Editor’s note: This text-based course is an edited transcript of the webinar, Audiology: Diabetes in Hearing & Balance Care, presented by Kathy Dowd, AuD.
After this course learners will be able to:
- Describe the pathophysiology of diabetes on the cochlea and vestibular canals, neural systems and perception of hearing and balance.
- Explain how audiology medical management will ensure the best patient outcomes for diabetes care.
- Explain how to work toward interprofessional education and collaboration in their state and local venues for the inclusion of audiology in diabetes care.
Today I'll review the pathophysiology of diabetes on the cochlea and the vestibular canals, as well as on the neural system. The result is a disruption in the perception of hearing and in balance, which increases risk of falls. I'll explain how audiology medical management will ensure the best patient outcomes for diabetes care. I'll also cover how to work towards interprofessional education and collaboration in your state and in your local community for the inclusion of audiology in diabetes care.
Diabetes in the Body
What is happening in the body with diabetes? Keep in mind that what is happening in the cochlea and the vestibular system is also happening throughout the body when someone has diabetes. Diabetes causes microangiopathy, or small blood vessel disease (SMD). With small vessel disease, blood vessels weaken and slow the flow of blood through the body. This may lead to organ and tissue damage and result in loss of function or diabetic neuropathy.
When you look at the effect of diabetes on the cochlea, there's a disruption in the microvascular system as well as neural degeneration. The VIIIth cranial nerve innervates both the cochlea and the vestibular system. Diabetes affects the neural system, not just for the ear and balance system, but throughout the body. A person with diabetes is also more susceptible to infections. In addition, there's a domino effect with other chronic diseases. It's not unusual for someone who had cardiovascular disease to be diagnosed with diabetes later in life. Or, vice versa - if someone has diabetes, they may later get diagnosed with cardiovascular disease. Chronic kidney disease is another issue that may be associated with diabetes, as well as Alzheimer's disease.
It takes nine to 12 years to identify diabetes or prediabetes. There is a long lag where a person has no idea that they have diabetes or prediabetes, and all the while it is causing disruption in their body or damage to their body. The dental profession is looking at including identifying diabetes with their patients as part of their scope of practice, which is a great step forward.
The brain is the receptor for all the neural transmission in the body. Microangiopathy, the disruption in small blood vessels and neural degeneration, happens throughout the body. One interesting fact about diabetes is that people with diabetes have more broken bones, but not from osteoporosis or osteopenia.
In the standards of care for diabetes, there is no mention that this may be associated with risk of falls. As audiologists, we have to ask ourselves, are the broken bones resulting because the person is at a higher risk for falls? In addition, there has been a lot of discussion over the last five years about hearing loss being associated with advancing age. The National Academy of Science, Engineering, and Medicine came out with a 400-page report in 2016 stating that hearing loss was due to advancing age. My sense of what's happening with these chronic diseases is, yes, with advancing age, you get an increased prevalence of chronic diseases because you have a weakened immunity with advancing age. In addition, you are getting more potentially ototoxic medications over time to deal with pain and infection. The risk of falls may be due to losing your vision with diabetic retinopathy, and from neuropathy in the feet that causes a lack of feeling in the feet. And, there are also vestibular issues that come with diabetes. In addition, there's an increased prevalence of hearing loss with cardiovascular disease and chronic kidney disease, and we know these diseases are associated with diabetes. So, is it age alone that's causing hearing loss and risk of falls? Or, is it because older people have weakened immunity and an increased prevalence of chronic diseases, which create a cascade effect?
Why is Hearing Loss Not Easily Detected?
