Dietary intake of retinol (p<0.05) and retinol equivalent (p<0.05) was significantly lower, and serum retinol and (p<0.01) retinol binding protein 4 (RBP4) (p<0.01) were significantly higher in DRG compared with DNRG.
For each 1 μg/ml increase in plasma level of RBP4, the unadjusted and adjusted risk of DR would be increased by 8% (with the odds ratio (OR) of 1.08 (95% CI: 1.05-1.13), <i>P</i><0.001) and 5% (1.05 (1.02-1.11), <i>P</i>=0.001), respectively.
Elevation of serum retinol-binding protein 4 (RBP4) induces inflammation in primary human retinal microvascular endothelial cells (HRECs) via a retinol-independent mechanism; thus, it may play a causative role in the development and progression of vascular lesions in diabetic retinopathy (DR).