Background: Glycine inhibits the formation of advanced glycation end products that may cause central and peripheral neuronal damage, affecting also the auditory nerve.
Aim: To evaluate the effect of glycine on auditory nerve conduction and hearing level among patients with type 2 diabetes mellitus and auditory neuropathy.
Material and methods: Twenty grams of oral glycine per day were administered during 6 months to 28 type 2 diabetic patients aged 58 ± 6 years, with auditory pathway neuropathy. Hearing tests and evoked otoacustic potentials were performed regularly. Fifteen diabetic patients aged 49 ± 8 years, without auditory nerve neuropathy did not receive glycine and were followed as a control group.
Results: Among patients receiving glycine, a significant improvement in left ear audiometry at 125, 250 and 500 Hz and right ear audiometry at 500 Hz, was observed. Waves I, III and V (p= 0.02) of evoked otoacustic potentials improved significantly in the left ear and wave I in the right ear. Among controls, waves V and III of evoked otoacoustic potentials had a significant impairment in the left ear.
Conclusions: There was an improvement in auditory evoked potentials in patients receiving glycine and an impairment in untreated control patients.