"Do you have diabetes?" I asked, as is my routine practice during a recent audiometric evaluation.
"How did you know?" demanded the 67-year-old patient as he sat straight up in his chair.
"How did I know what?" His uncharacteristic, almost angry, response had so startled me that I wasnt sure we were talking about the same thing!
"Why did you ask me if I had diabetes?" He said accusingly. "Oh, I know. You noticed my shoes!" pointing to his spotlessly white, top-of-the-line running shoes.
"No, I had no idea you had diabetes, nor did I associate your shoes with the condition. This is simply a routine question we ask anyone receiving a hearing test."
"Nobody else thats tested my hearing has asked me about that. What does diabetes have to do with my ears, anyway?"
Admittedly, I was thrown off by this gentlemans aggressive, almost offended, reaction to my routine question. It was as if he had a pent-up frustration built around his hearing impairment and his diabetic condition. As it turned out, he had unsuccessfully tried hearing aids for his hearing loss at three previous clinics. Apparently, in each case, no connection was drawn between his diabetic condition and his advancing hearing loss.
I explained to him that diabetes mellitus II (see below) has been found to be a strongly associated health factor in hearing health. Some of the known associations between diabetes and hearing issues include:
A- Missing or abnormal keratin protein, which comprises the protective layer over the ear canal tissue that helps the ear maintain proper pH flora. Additionally, keratin protein allows earwax to travel outward, and cushions at least four neuro-reflexes of the external ear canal from over-stimulation.
B- Hypersensitivity of the ear canal skin to earmold and hearing aid plastics due to atrophy of epithelial tissue in the ear canal (this may be accommodated by ordering hypoallergenic or non-allergenic materials).
C- In "low pH" situations, the ear canal tends to experience chronic irritation, fungus, yeast, and, in stubborn cases, pseudomonas irritation and/or infection (otitis externa) when the canal becomes anaerobic (air circulation closed off due to wearing an earmold or hearing aid). Management by a physician may prove necessary.
D- Higher-than-usual incidence of recruitment (abnormal loudness growth and over-sensitivity to loud sounds), which may be accommodated by one or more compression strategies (WDRC, AGCo, AGCi, etc.) in todays digital or hybrid programmable hearing aids.
E- Vestibular problems (dizziness, vertigo) may arise, one of the red flag conditions warranting medical referral.
F- Hypersensitivity of the vagus nerve (a branch of nerves which communicates nausea from the stomach area among other artifacts) may be somewhat affected if the earmold or hearing aid is too tight for comfort.
G- Neuropathy, which is typically a root cause of blindness and amputations associated with diabetes, can also produce problems in the neurological system of the human ear. This causes a high incidence of central auditory dysfunction in both receptive (speech understanding) and expressive (speech) communication. Non-recognition of this possibility may cause the patient and professional to have unrealistic expectations upon the success or necessary timeline to achieve auditory rehabilitation.
PREVALENCE OF DIABETES MELLITUS: Number of Persons Diagnosed with Diabetes in the USA.
Recognized cases of diabetes mellitus (those reported to the Center for Disease Control) number approximately seventeen million in the U.S. today. People aged 65 years or older account for almost 40% of the diabetic population (CDC). It is commonly understood that many more cases go unreported or undiagnosed.
Consequently, numerous studies show an inordinately high incidence of hearing loss among diabetics, roughly 80%, particularly with progressive sensorineural (nerve) high-frequency bilateral hearing loss. What may be disguised as a classic case of presbycusis (hearing loss associated with aging) or acquired hearing loss may, in reality, be associated with a diabetic condition.
One may safely assess that the veritable and interconnected associations between diabetes and hearing loss are considerably more than the statistics reveal. This fact underlines the need for every person who receives a hearing evaluation to also receive a thorough health assessment and case history.
TYPES OF DIABETES MELLITUS
Diabetes mellitus is characterized by abnormally high levels of blood sugar (glucose) in the blood and the urine. It occurs when the body does not produce adequate quantities (or quality) of the hormone insulin, which is produced and secreted by the pancreas. When a person has diabetes, their body is unable to absorb glucose. Therefore, glucose remains in the bloodstream and is passed out of the body through the urine.
There are two main types of diabetes mellitus:
Type I diabetes, or insulin-dependent diabetes, occurs when the body doesnt manufacture insulin. Type I is generally recognized as ''juvenile diabetes'' although it may occur at any age. This type of diabetes can be life-threatening. Left untreated, ketoacidosis develops. Ketoacidosis can be very dangerous, can essentially poison the body, and may lead to diabetic coma or death. Ketoacidosis doesnt occur with type II diabetes.Ketoacidosis essentially means dangerously high levels of ketones. Ketones are acids that build up in the blood and theyre present in urine when not enough insulin is present in the body). Ketoacidosis can cause any number of health problems, including blindness, weight loss, neuropathy, loss of resistance to disease, or death. Type I diabetes is managed with daily insulin, diet, and control of body energy. The relationship between hearing loss and Type I has been found in numerous studies (see bibliography below).
Type II diabetes (non-insulin dependant) is the most common type, occurring in about 90 to 95 percent of all people diagnosed with diabetes. Type II primarily affects adults, especially those over 40 years of age. More women than men experience this type of diabetes, and it tends to run in families. In these cases, the pancreas produces insulin, but not the type, pH or quality needed by the body. Therefore, a combination of oral hypoglycemic drugs, diet, exercise, and weight control is the usual course. Advances in science and clinical management have become so sophisticated compared to just a few years ago, that we cannot do justice in describing treatment approaches here. Type II is associated with overweight (hyperlipoproteinemia) in about 80% of cases, because when insulin (in any form) is overstimulated it prevents the body from burning fat. Only its counter-hormone, glucogen, can keep weight under control. Some programs focus on not only controlling excess blood sugar but also in controlling over-secretion of insulin.
