Total sitting time and the risk of incident diabetes in Danish adults (the DANHES cohort) over 5 years: a prospective study

AIMS: To test the hypothesis that total sitting time is associated with incident diabetes, after adjustment for physical activity and obesity. METHODS: 72 608 Danish adults from the DANHES cohort reported their total sitting time in 2007-2008 and were followed-up for 5 years, in relation to register-based incident diabetes mellitus. Cox regression analyses were used, and the effect-modifying influence of obesity and physical activity assessed. RESULTS: The age-sex adjusted HR for developing diabetes among those who sat 10+ h/day as compared to <6 h/day was 1.35 (95% CI 1.17 to 1.57). The relative risks were similar by gender, but were largely attenuated by adjustment for potential confounding factors including physical activity, and statistically non-significant for all categories of body mass index except the obese. CONCLUSIONS: The association between total sitting time and incident diabetes is substantially moderated by physical activity and obesity. Total sitting time remains a risk factor for diabetes only in inactive and obese populations.