Hearing Loss Risk Over 4 Times Higher in People With Type 2 Diabetes: Meta-Analysis
Spain: A new systematic review and meta-analysis has shed light on a frequently overlooked complication of type 2 diabetes mellitus (T2D): hearing loss.
Published in Otolaryngology–Head and Neck Surgery, the review was conducted by Miguel Caballero-Borrego, MD, PhD, and Ivan Andujar-Lara, MD, from the Hospital Clinic and Universitat de Barcelona, Spain. Their findings indicate a strong and consistent association between T2D and deteriorating auditory function.
Although the link between diabetes and vision impairment is well established, the authors highlighted that hearing loss may similarly stem from subtle microvascular damage. They explained that chronic hyperglycemia can cause structural alterations in small blood vessels, including those supplying the inner ear. These microcirculatory changes may thicken the basilar membrane, damage the ultrastructure of cochlear capillaries, and cause atrophy of the stria vascularis—mechanisms that can gradually impair hearing.
Given this biological plausibility, the authors suggested that hearing loss could serve as an early warning sign of underlying microangiopathy in diabetic individuals, warranting closer surveillance and tailored management strategies.
The review was prompted by inconsistencies in earlier clinical studies examining this association. To address these gaps, the researchers conducted a PRISMA-guided search of PubMed and Scopus for studies published between January 2019 and April 2024. Of 8,354 articles initially identified, 17 studies met the eligibility criteria, encompassing 3,910 individuals with diabetes and 4,084 controls. Data extraction, quality assessment, and pooled analyses were performed using robust tools, including the Newcastle-Ottawa Scale and Cochrane Review Manager.
The study reported the following findings:
- The prevalence of hearing loss among individuals with type 2 diabetes ranged from 40.6% to 71.9%, significantly higher than in non-diabetic groups.
- Pooled data showed that people with T2D had over a fourfold increased risk of hearing impairment (OR 4.19).
- Pure-tone audiometric thresholds were consistently worse in diabetic individuals, averaging 3.19 dB higher than controls, indicating reduced auditory sensitivity.
- High-frequency hearing loss was more pronounced, with a mean difference of 2.3 dB compared to controls, while low-frequency impairment was milder.
- Higher HbA1c levels correlated with more severe hearing deficits, highlighting the role of glycemic control.
- Longer duration of diabetes significantly increased risk; those with more than 10 years of diabetes had over twice the likelihood of developing hearing loss.
- Sex did not appear to influence the prevalence or severity of hearing impairment.
The authors noted that heterogeneity across study populations and the lack of cardiovascular risk profiling may limit interpretation, as cardiovascular disease itself can contribute to auditory decline.
The investigators emphasize that hearing loss may reflect early microvascular injury in T2D. Any new or worsening hearing difficulties, especially when accompanied by other microvascular complications, should prompt clinicians to reassess diabetes management to slow further auditory decline.
Reference:
Type 2 Diabetes Mellitus and Hearing Loss: A Prisma Systematic Review and Meta‐Analysis. Otolaryngology--Head and Neck Surgery, 173(5), 1041. https://doi.org/10.1002/ohn.1346
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