[Otoacoustic emissions and auditory brain stem responses in insulin dependent diabetic patients].

UNLABELLED: The relationship between diabetes mellitus and hearing impairment has been studied for more than 100 years, and is still a matter of controversy. In our study hearing in diabetic patients was studied by tonal audiometry, brain stem auditory evoked responses and evoked otoacoustic emissions. The aim of this study was to evaluate the function of peripheral and central auditory pathway in subjects with insulin dependent diabetes mellitus (IDDM). Possible correlation between auditory function and microangiopathy (retinopathy or nephropathy) also have been investigated. Cochlear activity was evaluated by means of otoacoustic emissions. The functional changes in the brain stem were evaluated by ABR. OAEs and ABR were measured in 42 normally hearing IDDM patients aged between 21 and 42 years, and 33 aged- and sex-matched non-diabetic control subjects. IDDM patients were distributed into two groups, 17 patients without microangiopathy and 25 patients with microangiopathy.
RESULTS: Both of the groups (diabetic and control) had normal and undifferentiated results in tonal and impedance audiometry. The mean amplitudes of various DPOAEs were significantly reduced in the diabetic group compared with control subjects. No correlations were found between microangiopathy and DPOAE amplitudes reduced. ABR latencies were longer in diabetic patients when compared with those of control subjects. These findings indicate a central disturbance in the auditory pathway. Microvascular complications (retinopathy or nephropathy) were associated only with the prolongation wave I latency. In conclusion, the combined use of different procedures for monitoring the central and peripheral portions of the auditory pathway in diabetic patients showed the existence of the alterations in the cochlear micromechanics and in the retrocochlear auditory pathway.