Diabetes mellitus as etiological factor of hearing loss

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.

The construction and validation of prognostic prediction model for sudden sensorineural hearing loss in middle-aged and elderly people

OBJECTIVE

Idiopathic sudden sensorineural hearing loss (ISSNHL), as an otologic emergency, is commonly encountered and its prevalence has been climbing every year recently. To our knowledge, the prognosis of middle-aged and elderly patients is worse than that of young patients. Previous researches mainly focused on the adult population, which was considered as prognostic models who performed hearing recovery in ISSNHL. However, few studies regarding the middle-aged and elderly population who are regarded as prognostic models have been reported. Therefore, we aim to construct and validate a nomogram-based prognostic prediction model, which can provide a reference for the prognostic assessment in the middle-aged and elderly patients with ISSNHL.

METHOD

A total of 371 middle-aged and elderly ISSNHL patients who were admitted to the Department of Otolaryngology-Head and Neck Surgery, Yanbian Hospital, Yanbian University, from April 2018 to April 2023 were enrolled in the study. All subjects were randomly divided into two groups including training group (n = 263) and validation group (n = 108). Lasso regression and multi-factor logistic regression were jointly utilized to screen out prognosis-related independent risk factors and establish a nomogram-based risk prediction model. The accuracy and clinical application value of the model were evaluated by combining the Bootstrapping method and k-fold cross-validation, plotting the receiver operating characteristic  (ROC)  curve, calculating the area under the ROC curve (AUC), plotting the decision curve analysis (DCA), and the calibrating curve.

RESULT

We used the method of lasso regression combined with multivariate logistic regression and finally screened out eight predictors (including age, number of affected ears, degree of hearing loss, type of hearing curve, duration of disease, presence of vertigo, diabetes, and lacunar cerebral infarction) that were included into the nomogram. The C-index were 0.823 [95% CI (0.725, 0.921)] and 0.851 [95% CI (0.701, 1.000)], and the AUC values were 0.812 and 0.823 for the training and validation groups, respectively. The calibration curve for the validation group was approximately conformed to that for the modeling group, indicating favorable model calibration. The DCA results revealed the modeling group (3%-86%) and the validation group (2%-92%) showed significant net clinical benefit under the majority of thresholds.

CONCLUSION

This study developed and validated a nomogram-based prognostic prediction model which based on the eight independent risk factors mentioned above. The predictors are conveniently accessible and may assist clinicians in formulating individualized treatment strategies.

Evaluation of the auditory brainstem response test in patients with type 2 diabetes mellitus

Background

Hearing loss is an unknown complication of diabetes mellitus (DM). The aim of this study was to evaluate hearing function using auditory brainstem response (ABR) in diabetic patients.

Methods

The present case-control study was performed on thirty diabetic patients as a case group and thirty healthy individuals as a control group. Baseline demographic information, HbA1c level, and duration of diabetes were obtained from all diabetic patients. In all subjects, the ABR and pure-tone audiometry (PTA) tests were performed and the results were analyzed using the t-test and logistic regression.

Results

The absolute latency of I was significantly lower in diabetes patients. The absolute latency of III and the interpeak latencies (IPL) I-III were significantly higher in diabetic patients. No significant relationship was noticed in the absolute latency of V and the IPL I-V among diabetic patients in the right and left ears (P>0.05).

Conclusion

The results of this study suggested that diabetes may cause central auditory dysfunction manifested on the absolute latency of III, the IPL I-III and III-V.

Association of different severity of diabetic retinopathy and hearing loss in type 2 diabetes mellitus

PURPOSE

Microvascular involvement in patients with diabetes mellitus is one of the causes of retinopathy, nephropathy, and neuropathy. The same pathologic processes may occur in the inner ear structures. This case-control study aimed to evaluate the hearing thresholds in type 2 diabetic patients with different severity of diabetic retinopathy (DR) and to compare these findings with controls.

MATERIALS AND METHODS

We evaluated the hearing threshold in four groups of eligible subjects aged 20-70 years. These groups were controls, diabetic patients with no-DR, with mild-moderate non-proliferative DR (NPDR), and with severe NPDR/proliferative DR (PDR). Each group consisted of 105 subjects. Speech-frequency and high-frequency hearing levels (SFHL and HFHL, respectively) were measured and log-transformed. Analysis of covariance was used. The prevalence rate of moderate or more hearing loss in the groups was estimated.

RESULTS

In total, 194 men and 226 women participated. The ratio of means of SFHL and HFHL between PDR and controls was 0.18 and 0.20, respectively. Hearing loss was prevalent in severe NPDR/PDR (adjusted prevalence ratio 3.36 for SFHL and 1.51 for HFHL) compared to controls. Also, the prevalence of high-frequency hearing loss was more in mild-moderate NPDR (adjusted prevalence ratio 1.33).

CONCLUSIONS

The magnitude of the increase in hearing impairment prevalence between the severe NPDR/PDR patients and controls was about 24% for both SFHL and HFHL. We recommend hearing assessment in the screening of the DR patients.

An unbiased algorithm for objective separation of Alzheimer's, Alzheimer's mixed with cerebrovascular symptomology, and healthy controls from one another using electrovestibulography (EVestG)

Diagnosis of Alzheimer's disease (AD) from AD with cerebrovascular disease pathology (AD-CVD) is a rising challenge. Using electrovestibulography (EVestG) measured signals, we develop an automated feature extraction and selection algorithm for an unbiased identification of AD and AD-CVD from healthy controls as well as their separation from each other. EVestG signals of 24 healthy controls, 16 individuals with AD, and 13 with AD-CVD were analyzed within two separate groupings: One-versus-One and One-versus-All. A multistage feature selection process was conducted over the training dataset using linear support vector machine (SVM) classification with 10-fold cross-validation, k nearest neighbors/averaging imputation, and exhaustive search. The most frequently selected features that achieved highest classification performance were selected. 10-fold cross-validation was applied via a linear SVM classification on the entire dataset. Multivariate analysis was run to test the between population differences while controlling for the covariates. Classification accuracies of ≥ 80% and 78% were achieved for the One-versus-All classification approach and AD versus AD-CVD separation, respectively. The results also held true after controlling for the effect of covariates. AD/AD-CVD participants showed smaller/larger EVestG averaged field potential signals compared to healthy controls and AD-CVD/AD participants. These characteristics are in line with our previous study results.

Association between Statin Use and Sensorineural Hearing Loss in Type 2 Diabetic Patients: A Hospital-Based Study

Statins have emerged as protective agents against sensorineural hearing loss (SNHL) associated with dyslipidemia, but the effects of statins on SNHL are not consistent. The purpose of this study was to investigate the association between statin use and the risk of SNHL using a hospital cohort. This nested case-control study included type 2 diabetic patients over the age of 18 years without a history of hearing loss. Of these, 1379 patients newly diagnosed with SNHL or tinnitus were classified as cases, and 5512 patients matched to the cases based on age, sex, and index year were classified as controls. Chi-squared tests were used to compare categorical variables between the two groups. Odds ratios (ORs) and adjusted odds ratios (AOR) were calculated from univariate and multivariable unconditional logistic regression analyses, respectively. There was a significant difference in the prevalence of statin use between the cases and controls (53.7% vs. 61.2%, respectively; p < 0.001). The use of statins in type 2 diabetic patients significantly reduced the risk of SNHL or tinnitus by 24.8% (95% CI 14.2–34.1%, p < 0.001) after controlling for confounders. Similar results were found for the association between statin use and SNHL (AOR = 0.706; 95% CI 0.616–0.811, p < 0.001). The protective effects of statins against SNHL were consistent regardless of age and sex. The use of statins for type 2 diabetic patients was significantly associated with a reduced risk of SNHL, regardless of age and sex. Further studies are needed, especially large cohort studies, to evaluate the long-term protective effects of statins.

