Abstract
To study the prevalence of SNHL in type 1 diabetes mellitus with uncontrolled HbA1c. Prospective study. 72 patients in the age group < 18 yrs were taken for study, who were diagnosed with type 1 diabetes mellitus in department of medicine, paediatrics and endocrinology and willing to undergo ENT examination. The patients with type 2 diabetes mellitus, a history of ear disease, head or ear trauma, history of use of ototoxic drugs, with family history of congenital deafness or previously operated ear and exposure to excessive noise were excluded. A complete ENT examination was done. Written consent was taken from the parents. A note was made of the HbA1c values of the patient of last 1 year in order to classify them as controlled diabetics with regular insulin therapy and uncontrolled diabetics with irregular insulin therapy. The cut off value of HbA1c was taken as 7%. On the basis is glycemic control, the patients were divided in 2 categories, controlled (HbA1C less than 7%) and uncontrolled (HbA1C greater than 7%). The type, degree and frequency of hearing impairement were determined by pure tone audiometry (PTA) (at 500, 1000, 2000 and 4000 Hz).The degree of hearing impairement was classified according to the WHO classification. 72 patients who had type 1 diabetes mellitus were evaluated using pure tone audiometry for hearing assessment. The factors taken into consideration for studying the impact on hearing loss was gender of the patients and HbA1c value. A P value of > 0.05 was seen in case of gender of the patients and a P value of < 0.05 was seen in regard to HbA1c value. Type 1 diabetes mellitus patients with deranged HbA1c and uncontrolled diabetes have higher incidence of hearing loss as compared to the Type 1 diabetes mellitus patients with controlled disease. Therefore if patients have a controlled sugar levels with regular HbA1C monitoring, this can have a preventive action on the SNHL as compared to the patients with uncontrolled HbA1C.
Keywords: Diabetes mellitus, HbA1C, Hearing loss
Introduction
Type 1 diabetes is associated with various comorbidities including sensory neural hearing loss (SNHL). Approximately 9.2 per 1000 individuals with type 1 diabetes mellitus develop SNHL each year [1]. The reported prevalence of SNHL is up to 33% in children with T1DM versus 0.3–0.5% in healthy children [2]. Type 1 diabetes mellitus (T1DM) is a disease with an etiology of intervening environmental factors which interact with a genetic-predisposition component; it is considered a chronic autoimmune disease which causes the destruction of the pancreatic β cells which produce insulin [3].
The affection of blood vessels which supply the inner ear and vascular striae has been reported as physiopathological cause of sensorineural hearing loss in type 1 diabetic mellitus patients. Treatment with insulin, maintaining on average HbA1c of 7.2%, reduces the onset and progression of microangiopathic complications [4].
According to the World Health Organization, approximately 466 million people worldwide suffer from disabling hearing loss, while over one billion young adults are at risk of developing hearing impairment, marking it as a significant global health concern [5].
Sensorineural hearing loss (SNHL) is a loss of hearing at 25 dB more than the hearing frequency, and affecting the patient's ability to communicate, his or her education, job prospects and social relationships, and also causes stigmatisation [6, 7]. Most audiometric studies of hearing in patients with diabetes show a mild to moderate high frequency SNHL [8].
Conducted studies have reported a relationship between HbA1c and hearing loss [9–11].
Good control of diabetes mellitus should supposedly be associated with slower progression of hearing impairment.
Material and Methods
The present study was conducted in the Department of Otorhinolaryngology at the Mahatma Gandhi Medical college and Hospital from 01 September 2022 to 31 March 2024.Institutional Ethics Committee approval was taken prior to the commencement of the study. It was a Prospective, Observational, hospital-based study.It was done to find the prevalence of SNHL in type 1 Diabetes Mellitus patients and the impact of sex and HbA1c level in SNHL.
72 patients in the age group < 18 yrs were taken for study, who were diagnosed with type 1 Diabetes mellitus in department of medicine, paediatrics and endocrinology and willing to undergo ENT examination. The patients with type 2 diabetes mellitus, a history of ear disease, head or ear trauma, history of use of ototoxic drugs, congenital deafness, children with syndromes and endocrine abnormalities,family history of congenital deafness or previously operated ear and exposure to excessive noise were excluded.
