Growing insight into the contribution of glucagon to the pathogenesis of diabetes as well as further characterization of regulatory mechanisms for glucagon secretion invigorated this field of research (Leiss et al., 2011; Zhang et al., 2013; Gàlikovà et al., 2015; Palu et al., 2017; Song et al., 2017; Braco et al., 2020; Kellard et al., 2020). This evidence concerns the gene GCG and diabetes mellitus.