Diabetes mellitus and the incidence of hearing loss: a cohort study

Abstract

Background: To evaluate the association between diabetes mellitus (DM) and the development of incident hearing loss.

Methods: Prospective cohort study was performed in 253 301 adults with normal hearing tests who participated in a regular health-screening exam between 2002 and 2014. The main exposure was the presence of DM at baseline, defined as a fasting serum glucose ≥ 126 mg/dL, a self-reported history of DM or current use of anti-diabetic medications. Pre-diabetes was defined as a fasting glucose 100-125 mg/dL and no history of DM or anti-diabetic medication use. Incident hearing loss was defined as a pure-tone average of thresholds at 0.5, 1.0 and 2.0 kHz > 25 dB in both right and left ears.

Results: During 1 285 704 person-years of follow-up (median follow-up of four years), 2817 participants developed incident hearing loss. The rate of hearing loss in participants with normal glucose levels, pre-diabetes and DM were 1.8, 3.1 and 9.2 per 1000 person-years, respectively ( P < 0.001). The multivariable-adjusted hazard ratios for incident hearing loss for participants with pre-diabetes and DM compared with those with normal glucose levels were 1.04 (95% confidence interval 0.95-1.14) and 1.36 (1.19-1.56), respectively. In spline regression analyses, the risk of incident hearing loss increased progressively with HbA1c levels above 5%.

Conclusions: In this large cohort study of young and middle-aged men and women, DM was associated with the development of bilateral hearing loss. DM patients have a moderately increased risk of future hearing loss.

Keywords: cohort study; diabetes mellitus; hearing loss; incidence; risk factors.

Figure 1.

Flow chart of study design.

Figure 2.

Cumulative incidence of incident hearing loss by baseline diabetes status.

Figure 3.

Hazard ratios for incident hearing loss by levels of baseline HbA1c. Curves represent adjusted hazard ratio (solid line) and its 95% confidence interval (dashed lines) based on restricted cubic spline for HbA1c with knots at the 5th, 35th, 65th and 95th percentiles of its sample distribution. The reference value (diamond dot) was set at the 10th percentile of the distribution (corresponding to HbA1c = 5.1%). Model was adjusted for age spline, sex, study centre, year of visit, exposure to occupational noise, body mass index, smoking, alcohol, vigorous exercise, total and HDL cholesterol, triglycerides and hypertension. Bars represent the frequency distribution of HbA1c.

Figure 4.

Associations between baseline diabetes status and hearing loss in pre-specified subgroups. Diabetes status was defined based on fasting glucose levels, history of diabetes and use of anti-diabetic medications. Models were adjusted for age spline, sex, study centre, year of visit, exposure to occupational noise, body mass index, smoking, alcohol, vigorous exercise, total and HDL cholesterol, triglycerides and hypertension.