Research Article, J Otol Rhinol Vol: 9 Issue: 3
Prevalence of Hearing Loss in Type 2 Diabetes Mellitus in Port Harcourt, Nigeria
Received: May 28, 2020 Accepted: June 13, 2020 Published: June 19, 2020
Citation: Osuji AE, Lilly-Tariah OBD, Unachukwu CN, Nwankwo BE (2020) Prevalence of Hearing Loss in Type 2 Diabetes Mellitus in Port Harcourt, Nigeria. J Otol Rhinol 9:3. doi: 10.3752/jor.9(3).385
Introduction:Diabetes mellitus (DM) is a chronic noncommunicable disease and chronic hyper-glycaemia is its main feature. In the presence of type 2 DM, hypertension, hyperlipidemia and obesity are common, and a cluster of these conditions is referred to as “metabolic syndrome”. Hearing loss is a common disability which can be a complication of DM or hypertension and results from microvascular disease that characterize each of these disease conditions. The aim of this study was to determine the prevalence of hearing loss in adults with type 2 DM adults in Port Harcourt, Rivers State, Nigeria. Patients and methods: This cross-sectional study was conducted in UPTH, Port Harcourt, Rivers State, Nigeria, and the study population comprised of patients with type 2 diabetes mellitus that attended medical out-patients clinic of the University of Port Harcourt Teaching Hospital, Port Harcourt, Rivers State, Nigeria. Results were analyzed statistically using SPSS 23 and presented in tables and figures. Results: There were 258 adult study participants, with 104 males and 144 females, with a male female ratio of 1:1. 4. The age range of study participants was 21- 89 years with a mean age of 55 ± 13. 17 years. The prevalence of hearing loss in this study population was found to be 32. 9%. There was no statistical difference in the gender prevalence of hearing loss in people living with DM. Conclusion: This study found that the prevalence of hearing loss among people living with Diabetes mellitus is remarkable, and significantly higher in the elderly population, and there is no significant difference in the prevalence of hearing loss between male and female adults living with diabetes mellitus. Recommendation: It is recommended that a holistic protocol of management of type 2 DM which includes hearing health assessments at regular intervals should be adopted to monitor the hearing acuity in people living with DM for early identification of hearing loss and timely intervention for treatment or rehabilitation when necessary. In addition, the need for an increased awareness campaign on hearing loss in DM cannot be over emphasized.
Keywords: Type 2 Diabetes mellitus; Port Harcourt; Hearing loss; Nigeria
Diabetes mellitus (DM) is a chronic non-communicable disease and chronic hyperglycaemia is its main feature. There are two main types of primary diabetes mellitus. Type 1 results from auto immune destruction of beta cells of the pancreas, while type 2 results from disorders of insulin secretion and metabolism. In the presence of type 2 DM, hypertension, hyperlipidemia and obesity are common, and a cluster of these conditions is referred to as “metabolic syndrome” .
Hearing loss is a common disability in humans and can be a complication of chronic diseases like DM or hypertension and results from microvascular injury that characterize each of these disease conditions. In people living with diabetes mellitus, metabolic syndrome can lead to a premature onset of macro and/or microvascular disease that can affect the cochlea, which may worsen their hearing thresholds . The Basic mechanism through which insulin and glucose levels cause change in auditory perception, is related to impairment of microcirculation, neuropathic factors and the effect of hyperglycaemia. The arteriosclerotic plaques increase the thickness of the blood vessels, leading to decreased exchange across capillary wall, with a relatively reduced blood flow through them, and reduced oxygen delivery to tissues [3,4]. Recent studies have shown hearing loss as one of the complications of diabetes mellitus and revealed the microscopic effect of DM on the cochlea .
