FGF21 and type 1 diabetes mellitus: Therefore, FF protects against T1D-induced DN via a PPARα-mediated increase in FGF21, which activates Akt2/GSK-3β/Fyn/Nrf2 signaling to upregulate the Nrf2-mediated antioxidant mechanism, but also via activation of AMPK, which mediates an amelioration of the metabolic defects.