Investigation of Auditory Processing Deficits in Patients with Diabetes Mellitus

The incidence of Diabetes Mellitus (DM) is about 9.6% in the US, and its prevalence is increasing rapidly and globally (NIDDKD, 2007). A common, but under-recognized, complication of DM is hearing difficulties. Although epidemiological studies (Bainbridge, et al., 2008) suggests that individuals with diabetes are twice as likely to have hearing loss as non-diabetic individuals, research on DM-related auditory deficits is relatively sparse and have been inconclusive and/or ambiguous regarding the nature of the hearing loss. We tested the hypothesis that the DM-related listening difficulties are manifestations of subclinical deficit(s) in higher-order auditory processing. Following a routine audiological evaluation, we examined a group of adult DM (Type II) patients with tests that assessed peripheral (high-frequencyaudiometry) and central processing (spatial listening, listening in competing noise, temporal processing and contralateral-suppression of OAEs) abilities. Our results indicate elevated high frequency pure-tone (>4 kHz) thresholds, increased difficulty listening in competing noise, poorer spatial listening skills, and poorer temporal processing abilities in the group of DM patients when compared to controls. These results suggest that central auditory processing deficits in patients with DM are more striking than commonly investigated peripheral deficits and thus contribute, and probably exacerbate, the functional listening difficulties experienced by these patients.