Fat infiltration of muscle, diabetes, and clinical fracture risk in older adults

Context: Older adults with type 2 diabetes are at higher risk for fracture compared with nondiabetic adults after adjustment for their higher bone mineral density. Infiltration of muscle by fat predicts increased risk of hip fracture. Objective: We investigated whether fat infiltration of muscle, which is greater in diabetic adults, is associated with all clinical fracture and whether it accounts for the increased fracture risk in those with diabetes. Design, Setting, and Participants: Data were analyzed from the Health, Aging, and Body Composition Study, a cohort of community-dwelling adults aged 70-79 yr. Glucose metabolism status and x-ray attenuation of thigh muscle were determined at baseline for 2762 participants. Main Outcome Measures: During a mean 8.2 ± 2.3 yr follow-up, 331 participants reported at least one clinical fracture. Results: Fat infiltration of muscle was higher in those with diabetes or impaired glucose metabolism than in those with normal glucose metabolism (P < 0.001). Fat infiltration of muscle was independently associated with a 19% increased risk of incident clinical fracture (multivariate hazard ratio = 1.19;95%confidence interval = 1.04-1.36); this association did not differ across glucose metabolism groups (P for interaction = 0.65). As previously reported, diabetes was associated with a greater fracture risk compared with normal glucose metabolism (hazard ratio = 1.42; 95% confidence interval = 1.07-1.89) after adjustment forbonemineral density, but further adjustment for fat infiltration of muscle did not attenuate this association. Conclusions: Fat infiltration of muscle predicts clinical fracture in older adults. Although fat infiltration of muscle is higher among those with diabetes, it does not account for their increased fracture risk.