You cannot just observe a person and know they have a hearing problem, unless maybe the hearing loss is severe. But hearing loss is not usually easily detected. One confounding factor is anosognosia, which is the inability for a person to know that they have a sensory impairment. The patient has a lack of awareness and therefore doesn't recognize the signs or the symptoms of the illness in themself. Anosognosia is not merely a denial; it is an actual neurological deficit of self-awareness. An excellent book that addresses this topic is, "I'm Not Sick, I Don't Need Help!" by psychologist Dr. Xavier Amador. Dr. Amador discusses a time in his residency when he was first seeing a patient who had had a stroke. He said to the patient, "Well, I understand that you don't have any use of the right side of your body." And the patient said, "No, no, I'm fine. I'm ready to go home. I want to get out of here." He said, "No, you're not able to walk - you had a stroke and you can't move the right side of your body." And she said, "No, I'm fine." He then asked her to raise her right arm up off the bed. He waited a minute, and nothing happened. And he said again, "Raise your arm up off the bed." And she said, "I did." He said, "No, look at your arm and raise it up off the bed." And she looked at her arm, and it didn't raise up. And she looked back at him and she said, "You're holding it down." He explained that he was not holding her arm and that she couldn't lift it due to a stroke. But in her mind, she still had the capacity to physically move her body. She was totally unaware of the stroke effects. This is similar to what happens with hearing loss. A person with a hearing loss says, "No, my hearing is fine." It could be their perception since they do still hear certain aspects of speech, such as low-frequency sounds or vowels but they don't hear the high-frequency consonant sounds. Perhaps low-frequency sounds are perceived at a loudness level that seems normal so the patient feels hearing loss is not a problem. They may blame the "young people who just don't know how to speak clearly anymore" and they may report that others are mumbling.
The Centers for Disease Control and Prevention (CDC) started measuring the incidence of diabetes in 1990. They began a Translation Advisory Committee in 1993 to try to control the effects of diabetes. They first released data on the age-adjusted prevalence of diagnosed diabetes in U.S. adults in 1994. And in 1995, the American Diabetes Association's clinical practice recommendations included a referral of persons with diabetes to doctors of optometry for an annual vision evaluation.
You can look at the prevalence of diabetes by state for each year since 1994 on the CDC website. If you do this, you will see the prevalence increasing and the differences between states. In 1998, they reported the prevalence of diabetes to be 6.5%, which was an increase of +33% from 1990. By the year 2000, we started to see an epidemic with diabetes in the U.S., with many states (particularly in the southeastern U.S.) having a prevalence of 9% and greater. Today, the majority of U.S. states have a high incidence of diabetes. Remember, it takes nine to 12 years to identify diabetes and prediabetes. The CDC data is the diagnosed incidence of diabetes, or patients with diabetes. It does not include those who have diabetes but have not yet been diagnosed. You can view these maps at CDC.gov and access 2020 CDC data on diabetes at this link (copy and paste the link into your browser): https://www.cdc.gov/diabetes/pdfs/data/statistics/national-diabetes-statistics-report.Pdf
Diabetes and Hearing Loss, Vision
With diabetes, a person has high blood glucose that damages the inner ear due to microangiopathy, or small vessel disease. The mechanism of damage is similar to the way that diabetes can damage other organs such as the eyes and the kidneys. Small blood vessels are throughout the ear including the inner ear and the vestibular system. Even the eardrum includes a network of small blood vessels.
If you understand how diabetes impacts vision, you will have an understanding of what's happening in the cochlea when a person has diabetes. The other issue that complicates matters when it comes to the ear is that the cochlea is a little black box. What I mean by that is that you can't look into the cochlea like you can look into the back of the eye for signs of diabetic retinopathy.
In the ears, the small blood vessels may grow new tendrils in the ear and in the vestibular system, or leak blood into the endolymph and the perilymph of the cochlea. Endolymph and perilymph have chemical compositions that actually help aid the synapses to send the sound signal along the neural pathway to the brain. When blood is mixed into this space there is an effect on hearing. Uncontrolled diabetes has a very significant impact and there is a lot of research on this issue when it comes to hearing and balance.
Balance and Diabetes Care
Diabetes also affects balance. We know that poor balance contributes to falls risk or the fear of falling. If you have a risk of falls, it contributes to a lack of exercise. Falling also leads to potential bone fractures and impedes diabetes care. If you are not comfortable getting out of your house and walking due to fear of falling and breaking a bone, you may miss appointments for diabetes education. You may even miss going to the doctor for healthcare follow-up appointments. Falls are a very costly medical expense in the United States.
