Metabolic disorders in vertigo, tinnitus, and hearing loss

Vertigo, tinnitus, and hearing loss are common complaints among populations of industrial countries, especially in persons older than 40 years. Numerous agents are known to incite vertigo, tinnitus, and hearing loss, among them hyperinsulinemia, diabetes mellitus, and hyperlipidemia. In this study, we proposed to assess the occurrence of hyperinsulinemia, diabetes mellitus, and hyperlipidemia in patients suffering from vertigo, tinnitus, or hearing loss of unknown origin. Results of various tests in 48 patients were compared to those in 31 control subjects. Assessments of body mass index, blood pressure, and laryngological, audiometric, and electronystagmographic parameters were performed in all study participants. An oral glucose tolerance test was used to evaluate insulin levels, and lipoprotein phenotyping served to determine cholesterol, triglyceride, and lipoprotein levels. Patients were found to be significantly more overweight (on the basis of body mass index) than were the control subjects. Hypertension was more common among patients than controls, but the difference was significant only between the men in the two groups. Disturbances of glucose metabolism were found in 27.1% of patients but in only 9.7% of controls. Diabetes mellitus was not present in any controls but was identified in four patients. Hyperinsulinemia was almost twice as common in patients as in controls. Only the occurrence of hyperlipoproteinemia seemed not to differ between patients and control subjects. We conclude that such disturbances of glucose metabolism as diabetes mellitus and hyperinsulinemia may be responsible for inner ear diseases, whereas the role of disturbances of lipid metabolism remains vague.