Cognitive Function Mediates the Association Between Type 2 Diabetes and Physical Performance Decline in Older Adults: A Cross-Sectional Study

Background: Elderly patients with type 2 diabetes mellitus (T2DM) often experience cognitive decline and physical function degradation. However, whether cognitive function mediates the association between T2DM and physical performance in older adults has not been previously examined. This study aimed to explore whether cognitive function was statistically associated with the relationship between T2DM and physical performance in older adults using mediation analysis. Methods: We conducted a cross-sectional study, and a total of 102 participants aged ≥60 were included (46 patients with T2DM and 56 non-diabetes controls). Cognition was assessed using standardized neuropsychological tests (global cognition, as assessed by the MoCA total score; and domain-specific measures). Physical performance was quantified by walking speed and handgrip strength. Mediation analyses were performed to test whether the cognitive function statistically accounted for part of the association between the T2DM state and the physical performance. Results: Participants with T2DM had poorer cognitive performance and lower physical performance than controls. In mediation models, the MoCA total score statistically accounted for approximately 18% of the association between T2DM and gait speed (ACME −5.19 cm/s, 95% CI −8.73 to −2.32; proportion mediated 0.18, 95% CI 0.08–0.32). For grip strength, the corresponding proportion was estimated at 60% (ACME −2.16 kg, 95% CI −3.78 to −0.81; proportion mediated 0.60, 95% CI 0.23–1.81), although this estimate should be interpreted cautiously because of the wide confidence interval. Conclusions: This study suggests that poorer cognitive performance may partially account for the observed relationship between T2DM and the decline in physical performance of the elderly. The results support the presence of concurrent cognitive and physical impairment among older adults with T2DM. Given the cross-sectional design, these findings should be regarded as exploratory and hypothesis-generating, and longitudinal studies are required to establish temporal relationships.