Auditory and Vestibular Functioning in Individuals with Type-2 Diabetes Mellitus: A Systematic Review

Introduction  Diabetes mellitus is a metabolic disease associated with a rise in the level of blood glucose. Individuals with diabetes mellitus are more likely to develop hearing loss, tinnitus, and dizziness due to macro- and microvascular complications. The extent to which auditory and vestibular functions are impaired in individuals with type-2 diabetes mellitus is still under debate.

Objective  To systematically review studies focusing on auditory and vestibular functions in individuals with type-2 diabetes mellitus.

Data Synthesis  A search was conducted in the PubMed, MedlinePlus, Ingenta Connect and Google Scholar databases for articles published until June 2019. A total of 15,980 articles were primarily retrieved, 33 of which were shortlisted based on the inclusion criteria set by the investigators for the systematic review. Out of 33 full-length articles, 26 evaluated the functioning of the auditory system, while 7 evaluated the functioning of the vestibular system. Most studies related to auditory functioning reported a significant effect of type-2 diabetes mellitus on the peripheral auditory system, whereas studies on vestibular functioning reported no significant effect of diabetes mellitus on the functioning of the peripheral vestibular end-organ.

Conclusion  Overall, the results of various audiological and peripheral vestibular tests reveal distinctive peripheral and/or central auditory and vestibular end-organ impairments in individuals with type-2 diabetes mellitus.

Clinical Features and Hearing Outcomes of Sudden Sensorineural Hearing Loss in Diabetic Patients

Background and Objectives

This study aimed to evaluate the clinical features and the clinical factors associated with prognosis of sudden sensorineural hearing loss (SSNHL) in diabetic patients.

Subjects and Methods

Forty-nine diabetic with unilateral SSNHL were retrospectively included. All patients received systemic high dose steroid therapy within one month after onset and had more than one month of follow-up audiogram. The basic characteristics of the patients, initial and follow-up audiograms, laboratory data, and methods of steroid treatment were collected.

Results

Compared to reference values in healthy subjects, 79%, 55%, and 45% of the patients had higher values of mean neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR), and lymphocyte-monocyte ratio (LMR), respectively. Older patients had significantly less degree of hearing loss, but they also had significantly worse hearing thresholds in the unaffected ear. After steroid treatment, less than half patients (47%) showed hearing recovery. Simultaneous intratympanic dexamethasone (ITD) injections with systemic steroid did not confer an additional hearing gain or an earlier recovery rate in diabetic patients with SSNHL. In the multivariate analysis, initial hearing thresholds of affected ear and timing of steroid treatment were significantly associated with hearing prognosis in diabetic patients with SSNHL.

Conclusions

Diabetic patients with SSNHL tended to have increased NLR, LMR, and PLR, which are reported to be associated with microvascular angiopathy. Simultaneous ITD injections to improve hearing recovery in diabetic patients with SSNHL seems unnecessary.

An Investigation of Hearing (250-20,000 Hz) in Children with Endocrine Diseases and Evaluation of Tinnitus and Vertigo Symptoms

Introduction  Despite much advancement in medicine, endocrine and metabolic diseases remain an important cause of morbidity and even mortality in children.

Objective  The present study was planned to investigate the evaluation of hearing that also includes high frequencies, and the presence and degree of vertigo and tinnitus symptoms in pediatric patients diagnosed with endocrine diseases such as type 1 diabetes mellitus (DM), growth hormone deficiency (GHD), obesity, idiopathic short stature, and precocious puberty

Methods  The present study included a patient group of 207 children patients diagnosed with endocrine disease (95 males, 112 females; mean age 9.71 years old [range 6–16 years old]) and a control group including 55 healthy children who do not have any kind of chronic disease (26 males, 29 females; mean age 9.33 years old [range 6–16 years old]). The subjects underwent a hearing test with frequencies between 250 and 20,000 Hz. The vestibular and tinnitus symptoms were evaluated with the Pediatric Vestibular Symptom Questionnaire.

Results  Out of 207 patients in the patient group, 5 (2.4%) had hearing loss in pure tones, 10 (4.8%) had it in high frequencies, 40 (19.3%) had tinnitus symptoms, and 18 (8.7%) had vertigo symptoms. A total of 4 out of 207 patients in the study group (1.9%), 2 out of 59 with type 1 DM patients (3.4%), 1 out of 46 with GHD (2.2%), and 1 out of 43 obesity patients (2.3%) had hearing loss, vertigo, and tinnitus symptoms.

Conclusions  Our results suggest that some childhood endocrine diseases can cause some changes in the inner ear, although the exact cause is unknown. Perhaps, a detailed hearing and balance examination should be a routine in a child diagnosed with an endocrine disease. We think it is necessary to work on more comprehensive patient groups and tests in the future.

Relationship between Inflammatory Food Consumption and Age-Related Hearing Loss in a Prospective Observational Cohort: Results from the Salus in Apulia Study

Age related hearing loss (ARHL) affects about one third of the elderly population. It is suggested that the senescence of the hair cells could be modulated by inflammation. Thus, intake of anti- and pro-inflammatory foods is of high interest.

METHODS

From the MICOL study population, 734 participants were selected that participated in the 2013 to 2018 examination including hearing ability and from which past data collected in 2005/2008 was available. ARHL status was determined and compared cross-sectionally and retrospectively according to clinical and lifestyle data including food and micronutrient intake.

RESULTS

ARHL status was associated with higher age but not with education, smoking, relative weight (BMI), and clinical-chemical blood markers in the crossectional and retrospective analyses. Higher intake of fruit juices among ARHL-participants was seen cross-sectionally, and of sugary foods, high-caloric drinks, beer, and spirits retrospectively. No difference was found for the other 26 food groups and for dietary micronutrients with the exception of past vitamin A, which was higher among normal hearing subjects.

CONCLUSIONS

Pro-inflammatory foods with a high-sugar content and also beer and spirits were found to be assocated with positive ARHL-status, but not anti-inflammatory foods. Diet could be a candidate for lifestyle advice for the prevention of ARHL.

Association Between Type 2 Diabetes Mellitus and Hearing Loss Among Patients in a Coastal City of South India

Diabetes mellitus (DM) is a metabolic culprit known to perpetuate several disease processes. The relationship between hearing loss (HL) and type 2 DM (T2DM) remains unclear despite the vast volume of research devoted to this topic. We conducted this study with the aim to evaluate HL among T2DM patients and to assess the relationship between severity of HL, glycosylated hemoglobin (HbA1c) levels and duration of T2DM.

DESIGN

a time bound descriptive crosssectional study.

SETTING

tertiary care hospital of South India.

SUBJECTS

subjects with T2DM, aged from 40 to 60 years (excluding hypertension, chronic noise exposure and history of smoking or ototoxicity) were included.

