For research purposes only. Not for human use. Semaglutide is an FDA-approved medicine when dispensed as Ozempic, Wegovy or Rybelsus; research-grade semaglutide sold to laboratories is not that product. Nothing here is medical advice or an administration protocol.
What Semaglutide Is
Semaglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist developed by Novo Nordisk as a once-weekly successor to the once-daily liraglutide. Compared with native human GLP-1 it carries two amino-acid substitutions (Aib8 and Arg34) and a C18 diacid fatty-acid chain attached through a spacer at lysine 26. The substitution at position 8 protects against cleavage by dipeptidyl peptidase-4; the fatty-acid chain gives high-affinity, reversible binding to serum albumin, which is what stretches the half-life to about a week.
The discovery paper reports that semaglutide's GLP-1 receptor affinity (0.38 nM) is about three-fold weaker than liraglutide's, while albumin affinity is higher; the plasma half-life in mini-pigs was 46.1 hours after intravenous administration (Lau et al., 2015). In humans the elimination half-life is roughly one week for both the subcutaneous and oral products, with steady state reached after four to five weeks of weekly dosing (Drug Design, Development and Therapy, 2024).
It is the most thoroughly studied peptide on this site: two large phase 3 programmes (SUSTAIN in type 2 diabetes, STEP in obesity), three cardiovascular outcome trials, a kidney outcome trial and a liver histology trial. This overview summarises what those trials measured, then reports what the research-chemical market for the molecule looks like from platform data.
Mechanism
GLP-1 is an incretin hormone released from intestinal L-cells after eating. Its receptor is a class B G-protein-coupled receptor expressed on pancreatic beta cells, in the gastric wall, on vagal afferents and in hypothalamic and hindbrain regions that regulate appetite. Receptor activation raises cyclic AMP; in beta cells that amplifies glucose-stimulated insulin secretion (so insulin release rises only when glucose is elevated), and in alpha cells it suppresses glucagon release.
GLP-1 receptor agonists also slow gastric emptying, which flattens post-meal glucose excursions but also raises the question of retained gastric contents before procedures; a 2024 review in The Lancet Gastroenterology & Hepatology describes the evidence as thin for long-acting agents and proposes pre-procedural management pathways (Jalleh et al., 2024). The weight-loss effect is predominantly central: reduced appetite and food intake through hypothalamic and brainstem circuits rather than a change in energy expenditure (Mol Metab, 2022).
Type 2 Diabetes: The SUSTAIN Programme
SUSTAIN 6 was the cardiovascular safety trial required by regulators. It randomised 3,297 patients with type 2 diabetes at high cardiovascular risk to once-weekly semaglutide (0.5 mg or 1.0 mg) or placebo for 104 weeks. The primary composite of cardiovascular death, non-fatal myocardial infarction or non-fatal stroke occurred in 6.6% of the semaglutide group and 8.9% of the placebo group (hazard ratio 0.74), driven mainly by fewer non-fatal strokes (1.6% vs 2.7%). The trial was designed to show non-inferiority and the confidence interval also excluded harm (Marso et al., 2016).
SUSTAIN 7 compared semaglutide head-to-head with dulaglutide in 1,201 patients on metformin. At both the low and high dose pairings semaglutide produced larger reductions in HbA1c and body weight, with a similar safety profile and gastrointestinal events the most common reason for discontinuation in both arms (Pratley et al., 2018).
The oral formulation, co-formulated with the absorption enhancer SNAC, was tested in the PIONEER programme. In PIONEER 1, oral semaglutide monotherapy improved HbA1c at all three doses and body weight at the highest dose versus placebo over 26 weeks, with transient gastrointestinal events the most common adverse event (Aroda et al., 2019).
Obesity: STEP 1 and What Happens After Stopping
STEP 1 enrolled 1,961 adults with a BMI of 30 or more (or 27 with a weight-related condition) and no diabetes, randomised 2:1 to once-weekly semaglutide 2.4 mg or placebo alongside lifestyle intervention for 68 weeks. Mean weight change was −14.9% with semaglutide versus −2.4% with placebo, a treatment difference of 12.4 percentage points. Weight reductions of at least 5%, 10% and 15% were reached by 86.4%, 69.1% and 50.5% of the semaglutide group. Gastrointestinal events were the main adverse events and led to discontinuation in 4.5% versus 0.8% (Wilding et al., 2021).
