Skeletal Muscle Mass Loss and Physical Function in Young to Middle-Aged Adult Patients With Diabetes: Cross-Sectional Observational Study.

Background: Recently, it has been reported that older adults with type 2 diabetes mellitus (T2DM) have lower skeletal muscle mass than healthy individuals. Although skeletal muscle mass in older adults with diabetes is occasionally reported, similar reports on young to middle-aged adults are limited.

Objective: This study aims to assess the prevalence of skeletal muscle loss in young to middle-aged adults with diabetes, examine the relationship between skeletal muscle loss and physical function in these patients, and examine whether there are differences in these characteristics between men and women.

Methods: This cross-sectional, observational study included patients younger than 65 years with T2DM who were admitted to our hospital between 2014 and 2022 for educational admission for glycemic control and requested rehabilitation by the Department of Metabolic Medicine. The control group consisted of patients who received rehabilitation during their hospitalization at our hospital and did not have diabetes. The main parameters included skeletal muscle mass, muscle strength, physical function, and activities of daily living.

Results: The prevalence of skeletal muscle mass loss in this study was 18.2% (10/55) in men and 7.7% (4/52) in women. The skeletal muscle mass index (SMI) was 7.7 (SD 0.8) and 8.4 (SD 0.5) for men in the T2DM and control groups, respectively, and 7.0 (SD 0.9) and 6.8 (SD 0.7) for women in the T2DM and control groups, respectively. Therefore, compared with the nondiabetes group, a significant difference was observed in men but not in women (men: P<.001, women: P=.35). Nonetheless, the diabetes group exhibited significantly lower physical functions, such as a walking speed of 1.3 (SD 0.2) m/s and 1.2 (SD 0.43) m/s for men and women in the T2DM group and 1.6 (SD 0.2) m/s and 1.5 (SD 0.1) m/s for men and women in the control group, respectively (men: P<.001, women: P<.001). One-leg standing time was measured as 30.7 (SD 26.9) seconds and 29.4 (SD 25.5) seconds for men and women in the T2DM group, compared with 100.5 (SD 30.6) seconds and 82.5 (SD 39.8) seconds for men and women in the control group, respectively, with the T2DM group's times being significantly lower (men: P<.001, women: P<.001). Univariate logistic regression analysis showed that SMI was significantly associated with age, BMI, and peripheral neuropathy (all P≤.002). Multiple logistic regression analysis showed that BMI exhibited the strongest association (odds ratio 1.15, 95% CI 1.07-1.23; P<.001), and peripheral neuropathy was also significantly associated with SMI (P=.009).

Conclusions: Patients with diabetes, even those who are not older adults, face an elevated rate of skeletal muscle mass loss, muscle weakness, and a decline in physical function; moreover, they are susceptible to dynapenia and presarcopenia. Therefore, early intervention focusing on muscle evaluation and exercise is crucial.