Sudden Deafness on One Side - Is It Diabetes?

Summarized by Robert W. Griffith, MD
November 26, 2004

Introduction

Sudden loss of hearing can occur without obvious cause in older people. It's obviously distressing, especially if there's no clear reason for it. Sometimes atherosclerosis or viral infections are blamed. In fact, however, diabetes is probably a major cause. A Japanese study seems to confirm this. It's reported in the Diabetes Research and Clinical Practice journal, and we summarize it here.

What was done

The researchers collected data on 148 patients over 40 who were diagnosed with one-sided sudden loss of hearing. They were examined for the presence of type 2 diabetes, diabetic retinopathy (changes in the retina produced by diabetes), and kidney changes. Blood pressure and blood lipids were measured, smoking status recorded, and a careful history was taken to determine possible cardiovascular disease. Ultrasound examinations of the carotid artery were made to measure the thickness of the inner layer of the artery and to detect atherosclerotic plaques.

Hearing function tests included pure-tone audiometry from 125 to 8,000 Hertz, with mean hearing levels recorded from 250 to 4,000 Hertz. The tests were repeated after some weeks to detect possible recovery of hearing.

People with idiopathic (i.e. of unknown origin) sudden hearing loss were treated with corticosteroids, unless there was a risk of specific side effects of the drug (e.g. gastric ulcer, or an infection).

Analyses were done to establish a profile of diabetic patients with sudden hearing loss, and this was compared with non-diabetics with the same problem.

What was found

Out of the 148 patients with sudden hearing loss, there were 24 type 2 diabetics - roughly 16%. They were about the same age as the whole collective - average age 60. The following differences were seen in the diabetic patients, compared with the non-diabetics:

• High blood pressure was more common
• High cholesterol was more common
• Hearing in the affected ear was worse in the diabetics

There were no differences between the two groups with respect to the role played by age, vertigo, time since onset, and recovery rate (which was about 60%). However, when diabetic patients with sudden hearing loss were compared with diabetics without hearing loss, it was clear that the glycosylated hemoglobin levels (HbA1c) were significantly higher in those with deafness (7.8% vs. 7.2%).

Comment

This study shows that one-sided sudden hearing loss of unknown origin may, in fact, be due to diabetes. The likely mechanism is not directly related to changes suggestive of atherosclerosis, as the carotid artery lining thickness measurements were no different in the hearing-loss diabetics than in the non-diabetics. On the other hand, the increased HbA1c in the hearing-loss diabetics shows that the disease itself may be the responsible risk factor.

Whatever the mechanism, the message is fairly clear: if you suddenly go deaf in one ear, and there's no obvious cause for this, have your fasting blood sugar checked!

Source

• Idiopathic sudden hearing loss in patients with type 2 diabetes. M. Fukui, Y. Kitagawa, N. Nakamura,  et al., Diab Res Clin Pract, 2004, vol. 63, pp. 205--211

Related Links
Just How Common is Deafness in Older People?
Noise-Induced Hearing Loss
Hearing Loss

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