Clinical significance of combined testing of serum cystatin C and urinary α_1-microglobulin in the diagnosis of early diabetic nephropathy

Objective The aim of the study was to investigate the diagnostic value of serum cystatin C(CysC) and urinary α1-microglobulin(α1-MG) in the early diabetic nephropathy.Methods The 524 type 2 diabetics in this study were divided into three different groups(mAlb normal group 0-30 mg/L,mAlb 31-100 mg/L和mAlb100 mg/L) according to their Urinary microglobulin(mAlb) value.Serum CysC,urinary α1-MG,BUN and Cr were measured in all individuals.Results By contrast to healthy control,the concentration of blood urea nitrogen(BUN) and creatinine(Cr) had not significantly increased in mAlb normal group(0-30 mg/L)(P0.05).However,the levels of serum CysC and urinary α1-MG significantly increased in three different groups of diabetics compared with healthy control(P0.05),and in a mAlb concentration dependent manner.The positive rates of serum CysC and urinary α1-MG were higher than those of BUN and Cr in three different groups of diabetics(P0.05).Combined measure of serum CysC and urinary α1-MG remarkably increased the positive rate in mAlb normal group(0-30 mg/L),and the result was better than serum CysC or urinary α1-MG alone(P0.05).The positive rate sequence of 4 testing items in diabetics groups with early impairment of renal function(mAlb 0-30 mg/L and mAlb 31-100 mg/L) was serum CysC + urinary α1-MG urinary α1-MG serum CysC BUNCr.Conclusion Serum CysC and urinary α1-MG are more efficacious than serum BUN and Cr in early diagnosis of diabetic nephropathy,and combined test of serum CysC and urinary α1-MG can significantly increase the positive rate of early renal impairment in diabetic patients.