Owing to its attractive biological functions such as stimulation of insulin secretion in a glucose-dependent fashion, inhibiting glucagon release, suppressing appetite and slowing gastric emptying, GLP-1 is currently used as a major type of incretin-based therapy for type 2 diabetes (T2D) (Nauck et al., 1993; Wettergren et al., 1993). The gene discussed is GCG; the disease is type 2 diabetes mellitus.