Exendin-4, an agonistic polypeptide for human GLP-1R derived from the venom of the Gila monster lizard, has also been shown to enhance lysosomal function in β-cells, improve autophagosome clearance and protect against islet injury in a rat model of tacrolimus-induced diabetes (Lim et al., 2016). This evidence concerns the gene GLP1R and diabetes mellitus.