A major study by the National Institutes of Health (NIH) has confirmed the correlation between diabetes and hearing loss that several earlier minor studies have pointed towards. The new study found that hearing loss is about twice as prevalent among diabetics as in the general population.
The researchers discovered a high rate of hearing loss in those with diabetes after analyzing the results of hearing tests given to a nationally representative sample of adults in the United States. The test measured participants’ ability to hear low, middle and high frequency sounds in both ears. The link between diabetes and hearing loss was evident across all frequencies, with a stronger association in the high frequency range. Mild or greater hearing impairment of low- or mid-frequency sounds in the worse ear was about 21% in 399 adults with diabetes compared to about 9% in 4,741 adults without diabetes. For high frequency sounds, mild or greater hearing impairment in the worse ear was 54% in those with diabetes compared to 32% in those who did not have the disease.
Adults with pre-diabetes (whose blood glucose is higher than normal, but not high enough for a diabetes diagnosis) had a 30% higher rate of hearing loss compared to those with normal blood sugar tested after an overnight fast.
Researchers analyzed data from hearing testes administered over a five year period to participants in the National Health and Nutrition Examination Survey (NHANES) conducted by the National Center for Health Statistics, part of the Centers for Disease Control and Prevention (CDC). Half of the 11,405 survey participants aged 20 to 69 were randomly assigned to have their hearing tested and nearly 90% of them completed the hearing exam and the diabetes questionnaire. In addition, 2,259 of the participants who received hearing tests were randomly assigned to have their blood glucose tested after an overnight fast.
Hearing loss from diabetes may be the result of either changes to the circulatory system resulting in less blood flow to the peripheral blood vessels (which includes the tiny arteries in the inner ear), or changes in the nervous system – typically death to some nerve endings (which also includes the hair cells in the inner ear).
Earlier U.S. studies that examined diabetes and hearing loss found a weaker association or no association, but these studies were based on smaller samples of older adults and they were not nationally representative. This was the first nationally representative sample of working age adults (20 to 69 years old) and the study found an association between diabetes and hearing impairment evident as early as ages 30 to 40.
Hearing loss is a common problem caused by aging, disease, heredity and noise. About 36 million Americans suffer from some form of hearing loss. Diabetes is a group of diseases marked by high levels of blood glucose resulting from defects in insulin production, insulin action or both. Diabetes affects nearly 21 million people in the United States and is a major cause of heart disease and stroke and the most common cause of blindness and kidney failure. Pre-diabetes, which causes no symptoms, affects about 54 million Americans, many of whom will develop type two diabetes within the next 10 years.
If you suffer from diabetes it would be beneficial to have a baseline audiogram as early as possible and then have audiograms performed every year or two in order to keep tabs on your hearing.
* Information and statistics from the National Institutes of Health (NIH) and from the Better Hearing Institute.