GLP-1 receptor agonist
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GLP-1 receptor agonists (GLP-1 RAs, also called incretin mimetics) are a class of injectable and (in one case) oral peptide medicines that bind and activate the GLP-1 receptor.[1] They were originally developed for type 2 diabetes mellitus and have since become first-line for obesity,[2][3] approved for cardiovascular risk reduction in obesity without diabetes,[4] chronic kidney disease in T2DM,[5] and MASH with stage 2–3 fibrosis.[6]
As of 2023, GLP-1 RAs were the largest growth driver in US outpatient medicine spending, Ozempic alone accounted for $9.2 billion in Medicare Part D, second only to Eliquis across all federal programs.[7]
Mechanism
editThe GLP-1 receptor is a class B G-protein-coupled receptor expressed on pancreatic β-cells, hypothalamic satiety neurons, gastric smooth muscle, cardiomyocytes, vascular endothelium, and renal tubules.[1][8] Activation produces:
- β-cell: glucose-dependent insulin secretion, meaning hypoglycemia risk is low compared to sulfonylureas or insulin[1]
- α-cell: glucagon suppression[1]
- Stomach: delayed gastric emptying → improved postprandial glucose and prolonged satiety[1]
- CNS: hypothalamic appetite suppression and modulation of reward circuitry, the mechanism behind both the weight loss and the widely-reported "food noise" quieting[citation needed]
- Cardiovascular and renal: independent of glycemia, endothelial improvement, natriuresis, weight-mediated and weight-independent blood pressure reduction, plaque stabilization[9]
Native GLP-1 is rapidly cleaved by DPP-4 and has a plasma half-life of approximately 2 minutes.[8] Every clinically useful GLP-1 RA is engineered for DPP-4 resistance, either by amino-acid substitution at position 2 (liraglutide, semaglutide),[1] structural fusion (dulaglutide's Fc domain),[10] or by being a non-mammalian peptide (exenatide, from Gila monster venom).[11]
Approved agents
edit| Generic | Brand(s) | Maker | Route | Dosing | First FDA approval | Notes |
|---|---|---|---|---|---|---|
| Exenatide | Byetta (BID), Bydureon (weekly) | AstraZeneca (originally Amylin) | SC | BID or 1×/wk | 2005[12] | First-in-class. Exendin-4 from Heloderma suspectum venom.[11] US commercial market discontinued 2024.[citation needed] |
| Liraglutide | Victoza (T2DM), Saxenda (obesity) | Novo Nordisk | SC | Daily | 2010 (T2DM), 2014 (obesity)[13] | First daily GLP-1 RA. Acylated for albumin binding.[1] |
| Albiglutide | Tanzeum | GSK | SC | Weekly | 2014[14] | Withdrawn 2017 (commercial reasons).[citation needed] |
| Dulaglutide | Trulicity | Eli Lilly | SC | Weekly | 2014[10] | Fc-fusion construct.[10] |
| Lixisenatide | Adlyxin (US), Lyxumia (EU) | Sanofi | SC | Daily | 2016[15] | Withdrawn US 2023.[citation needed] |
| Semaglutide | Ozempic (T2DM SC), Wegovy (obesity SC), Rybelsus (oral T2DM) | Novo Nordisk | SC or oral | Weekly SC / Daily PO | 2017 SC, 2019 PO[16][17] | Highest-revenue medicine globally (2024).[citation needed] Wegovy 2.4 mg also approved for CV risk reduction in obesity[4] and MASH with fibrosis.[6] |
| Tirzepatide | Mounjaro (T2DM), Zepbound (obesity) | Eli Lilly | SC | Weekly | 2022 (T2DM), 2023 (obesity)[18] | Dual GLP-1 + GIP agonist ("twincretin"). Superior weight loss vs semaglutide in SURPASS-2[19] and SURMOUNT-1.[3] |
Problems
edit- Type 2 diabetes mellitus, first- or second-line per ADA 2025 Standards of Care,[20] especially when ASCVD, heart failure, CKD, or obesity is co-present
