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| ORIGINAL ARTICLE |
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| Year : 2018 | Volume
: 24
| Issue : 2 | Page : 80-82 |
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A prospective, observational study of incidence of sensory neural hearing loss in diabetes mellitus patients
Swati Dadhich, Sushil G Jha, Vikas Sinha, TU Samanth
Department of ENT, Government Medical College, Bhavnagar, Gujarat, India
| Date of Web Publication | 4-Sep-2018 |
Correspondence Address:
Dr. Swati Dadhich
Room No 701, Girls Hostel Sit Hospital, Jail Road, Bhavnagar, Gujarat
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/indianjotol.INDIANJOTOL_135_16
Aims and Objective: To find out the incidence of hearing loss among the type 2 diabetes mellitus patients. Materials and Methods: Study included 100 diabetic mellitus patients at least for 3 years. It is an observational study carried out for 1 year. Fasting blood sugar, PP2BS, random blood sugar, pure tone audiogram were done. Results: In this study, 100 diabetic patients were studied; out of them, 73 patients were having sensorineural hearing loss (SNHL). Out of 73 SNHL diabetic patients, 48 patients are having mild SNHL (65.75%), 21 patients are having moderate SNHL (28.76%), one patient of mod severe SNHL (1.37%), and three patients of severe SNHL (4.11%). Conclusion: The diabetic individuals had higher hearing threshold with bilateral mild to moderate degree SNHL. Gender of diabetic patient had no significant correlation with hearing loss. Duration of diabetes had significant correlation with hearing loss. Blood glucose level had strong association with SNHL.
Keywords: Diabetes mellitus, fasting blood sugar, pure tone audiogram, random blood sugar, sensorineural hearing loss
How to cite this article:
Dadhich S, Jha SG, Sinha V, Samanth T U. A prospective, observational study of incidence of sensory neural hearing loss in diabetes mellitus patients. Indian J Otol 2018;24:80-2 |
How to cite this URL:
Dadhich S, Jha SG, Sinha V, Samanth T U. A prospective, observational study of incidence of sensory neural hearing loss in diabetes mellitus patients. Indian J Otol [serial online] 2018 [cited 2019 Sep 21];24:80-2. Available from: http://www.indianjotol.org/text.asp?2018/24/2/80/240565 |
| Introduction | |  |
Patients with diabetes mellitus (DM) often show symptoms such as dizziness, tinnitus, and hearing impairment. In general, hearing loss is sensorineural, which is sometimes confused with presbycusis, mainly because it develops in patients older than 60 years of age.[1]
Diabetes mellitus is a disease in which glucose serum levels are high due to relative or absolute insulin deficiency. It causes metabolic, vascular, and neuropathic complications, affecting all the system in the body. Diabetes is incurable disease; hence, management should be focused on preventing chronic complications.[2] Hearing loss exists when there is diminished sensitivity to the sounds normally heard. Sensorineural hearing loss (SNHL) is caused by lesions of either the inner ear (sensory), the auditory (8th) nerve, or central auditory pathways.[3] There were three theories about the pathogenesis of hearing loss caused by DM: neuropathy, angiopathy, and association of both.
