Exploring Middle Ear Pathologies in Adults with Diabetes Mellitus: A Scoping Review of Available Evidence and Research Gaps

Diabetes mellitus (DM) is a common chronic health condition, affecting millions of people worldwide, and its incidence is projected to increase by almost 50% in the next two decades. The effects of DM on the auditory system have been reported. However, there is limited evidence on the association between DM and middle ear pathologies. This scoping review aimed to map the available evidence and identify research gaps regarding DM and middle ear pathologies in the adult population. Five electronic databases, namely Scopus, CINAHL, MEDLINE, PubMed, and Web of Science, were searched using a combination of specific key terms. This review followed the guidelines stipulated by the Joanna Briggs Institute (JBI) methodology for scoping reviews and reporting using PRISMA Extension for Scoping Reviews (PRISMA-ScR): checklist and explanation. A thematic narrative analysis was used to synthesize key findings. Of the 1809 articles, only 2 articles met the inclusion criteria. Neither of these studies focused exclusively on middle ear pathologies in DM, but they did report incidental findings related to middle ear function. Available evidence suggests that middle ear pathologies may occur in individuals with DM, with a reported prevalence ranging from 3.1% to 19.6%. Otitis media with effusion and conductive hearing loss were common middle ear pathologies identified. Additionally, recent studies have provided new evidence suggesting ossicular joint changes in individuals with DM and a causal link between DM and acute suppurative otitis media. However, age-related hearing loss (presbycusis) and sensorineural hearing loss (SNHL) were more commonly associated with DM, with studies reporting a high prevalence of SNHL in younger to middle-aged adults with diabetes. This review highlights a significant research gap in the literature, as no studies directly investigated the relationship between DM and middle ear function as a primary focus. Further research is required to investigate this potential association using methodologies explicitly designed for middle ear assessment. While some evidence suggests a possible association, the lack of age-stratified analyses, imaging data, and comprehensive diagnostic testing limits the ability to draw strong conclusions. Further research incorporating age-based analyses, radiological assessments, and microbiome studies is needed to fully understand the potential impact of DM on middle ear health.