Hearing Loss and Deafness
Hearing loss is a very common condition that usually develops gradually with age or as a result of repeated exposure to loud noise.
There are a number of other factors which can cause loss of hearing, including illness and physical trauma. Some researchers believe the presence of diabetes could contribute to hearing loss or deafness.
In fact, hearing loss has been shown to be twice as common in adults with diabetes compared to those without the disease.
What is hearing loss?
The terms hearing loss, hearing impairment and deafness refers to a partial or total inability to hear.
Cases of impaired hearing are usually categorised by their type, their severity (mild, moderate, severe, or profound deafness are the 4 different levels of hearing loss), and the age of onset (before or after a person can recognise and understand language).
How common is hearing loss?
In the UK, approximately 1 in 6 people, or 10 million Britons, suffer from a partial or total inability to hear.
What causes hearing loss?
Hearing loss develops when sound signals are unable to reach the brain.
This can be due to:
- Damage to the auditory nerve - the sensitive hair cells inside the cochlea (part of the inner ear), which transmit the impulses from the cochlea to the hearing centre in the brain. This is an age-related and permanent form of hearing loss known as sensorineural hearing loss.
- Blockages or build-up of fluid - earwax, ear infections, a perforated ear drum or damage to the hearing bones can all prevent sounds from passing from your outer ear to your inner ear. This is known as conductive hearing impairment, and is often a temporary problem.
In some cases, both of these problems can occur and/or combine to cause what is known as mixed hearing loss.
Factors that can lead to sensorineural, conductive, or mixed hearing loss, in addition to aging, include:
- Prolonged exposure to loud noises or sounds - noise is the cause of roughly half of all cases of hearing loss and responsible for some degree of hearing problems in 5% of the global population
- Genes - hearing loss can be inherited
- Illness - measles, meningitis and mumps can all lead to some degree of hearing loss, as well as neurological disorders such as multiple sclerosis and stroke
- Medicines - antibiotics, anti-inflammatory drugs and diuretics can cause irreversible ear damage, which is why their use is limited
- Physical trauma - people who sustain head injury are especially vulnerable to hearing loss or tinnitus, either temporary or permanent
- Chemicals - combined with noise, certain chemicals can have increase a person’s hearing loss
Is diabetes a risk factor for deafness?
Diabetes has been linked to the development of hearing problems in various research studies.
Health experts medical researchers have debated the possible link between diabetes and hearing loss since the 1960s and early attempts to establish such as association were not very convincing. But in recent years there has been growing evidence to suggest diabetes contributes to hearing loss.
In June 2008, a study by the U.S. National Institutes of Health (NIH) published in the Annals of Internal Medicine, found a strong and consistent link between impaired hearing and diabetes.
After analysing the results of hearing tests given to a nationally representative sample of working-age adults in America, the investigators found participants with diabetes or pre-diabetes were more likely to have at least mild hearing loss in their ability to hear low-to-mid and high-frequency tones compared to people without diabetes.
The results remained the same after accounting for major factors known to affect hearing, such as age, noise exposure, income level, and the use of certain medications.
In July 2011, researchers from the Tsukuba University Hospital Mito Medical Center in Ibaraki, Japan, found that hearing loss is more than twice as common in people with diabetes than in non-diabetics.
The team studied the results of 13 studies involving nearly 8,800 people with hearing impairment and 23,839 people without impaired hearing. Of those with hearing problems, they found more than 1,000 had diabetes, compared to just under 2,500 of those with normal hearing, indicating that diabetic patients are 2.3 times more likely to suffer from mild hearing loss.
How does diabetes cause hearing loss?
While it unknown exactly why hearing loss is more common among people with diabetes, autopsy studies of diabetes patients suggest this association is caused by neuropathy (nerve damage), which is a common complication of both type 1 and type 2 diabetes.
Researchers believe prolonged high blood glucose levels may lead to hearing loss by affecting the supply of blood or oxygen to the tiny nerves and blood vessels of the inner ear. Over time, the nerves and blood vessels become damaged, affecting the person's ability to hear.
Maternally Inherited Diabetes and Deafness
Hearing loss can be a maternally inherited problem for some people with diabetes. In fact, 1% of all diabetes patients are diagnosed with a subtype of the disease known as Maternally Inherited Diabetes and Deafness (MIDD), and of these 75% experience sensorineural hearing loss.
MIDD is a non insulin-dependent type of diabetes that usually develops before the age of 40 years as a result of a mutation in mitochondrial DNA.
What are the signs of hearing loss?
Hearing loss can be so gradual that you may not notice it. You may have impaired hearing if you:
- Find it hard hearing other people clearly?
- Regularly ask people to repeat themselves
- Are accused of not listening to people when you are
- Listen to music or watch TV with a high volume
- Find it difficult hearing the telephone, your mobile, an alarm clock or the door bell
Being aware of these early signs of hearing loss is important for identifying problems quickly and at an early stage where treatment can be a lot more effective.
When should I see my doctor?
You should make an appointment to see your GP and have your hearing checked if you:
- Notice any of the signs of hearing loss highlighted above
- Experience sudden hearing loss in one or both ears
- Have severe earache or signs of an ear infection
How is it diagnosed?
If you are having problems with your hearing, the first thing your doctor will do is exam your ears to look for anything abnormal.
If further tests are required to determine what is causing your hearing loss, your GP may refer you to an audiologist (a hearing specialist) or an ear, nose and throat (ENT) surgeon who will also be able to determine the severity of the hearing impairment and recommend the best course of treatment.
Coping with hearing loss
There a number of different ways to help improve hearing loss.
The form of treatment recommended to you will depend on the cause and severity of your loss of hearing, but the aim of each option is the same - to improve your ability to hear and communicate.
Sensorineural hearing loss treatment
There are several treatment options for this type of permanent hearing loss, including:
- Digital hearing aids - electronic devices that improve hearing by raising the volume of sounds entering your ear. There are various different types of hearing aids available, either through the NHS or privately.
- Cochlear implants - small implantable hearing devices that sit inside the inner ear (under the skin). They are designed for people whose loss of hearing is not helped by hearing aids.
- Auditory brainstem implants - surgically-implanted device that is only used in some cases of severe hearing loss, where the hearing nerve is not functioning properly.
- Lip reading or sign language - forms of communication for people with profound hearing loss, where speech and ability to understand others is also affected.
Conductive hearing loss treatment
Treatment for conductive hearing loss ranges from medication and minor surgery to major surgery in cases where perforated eardrums or hearing bones need to be repaired.
Hearing aids may also be recommended as part of treatment.
If you're hearing loss is found to be the result of neuropathy, then treatment will focus on closely lowering your blood glucose levels and keeping them within the normal range, as well as maintaining a healthy diet and regular exercise.