Abstract: Objective To investigate the relationship between the levels of serum mononuclear nuclear factor E2 associated factor (Nrf2) and Kelch-like ECH associated protein 1 (Keap1) and diabetic retinopathy (DR) staging. Methods A total of 147 DR patients who were admitted to Rugao Traditional Chinese Medicine Hospital from April 2020 to February 2023 were selected as an observation group. According to DR staging, they were divided into two types:non-proliferative diabetic retinopathy (NPDR) and proliferative diabetic retinopathy (PDR). Meanwhile, 49 diabetic patients without retinopathy were selected as a control Ⅰ group, and 49 healthy patients were selected as a control Ⅱ group. These groups were compared for the levels of serum Nrf2 and Keap1. The relationship between serum Nrf2 and Keap1 levels and DR staging was analyzed by Spearman rank correlation coefficient. The effect of serum Nrf2 and Keap1 levels on DR staging was analyzed by multivariate logistic regression. The dose-effect relationship between serum Nrf2 and Keap1 levels and DR staging was analyzed by restricted cubic spline diagram. Results The observation group showed lower levels of serum Nrf2 but higher levels of serum Keap1 than the control Ⅰ and Ⅱ groups, while the control Ⅰ group presented lower levels of serum Nrf2 but higher levels of serum Keap1 than control Ⅱ group (P<0.05). With the increase of DR stages, serum Nrf2 levels decreased, but serum Keap1 levels increased (P<0.05). Serum Nrf2 levels were negatively correlated with DR staging (r=-0.806, P<0.001), while serum Keap1 levels were positively correlated with DR staging (r=0.854, P<0.001). According to multiple logistic regression analysis, hypertension, diabetes onset age and total cholesterol exerted no significant effect on DR staging (P>0.05). Serum Nrf2 level was an independent protective factor for DR staging, while hyperlipidemia, diabetes course, fasting blood glucose, glycosylated hemoglobin and serum Keap1 level were independent risk factors for DR staging (P<0.05). Restricted cubic spline analysis indicated a nonlinear relationship between serum Nrf2 (χ²=11.800, P<0.001), Keap1 (χ²=8.401, P=0.015) levels and DR staging; the risk of PDR significantly increased when other diseases were controlled as fixed variables, while serum Nrf2 levels were lower than 1.70 μg/L and serum Keap1 levels were higher than 3.00 μg/L. Conclusions Serum Nrf2 and Keap1 levels are closely related to DR staging. Serum Nrf2 level < 1.70 μg/L and serum Keap1 level > 3.00 μg/L suggest a significantly increased risk of progression from DR to PDR.