PTGFR and type 2 diabetes mellitus: To assess the role of the PGF2α/PTGFR axis in pathological retinal vascular proliferation, we quantified serum 15‐keto‐dihydro‐PGF2α in type 2 diabetic patients without diabetic retinopathy (no DR), with non‐proliferative diabetic retinopathy (NPDR), and with proliferative diabetic retinopathy (PDR).