Self-Reported Sitting Time and Markers of Inflammation, Insulin Resistance, and Adiposity

BackgroundSedentary behavior is emerging as an independent risk factor for chronic disease; however, potential mechanisms underpinning these observations are not well understood.PurposeThis study aimed to investigate the association of self-reported weekday sitting time with biomarkers linked to chronic low-grade inflammation, insulin resistance, and adiposity.MethodsThis study reports data from individuals attending a diabetes screening program, United Kingdom, 2004–2007; analysis was conducted in 2010. Sitting time and physical activity were measured using the International Physical Activity Questionnaire; biochemical outcomes included fasting and 2-hour postchallenge glucose, fasting insulin, C-reactive protein (CRP), leptin, adiponectin, and interleukin-6 (IL-6).ResultsThis study included 505 (female=46%; South-Asian ethnicity=19%, aged 59±10 years, BMI=29.5±4.7) individuals with valid sitting data. Increased sitting time was positively associated with fasting insulin, leptin, leptin/adiponectin ratio, CRP, and IL-6 in women, but not men, after adjustment for age, ethnicity, social deprivation, and smoking and medication status; interaction analysis revealed that the gender-specific differences were significant. The associations for women remained significant after additional adjustment for total moderate- to vigorous-intensity physical activity; however all associations were attenuated when further adjusted for BMI. There was no association between sitting time and glycemic status.ConclusionsTotal self-reported weekday sitting time was associated with biomarkers linked to chronic low-grade inflammation and poor metabolic health in women, but not men, independent of physical activity.