- Obesity or overweight with weight-related comorbidity, BMI ≥30, or ≥27 with a weight-related condition (semaglutide 2.4 mg,[21] tirzepatide,[22] liraglutide 3 mg[23])
- Cardiovascular risk reduction in obesity without T2DM, semaglutide 2.4 mg (SELECT)[4]
- MASH with stage 2–3 fibrosis, semaglutide (FDA 2025, based on ESSENCE)[6]
- CKD in T2DM, semaglutide adjunctive label (FLOW)[5]
Key trials
edit| Trial | Agent | Population | Primary result |
|---|---|---|---|
| LEADER (2016) | Liraglutide | T2DM + high CV risk | 13% ↓ MACE[24] |
| SUSTAIN-6 (2016) | Semaglutide SC | T2DM + high CV risk | 26% ↓ MACE[25] |
| REWIND (2019) | Dulaglutide | T2DM + CV risk or established CVD | 12% ↓ MACE, first GLP-1 RA benefit shown in primary prevention[26] |
| PIONEER-6 (2019) | Semaglutide PO | T2DM + high CV risk | Non-inferior to placebo[27] |
| SURPASS-2 (2021) | Tirzepatide vs semaglutide | T2DM | Tirzepatide superior on HbA1c and weight[19] |
| STEP-1 (2021) | Semaglutide 2.4 mg | Obesity without T2DM | ~14.9% body-weight loss at 68 wk[2] |
| SURMOUNT-1 (2022) | Tirzepatide | Obesity without T2DM | Up to ~22.5% body-weight loss at 72 wk[3] |
| SELECT (2023) | Semaglutide 2.4 mg | Obesity + established CVD, no T2DM | 20% ↓ MACE, landmark for obesity as a CV target[4] |
| STEP-HFpEF (2023) | Semaglutide | HFpEF + obesity | ↑ functional capacity (KCCQ), ↓ weight[28] |
| FLOW (2024) | Semaglutide | T2DM + CKD | 24% ↓ kidney + CV events; stopped early for efficacy[5] |
| ESSENCE (2025) | Semaglutide 2.4 mg | MASH + fibrosis | Histologic improvement; basis for FDA approval[6] |
Adverse effects
editCommon (≥10%, often dose-limiting):[16][21]
- Nausea, vomiting, diarrhea, constipation, dyspepsia, abdominal pain
- Worse during dose escalation; mostly tolerable with slow titration
- Approximately 75% of exenatide users experience GI side effects;[citation needed] fewer with long-acting weekly agents
Serious / labeled:
- Pancreatitis, labeled warning.[16] Real-world data are mixed; recent large cohorts do not show a clear increase, and some show decreased acute pancreatitis incidence.[9]
- Gallbladder disease, cholelithiasis is partly driven by rapid weight loss.[21]
- Medullary thyroid carcinoma (MTC) / C-cell hyperplasia, boxed warning,[16] based on rodent data. Humans show no calcitonin signal. Long-term follow-up >10 years has not been associated with increased thyroid cancer.[29] The Bezin 2023 French case-control study found a weak signal that remains heavily debated.[30] Contraindicated in personal or family history of MTC or MEN2.[16]
- NAION (non-arteritic anterior ischemic optic neuropathy), emerging signal. Small absolute risk increase.[31]
- Aspiration risk under anesthesia, delayed gastric emptying. ASA 2024 guidance: hold weekly agents 7 days pre-op; daily agents skip the morning dose.[32]
- Suicidality, initial EMA signal not replicated. Subsequent large studies suggest reduced suicidal ideation.[33] FDA removed suicidality warnings January 2026.[citation needed]
Other monitored:[16]
- Hypotension or syncope (volume depletion, especially with diuretics)
- Acute kidney injury (volume depletion from GI losses)
- Injection-site reactions (more with exenatide; antibody formation can reduce efficacy)
Interactions
editDiscovery
editThe discovery story is one of the great late-20th-century pharmacological narratives.
