Tinnitus is a common auditory disorder in which patients experience noise in the absence of an external source. It is a consequence of irreversible cochlear damage. This study examined the distortion product otoacoustic emissions and P300 components of event-related potentials.

This study included a control group of 25 normal-hearing adults not complaining of tinnitus and a study group that consisted of 45 normal-hearing adults complaining of tinnitus. Measures included patient history, basic audiological evaluation, the Arabic version of Tinnitus Handicap Inventory, distortion product otoacoustic emissions testing and P300 recording.

The study group showed significantly higher hearing thresholds at all frequencies as well as delayed latencies and reduced amplitude of P300. The Tinnitus Handicap Inventory showed mean scores of 35.2 ± 16.9, and the distortion product gram showed higher amplitudes in the control group.

Patients with tinnitus might have neural dysfunction at either peripheral or central levels of the auditory pathway.

Glucose metabolism has a significant impact on inner-ear physiology. Therefore, hearing may be affected in gestational diabetes.

A matched case–control study was performed to evaluate 27 patients with gestational diabetes and 31 non-diabetic pregnant women with similar demographic characteristics. A medical history was taken for each participant, and otological inspections and high-frequency audiometry tests were performed.

There were no significant differences in average pure tone air–bone hearing thresholds between the groups (p > 0.05). However, evaluation of high-frequency hearing thresholds indicated significantly increased auditory thresholds at 10 kHz and 12 kHz for right ears and at 8, 10, 12 and 14 kHz for left ears in the gestational diabetes group (p < 0.001).

An investigation into cochlear damage in gestational diabetic patients showed significant high-frequency hearing loss. Further studies are needed to validate these findings in different ethnic groups and geographical populations.