GLP-1 has been demonstrated to have pleiotropic, therapeutic effects on diabetes, such as modulating insulin secretion in a glucose-dependent manner, enhancing insulin sensitivity, suppressing glucagon secretion, promoting pancreatic β cell proliferation, aiding the restoration of normal β cell function, limiting food intake, inhibiting gastrointestinal motility, and decreasing postprandial glycemic excursions, without the risk of hypoglycemia; thus maintaining glucose homeostasis [5–9]. The gene discussed is GCG; the disease is diabetes mellitus.