Insulin Resistance and Muscle Strength in Older Persons

Background. The functional consequences of an age-related insulin resistance (IR) state on muscle functioning are unknown. Because insulin is needed for adequate muscle function, an age-related insulin-resistant state may also be a determining factor. We evaluated the relationship between IR and handgrip muscle strength in men and women from a large population-based study (n ¼ 968). Methods. The degree of IR was evaluated by the homeostasis model assessment (HOMA) and muscle strength was assessed using handgrip. Results. Simple sex-stratified correlations demonstrated that, in men, body mass index-adjusted handgrip strength correlated positively with physical activity (r ¼0.321; p , .001), muscle area (r ¼0.420; p , .001), muscle density (r ¼ 0.263; p ¼ .001), plasma albumin (r ¼ 0.156; p ¼ .001), insulin-like growth factor-1 (r ¼ 0.258; p , .001), calcium (r ¼ 0.140; p ¼.006), and testosterone (r ¼0.325; p , .001) concentrations, whereas a negative association was found for age (r ¼� 0.659; p , .001) and myoglobin plasma levels (r ¼� 0.164; p ¼ .001). In women, body mass index-adjusted handgrip strength correlated positively with physical activity (r ¼ 0.280; p , .001), muscle area (r ¼ 0.306; p , .001), muscle density (r ¼ 0.341; p ¼ .001), plasma albumin (r ¼ 0.140; p ¼ .001), and insulin-like growth factor-1 (r ¼ 0.300; p , .001), whereas a negative association was found for age (r ¼� 0.563; p , .001), myoglobin levels (r ¼� 0.164; p ¼ .001), and IR (r ¼� 0.130; p ¼ .04). Conclusions. Sex-stratified analyses adjusted for multiple confounders showed that the relationship between IR and handgrip strength was found significant in women, whereas it was negligible and not significant in men.