Jie Yin ^* Juan Chen Yuanyuan Chen

• Affiliated Hospital of Hangzhou Normal University, Hangzhou, China

Aim: To explore the association between the ratio of 4-pyridoxine (4-PA) to pyridoxal 5'-phosphate (PLP) (4-PA/PLP) and diabetic retinopathy (DR), and further assess the mediating effect of Endothelial Activation and Stress Index (EASIX) on the association between 4-PA/PLP and DR.In this cross-sectional study, 1698 patients with diabetes from National Health and Nutrition Examination Survey were included. According to the median, 4-PA/PLP was categorized into high-level group (≥0.89) and low-level group (<0.89). As the EASIX had a skewed distribution, it was log transformed before analysis. Weighted logistic regression models were used to investigate the association of 4-PA/PLP with EASIX and DR, and the mediating effect of EASIX on the association between 4-PA/PLP and DR. Distribution-of-product method was adopted to assess the mediating effect. Subgroup analysis was performed based on age and duration of diabetes.Results: 362 patients with diabetes were classified as having DR. After adjusting for all covariates, high level 4-PA/PLP was found to be related to an increased levels of log EASIX [odds ratio (OR)=1.56, 95% confidence interval (CI): 1.06-2.30]. High level 4-PA/PLP was associated with an increased odd of DR compared to the reference group with low levels of 4-PA/PLP (OR=1.94, 95%CI: 1.40-2.67). Additionally, we found that log EASIX may play a mediating role in the 4-PA/PLP and DR, with a 95% CI of distribution-of-product of 0.31 (95% CI: 0.02-0.67). The proportion of mediation was 69.06%. The mediating effect of log EASIX was also observed in individuals with diabetes who aged≥60 years (proportion of mediation: 50.63%) or had duration of diabetes ≥10 years (proportion of mediation: 71.83%).This study revealed a positive association between high level of 4-PA/PLP and increased risk of DR, with the relationship partially mediated by log EASIX.