A population-based study of the association between dysglycaemia and hearing loss in middle age

GRP78 protein metabolism in obese and diabetic rats: a study of its role in metabolic disorders

OBJECTIVE

This study aimed to compare and analyze the expression and significance of the GRP78 protein in cochlear cell injury induced by a high glucose and high-fat diet in obese and diabetic rats.

METHODS

Male SD rats were randomly divided into two groups: normal (NC) and high-fat (HF) groups. The NC group was fed a standard diet for eight weeks, while the HF group received a high-glucose, high-fat diet. The HF group was further categorized into the obesity group (OB group) and the type II diabetes mellitus group (T2DM group). To induce a type II diabetes mellitus (T2DM) model, the T2DM group received an intraperitoneal injection of a small dose of STZ (45 mg/kg). After four weeks on the original diet, body weight, blood glucose, blood lipid levels, and auditory brainstem response (ABR) thresholds were measured. The cochlea was dissected, and its morphology was observed using HE staining. Immunohistochemistry and western blotting were utilized to examine the expression level of the GRP78 protein in the cochlea.

RESULTS

(1) The ABR threshold demonstrated a statistically significant difference between the T2DM group and the OB group (P < 0.05), as well as between the OB group and the NC group (P < 0.05). (2) Based on morphological comparisons from HE-stained sections, the T2DM group exhibited the most significant alterations in the number of cells in the spiral ganglion, the organ of Corti, and the stria vascularis of the cochlea. (3) The expression level of the GRP78 protein in the cochlea was higher in the T2DM group compared to the OB group (P < 0.05) and higher in the OB group compared to the NC group (P < 0.05).

CONCLUSION

The findings indicate that the GRP78 protein plays a role in hearing loss caused by T2DM and hyperlipidemia. Moreover, T2DM is more likely than hyperlipidemia to be associated with hearing impairment.

Associations between medical conditions and auditory dysfunction in US Veterans

OBJECTIVE

To examine associations between non-otologic medical conditions and auditory dysfunction.

DESIGN

Cross-sectional analysis of baseline data from the Noise Outcomes in Service members Epidemiology (NOISE) study. Logistic regression was used to estimate the association between medical conditions (0, 1, and 2 or more conditions) and auditory dysfunction (hearing loss pure tone average ≥20 dB HL and tinnitus), adjusting for key confounders including noise exposure. Secondarily, the association between specific medical conditions and auditory dysfunction was examined. All variables were self-reported.

STUDY SAMPLE

United States military Veterans (n = 580) with mean age 34.1 years (standard deviation = 9.2), who were within approximately 2.5 years of separation from service.

RESULTS

Compared to Veterans reporting no medical conditions, Veterans reporting two or more had increased odds on low-frequency hearing loss and on tinnitus but not on high or extended-high frequency hearing loss. Furthermore, specific conditions sleep disorder and arthritis were associated with auditory dysfunction.

CONCLUSIONS

Non-otologic medical conditions were associated with low-frequency hearing loss and tinnitus in this sample of young Veterans. This suggests medical conditions may play a role in Veterans' hearing health. Whether management of medical conditions earlier in life reduces the risk of hearing loss and tinnitus requires further study.

The influence of metabolic syndrome on age-related hearing loss from the perspective of mitochondrial dysfunction

With the increase in life expectancy in the global population, aging societies have emerged in many countries, including China. As a common sensory defect in the elderly population, the prevalence of age-related hearing loss and its influence on society are increasing yearly. Metabolic syndrome is currently one of the main health problems in the world. Many studies have demonstrated that metabolic syndrome and its components are correlated with a variety of age-related diseases of the peripheral sensory system, including age-related hearing loss. Both age-related hearing loss and metabolic syndrome are high-prevalence chronic diseases, and many people suffer from both at the same time. In recent years, more and more studies have found that mitochondrial dysfunction occurs in both metabolic syndrome and age-related hearing loss. Therefore, to better understand the impact of metabolic syndrome on age-related hearing loss from the perspective of mitochondrial dysfunction, we reviewed the literature related to the relationship between age-related hearing loss and metabolic syndrome and their components to discern the possible role of mitochondria in both conditions.

The impact of cardiovascular diseases on hearing deterioration: a 13-year follow-up study

OBJECTIVE

To study the impact of cardiovascular diseases (CVDs) on hearing deterioration among ageing adults in a longitudinal setting. Furthermore, to describe the pure tone threshold changes at the 0.125-8 kHz frequency range over 13 years.

DESIGN

A population-based follow-up study.

