Under the condition of diabetic retinopathy, due to the increase of mitochondrial reactive oxygen species caused by hyperglycemia, the expression of cell adhesion molecules (ICAM-1, VCAM-1) is upregulated under the action of interleukin (IL-1, IL-6) induced by reactive oxygen species, and leukocyte adhesion damages endothelial cells. This evidence concerns the gene ICAM1 and diabetic retinopathy.