The results show that treatment with FGF21 can protect cardiac mitochondria in T1D mice from oxidative damage as indicated by a significantly increased GSH (Fig. 6k) and decreased MDA (Fig. 6l), but these beneficial effects of FGF21 were significantly restrained in the heart of T1D mice after LAT1 overexpression. Here, FGF21 is linked to type 1 diabetes mellitus.