There is a strong correlation between diabetes and hearing loss, affirms Dr G Krishnakumar
Diabetics are counselled to take care of their feet and consult an eye specialist once a year at least. However, the link between diabetes and hearing loss was overlooked by the medical fraternity until recently.
Are people with diabetes at a higher risk of hearing loss than those whose blood sugar levels are normal? According to a recent study published in the US, diabetics are about twice as likely to suffer hearing loss as they get older. Therefore, one needs to undergo hearing tests on a regular annual basis. The study is one of the many that have continued to come out to establish the role of diabetes in the development of hearing loss. But the relationship between diabetes and hearing loss was not fully studied and supported. Most of the information that came out was inconclusive and obscure. The ear in particular was a difficult area to study, and this may have contributed to the gaps in knowledge.
For one, the ears are affected by a number of factors such as advancing age, heredity, noise, medicines, and viruses, aside from diabetes. Any one of these could cause hearing loss. Isolating a single factor is a tricky task but improvements in research techniques have managed to overcome this problem.
Furthermore, the actual hearing organ, the cochlea, cannot be examined directly. The cochlea, which is the part of the inner ear that converts sound energy to nerve impulses, is very small and protected by a hard bone. Even with special equipment, this organ is hard to reach. The structures inside are delicate and can be easily damaged. Because of the risk of inducing hearing loss themselves, researchers have often used animals to understand the function of the human ear and learn how it is affected by disease.
The studies that do involve human subjects are actually post-mortem investigations — autopsies of a deceased person’s ears. Individuals who donate their bodies to science after death were hard to come by before. To get one body which had both hearing loss and diabetes was even harder. Without the appropriate tools to conduct a study, research lagged for years and the link was not established.
But in 2005, a group of researchers published several articles in the journal, Otolaryngology-Head and Neck Surgery, that were able to establish this connection. Using post-mortem ears as subjects, the researchers found that the ears of individuals who had Type 1 or Type 2 diabetes showed severe damage in their cochlea. They also observed that the damage to the cochlea shared the same characteristic pathology as the other diabetic complications. Their conclusion that hearing loss was a likely result of the diabetes provided one of the stronger evidences for this suspicion in years.
More studies were to come in support of this link. Data gathered at the Department of Veterans Affairs National Center for Rehabilitative Auditory Research in Oregon, USA, confirmed that not only was hearing loss more likely to be found in diabetic patients, hearing loss was also present in younger patients. This finding was echoed by another study, which was a survey done in a community to detect hearing loss from various causes. Not only did the researchers find cases of hearing loss among diabetic residents, they discovered the problem to be present in all age groups.
But they were particularly concerned that some of the people affected were actually unaware of their hearing loss, despite having poor hearing test results.
Another study that came out showed that diabetics may be prone to having wax build up in their ears than most people. This is because a substance called keratin, which helps clear the ear of wax, is said to be absent or decreased in diabetics. The result is wax that builds up quickly in the canal and in a short time leads to blockage. This prevents sound from reaching the eardrum, and produces a type of hearing loss called air conduction deafness.
Because of the many studies that have been conducted so far, there is a move now among specialists in India to implement a programme that would institutionalise routine ear care and hearing loss prevention among diabetics. They share the view of many researchers that hearing loss can be prevented or minimised in the early stages. Such programmes should reach the same prominence and recognition as the programmes that prevent blindness, heart disease and diabetic foot problems. In the near future, an annual hearing test would become a routine step in diabetic management similar to an annual eye check up.
Because no such drive exists for now, it is important for diabetics to work closely with their physicians. If you believe you have a hearing problem, you should not ignore it. Some of the early signs may include hearing hissing noise or buzzing in the ears, constantly asking people to repeat themselves, needing to sit closer in class to hear the teacher, and people noticing that you watch TV or listen to the radio at a very loud decibel level.
Remember, prevention is better than cure. Hearing loss is preventable. And people generally sacrifice up to seven years of good hearing because they do not acknowledge their hearing loss. Seven years of easy conversation, clear sounds, better living and socialisation are lost. Get your hearing tested today.
(The author is an audiologist and clinic director of Rajan Speech and Hearing.)
