FGF21 is a hormone with roles in glucose and lipid metabolism (Kharitonenkov et al., 2005) and plays a survival role in response to diverse stressful conditions, such as amino acid deprivation, mitochondrial stress and ER stress-associated diseases such as diabetes, cardiovascular diseases (reviewed in [Gómez-Sámano et al., 2017; Kim and Lee, 2015; Salminen et al., 2017]). Here, FGF21 is linked to diabetes mellitus.