Sedentary Behavior and Diabetes Risk Among Women Over the Age of 65 Years: The OPACH Study
Research Design and Methods: Women without physician-diagnosed diabetes (n=4839, age=79±7) wore accelerometers for ≥4 days and were followed up-to six years for self-reported newly-diagnosed diabetes requiring treatment with medications. Hazard ratios (HRs) for incident diabetes were estimated across quartiles (Q) of accelerometer-measured ST and mean bout duration using Cox proportional hazard models. Isotemporal substitution analyses using Cox regression tested associations with risk for diabetes after statistically replacing ST with light physical activity (PA) or moderate-to-vigorous PA (MVPA) and after replacing light PA with MVPA.
Results: During 20949 person-years, 342 diabetes cases were identified. Women in ST Q2, Q3, and Q4 (vs. Q1) had incident diabetes HR(95% confidence interval) of 1.20(0.87-1.65), 1.33(0.97-1.82), and 1.21(0.86-1.70); p-trend=0.04. Respective HR(95%CI) following additional adjustment for body mass index and MVPA were 1.04(0.74-1.47), 1.04(0.72-1.50), and 0.85(0.56-1.29); p-trend=0.90. Fully adjusted isotemporal substitution results indicated that each 30 minutes of ST replaced with MVPA (but not light PA) was associated with 15% lower risk for diabetes [HR=0.85(0.75-0.96); p=0.01]; the HR(95%CI) for replacing 30 minutes of light PA with MVPA was 0.85(0.73-0.98); p=0.03. Mean bout duration was not associated with incident diabetes.
Conclusions: Statistically replacing ST or light PA with MVPA was associated with lower diabetes risk in older women. While reducing ST is important for several health outcomes, results indicate that to reduce diabetes risk among older adults, the primary public health focus should be on increasing MVPA.