Association of insulin resistance with visual decline in older individuals without diabetes: a cross-sectional mediation analysis

AIMS: It remains unknown how visual decline affects insulin resistance in individuals without diabetes. Therefore, we investigated the association between visual impairment and insulin resistance in older individuals without diabetes. METHODS: Data from the Kyotango Longevity Cohort Study, a prospective investigation encompassing adults aged 65 years and above, were included. The study protocol was approved by the Ethics Committee of the Kyoto Prefectural University of Medicine (ERB-C-885). Visual acuity and insulin resistance were assessed using logarithmic minimum angle of resolution (logMAR) and homeostasis model assessment ratio (HOMA-R), respectively. The correlation between logMAR and HOMA-R was examined using Spearman's rank correlation coefficient and multiple regression analysis. Causal mediation analysis was performed with body composition as a mediating factor. RESULTS: In total, 797 participants were enrolled. Mean age was 74.8 ± 6.6 years in men and 73.4 ± 5.6 in women. logMAR and HOMA-R were correlated in women without diabetes after adjustment for covariates (β = 0.166, P = 0.0002). Causal mediation analysis revealed that body fat mass (proportion mediated: 0.567, 95% CI: 0.058-0.938) and body fat percentage (proportion mediated: 0.685, 95% CI: 0.250-1.027) significantly mediated the relationship between logMAR and HOMA-R in women. CONCLUSIONS: Vision decline was associated with insulin resistance, with body fat statistically accounting for part of this association.