Peripheral Polyneuropathy and Cognitive Impairment in Type II Diabetes Mellitus

BACKGROUND: Neuropathy is one of most common complications in diabetic patients. Diagnosis of diabetic neuropathy is essential for decreasing the rate of the disability and death. Neuron-specific enolase (NSE) is released from damaged neuronal cells and enters the blood circulation through an injured blood brain barrier. Therefore, serum NSE can reflect the damage of neurons and brain tissue. OBJECTIVE: To evaluate peripheral polyneuropathy and cognitive function in Type 2 Diabetes Mellitus (T2DM) and correlate them with NSE level as a possible biomarker of diabetic neuropathy. SUBJECTS AND METHODS: Forty five T2DM patients with polyneuropathy were randomly recruited in this study compared to 45 healthy age and sex matched subjects as a control. Patients group were divided into two subgroups, 24 diabetic patients with painful peripheral neuropathy and 21 with painless peripheral neuropathy. All were subjected to clinical assessment by diabetic neuropathy symptom score, Dyck neuropathy grading, Mini-Mental State Examination (MMSE), assessment of HbA1c, NSE biomarker and neurophysiological assessment (nerve conduction study (NCS), event related potential (P300wave) and somatosensory evoked potential (SSEP) of the right median nerve). RESULTS: There were significant decrease in cognitive functions in diabetic patients compared to controls and a significant increase in NSE in diabetic patients. There were no significant difference between patients with painless and painful diabetic neuropathy as regard MMSE, HbA1c and NSE. There were significant correlation of P300 in diabetic patients with HbA1c and NSE. CONCLUSION: Neurophysiological assessment of diabetic patients by NCS, SSEP and P300 have well evaluation of cognitive functions, painless, and painful diabetic polyneuropathy. NSE is a beneficial biomarker in diabetic patients to pick up neurological complications.