BACKGROUND AND AIMS: Sarcopenia and diabetes are prevalent diseases among middle-aged and elderly population. This study aimed to investigate the bidirectional association between sarcopenia and diabetes. METHODS: This study comprised two longitudinal analyses. In cohort 1, the association between baseline diabetes and the risk of new-onset sarcopenia was assessed. In cohort 2, the association between baseline sarcopenia and the risk of new-onset diabetes was examined. Multivariate logistic regression models were used to calculate odds ratios (OR) and 95 % confidence intervals (95 % CI). Cross-lagged panel analysis was used to further validate their bidirectional associations. RESULTS: Significant bidirectional associations were observed between sarcopenia and diabetes in both cross-sectional and longitudinal analyses (P <
0.05). After four years of follow-up, low handgrip strength (OR: 2.31, 95 % CI: 1.74-3.08) and appendicular skeletal muscle mass index (ASM/Ht CONCLUSIONS: This study identified significant longitudinal bidirectional association between sarcopenia and diabetes, highlighting that each condition serves as a risk factor for the other. Clinically, early assessments of handgrip strength and ASM/Ht