GLP-1 (7-37) vs Retatrutide

Binds GLP-1 receptors in the pancreas, gut, and brain. Stimulates glucose-dependent insulin secretion and suppresses glucagon. Central GLP-1 receptor activation reduces food intake via hypothalamic pathways.

GLP-1(7-37) is the native 30-amino-acid active form of glucagon-like peptide 1, an endogenous incretin hormone secreted by intestinal L-cells in response to nutrient ingestion, that acts at GLP-1 receptors throughout the body to stimulate glucose-dependent insulin secretion, suppress glucagon release, slow gastric emptying, reduce appetite, and protect beta-cell mass; it is the endogenous ligand underlying the pharmacology of the GLP-1 receptor agonist drug class. The GLP-1 receptor is expressed on pancreatic beta cells, hypothalamic appetite-regulating neurons, gastric enteric neurons, and cardiovascular tissue; GLP-1(7-37) activates cAMP/PKA signaling in beta cells to potentiate insulin release strictly during hyperglycemia, providing intrinsic hypoglycemia protection, and centrally reduces caloric intake through satiety signaling. A randomized controlled trial of continuous subcutaneous native GLP-1 infusion in patients with type 2 diabetes demonstrated significant reductions in plasma glucose and appetite, confirming receptor-mediated effects of the native peptide in humans; the peptide's very short plasma half-life of approximately 2 minutes due to rapid DPP-IV degradation makes continuous infusion the only practical administration route for the native form. Native GLP-1(7-37) has no FDA approval as a drug; FDA-approved GLP-1 receptor agonists — including semaglutide, liraglutide, dulaglutide, and tirzepatide — are chemically modified DPP-IV-resistant analogs developed to overcome the native peptide's pharmacokinetic limitations, and research-grade native GLP-1 is used exclusively as a tool compound in metabolic pharmacology studies.

Triple GIP/GLP-1/glucagon receptor agonist; targets three pathways for synergistic fat reduction

Retatrutide (LY3437943) is an investigational triple hormone receptor agonist that simultaneously activates GLP-1, GIP (glucose-dependent insulinotropic polypeptide), and glucagon receptors, combining the complementary metabolic actions of all three incretin and counterregulatory hormone pathways in a single weekly injection. The GLP-1 component drives satiety and insulin secretion, GIP enhances adipose lipid metabolism and further modulates appetite, and glucagon receptor activation increases energy expenditure — together producing greater weight loss than single or dual agonists in the same receptor class. A Phase 2 randomized controlled trial published in the New England Journal of Medicine demonstrated dose-dependent weight reductions of up to 24% of body weight at 48 weeks, among the largest reported for any pharmacological obesity treatment. Retatrutide has not received FDA approval; it is under Phase 3 registrational evaluation (TRIUMPH trials) as of 2025 for obesity, obstructive sleep apnea, and knee osteoarthritis. Retatrutide cost and access As of mid-2026, retatrutide has not received FDA approval and is not commercially available as a branded pharmaceutical. It is in late-stage (Phase 3) clinical development through Eli Lilly. Access pathways include: enrollment in active clinical trials (listed on ClinicalTrials.gov), research-use peptide vendors who supply retatrutide for laboratory/research contexts (not for human use), and a limited number of compounding pharmacies that compound investigational or pre-approval compounds under provider-supervised protocols. Cost per month of research-grade retatrutide from vendors varies considerably by quantity and formulation. Branded pharmaceutical pricing will be established at approval; given tirzepatide's pricing trajectory and the triple-agonist mechanism, analyst forecasts suggest a premium pricing position relative to existing GLP-1 agonists. Retatrutide vs survodutide: Survodutide (BI 456906, Boehringer Ingelheim + Zealand Pharma) is a dual GLP-1 and glucagon receptor agonist in Phase 3 development for MASH (metabolic dysfunction-associated steatohepatitis) and obesity. Compared to retatrutide, survodutide lacks the GIP receptor component; retatrutide's triple agonism adds GIP-mediated adipose lipid oxidation to the GLP-1 + glucagon combination. In trial comparisons, both compounds show substantial weight reductions (retatrutide 24.2% at 12mg/week in Phase 2; survodutide 18.7% at highest dose in Phase 2). Neither compound has a direct head-to-head trial yet. Both represent the next tier beyond tirzepatide in the GLP-1 + additional agonism category. Retatrutide's MASH indication (liver fat reduction) also overlaps with survodutide's primary development focus. The competitive landscape in this category is evolving rapidly as multiple Phase 3 readouts are expected through 2026–2027.