A complete ENT examination was done. Written consent was taken from the parents.
A note was made of the HbA1c values of the patient of last 1 year in order to classify them as controlled diabetics with regular insulin therapy and uncontrolled diabetics with irregular insulin therapy. The cut off value of HbA1c was taken as 7%. On the basis is glycemic control, the patients were divided in 2 categories, controlled(HbA1C less than 7%) and uncontrolled (HbA1C greater than 7%).
The type, degree and frequency of hearing impairement were determined by PTA ( Pure Tone Audiometry)(at 500, 1000, 2000 Hz and 4000 Hz).The degree of hearing impairement was classified according to the WHO classification mentioned below.
< 25 dB—normal, 26–40 dB—mild, 41–60 dB—moderate, 61–80 dB—Profound and > 80 dB—profound SNHL.
Result
A study was performed with 72 adolescents, out of which 39 (54.1%) were males and 33(45.8%) were females. Male to female ratio 1.18:1.
A table was made and noted that amongst the 23 patients having SNHL 9 were males and 14 were females. The Chi-square value was found to be 3.325 with degree of freedom 3. The “p” value = 0.344066 > 0.05 null hypothesis is accepted there is no relationship between SNHL and sex of the diabetic patients. Hence there was no correlation with the sex of the diabetic patients with hearing loss (Table 1; Fig. 1).
Table 1.
Hearing loss against gender of the patients
| PTA | Gender | Total | ||
|---|---|---|---|---|
| Male | Female | |||
| Normal | Count | 30 | 19 | 49 |
| % within PTA | 61.20% | 38.70% | 100% | |
| Mild | Count | 5 | 7 | 12 |
| % within PTA | 41.60% | 58.30% | 100% | |
| Moderate | Count | 3 | 6 | 9 |
| % within PTA | 33% | 67% | 100% | |
| Severe | Count | 1 | 1 | 2 |
| % within PTA | 50% | 50% | 100% | |
| Total | Count | 39 | 33 | 72 |
| % within PTA | 54.10% | 45.80% | 100% | |
Fig. 1.
Hearing loss against sex of the patients
The cutoff value of HbA1c in controlled diabetics is 7%. The reference values for HbA1c are normal = < 5.7%, between 5.7–7% considered pre-diabetes and > 7% considered diabetes.
In our study out of 72 patients, 48 patients had HbA1c > 7% and 24 had HbA1c < 7%. A table was made showing the degree of hearing loss with the HbA1c status of the patients. The Chi -square value of the table was found to be 34.752709 with degree of freedom 6. The p value = 0.000004811914 < 0.05 null hypothesis is not accepted there is significant relationship between SNHL and HbA1c of the patients.
Hence there is a correlation between the HbA1c value and hearing loss and the incidence of hearing loss is more in the patients with uncontrolled HbA1c value (> 7%) (Table 2) (Fig. 2).
Table 2.
Hearing loss against HbA1c of the patients
| PTA | HbA1c | Total | |||
|---|---|---|---|---|---|
| < 6.5 | 6.5 to 10 | > 10 | |||
| Normal | Count | 21 | 27 | 1 | 49 |
| % within PTA | 42.80% | 55.10% | 2.00% | 100% | |
| Mild | Count | 2 | 6 | 4 | 12 |
| % within PTA | 16.60% | 50.00% | 33.30% | 100% | |
| Moderate | Count | 1 | 2 | 6 | 9 |
| % within PTA | 11% | 22% | 66.6 | 100% | |
| Severe | Count | 0 | 0 | 2 | 2 |
| % within PTA | 0% | 0% | 100% | 100% | |
| Total | Count | 24 | 35 | 13 | 72 |
| % within PTA | 33.30% | 48.60% | 18.05% | 100% | |
Fig. 2.
Hearing loss against HbA1c of the patients
The Age of the patients against the Gender of the patients are given in Table 3.
Table 3.