The STEP 1 extension followed a subset for a further year after both drug and lifestyle intervention were withdrawn. Participants regained two-thirds of their prior weight loss, and cardiometabolic improvements reverted towards baseline in parallel. The authors concluded that obesity behaves as a chronic condition requiring ongoing treatment (Wilding et al., 2022). For anyone designing a study of GLP-1-class compounds, this extension is the reference for what an off-treatment arm should expect to show.
Cardiovascular Outcomes Without Diabetes: SELECT
SELECT tested whether the cardiovascular benefit seen in diabetes extended to people with obesity but no diabetes. It enrolled 17,604 patients aged 45 or over with pre-existing cardiovascular disease and BMI of 27 or more, randomised 1:1 to semaglutide 2.4 mg or placebo, and followed them for a mean of 39.8 months. The primary composite endpoint occurred in 6.5% of the semaglutide group versus 8.0% on placebo (hazard ratio 0.80) (Lincoff et al., 2023).
A pre-specified analysis of weight in SELECT found that weight loss continued for about 65 weeks and was then sustained for up to four years: at 208 weeks the semaglutide group was 10.2% below baseline versus 1.5% for placebo, with clinically meaningful loss across sexes, races, body sizes and regions (Ryan et al., 2024). This is the longest on-treatment weight dataset for any incretin drug.
Kidney and Liver Outcomes
FLOW randomised 3,533 patients with type 2 diabetes and chronic kidney disease to semaglutide 1.0 mg or placebo. The trial was stopped early at a pre-specified interim analysis: the risk of the primary composite (kidney failure, at least a 50% fall in eGFR, or death from kidney or cardiovascular causes) was 24% lower with semaglutide (hazard ratio 0.76), and cardiovascular death was 20% lower (Perkovic et al., 2024).
In metabolic dysfunction-associated steatohepatitis, the ESSENCE phase 3 trial assigned 1,197 patients with biopsy-confirmed MASH and stage 2–3 fibrosis to semaglutide 2.4 mg or placebo. At the planned 72-week interim analysis of the first 800 patients, steatohepatitis resolved without worsening fibrosis in 62.9% versus 34.3%, and fibrosis improved without worsening steatohepatitis in 36.8% versus 22.4% (Sanyal et al., 2025). The trial continues to 240 weeks for clinical outcomes.
Safety Profile in the Published Trials
Gastrointestinal events (nausea, vomiting, diarrhoea, constipation) are the dominant adverse effect across every programme, most frequent during dose escalation and generally transient. Pancreatitis and gallbladder events are monitored across trials and appear at low rates. Thyroid C-cell tumours seen in rodents underlie a class boxed warning, though the relevance to humans is unresolved. Hypoglycaemia is uncommon unless semaglutide is combined with insulin or sulfonylureas, because insulin secretion is glucose-dependent. A narrative review of the safety literature is available in Frontiers in Endocrinology (Smits and Van Raalte, 2021).
Every one of those findings comes from pharmaceutical-grade material with validated identity and potency. They do not transfer to research-grade material of unknown purity, which is the subject of the next section.
Platform Market Data: Semaglutide Listings
The Peptides.SO listings table holds 10,922 priced listings across 119 suppliers (prices checked 24–25 September 2026). Semaglutide is listed by 23 of those suppliers.
| Product row | Listings | Suppliers | Median list price | Interquartile range | Median at sale |
|---|---|---|---|---|---|
| Semaglutide (all sizes) | 51 | 23 | $119.99 | $90.00 – $214.87 | $111.00 |
| Semaglutide 5 mg | 12 | 10 | $97.50 | — | — |
| Semaglutide 10 mg | 12 | 9 | $144.50 | — | — |
The listed range runs from $30 to $539.99; the top end is multi-vial kits stored under the same product row. For comparison, tirzepatide and retatrutide are listed at platform medians of $185.50 and $169 respectively, so semaglutide is the least expensive of the three incretin compounds on the research market. Current prices, supplier count and stock are on the semaglutide product page; the cost calculator converts list prices to cost per milligram.
Because semaglutide is a marketed pharmaceutical, research-grade vials have a reference standard to be tested against, which is not true of investigational compounds. A useful certificate of analysis for semaglutide shows HPLC purity, mass spectrometry confirming the expected molecular mass of the acylated peptide (not just the backbone), and an endotoxin result. Suppliers on this platform are compared on those criteria in the supplier checklist and the GLP-1 sourcing guide.
Handling Notes for Laboratory Material
Research-grade semaglutide is supplied lyophilised. Like other acylated peptides it forms aggregates if agitated after reconstitution and degrades with repeated freeze-thaw cycles and light exposure. Lyophilised vials are stored frozen; reconstituted solutions are refrigerated and used within the period the supplier's stability data supports. The peptide calculator converts vial mass and diluent volume to concentration for in vitro or analytical work. These are handling notes for laboratory material only.
