Aim: Sodium-glucose co-transporter 2 inhibitor (SGLT2i) therapy has been demonstrated to improve glycemic control and reduce body weight and fat mass in type 2 diabetes mellitus (T2DM). Here, our aim was to investigate the effects of SGLT2i dapagliflozin-treatment on body muscle mass and muscle fat content in patients with T2DM.

Methods: We prospectively recruited uncontrolled (hemoglobin A1c [HbA1c] ＞7%) Japanese T2DM patients who had a body mass index (BMI) ＜35 kg/m². Patients were treated with dapagliflozin (5 mg/day) or non-SGLT2i medicines for six months to improve HbA1c. We investigated changes in body composition using bioelectrical impedance analysis and changes in psoas muscle mass using abdominal computed tomography (CT).

Results: Subjects were 50 T2DM patients (72% male) with a mean age of 56.1 years, mean BMI of 27.1 kg/m² and mean HbA1c of 7.9%. HbA1c, body weight, and BMI were significantly decreased in both treatment groups, and the HbA1c decrease was not significantly different between groups. Dapagliflozin treatment significantly decreased body weight and total fat mass without affecting skeletal muscle mass. The absolute change in soft lean mass and skeletal muscle mass was not significantly different between groups. Dapagliflozin treatment did not significantly decrease psoas muscle index, and the absolute change in this index was not significantly different between groups. Dapagliflozin therapy also produced a significant increase in CT radiation attenuation in the third lumbar paraspinal muscles compared with non-SGLT2i therapy.

Conclusions: Treatment with dapagliflozin for six months significantly improved glycemic control and reduced body weight without reducing muscle mass in T2DM patients.