Clinical Utility of Gait Speed Indices for Identifying Sarcopenia in Older Adults with Type 2 Diabetes

Background/Objectives: This study aimed to compare the diagnostic performance of usual gait speed (UGS), maximal gait speed (MGS), and gait speed reserve (GSR) for identifying sarcopenia in older adults with type 2 diabetes (T2D), and to examine whether combining gait indices improves diagnostic performance. Methods: This cross-sectional study included 117 older adults with T2D hospitalized for glycemic control. UGS and MGS were measured in the central 10-m section of a 16-m course, which included 3-m acceleration and deceleration zones on either side. GSR was calculated as the difference between MGS and UGS. Sarcopenia was diagnosed according to the AWGS 2025 criteria. Multivariable logistic regression was used to examine the associations between each gait index and sarcopenia. Diagnostic performance was evaluated using receiver operating characteristic (ROC) curve analysis, and the usefulness of a combined criterion based on UGS and GSR was also assessed. Results: Sarcopenia was identified in 32 participants (27.4%). UGS, MGS, and GSR were each associated with sarcopenia independently of clinical factors. UGS showed the highest sensitivity (90.6%), suggesting its potential usefulness as a screening measure, whereas GSR showed the highest specificity (83.5%), suggesting its potential usefulness in reducing false positives when identifying sarcopenia. In the ROC analysis of the three gait-related indices, the area under the curve (AUC) for MGS was the highest (0.79), but it was not significantly different from the AUC for UGS. The combined criterion of UGS < 1.07 m/s and GSR < 0.21 m/s improved specificity and yielded a high positive likelihood ratio (PLR = 6.5). Conclusions: UGS, MGS, and GSR each exhibit distinct diagnostic characteristics for sarcopenia. UGS may be useful for screening, whereas GSR may help improve specificity. In particular, combining UGS and GSR may provide complementary diagnostic information for identifying sarcopenia in older adults with T2D.