MMP9 and diabetes mellitus: To summarize, hyperglycemia triggers accumulation of M1 macrophages along with elevated pro-inflammatory cytokine, chemokine and pro-fibrotic factors (TNF-α, IL-1β, MCP-1 and TGF-β1), that may be contributing to the increased α-SMA and decreased E-cadherin expression indicating EMT, and elevated levels of MMP-9 and MMP-13 expression in the diabetic kidney.