Age against Gender of the patient
| Age | Gender | |
|---|---|---|
| Male | Female | |
| Below 10 years | 9 | 7 |
| 10 to 12 years | 11 | 10 |
| 13 to 15 years | 12 | 7 |
| 16 to 18 years | 7 | 9 |
| Total | 38 | 34 |
Discussion
In our present study we found out that there is a correlation of the HbA1c of the diabetic patient and hearing loss, and there is no relation between the sex of the diabetic patient and hearing loss. The role of type 1 diabetes mellitus in hearing loss is highly controversial and the confounding factor in our study is the duration of Diabetes, age.
Hearing loss occurs more often in diabetes and a few hypotheses have emerged as to what might be behind this phenomenon including but not limited to role of glycated metabolites, microvascular causes and oxidative stress. The detrimental effect of glycated metabolites is theoretically based on the positive correlation between HbA1C levels and the increase of the subjective hearing threshold measured at 250–500 Hz in the case of patients with diabetes. The correlation between blood sugar level and the hearing threshold changes (at 250 and 500 Hz) have also been showed [12]. A possible connection between microangiopathy and hearing loss was that the degree of hearing loss was positively correlated with the serum creatinine value–which might refer to nephropathy–in diabetes patients with sensorineural hearing impairment [13].
There have been many studies performed before which support our present findings of the study. Dąbrowski et al. performed a study to investigate whether there is a correlation between hearing function and renal function in adults with T1D [14]. The cohort consisted of 31 patients, who had a diagnosis of T1D, 9 of whom were women, no correlation with sex was found. Braffett et al. by conducting a follow up study performed by Schade et al. [15]. It was observed that speech-frequency SNHL was significantly associated with older age, male sex, less education, loud noise exposure, increased height/weight/waist circumference, hypertension, higher lipid levels, higher HbA1C, higher insulin dose, and presence of diabetic complications. Poovazhagi et al. [16] in their study prevalence and degree of hearing loss, its distribution in different frequencies and its risk factors in children with type I diabetes mellitus (DM).included 28 males and 34 females but no correlation was found. In our present study sex of the patients was also taken in almost equal proportion, with 39 males and 33 females among total of 72 patients and no correlation was found.
A positive correlation which was found in our study that the diabetes Mellitus patients with deranged HbA1c had higher incidence and degree of hearing loss. Hence, we could easily find a similarity between our results of the present study and the previous studies as performed by clinicians and research. Okhovat et al. [17] in their study concluded that positive correlation with duration of disease and glycemic control reflected by HbA1C concentration. Schade et al. [18] stated that For every 10% increase in the time-averaged mean HbA1c (e.g., from 7 to 7.7%), a 32% and 19% increased odds of speech- and high-frequency hearing impairment was demonstrated. Mean HbA1c levels over time in the participants with type 1 diabetes provided a robust assessment of the impact levels of long-term glycemic control on hearing impairment.
There were many studies which were conducted but were failed to see any correlation with type 1 Diabetes Mellitus and hearing loss in children studies by Sieger et al. [19], Osterhammel et al. [20] and Parving, et al. [21] failed to show any ill effect of diabetes on hearing as tested by clinical and audiologic methods. El Shafei et al. [22] also performed a randomized case control study to better understand how T1D affects the auditory system in children. The study consisted of 25 children with T1D and 25 non-diabetic controls, all aged 6–18 years old. This study did not observe statistically significant results regarding SNHL in individuals with T1D compared to the control group.
The advantage of our study was that we could find positive correlation of uncontrolled type 1 Diabetes Mellitus with SNHL and this could be prevented with a controlled sugar level of the patient. The limitation was that the long follow-up of the patient was challenging because of the non compliance of the patient.
Conclusion
Type 1 Diabetes Mellitus patients with deranged HbA1c and uncontrolled diabetes have higher incidence of hearing loss as compared to the type 1 diabetes mellitus patients with controlled disease. Therefore if patients have a controlled sugar levels with regular HbA1C monitoring, this can have a preventive action on the SNHL as compared to the patients with uncontrolled HbA1C.
We can also do further studies with long term follow-up in order to access the hearing of patients with controlled HbA1C.
Footnotes
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