The rising prevalence of DM globally, and especially in this sub- Saharan region calls for an increased research on hearing loss in DM, to monitor its evolving trend in our environment. In Africa, prevalence of DM in the rural areas was reported to be 1% however in the urban area of sub Saharan Africa, it is as high as 7% . In more developed areas in South Africa, prevalence of diabetes has been reported to be 8%-13% . The prevalence in Nigeria varies from 0. 65% in rural Mangu (Northern Nigeria) to 6. 0% in Sokoto, and 11% in urban part of Lagos (southern Nigeria) . However, Mezie-Okoye reported a much higher prevalence of 25. 2% in 2006, when she studied a rural community in south east Nigeria . According to WHO, Nigeria has the highest number of people living with diabetes in Africa . From when the various studies reporting the various prevalence of DM were conducted, there may have been an increase, which can only be detected by indigenousresearch into this pathology and its effects on the people in our region. This highlights the need tocontinuously beam our research light on diabetes and its complications.
The aim of this study isto determine the prevalence of hearing loss in adults with type 2 DM adults in Port Harcourt, Rivers State, Nigeria.
Patients and Method
This prospective cross-sectional study was conducted in UPTH, Port Harcourt, Rivers State, Nigeria, and the study population comprised of patients with type 2 diabetes mellitus that attended medical out-patients clinic of the University of Port Harcourt Teaching Hospital, Port Harcourt, Rivers State, Nigeria, between January to June 2018, 258 adults with DM were drawn from this study population. The Inclusion criteria was Patients seen in the medical out-patients clinic diagnosed with type 2 diabetes mellitus according to the World Health Organization (WHO) diagnostic criteria , Fasting plasma glucose ≥ 7 mmol/l orHb A1C ≥ 6. 5%, who are aged 18 years and above. Pure tone hearing threshold was carried out in a soundproof booth according to the Modified Hughson-Westlake Procedure . The prevalence of hearing loss was estimated as hearing impairment in the better hearing ear of the study participants. Ethical approval was obtained from the University of Port Harcourt Teaching Hospital Ethical Review Committee, and written informed consent was obtained from the participants. Results were analyzed statistically using SPSS 23 and presented in tables and figures. A p value of ≤ 0. 05 was considered significant.
There were 258 adult study participants, with 104 males and 144 females, with a male female ratio of 1:1. 4. The age range of study participants was 21-89 years with a mean age of 55 ± 13. 17 years. The prevalence of hearing loss in this study population was found to be 32. 9%.
Table 1 shows that the prevalence of hearing loss in males (38. 5%) in this study is higher than the prevalence of hearing loss in females (29. 2%), irrespective of the female preponderance in the study. However, the difference was not statistically significant with p value being greater than 0. 05 (p value=0. 129).
|Sex||N = 76 n (%)||N = 34 n (%)||N = 110 n (%)|
|Male||40 (38. 5)||64 (22. 7)||104 (100. 0)|
|Female||45 (29. 2)||109 (36. 4)||154 (100. 0)|
|Chi-square p value = 0. 129|
Table 1: Prevalence of hearing loss in males and females.
Table 2 shows the age distribution of the subjects in age categories. It shows that the age group with the highest number of diabetes mellitus is in the age group of 50-59 (71), followed by age group of 60-69 (70).
|Age category (years)||Total N (%)|
|20-29||3 (1. 2%)|
|30-39||34 (13. 2%)|
|40-49||39 (15. 1%)|
|50-59||71 (27. 5%)|
|60-69||70 (27. 1%)|
|70-79||32 (12. 4%)|
|80-89||9 (3. 5%)|
Table 2: Frequency distribution of subjects by age category.
Table 3 shows the prevalence of hearing loss according to age categories ≤ 59 years and ≥ 60 years. It shows that the prevalence of hearing loss in subjects aged 60 years and above (49. 5%) is greater than the prevalence of hearing loss in subjects aged ≤ 59 years (20. 2%).
|Age category||Yes N (%)||No N (%)||Total N (%)|
|≤ 59 years||30 (20. 2)||117 (79. 6)||147 (57. 0)|
|≥60 years||55 (49. 5)||56 (50. 5)||111 (43. 0)|
|Total||85 (32. 9)||173 (67. 1)||258 (100)|
|Chi square p value=0. 018*|
Table 3: prevalence of Hearing loss in subjects according to age categories ≤ 59 years and ≥ 60 years.
