Fig. 2.

The relationship between RC levels and DR, stages of DR, and DME. Abbreviations: DR: diabetic retinopathy; NPDR: non-proliferative diabetic retinopathy; PDR: proliferative diabetic retinopathy; DME: diabetic macular edema. Notes: The RC level was divided into three groups by tertile, Tertile1 group (< 0.52 mmol/l, N = 150), Tertile2 group (0.52–0.83mmo/l, N = 152) and Tertile3 group (> 0.83 mmol/l, N = 154). Chi-square test was used for comparison between groups, *P < 0.05, **P < 0. 01