Clinical Study to Evaluate the Association Between Sensorineural Hearing Loss and Diabetes Mellitus in Poorly Controlled Patients Whose HbA1c >8

Abstract

The relationship between sensorineural hearing loss (SNHL) and Diabetes mellitus has been known since more than 150 years. The pathophysiology of diabetes related hearing loss is speculative. Hearing loss is usually, bilateral, gradual onset, affecting higher frequencies. This study aims at knowing the prevalence of SNHL in DM and its relation to age, sex, duration of DM and control of DM. A total of 50 type 2 diabetics of age group 30-65 years were involved in the study. FBS, PPBS, HbA1c of all the subjects were done and later subjected to PTA. The type and severity of hearing loss was noted. Occurrence of SNHL was later compared with age, sex, duration, and control of DM. Sensorineural hearing loss was found in 66 % of type II diabetic patients and 34 % were found normal. Out of 50 diabetes mellitus patients, 33 patients had SNHL. All cases of SNHL detected were of gradual in onset and no one had hearing loss of sudden onset. Normal hearing was found in 34 % of patients, whereas 54 % of patients had mild hearing loss and 12 % of patients had moderate hearing loss. Association of hearing loss of DM patients with sex of the patient is insignificant. However there is significant association between older age group, longer duration and uncontrolled DM with that of SNHL. In subjects with HbA1c more than 8 and duration of diabetes mellitus more than 10 years prevalence of SNHL is more than 85 %, which is statistically significant. Sensorineural hearing loss in diabetes mellitus is gradually progressive involving high frequency thresholds. Hearing threshold increases with increasing age duration of diabetes and also high level of HbA1c greater than 8 %.

Effect of Diabetes Mellitus on Hearing

“…1 Another study showed prevalence rate of 66%. 2 Diabetes and sensorineural hearing loss among non-elderly people was 45%. 3 Diabetes is usually classified as being of type 1 & type-2.…”

“…Diabetic neuropathies affect peripheral sensation & various autonomic functions. 2,4 The pathological changes that accompany diabetes may similarly cause injury to the vasculature or the neural system of the inner ear. So the pathogenic effects of diabetes on the ear can be grouped into neuropathic, angiopathic and a combination of the two.…”

“…Sorbitol accumulation is implicated in neuropathy by causing a decrease in myoinositol content, abnormal phosphoinositide metabolism & a decrease in Na+/k+ ATPase activity. 2 Histopathological evidence of vascular or neurological involvement obtained from autopsied patients with diabetes includes sclerosis of the internal auditory artery, thicker vessel walls of the stria vascularis & of the basilar membrane, demyelination of the cochlear nerve and atrophy of spiral ganglion. 5 Loss of outer hair cells has also been observed among patients with diabetes.…”

The clinical study of audiologic manifestations of type 2 diabetes mellitus in association with other diabetic microvascular complications: an observational study

“…Similar observation has been made by many other studies. 10,11 The occurrence of SNHL correlated with the levels of HbA1c among diabetics suggesting a possible significant association between diabetes and increased hearing loss as compared to the observation made by Kim MB et al in which they found that the risk of hearing loss increased progressively with increasing HbA1c levels above 5%. 10 5 individuals among cases had well controlled HbA1c (<5.6%), among whom only 1 had SNHL.…”

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

“…DM is one of the most common metabolic disorders, which is associated with hearing impairment [ 12 , 13 ]. Previous studies demonstrated that poorly controlled diabetics have significant hearing loss in high frequencies as compared with well controlled diabetes [ 12 , 14 , 15 ]. There is still a deal of controversy but, angiopathy and neuropathy have been considered important factors for the vestibular-cochlear disorders found in diabetic patients [ 16 ].…”