Background: Since the ratio of creatinine to cystatin C (Cre/CysC) can re ect muscle volume, it has been proven to be a predictor of sarcopenia in patients with or without diabetes. Here, we investigated the predictive value of Cre/CysC in skeletal muscle composition and its correlations with glucose disposal ability and diabetic complications in patients with type 2 diabetes. Methods: The skeletal muscle index (SMI) and mean skeletal muscle attenuation (MMA) values of 193 patients with type 2 diabetes were obtained through analyses of CT images at the lumbar 3 level.Results: Serum Cre/CysC was signi cantly correlated with both the SMI (r =0.375, P < 0.001) and MMA (r = 0.378, P < 0.001). Multiple stepwise linear regression analysis demonstrated that Cre/CysC was the only biochemical predictor of the SMI [b = 0.48, (95% Cl, 0.02 to 0.94) and MMA [b= 0.57, (95% Cl, 0.14 to 1.01). In the diabetic complications analysis, Cre/CysC was negatively correlated with cardiovascular disease (r = -0.190, P = 0.008) and lower extremity arterial disease (r = -0.209, P = 0.004). Moreover, in the 100 g steamed bun test, Cre/CysC was signi cantly correlated with glucose levels at 60 min (r = -0.162, P = 0.045), 120 min (r = -0.287, P < 0.001) and 180 min (r = -0.313, P < 0.001).Conclusions: Cre/CysC is a valuable predictor of skeletal muscle composition in type 2 diabetes. Patients with higher levels of Cre/CysC may have a better ability to dispose of postprandial glucose and lower risk of macrovascular disease.