In the present study, levels of the TGF‐β1 protein were significantly suppressed by C/EBPβ overexpression or the valsartan treatment, whereas diabetes and sh‐C/EBPβ exacerbated fibrosis in vitro and in vivo by up‐regulating TGF‐β1 expression, indicating that C/EBPβ overexpression reduces ECM deposition by decreasing Ang II‐induced TGF‐β1 expression. Here, TGFB1 is linked to diabetes mellitus.