The National Institute on Deafness and Other Communication Disorders (2015) presents the following statistics on its website:
I am always surprised when patients (some in their 80s or 90s) walk into my office and tell me they never have had a hearing screening or hearing test. The Centers for Disease Control and Prevention (2015) estimates that, of the 29.1 million (9.3% of) Americans with diabetes in 2012, 8.1 million were undiagnosed. As hearing health providers, we need to be alert to undiagnosed hearing health problems. We can sometimes also perceive the beginnings of a metabolic problem in the results of a simple pure tone test, the audiogram shaped like a "cookie bite."
Hearing loss and diabetes are very common disorders affecting many millions of people worldwide. A major study (Bainbridge, Hoffman, & Cowie, 2008) confirmed a strong relationship between hearing loss and diabetes. Both diabetes and hearing loss are health conditions that can be screened or tested for easily and quickly. Unfortunately, these disorders often remain undetected until the patient has an "incident," forcing the need for an evaluation. In the case of diabetes, the patient may feel unwell and go to the emergency room. With cases of hearing loss, the patient may first notice not being able to understand conversations at social gatherings.
Does the following story sound familiar?
My patient—I will name him Joe—was in his mid-40s. He had not been feeling well for a while, but had difficulty pinpointing just what his medical problems were so that he could get help. He had mood swings. He often felt dizzy and disoriented. He also experienced frequent thirst. He knew where every bathroom was in any place he went, because he had to use one at least every hour. He also needed to use the bathroom many times at night, which disturbed his sleep.
One day, after 3 years of experiencing these symptoms, Joe traveled to see his children. After a 6-hour drive, he sat down to have dinner with his family and found that he had no appetite after a few bites. Within 15 minutes, he was also experiencing flu-like symptoms. He felt feverish, and his body ached. He thought he might have a virus and went to bed. Two hours later, he was feeling worse. It was suggested that he go to an urgent care center. After performing a number of tests, the physician at the center came to see Joe. In a matter-of-fact tone of voice, he said, "You have diabetes." Joe was in shock. He knew very little about diabetes and thought he might die quickly from the disease. He was given no further information about diabetes, but only instructed to see his primary care physician upon returning home. Back home, with the help of his physician, an endocrinologist, and a nutritionist, Joe took control over his diabetes with medication (pills), diet, and exercise.
A few years later, Joe noticed that he was having difficulty understanding speech in noisy environments. His feelings were classic for people who develop hearing loss. He felt embarrassed at social gatherings. He was being told by others that he sometimes misunderstood words. He became uncomfortable knowing that he was missing important information in group situations. An audiogram revealed hearing loss in both low and high frequencies, with normal hearing in the middle frequencies. The shape of this audiogram suggested metabolic involvement.
There are different types of diabetes. Type 1 generally consists of an autoimmune response in which the body does not produce enough insulin. As a result, the patient needs to take insulin daily depending on the body's needs. Type 1 typically affects children and young adults. Type 2 occurs when the body does not make enough insulin or cannot effectively utilize the insulin produced. Type 2 generally affects adults. About 90% to 95% of individuals with diabetes have type 2. Diabetes affects the circulatory systems throughout the body, causing progressive and/or permanent damage. It is a major cause of heart attacks, strokes, lower-limb amputations, kidney failure, and hearing loss. In an article about type 2 diabetes and hearing loss (Hong, Buss, & Thomas, 2013), the authors stated that more than 8% of the American population has type 2 diabetes, that the disease is increasingly prevalent, and that, by 2050, one in three Americans will have diabetes.
Recently, there has been a lot of interest in trying to discover how diabetes affects the auditory system and its role in contributing to hearing loss. Some of the current research is aimed at discovering the effects of a reduced blood supply going to all parts of the auditory system. The type of hearing loss most commonly seen in the population with type 2 diabetes is presbycusis—bilateral high frequency and sensorineural hearing loss. The loss is permanent and is usually progressive. Audiogram results from large populations of people with diabetes have shown that hearing loss can affect both low and high frequencies, resulting in the "cookie-bite" or metabolic audiogram.
Elevated blood sugar levels (Frisina, Mapes, Kim, Frisina, & Frisina, 2006) can cause chemical changes that impact the nervous system. As a result, the nervous system's ability to send normal sound signals to the brain is reduced. Bainbridge and colleagues (2008) looked at data from a large population to investigate the epidemiological causes of diabetes-related hearing loss in the United States. Audiometric data was taken from 1,508 patients, ages 40 to 69. The diabetic HbA1c, glycosylated hemoglobin test, was used to determine how well the diabetes was controlled and to know which patients were in the normal range. The HbA1c test looks at blood sugar levels over the last 3-month period. A value under 7.0 is considered normal or good control. Numbers over 7.0 indicate increasing risk for complications. The patients were tested at pure tone frequencies of 500Hz and 1000–8000kHz. Those with diabetes were found to be twice as likely to develop hearing loss as the control group, with a significant gradually progressive loss as patients aged.
