The glucagon gene (GCG) encodes proglucagon, a precursor protein that is post-translationally processed into multiple bioactive peptides, including glucagon, glucagon-like peptide-1 (GLP-1), and GLP-2. GLP-1. primarily secreted by intestinal L-cells, plays a critical role in glucose homeostasis by stimulating insulin secretion, suppressing glucagon release, delaying gastric emptying, and promoting satiety. These actions make GLP-1 a key therapeutic target for type 2 diabetes and obesity. Antibodies targeting GCG-derived peptides, particularly GLP-1. are essential tools for research and diagnostics. They enable the detection and quantification of endogenous GLP-1 levels in biological samples, aiding studies on its secretion dynamics, receptor interactions, and metabolic effects. In drug development, GLP-1-specific antibodies are used to monitor pharmacokinetics of GLP-1 receptor agonists (e.g., exenatide, liraglutide) and to assess target engagement. Additionally, such antibodies help distinguish active GLP-1 forms (e.g., GLP-1(7-36)) from inactive metabolites, crucial for understanding physiological regulation. Challenges include ensuring specificity due to sequence homology among proglucagon-derived peptides and addressing GLP-1's short half-life. Overall, GCG/GLP-1 antibodies advance both basic research and clinical applications in metabolic disorders.