Related Reading
- •GLP-1 receptor agonists: complete research overview
- •Retatrutide triple agonist research profile
- •Retatrutide vs tirzepatide
- •Half-life tool for modelling once-weekly exposure
Frequently Asked Questions
What is the difference between Ozempic, Wegovy, Rybelsus and research-grade semaglutide?
The first three are approved pharmaceutical products containing semaglutide at defined strengths with validated manufacturing. Research-grade semaglutide is a chemical sold to laboratories with no such validation; its identity and purity are whatever the supplier's certificate shows.
How long does semaglutide stay in the body?
The elimination half-life is about one week in humans, which is why it is dosed weekly in trials and why steady state takes four to five weeks to reach.
How much weight was lost in the obesity trials?
In STEP 1, mean weight change over 68 weeks was −14.9% versus −2.4% with placebo. In SELECT, weight loss plateaued at about 65 weeks and was sustained for four years at −10.2% versus −1.5%.
What happens after stopping?
In the STEP 1 extension, participants regained about two-thirds of their lost weight in the year after withdrawal, and cardiometabolic markers reverted towards baseline.
Does semaglutide reduce cardiovascular events?
In SUSTAIN 6 (type 2 diabetes, high cardiovascular risk) the primary composite fell from 8.9% to 6.6%; in SELECT (obesity, established cardiovascular disease, no diabetes) it fell from 8.0% to 6.5%.
Why is semaglutide cheaper than retatrutide on the research market?
It has been commercially synthesised at scale since 2017 and has a reference standard, so more suppliers can source and verify it; 23 suppliers list it on this platform against 27 for retatrutide, but at a 30% lower median price.
References
1. Lau J, et al. Discovery of the Once-Weekly Glucagon-Like Peptide-1 (GLP-1) Analogue Semaglutide. J Med Chem. 2015. PMID 26308095
2. Yang XD, Yang YY. Clinical Pharmacokinetics of Semaglutide: A Systematic Review. Drug Des Devel Ther. 2024. PMID 38952487
3. Marso SP, et al. Semaglutide and Cardiovascular Outcomes in Patients with Type 2 Diabetes. N Engl J Med. 2016. PMID 27633186
4. Pratley RE, et al. Semaglutide versus dulaglutide once weekly in patients with type 2 diabetes (SUSTAIN 7). Lancet Diabetes Endocrinol. 2018. PMID 29397376
5. Aroda VR, et al. PIONEER 1: Randomized Clinical Trial of the Efficacy and Safety of Oral Semaglutide Monotherapy in Comparison With Placebo in Patients With Type 2 Diabetes. Diabetes Care. 2019. PMID 31186300
6. Wilding JPH, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity. N Engl J Med. 2021. PMID 33567185
7. Wilding JPH, et al. Weight regain and cardiometabolic effects after withdrawal of semaglutide: The STEP 1 trial extension. Diabetes Obes Metab. 2022. PMID 35441470
8. Lincoff AM, et al. Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes. N Engl J Med. 2023. PMID 37952131
9. Ryan DH, et al. Long-term weight loss effects of semaglutide in obesity without diabetes in the SELECT trial. Nat Med. 2024. PMID 38740993
10. Perkovic V, et al. Effects of Semaglutide on Chronic Kidney Disease in Patients with Type 2 Diabetes. N Engl J Med. 2024. PMID 38785209
11. Sanyal AJ, et al. Phase 3 Trial of Semaglutide in Metabolic Dysfunction-Associated Steatohepatitis. N Engl J Med. 2025. PMID 40305708
12. Jalleh RJ, et al. Gastrointestinal effects of GLP-1 receptor agonists: mechanisms, management, and future directions. Lancet Gastroenterol Hepatol. 2024. PMID 39096914
13. Drucker DJ. GLP-1 physiology informs the pharmacotherapy of obesity. Mol Metab. 2022. PMID 34626851
14. Smits MM, Van Raalte DH. Safety of Semaglutide. Front Endocrinol. 2021. PMID 34305810
Research Disclaimer
Research-grade semaglutide is sold for laboratory use only and is not the approved medicine. This article reports published trial results to describe the molecule; it does not recommend, describe or endorse administration to people or animals. Trial doses are quoted only to identify the results they belong to. Anyone considering GLP-1 therapy should consult a licensed clinician about the approved products.