Sitting time and risk of cardiovascular disease and diabetes: a systematic review and meta-analysis

Context: Whether physical activity attenuates the association of total daily sitting time with cardiovascular disease (CVD) and diabetes incidence is unclear. This systematic review and meta-analysis examined the association of total daily sitting time with CVD and diabetes with and without adjustment for physical activity. Evidence Acquisition: PubMed, Web of Science, BASE, MEDLINE, Academic Search Elite and ScienceDirect were searched for prospective studies published between 1st January 1989 and 15th February 2019 examining the association of total daily sitting time with CVD or diabetes outcomes. Data extraction and study quality assessments were conducted by two independent reviewers. Pooled Hazard Ratios (HRs) were calculated using a fixed-effects model. The quality assessment and meta-analytic procedures were completed in 2018. Evidence Synthesis: Nine studies with 448,285 40 participants were included. Higher total daily sitting time was associated with a significantly increased risk of CVD (HR 1.29; 95%CI 1.27-1.30, p=<0.001) and diabetes (HR 1.13; 95%CI 1.04-1.22, p=<0.001) incidence when physical activity was not adjusted for. The increased risk for diabetes was unaffected when adjusting for physical activity (HR 1.11; 95%CI 1.01-1.19, p=<0.001). For CVD, the increased risk was attenuated but remained significant (HR 1.14; 95%CI 1.04-1.23, p=<0.001). Conclusions: Higher levels of total daily sitting time are associated with an increased risk of CVD and diabetes, independent of physical activity. Reductions in total daily sitting may thus be recommended in public health guidelines.