The impact of vestibular dysfunction on falls and postural instability in individuals with type 2 diabetes with and without diabetic polyneuropathy

Aim. This study aimed to determine the association between vestibular dysfunction, falls, and postural instability in individuals with type 2 diabetes (T2D) compared to healthy control individuals and to examine the impact of diabetic polyneuropathy (DPN). Methods. This cross-sectional study included individuals with T2D with DPN (n = 43), without DPN (n = 32), and healthy controls (n = 32). Cervical and ocular vestibular evoked myogenic potentials (VEMP) were recorded, and latencies and amplitudes were determined. DPN was diagnosed based on nerve conduction studies and clinical scores. Postural instability was examined using a static posturographic balance system and calculated as an instability index (ST). Falls were recorded retrospectively during the past year. Group comparisons were conducted by using univariate and bivariate statistics. Results. Individuals with T2D experienced more falls than healthy controls (T2D with DPN n = 12[38%], T2D without DPN n = 15[35%], controls n = 5[16%], p = 0.04). Individuals with T2D had decreased postural stability, T2D with DPN, ST (median of 52[iqi = 33; 77]), T2D without DPN, ST (median of 31[iqi = 24; 39]), controls ST (median of 26[iqi = 19; 33], p = 0.01), when comparing all three groups. Individuals with T2D had a greater number of no-responses in oVEMP compared to controls (T2D with DPN, n = 15[46.9%] T2D without DPN n = 25[58.1%], controls n = 9[28.1%], p = 0.04). No difference was found in cVEMP and oVEMP amplitudes in any of the groups. Irrespectively of DPN, fallers with T2D had decreased oVEMP and cVEMP latencies on the right ears, when comparing to non-fallers, respectively, n10 (fallers [median of 16, iqi=15;19 ms.] vs. non-fallers [median of 25 iqi=16;35 ms]); p13 (fallers [median of 16, iqi=15;17 ms.] vs. non-fallers [median of 15, iqi=8;16 ms.], p < 0.05). Conclusion. Falls and postural instability were more frequent in individuals with T2D compared to healthy controls. Fallers with T2D had vestibular end-organ impairments based on the oVEMP and cVEMP latencies on the right but not the left ears, irrespective of DPN. Individuals with T2D had more frequent no-response of the oVEMP, indicating impaired vestibular nerve function.