To investigate whether patients with proliferative diabetic retinopathy (PDR) (Fig. 1A) show altered levels of interleukin-6 (IL-6) and its soluble IL-6 receptor (sIL-6R), vitreous humor and plasma samples from 17 PDR patients were compared to 17 patients with macular pucker (MP) and 19 patients with macular hole (MH), both serving as control groups (Fig. 1B) (Table 1). This evidence concerns the gene IL6R and proliferative diabetic retinopathy.