Abstract: Objective　To investigate the clinical application significance of urine alpha-L-fucosidase （AFU） for screening early renal injury of diabetes mellitus （DM）. Methods　The 178 type 2 DM patients were classified into DM without nephropathy group（79 cases），DM with nephropathy in early stage group（54 cases） and clinical DM with nephropathy group （45 cases）， according to the 24 h urine microalbumin（mAlb） excretion rate. A total of 178 type 2 DM patients and 320 healthy subjects were enrolled in this study. By the continuous monitoring method established by our laboratory，the urine AFU，urine mAlb，urine beta₂-microglobulin（β₂-MG） and N-acetyl-beta-D-glucosaminidase（NAG） contents were detected. The results between the 2 groups were analyzed comparatively. Results　The linearity of the AFU determination was up to 300 U/L.The within-run coefficients of variation（CV） of high and low AFU concentration samples were 1.69％ and 1.26％ respectively.The between-run CV of high and low AFU concentration samples were 4.51％ and 3.52％ respectively.There was no interference for urine AFU when vitamin C， bilirubin and hemoglobin were 50 mg/L，136.8 μmol /L and 1 g/L.Compared with the control group［（0.82±0.45）U/ g·Cr，（11.54±8.81）mg/ g·Cr，（0.11±0.07）mg/ g·Cr and （9.08±5.21）U/ g·Cr］，the urine AFU， mAlb，β₂-MG and NAG significantly increased ［（2.87±0.91）U/ g·Cr，（67.62±21.27） mg/ g·Cr， （0.48±0.32） mg/ g·Cr and （29.23±8.29） U/ g·Cr］ in DM group （P<0.01）. The urine AFU，mAlb，β₂-MG and NAG among the 3 groups of patients with DM were statistically significant （P<0.01）， and the urine AFU was positively correlated with NAG in patients with DM（r＝0.859，P<0.01）. In the DM without nephropathy group， the positive rate of urine AFU was 19.0%，with specificity 85.7%，sensitivity 91.8%，Youden index 0.77 and diagnostic efficiency 89.9％.The level of urine AFU after the treatment in the DM with nephropathy group （99 cases）［（2.7±1.26）U/ g·Cr］ was significantly lower than that before the treatment［（4.6±1.72）U/ g·Cr］（P<0.01）. Conclusions　The determination of urine AFU is a valuable indicator for screening early renal injury of DM.

Key words: Alpha-L-fucosidase, Urine analysis, Diabetes mellitus, Renal injury