METHODS

Non-random convenience sampling. Details were gathered using a self-administered, semistructured questionnaire and the hearing was assessed by pure tone audiometry. Data was analysed using SPSS. A large proportion of the sampled population had audiological assessments suggestive of SensoriNeural HL (SNHL). 90.2% had a bilateral distribution of HL; however, only 39% of patients reported having any associated ear complaints. No statistically significant associations were obtained between severity of HL, glycaemic control, duration of diabetes or gender. Bilateral SNHL is a complication associated with T2DM. Duration and glycaemic control are independent variables and do not statistically influence the severity of HL. However, this study demonstrated that many patients with SNHL had no symptoms and also lacked awareness of HL in DM. Therefore routine assessment of hearing should be considered in the diabetic population.

Auditory and Vestibular Side Effects of FDA-Approved Drugs for Diabetes

As of September 10, 2019, there were 75 medications (oral/injectable/inhalants) approved by the U.S. Food and Drug Administration for diabetes management: 1 inhalant, 21 oral combinations, 22 injectable, and 31 oral medications (not in combination with any other diabetes drug). This article isolates the auditory and vestibular side effects of those drugs as reported by the drug's manufacturer as well as those side effects that could interfere with a balance assessment. Twenty of the 75 approved medications (26%) could have an auditory-related side effect. Hearing loss and tinnitus are not on the list. Only two, or just 3%, have vertigo and spinning as reported side effects (one each). More than 50% of the drugs will have some effect on a balance assessment. Audiologists who evaluate a patient with diabetes (PWD) are presented with symptoms that could be related to their diabetes medication. Although the manufacturer might report a side effect as rare or as a percentage from their clinical trials subjects, not all PWD will experience these adverse events. Auditory and vestibular side effects do not dominate the diabetes drug side effect list, but, rather, the most reported side effects could impact a balance assessment. The lists that appear in Appendices A and B should serve as a guide for all professionals involved in managing the PWD (i.e., audiologists, otolaryngologists, diabetes educators, pharmacists, optometrists, dentists, etc.). The list also serves as a counseling tool if a communication problem emerges during the progression of the diabetes.

NADPH Oxidase 2-Mediated Insult in the Auditory Cortex of Zucker Diabetic Fatty Rats

Clinical data has confirmed that auditory impairment may be a secondary symptom of type 2 diabetes mellitus (T2DM). However, mechanisms underlying pathologic changes that occur in the auditory system, especially in the central auditory system (CAS), remain poorly understood. In this study, Zucker diabetic fatty (ZDF) rats were used as a T2DM rat model to observe ultrastructural alterations in the auditory cortex and investigate possible mechanisms underlying CAS damage in T2DM. The auditory brainstem response (ABR) of ZDF rats was found to be markedly elevated in low (8 kHz) and high (32 kHz) frequencies. Protein expression of NADPH oxidase 2 (NOX2) and its matching subunits P22^phox, P47^phox, and P67^phox was increased in the auditory cortex of ZDF rats. Expression of 8-hydroxy-2-deoxyguanosine (8-OHdG), a marker of DNA oxidative damage, was also increased in the neuronal mitochondria of the auditory cortex of ZDF rats. Additionally, decreases in the mitochondrial total antioxidant capabilities (T-AOC), adenosine triphosphate (ATP) production, and mitochondrial membrane potential (MMP) were detected in the auditory cortex of ZDF rats, suggesting mitochondrial dysfunction. Transmission electron microscopy results indicated that ultrastructural damage had occurred to neurovascular units and mitochondria in the auditory cortex of ZDF rats. Furthermore, cytochrome c (Cyt c) translocation from mitochondria to cytoplasm and caspase 3-dependent apoptosis were also detected in the auditory cortex of ZDF rats. Consequently, the study demonstrated that T2DM may cause morphological damage to the CAS and that NOX2-associated mitochondrial oxidative damage and apoptosis may be partly responsible for this insult.

Decreased Protein Kinase C Expression in the Cochlear Fibroblasts of Diabetic Rat Models Induced by Curcumin

OBJECTIVES

Microcirculation and hemodynamic disturbances, including in the cochlea, are commonly found in diabetic patients. A study on diabetic rats discovered histopathological changes in outer hair cells and the spiral ganglion and mitochondrial damage in the ear. Hyperglycemia can increase the activation of protein kinase C (PKC). Curcumin as an antioxidant also affects the regulation of PKC and Ca2+. The aim of this study was to determine the role of curcumin in decreasing PKC expression in the cochlear fibroblasts of diabetic rats.

MATERIALS AND METHODS

An experimental study was performed on 24 Wistar rats divided into the following 6 groups: group 1: control group; group 2: diabetic group without curcumin administration; groups 3 and 4: diabetic groups with curcumin administration (200 mg/kg and 400 mg/kg for 3 days, respectively); groups 5 and 6: diabetic groups with curcumin administration (200 mg/kg and 400 mg/kg for 8 days, respectively). Cochlear tissues were taken from all groups and immunohistochemistry-stained, and the PKC expression scores were analyzed with one-way ANOVA (a significance level of 0.05).

RESULTS

Significant differences in PKC expression (p<0.05) were found between group 1 and group 2, and group 2 and groups 3, 4, 5, and 6. There was no significant difference in PKC expression regarding the different doses and the duration of curcumin administration.

CONCLUSION

Curcumin can reduce PKC expression in the cochlear fibroblasts of diabetic rats.

Auditory Late Latency Response in Individuals with Type 2 Diabetes Mellitus

OBJECTIVES

The study was done to compare Auditory late latency response (ALLR) in normal-hearing individuals without diabetes mellitus and normal-hearing individuals with type 2 diabetes mellitus (T2DM).

MATERIALS AND METHODS

A total of 50 participants within the age range of 40-60 years were enrolled in the study based on the inclusion and exclusion criteria. They were divided into two groups with one group consisting of 25 individuals with T2DM and the other group consisted of 25 individuals without diabetes as the control group.

RESULTS

The results revealed prolonged latencies and reduced amplitude of P1, N1 and P2 wave among individuals with T2DM compared to control group. There was a significant positive correlation observed for ALLR latency and duration of T2DM, and a negative correlation observed for ALLR amplitude and duration of T2DM.

CONCLUSION

The present study concluded that there is a problem in the encoding of speech at the cortical level despite normal hearing in individuals with type 2 diabetes mellitus.

Effects of diabetes mellitus and systemic arterial hypertension on elderly patients' hearing

INTRODUCTION

Chronic diseases can act as an accelerating factor in the auditory system degeneration. Studies on the association between presbycusis and diabetes mellitus and systemic arterial hypertension have shown controversial conclusions.

OBJECTIVE

To compare the initial audiometry (A1) with a subsequent audiometry (A2) performed after a 3 to 4-year interval in a population of elderly patients with diabetes mellitus and/or systemic arterial hypertension, to verify whether hearing loss in these groups is more accelerated when compared to controls without these clinical conditions.

METHODS

100 elderly individuals participated in this study. For the auditory threshold assessment, a previous complete audiological evaluation (A1) and a new audiological evaluation (A2) performed 3-4 years after the first one was utilized. The participants were divided into four groups: 20 individuals in the diabetes mellitus group, 20 individuals in the systemic arterial hypertension group, 20 individuals in the diabetes mellitus/systemic arterial hypertension group and 40 individuals in the control group, matching them with each study group, according to age and gender. ANOVA and Kruskal-Wallis statistical tests were used, with a significance level set at 0.05.

