Abstract： Objective To investigate the early diagnostic methods of diabetic nephropathies.Methods Turbidimetric immunoassay method were used to measure serum cystatin C (CysC),immunoglobulin G (IgG),urinary microalbumin (mAlb),alpha1 microglobulin (α1-MG) and beta2 microglobulin (β2-MG).Results There was a statistically significant difference in the levels of serum CysC,IgG and urinary α1-MG,β2-MG between patients without nephropathy group and the control group [serum Cysc:(1.48 ± 1.30) mg/L vs (0.76 ± 0.18) mg/L; serum IgG:(4.8 ±1.2) mg/L vs (3.9 ± 0.5) mg/L; urinary α1-MG:(15.0 ± 8.1) mg/L vs (2.2 ± 0.9) mg/L; urinary β2-MG:(5.9 ± 2.7) mg/L vs (1.8 ± 0.5) mg/L,all P ＜ 0.05].Serum CysC,IgG and urinary mAlb,α1-MG,β2-MG in cases of diabetic nephropathy were significantly higher than those in the control group [serum CysC:(5.79 ±1.54) mg/L vs (0.76 ± 0.18) mg/L; serum IgG:(8.8 ± 1.5) mg/L vs (3.9 ± 0.5) mg/L; urinary mAlb:(27.0 ±18.1) mg/L vs (1.8 ± 0.3) mg/L; urinary α1-MG:(27.7 ± 13.2) mg/L vs (2.2 ± 0.9) mg/L; urinary β2-MG:(19.7±7.5)mg/Lvs (1.8±0.5)mg/L,all P＜0.01].Conclusion Combined detection of blood CysC,IgG and urinary mAlb,α1-MG,β2-MG in the diagnosis of early renal damage in diabetes is sensitive and reliable.