The prevalence of hearing loss in the study participants was found to be 32. 9%. This is higher than 21. 6% seen by Adebola et al in their work in Osogbo , and lower than 46. 9% reported by Nwosu and Chime in Enugu  and 71. 8% seen by Yikawe et al in Sokoto  despite the fact that all were also hospital-based and cross-sectional studies like this study. The reason for the higher prevalence of hearing loss in DM in the Northern part of Nigeria may be because of late presentation to hospital, and probably poor drug compliance, with resultant poor glycaemic control. These culminate in higher rate of complication from the disease progression. In this study region, which is the southern part of Nigeria, the effect of urbanization, with high rate of patronage of “fast food” with the resultant consumption of highly refined food and drinks may be responsible for prevalence of DM. However, the complications of DM can be due to the high cost of living and hospital services, relative to a low economic power which implies poor affordability for hospital attendance and treatment cost. This in turn leads to late presentation, and poor drug compliance responsible for this high prevalence of hearing loss in DM. A factor promoting this deplorable recurrent trend is the Nigerian form of healthcare practice where patients pay out of pocket for every treatment or procedure they require in the hospital. However, the various prevalence from different parts of the country, irrespective of the factors responsible, show that the magnitude of hearing loss in adults with DM in Nigeria isremarkable and calls for a quick review of our present protocol of DM management.
There was female preponderance in this study, however, the difference in the hearing thresholds of males and females was not statistically significant, with p value greater than 0. 05. This may suggest that gender has no significant effect on hearing thresholds. Similarly, Yikawe et al.,  and Bhaskar et al.,  found no association between gender and hearing loss. However, Ogundiran and Olaosun who worked on hearing loss in elderly population with DM, reported that elderly men who have DM, have a higher prevalence of hearing loss when compared to the elderly females, and that hearing loss progresses faster in males than in females . They opined that this results from lifelong exposure to loud noise in the line of male occupation and hustle. Some authors have stated that the hearing loss does not depend on the sex of the individual, but rather on other factors such as the duration of the DM, and individual genetic predisposition to complications of DM and hearing loss [14,16].
This study noted that despite the age range of 21-89 years, prevalence of hearing loss was more in the elderly population of 60 years and above when compared to the younger population less than 60 years. Similarly, Cayonu et al., in their study noted the presence of a higher prevalence of hearing loss in 60 years and above and went further to state that the effect of presbycusis in this age group may be masking the true association between diabetes mellitus and hearing loss . On the other hand, the higher prevalence of hearing loss in this elderly population can also be attributed to a longer lasting disease condition. This is because they may have experienced more repeated episodes of hyperglycaemia. This is in line with the findings of Mozaffari et al.,  and Austin et al.,  who opined that repeated episode of hyperglycaemia, over time, leads to a chronic effect on the subjects hearing threshold, thereby exposing the affected individual to the complications of DM as the disease progresses. Therefore, the duration of DM becomes a greater determinant of hearing loss as regards the effect of raised blood sugar . Horikawa et al.,  in their study in the non-elderly population, also stated that ageing is not a factor responsible for hearing loss, but rather hearing loss in DM is a result of the disease progression.
This study found that the prevalence of hearing loss among people living with Diabetes mellitus is remarkable, and significantly higher in the elderly population, and there is no significant difference in the prevalence of hearing loss between male and female adults living with diabetes mellitus.
It is recommended that a holistic protocol of management of type 2 DM which includes hearing health assessments at regular intervals should be adopted to monitor the hearingacuity in people living with DM for early identification of hearing loss and timely intervention for treatment or rehabilitation when necessary. In addition, the need for an increased awareness campaign on hearing loss in DM cannot be over emphasized.
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