Type 2 diabetes and hearing loss in personnel of the Self-Defense Forces

The association of type 2 diabetes with hearing loss was evaluated in middle-aged male personnel of the Self-Defense Forces (SDFs). Hearing loss was defined as the pure-tone average (PTA) of the thresholds frequency at 0.5, 1, 2, and 4 kHz greater than 25 dB hearing levels (HL) in the worse ear. Diabetes status was determined by self-report of physician-diagnosed diabetes or by oral glucose tolerance test (OGTT). Of 699 subjects studied (age 52.9 ± 1.0 years), 103 subjects were classified as having type 2 diabetes. Fasting plasma glucose of diabetic subjects was 120 ± 19 mg/dl. Hearing loss levels were (worse) higher among diabetic subjects compared with subjects with normal glucose tolerance (NGT) (30.7 ± 13.0 dB versus 27.4 ± 12.3 dB, P = 0.014). Hearing loss was more prevalent among diabetic subjects than among subjects with normal glucose tolerance (60.2% versus 45.2%, P = 0.006). The odds ratio (OR) of type 2 diabetes for the presence of hearing loss was 1.87 (95% confidence interval 1.20–2.91, P = 0.006) in a logistic regression analysis adjusted for age, rank, cigarette smoking and ethanol consumption. These results suggest that type 2 diabetes is associated with hearing loss independently of lifestyle factors in middle-aged men.