We observed increased C3a and C3aR expression with increased p-IKBα and IL-6 in the kidney of T2DM rat, as well as increased p-IKBα and IL-6 in C3a-treated HRGECs, suggesting that C3a induces IL-6 release via p-IKBα and NF-κB activation. This evidence concerns the gene C3 and type 2 diabetes mellitus.