Semaglutide: Mechanism of Action
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Mechanism of Action
Semaglutide selectively activates the GLP-1 receptor (GLP-1R), a Class B1 G protein-coupled receptor expressed on pancreatic beta cells, hypothalamic neurons, cardiomyocytes, and GI smooth muscle.[1]
Key Downstream Effects
| Target Tissue | Mechanism | Clinical Effect |
|---|---|---|
| Pancreatic Beta Cells | cAMP/PKA activation → glucose-dependent insulin secretion | Improved glycemic control; low hypoglycemia risk |
| Pancreatic Alpha Cells | Suppresses glucagon secretion (glucose-dependent) | Reduced hepatic glucose output |
| Hypothalamus | Activates POMC/CART neurons; inhibits NPY/AgRP | Appetite suppression; reduced caloric intake |
| GI Tract | Delays gastric emptying via vagal afferents | Increased satiety; reduced postprandial glucose |
| Cardiovascular | Anti-inflammatory, anti-atherosclerotic, endothelial protection | 20% MACE reduction (SELECT trial) |
The C18 fatty diacid acylation enables reversible albumin binding, creating a circulating depot that extends the half-life from ~2 minutes (native GLP-1) to ~168 hours, enabling once-weekly dosing.[2][8]
References
- Lau J, Bloch P, Schäffer L, et al. Discovery of the Once-Weekly Glucagon-Like Peptide-1 (GLP-1) Analogue Semaglutide. Journal of Medicinal Chemistry, 58(18), 7370-7380, 2015.
- Kapitza C, Nosek L, Jensen L, Hartvig H, Jensen CB, Flint A. Semaglutide, a once-weekly human GLP-1 analog, does not reduce the bioavailability of the combined oral contraceptive ethinylestradiol/levonorgestrel. Journal of Clinical Pharmacology, 55(5), 497-504, 2015.
- Marso SP, Bain SC, Consoli A, et al. Semaglutide and Cardiovascular Outcomes in Patients with Type 2 Diabetes. New England Journal of Medicine, 375(19), 1834-1844, 2016.
- Wilding JPH, Batterham RL, Calanna S, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1). New England Journal of Medicine, 384(11), 989-1002, 2021.
- Lincoff AM, Brown-Frandsen K, Colhoun HM, et al. Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes (SELECT). New England Journal of Medicine, 389(24), 2221-2232, 2023.
- Perkovic V, Tuttle KR, Rossing P, et al. Effects of Semaglutide on Chronic Kidney Disease in Patients with Type 2 Diabetes (FLOW). New England Journal of Medicine, 391(2), 109-121, 2024.
- Newsome PN, Buchholtz K, Cusi K, et al. A Placebo-Controlled Trial of Subcutaneous Semaglutide in Nonalcoholic Steatohepatitis. New England Journal of Medicine, 384(12), 1113-1124, 2021.
- Knop FK, Aroda VR, do Vale RD, et al. Oral semaglutide 50 mg taken once daily in adults with overweight or obesity (OASIS 1): a randomised, double-blind, placebo-controlled, phase 3 trial. The Lancet, 402(10403), 705-719, 2023.
- Husain M, Birkenfeld AL, Donsmark M, et al. Oral Semaglutide and Cardiovascular Outcomes in Patients with Type 2 Diabetes (PIONEER 6). New England Journal of Medicine, 381(9), 841-851, 2019.
- Davies M, Pieber TR, Hartoft-Nielsen ML, Hansen OKH, Jabbour S, Rosenstock J. Effect of Oral Semaglutide Compared With Placebo and Subcutaneous Semaglutide on Glycemic Control in Patients With Type 2 Diabetes (PIONEER 7). JAMA, 321(15), 1466-1480, 2019.
- Rubino D, Abrahamsson N, Davies M, et al. Effect of Continued Weekly Subcutaneous Semaglutide vs Placebo on Weight Loss Maintenance in Adults With Overweight or Obesity (STEP 4). JAMA, 325(14), 1414-1425, 2021.
- Wadden TA, Bailey TS, Billings LK, et al. Effect of Subcutaneous Semaglutide vs Placebo as an Adjunct to Intensive Behavioral Therapy on Body Weight in Adults With Overweight or Obesity (STEP 3). JAMA, 325(14), 1403-1413, 2021.
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