Semaglutide is a long-acting GLP-1 (glucagon-like peptide-1) receptor agonist developed by Novo Nordisk, representing the current standard for single-mechanism metabolic peptide research. It mimics endogenous GLP-1 with 94% homology but with extended half-life (~165 hours) due to albumin binding via a C-18 fatty di-acid side chain. With extensive Phase 3 data across diabetes (SUSTAIN trials) and obesity (STEP trials), Semaglutide serves as a benchmark comparator for researchers studying newer metabolic peptides including Tirzepatide and Retatrutide.