The aim of this study is to investigate the role of diabetes mellitus on the clinical and electrophysiological findings of peripheral facial palsy (PFP), the effect of the diabetes duration and polyneuropathy on the electrophysiological parameters. A total of 32 diabetic and 40 non-diabetic patients with peripheral facial palsy were included. All patients were divided into two subgroups based on the time of electrophysiological examinations: within the first 15 days versus within 16-30 days. Neuropathy symptoms and the results of neurological examinations and electrophysiological findings were recorded. The findings of electroneurography (EnoG), blink reflex (BR) evaluation, and needle electromyography (EMG) indicated statistically significant blink reflex abnormalities in diabetic patients compared to non-diabetics. Delay in the latency was more remarkable in the R2 component than in the R1 (p<0.001). The delay in the R1 latency was also observed in the non-affected side for diabetic patients. The longer duration of the diabetes caused significant delay on the blink reflex latency on both the affected and non-affected sides for RI component (p = 0.019, p=0.041, respectively). In contrary, neither the diabetes duration nor the age of the patients correlated with the clinical severity of facial palsy, fiber loss, fibular nerve compound muscle action potential amplitudes, and the nerve conduction velocities. (C) 2007 Elsevier Ireland Ltd. All rights reserved.