In the present study, our data also indicate that serum FGF21 levels are significantly associated with insulin, HOMA-IR index, or macrovascular disease in NPDR and PDR subjects, suggesting that elevated FGF21 levels are closely related to the injury of capillary and the change of retinal function in diabetic retinopathy patients. Here, FGF21 is linked to non-proliferative diabetic retinopathy.