RESULTS

When comparing the mean annual increase in the auditory thresholds of the A1 with the A2 assessment, considering each study group and its respective control, it can be observed that there was no statistically significant difference for any of the frequencies for the diabetes mellitus group; for the systemic arterial hypertension group, significant differences were observed after 4kHz. For the diabetes mellitus and systemic arterial hypertension group, significant differences were observed at the frequencies of 500, 2kHz, 3kHz and 8kHz.

CONCLUSION

It was observed that the systemic arterial hypertension group showed the greatest decrease in auditory thresholds in the studied segment when compared to the other groups, suggesting that among the three studied conditions, hypertension seems to have the greatest influence on hearing.

Etiology of Noise-Induced Hearing Loss (NIHL) and its Symptomatic Correlation with Audiometry Observations in Type II Diabetes

Type II diabetic mellitus (DM) is a chronic metabolic disease that impairs normal insulin production and glucose transport to the liver and muscles. In the India, about 1-5% population suffer from diabetes or related complication. So there is need to cure this disease. DM chronic auditory complications may include spiral ganglia atrophy, degeneration of the vestibulocochlear nerve myelin sheath, reduction of the number of spiral lamina nerve fibres, and thickening of the capillary walls of the stria vascularis and small arteries. This study aims to know the incidence of common parameters, blood sugar levels, levels of lipids and the hearing thresholds of individuals. It is a Noise-Induced Hearing Loss research study featuring hearing impairment in transport workers diagnosed as type II diabetic. All individuals were interviewed by various questioners related to listening ability of subjects and underwent a physical examination, blood investigations and audiometry. Hearing impairment was more prevalent among adults with diabetes. Sensory neuron hearing loss is predominant in both study groups. Mixed Bilateral Hearing Loss showed significant p value in (>.001) by audiometry. The percentage of hearing loss in diabetes (ranges 5.3-28.1%) and in non-diabetics (ranges 3.4-24.1%) and risk factors in diabetes (ranges 22.8-35.1%) over nondiabetics (ranges 17.2-20.1%) which is eye opener. The correlation between type II diabetes and hearing impairment was independent of known risk factors for hearing impairment, such as noise exposure, build-up wax, ototoxic medication, smoking, tobacco chewing etc.

Speech perception performance of subjects with type I diabetes mellitus in noise

INTRODUCTION

Diabetes mellitus (DM) is a chronic metabolic disorder of various origins that occurs when the pancreas fails to produce insulin in sufficient quantities or when the organism fails to respond to this hormone in an efficient manner.

OBJECTIVE

To evaluate the speech recognition in subjects with type I diabetes mellitus (DMI) in quiet and in competitive noise.

METHODS

It was a descriptive, observational and cross-section study. We included 40 participants of both genders aged 18-30 years, divided into a control group (CG) of 20 healthy subjects with no complaints or auditory changes, paired for age and gender with the study group, consisting of 20 subjects with a diagnosis of DMI. First, we applied basic audiological evaluations (pure tone audiometry, speech audiometry and immittance audiometry) for all subjects; after these evaluations, we applied Sentence Recognition Threshold in Quiet (SRTQ) and Sentence Recognition Threshold in Noise (SRTN) in free field, using the List of Sentences in Portuguese test.

RESULTS

All subjects showed normal bilateral pure tone threshold, compatible speech audiometry and "A" tympanometry curve. Group comparison revealed a statistically significant difference for SRTQ (p=0.0001), SRTN (p<0.0001) and the signal-to-noise ratio (p<0.0001).

CONCLUSION

The performance of DMI subjects in SRTQ and SRTN was worse compared to the subjects without diabetes.

Effects of obesity on protein kinase C, brain creatine kinase, transcription, and autophagy in cochlea

Diet-induced obesity (DIO) has been shown to exacerbate hearing degeneration via increased hypoxia, inflammatory responses, and cell loss via both caspase-dependent and caspase-independent apoptosis signaling pathways. This study aimed to investigate the effects of DIO on the mRNA expressions of protein kinase c-β (PKC-β), brain creatine kinase (CKB), transcription modification genes, and autophagy-related genes in the cochlea of CD/1 mice. Sixteen 4-week-old male CD/1 mice were randomly divided into 2 groups. For 16 weeks, the DIO group was fed a high fat diet (60% kcal fat) and the controls were fed a standard diet. Morphometry, biochemistry, auditory brainstem response thresholds, omental fat, and histopathology of the cochlea were compared. Results showed that body weight, body length, body-mass index, omental fat, plasma triglyceride, and auditory brainstem response thresholds were significantly elevated in the DIO group compared with those of the control group. The ratio of vessel wall thickness to radius in the stria vascularis was significantly higher in the DIO group. The cell densities in the spiral ganglion, but not in the spiral prominence, of the cochlea were significantly lower in the DIO group. The expression of histone deacetylation gene 1 (HDAC1) was significantly higher in the DIO group than the control group. However, the expressions of PKC-β, CKB, HDAC3, histone acetyltransferase gene (P300), lysosome-associated membrane protein 2 (Lamp2), and light chain 3 (Lc3) genes were not significantly different between two groups. These results suggest that DIO might exacerbate hearing degeneration possibly via increased HDAC1 gene expression in the cochlea of CD/1 mice.

Relationships Among Factors Relevant to Abdominal Fat and Age-Related Hearing Loss

Objectives

Metabolic syndrome is related with abdominal fat and with age-related hearing loss (ARHL). In this study, we evaluated the association between a variety of factors relevant to abdominal fat (FRAs) and hearing thresholds.

Methods

We reviewed retrospectively the medical records of 2,602 subjects aged over 40 years with symmetrical sensorineural hearing loss who underwent abdominal fat computed tomography (CT) scans. Univariate and multivariate linear regression analyses were used to demonstrate the association between each FRA and hearing thresholds at low and high frequencies.

Results

Four of 5 FRAs were associated with hearing thresholds at high frequencies in males. All FRAs examined showed a relationship with hearing thresholds at low frequencies in females. Diabetes mellitus (DM) among clinical factors and visceral adipose tissue (VAT) among the 5 FRAs were the most reflective of hearing thresholds in both males and females.

Conclusion

We found that FRAs were associated with hearing loss with frequency specific characteristics according to sex and reinforced that DM and VAT is particularly an important role for hearing.

A Study on Effects of Diabetes Mellitus on Auditory System

Background and aims: Auditory dysfunctions in diabetes are known but are difficult to identify. Role of clinical tests and routine audiological tools are still to be established in early detection of diabetes-related auditory complication. The study aims to establish a link between diabetes and auditory dysfunction and assess the role of clinical examination and audiological investigations as a sensitive indicator of auditory dysfunctions in diabetics.

Material and Methods: The auditory functions of 100 diabetic patients and 100 non-diabetics were assessed by clinical otological examination including free-field hearing and pure tone audiometry (PTA) in this descriptive study. The data for diabetic and non-diabetic groups and effect of age on auditory functions were analyzed with suitable statistical tests using SPSS 2.0 software with an error margin of 10%.

Results: The demographical variables were comparable in both groups. The results showed a decline in free field hearing, which are furthur adversely affected by duration of diabetes and patient’s age. Overall pure tone thresholds were not significantly higher in diabetics, however the thresholds were higher in diabetics in older age groups. The hearing loss appears at an early age in diabetics but gradually becomes indistinguishable from age-related hearing loss.

