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PeptideHormone

Semaglutide

A long-acting GLP-1 receptor agonist engineered for once-weekly dosing.

Also known as Ozempic, Wegovy, Rybelsus.

AnalogEstablishedBased on Glucagon-like peptide-1Compare with GLP-1 Compare lineage

The same sentence the gut speaks, rewritten to last a week instead of two minutes — and the clearest demonstration of what peptide engineering can now do.

Identity

Class
GLP-1 receptor agonist (acylated peptide, 31 aa)
Source
Synthetic analog of human GLP-1
Receptor
GLP-1 receptor (GLP-1R)

Key properties

Evidence floorClinicalREF1CLIN1
Molecular weight
~4,113.6 Da
REF
Half-life (native)
~7 days (~165 h)
CLIN
Model dosing

Approximate values for the native hormone; engineered analogs are often deliberately larger and far longer-acting. Each figure carries its own provenance tier, and the floor is the weakest of them - the Standard.

Mechanism

Semaglutide is a GLP-1 analog modified to resist DPP-4 and to bind albumin via a C18 fatty-diacid chain, stretching its half-life from GLP-1's ~2 minutes to roughly a week. At the receptor it is the same molecule as native GLP-1 — driving glucose-dependent insulin secretion, slowed gastric emptying, and central satiety. The engineering is entirely about durability and delivery, not a new mechanism.

GIPRadded by tirzepatideGCGRadded by retatrutideSemaglutideone peptideGLP-1RSatiety · insulin
One peptide, one receptor — the single note. Everything else on this page is engineering to make that note last: the GIP and glucagon slots stay empty until the co-agonists arrive.

In depth

Semaglutide is the single note the whole metabolic chord is built out from. At the receptor it is not a new molecule — it drives the same GLP-1 biology as the hormone your gut releases after a meal: glucose-dependent insulin, slowed gastric emptying, central satiety. What makes it a drug rather than a curiosity is durability. Native GLP-1 is gone in about two minutes; semaglutide lasts about a week.

That week is bought by engineering, not biology. Two amino-acid substitutions shield the peptide from DPP-4, the enzyme that clears the native hormone, and a long fatty-diacid chain latches it onto circulating albumin so the kidney cannot flush it quickly. The result is a molecule that holds a steady signal from a single weekly dose — the delivery problem solved, the mechanism left untouched. An oral form clears the stomach with an absorption enhancer, trading a needle for a strict empty-stomach ritual.

The clinical readouts are what turned a good diabetes drug into a cultural event: mid-teens percentage weight loss in STEP-1, then a cardiovascular-event reduction in SELECT that pointed past the scale. Semaglutide proved how far one well-delivered incretin note could go — which is exactly what set the field asking whether a second note (tirzepatide) or a third (retatrutide) could go further still. The empty GIP and glucagon slots in the figure above are the sequel the co-agonists were written to answer.

Reference notes

  • Two amino-acid substitutions plus fatty-acid acylation give albumin binding and DPP-4 resistance — the basis of weekly dosing.
  • Approved for type 2 diabetes (Ozempic, 2017; oral Rybelsus, 2019) and chronic weight management (Wegovy, 2021).
  • In the STEP-1 obesity trial the weekly injection cut body weight by roughly 15% at 68 weeks — the result that reset expectations for the whole class.
  • SELECT showed a cardiovascular-event reduction in people with obesity and established heart disease — evidence the benefit reaches past weight and glucose.
  • Mechanistically identical at the receptor to native GLP-1 — see the GLP-1 reference for the underlying cascade.

Common questions

What is Semaglutide?
A long-acting GLP-1 receptor agonist engineered for once-weekly dosing. Structurally it is GLP-1 receptor agonist (acylated peptide, 31 aa).
How does Semaglutide work?
Semaglutide is a GLP-1 analog modified to resist DPP-4 and to bind albumin via a C18 fatty-diacid chain, stretching its half-life from GLP-1's ~2 minutes to roughly a week. At the receptor it is the same molecule as native GLP-1 — driving glucose-dependent insulin secretion, slowed gastric emptying, and central satiety. The engineering is entirely about durability and delivery, not a new mechanism.
How strong is the evidence for Semaglutide?
PeptideHormone grades Semaglutide at the "Established" evidence tier — its mechanism and core effects are settled across the peer-reviewed literature. It is catalogued as an engineered analog built on an endogenous hormone, and the tier is an editorial judgment about the public literature that can change as the science does.
What is the half-life of Semaglutide?
The reported circulating half-life of Semaglutide is ~7 days (~165 h).
Is Semaglutide the same as Ozempic, Wegovy, or Rybelsus?
Ozempic, Wegovy, and Rybelsus are brand names of Semaglutide — the same molecule in different approved presentations. This page is the molecule reference, not a prescribing guide.

Selected literature

Curated peer-reviewed reviews, sourced from PubMed. Selected for relevance, not exhaustive — open any entry on PubMed for the full record and its primary citations.

  1. 1.Efficacy and Safety of Semaglutide for Weight Loss in Obesity Without Diabetes: A Systematic Review and Meta-Analysis · Journal of the ASEAN Federation of Endocrine Societies, 2022 · PMID 36578889
  2. 2.The Discovery and Development of Liraglutide and Semaglutide · Frontiers in endocrinology, 2019 · PMID 31031702

External references

Semaglutide in the public knowledge graph — the same entity resolved across the authoritative chemistry and protein databases.