Additionally, the T149M variant is associated with increased T2D risk and has normal surface expression but reduced binding affinity for GLP-1 and Exenatide, as well as reduced cAMP production (Beinborn et al., 2005), although a study was able to rescue both cAMP and ERK1/2 signalling for this variant using the allosteric modulator Compound 2 (Koole et al., 2011). Here, GCG is linked to type 2 diabetes mellitus.