Diabetes Mellitus and Hearing Loss: A Complex Relationship

Abstract

Background and Objectives: Discussion is open about the relationship between diabetes (DM) and hearing loss (HL). There is a lot of evidence in the literature suggesting a causal link between these conditions, beyond being considered simple comorbidities. The difficulty in identifying populations free from confounding factors makes it difficult to reach definitive conclusions on the pathophysiological mechanisms at play. Nonetheless, there is numerous evidence that demonstrates how the population affected by DM is more affected by sensorineural HL (SNHL) and exhibit a higher prevalence of idiopathic sudden sensorineural HL (ISSNHL). Materials and Methods: Articles reporting potentially relevant information were reviewed, and the most significant results are discussed in this article. Starting from the possible mechanisms relating to auditory impairment in the diabetic condition, this article summarizes the studies on auditory evaluation in subjects with DM1 and DM2 and addresses the relationship between DM and ISSNHL. Results: DM is considered a risk factor for SNHL, although some studies have reported no relationship when the associations were adjusted for age, gender, and hypertension. Macro and microvascular insults that cause decreased blood flow, oxygen exchange, and ion transport are major complications of hypertension and DM and can have a direct effect on the sensory and support cells of the cochlea. Conclusions: Given the difficulty of carrying out studies on populations without confounding factors, new laboratory studies are strongly required to clarify which specific physiopathological mechanisms underlie the diabetic damage caused to the hearing organs and how pharmacological management may contribute to counteracting the pathophysiological effects of the diabetic condition on the auditory system.

Acoustic properties of composites materials based on bentonite and coconut or cactus (nopal) fibers

“…This is attributed to the hydrophilic properties of mucilage contained in the nopal, such that water is not adsorbed and the acoustic properties are preserved. 21,22

Figure 10.Absorption, reflection, and transmission coefficients after humidity tests of bentonite, coconut fiber, and nopal fiber.

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“…Figure 5(c) shows the images of the nopal, in this, the fibers cannot be identified; however, bright parts can be identified, which are marked with red circles and are attributed to the presence of a natural resin, mainly nopal mucilage (polysaccharide composed mainly of hemicellulose, cellulose, and pectin). 21,22 In the SEM micrograph, the nopal fibers are observed with widths of 0.1-0.5 μm and lengths that reach 4 μm, although apparently, they reach a larger size. and (f)), it can be seen how the fibers were randomly dispersed in the bentonite, in the case of coconut, the fibers distributed in the sample can be appreciated, and in the case of nopal composites, a dispersion of the fibers can be distinguished thanks to its green color present in the sample.…”

“…This is attributed to the hydrophilic properties of mucilage contained in the nopal, such that water is not adsorbed and the acoustic properties are preserved. 21,22 Figure 11 shows the graphs of the acoustic coefficients for the coconut and nopal composite after the surfacewetting process. The reflection coefficient presents an increase in amplitude proportional to the increase in water amount, the opposite for the absorption coefficient and transmission because there is a reduction in amplitude with the rise in the amount of water amount in the samples.…”

“…The acoustic coefficients of reflection, transmission, and absorption of all the composites were obtained in frequencies from 50 to 10, 000 Hz. It is important to note that the audible interval goes from 20 to 20,000 Hz; 18 however, there are reports of effects on human health due to exposure to frequencies above 5,000 Hz; [19][20][21] for this reason, it is important to evaluate acoustic barriers at intervals higher wide. Additionally, the effect of temperature and humidity on the acoustic coefficients was studied; the experiments were carried out at 30, 50, and 70°C, and the humidity process was controlled by adding a drop of water to each sample during four cycles.…”

Association Between Triglyceride-Glucose Index and Hearing Threshold Shifts of Adults in the United States: National Health and Nutrition Examination Survey, 2015–2016

“…Three recent meta-analyses have demonstrated a close association between diabetes and Sensorineural Hearing Loss. [23][24][25] Another cohort study based on NHANES dataset has also shown that diabetes patients might be exposed to a higher risk of hearing loss 26 Further, Loprinzi et al studied the relationship between biomarkers for cardiovascular disease and hearing sensitivity with the NHANES database and ascertained a positive correlation between human insulin levels and high-frequency hearing thresholds. 27 Additionally, Braffett et al recruited 1150 participants for a hearing study in the Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) and observed in follow-ups the relevance of higher HBA1c level to HL in speech and high frequencies in 2019.…”