GLP-1 (7-37) vs Liraglutide

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.

GLP-1 receptor agonist; slows gastric emptying, increases satiety, reduces glucagon secretion

Liraglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist approved for chronic weight management and type 2 diabetes, formulated as a daily subcutaneous injection that reduces appetite by activating GLP-1 receptors in the hypothalamus and brainstem. It mimics endogenous incretin hormone action — slowing gastric emptying, increasing satiety signaling, and reducing caloric intake through central and peripheral GLP-1 receptor pathways. The landmark SCALE Obesity trial, a large multicenter randomized controlled trial published in the New England Journal of Medicine, demonstrated significant weight loss of approximately 8% at 56 weeks with 3.0 mg liraglutide (Saxenda) compared to placebo. Liraglutide is an FDA-approved prescription medication available as Victoza (type 2 diabetes, 1.8 mg) and Saxenda (chronic weight management, 3.0 mg); it requires physician supervision and is contraindicated in patients with a personal or family history of medullary thyroid carcinoma. Liraglutide vs semaglutide: key distinctions Liraglutide is a daily subcutaneous injection; semaglutide is weekly. The dosing frequency difference reflects half-life: liraglutide's plasma half-life is approximately 13 hours, requiring daily administration to maintain therapeutic levels; semaglutide's albumin-binding modification extends its half-life to approximately 7 days. For weight management outcomes, semaglutide significantly outperforms liraglutide: STEP 1 reported ~15% mean weight reduction vs ~8% with liraglutide in SCALE. The practical implication is that liraglutide is generally appropriate for patients who have contraindications to once-weekly GLP-1 therapy, who are already established on liraglutide for T2D (Victoza), or who are in a jurisdiction where semaglutide is less accessible. Liraglutide has a longer post-approval safety record — it was approved in 2010 for T2D and 2014 for obesity management — while semaglutide's obesity indication was approved in 2021. The LEADER trial established cardiovascular risk reduction for liraglutide in T2D patients, adding an outcomes benefit beyond glucose control. Liraglutide cost and access: As a branded pharmaceutical (Victoza, Saxenda), liraglutide requires a prescription from a licensed provider. Saxenda (3.0mg/day for obesity) has an approximate monthly list price of $1,300–$1,500 USD; actual cost varies by insurance coverage and assistance programs. Generic or biosimilar liraglutide is not yet widely available in the US market. Compounding pharmacies do not commonly produce liraglutide formulations given the availability of approved branded products. Providers offering GLP-1 agonist programs that include liraglutide are searchable in the PeptideBase provider directory.