A diabetes diagnosis may leave you worrying about several things, but hearing loss? That may sound surprising, but studies have shown a connection.
Prevalence of Hearing Loss in Diabetics
Researchers analyzing data from a national health survey found that 21% of the diabetics surveyed had hearing loss, compared to only 9% of non-diabetics. Analyzing the data further, they found that people with hearing loss were also more likely to report that they have diabetes, too. This was true regardless of age, except for people 60 to 69 years old. Based on this data, the researchers estimated that there was a 28% prevalence of at least mild hearing loss in people with diabetes. Interestingly, the researchers found there was a stronger relationship between diabetes and high-frequency hearing loss than there was between diabetes and low or mid-frequency hearing loss.
In a separate study, researchers looked at older Australian people with diabetes. That study was concerned with age-related hearing loss. Half of the people with diabetes in the study had age-related hearing loss, while only 38% of those who were not diabetic had the same concern.
Physical Changes Wrought by Diabetes
Diabetes can cause multiple changes to the hearing mechanism.
People with diabetes often have less keratin -- a protein that lines the ear canal. When present in reduced amounts, hearing loss can occur.
In addition, the eighth cranial nerve -- one branch of which carries sound signals from the cochlea to the brainstem -- can also experience a deterioration of the sheath that protects its nerve fibers (demyelination). The tissue in the ear canal can also degenerate, affecting hearing.
The cochlea itself can experience a thickening of its walls or the loss of hair cells. Diabetes can even damage the nerves associated with hearing; higher blood sugar levels produce chemical changes that impact the nerves' ability to carry sound signals. The capillaries of the inner ear can also be thickened, causing similar results.
What Should People Diagnosed with Diabetes Do?
Due to the abundance of evidence linking hearing loss to diabetes, diabetics should get their hearing tested regularly in addition to monitoring their blood sugar. This is important because some experts say that the prevalence of hearing loss in diabetics may actually be higher than known.
Sources:
Kathleen E. Bainbridge, PhD, MPH; Howard J. Hoffman, MA; and Catherine C. Cowie, PhD, MPH. "Diabetes and Hearing Impairment in the United States: Audiometric Evidence from the National Health and Nutrition Examination Survey, 1999 to 2004." Annals of Internal Medicine. Volume 149, Number 1, July 2008.
P. Mitchell, B. Gopinath, C.M. Mcmahon, E. Rochtchina, J.J. Wang, S. C. Boyages, S. R. Leeder. "Relationship of Type 2 diabetes to the prevalence, incidence and progression of age-related hearing loss." Diabetic Medicine. Volume 26, Number 5, May 2009.
Learn more about diabetes. Check out the About.com: Type 2 Diabetes site.
