Sex-specific associations between diabetes mellitus and hearing loss in the middle-aged and elderly: a national cohort study of Chinese adults

Associations between diabetes mellitus and sensorineural hearing loss from humans and animal studies

There is controversy regarding the association and etiopathogenesis of diabetes mellitus (DM) and sensorineural hearing loss (SNHL). Some studies support that SNHL develops because of angiopathy and/or neuropathy caused by DM, but many of the findings have been inconsistent. This review aims to highlight a select number of studies that effectively describe the relationship between DM and SNHL, thus bringing more attention and awareness to this area of research. This review also describes animal models to understand better the mechanisms of DM contributing to SNHL in the inner ear. The goal of this narrative review is for researchers and healthcare professionals to further their understanding and investigation of the etiopathogenesis of both DM and SNHL, therefore leading to the development of effective treatments for diabetic patients displaying symptoms of SNHL.

Polygenic Risk Score Modifies the Association of HbA1c With Hearing Loss in Middle-Aged and Older Chinese Individuals: The Dongfeng-Tongji Cohort

OBJECTIVE

Evidence regarding the modifying effect of the polygenic risk score (PRS) on the associations between glycemic traits and hearing loss (HL) was lacking. We aimed to examine whether these associations can be influenced by genetic susceptibility.

RESEARCH DESIGN AND METHODS

This cross-sectional study included 13,275 participants aged 64.9 years from the Dongfeng-Tongji cohort. HL was defined according to a pure tone average >25 dB in the better ear and further classified by severity. Prediabetes and type 2 diabetes (T2D) were defined based on the 2013 criteria from the American Diabetes Association. A PRS was derived from 37 single nucleotide polymorphisms associated with HL. Multivariable logistic regression models were fitted to estimate the associations of PRS and glycemic traits with HL and its severity.

RESULTS

Elevated fasting plasma glucose (FPG), glycosylated hemoglobin (HbA1c), and T2D were positively associated with higher HL risks and its severity, with odds ratios (ORs) ranging from 1.04 (95% CI 1.00, 1.08) to 1.25 (95% CI 1.06, 1.46). We also found significant interaction between HbA1c and PRS on risks of overall HL and its severity (P for multiplicative interaction <0.05), and the effects of HbA1c on HL risks were significant only in the group with high PRS. Additionally, compared with normoglycemia in the group with low PRS, T2D was associated with an OR of up to 2.00 and 2.40 for overall HL and moderate to severe HL, respectively, in the group with high PRS (P for additive interaction <0.05).

CONCLUSIONS

PRS modifies the association of HbA1c with HL prevalence among middle-aged and older Chinese individuals.

Diabetes mellitus and hearing loss

Diabetes mellitus (DM) is a major disease threatening human health and its incidence is increasing year on year. As a chronic complication of DM, hearing loss mostly occurs undetectably. However, the mechanism of this diabetes-related hearing loss (DRHL) remains unclear and there is no effective clinical treatment. Studies of animal or human pathology show that DM causes damage to the blood vessels, spiral ganglion neurons, afferent nerve fibers, the organ of Corti, and the stria vascularis of the inner ear. In recent years, more advances in pathological research have revealed the possible mechanism of DRHL. In addition, a large number of clinical studies suggest that the duration and severity of DM are closely related to the incidence and severity of DRHL. This review focuses on the relationship between DM and hearing loss. The clinical audiological characteristics of diabetic patients, risk factors for DRHL, typical pathology, and potential interventions of DRHL are summarized. This will help reveal the pathogenesis and intervention approaches for DRHL.