Authors: Camille Rochmann¹, Zoe Kaier-Green¹, Blandine Duval¹, Hugo Laullier¹, Laura Breda¹, Mathieu Schué¹
¹CILCARE SAS
Background: Sensorineural hearing loss related to diabetes is increasingly documented, with possible causes including cochlear microangiopathy, chronic inflammation, or peripheral auditory neuropathy. These factors may contribute to speech-in-noise intelligibility deficit despite normal standard audiograms, often reported as “hidden hearing loss”.
Method: DIAMANT was a French, multicenter, cross-sectional, prospective study conducted in France to evaluate the prevalence of various auditory dysfunctions in uncontrolled type-2 diabetes (T2D) patients. Participants who consented (aged 25–70, T2D >2 years, HbA1c >7%) underwent a comprehensive battery of tests: tonal (0.25-16 kHz) audiometry, vocal audiometry in silence and in noise (French Matrix test (Framatrix)), Distortion Product OtoAcoustic Emissions, electrocochleography (EcochG), and cognitive screening via the Montreal Cognitive Assessment (MoCA). Participants with abnormal otoscopy, tympanometry, conductive / asymmetrical hearing loss were excluded.
Results: Among 241 participants (61% women, median age 60 [IQR:53.0-64.0]), three hearing profiles emerged.After excluding those with cognitive impairment (MoCA <26), 137 participants remained: 59.8% Normal hearing, 26.3% SIN-D, and 13.9% HL.
NH and SIN-D had similar thresholds at low frequencies (0.25–1 kHz), but SIN-D diverged at mid-to-high frequencies (≥2 kHz), resembling HL at 8-16 kHz. At group level, EcochG revealed significantly reduced auditory nerve response to suprathreshold stimulations in SIN-D compared to NH, reflecting a decrease or degeneration of synapses and/or spiral ganglion cells.
Conclusion: Although SNHL prevalence in T2D was not higher than in the general population, SIN deficit with normal hearing was more frequent. SIN testing offers a practical, non-invasive alternative to electrophysiology and should be integrated into routine auditory testing. More work should confirm SIN testing as a biomarker of peripheral auditory neuropathy.