Conclusions: The auditory dysfunction can be linked to diabetes. It is usually not detectable at earliest stages with routine clinical and audiological tests but the clinical tests and pure tone audiometry can have a utility in monitoring the auditory dysfunction.

Retrospective data suggests that the higher prevalence of benign paroxysmal positional vertigo in individuals with type 2 diabetes is mediated by hypertension

OBJECTIVE

Benign Paroxysmal Positional Vertigo (BPPV) has been linked to comorbidities like diabetes and hypertension. However, the relationship between type 2 diabetes (DM) and BPPV is unclear. The purpose of this retrospective study was to examine the relationship between DM and BPPV in the presence of known contributors like age, gender and hypertension.

METHODS

A retrospective review of the records of 3933 individuals was categorized by the specific vestibular diagnosis and for the presence of type 2 DM and hypertension. As the prevalence of BPPV was higher in people with type 2 DM compared to those without DM, multivariable logistic regressions were used to identify variables predictive of BPPV. The relationship between type 2 DM, hypertension and BPPV was analyzed using mediation analysis.

RESULTS

BPPV was seen in 46% of individuals with type 2 DM, compared to 37% of individuals without DM (p< 0.001). Forty two percent of the association between type 2 DM and BPPV was mediated by hypertension, and supported hypertension as a complete mediator in the relationship between type 2 DM and BPPV.

CONCLUSIONS

Hypertension may provide the mediating pathway by which diabetes affects the vestibular system. Individuals with complaints of dizziness, with comorbidities including hypertension and diabetes, may benefit from a screening for BPPV.

Evaluation of Audiometric Test Results to Determine Hearing Impairment in Patients with Rheumatoid Arthritis: Analysis of Data from the Korean National Health and Nutrition Examination Survey

This study aimed to evaluate the association between rheumatoid arthritis (RA) and hearing impairment in the Korean adult population. Audiometric and laboratory test data from the 2010–2012 Korean National Health and Nutrition Examination Survey (KNHANES) were used for analysis. The relationship between RA and hearing impairment was analyzed, adjusting for various known risk factors associated with hearing impairment. RA was defined in the questionnaire as “RA diagnosed by a physician (yes/no) through a standardized interview.” We defined hearing impairment according to 2 categories of frequency (low/mid and high) as follows (average values in kHz): low/mid frequency, 0.5, 1.0, and 2.0, and high frequency, 3.0, 4.0, and 6.0. Of the subjects, 15,158 (weighted n = 32,035,996) completed the audiometric tests. The overall weighted prevalence of RA was 1.5%. The prevalence of hearing impairment was higher in the subjects with RA than in those without RA, in both, the low/mid- and high-frequency categories (21.1% vs 7.5%, p < 0.001 and 43.3% vs. 26.2%, p < 0.001, respectively). In the multivariable logistic analysis, RA (odds ratios [OR] 1.47, 95% confidence interval [CI] 1.05–2.06, p = 0.025) was an independent risk factor of low/mid-frequency hearing impairment along with age (OR 1.12, 95% CI 1.12–1.13, p < 0.001), current smoking (OR 1.27, 95% CI 1.03–1.56, p = 0.026), and college graduation (OR 0.53, 95% CI 0.39–0.72, p < 0.001). In the multivariable analysis of high-frequency hearing impairment, RA did not show any association with hearing impairment. This study suggests that RA is associated with low/mid-frequency hearing impairment after adjustment for various known risk factors. Further study is needed to verify the hearing impairment in RA.

Status of Hearing Loss and Its Related Factors among Drivers in Zahedan, South-Eastern Iran

Objective:

This study aims to investigate loss of hearing among drivers in Zahedan, southeastern Iran.

Patients and Methods:

This study carried out on a total of 1836 drivers in Zahedan in 2013. Loss of hearing in both ears was measured at 250, 1000, 2000, 3000, 4000, 6000, and 8000 Hertz. The demographic variables, blood parameter and anthropometric data were recorded through interview and examinations. Data were analyzed in Stata.12 software using paired t-tests, McNemar test and Multiple Logistic Regression.

Results:

The mean age was 38.2±9.8 years. The highest mean hearing thresholds in the right and left ears were 25.7±9.1 and 27.7±9.1, respectively at 250 Hz. There was significant difference between left and right ears hearing threshold at all frequencies (P<0.001), and the highest difference occurred at 250 Hz. Hearing threshold in the left ear was greater than in the right ear at all frequencies. Hearing threshold was correlated to marital status, type of license, and vehicle, smoking, age, and driving history at all frequencies (P<0.01), and also significantly correlated to blood sugar and cholesterol levels at 250 and 500 Hz in both left and right ears (P<0.01).

Conclusion:

In conclusion, high levels of noise increase hearing threshold with greatest damage to the left ear. Therefore, drivers should be periodically examined for ear damage in accordance to variables affecting loss of hearing. Moreover, drivers must be educated about usage of appropriate ear-plugs during driving, especially for the left ear.

The association of obesity with hearing thresholds in women aged 18-40 years

An elevation in hearing thresholds and decrease in hearing sensitivity in adults, particularly due to aging, are quite common. Recent studies have shown that, apart from aging, various other factors also play a role in auditory changes. Studies on the association of hearing loss (HL) with obesity are limited in advanced age cases and present contradictions. In this study, the association between obesity and hearing thresholds in women aged 18-40 years has been assessed. Forty women diagnosed with obesity (mean age, 31.8 years) and 40 healthy non-obese female controls (mean age, 30.5 years) were included in this prospective study. Each subject was tested with low (250, 500, 1000 and 2000 Hz) and high (4000, 6000 and 8000 Hz) frequency audiometry. In the case and control groups, the average hearing thresholds at low frequencies were 16.03 ± 4.72 and 16.15 ± 2.72 (p = 0.885) for the right ear, respectively, and 16.15 ± 5.92 and 14.71 ± 3.18 (p = 0.180) for the left ear, respectively. The average hearing threshold levels at high frequencies were 20.70 ± 10.23 and 15.33 ± 3.87 (p = 0.003), respectively, for the right ear, and 22.91 ± 15.54 and 15.87 ± 4.35 (p = 0.007), respectively, for the left ear with statistical significance. This is the first report on the association of obesity with hearing threshold in women aged 18-40 years. We have demonstrated that obesity may affect hearing function, particularly that related to high frequencies. Hearing loss can be prevented by avoidance or control of obesity and its risk factors. Moreover, an auditory screening of obese cases at an early stage may provide early diagnosis of HL and may also contribute to their awareness in the fight against obesity.

Auditory Temporal Resolution in Individuals with Diabetes Mellitus Type 2

Introduction "Diabetes mellitus is a group of metabolic disorders characterized by elevated blood sugar and abnormalities in insulin secretion and action" (American Diabetes Association). Previous literature has reported connection between diabetes mellitus and hearing impairment. There is a dearth of literature on auditory temporal resolution ability in individuals with diabetes mellitus type 2. Objective The main objective of the present study was to assess auditory temporal resolution ability through GDT (Gap Detection Threshold) in individuals with diabetes mellitus type 2 with high frequency hearing loss. Methods Fifteen subjects with diabetes mellitus type 2 with high frequency hearing loss in the age range of 30 to 40 years participated in the study as the experimental group. Fifteen age-matched non-diabetic individuals with normal hearing served as the control group. We administered the Gap Detection Threshold (GDT) test to all participants to assess their temporal resolution ability. Result We used the independent t-test to compare between groups. Results showed that the diabetic group (experimental) performed significantly poorer compared with the non-diabetic group (control). Conclusion It is possible to conclude that widening of auditory filters and changes in the central auditory nervous system contributed to poorer performance for temporal resolution task (Gap Detection Threshold) in individuals with diabetes mellitus type 2. Findings of the present study revealed the deteriorating effect of diabetes mellitus type 2 at the central auditory processing level.

