The study showed that women aged between 60 and 75 years, whose diabetes was controlled appropriately, were able to hear better with similar hearing levels to non-diabetic women of the same age, compared with those who had poorly controlled diabetes. The findings also demonstrated substantially worse hearing levels in all diabetic women below the age of 60 years, even when their diabetes is controlled appropriately.
In contrast, the study showed that all men, irrespective of age, and whether or not they were diabetic, displayed worse hearing loss compared with women.
Derek J. Handzo, D.O., of the Department of Otolaryngology-Head & Neck Surgery at Henry Ford explained:
"A certain degree of hearing loss is a normal part of the aging process for all of us, but it is often accelerated in patients with diabetes, especially if blood-glucose levels are not being controlled with medication and diet. Our study really points to importance of patients controlling their diabetes, especially as they age, based on the impact it may have on hearing loss."The American Diabetes Association estimates that almost 26 million individuals in the U.S. are diabetic, with another 34.5 million suffering some degree of hearing loss, including difficulty hearing background noises or conversations in large groups, and regularly needing to turn up the volume on TV or radio.
Despite earlier investigations into the association between diabetes and hearing loss, the Henry Ford researchers decided to explore hearing differences amongst patients with well-controlled diabetes, those with poorly controlled diabetes, and healthy controls with no diabetes.
They reviewed records for 990 patients who received audiograms between 2000 and 2008 at the hospital, and categorized patients by whether they were diabetic, gender and age, i.e. below the age of 60 years, between 60 and 75 years and above the age of 75 years. The researchers used the guidelines of the American Diabetes Association, which uses HbA1C blood levels to split the diabetics into two groups, those with well - or poorly controlled diabetes.
According to Dr. Handzo, earlier studies on diabetes and hearing loss did not focus on blood-glucose levels or include such a diverse population based on age and gender.
The team examined the patients' pure tone average, a measurement that establishes the hearing level at certain frequency, and speech recognition at different ages, before evaluating pure tone average ranges, which concentrate on the frequency at which most people talk, as well as very high frequencies used in music and alarms.
The findings showed that the hearing of women with poorly controlled diabetes aged between 60 and 75 years was substantially worse when compared with those whose diabetes was well controlled and the control group. Diabetic women below the age of 60 years, regardless of whether or not the diabetes was well controlled or not, had worse hearing than non-diabetic women.
The researchers observed no substantial hearing difference amongst any men in the study in all groups, i.e. in those with well - or poorly controlled diabetes, or those with no diabetes.
Dr. Handzo comments:
"Younger males in general have worse hearing, enough so to possibly mask any impact diabetes may have on hearing. But our findings really call for future research to determine the possible role gender plays in hearing loss."