Renal Tubular Damage Marker, Urinary N-acetyl-β-D-Glucosaminidase, as a Predictive Marker of Hepatic Fibrosis in Type 2 Diabetes Mellitus

BACKGROUND: Non-alcoholic steatohepatitis is closely associated with the progression of diabetic kidney disease (DKD) in type 2 diabetes mellitus (T2DM). We investigated whether urinary N-acetyl-β-D-glucosaminidase (u-NAG), an early renal tubular damage biomarker in DKD, could be related to the degree of hepatic fibrosis in patients with T2DM. METHODS: A total of 300 patients with T2DM were enrolled in this study. Hepatic steatosis and fibrosis were determined using transient elastography. The levels of urinary biomarkers, including u-NAG, albumin, protein, and creatinine, and glucometabolic parameters were measured. RESULTS: Based on the median value of the u-NAG to creatinine ratio (u-NCR), subjects were divided into low and high u-NCR groups. The high u-NCR group showed a significantly longer duration of diabetes, worsened hyperglycemia, and a more enhanced hepatic fibrosis index. A higher u-NCR was associated with a greater odds ratio for the risk of higher hepatic fibrosis stage (F2: odds ratio, 1.99; 95% confidence interval [CI], 1.04 to 3.82). Also, u-NCR was an independent predictive marker for more advanced hepatic fibrosis, even after adjusting for several confounding factors (β=1.58, P<0.01). CONCLUSION: The elevation of u-NAG was independently associated with a higher degree of hepatic fibrosis in patients with T2DM. Considering the common metabolic milieu of renal and hepatic fibrosis in T2DM, the potential use of u-NAG as an effective urinary biomarker reflecting hepatic fibrosis in T2DM needs to be validated in the future.