Objective  To investigate the clinical value of multiparametric ultrasonography in assessing skeletal muscle morphological and elastic changes in patients with type 2 diabetes mellitus (T2DM), and to screen effective diagnostic indicators for diabetes complicated with sarcopenia.

Methods The study enrolled 130 patients with T2DM who were admitted to Xinjiang Uygur Autonomous Region People’s Hospital from May 2024 to December 2025. According to the 2019 diagnostic criteria of the Asian Working Group for Sarcopenia (AWGS), they were divided into the T2DM-only group (n = 94) and the T2DM with sarcopenia group (n = 36). Seventy-nine healthy individuals who underwent physical examination during the same period were enrolled as the control group. General data collection, biochemical indicator testing, appendicular skeletal muscle mass index (ASMI) measurement, and ultrasound parameter collection of the biceps brachii, rectus femoris, and gastrocnemius were completed in all three groups. Differences in clinical and ultrasound indicators among the three groups were compared, and receiver operating characteristic (ROC) curves were plotted to evaluate the diagnostic efficacy of ultrasound indicators.

Results There were statistically significant differences among the three groups in body mass index (BMI), fasting blood glucose (FBG), ASMI, 6-m gait speed, grip strength, and 3-m timed up-and-go test time (all P ＜ 0.05). Compared with the T2DM-only group, the T2DM with sarcopenia group had lower BMI, ASMI, 6-m gait speed, and grip strength, and statistically significant differences were observed in ultrasound-measured biceps brachii thickness, gastrocnemius thickness, gastrocnemius Young’s modulus, and gastrocnemius pennation angle in dorsiflexion and plantarflexion positions (all P ＜ 0.05). ROC curve analysis showed that gastrocnemius pennation angle in the plantarflexion position had the highest area under ROC curve (AUC) for diagnosing T2DM complicated with sarcopenia (0.845, 95%CI 0.766-0.924), followed by gastrocnemius pennation angle in the dorsiflexion position (0.762, 95%CI 0.666-0.858), gastrocnemius Young’s modulus (0.761, 95%CI 0.689-0.834), and biceps brachii thickness (0.733, 95%CI 0.642-0.824).

Conclusions Skeletal muscle morphological and functional abnormalities may occur at an early stage in patients with T2DM, and the impairment is more pronounced in those complicated with sarcopenia. Multiparametric ultrasonography can quantitatively assess skeletal muscle, among which gastrocnemius pennation angle in the plantarflexion position, gastrocnemius pennation angle in the dorsiflexion position, gastrocnemius Young’s modulus, and biceps brachii thickness have good diagnostic efficacy for T2DM complicated with sarcopenia.