STUDY SAMPLE

A random sample of 850 adults, of whom 559 participated in the follow-up study. Otological examination, a structured interview, and pure tone audiometry were conducted. Multivariate regression models were used to estimate the effect of CVD (participants had at least one cardiovascular condition) on hearing deterioration of the better ear hearing level (BEHL), defined as a change in the pure-tone average (PTA) of the frequencies 0.5, 1, 2, and 4 kHz and separately at the lower (0.125, 0.25, and 0.5 kHz) and higher (4, 6, and 8 kHz) frequencies.

RESULTS

In the multivariable-adjusted analysis, the BEHL change at 13 years was 0.7 dB greater among participants with CVD (p = 0.3). The mean BEHL change during the 13-year follow-up was 12.0 dB (95% CI 11.4-12.6) among all participants.

CONCLUSIONS

No significant association between CVD and hearing threshold changes was found.

Quantitative criteria for age-related hearing loss using audiometric configuration analysis

OBJECTIVES

To suggest the most adaptable criteria of age-related hearing loss (ARHL) using prevalence matching with population-based data.

METHODS

We chose 30, 25, 20, and 15 dB as gap ranges of cutoff values of the descending type of hearing loss, between an average of low (500 Hz, 1 kHz) and high (4 kHz, 6 kHz) frequencies. Interaural difference was defined as 10 or 15 dB. Hearing loss was defined over 25 dB. We compared the prevalence results of the cross-matching criteria. We used population-based data from the Korea National Health and Nutrition Examination Survey. We assumed that the prevalence of ARHL ranged from 25 to 35%, and this prevalence will increase gradually with age.

RESULTS

Among the eight possible criteria, age ≥ 65 years, average of all frequencies > 25 dB at the each sides, gap between low- and high frequencies ≥ 20 dB, and interaural difference ≤ 10 dB were the most suitable criteria to suggest a quantitative definition of ARHL audiometrically.

CONCLUSION

In the current study, we recommend the new, quantitative ARHL criteria. The suggested criteria for ARHL might be easily accessed by other researchers to demonstrate their own hypotheses.

The effect of diabetes on 4-year changes of hearing thresholds in male workers exposed to noise in a single company: a longitudinal study

Background

Recently, several studies have assessed the association between diabetes and hearing impairment. However, the effect of diabetes on hearing impairment is not well known in diabetic patients exposed to noise, a typical cause of hearing impairment. The aim of this study is to longitudinally analyze the effect of diabetes on hearing impairment in workers exposed to similar noise levels from 2013 to 2017 who had experienced little change in their working conditions.

Methods

The study subjects included 2,087 male workers exposed to noise in a single company and who underwent health examinations at the same hospital in Ulsan city in 2013 and 2017. Hearing impairment was defined that a pure-tone average of pure-tone audiometry (PTA) thresholds at 1,000, 2,000, 3,000, and 4,000 Hz was 25 dB and over in both ears. Statistical analyses were conducted using χ² tests, ANOVA, and Cox proportional hazard models. We analyzed covariates that might affect hearing impairment, including age; working period; levels of total cholesterol, triglyceride, and serum creatinine; smoking and alcohol history; and noise level.

Results

The average PTA thresholds and their average changes between 2013 and 2017 were significant in the diabetes mellitus (DM) group than those in the normal and impaired fasting glucose group. Among the subjects with the same status of fasting glucose group in 2013 and 2017, the adjusted hazard ratios for incident hearing impairment among those in the DM group compared to normal group were 3.35 (95% confidence interval [CI], 1.54–7.29) in the left ear and 5.66 (95% CI, 2.01–15.98) in the right ear.

Conclusions

This study suggested that the risk of hearing impairment in the DM group was significantly higher than that in the normal group in both ears, even when exposed to similar noise levels.

Hearing threshold levels and hearing loss among people in Zhejiang, China: a population-based cross-sectional study

Hearing loss (≥26 dB threshold in the better ear), as a common chronic condition in humans, is increasingly gaining attention. Relevant research in China is relatively scarce, so we conduct a population-based study to investigate the prevalence of hearing loss among age groups, genders and ears in Zhejiang province, China, from September 2016 to June 2018.

STUDY DESIGN

Population-based cross-sectional study PARTICIPANTS: A total of 3754 participants aged 18-98 years and living in Zhejiang province, China.

OUTCOME MEASURES

Pure-tone audiometric thresholds were measured at frequencies of 0.125-8 kHz for each subject. All participants were asked to complete a structured questionnaire, in the presence of a healthcare official.

RESULTS

The prevalence of speech-frequency and high-frequency hearing loss was 27.9% and 42.9%, respectively, in Zhejiang. There were significant differences in auditory thresholds at most frequencies among the age groups, genders (male vs female: 31.6%vs24.1% at speech frequency; 48.9% vs 36.8% at high frequency) and ears. In addition to the common factors affecting both types of hearing loss, a significant correlation was found between personal income and speech-frequency hearing loss (OR=0.69, 95% CI 0.52 to 0.92), and between hyperlipidaemia and high-frequency hearing loss (OR=1.45, 95% CI 1.02 to 2.07).

