Replacing sedentary time with sleep and physical activity: associations with physical function and wellbeing in Type 2 diabetes

Aims: To examine the associations of substituting sedentary behaviour (SB) for sleep, light physical activity (LPA) or moderate-to-vigorous physical activity (MVPA) with physical function and wellbeing. Methods: Cross-sectional data from 808 adults with Type 2 Diabetes Mellitus, (T2DM) were included. 24-hour behaviours were ascertained through accelerometery. Isotemporal substitution was used to estimate the theoretical substitution of SB for other 24-hour behaviours on associations with physical function and wellbeing markers. Results: Reallocating 30 min of SB to sleep was beneficially associated with 1.0% (95% CI: 0.1–1.9) higher sit-to-stand-60 (STS60) and 1.2% (0.1–2.3) Duke Activity Status Index (DASI) scores, 3.6% (1.5–5.5) lower Patient Hospital Questionnaire-9 (PHQ9) and 1.9% lower (0.1–3.7) Diabetes Distress scores. Whilst substituting SB with MVPA was associated with 3.8% (2.2–5.4) higher STS60 and 3.9% (2.0–5.9) DASI scores, and 4.7% (0.3–9.0) lower PHQ9 score. Replacing SB with LPA was associated with 4.1% (1.0–7.1) lower PHQ9 score. Conclusion: In adults with T2DM, theoretically replacing SB with sleep and physical activity, particularly MVPA is beneficially associated with markers of physical function and wellbeing. For wellbeing, associations for sleep were comparable (depression), or greater (diabetes distress), than for MVPA.