Serum phosphorylated neurofilament-heavy chain protein as a biomarker for peripheral neuropathy in type 2 diabetic patients: a case–control study

Abstract Background Diabetic peripheral neuropathy (DPN) has emerged as one of the most potent predictors of decreased quality of life in type 2 diabetes (T2D) patients. Early detection is essential for avoiding or delaying DPN hazards. Early neural damage is typically misdiagnosed by nerve electrophysiological tests. Thus, there is an increased need for simple and specific biomarkers for nerve damage that reflect early DPN. Phosphorylated neurofilament-heavy chain protein (pNF-H) is the main structure of neural axons that is released from axons into the blood upon axonal injury, making it a biomarker of axonal damage. Aim To study the application of serum pNF-H level as a biomarker for DPN in patients with T2D. Patients and methods Ninety age, gender, and body mass index-matched participants were recruited. The study included 35 T2D patients with DPN (DPN group), 35 T2D patients without DPN (non-DPN group), and 20 nondiabetic healthy individuals (control group). DPN was assessed by Neurological Symptomology Score (NSS), modified Neuropathy Disability Score (NDS), neurothesiometer, and 10-g monofilament. Clinical data and laboratory parameters were collected. Serum pNF-H levels were measured via ELISA. Results pNF-H serum levels were significantly higher in both diabetic groups versus the control group ( p < 0.001) and in the DPN group than in those without neuropathy ( p < 0.001). HbA1c, NSS, and NDS were positively correlated with pNF-H in the DPN group ( p = 0.01, < 0.001, and < 0.001, respectively). Age, diabetes duration, BMI, low-density lipoprotein, fasting plasma glucose, NSS, and NDS were positively correlated with pNF-H in the non-DPN group ( p = 0.003, 0.024, 0.041, 0.013, 0.011, < 0.001, and < 0.001, respectively). pNF-H was independently correlated with DPN. The cutoff value of serum pNF-H above which diabetic subjects were likely to develop DPN was 33.45 ng/dl. Conclusion Serum pNF-H levels are significantly higher in diabetic subjects, specifically those with peripheral neuropathy. pNF-H could be a potential biomarker of DPN in patients with T2D.