Involvement of the auditory organ in type 1 diabetes mellitus

The aim of this study was to evaluate auditory organ function in relatively young type 1 diabetic patients, with short duration of the disease and without overt hearing loss. The impact of age, diabetes duration and metabolic control on hearing function was also analysed.

Thirty-one patients with type 1 diabetes, aged below 45 years (mean 29.1 ± 7.1 years), with diabetes duration of less than 120 months (mean 54.7 ± 32.5 months), and no evident hearing impairment, were compared to 26 age-matched (30.3 ± 7.8 years, p = 0.567) healthy volunteers. In all subjects, pure-tone audiometry, transient evoked otoacoustic emissions (TEOAE), and auditory brainstem responses (ABR) were performed, after an ENT examination.

In diabetic patients, compared to healthy subjects, the mean hearing threshold in the pure-tone audiometry was significantly higher at high frequencies, the mean amplitude of TEOAE was lower (7.75 ± 4.43 dB v. 10.00 ± 4.01 dB, p < 0.001), and latency times of wave V and interval I-V in ABR were longer (5.78 ± 0.25 ms v. 5.69 ± 0.18 ms, p = 0.025 and 4.03 ± 0.20 ms v. 3.95 ± 0.17 ms, p = 0.017 respectively). In the diabetic group, the hearing threshold showed positive linear correlation with age, whereas TEOAE was inversely correlated with this parameter. In ABR latency, times of wave V and interval I-V were negatively correlated with diabetes duration.

This study confirms the involvement of the auditory organ in type 1 diabetes mellitus. To determine the prognostic and predictive values of this finding, and methods of possible prevention of hearing loss, further prospective observations are required.