CONCLUSION

The prevalence of hearing loss was high among people living in Zhejiang, particularly males, and in the left ear. Moreover, hearing thresholds increased with age. Several lifestyle and environment factors, which can be influenced by awareness and education, were significantly associated with hearing loss.

Self-reported hearing loss in Russians: the population-based Ural Eye and Medical Study

OBJECTIVE

With data on frequency of hearing loss in Russia and Eastern Europe generally lacking, we assessed the prevalence of hearing loss in a Russian population.

SETTING

The population-based Ural Eye and Medical Study was conducted in the rural and urban regions of Bashkortostan, Russia.

PARTICIPANTS

With an inclusion criterion of age 40+ years, the study included 5899 (80.5%) out of 7328 eligible individuals (mean age: 59.0±10.7 years; range: 40-94 years).

PRIMARY AND SECONDARY OUTCOME MEASURES

Hearing loss was examined in 5397 (91.5%) study participants, assessed using a standardised interview with questions from the 'Hearing Handicap Inventory for the Elderly Screening Version (HHIE-S)'.

RESULTS

The prevalence of self-reported hearing loss (26.1%, 95% CI 24.2 to 27.2) increased from 10.9% (95% CI 8.0 to 13.7) in participants aged 40-45 years old to 59.0% (95% CI 51.6 to 66.4) in those aged 80+ years old. It was higher for men than for women in the 60-80 years age group (38.93%, 95% CI 35.8 to 42.1, vs 32.8%, 95% CI 30.2 to 35.3; p=0.003). On multivariable analysis, higher prevalence of hearing loss was associated with older age (p<0.001; OR [per year of age]: 1.06 [1.06 to 1.07]), male gender (p<0.001; OR: 1.26 [1.09 to 1.47]), higher depression score (p<0.001; OR: 1.06 [1.04 to 1.08]), higher prevalence of headache (p=0.001; OR: 1.27 [1.10 to 1.47]), history of cardiovascular diseases including stroke (p=0.001; OR: 1.32 [1.13 to 1.55]), and osteoarthritis (p<0.001; OR: 1.40 [1.18 to 1.67]), physically vigorous activity during work (p<0.001; OR: 1.40 [1.21 to 1.62]), alcohol consumption (p<0.001; OR: 1.51 [1.28 to 1.78]), and dry eye feeling (p<0.001; OR: 1.67 [1.30 to 2.16]). It was marginally correlated with a higher anxiety score (p=0.07; OR: 1.03 [0.998 to 1.06]). It was independent of diabetes (p=0.52), arterial hypertension (p=0.20), level of education (p=0.11), region of habitation (p=0.70), blood concentration of high-density lipoproteins (p=0.17) and low-density lipoproteins (p=0.52), current smoking (p=0.95) and smoking pack-years (p=0.37), and best corrected visual acuity (p=0.93).

CONCLUSIONS

As in other countries the prevalence of hearing loss is high in this elderly population in Russia. It is primarily or secondarily associated with older age, depression, male gender, cardiovascular disease and alcohol consumption.

Alteration of auditory function in type 2 diabetic and pre-diabetic patients

BACKGROUND

The association between type 2 diabetes mellitus (T2DM) and hearing loss has not been fully investigated and there is little information on the effects of pre-diabetes on alterations in auditory function in Chinese subjects.

METHODS

The study recruited 51 patients with T2DM, 55 patients with pre-diabetes and 43 control subjects. Auditory function was assessed by pure tone audiometry (PTA) tests and distortion product of otoacoustic emissions (DPOAEs). Tinnitus symptoms were recorded using a medical history questionnaire.

RESULTS

A significantly larger number of patients with T2DM (45.1%) were affected by hearing loss, compared to pre-diabetes patients (23.6%; p = .04) and control subjects (25.6%; p = .02), as assessed by PTA. There was no significant difference in PTA between the number of pre-diabetes patients and control subjects. In contrast, mean DPOAEs amplitudes of the pre-diabetes patients were significantly lower than of the control subjects, at all frequencies investigated, except 0.75 kHz. A significantly greater number of pre-diabetes patients reported tinnitus symptoms.

CONCLUSIONS

Diabetes is associated with bilateral sensorineural hearing loss, especially at high frequencies. While pre-diabetes is not necessarily associated with significant hearing loss, there may be cochlear malfunction, as indicated by DPOAEs. Thus, patients with pre-diabetes who have tinnitus may benefit from DPOAEs and PTA tests.