean 6.6y), 178 incident cases of T2D were recorded. A non-linear (p = 0.04) 'L-shaped' association was observed between stepping volume and T2D risk, with steeper risk reduction earlier in the steps/day distribution. Relative to accumulating ≤ 5000 steps/day, adjusted hazard ratios (95% CI) were 0.57 (0.34, 0.96) for 5000-7500 steps/day, 0.60 (0.65-0.94) for 7501-10,000 steps/day, 0.48 (0.25, 0.89) for 10,001-12,500 steps/day and 0.68 (0.37, 1.24) for > 12,501 steps/day. Higher %Active-2days, BDV, and lower IS, (cumulatively describing a stepping pattern which is variable between days and within days), were linearly associated with T2D risk independent of stepping volume. HRs per SD increase were: %Active-2days 0.70 (0.65, 0.97), BDV 0.69 (0.54, 0.89) and IS 1.32 (1.08, 1.63).

conclusionsSubstantial reductions in T2D risk can be achieved by accumulating more steps during the day. Further, accumulating steps in a pattern possibly reflecting periodic larger doses of stepping may provide additional reductions in T2D risk. Future research regarding volume and optimum patterns of stepping could form the basis of the next generation of public health guidance and interventions to improve health through movement.