Native GLP-1 was isolated in the late 1980s by Jens Juul Holst (Copenhagen) and Daniel Drucker (Toronto).[8] Its therapeutic potential was obvious, and so was its problem: a 2-minute plasma half-life.[8]
In 1992, John Eng, an endocrinologist at the Bronx VA Medical Center, was reading work by Pisano and Raufman noting that the venom of the Gila monster (Heloderma suspectum) caused pancreatitis in laboratory animals.[citation needed] Eng hypothesized that the venom must contain something incretin-like, and isolated exendin-4, a 39-amino-acid peptide 53% homologous to human GLP-1, but naturally resistant to DPP-4 cleavage.[11] The VA declined to patent the discovery, so Eng patented it personally in 1993, licensed it to Amylin Pharmaceuticals, and the rest of the class, Byetta in 2005, then Victoza, Trulicity, Ozempic, Mounjaro, flowed from that single venom isolation.[citation needed]
Spending and access context
editPer CMS 2023 spending data:[7]
- Diabetes is the single largest Medicare Part D therapeutic class at $59.4 billion in 2023
- GLP-1 RAs drove most of the +$13.8 billion class growth that year
- Ozempic: $9.2 billion Part D (#2 single medicine across all federal programs, after Eliquis)
- Trulicity: $7.4 billion Part D, $2.9 billion Medicaid
- Mounjaro: $2.4 billion Part D (first full year)
These are gross figures, net spend after manufacturer rebates is materially lower, often 30–50% off list.[7]
See also
editReferences
edit- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Drucker DJ (2022). GLP-1 physiology informs the pharmacotherapy of obesity. Mol Metab 57:101351. doi:10.1016/j.molmet.2021.101351
- ↑ 2.0 2.1 Wilding JPH et al. (2021). Once-weekly semaglutide in adults with overweight or obesity (STEP-1). NEJM 384:989. doi:10.1056/NEJMoa2032183
- ↑ 3.0 3.1 3.2 Jastreboff AM et al. (2022). Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1). NEJM 387:205. doi:10.1056/NEJMoa2206038
- ↑ 4.0 4.1 4.2 4.3 Lincoff AM et al. (2023). Semaglutide and cardiovascular outcomes in obesity without diabetes (SELECT). NEJM 389:2221–32. doi:10.1056/NEJMoa2307563
- ↑ 5.0 5.1 5.2 Perkovic V et al. (2024). Effects of semaglutide on chronic kidney disease in patients with type 2 diabetes (FLOW). NEJM 391:109. doi:10.1056/NEJMoa2403347
- ↑ 6.0 6.1 6.2 6.3 Newsome PN et al. (2025). Semaglutide in MASH (ESSENCE). FDA approval basis. [citation needed]
- ↑ 7.0 7.1 7.2 Centers for Medicare & Medicaid Services. Medicare Part D Drug Spending Dashboard, 2023. Gross spending, not net of manufacturer rebates. Available at: https://data.cms.gov/summary-statistics-on-use-and-payments/medicare-medicaid-spending-by-drug
- ↑ 8.0 8.1 8.2 8.3 Holst JJ (2022). GLP-1 incretin and pleiotropic hormone with pharmacological promise. Curr Opin Pharmacol 63:102189.
- ↑ 9.0 9.1 Sattar N et al. (2021). Cardiovascular, mortality, and kidney outcomes with GLP-1 receptor agonists in patients with type 2 diabetes: a systematic review and meta-analysis. Lancet Diabetes Endocrinol 9(10):653–62. doi:10.1016/S2213-8587(21)00203-5
- ↑ 10.0 10.1 10.2 US FDA. Trulicity (dulaglutide) prescribing information. Eli Lilly and Company. https://www.accessdata.fda.gov/drugsatfda_docs/label/2022/125469s044lbl.pdf
- ↑ 11.0 11.1 11.2 Eng J et al. (1992). Isolation and characterization of exendin-4, an exendin-3 analogue, from Heloderma suspectum venom. J Biol Chem 267(11):7402–5.
- ↑ US FDA. Byetta (exenatide) approval history. https://www.accessdata.fda.gov/drugsatfda_docs/label/2009/021773s9s11s18s22s25lbl.pdf
- ↑ US FDA. Victoza (liraglutide) prescribing information. Novo Nordisk. https://www.accessdata.fda.gov/drugsatfda_docs/label/2017/022341s027lbl.pdf
- ↑ US FDA. Tanzeum (albiglutide) approval letter, 15 April 2014.