Because of the complexity in treating diabetes, it is important to establish a management team for these patients. The ideal initial management team would consist of a primary care physician, endocrinologist, cardiologist, audiologist, speech-language pathologist, ophthalmologist, podiatrist, psychologist, diabetic educator, and exercise trainer to help prevent further diabetic deterioration and resulting complications. Unfortunately, audiologists and speech-language pathologists are generally not included as part of the management team.
It is extremely important for the patient to take control of his or her diabetes. Hearing loss generally affects increasing numbers of people as they age; this is especially so for the diabetic patient population. Just as there are routine yearly eye exams, patients with diabetes should have routine yearly hearing screenings/tests. Results should be sent to the rest of the patient's management team so care can be coordinated. In a clinical study (Sunkum & Pingile, 2013), the authors stressed that the diabetic patient has more problems not only controlling the disease over time, but also avoiding hearing loss, which is accelerated, especially if blood sugar is not kept under control with prescription medicines, diet, and exercise. Lin (2012) found that patients with hearing loss who were left untreated developed dementia more frequently than did the control group. Compared with people with no hearing loss, those with mild hearing loss were twice as likely to have dementia; those with moderate loss, three times more likely; and those with severe loss, five times more likely. Because individuals with diabetes are more likely to develop hearing loss, the audiologist should serve as an important member of the patient's management team.
As part of taking an initial medical history, audiologists and speech-language pathologists should always ask new patients if they have diabetes. If the answer is "yes," patients should be asked whether their diabetes is under control and for their most recent HbA1c number. It is important to keep a current list of medications in the case file. Questions should be asked about family medical history. Does the patient know whether grandparents, uncles, aunts, sisters, or brothers have diabetes? Our patient Joe realized that his deceased parents might have had diabetes. They had both experienced mood swings, becoming angry and upset at a moment's notice. They would suddenly fall asleep at meals or while sitting in the living room or in the car. They had never been tested for or diagnosed with diabetes.
Diabetic patients with hearing loss who are 50 or older need to be tested and fitted with hearing aids. Post hearing aid fittings should be followed up with aural rehabilitation, when appropriate. The team should also be involved in counseling, so that the patient will be more actively involved in his or her care. Untreated hearing loss can result in mood swings exhibiting as sadness, depression, and paranoia (unpublished observation). Individuals with hearing loss can become socially isolated, emotionally insecure, and easily upset. When hearing sudden noises, such as a person approaching from behind, patients with hearing loss can startle easily. Proper amplification will help the patient hear environmental noises and speech more clearly, resulting in less irritation, anger, and misunderstanding. The patient should also be counseled in the use of hearing protection during exposure to very loud noises (e.g., at concerts or social events or produced by commercial equipment, including landscaping and snow removal machinery).
Because so many people are affected by the common disorders of hearing loss and diabetes, there should be greater public educational/informational efforts about care and control of these conditions. Screenings or hearing tests are easily available but need to be well publicized. More research is necessary to determine how diabetes, which is thought to be a microvascular disease, interacts with and affects the auditory system. Research also needs to further our understanding of how the auditory system processes auditory information and how diabetes affects hearing and central auditory processing. Patients and their health care professionals need to be proactive to prevent these disorders from progressing more quickly. The end results are better health and a much improved quality of life.
Marilyn Enock, AuD, CCC-A, is a Julliard School of Music trained violinist. She received her BA from Hunter College in New York. She obtained her MS in communication sciences (audiology) at the University of Pittsburgh. Her doctorate is from A. T. Still University of Health Sciences. She has been in the field of hearing health care since 1970. She started her private practice A Better Hearing Experience in Pittsburgh, Pennsylvania, in 1999 and continues to practice. Contact her at firstname.lastname@example.org.
Bainbridge, K., Hoffman, H., & Cowie, C. (2008). Diabetes and hearing impairment in the United States. Annals of Internal Medicine, 149, 1–10.
Frisina, S., Mapes, F., Kim, S., Frisina, D., Frisina, R. (2006). Characterization of hearing loss in aged type II diabetics. Hearing Research, 211, 103–113.
Hong, O., Buss, J., & Thomas, E. (2013). Type 2 diabetes and hearing loss. Disease-a-Month, 59, 39–46.
Lin, F. (2012). Hearing loss in older adults—who's listening? Journal of the American Medical Association, 307(11), 1147–1148.
National Institute on Deafness and Other Communication Disorders. (2015). Quick statistics. Retrieved from www.nidcd.nih.gov/health/statistics/Pages/quick.aspx.
Sunkum, A., & Pingile, S. (2013). A clinical study of audiological profile in diabetes mellitus patients. European Archives of Otorhinolaryngology, 270, 875–879.
U.S. Centers for Disease Control and Prevention. (2015). 2014 national diabetes statistics report. Retrieved from www.cdc.gov/diabetes/data/statistics/2014StatisticsReport.html.