Hearing loss common in diabetics

Hearing loss is nearly twice as common among diabetic adults than their healthy counterparts, according to a new study. Researchers stumbled on the phenomenon after analysing the results of tests administered to a nationally representative sample in the US.

The test measured their ability to hear low, middle, and high frequency sounds in both ears. The link between diabetes and hearing loss became evident across all frequencies, with a stronger association in the high frequency range.

Adults with pre-diabetes, whose blood glucose is higher than normal but not high enough for a diabetes diagnosis, had a 30 percent higher rate of hearing loss compared to those with normal blood sugar tested after an overnight fast.

The researchers analysed data from hearing tests administered between 1999 and 2004 under the National Health and Nutrition Examination Survey (NHANES), held by the Centres for Disease Control and Prevention (CDCP).

Half of the 11,405 surveyed, aged between 20 to 69 were randomly assigned to have their hearing tested, and nearly 90 percent of them completed the hearing exam and the diabetes questionnaire.

"Hearing loss may be an under-recognised complication of diabetes," said co-author Catherine Cowie of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).

Diabetes may lead to hearing loss by damaging the nerves and blood vessels of the inner ear, the researchers suggested, a finding also supported by autopsies of such patients.

Diabetes is a group of diseases marked by high levels of blood glucose resulting from defects in insulin production, insulin action, or both.

Afflicting nearly 21 million people in US, it is a major cause of heart disease and stroke and the most common cause of blindness, kidney failure and lower limb amputations in adults.

Pre-diabetes, which causes no symptoms, affects about 54 million adults in the US, many of whom will develop type 2-diabetes in the next 10 years.

These findings were published online on Tuesday in the Annals of Internal Medicine.