Does gestational diabetes result in cochlear damage?

BACKGROUND

Glucose metabolism has a significant impact on inner-ear physiology. Therefore, hearing may be affected in gestational diabetes.

METHOD

A matched case-control study was performed to evaluate 27 patients with gestational diabetes and 31 non-diabetic pregnant women with similar demographic characteristics. A medical history was taken for each participant, and otological inspections and high-frequency audiometry tests were performed.

RESULTS

There were no significant differences in average pure tone air-bone hearing thresholds between the groups (p > 0.05). However, evaluation of high-frequency hearing thresholds indicated significantly increased auditory thresholds at 10 kHz and 12 kHz for right ears and at 8, 10, 12 and 14 kHz for left ears in the gestational diabetes group (p < 0.001).

CONCLUSION

An investigation into cochlear damage in gestational diabetic patients showed significant high-frequency hearing loss. Further studies are needed to validate these findings in different ethnic groups and geographical populations.

Auditory Impairment in Young Type 1 Diabetics

BACKGROUND AND AIMS

More attention has recently been focused on auditory impairment of young type 1 diabetics. This study aimed to evaluate auditory function of young type 1 diabetics and the correlation between clinical indexes and hearing impairment.

METHODS

We evaluated the auditory function of 50 type 1 diabetics and 50 healthy subjects. Clinical indexes were measured along with analyzing their relation of auditory function.

RESULTS

Type 1 diabetic patients demonstrated a deficit with elevated thresholds at right ear and left ear when compared to healthy controls (p <0.01). The elevated auditory threshold was significantly related with HDL-cholesterol, diabetes duration, and systemic blood pressure (p <0.05). Moreover, latencies of right ear (wave III, V and interwave I-V) and left ear (wave III, V and interwave I-III, I-V) in diabetic group significantly increased compared to those in control subjects (p <0.01). Auditory brainstem response was significantly related with GHbA1C and microalbuminuria (p <0.01). Furthermore, distortion product evoked otoacoustic emissions (DPOAE) of diabetes group were statistically significant in right ears at 4.0, 6.0 kHz and in left ears at 4.0, 6.0, 8.0 kHz (p <0.01) compared with those of controls. Diabetic patients demonstrated lower amplitude responses of the right ear than the left ear at 8.0 kHz. Only triglyceride was positively correlated to the hearing impairment defined by DPOAE (p <0.01). There was no significance of transient evoked otoacoustic emissions (TEOAE) between groups. TEOAE was associated with age and GHbA1C (p <0.01).

CONCLUSIONS

Type 1 diabetics exerted higher auditory threshold, slower auditory conduction time and cochlear impairment. HDL-cholesterol, diabetes duration, systemic blood pressure, microalbuminuria, GHbA1C, triglyceride, and age may affect the auditory function of type 1 diabetics.

Role of Obesity on the Prognosis of Sudden Sensorineural Hearing Loss in Adults

OBJECTIVE

To investigate the role of obesity/overweight on the prognosis of sudden sensorineural hearing loss (SSHL).

STUDY DESIGN

Retrospective cohort study.

SETTING

Outpatient department of a community hospital.

SUBJECTS AND METHODS

We collected 254 adult patients with SSHL from a community hospital. The odd ratios of body mass index (BMI) or obesity/overweight (BMI ≥25 kg/m(2)) on the recovery of SSHL were evaluated with multivariate logistic regression analysis.

RESULTS

There were 120 (47.2%) patients in the nonobesity group (BMI <25 kg/m(2)) and 134 (52.8%) patients in the obesity/overweight group (BMI ≥25 kg/m(2)). The complete and partial recovery rates were 10.0% and 49.2% in the nonobesity group and 9.7% and 47.0% in the obesity/overweight group, respectively. Univariate logistic regression showed that BMI had no significant association with recovery of SSHL (odds ratio [OR] of complete and partial recovery versus no recovery = 1.04, 95% confidence interval [CI] = 0.965-1.113, P = .327). Multivariate logistic regression analysis also showed that BMI (OR = 1.04, 95% CI = 0.964-1.131, P = .292) was not significantly associated with the recovery of SSHL for all subjects, after adjusting for all considered variables. Also, obesity/overweight (BMI ≥25 kg/m(2)) had no significant association with the recovery of SSHL.

CONCLUSION

Obesity/overweight would appear to have no significant effect on the prognosis of SSHL.

No association between plasma adiponectin levels and central auditory function in adults

Adiponectin might play a protective role in cardiometabolic and peripheral auditory disorders, but its role on central auditory function was still unclear. The aim of this study was to examine whether there is an association between plasma adiponectin levels and central auditory function in adults. We recruited 297 adults, with normal or symmetrical sensorineural hearing loss and normal cognitive functions. Multivariate linear regression was performed to assess the association between plasma adiponectin concentrations and pitch pattern sequence (PPS) score, which was one of central auditory tests. The results showed that there were 224 (75.4%) women and 73 (24.6%) men in this study. The mean age was 58.1 ± 8.4 years, the mean waist circumference (WC) was 81.1 ± 8.3 cm, and the mean body mass index (BMI) was 24.0 ± 3.0 kg/m(2). The mean PPS score was 71.5 ± 14.1%, and plasma adiponectin concentration was 12.7 ± 5.5 g/mL. After adjusting for age, gender, WC, coronary artery disease, hypertension, diabetes mellitus, chronic kidney disease, smoking and drinking, plasma adiponectin concentrations (coefficient ± standard error, β ± SE = -0.09 ± 0.16, p = 0.563) were found to have no significant associations with PPS score. When WC was excluded from these variables in the multivariate linear regression model, plasma adiponectin concentrations (β ± SE = -0.03 ± 0.15, p = 0.855) were still not significantly associated with PPS score. In conclusion, plasma adiponectin levels were not significantly associated with PPS score, which was one of central auditory function tests. More studies should be conducted for the underlying mechanisms of obesity-related central auditory dysfunction.

[Evaluation of hearing loss parameters in workers and its relationship with fasting blood glucose levels]

INTRODUCTION

Hearing loss due to noise is considered within the prevention plans of the most common occupational diseases. In addition to evaluation of working conditions, other personal factors increasing the risk of hypoacusis, such as diabetes, should be taken into account.

OBJECTIVES

To explore hearing loss in the workplace and its relationship to impaired fasting baseline blood glucose levels.

METHODS

An observational, cross-sectional study enrolling 1636 workers from service companies was conducted. Full audiometric evaluation was performed at different frequencies: high frequency (HF), early loss index (ELI), speech average loss (SAL), and monaural and binaural loss. Results were categorized by baseline blood glucose levels: G1 (<100mg/dl), G2 (100-125mg/dl), and G3 (>125mg/dl).

