Prolonged Sedentary Behavior and Cardiometabolic Risk in Older Women With and Without Type 2 Diabetes: The SitWise Study

Purpose: Type 2 diabetes (T2D) significantly increases cardiovascular disease (CVD) risk in women. Sedentary behavior (SB) may confer risks independent of physical activity. This study examined associations between SB accumulation patterns and cardiometabolic risk markers in older women with and without T2D. We hypothesized that prolonged sedentary bouts (≥60 minutes) would correlate with poorer risk profiles. Methods: We conducted a cross-sectional study of women aged 60–76 years of similar body mass index with ( n = 9) and without ( n = 11) uncomplicated T2D. Accelerometers assessed total SB and time in bouts ≥60 minutes. Risk markers included insulin sensitivity (Matsuda Index and glucose infusion rate [GIR]) and skeletal muscle microvascular function (near-infrared spectroscopy-derived oxygen saturation). Linear regression models adjusted for physical activity and T2D status. Results: Each 1-hour increase in sedentary bouts ≥60 minutes corresponded weakly, though not statistically significantly, with decreased GIR (95% confidence interval [CI] [−1.24, 0.07], p = 0.08). Other associations differed by diabetes status: in women with T2D, the Matsuda index increased by 1.65 per hour of prolonged SB (95% CI: [0.45, 2.85], p = 0.02). Conversely, muscle oxygen saturation during exercise showed a T2D-specific decline; for every additional hour in ≥60-minutes bouts, oxygen saturation was lower by −0.74% (95% CI: [−1.25, −0.23], p = 0.02). Conclusions: Prolonged SB was associated with lower insulin sensitivity regardless of diabetes status and with impaired muscle oxygenation during exercise in women with T2D. Future research should determine if targeting SB accumulation patterns can reduce CVD risk in older adults with T2D. Sedentary Behavior in Older Women With and Without Type 2 Diabetes (SitWise); NCT04262128; https://clinicaltrials.gov/study/NCT04262128 .