It's important to know what's causing the risk of falls in diabetes. Where does the vestibular impact of diabetes occur? With hyperglycemia, there is too much blood in the sugar and there is a formation along the protein pathway. There's an overproduction of extracellular matrix and increased lipid droplets and lysosomes in the connective tissues of the utricle and saccule of the vestibular system. There is impaired diffusion of oxygen and nutrients and waste, and degeneration of type 1 hair cells in the vestibular system. Hyperglycemia causes glycosylation of the myelin. The myelin is the coverage of the nerve, the myelin sheath of the nerve. The lysosomal digestion of large portions of the vestibulocochlear (VIII) nerve, myelin sheath thinning, and reduced axonal fiber diameters causes vestibular dysfunction. There is a longer latency and reduced amplitude of vestibular evoked potentials. Again, the American Diabetes Association standards of care lists bone fractures as a comorbid condition of diabetes, but it does not mention the risk of falls. We need to educate more people on this issue.
Chronically high blood sugar levels damage the nerves not only in your extremities but also in other parts of your bodies. The damaged nerves cannot effectively carry messages between the brain and other parts of the body. Balance is complex, and the parameters affected by diabetes include: vision loss, loss of sensation in the feet, and vestibular disruption.
When you look at maintaining balance, you have to consider vision. Can the person see in front of them and know where to step and what's on the floor in front of them? Do they have a loss of sensation in their feet? If they can't feel their feet, they may be stepping on a surface that isn't level, and it will cause them to fall. Vestibular disruption also plays a role in persons with diabetes. Remember that diabetes affects the whole body.
Consider the pathophysiology of the hearing and vestibular system. A signal comes into the ear and is transmitted by outer hair cells and inner hair cells and delivers a synapse which is picked up by the VIII nerve and travels the brain. The vestibular system determines your orientation in space. Are you standing up? Are you laying down? Are you starting to fall? When sound travels from the cochlea to the pons, the medulla oblongata, and 85% of what you hear in one ear travels to the other side of your body and is perceived on the other side of your brain. If you're hearing on the right ear, 85% of the signal goes to the left side of your brain and vice versa. Any impact on the sound synapse occurring in the cochlea or the vestibular system is going to impair the signal traveling along the nerve. If the nerve is losing its ability to transmit the signal, then the brain will not get a clear signal. The inner ear can have effects from microvascular damage from diabetes or macrovascular damage from cardiovascular issues.
Ototoxicity and Vestibulotoxicity
Persons with diabetes may take medications for pain, infections, other diseases, and we need to consider whether those medications are toxic to the ear and the vestibular system. With neuropathy, although there is a lack of sensation, there may also be a burning sensation. A person may feel their feet burning, and they may be in pain and take pain medication such as aspirin, salicylates, NSAIDs including ibuprofen. These and other medications may have a potentially damaging effect on the ear. Persons with diabetes have a higher risk of infection and infection-control medications, such as aminoglycoside antibiotics, can have a potentially devastating effect on hearing and the vestibular system.
Patients who take or have taken a mycin drug (e.g. gentamicin, vancomycin, erythromycin, etc.) that are used to prevent or treat an infection have a potential to damage hearing for up to six months post treatment. When hearing and/or balance is impacted, the effects are permanent. When you look at Loop-inhibiting diuretics may be used for cardiovascular disease to manage fluid around the heart or extremities such as LASIX and furosemide. When loop-inhibiting diuretics are combined with aminoglycoside antibiotics there may be a synergistic damage on hearing and balance. In addition, chemotherapy drugs such as cisplatnum and carboplatnum have a deleterious effect on hearing.
Refer to clinical guidelines for monitoring and managing ototoxicity and educate physicians and nurse practitioners about this.
