Hearing Loss in Middle-aged Subjects with Type 2 Diabetes Mellitus

BackgroundComplications of type 2 diabetes mellitus (T2DM) can result in hearing loss, which is characterized by high-frequency sensorineural hearing impairment and accelerated age-related decline of the right ear advantage. This investigation aimed to determine which auditory functions are affected in middle-aged subjects with T2DM and the change of the right ear advantage.MethodsWe assessed the auditory function of 50 diabetic and 50 healthy subjects using pure-tone audiometry, auditory brainstem response and otoacoustic emissions.ResultsDiabetic subjects showed elevated thresholds at 4000 Hz and 8000 Hz (p <0.01) and increased wave V and interwave I−V latencies (p <0.01) when compared to healthy subjects. Consistently, subjects with diabetes also had smaller distortion product otoacoustic emission amplitudes at 2.0, 3.0 and 4.0 kHz (p <0.01) and smaller transient otoacoustic emission amplitude in the right ear when compared to healthy controls (p <0.05). Meanwhile, the right ear transient otoacoustic emission amplitude of subjects with T2DM was smaller than the left ear at 4.0 kHz (p <0.05).ConclusionsOur data suggest that middle-aged subjects with T2DM have subclinical hearing loss, impaired auditory brainstem response and diminished otoacoustic emissions, and the peripheral right ear advantage is being lost in middle-aged subjects with T2DM.