Background: Diabetes mellitus (DM) causes both micro- and macrovascular complications. The cochlea and auditory nerves are therefore at increased risk from DM-related complications due to microangiopathy, neuropathy or mitochondrial damage. Limited data are available from Africa detailing the association between DM and hearing impairment (HI).
Objectives: To describe the prevalence and spectrum of and associations with HI in patients living with DM (PLWD) with and without HIV infection.
Methods: This was an analytical cross-sectional study conducted between 1 October and 31 December 2019 at the Edendale Hospital diabetes and audiology clinics in Pietermaritzburg, South Africa. PLWD had an audiological assessment using pure-tone audiometry together with a questionnaire enquiring about tinnitus, vertigo, dizziness and HI.
Results: A total of 296 PLWD (89.2% with type 2 DM) were enrolled, of whom 154 (52.0%) had HI. Type 2 PLWD had a significantly higher prevalence of reported symptoms and confirmed audiological HI, which was most often bilateral. The most frequent HI categories were mild to moderate, mild, and moderate to severe (33.8% v. 25.9% v. 23.9%, respectively). Significant associations were noted between dizziness (p=0.045), reported hearing loss (p<0.001) and objective evidence of HI (all categories except mild). HI was significantly associated with age >50 years, DM duration ≤10 years, female gender, hypertension, increased low-density lipoprotein and total cholesterol (TC), lower high-density lipoprotein cholesterol, suboptimal glycaemic control, non-proliferative retinopathy, sensory neuropathy and obesity (p<0.05). Approximately half (48.9%) of PLWD and HIV infection had HI, and they were significantly younger and had higher TC levels than PLWD without HIV (p<0.05).
Conclusions: We showed that HI occurs in over half of PLWD, usually within the first 10 years after diagnosis of DM. Symptoms of HI were shown to have positive associations with all HI categories except mild. A high level of vigilance for HI must be maintained in PLWD.