Association between subtypes of diabetes and special sensations: A 2-sample Mendelian randomization study

Diabetes, a chronic condition affecting millions of individuals, is divided into type 1 diabetes (T1D) and type 2 diabetes (T2D), each with unique pathophysiological characteristics. While the impact of diabetes on vision is established, its relationship with other special senses, balance, hearing, and olfaction, remains uncertain. This study utilized a 2-sample Mendelian randomization (MR) approach to investigate the associations between diabetes subtypes and specific sensory disorders. We performed MR analysis using various methods (inverse variance weighting [IVW], MR-Egger, simple mode, weighted mode, weighted median, MR-PRESSO) to assess the causal relationships between diabetes subtypes and sensory disorders (vestibular dysfunction, sensorineural hearing loss, conductive hearing loss, and olfactory dysfunction). Different diabetes genome-wide association studies datasets were utilized for validation. MR analysis revealed no significant correlations between T1D or T2D and the sensory disorders studied. Interestingly, an initial signal suggested that T1D might increase the risk of conductive hearing loss (IVW: odds ratio = 1.120, 95% CI: 1.035-1.211, P = .005), but this finding was not supported by validation studies. No evidence of horizontal pleiotropy or heterogeneity was found (P > .05). Our MR analysis and subsequent validation revealed no significant associations between diabetes subtypes and special senses. The initial suggestion of an increased risk of conductive hearing loss in T1D patients was not confirmed. Future research should further explore the intricate relationships among diabetes, sensory functions, and other factors, as well as the potential effects of diabetes management on sensory health.