Approximately 9 million Canadians live with a type of diabetes or prediabetes. Diabetes is a group of diseases characterized by high levels of blood glucose due to a fault in the body to produce or use insulin properly. Diabetes is classified as a metabolic disorder, which affects the body’s normal responses. This disease can affect many different systems in the body, including the auditory system.
The link between hearing loss and diabetes has been known for many years. The National Institute of Health has found hearing loss is twice as common in adults with diabetes compared to those without the disease. Even people who are labeled as pre-diabetic have a thirty percent greater chance of hearing loss than people with normal blood glucose levels. This relationship remains, even with other hearing loss factors (eg. age, noise exposure, etc.) taken into account. With high incidence numbers like these, it would seem like more people with diabetes would be aware of the connection; however, that is not the case. As diabetes often seems to be associated with age, many people believe the hearing loss they may have is due to increasing age. The link between hearing loss and diabetes is not often made.
Diabetes can potentially affect three systems in the ear. First, diabetics tend to lack a protein called keratin that forms a protective layer in the ear canal. Without this layer, the ear canal tissue can become over stimulated, potentially leading to hearing problems. Second, one of the hearing organs, the cochlea, can experience a loss of hair cells. The hair cells are responsible for responding when sound enters the ear and sending the signals to the brain. Without the hair cells, some signals may not be transmitted or transmitted properly. Finally, nerve damage can also develop. Nerves are responsible for sending the information that is heard to the brain. High blood sugar levels cause chemical changes in the nerves, affecting their ability to transmit signals.
People with diabetes often develop a sensorineural hearing loss. That type of hearing loss affects the auditory nerve, sending incomplete signals to the brain. This type of hearing loss often results in people reporting that words/sentences are not clearly heard. One reason the link between diabetes and hearing loss is often not made is the type of hearing loss caused by diabetes is the same type of hearing loss due to aging. Hearing loss due to aging, known as presbycusis, also results in a sensorineural hearing loss. Therefore, it is often assumed that a sensorineural hearing loss is due to aging and other causes are not often examined very closely.
So now that the reasons behind the hearing loss have been examined, what can people with diabetes do? First, the most important thing may be to disclose their diagnosis to their health care providers. As mentioned above, the link between hearing loss and diabetes often isn’t made, usually because the health care professional is unaware of the diagnosis of diabetes. If the person’s audiologist or hearing health care provider knows of the presence of diabetes, the hearing loss would not be presumed to be due only to age. It would be beneficial for people with diabetes to have regular hearing screenings. The other thing that people can do is closely monitor their blood glucose levels. There is some evidence to show that people who are able to manage their blood sugar levels well may not experience the same degree of hearing problems as those whose diabetes is not as well managed. Closely monitoring and managing the diabetes may help to ward off the effects of hearing problems.
Any concerns a person may have regarding diabetes and hearing loss should be discussed with their hearing health care provider or physician.