Audiology Medical Management of Hearing Loss for Persons with Diabetes
A baseline hearing test is an important starting point with every patient. At the initial test of a patient with diabetes, their hearing may be fine or they may have hearing damage unrelated to diabetes, such as from working in a very noisy occupation. The point is to have a complete picture of hearing at the time of diagnosis. If there is no hearing loss on a pure-tone audiogram but the patient has complaints about hearing, it may indicate a need for additional tests, like otoacoustic emissions (OAEs) or speech-in-noise (SIN) testing. The pure-tone audiogram is our standard for diagnosing a hearing problem, but now we know there could also be a hidden hearing loss where you may find deficits on other tests like OAEs or SIN. The case history will point to factors that are influencing potential hearing loss. What has this person been exposed to over the last 15 or 20 years? From there you will begin to build recommendations to the doctor or to the medical professionals that set a rationale for future monitoring and management for this patient.
If a patient has diabetes, this is very important: Always refer for diabetes education. Diabetes education is covered by Medicare. A person who's just diagnosed with diabetes can get up to 10 hours of diabetes education when they're first diagnosed, and it's covered. A diabetes educator or educational specialist will teach them how to eat right, how to exercise, how to check their blood glucose levels to help to manage their diabetes successfully. This information is critical for people with diabetes.
All chronic diseases like diabetes and co-morbidities with hearing loss need to be managed and I recommend the article by Dr. Victor Bray entitled, A holistic approach to managing hearing loss and comorbidities. You need to take a thorough case history. Ask questions to try and determine the cause of the hearing loss, medications they are currently on or have taken, and other chronic diseases the patient is managing. If they went in for a hip replacement or a knee replacement, keep in mind that a lot of those artificial joints have gentamicin in them. Is that affecting hearing in any way? If the person has hypertension, high blood pressure, or cardiovascular disease it is important to note. Ask why they are taking the medications they are taking as it may help you to learn of additional conditions that are being treated. What hospitalizations have they had in the last 10 to 20 years? All of this has relevance in determining the impact on hearing. Ask about occupational noise exposure and recreational exposures such as guns/shooting, chainsaws, and leaf blowers. People don't always consider that these common activities can damage hearing. I had one woman who had a significant loss, and it looked very much like noise exposure. She was a nurse and denied being around any noise. So I said, "Lawnmowers, leaf blowers, chainsaws?" She said, "Oh, I use a leaf blower every day." I said, "Why?" She said, "Oh, I blow the leaves off my deck." Without hearing protection, this may be a risk for hearing loss. Ask about complaints of hearing or balance issues and be sure to document your findings.
The audiological evaluation should include the pure tone audiogram via air conduction and bone conduction, as well as suprathreshold word recognition testing. Consider speech-in-noise testing like the QuickSIN test, as well as otoacoustic emissions testing.
Conduct a balance screening. It is not recommended that we do a balance assessment for every person who's diagnosed with diabetes, but it is important to ask some questions. The balance screening can be very simple. Have you fallen in the last few months? Do you have a fear of falling? Do you have a vision problem? Do you have neuropathy in your feet? If you're an audiologist and you're doing a vestibular workup, make sure you check for neuropathy. You want to know if the other sensory issues are impacting balance and risk of falls. Most commonly, VNG is conducted while sometimes cVEMP, oVEMP, rotary chair testing may be conducted. But again, keep in mind foot neuropathy. Because I've heard of people getting "cleared" by the audiologist, and the reason for the falls is still unknown but turns out to be foot neuropathy. It's a very simple screening question that you can ask.
In terms of recommendations, think about how often you will need to monitor the person based on the information you collected during the testing and case history. As discussed, make a recommendation on your report to refer for diabetes education. Perhaps the primary physician has not done that as they are very busy and it may be an oversight so you can remind them of that. It may be that your test results require amplification for the person with diabetes. And if the person is at risk for falls, then there are many fall prevention clinics that are opening around the United States including state agencies that are supporting fall prevention. Research resources in your state and contact your fall prevention coordinator to find out what resources are available. Also, one other point on making a recommendation, if the person is not taking their medications, make sure you make a note for the physician to speak with the patient about it. Maybe the patient said, "Well, I don't feel anything when I take my blood pressure medication." They most likely need to take all prescribed medications so it is important to follow up when the patient reports otherwise, and I'll mention this again in the next session regarding professional collaboration.
