title: Glycosylated hemoglobin level is associated with hearing impairment in older Japanese: the Kurabuchi Study.
abstract: OBJECTIVE
  To examine the association between glycemic levels (glycosylated hemoglobin (HbA1c)) and hearing impairment in a general older population.
  
  
  METHODS
  Community-based prospective longitudinal cohort study.
  
  
  METHODS
  Kurabuchi Town, Gunma Prefecture, Japan.
  
  
  METHODS
  Residents (N = 831; 350 men, 481 women) aged 65 and older were examined in 2005 and 2006 and analyzed in a cross-sectional study. Residents without hearing impairment at baseline who participated in audiometric re-examinations 4 years later were analyzed (n = 338).
  
  
  METHODS
  Hearing impairment was defined as failure to hear a 30-dB signal at 1 kHz and a 40-dB signal at 4 kHz in the better ear in pure-tone audiometric tests.
  
  
  RESULTS
  Mean HbA1c level (National Glycohemoglobin Standardization Program) was 5.8 ± 0.8% (40 mmol/mol). Odds ratios (ORs) and 95% confidence intervals (CIs) of hearing impairment associated with HbA1c were estimated using a logistic regression model. In the cross-sectional analysis, HbA1c levels were positively associated with hearing impairment (OR per 1.0% increase in HbA1c = 1.30, 95% CI = 1.00-1.68). This association persisted even after excluding 58 participants with a self-reported history of diagnosed diabetes mellitus. Longitudinal analysis revealed the temporality of the discussed association (OR = 1.52, 95% CI = 1.03-2.23).
  
  
  CONCLUSIONS
  The present study provides supportive evidence for a causal link between hyperglycemia and age-related hearing loss.
authors.forename: Takehiro
authors.initials: T
authors.lastname: Michikawa
authors.forename: Kunio
authors.initials: K
authors.lastname: Mizutari
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Saito
authors.forename: Toru
authors.initials: T
authors.lastname: Takebayashi
authors.forename: Yuji
authors.initials: Y
authors.lastname: Nishiwaki
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People; D003430:Cross-Sectional Studies; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis*; D034381:Hearing Loss / Q000097:blood*; D006801:Humans; D008297:Male; D011446:Prospective Studies
chemical_list: D006442:Glycated Hemoglobin