Evaluation of skeletal muscle mass indices, assessed by bioelectrical impedance, as indicators of insulin resistance in patients with type 2 diabetes

[Purpose] This study aimed to investigate the association between two skeletal muscle mass indices and insulin resistance, and to determine the skeletal muscle mass index that is beneficial in evaluating insulin resistance in patients with type 2 diabetes mellitus. [Participants and Methods] This study evaluated 136 male and 100 female patients with type 2 diabetes mellitus. The skeletal muscle mass was evaluated by bioelectrical impedance analysis. Two skeletal muscle mass indices were investigated as the appendicular skeletal muscle mass index (appendicular skeletal muscle mass divided by the square of height) and relative total skeletal muscle mass (total skeletal muscle mass as a percent of body weight). The homeostasis model assessment of insulin resistance was used as a marker of insulin resistance. Associations were investigated by grouping the participants according to gender and age (<60 or ≥60 years). [Results] The appendicular skeletal muscle mass index was positively associated with the homeostasis model assessment of insulin resistance, except in male patients aged ≥60 years, whereas the relative total skeletal muscle mass was significantly inversely associated with the homeostasis model assessment of insulin resistance, in all patient groups. The cutoff values of the relative total skeletal muscle mass for the presence of insulin resistance were 37.9% and 32.5% in male and female patients, respectively. [Conclusion] This finding suggests that relative total skeletal muscle mass may be a better indicator of insulin resistance than appendicular skeletal muscle mass index is, in patients with type 2 diabetes mellitus.