Sex‐specific associations between skeletal muscle mass and incident diabetes: A population‐based cohort study

Abstract Aims To investigate the sex‐specific associations between predicted skeletal muscle mass index (pSMI) and incident type 2 diabetes in a retrospective longitudinal cohort of Chinese men and women. Materials and Methods We enrolled Chinese adults without diabetes at baseline from WATCH (West chinA adulT health CoHort), a large health check‐up‐based database. We calculated pSMI to estimate skeletal muscular mass, and measured blood glucose variables and assessed self‐reported history to identify new‐onset diabetes. The nonlinear association between pSMI and incident type 2 diabetes was modelled using the penalized spline method. The piecewise association was estimated using segmented linear splines in weighted Cox proportional hazards regression models. Results Of 47 885 adults (53.2% women) with a median age of 40 years, 1836 developed type 2 diabetes after a 5‐year median follow‐up. In women, higher pSMI was associated with a lower risk of incident type 2 diabetes ( P nonlinearity = 0.09, hazard ratio [HR] per standard deviation increment in pSMI: 0.79 [95% confidence interval {CI} 0.68, 0.91]). A nonlinear association of pSMI with incident type 2 diabetes was detected in men ( P nonlinearity < 0.001). In men with pSMI lower than 8.1, higher pSMI was associated with a lower risk of incident type 2 diabetes (HR 0.58 [95% CI 0.40, 0.84]), whereas pSMI was not significantly associated with incident diabetes in men with pSMI equal to or greater than 8.1 (HR 1.08 [95% CI 0.93, 1.25]). Conclusions In females, a larger muscular mass is associated with a lower risk of type 2 diabetes. For males, this association is significant only among those with diminished muscle mass.