Tumor necrosis factor-α is a novel biomarker for peripheral neuropathy in type II diabetes mellitus: a clinical and electrophysiological study

Abstract

Background Tumor necrosis factor-α (TNF-α) is an adipocytokine locally produced by Schwann cells and has a role in nerve regeneration and regulation of apoptosis. The role of TNF-α in the development of diabetic peripheral neuropathy (DPN) is controversial. Objective The objective of this study was to evaluate TNF-α serum level in a group of type II diabetes mellitus (DM) patients with and without neuropathy in comparison with healthy age-matched control group. Design This is a cross-sectional case–control study. Settings The study was conducted in outpatient clinics of the diabetes and physical medicine, rheumatology, and rehabilitation departments. Patients Ninety patients diagnosed with type II diabetes were included in the study. Main outcome measures All patients were assessed for clinical neuropathy using neuropathy symptom score and neuropathy disability score. All patients underwent nerve conduction studies of both upper and lower limbs. They were divided into two groups: group I with confirmed DPN (n=60) and group II with DM but no peripheral neuropathy (n=30). Serum TNF-α level was measured in all previous DM patients (90 patients) in addition to 48 healthy age-matched controls. Results A statistically significant difference was detected between serum TNF-α level in controls and diabetic patients. Similarly, a significant difference was detected between its level in non-DPN patients and confirmed DPN patients, being higher in the latter. A positive significant correlation has been detected between TNF-α level and patients’ age, as well as blood cholesterol level. A positive significant correlation has been found between TNF-α level and both neuropathy symptom score and neuropathy disability score. A significant negative correlation had been detected between TNF-α level and motor amplitudes of both tibial nerves. Conclusion Serum TNF-α level might be a potential biomarker for peripheral neuropathy in type II DM.