Abstract: This review focuses on the research progress of creatinine to cystatin C ratio (CCR) in metabolic syndrome (MetS) and its common complications, aiming to systematically summarize the value of CCR as an indicator for assessing muscle mass and renal function in the early diagnosis, risk stratification, and disease management of MetS, while providing new insights for improving its diagnostic and therapeutic standards. The article highlights that insulin resistance, the core pathological mechanism of MetS, interacts with sarcopenia, forming a vicious cycle. Studies demonstrate that CCR comprehensively reflects muscle metabolism and renal function status, exhibiting unique predictive potential in key MetS components such as obesity, diabetes, and hypertension. Additionally, research on the association between CCR and complications like metabolic associated fatty liver disease (MAFLD) and coronary heart disease underscores its clinical significance as a dynamic monitoring marker. However, current studies face limitations including significant gender disparities and inconsistent results. Future large⁃scale epidemiological investigations and clinical research are required to further elucidate the role of CCR in prognosis evaluation and personalized intervention for MetS, thereby providing scientific evidence to reduce the burden of metabolic syndrome⁃related diseases.

Key words: metabolic syndrome, creatinine?to?cystatin C ratio, metabolic associated fatty liver disease, kidney disease, insulin resistance