Do you frequently ask people to repeat themselves? Do you have trouble hearing in noisy restaurants? Do you think that others are mumbling?
All of these may be signs of hearing impairment, a widespread complaint that is twice as common in people with diabetes as it is with those who don’t have the disease.
According to the American Diabetes Association, about 30 million people in the US have diabetes, and an estimated 34.5 million have some type of hearing loss, with an apparent overlap between the two.
In 2008, a National Health and Nutrition Examination Survey (NHANES) looked at the association between diabetes and hearing impairment and found that twice the number of people with diabetes had hearing impairment than those without.
And among the 84 million adults who have prediabetes, the rate of hearing loss is 30% higher than those with normal blood glucose.
While it may appear that there is a connection between diabetes and hearing impairment, it isn’t yet understood how and why it occurs.
“Diabetes may cause hearing loss, which is likely a microvascular (or small blood vessel) disease similar to kidney and eye damage that can occur with diabetes,” said Kanif Munir, MD, associate professor of medicine at the Division of Endocrinology, Diabetes and Nutrition at the University School of Medicine in New York City. “The small blood vessels in the ear may be affected leading to a loss of hearing.”
“It is not completely clear if improving glucose control will help diabetes-related hearing loss, but if the mechanisms are similar to other microvascular disease, it may be helpful,” said Dr. Munir.
He also noted that type 2 diabetes and hearing loss are also age-related conditions “and there may be some overlap in age-related hearing loss and diabetes.”
“Some but not all studies have shown an increased risk of hearing impairment with increasing levels of blood glucose,” said Catherine Cowie, PhD, MPH, director of diabetes epidemiology programs for the NIH’s National Institute of Diabetes and Digestive and Kidney Diseases. Dr. Cowie noted that less is known about the association of type 1 diabetes with hearing impairment.
Hearing loss can happen gradually, with symptoms of impairment often hard to notice. Among the signs are:
A study published in 2011 in Diabetes Care examined risk factors for hearing loss in people with diabetes. It found that low HDL cholesterol (the “good” cholesterol that helps remove the “bad,” LDL cholesterol, from the arteries); coronary artery disease, peripheral neuropathy (nerve damage) and poor health in general increased the risk of hearing loss.
Among the general population, factors others than diabetes related to hearing impairment include being older, white, male, having a lower income, exposure to noise, family history, systemic diseases such as cardiovascular disease and stroke (as well as diabetes), obesity, ear infections and use of medications toxic to the ear.
“In people with diabetes, complications of diabetes may involve changes to nerves in the ear,” said Dr. Cowie. “These changes may include the capillaries and sensory neurons of the inner ear, but more research is needed to confirm it.”
In some cases, certain rare genetic syndromes may result in both hearing impairment and diabetes, said Dr. Cowie.
“In addition, some known causes of hearing loss, such as heart and nerve diseases, are also complications from diabetes,” said Dr. Cowie. “One theory for this hearing loss is that diabetes causes accelerated aging.”
While not all studies have shown a higher risk of hearing impairment with prediabetes, some have, including NHANES study, which showed an approximate 30% higher odds of having some loss.
“Prediabetes is associated with higher rates of hearing loss, and to prevent further complications should be managed with diet, exercise, and possibly pharmacologic agents if appropriate,” said Dr. Munir.
“Prediabetes is also associated with an increased risk of certain diabetes complications such as cardiovascular disease and microvascular disease,” said Dr. Cowie. “Hearing impairment in part depends on the conditions the individual with prediabetes may have, such as hypertension and hyperlipidemia (an abnormally high concentration of fats or lipids in the blood).”
While most hearing impairment cannot be reversed, prevention of the progression of hearing loss “may be possible by making lifestyle changes such as increased physical activity, maintaining a healthy diet, and trying to control blood glucose and blood pressure and blood lipids,” according to Dr. Cowie.
“Health care providers should be aware of the increased risk of hearing impairment,” said Dr. Cowie, who notes that there are handheld devices that healthcare professionals can use to screen for hearing loss as a first line test, as well as written and online self-screening tools available to consumers.
“If there is some degree of hearing loss, the patient can be referred to ENT physicians or audiologists for further testing,” said Dr. Cowie, “Treatment options may include hearing aids, telephone-amplifying devices, and other tools.”