Abstract: Objective: To explore the clinical value of single or combined detection of CysC, β2-MG and RBP in the early diagnosis of diabetic nephropathy.Method: A total of 106 patients with diabetic nephropathy diagnosed in endocrinology from Union Hospital of Tongji Medical College of Huazhong University of Science and Technology were collected from 2017.11 to 2018.10.According to the degree of nephropathy, 40 patients were divided into clinical diabetic nephropathy group.66 patients were divided into early diabetic nephropathy group, and 60 patients with diabetes mellitus without renal injury were selected as the disease control group.At the same time, 40 healthy volunteers were selected as the normal control group.The levels of serum CysC, β2-MG, RBP and clinical routine renal function indicators were detected in each group, and their relationship with early diabetic nephropathy was analyzed.Result: The levels of CysC, β2-MG and RBP in clinical diabetic nephropathy group were significantly higher than those in simple diabetic group, the early diabetic nephropathy group and the normal control group(P<0.05).The early diabetic nephropathy group was significantly higher than that of simple diabetic group(P<0.05), but there was no significant difference between the simple diabetic group and the control group(P>0.05).The positive rate of CysC was highest when the three indicators were used alone.The two combined tests were the highest with CysC and β2-MG.The positive rate of the combined detection of the three indicators was as high as 95%.The ROC curve evaluated the use of CysC, β2-MG and RBP alone or in combination to diagnose diabetic nephropathy.The results show that the area under the curve(AUC) of CysC, β2-MG, and RBP were 0.777, 0.863 and 0.901, respectively, when they were used alone.The area under the RBP curve was the largest.When CysC, β2-MG and RBP were used in combination, β2-MG combined with RBP AUC was 0.915, β2-MG combined with CysC AUC were 0.864, and RBP combined with CysC AUC was 0.899.β2-MG combined with RBP AUC was the largest.When CysC, β2-MG and RBP were used together, the AUC was 0.912.Conclusion: The combined detection of CysC, β2-MG and RBP in diabetic patients can improve the sensitivity and accuracy of diagnosis of renal damage in clinical diabetic patients.In addition, the level of renal function damage in diabetic patients can be judged by the level of the three indicators, which is helpful for the treatment and monitoring of diabetic nephropathy.