The measurement of body mass index (BMI) cannot distinguish between skeletal muscle mass, which is a major site for insulin-stimulated glucose uptake, and fat mass, which contributes to insulin resistance.1,2 Skeletal muscles also play important roles in glucose metabolism through glucose consumption and storage.3,4 Several cross-sectional studies have shown that skeletal muscle mass is inversely associated with insulin resistance and prediabetes.5,6 However, glycated hemoglobin (HbA1c) changes were negatively associated with the lean mass index and appendage lean mass.7 The adipose tissue is intricately associated with insulin resistance; however, no markers for insulin resistance have been identified. Some studies have shown that type 2 diabetes mellitus (T2DM) is more closely related to body fat percentage than BMI.8,9 Body composition assessment has become important in the diagnosis and treatment of patients with T2DM.

Lipid ratios have been investigated as reliable markers of insulin resistance. Lipid ratios such as low-density lipoprotein cholesterol/high-density lipoprotein cholesterol (LDL/HDL), total cholesterol (TC)/HDL, and triglyceride–glucose index (TyG) are superior to individual lipid levels in predicting insulin resistance.10., 11., 12. The complex relationships between skeletal muscle and glycemic efficacy in diabetes, and body fat mass and lipid ratio associated with insulin resistance, have not been fully elucidated. Therefore, this study aimed to investigate the correlation between changes in skeletal muscle mass index (SMI), fat mass index (FMI), HbA1c, and lipid ratio after T2DM treatment.