Longitudinal association of type 2 diabetes and insulin therapy with muscle parameters in the KORA-Age study.

AIMS: The aim of the current study was to investigate the association of type 2 diabetes (T2D) and insulin treatment with changes in muscle mass, muscle strength, and physical performance in older adults. METHODS: In 731 participants of the population-based KORA-Age study aged 74.6 ± 6.2 years (T2D: n = 118; insulin treatment: n = 20), skeletal muscle index (SMI [kg/m2]), hand grip strength (GS [kg]), and a timed up and go test (TUG [s]) were performed at baseline and after a follow-up time of 3 years. The association of T2D and insulin therapy with changes in muscle parameters was analyzed using linear regression models. RESULTS: After adjustment for sex, age, BMI, physical activity, smoking, and multimorbidity, T2D was associated with the change in SMI during follow-up (ß - 0.1 (95% CI - 0.3 to - 0.02) kg/m2; p = 0.02), but not with a change in GS (ß - 0.9 (95% CI - 1.9 to 0.04) kg) or TUG (ß - 0.1 (95% CI - 0.7 to 0.5) s). Insulin therapy was positively associated with change in SMI (ß 0.6 (95% CI 0.3-0.9) kg/m2; p = 0.001), but not in GS (ß - 1.6 (95% CI - 4.1 to 0.8) kg) or TUG (ß 1.6 (95% CI - 0.2-3.4) s) in comparison with treatment with oral anti-diabetic medication alone. CONCLUSIONS: Participants with T2D showed an accelerated decline in muscle mass compared to non-diabetic participants. Insulin therapy was associated with preserved muscle mass, but not muscle function parameters, indicating a discrepancy between muscle mass and function in this high-risk population.