Are Otoacoustic Emissions Effective for Characterizing Subclinical Auditory Impairment in Normal Hearing Individuals with Type I Diabetes Mellitus?

This critical review evaluated eight studies examining otoacoustic emissions (OAEs) in normal hearing individuals with Type I diabetes mellitus (DM) to determine if they are effective for characterizing subclinical auditory impairment as a result of the disease. All were prospective, non-randomized clinical cohort studies. Results indicate that despite normal hearing thresholds, otoacoustic emission amplitude levels are lower in individuals with Type I DM. It is suggested that otoacoustic emissions testing can be effective for identifying impairment attributable to Type I DM in a discrete area along the auditory pathway. However, OAEs cannot solely be used to characterize the nature of the auditory impairment given the complexity of the auditory system. Additional studies involving larger sample sizes, varied selection procedures and criteria and in depth afferent and efferent auditory pathway evaluation to the level of the auditory cortex are recommended before one can characterize the nature of the auditory impairment as a result of Type I diabetes mellitus.