It was found that cytokine-cytokine receptor interaction, graft-versus-host disease, inflammatory bowel disease, lipid and atherosclerosis, human immunodeficiency virus type 1 infection, GnRH signaling pathway, sphingolipid signaling pathway, cell cycle, TNF signaling pathway, FOXO signaling pathway, etc. played an important role in T2DM. This evidence concerns the gene GNRH1 and graft versus host disease.