Diabetes induced an obvious decrease in the TNFSF15 protein level in the retina of rats to 14.8% ± 3.4% and 72.6% ± 9.9% in the DM1 and DM3 groups compared with that of the control group, respectively (F = 57.738, p < 0.001). This evidence concerns the gene TNFSF15 and diabetes mellitus.