Pathophysiology
The angiopathy found in diabetic patients contributes to greater evidences of hearing loss. In favor of this hypothesis, histopathological findings of microvascular lesions of the inner ear, such as thickness of basal membrane of stria vascularis capillaries, as well as the fact that diffuse vascular affections caused by DM.[4],[5],[6],[7],[8],[9] Diffuse thickening of basal membranes, observed in the vascular endothelium, is one of the most prevalent morphologic findings in DM, referred to as diabetic microangiopathy. There are morphologic disorders related to the involvement of lower extremity motor and sensorial nerves, characterized by injuries to Schwann cells, myelinic degeneration, and axonal damage.[10] Arteriosclerosis, frequently seen in conjunction with DM, may also contribute to the onset of neuropathies, as it interferes with the nutrient transfer.[4],[11] Angiopathy may occur both directly interfering with cochlear blood supply and reducing nutrient transportation as a result of capillary wall thickening and indirectly reducing flow in a narrowed vasculature or, yet, causing secondary degeneration of the eighth cranial nerve.[12] Capillary wall thickening and the reduced lumen more commonly affect the internal auditory artery. Spiral ganglion neuron atrophy and eighth cranial nerve demyelination in diabetic individuals indicating that demyelination is also an early injury to extremity peripheral nerves in DM and that myelin metabolic disorders may be relevant in the pathogenesis of diabetic neuropathy.[4]
Causes of sensorineural hearing loss
Congenital, exposure to loud noise, head trauma, DM, virus or disease, autoimmune inner ear disease, hearing loss that runs in the family, aging (presbycusis), malformation of the inner, Meniere's disease, otosclerosis, and tumors.[13]
| Materials and Methods Used | | |
”A Prospective, Observational, Study of incidence of sensory neural hearing loss in DM patients” was carried out in 100 patients with known case of diabetes at least for 3 years, in Department of ENT, Government Medical college, Bhavnagar. Before the medical examination, individuals completed self-administered questionnaires about medical history and lifestyle including smoking habit, average number of cigarettes smoked daily, and the weekly frequency of alcohol intake as none or regularly.
Inclusion criteria
(i) Patients with high blood sugar level (fasting blood sugar, PP2BS, random blood sugar), (ii) known case of DM at least for 3 years, (iii) both the TM must be intact and normal, and (iv) age 30–59 years.
Exclusion criteria
(i) Family history of deafness, (ii) history of chronic suppurative otitis media (CSOM), meningitis, head or ear trauma, (iii) history of chicken pox, smallpox, malaria, jaundice, typhoid, (iv) history of ear surgeries performed in the past, and (v) history of ototoxic drug intake, chronic smoking, alcohol, radiotherapy, autoimmune diseases, and systemic diseases such as hypertension, cardiac diseases and renal failure and occupational noise exposure.
Threshold determination is done for both air and bone conduction using pure tone audiogram (PTA). The random, fasting and postprandial blood glucose levels, and hemoglobin A1c were estimated to find the glycemic status and serum urea and creatinine levels to rule out diabetic nephropathy. To assess the degree of hearing loss, WHO classification (1980) on the basis of PTA taking the average of the thresholds of hearing for frequencies of 500, 1000, and 2000 is used.[14] Degree of hearing loss – mild: 26–40 dB, moderate: 41–55 dB, moderately severe: 56–70 dB, severe: 71–90 dB, and profound: more than 90 dB.
| Results | | |
In this study, 100 diabetic patients were studied, out of them, 73 patients were having SNHL. The number of females was more than number of males. There were 52 (52%) females and 48 (48%) males in the study. Age range of the diabetic patient studied was 31–59 years, with maximum number of patients, i.e., 91 (91%) were in 41–59 years age group.
Out of 73 diabetic SNHL patients, 34 patients (46.88% of total SNHL patient) come in the age group of 51–59 years and 33 patients (45.20% of total SNHL patient) come in the age range of 41–50 years.
Out of 73 SNHL diabetic patients, 48 patients are having mild SNHL (65.75%), 21 patients are having mod SNHL (28.76%), one patient of mod severe SNHL (1.37%), and four patients of severe SNHL (4.11%). [Table 1] shows that the most number of diabetic patients are between 51-59 years. In [Table 2] it depicts that between 51-59 yrs maximum percentage of patients have SNHL. [Table 3] explains that most diabetic patients have Mild SNHL. [Table 4] explains the relation between number of diabetic years and SNHL. [Table 5] shows the prevalence of hearing impairment with age. | Table 2: Sensorineural hearing loss and age distribution of diabetic patient
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 | Table 3: Degree of sensorineural hearing loss in diabetic patient (n=73)
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It was observed that duration of diabetes directly affects the hearing of patients regardless of any age group. Patients who were having diabetes more than 8 years, all were having SNHL, due to long-term effect of diabetic microangiopathy and neuropathy. In this study, 79 patients were having diabetes for 3–7 years; out of these 79 diabetic patients, 52 patients (66.66%) were having SNHL. Out of 52, 45 were having MILD SNHL (86.53%) and 7 MOD SNHL (13.46%). A total of 13 diabetic patients for 8–12 years of diabetic duration were having SNHL, and out of 13, three patients (23.07%) were having MILD SNHL and ten patients (76.92%) of MOD SNHL. A total of five diabetic patients for 13–17 years of diabetic duration were having SNHL, and out of 5, four patients (80%) were having MOD SNHL and one patient (20%) of SEVERE SNHL. A total of three diabetic patients for 18–22 years of diabetic duration were having SNHL, and out of 3, one patient (33.33%) was having MOD TO SEVERE SNHL and two patients (66.66%) of severe SNHL.
