[Early evaluation of auditory dysfunction in patients with type 2 diabetes mellitus]

We investigated auditory dysfunction in type 2 diabetic patients with normal hearing.

Forty patients (22 females; 18 males; mean age 55 years; range 32 to 76 years) with type 2 diabetes were examined by distortion product otoacoustic emissions (DPOAE) and auditory brainstem responses (ABR). The patients were evaluated with respect to disease duration, microangiopathy, peripheral neuropathy, and metabolic control. The results were compared with those of 22 healthy controls.

Compared to controls, diabetic subjects had decreased DPOAE amplitudes at all frequencies, being significant at 4 kHz (p=0.011); ABR recordings showed a significant difference only in the III-V interwave interval latency (p=0.042). In the diabetic group, poor metabolic control was associated with significantly decreased DPOAE amplitudes at 4 kHz (p=0.046) and 8 kHz (p=0.020); the presence of microangiopathy was associated with prolonged ABR I-V interwave latency (p=0.039); and neuropathy was associated with decreased DPOAE amplitudes at 0.75 kHz (p=0.022), 1 kHz (p=0.019), and 3 kHz (p=0.049), and ABR differences in the absolute latency of wave III (p=0.007) and the I-III interwave latency (p=0.023). The duration of disease did not affect auditory function (p>0.05).

Our results suggest that type 2 diabetes mellitus may lead to auditory dysfunction of cochlear and retrocochlear origin, and that microangiopathy, neuropathy, and poor metabolic control have adverse effects on auditory function.