RESULTS

Based on both HF and ELI, 11% of workers had clear indication of deafness. Women with G3 levels showed significant differences in the results of HF and ELI indexes as compared to the G1 group (P=.038 and .046, respectively). A positive association was found between hearing loss and G3 blood glucose levels in HF (OR: .338; p=.002), ELI (OR: .407; p=.007), and the monaural test in the left ear (OR: 4.77×10-5; p=.006).

CONCLUSIONS

Despite the methodological limitations of this study, there is evidence for an increased risk of high frequency hearing loss in workers with high baseline blood glucose levels.

Audiovestibular functions in noninsulin-dependent diabetes mellitus

CONCLUSION

This study supports the proposition that vestibular dysfunction and sensorineural hearing loss (SNHL) may be considered among the complications due to noninsulin-dependent diabetes mellitus (NIDDM).

OBJECTIVE

The aim of this study was to evaluate the audiovestibular functions in patients with NIDDM and to determine if there is any correlation between audiovestibular dysfunction and the duration of the disease.

METHODS

A total of 104 patients diagnosed with NIDDM and 104 nondiabetic control subjects made up the study group. Diabetic patients were also divided into subgroups of ≤7 years and >7 years according to the duration of the disease. Pure-tone audiometry (PTA), speech recognition scores (SRS), impedance audiometry, and vestibular function tests (VFT) were performed for all of the patients.

RESULTS

Hearing thresholds in all frequencies (except at 500 Hz for bone conduction) and SRS values were statistically significant in patients with NIDDM and control subjects, but there was no statistically significant difference according to the duration of the disease. Statistically significant alterations were present in VFT in patients with NIDDM compared with the control subjects. In the diabetic group, only failure in the saccade test was statistically significant according to the duration of the disease.

Investigation of auditory thresholds in type 2 diabetic patients compared to non-diabetic cases

BACKGROUND

Hearing loss is one of the common complaints of diabetics. The aim of this study was to evaluate the hearing status of diabetic patients in Babol, North of Iran.

METHODS

The hearing status of 50 type 2 diabetic patients (case group) and 50 healthy individuals (control group) were evaluated from October 2011 to September 2012. Audiometry was done with the frequencies of 250, 500, 1000, 2000, 4000, 6000, 8000 HZ and speech tests like SRT (speech reception threshold), SDS (speech discrimination score) were performed. The data were collected and analyzed.

RESULTS

The mean age of case group was 50.1±3 and in control group was 49.9±3.2 years. Hearing thresholds were 10.55.6, 10.76.1, 15.27.1, 169.6, 21.213.5, 26.416.5, 28.32 db in the right ear of the case group and 11.25.3, 9.74.9, 127.1, 14.29.4, 20.913.3, 25.115.6, 27.620.2 db in control group with different frequencies (p<0.05). Similar results were obtained in the left ear of both groups. The mean SRT in the right ear of the case group was 15.77.7 and control group was 9.24.8 and 13.56.9 in case and 9.14 in the left ear of case group (P=0.0001). SDS was 94.33.7 and in 96.23.3 in the right ear for the case and control group, respectively (P=0.0001). For the left ear, these values were 94.44.4 and 95.93.2, respectively (P=0.023).

CONCLUSION

The results show that hearing loss in different frequencies and speech reception threshold were higher in diabetic group but speech discrimination score was higher in normal individuals. Audiological monitoring is recommended in diabetic patients during therapy.

The efficacy of red ginseng in type 1 and type 2 diabetes in animals

Diabetes mellitus (DM) is one of the most modern chronic metabolic diseases in the world. Moreover, DM is one of the major causes of modern neurological diseases. In the present study, the therapeutic actions of Korean red ginseng were evaluated in type 1 and type 2 diabetic mouse models using auditory electrophysiological measurement. The comprehensive results from auditory brainstem response (ABR), auditory middle latency response (AMLR), and transient evoked otoacoustic emission (TEOAE) demonstrate auditory functional damage caused by type 1 or 2 DM. Korean red ginseng improved the hearing threshold shift, delayed latencies and signal intensity decrease in type 2 diabetic mice. Type 1 diabetic mice showed a partial improvement in decreasing amplitude and signal intensity, not significantly. We suggest that the Korean red ginseng has a more potent efficacy in hearing loss in insulin resistance type 2 diabetes than in type 1 diabetes.

Changes in brainstem auditory evoked potentials among North Indian females with Type 2 diabetes mellitus

BACKGROUND

Diabetes mellitus is a complex metabolic disorder whose detrimental effects on various organ systems, including the nervous system are well known.

AIM

This study was conducted to determine the changes in the brainstem auditory evoked potentials (BAEP) in patients with type 2 diabetes mellitus.

MATERIALS AND METHODS

In this case-control study, 116 females with type 2 diabetes and 100 age matched, healthy female volunteers were selected. The brainstem auditory evoked potentials (BAEP) were recorded with RMS EMG EP Marc-II Channel machine. The measures included latencies of waves I, II, III, IV, V and Interpeak latencies (IPL) I-III, III-V and I-V separately for both ears. Data was analysed statistically with SPSS software v13.0.

RESULTS

It was found that IPL I-III was significantly delayed (P = 0.028) only in the right ear, while the latency of wave V and IPL I-V showed a significant delay bilaterally (P values for right ear being 0.021 and 0.0381 respectively while those for left ear being 0.028 and 0.016 respectively), in diabetic females. However, no significant difference (P > 0.05) was found between diabetic and control subjects as regards to the latencies of waves I, II, III, IV and IPL III-V bilaterally and IPL I-III unilaterally in the left ear. Also, none of the BAEP latencies were significantly correlated with either the duration of disease or with fasting blood glucose levels in diabetics.

CONCLUSIONS

Therefore, it could be concluded that diabetes patients have an early involvement of central auditory pathway, which can be detected quite accurately with the help of auditory evoked potential studies.

[Hearing impairment and tinnitus in patients with type 2 diabetes]

INTRODUCTION

Hearing impairment is one of the most frequent chronic health issue. The incidence of hearing impairment and tinnitus increases with age.

AIM

The aim of the authors was to determine the prevalence of hearing impairment and tinnitus in type 2 diabetic patients and to examine the possible associations between hearing impairment and/or tinnitus and increased HbA1c levels.

METHODS

103 patients with type 2 diabetes (47 men, 56 women; age, 61.6±10.3 years, mean±SD; range, 33-88 years) evaluated at the 2nd Department of Medicine, Semmelweis University were enrolled in this study and the results were compared to those obtained from 589 type 2 diabetic (253 men, 336 women; age, 55.4±11.0 years, mean±SD; range, 26-97 years) and 15 622 non-diabetic patients (7002 men, 8620 women; age, 55.1±11.1 years, mean±SD; range, 26-98 years) who participated in a comprehensive health screening programme in Hungary. Hearing impairment was determined using the Interacoustics model AS608 screening audiometer in all patient groups. Tinnitus was evaluated with questionnaire.

RESULTS

It was found that hearing impairment and/or tinnitus occurred in a very high proportion of type 2 diabetic patients evaluated at the 2nd Department of Medicine, Semmelweis University (80% of cases) as compared to type 2 diabetic (34% of cases) and non-diabetic patients (14% of cases) enrolled in the national health screening programme. There was no significant correlation between increased HbA1c levels and hearing impairment or tinnitus in type 2 diabetic patients.

CONCLUSION

These results suggest that the prevalence of hearing impairment and tinnitus is higher and develop at an earlier age in patients with type 2 diabetes. The results indicate a high prevalence of hearing impairment and tinnitus in type 2 diabetic patients.

