Association Between Early Markers of Renal Injury and Type 2 Diabetic Peripheral Neuropathy

OBJECTIVE: Diabetic kidney disease (DKD) and diabetic peripheral neuropathy (DPN) are both common chronic complications of type 2 diabetes mellitus (T2DM). The aim of this study was to examine whether some markers of early renal injury were associated with DPN. METHODS: Retrospective hospitalization data from 471 patients with T2DM were analyzed. Subjects were divided into DPN group and non-DPN group according to clinical history, symptoms, signs and nerve conduction study. Markers of glomerular injury [urinary albumin/creatinine ratio (UACR) and estimated glomerular filtration rate (eGFR)] and tubular injury [urinary N-acetyl-β-D-glucosaminidase/creatinine ratio (NAG/Cr) and urinary β2 microglobulin (β2-MG)] were innovatively combined to assess the association with DPN. Staging of chronic kidney disease (CKD) was classified as G1, G2, G3a, G3b, G4 based on eGFR categories of ≥90, 60–89, 45–59, 30–44, 15–29 mL/min/1.73m(2). RESULTS: DPN was detected in 71.1% of our population. Subjects in DPN group suffered from older age, longer duration of diabetes and worse blood glucose control compared with non-DPN group. The levels of UACR, NAG/Cr and β2-MG were significantly increased in DPN group than those in non-DPN group, while eGFR was decreased. The prevalence of DPN increased gradually in G1, G2 and G3–4 of CKD, which were 66.3%, 73.2% and 82.7% (P = 0.014). After adjusting for confounding factors, NAG/Cr >1.41 U/mmol (the highest tertile) was a consistently independent risk factor for DPN [odds ratio, OR (95% confidence interval, CI) = 1.86 (1.04–3.33)]. However, UACR, eGFR and β2-MG did not significantly affect the risk of DPN. CONCLUSION: When T2DM patients suffer from CKD, DPN will be more likely to appear, accelerate or deteriorate. Some easily available urinary markers of glomerular and tubular damage can be used for early prediction of DPN, in which increased NAG/Cr is an independent risk factor for DPN.