LEP and non-proliferative diabetic retinopathy: Similarly, plasma concentrations of APN, leptin, and FABP4 were more elevated in the patients with STDR (23.60 μg/ml, 13.69 ng/ml, and 29.77 ng/ml) than in the mild NPDR group (21.13 μg/ml, 11.84 ng/ml, and 24.38 ng/ml, respectively) in the testing set.