ABSTRACT
Background: Diabetes mellitus (DM) is a global pandemic affecting almost every organ in the body. Peripheral nervous system involvement in diabetes is well known but there are not many studies on central nervous system involvement. Visual evoked potential (VEP) is a sensitive, non-invasive test to detect central demyelination of optic nerve. The objective was to compare the visual evoked potentials in type-2 DM patients with that of healthy controls and to find out if any correlation is there with the duration and glycaemic control of the disease and to compare incidence of peripheral and central neuropathy in DM patients.Methods: Author included 50 DM patients and 50 age and sex matched controls. Patients with previous stroke, demyelination, diabetic retinopathy and other ophthalmological disorders were excluded. VEP was recorded using pattern reversal stimulation with EMG RMS MARK II machine and p100 latency was measured.Results: P100 latencies (ms) was significantly prolonged in diabetics with mean±SD of (111.24±5.28 ms) as compared to controls (101.30±1.66 ms) with p value <0.003. Also, there was significant correlation between duration of DM and P100 latency prolongation, but no significant correlation was present when compared with glycaemic control.Conclusions: Central neuropathy is very common in DM. It is related to duration of DM and not HbA1c unlike PNP which is related to both. Central neuropathy occurs even prior to development of retinopathy or PNP. Hence, VEP is a non-invasive and sensitive screening tool for early neurological involvement in DM.