The connection between Type II diabetes and hearing loss has been well established in the literature. However, because of aging and other health factors, the connection can sometimes be obscured in routine medical diagnoses.
NEED FOR RECOGNITION & ACCOMMODATION:
As noted above, associated affects of diabetes upon hearing loss and hearing aids include tissue hypersensitivity and an inability to fight off infection. This presents a complex set of challenges for many diabetic hearing aid patients. For only the most non-allergenic earmold materials must be utilized. Ergonomic aspects of the fit must be precise and accommodate the dynamics of the ear, including mandibular movement. Recognition of these factors can be critical, and may require interaction with other professionals.
Another consideration is abnormalities affecting cochlear microphonics (function of the inner ear). The cochlea converts hydraulic vibrations into electrical impulses carried by the neural system of the auditory nerve. To produce a proper level of electrical charge (called cochlear potential), there must be precise pH balance of the two inner ear fluids: 90% potassium and 10% sodium (endolymph), and 90% sodium and 10% potassium (perilymph). A change in this balance of +/- 1% can adversely affect frequency and loudness growth perception, as well ones equilibrium (balance).
Hypertension, microvascular constriction, and other fluid abnormalities may have a direct effect upon the inner ear, sometimes exacerbated by overly aggressive medical regimens designed to control blood pressure. When the bodys pH balance is abnormal (either too much acid or alkalinity) or proper fluid level and circulation is affected as a result of fluctuations in the diabetic condition, changes in loudness growth perception and in auditory function occur.
For this reason, the diabetic hearing aid users inability to sustain normal loudness growth and upper limit loudness tolerance may require occasional adjustment of maximum power output levels, as well as compression strategies in their hearing instruments.
Many of the newer digital (DSP) hearing aid circuits are ideally suited for such cases, especially with multiple programs that can be changed by the user when necessary to accommodate such variations. Diabetic users' thresholds also tend to fluctuate, especially as a result of auditory fatigue. Auditory fatigue is best described as diminishing threshold sensitivity over the course of the day. For that reason, it is suggested that diabetic hearing aid users be provided user volume controls (VC) with their hearing aids and, as an integral part of their rehabilitative training.
For those with more severe losses, training in the use of assistive listening and alerting devices, and effective coping and repair strategies can be crucial. Hence, the author subscribes to a holistic approach to auditory rehabilitation that virtually leaves no stone unturned in the search for achieving ''communicative wholeness''. This may necessitate working closely with other community professionals and consumer resources where possible.
BACK TO THE SHOES:
The patient referred to at the start of this article, like many others, was unaware of the connection between his three failed attempts at amplification and his chronic diabetic condition. Indeed, he was acutely aware of the diabetic's tendency to experience feet problems. Poor circulation and deterioration of the neurological apparatus (neuropathy) in the feet are common with diabetes mellitus. Therefore, he accommodated for that particular problem by purchasing the most comfortable and stylish running shoes on the market. Nothing but the best would do.
He also knew that he suffered from hearing loss, and sufferedpsychosocial limitations, as well. He took responsibility for his problem by "trying once more" (his words), hoping that somewhere, somehow, someone had the answer to his hearing problem.
The answer "somehow" turned out to be a appropriately fitted hearing instruments, this time taking into consideration his diabetic condition. Like his running shoes, "nothing but the best."
About the author...
Dr. Chartrand serves as Director of Research at DigiCare Hearing Research & Rehabilitation, is profoundly deaf and utilizes a cochlear implant. Correspondence: www.digicare.org.
(Portions of the above article have been excerpted and updated from: Chartrand, MS, "Diabetes and Hearing Health", Hearing Health, June/July, pp. 12, 1992.)
Brunt MA: Auditory Sequelea of Diabetes Mellitus (doctoral dissertation), University of Kansas, 1969.
Chartrand MS: Hearing Instrument Counseling: Practical Applications for Counseling the Hearing Impaired, second edition, Livonia, MI: National Institute for Hearing Instruments Studies, 1999.
Chartrand MS, Anton LJ: "Hearing Health Assessment and Case History," Advanced Audiometric Course, Gainesville, TX: Unimax Professional Education, 1991.
Chartrand, M.S. and Chartrand, G.A., ''Maximizing Your Hearing Dollars'', Hearing Health, fall issue, pp48-52 (2001).
Doyle ND. Hoffman JE: "General Medical Considerations in Audiology," Ch. 4, Handbook of Clinical Audiology, ed. Katz J, Baltimore, MD: Williams &Wilkins, 1981.
Durrant JD. Jean Lovrinic: Bases of Hearing Science, 2nd Ed., Baltimore, MD: Williams &Wilkins, 1984.
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Rintelmann WF, et al: Hearing Assessment, Austin, TX: Pro-ed, 1991.
Stach BA, Louiselle LH: Jerger JF: "Special Hearing Aid Considerations in Early Patients with Auditory Processing Disorders," Ear and Hearing, Vol. 12, No. 6, Supp., 1991.
Wafford MJ: "Hearing Disorder Management in Patients with Diabetes Mellitus," Hearing Journal, Vol. 42, No. 11, 1991.
Zelenka J. Kozak P: "Disorder in Blood Supply of the Inner Ear as Early Symptom of Diabetic Angiopathy," J Laryngol. Otol., 79, 1965.
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