Professional Collaboration to Manage Diabetes
We have to work together with other professions to manage diabetes. We want to give consistent diabetes messages to the person with diabetes. They need to recognize danger signs. If they're losing their vision, maybe that means their diabetes is more out of control. They need to be checking their blood glucose. Promote a team approach to care. Integrated, comprehensive care benefits everyone. The CDC includes allied health professions of pharmacy, podiatry, optometry, dental, and audiology as being important in diabetes care. Remember to include diabetes educators, also.
Let's circle back to this important point - Are your patients taking their medications? In the United States, 15% of prescriptions are never filled. And 50% of patients stop their prescription regimen within six months. It may be due to not having the money for the prescription, or other factors. Discuss this with your patients. Why have you stopped taking this medicine? Every single pharmaceutical company, if you search it on the internet, has a way for people to get free prescriptions. There is an application on their website and it's a very simple process. Link up with a pharmacist so you can relay to the pharmacist, this person may need some help in getting coverage for their medications. People see their pharmacist seven times more frequently than any other medical professional. So make sure you know the pharmacists around your clinic and in your commuinity.
Podiatry and Foot Care
More than 60% of nontraumatic lower limb amputations occur in people with diabetes. Patients with diabetes are 15 to 26 times more likely to have an amputation than patients without diabetes. Up to 20% of diabetes patients who participate in routine foot care will have a treatable foot care problem. I listened to a talk in Michigan by an infection control clinic. They said for everyone who came in to be treated for infections, they always X-rayed their feet. And they discovered one woman had a sewing needle stuck up her foot. They pulled it out, and they showed it to her. And she said, "Oh, my heavens, that's where that went. I've been looking all over for it." But she had no sense that it was in her foot. Another person walking around the house barefooted had LEGO blocks embedded in the bottom of their feet. It's important to talk with your patients about wearing shoes, slippers, or footwear with a sole so they don't pick up things on their feet because they can't feel them. Objects stuck in the feet can cause an infection, a break in the skin, and eventually lead to amputations. About 15% of people with diabetes get a lower limb amputation.
Vision is far ahead of audiology, and even dental care as they've had guidelines for managing persons with diabetes since 1995. Make sure that your patients are getting their eyes checked on a regular basis. Ask these questions. If the answer is a no, or they're not sure, refer to an optometrist.
- Did you get a full eye exam with dilated pupils at least once a year?
- Do you know how diabetes can affect your eyes?
- Do you know what to do if you have vision changes?
There's one person in my area who was in her eighth month of pregnancy, and she developed gestational diabetes, and she suddenly went blind. She had been working up to this point. It was devastating. Now, her daughter's probably 10 years old and her vision has resolved somewhat. She still has diabetes, but is very cautious about her managing her diabetes, eating right and exercising.
Dentistry and Oral Health
Dentistry has just come on the landscape of diabetes care. Going to an annual conference in 2012, the topic of the day for diabetes educators was inclusion of dentistry. Approximately 85% of patients with type 2 diabetes report they have received no information on the association between diabetes and oral health.
After I went to that conference in 2012, I asked my own dentist, do you know about any links between dentistry and diabetes? He said, "No, I've never heard of that." I asked him again a few years ago. He said, "Oh, yes. We have standards of care. We're very watchful for any symptoms or problems." If you have periodontal disease associated with poor glycemic control, you can get infections in your body as a result. Tobacco use and poor nutrition are also risk factors for compromised oral health. If you're missing teeth, and you're not having good nutrition because you can't chew, that will have an effect on your total health, including your heart health and diabetes health.
Audiology and PPOD - Summary
For audiology, these are the things that we need to do to align with pharmacy, podiatry, optometry, and dental (PPOD). If we somehow could get the clinical guidelines of pharmacy to indicate that when a patient receives a prescription for gentamicin or vancomycin, an audiological baseline and monitoring is recommended. For podiatry, we have to collaborate for better foot care and balance care. Talk with your patients. Make sure they wear shoes. Make sure that they have somebody looking at the bottom of their feet. Make sure that optometry evaluations occur. We want to lower the risk of falls. We want people to be able to see. Counsel your patients with diabetes to see the dentist several times a year. There needs to be ongoing interprofessional education and interprofessional collaboration among audiology and all of these other allied health professional groups in state and local settings.
