Overview

GLP-1, short for glucagon-like peptide-1 is a short, naturally occurring peptide hormone just 30-31 amino acids in length. Its primary physiologic function is to lower blood sugar levels by naturally enhancing insulin secretion. It also plays roles in protection beta cell insulin stores by promoting insulin gene transcription and has been linked with neurotrophic effects in the brain and central nervous system. In the GI system, GLP-1 has been shown to significantly decrease appetite by delaying gastric emptying and reducing intestinal motility. Preliminary research has shown impacts of GLP-1 in the heart, fat, muscles, bones, liver, lungs, and kidneys as well.

The primary focus of GLP-1 research has been in diabetes treatment and prevention as well as appetite suppression. Secondary research focuses on the potential cardiovascular benefits of the peptide. More recent, and thus less robust, research focuses on the ability of GLP-1 to stave off neurodegenerative disease. Though this latter area of research is newest, it is also the fast-growing area of GLP-1 study now that the peptide has been revealed to slow or prevent the accumulation of amyloid beta plaques in the setting of Alzheimer’s disease.

Chemical Structure

Source: PubChem

Sequence: HXEGTFTSDVSSYLEGQAAK-OH.steric diacid-EFIAWLVRGRG
Molecular Formula: C187H291N45O59
Molecular Weight: 4113.58 g/mol
PubChem CID: 56843331
CAS Number: 910463-68-2
Synonyms: Semaglutide, Oxempic, Rybelsus, NN9535

From GLP-1 to Semaglutide

The overview above describes GLP-1, the natural hormone. Semaglutide is an engineered analog of it — about 94% identical to native GLP-1 by sequence — built to keep the hormone’s effects while lasting far longer in the body. Where natural GLP-1 is broken down within minutes, semaglutide persists for roughly a week, which is what allows once-weekly dosing in the subcutaneous formulations (Ozempic for type 2 diabetes, Wegovy for weight management) and once-daily dosing in the oral tablet (Rybelsus).

Mechanism of Action

Semaglutide activates the GLP-1 receptor. Receptor engagement increases insulin secretion only when blood glucose is elevated, suppresses inappropriate glucagon release, slows gastric emptying, and reduces appetite through hypothalamic and hindbrain pathways. Because the insulin effect is glucose-dependent, the peptide does not drive the low-blood-sugar episodes typical of insulin secretagogues — a property that made GLP-1 receptor agonists a backbone of modern type 2 diabetes and obesity research.

Structure and Stability

Three engineering changes explain semaglutide’s behavior. A substitution to alpha-aminoisobutyric acid at position 8 makes the peptide resistant to dipeptidyl peptidase-4. An arginine-to-lysine swap at position 34 creates a clean attachment point, and a C18 fatty-diacid chain linked through a short spacer binds strongly to serum albumin, shielding the molecule from enzymatic breakdown and kidney clearance. The result is a terminal half-life near 165 hours, which underpins once-weekly dosing. (Full sequence, molecular formula, molecular weight, and CAS number appear in the structure block above.)

Research Program and Key Findings

Semaglutide is one of the most thoroughly studied incretins, backed by large randomized programs. The SUSTAIN trials established glycemic benefit in type 2 diabetes; the STEP program showed mean weight loss near 15% of body weight over roughly 68 weeks on the weekly formulation; and the SELECT cardiovascular outcomes trial reported about a 20% reduction in major adverse cardiovascular events in people with overweight or obesity and established cardiovascular disease [3]. The oral version was evaluated in the PIONEER program. Outside metabolic disease, GLP-1 receptor agonists — semaglutide included — are under active investigation for neurodegenerative disease, consistent with the amyloid-beta and Alzheimer’s work noted in the overview; those studies remain early. For laboratory work the peptide is supplied lyophilized, reconstituted in bacteriostatic water or dilute acetic acid, aliquoted, and stored frozen; it is for in-vitro and analytical research only.

References

[1] Marso SP, et al. Semaglutide and cardiovascular outcomes in patients with type 2 diabetes (SUSTAIN-6). N Engl J Med. 2016.
[2] Wilding JPH, et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). N Engl J Med. 2021.
[3] Lincoff AM, et al. Semaglutide and cardiovascular outcomes in obesity without diabetes (SELECT). N Engl J Med. 2023.

Related Product: Semaglutide — for laboratory research use only.