In this study, it was observed that mod and severe SNHL was more found in long-term diabetic patients mostly 8 years and more, and the higher and mid frequencies were affected more in all diabetic patients who were having SNHL.
| Discussion | | |
It is evident from a review of otolaryngology literature that the relationship between diabetes and SNHL is complex. In our study, hearing status in patients with DM was evaluated. It was observed that 73% diabetics had SNHL which is similar to study by Taylor and Irwin in 1978 who reported that almost 70% of their adult diabetics had hearing impairment [12] and also similar to study by Rajendran in 2011 who observed 73% diabetic patients having SNHL.[15] However, in 1975, Friedman et al. observed a 55% incidence of hearing loss in diabetic patients.[16] Age could play a role in hearing loss. Age-related hearing loss was defined as mid to late adult onset, bilateral, and progressive sensory neural hearing loss where underlying causes have been excluded.[17] This excludes hearing loss caused by primary factors including loud noise exposure, underlying medical conditions (diabetes, atherosclerosis, hypertension), intrinsic otological disease (otosclerosis, CSOM), head injury, and ototoxic drug therapies.[17] It usually manifests at the age of 65 years.[3]
Marked increase in the rate of progression of hearing loss once into the sixth decade. Age-related audiogram reveals greatest hearing loss at higher frequencies.[18]
In this study, patient's age group is 31–59 years, considering increase in progression of age-related hearing loss in the sixth decade. In this study, 39 patients were in the age group of 41–50 years; out of them, 34 patients were having SNHL and 52 patients were in the age group of 51–59 years; out of them, 34 were having SNHL, affecting mid and higher frequencies both. This suggests that diabetes is the main causating factor; it may be associated factor with age-related hearing loss in some patient. As the diabetes accelerate the aging process, Axelsson et al. showed that the incidence of pure tone hearing loss increases with age in patients with diabetes, even after correction for senile deafness.[19]
| Conclusion | | |
In this study, most of diabetic patients are having bilateral mild to moderate SNHL. Gender of diabetic patient had no significant correlation with hearing loss. Duration of diabetes had significant correlation with hearing loss. Diabetic patients with poor control of blood glucose level have increased risk of hearing loss.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
| References | | |
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| 2. | Chacra AR. Diabetes mellitus. In: Prado FC, Ramos JA, Borges DR, Rothschild HA, editors. 20 th ed. São Paulo: Artes Médicas, Câmara Publicadora do Livro; 2001. p. 375-89. |
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| 7. | Raynor EM, Carrasco VN, Prazma J, Pillsbury HC. An assessment of cochlear hair-cell loss in insulin-dependent diabetes mellitus diabetic and noise-exposed rats. Arch Otolaryngol Head Neck Surg 1995;121:452-6. |
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| 13. | Hearing Loss Association of America. |
| 14. | ISO: R 389-1970 International Caliberation of Audiometers. |
| 15. | Anandalakshami RS, Mythili B, Rao V. Evaluation of incidence of Sensorineural hearing loss in patient with type 2 diabetes mellitus. Int J Biol Med Res 2011;2:982-7. |
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| 17. | Baguly DM. Scott Brown Book. 7 th ed. ch. 238a. 2010. p. 3539. |
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]
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