Family and Internal Medicine
The CDC wants to ensure that family physicians and internal medicine professionals are checking for diabetes. We can educate doctors on the consequences of having a hearing loss as well as the symptoms they may observe in their office. The doctor may recognize the symptoms if the person asks for repetition, or they bring a third-party interpreter or a spouse. The doctor may recognize that there seems to be some confusion, cognitive decline, depression. They may not that the patient is not getting out socially and seems to be isolating themselves.
The family doctor and the internal medicine doctor need to know that these are symptoms of, potentially, a hearing loss in addition to the chronic diseases and the medications. If the person has an invisible handicap of hearing loss, they are going to miss the verbal instructions that the doctor wants them to follow. And therefore, they didn't understand. They are more likely to be noncompliant with the medical directions, and therefore the doctor will have worse patient outcomes. There is value for the doctor to know if there's a hearing problem.
Hearing Screening Starts the Process
Hearing screening starts the process. hearScreen USA is an online screening that takes three minutes. You have to plug in headphones and can run it off of a laptop, tablet or an iPad, or even your telephone. Make sure you use headphones, and make sure you're in a quiet place. It is a digits-in-noise test and gives you a pass-fail. If you're audiologist, this is something that you can put on your own website. It costs about $300 a year, but then you can share it with area physicians. You can have a place at the bottom where, when somebody fails, the nurse just goes ahead and makes the referral on this site to you. It is a very important screening tool, and I hope that you will use it.
Educate About Audiology
Educate people about audiology. As recently as 2011, the CDC had never heard about the effects of diabetes on hearing and balance. We need to explain to medical professionals what we do in conducting audiology evaluations and management of hearing. We do balance screening and evaluations. We do treatment of hearing loss and balance problems, but sometimes we refer to physical therapy for the treatment, depending on the clinic setting. We counsel the person for social, job-related, and personal communication. If a person is having difficulties hearing on the job we can help them find solutions. We also have specialties in tinnitus management, cochlear implants, and pediatric specialties. All of this is very important for other professionals to understand audiology and what we do.
Advocate for audiology with this emerging issue of diabetes. Join a state cohort or country cohort. If you want to advocate and educate people about the effects of diabetes and chronic diseases, go to www.theaudiologyproject.com and submit a Contact Us form and we will connect with you.
Reach out to your national, state, and local agencies and groups to educate them about what audiologists do. Offer to present to their group counsels. The Audiology Project can provide you with presentations. We also have webinars on our website that you can show for free when you have to go and speak at a medical society at a hospital that meets once a month. We have other resources as well.
Align with PPOD (pharmacy, podiatry, optometry, and dentistry) in your state and your local community. How can you have synergy to make sure that people get the best diabetes care? Refer your patients for diabetes education. Diabetes educators are the linchpin of diabetes care. They are no longer called certified diabetes educators, but they recently changed their title to DCES, which stands for Diabetes Care and Education Specialist. They are wonderful. They will help tie up all the loose ends for your patient with diabetes.
Another helpful resource for your outreach and education efforts is this YouTube video of a hearing loss simulation using a Flintstones cartoon (copy and paste the link into your browser): https://www.youtube.com/watch?v=Va1wrnsMve0
These kinds of practical tools do make a difference in helping people to understand more about hearing loss.
Educate Yourself About Diabetes
Educate yourself about diabetes. Know the ABCs of diabetes. Know what A1C is. Know how it is important to control blood pressure, control cholesterol, and to stop smoking. I was ignorant in the very beginning. An audiologist with diabetes educated me on some of these things. Educate yourself so you can educate your patients.
I've included some helpful references in the course handout. In addition, we just finished a two-year project to write an issue of Seminars in Hearing. On our website, www.theaudiologyproject.com, you can download helpful publications. There are also research articles, the hearing screening app, and helpful links for you and your patients.
Dowd, K. (2020). Audiology: diabetes in hearing & balance care. AudiologyOnline, Article 27259. Retrieved from https://www.audiologyonline.com