Objectives: This study was performed to determine whether there is an association between impaired fasting glucose and noise-induced hearing loss. Methods: The study subjects were workers in one automobile manufacturing company. The data were obtained from results of health examinations during 2005 and 2009. The factors analyzed were age, smoking and alcohol history, work duration, environmental noise level, hearing thresholds, blood pressure, serum creatinine, initial hearing threshold and fasting glucose. Results: The hearing thresholds at 4,000 Hz frequencies for both ears were significantly higher in 2009 than those in 2005. The changes in the hearing thresholds of the subjects with an impaired fasting glucose (100-125 mg/dl) and diabetes (≥126 mg/dl) were greater than those of the normal (<100 mg/dl) group. After adjusting for variables such as age, smoking and alcohol history, environmental noise, hypertension and serum creatinine, fasting glucose was found to be a significant variable. Impaired fasting glucose (100-125 mg/dl) was significant (β=1.339, p=0.002) for the right ear, whereas it was not significant (β=0.639, p=0.121) for the left ear. Conclusions: Impaired fasting glucose, as well as diabetes, might be risk factors for hearing loss in individuals with exposure to certain noise levels. The results of this study suggest that impaired fasting glucose should be considered a risk factor for hearing loss.
2011 by the Japan Society for Occupational Health