In a study of the relationship between UCP2 polymorphisms and proliferative diabetic retinopathy (PDR), three UCP2 polymorphisms were selected (−866G/A (rs659366), Ala55Val (rs660339), and 45 bp insertion/deletion (Ins/Del)), and the haplotype [A Val Ins] was an independent risk factor for PDR in both types 1 and 2 diabetic groups [34]. Here, UCP2 is linked to proliferative diabetic retinopathy.