Diabetes is a chronic metabolic disorder affecting a large proportion of the global population. Diabetes is characterized by hyperglycemia resulting from insulin resistance, impaired insulin secretion, or a combination of both. This condition is associated with an increased risk of cardiovascular disease and microvascular complications.1,2 The importance of glycemic control in diabetes management is well known, and weight loss and fat loss are often advocated as management strategies for type 2 diabetes.3., 4., 5. On the other hand, it is also recognized that a loss of muscle mass, including sarcopenia, has a negative effect on insulin resistance and diabetes because skeletal muscle is a metabolic control organ with the greatest glucose disposal capacity in the body.6., 7., 8. The relationship between body composition and diabetes is complex. While changes in body composition affect the risk of developing diabetes,9., 10., 11. diabetes adversely affects skeletal muscle mass or glucose metabolism,12., 13., 14., 15. suggesting that changes in body composition play an important role in the development and progression of diabetes. However, the extent to which short-term changes in body composition affect fluctuations in HbA1c levels remains unclear.

Bioelectrical impedance analysis (BIA) is a non-invasive method that is widely used to assess body composition in various populations, including patients with diabetes,16,17 because changes in body composition, such as changes in muscle mass and fat mass, may affect glucose metabolism and insulin sensitivity.18,19 This study investigated the relationship between changes in glucose metabolism and body composition in patients with diabetes using BIA. We aimed to determine whether a change in HbA1c (ΔHbA1c), which is commonly used as an indicator of glycemic control, is associated with changes in body composition indices, such as fat mass, muscle mass, and bone mineral content.