Early Diagnosis of Distal Peripheral Polyneuropathy Due to Glucose Metabolism Disorders via Intraepidermal Nerve Fiber Analysis

OBJECTIVE: Polyneuropathy is the most frequent complication of diabetes mellitus (DM), which is a common disorder worldwide. Early diagnosis of this complication is critical for treatment planning. Recently, intra-epidermal nerve fiber (IENF) analysis has been used for the early diagnosis of diabetic neuropathy and was reported to be superior to both conventional fascicular nerve biopsy and other diagnostic tests. The present study aimed to determine the effect of early glucose metabolism disorders on the peripheral nerves using IENF analysis. METHODS: : This prospective study compared IENF nerve fiber density in 10 patients with early-stage DM and 12 patients with impaired glucose tolerance (IGT) to that of healthy controls in order to investigate fiber loss in the asymptomatic stage. RESULTS: Mean age of the DM and IGT groups was 53.4 ± 10.9 years and 50.8 ± 10.6 years, respectively. Neither the IGT nor DM patients had paresthesia. Neurological examination results of the patients were all in the normal range. Mean fiber density was 6.4 ± 2.7 mm-1 in the DM group, 7.5 ± 3.2 mm-1 in the IGT group, and 13.7 ± 2.7 mm-1 in the control group (p< 0.0001). Paired analysis of the groups showed a significant difference between the 2 patient groups and the control group. There was a statistically significant difference in mean nerve fiber density between the DM and control groups (p< 0.0001, Mann-Whitney U test), and between the IGT and control groups (p< 0.0001, Mann-Whitney U test); however, there wasn’t a significant difference between the DM and IGT groups (p= 0.5, Mann-Whitney U test). CONCLUSION: The results show that IENF density in the IGT and DM groups decreased in the asymptomatic stage of DM. This means that polyneuropathy can begin in the prediabetic period in patients with glucose metabolism disorders. This critical information highlighs the importance of the early diagnosis and treatment of glucose metabolism disorders in preventing neurological complication