A report [46] has found that the levels of TNF-α and IL-6 in the diabetes group were significantly higher than those of the normal group at the 2th week after induction, while another study [47] has suggested that IL-6 and TNF-α became significantly elevated in diabetic retina after STZ injection as compared with normal rats at the 4th week after induction and continued to the 8th week. Here, TNF is linked to diabetes mellitus.