A correlation between diabetes and hearing loss has also been established; however, the exact rationale for this remains unknown. One theory suggests that high blood glucose levels associated with diabetes may lead to damage to the blood vessels and nerves of the inner ear, similarly to how diabetes can be damaging to many other parts of the human body.
Similarly, there is evidence to suggest a link between cardiovascular disease and hearing loss. The inner ear is highly-vascularized, containing many blood vessels. Therefore, it is especially sensitive to blood flow and any abnormalities in the cardiovascular system. A study published in the Laryngoscope in 2009 found that audiogram patterns strongly correlate with cerebrovascular and peripheral arterial disease. Specifically, low-frequency sensorineural hearing losses were found to be associated with these cardiovascular diseases.
Lastly, a relationship between untreated hearing loss and dementia has been observed. For many years, researchers have theorized that social isolation resulting from untreated hearing loss contributes to the development of dementia. A study by the Lancet Commissions completed in July of 2017 confirmed that untreated hearing loss is associated with an increased risk for dementia due to the effects of untreated hearing loss on the brain. They found that when hearing loss is left untreated, this leads to decreased stimulation of the auditory nerve, resulting in decreased stimulation of the auditory cortex of the brain and consequently an increased risk of dementia. Fortunately, the study determined that when hearing loss is treated with amplification, the individual’s risk for dementia is similar to those with normal hearing.