- ↑ US FDA. Adlyxin (lixisenatide) approval letter, 27 July 2016.
- ↑ 16.0 16.1 16.2 16.3 16.4 16.5 US FDA. Ozempic (semaglutide) prescribing information. Novo Nordisk. https://www.accessdata.fda.gov/drugsatfda_docs/label/2022/209637s019lbl.pdf
- ↑ US FDA. Rybelsus (semaglutide) prescribing information. Novo Nordisk. https://www.accessdata.fda.gov/drugsatfda_docs/label/2019/213051s000lbl.pdf
- ↑ US FDA. Mounjaro (tirzepatide) prescribing information. Eli Lilly. https://www.accessdata.fda.gov/drugsatfda_docs/label/2022/215866s000lbl.pdf
- ↑ 19.0 19.1 Frías JP et al. (2021). Tirzepatide versus semaglutide once weekly in patients with type 2 diabetes (SURPASS-2). NEJM 385(6):503–15. doi:10.1056/NEJMoa2107519
- ↑ American Diabetes Association. Standards of Care in Diabetes, 2025. Diabetes Care 48(Suppl. 1):S1–S352. doi:10.2337/dc25-S001
- ↑ 21.0 21.1 21.2 US FDA. Wegovy (semaglutide) prescribing information. Novo Nordisk. https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/215256s000lbl.pdf
- ↑ US FDA. Zepbound (tirzepatide) prescribing information. Eli Lilly. https://www.accessdata.fda.gov/drugsatfda_docs/label/2023/217806s000lbl.pdf
- ↑ US FDA. Saxenda (liraglutide) prescribing information. Novo Nordisk. https://www.accessdata.fda.gov/drugsatfda_docs/label/2014/206321Orig1s000lbl.pdf
- ↑ Marso SP et al. (2016). Liraglutide and cardiovascular outcomes in type 2 diabetes (LEADER). NEJM 375:311–22. doi:10.1056/NEJMoa1603827
- ↑ Marso SP et al. (2016). Semaglutide and cardiovascular outcomes in patients with type 2 diabetes (SUSTAIN-6). NEJM 375:1834–44. doi:10.1056/NEJMoa1607141
- ↑ Gerstein HC et al. (2019). Dulaglutide and cardiovascular outcomes in type 2 diabetes (REWIND). Lancet 394(10193):121–30. doi:10.1016/S0140-6736(19)31149-3
- ↑ Husain M et al. (2019). Oral semaglutide and cardiovascular outcomes in patients with type 2 diabetes (PIONEER-6). NEJM 381:841–51. doi:10.1056/NEJMoa1901118
- ↑ Kosiborod MN et al. (2023). Semaglutide in patients with heart failure with preserved ejection fraction and obesity (STEP-HFpEF). NEJM 389:1069–84. doi:10.1056/NEJMoa2306963
- ↑ Pollack R, Stokar J (2025). Long-term GLP-1 receptor agonist use is not associated with incident thyroid cancer. Diabetes Metab Res Rev 41(8):e70104.
- ↑ Bezin J et al. (2023). GLP-1 receptor agonists and the risk of thyroid cancer. Diabetes Care 46(2):384–90. doi:10.2337/dc22-1148
- ↑ Hathaway JT, Shah MP, Hathaway DB et al. (2024). Risk of nonarteritic anterior ischemic optic neuropathy in patients prescribed semaglutide. JAMA Ophthalmol 142(8):732–9. doi:10.1001/jamaophthalmol.2024.2296
- ↑ Kindel TL et al. (2024). Perioperative GLP-1 receptor agonist safety guidance. Surg Obes Relat Dis 20(12):1183–8.
- ↑ Wang W, Volkow ND, Berger NA et al. (2024). Association of semaglutide with risk of suicidal ideation in a real-world cohort. Nat Med 30:168–76. doi:10.1038/s41591-023-02672-2