Body mass index is associated with muscle strength, functional capacity, balance, and quality of life in patients with type 2 diabetes: A cross-sectional study

Background Type 2 diabetes mellitus (T2DM) is accompanied by obesity and elevated body mass index (BMI), which may be associated with poorer physical function and quality of life (QOL). However, associations of BMI with muscle strength, functional capacity, balance, and QOL have not been comprehensively evaluated together in T2DM.Purpose To evaluate associations of BMI with muscle strength, functional capacity, balance, and QOL in patients with T2DM.Methods Patient characteristics were recorded. Body composition, muscle strength, functional capacity, balance, and QOL were assessed using validated measures. Bivariate Pearson correlations were supplemented by partial correlations controlling for age, sex, height, diabetes duration, glycated hemoglobin A1c (HbA1c), and insulin use.Results Fifty patients with T2DM were included (age: 52.90 ± 9.27 years; BMI: 33.76 ± 7.18 kg/m2). In unadjusted analyses, higher BMI was associated with greater adiposity, lower skeletal muscle mass percentage and handgrip strength, shorter 6-minute walk test (6MWT) distance, lower Berg Balance Scale scores, and poorer QOL, but not with quadriceps strength, resting metabolic rate, Biodex balance parameters, or several QOL subdomains. After adjustment, BMI remained associated with body fat percentage (partial r = 0.854, p < .001), skeletal muscle mass percentage (partial r = -0.665, p < .001), 6MWT distance (partial r = -0.545, p < .001), and Nottingham Health Profile (NHP) pain (partial r = 0.426, p = .004), mobility (partial r = 0.440, p = .003), and total score (partial r = 0.351, p = .019). Associations with handgrip strength (p = .728) and Berg Balance test score were no longer significant (p = .069).Conclusion After adjustment for confounders, higher BMI remained associated with higher body fat percentage, lower skeletal muscle mass percentage, shorter 6MWT distance, and poorer QOL, whereas associations with handgrip strength and functional balance were attenuated. BMI-related functional findings should be interpreted cautiously in light of potential confounding.