Brainstem auditory evoked potential abnormalities in type 2 diabetes mellitus

BACKGROUND

Diabetes mellitus represents a syndrome complex in which multiple organ systems, including the central nervous system, are affected.

AIM

The study was conducted to determine the changes in the brainstem auditory evoked potentials in type 2 diabetes mellitus.

MATERIALS AND METHODS

A cross sectional study was conducted on 126 diabetic males, aged 35-50 years, and 106 age-matched, healthy male volunteers. Brainstem auditory evoked potentials were recorded and the results were analyzed statistically using student's unpaired t-test. The data consisted of wave latencies I, II, III, IV, V and interpeak latencies I-III, III-V and I-V, separately for both ears.

RESULTS

The latency of wave IV was significantly delayed only in the right ear, while the latency of waves III, V and interpeak latencies III-V, I-V showed a significant delay bilaterally in diabetic males. However, no significant difference was found between diabetic and control subjects as regards to the latency of wave IV unilaterally in the left ear and the latencies of waves I, II and interpeak latency I-III bilaterally.

CONCLUSION

Diabetes patients have an early involvement of central auditory pathway, which can be detected with fair accuracy with auditory evoked potential studies.

Cochleopathy in Egyptian adolescents with Type 1 diabetes mellitus

BACKGROUND

Diabetic neuropathy is recognized as the most common clinical picture of nervous system disorders caused by diabetes mellitus (DM). Although peripheral and autonomic nervous system involvements are frequently encountered, data about the incidence of central diabetic neuropathies is limited.

OBJECTIVE

Our study aimed to detect early asymptomatic auditory impairment whether at the level of outer hair cells (OHCs), inner hair cells (IHCs) and or olivo-cochlear bundle and the relationship between these abnormalities and other variables such as diabetes duration, degree of the metabolic control, or presence of microvascular complications.

SUBJECTS AND METHODS

Seventy five adolescents with Type 1 DM and thirty three healthy controls participated in the study. Duration of DM, glycated hemoglobin (HbA1c) levels, microvascular complications were analyzed. All underwent basic audiological assessment to ensure normal hearing and normal middle ear function. Other tests comprised: transiently evoked otoacoustic emissions (TEOAEs) testing OHCs, TEOAEs with contralateral suppression (testing the integrity of olivo-cochlear bundle) and threshold equalizing noise (TEN) testing IHCs as evidenced by dead regions within the cochlea.

RESULTS

Early asymptomatic OHCs involvement as reflected by partial pass in 33.3% of cases with diminished suppression as compared to 9.1% control group. Eleven patients (7.33%) showed positive TEN Test reflecting resistance of IHCs to hyperglycemic injury. Diabetic patients had significantly higher amplitude on TEOAEs with noise suppression when compared to controls (P=0.002). The mean difference in amplitude of TEOAEs before and after suppression was significantly higher in diabetics with microvascular complications when compared to diabetic children without complications at all frequencies (P<0.001 for all). Duration of diabetes and microvascular complications (nephropathy, peripheral and autonomic neuropathy) were not correlated with the lack of suppression except for retinopathy (P=0.02). In contrast, poor metabolic control was associated with poor suppression (r=-0.443, P=0.001).

CONCLUSIONS

Cochleopathy can be detected in a relatively high proportion of subjects with Type 1 diabetes in spite of a normal audiometric hearing threshold. It should be considered as early manifestation of diabetic neuropathy which is related to the degree of metabolic control and retinopathy independent of other microvascular complications.

Waist circumference is associated with pitch pattern sequence score in older male adults

OBJECTIVE

While obesity may increase the risk for neurodegenerative diseases such as Alzheimer's disease, the relationship between waist circumference (WC) and central auditory dysfunction is unknown. We aimed to investigate the relationship of WC and pitch pattern sequence (PPS) score in adults.

DESIGN

The association of WC with PPS score was analysed.

STUDY SAMPLE

Volunteer helpers at a community hospital, 391 adults ≥40 years, with normal or symmetrical sensorineural hearing loss were randomly selected.

RESULTS

After adjusting for age, gender, pure-tone average, systemic diseases, and habits, WC was significantly negatively associated with PPS. In a subgroup analysis by gender and age, the PPS score was negatively associated with WC only for males who were older than 55 years old, but not for males who were younger than 55 years old or females in either age group. Meanwhile, central obesity showed positive association with abnormal PPS recognition ability (PPS score < 90%) of borderline significance only for males who were older than 55 years old, but not for males who were younger than 55 years old or females in both age groups.

CONCLUSIONS

WC or central obesity is an independent risk factor for poor central auditory function, especially in older male subjects.

Reducing a Barrier to Diabetes Education

Purpose

Recent research suggests that hearing loss, a frequent problem for aging adults, is more prevalent in people with diabetes. Hearing impairment affects a patient’s learning. This article reviews the anatomy and physiology involved in hearing, describes common causes of hearing loss in people with diabetes, and describes how hearing loss is diagnosed and treated. Two simple tests the diabetes educator can use to screen for hearing loss are described, and interventions that improve communication with patients with difficulty hearing are explained.

Conclusions

Hearing loss can negatively affect a patient’s ability to actively participate in diabetes education. Diabetes educators have a responsibility to learn how to communicate better with their patients who have a hearing impairment. Diabetes educators are uniquely positioned to improve the health status of their patients by identifying persons who need referral for further evaluation of their hearing.

Interactions of hearing loss and diabetes mellitus in the middle age CBA/CaJ mouse model of presbycusis

Recently, we characterized the more severe nature of hearing loss in aged Type 2 diabetic human subjects [Frisina, S.T., Mapes, F., Kim, S., Frisina, D.R., Frisina, R.D., 2006. Characterization of hearing loss in aged type II diabetics. Hear. Res. 211, 103-113]. The current study prospectively assessed hearing abilities in middle age CBA/CaJ mice with Type 1 diabetes mellitus (T1DM) (STZ injection) or Type 2 diabetes mellitus (T2DM) (high fat diet), for a period of 6 months. Blood glucose, body weight and auditory tests (Auditory Brainstem Response-ABR, Distortion Product Otoacoustic Emissions-DPOAE) were evaluated at baseline and every 2 months. Tone and broad-band noise-burst responses in the inferior colliculus were obtained at 6 months. Body weights of controls did not change over 6 months (approximately 32 g), but there was a significant (approximately 5 g) decline in the T1DM, while T2DM exhibited approximately 10 g weight gain. Blood glucose levels significantly increased: 3-fold for T1DM, 1.3-fold for T2DM; with no significant changes in controls. ABR threshold elevations were found for both types of diabetes, but were most pronounced in the T2DM, starting as early as 2 months after induction of diabetes. A decline of mean DPOAE amplitudes was observed in both diabetic groups at high frequencies, and for the T2DM at low frequencies. In contrast to ABR thresholds, tone and noise thresholds in the inferior colliculus were lower for both diabetic groups. Induction of diabetes in middle-aged CBA/CaJ mice promotes amplification of age-related peripheral hearing loss which makes it a suitable model for studying the interaction of age-related hearing loss and diabetes. On the other hand, initial results of effects from very high blood glucose level (T1DM) on the auditory midbrain showed disruption of central inhibition, increased response synchrony or enhanced excitation in the inferior colliculus.