FGF21 and diabetes mellitus: In agreement with the previous studies, induction of diabetes increased circulating levels of VEGF, FGF21, and TGF-β and decreased plasma concentrations of FLK-1 and sFLT-1 in STZ-treated rats.19,20 In addition to the effect on its secreted tissue as a paracrine factor, VEGF enters circulation and can exert its effects on other tissues that express high levels of its receptors.