Patients with type 2 diabetes mellitus had a 4.19-fold increased risk of hearing loss compared with controls, according to a systematic review and meta-analysis published in Otolaryngology–Head and Neck Surgery.
The analysis of 17 studies from January 2019 to April 2024, encompassing 3,910 patients with diabetes and 4,084 controls, found hearing loss prevalence ranging from 41% to 72% among diabetic cohorts.
Pure-tone audiometry revealed mean thresholds 3 dB higher in patients with diabetes compared with controls. High-frequency hearing (4,000-8,000 Hz) demonstrated a 2.3 dB elevation, significantly exceeding the 1.1 dB difference observed at low frequencies (500-1,000-2,000 Hz).
Disease duration emerged as a critical variable. Patients with diabetes duration exceeding 10 years were twice as likely to experience hearing loss compared with those with shorter disease duration, with zero heterogeneity across studies.
Glycemic control correlated with hearing loss severity. Patients with moderate hearing loss exhibited hemoglobin A1c (HbA1c) levels 0.6% higher than controls, while those with severe-to-profound hearing loss showed levels elevated by nearly 1%. Mild hearing loss showed no significant HbA1c association.
Gender demonstrated no significant influence on hearing loss prevalence, based on analysis of 2,712 male and 3,364 female patients with diabetes.
The researchers noted that persistent hyperglycemia damages microvascular and macrovascular structures, with the cochlea indirectly affected through microcirculatory alterations. These changes include basilar membrane thickening and stria vascularis atrophy, potentially explaining preferential high-frequency loss.
Study limitations included language restrictions (English and Spanish only), heterogeneity in cohort characteristics, and inability to establish causality due to unknown pre-diabetes hearing status. The researchers emphasized that most identified hearing loss remained within mild ranges, complicating clinical significance assessment.
"Hearing loss in DM may be a consequence of subclinical microvascular disease. This fact could potentially serve as an early warning sign, suggesting that closer monitoring is necessary, as well as the adaptation of treatment plans to minimize the occurrence or progression of hearing loss," the researchers concluded.
The authors declared having no competing interests.
