Abstract: Objective To assess the diagnostic value of urine albumin / creatinine ratio(ACR), urine α1-microglobulin (α1-MG), urine β2-microglobulin (β2-MG) and serum cystatin C (CysC) level in patients of type 2 diabetes mellitus(T2DM) with early renal injury. Methods Totally, 108 patients with T2DM admitted to and treated in our hospital were included from May 2019 to January 2020, and divided into simple T2DM group(n =68, UAER <30 mg / 24h) and diabetic nephropathy group(n = 40, 30 mg / 24 h≤UAER <300 mg / 24 h) according to urinary albumin excretion rate (UAER). Another 30 healthy volunteers undergoing physical examination in the corresponding period were recruited as controls. The levels of urinary ACR, α1-MG, β2-MG and serum CysC were maintained and statistically analyzed. Receiver-operating characteristic(ROC) curve was mapped for evaluating the sensitivity and specificity of urinary ACR, α1-MG, β2-MG and serum CysC level in predicting early renal injury of diabetics by the area under curve (AUC). Results Patients in simple T2DM group and diabetic nephropathy group had higher level of urinary ACR, α1-MG, β2-MG and serum CysC than those of healthy controls(all P<0. 05). The urinary ACR,α1-MG, β2-MG and serum CysC levels were significantly higher in diabetic nephropathy group than in simple T2DM group(all P<0. 05). The AUC was 0. 923, 0. 851, 0. 755 and 0. 702, respectively for urinary ACR, α1-MG, β2-MG and serum CysC, and the sensitivity and specificity were 84. 4% , 75. 0% , 71. 9% and 62. 5% ; and 96. 4% , 85. 5% , 81. 8% and 67. 3% , respectively, for the four indicators described above. Conclusion Urinary ACR, α1-MG, β2-MG and serum CysC levels are important roles in early
renal injury in patients of diabetes mellitus. Measurement of the four indicators can be conductive to early diagnosis of diabetic nephropathy as well as reliable evidence for clinical estimation of such condition.

Key words: Type 2 diabetes mellitus, Early renal injury, Urine albumin / creatinine ratio, Urinary α1-microglobulin, Urinary β2-microglobulin, Cystatin C