Numerous studies have shown that MMP-9 is a key pathological mediator in renal fibrosis of DN, involved in the degradation of ECM components such as type I collagen (Col-I), and type III collagen (Col-III), disrupting the dynamic balance of ECM degradation and deposition, thus regulating the progression of fibrosis (13). The gene discussed is MMP9; the disease is renal fibrosis.