Semaglutide – GLP-1 receptor agonist: mechanism of action and research data

Semaglutide is one of the most extensively studied GLP-1 receptor agonists . Its pharmaceutical forms were developed for type 2 diabetes and later studied in large trials in adults with obesity . In this article we review how semaglutide works at the receptor level and what the published clinical trials report.

Semaglutide – GLP-1 receptor agonist: mechanism of action and research data

Peptology · 2026-06-04

💊 Semaglutide – GLP-1 receptor agonist: mechanism and research data

Semaglutide is one of the most extensively studied GLP-1 receptor agonists. Its pharmaceutical forms were developed for type 2 diabetes and later studied in large trials in adults with obesity. In this article we review how semaglutide works at the receptor level and what the published clinical trials report.

🧪 What is Semaglutide?

Semaglutide is a synthetic peptide, an analogue of human glucagon-like peptide-1 (GLP-1) – a hormone released from the gut after eating that regulates appetite, blood glucose and insulin secretion.

It:

Stimulates insulin secretion in response to high glucose levels
Suppresses glucagon secretion
Delays gastric emptying
Creates a feeling of satiety

The result? Reduced appetite, improved glycemic control and weight loss.

⚙️ How does Semaglutide work?

Semaglutide performs several key metabolic functions:

📉 Reduces appetite by acting on hunger centers in the brain
🔁 Slows digestion, which prolongs the feeling of fullness
💉 Increases insulin sensitivity
🩺 Stabilises blood glucose, especially in type 2 diabetes

In clinical trials, participants receiving semaglutide showed significant reductions in body weight and improvements in metabolic markers.

📊 Clinical trial results

Phase I

Assessment of safety, tolerability and pharmacokinetics

Phase II

Weight loss between 10–15% of body mass at doses 1–2.4 mg weekly

Phase III

Semaglutide leads to:

12–16% weight loss within 40–68 weeks
Significant improvement in HbA1c and glycemic profile
Reduction in triglycerides, LDL cholesterol and blood pressure

⚠️ Adverse events reported in studies

In clinical trials of semaglutide, as with other GLP-1 agonists, the most frequently reported adverse events were:

🤢 Nausea (the most common side effect, especially at initiation)
💩 Constipation or diarrhea
🤯 Headache
💤 Fatigue

🤔 Frequently Asked Questions (FAQ)

How does semaglutide differ from native GLP-1?
Native GLP-1 is broken down by the enzyme DPP-4 within minutes. Semaglutide carries amino-acid substitutions and a fatty-acid chain that binds to albumin, which extends its half-life to about one week.

Which clinical trials studied semaglutide in obesity?
Mainly the STEP programme (e.g. STEP 1: 1,961 adults, 68 weeks, −14.9% versus −2.4% with placebo) and the cardiovascular outcomes trial SELECT (17,604 adults).

Is a prescription required?
The product from Peptology is supplied for research purposes only – it does not require a prescription.

🧬 Conclusion

Semaglutide is a long-acting GLP-1 receptor agonist that acts on the pancreas, the gastrointestinal tract and the brain. Its effects on body weight, HbA1c and cardiometabolic markers have been described in large clinical trial programmes (SUSTAIN in type 2 diabetes, STEP in obesity, SELECT for cardiovascular outcomes), which makes it one of the best-documented molecules in metabolic research.

🔬 At Peptology, semaglutide is available as a research peptide for laboratory use only, with an HPLC/MS report for every batch.