Tirzepatide vs Semaglutide: Comparative Research Review – Literature Review

Research Use Only. This article is a literature summary for laboratory research use only. Nothing on this page is medical advice or an instruction for human or animal use.

Abstract

This review summarises peer-reviewed literature on Tirzepatide vs Semaglutide, with a focus on pharmacology and the published clinical literature. It describes receptor pharmacology, preclinical findings and outcomes reported in published randomised controlled trials, and notes limitations of the current evidence. It does not provide dosing, administration or preparation information.

Background

Tirzepatide (LY3298176) is a 39-amino-acid synthetic peptide with agonist activity at the GIP and GLP-1 receptors. It is an authorised prescription-only medicine in the UK for specific indications under medical supervision; material supplied for laboratory research is not a medicinal product and is not for human or veterinary use.^[1]

Semaglutide is a long-acting GLP-1 receptor agonist analogue, engineered with fatty-acid side-chain acylation and amino-acid substitution to enable albumin binding and resistance to DPP-4 degradation. It is an authorised prescription-only medicine in the UK for specific indications under medical supervision; research-grade material is not a medicinal product.^[2]

Mechanism of action

Tirzepatide is an imbalanced dual agonist: in vitro it shows affinity for the GIP receptor comparable to native GIP and weaker GLP-1 receptor affinity than native GLP-1. Preclinical work described glucose-dependent insulin secretion, effects on food intake and improvements in insulin sensitivity in rodent models.^[1,3]

Semaglutide activates the GLP-1 receptor, a class B G-protein-coupled receptor expressed on pancreatic beta cells, in the gastrointestinal tract and in brain regions involved in appetite regulation. GLP-1 receptor signalling enhances glucose-dependent insulin secretion, suppresses glucagon secretion and slows gastric emptying.^[2,3]

Summary of published research

Tirzepatide – Published clinical trial outcomes: body weight

In SURMOUNT-1 (72 weeks, adults with obesity or overweight without diabetes), mean percentage change in body weight was −15.0%, −19.5% and −20.9% across the three tirzepatide maintenance-dose arms, versus −3.1% with placebo.^[4,5]

In SURMOUNT-5, an open-label head-to-head trial in adults with obesity without diabetes, tirzepatide produced a greater mean reduction in body weight at week 72 than semaglutide (−20.2% vs −13.7%).^[4,5]

Semaglutide – Published clinical trial outcomes: body weight

In STEP 1 (68 weeks, adults with overweight or obesity without diabetes), the mean change in body weight was −14.9% with semaglutide 2.4 mg weekly versus −2.4% with placebo, alongside lifestyle intervention in both groups.^[6]

Tirzepatide – Published clinical trial outcomes: glycaemic endpoints

In SURPASS-2 (40 weeks, type 2 diabetes on metformin), tirzepatide was noninferior and superior to semaglutide 1 mg for change in HbA1c from baseline (−2.01 to −2.30 percentage points vs −1.86).^[7]

Tirzepatide – Published research: MASH

In the phase 2 SYNERGY-NASH trial in biopsy-confirmed MASH with stage F2–F3 fibrosis, a higher proportion of participants receiving tirzepatide met the primary endpoint of MASH resolution without worsening of fibrosis at 52 weeks (44–62% vs 10% placebo).^[8]

Semaglutide – Published research: MASH

In the phase 3 ESSENCE trial (biopsy-defined MASH with F2–F3 fibrosis), resolution of steatohepatitis without worsening of fibrosis at week 72 occurred in 62.9% with semaglutide versus 34.3% with placebo, and fibrosis improvement in 36.8% versus 22.4%.^[9]

Tirzepatide – Published research: heart failure

In SUMMIT, adults with heart failure with preserved ejection fraction and obesity receiving tirzepatide had a lower risk of the composite of cardiovascular death or worsening heart-failure events than placebo (hazard ratio 0.62) over a median of 104 weeks, alongside improvements in health-status scores.^[10]

Semaglutide – Published research: cardiovascular outcomes

SUSTAIN-6 reported a lower rate of major adverse cardiovascular events (MACE) with semaglutide versus placebo in type 2 diabetes at high cardiovascular risk (HR 0.74). SELECT, in people with established cardiovascular disease and overweight or obesity without diabetes, reported a 20% relative reduction in MACE (HR 0.80).^[11,12]

Semaglutide – Published research: kidney outcomes

The FLOW trial in type 2 diabetes and chronic kidney disease was stopped early for efficacy; semaglutide reduced the risk of the primary composite kidney outcome by 24% versus placebo (HR 0.76).^[13]

Tirzepatide – Reported adverse events in trials

In the SURMOUNT and SURPASS programmes, the most frequently reported adverse events were gastrointestinal (nausea, diarrhoea, constipation, vomiting), typically mild to moderate and occurring mainly during dose escalation. Discontinuation due to adverse events was more frequent than with placebo.^[4,7]

Semaglutide – Reported adverse events in trials

In STEP and SUSTAIN trials, gastrointestinal events (nausea, diarrhoea, vomiting, constipation) were the most common adverse events, generally transient and mild to moderate. Gallbladder-related events were reported more often than with placebo in some trials.^[6,11]

Limitations of the evidence

Most clinical data come from industry-sponsored trials of defined pharmaceutical formulations under medical supervision; results cannot be extrapolated to research-grade material, which is not manufactured to medicinal GMP standards. Trial populations, durations and comparators differ, so cross-trial comparisons should be interpreted cautiously. Longer-term safety data for newer agents remain limited.

Conclusion

The published literature characterises these peptides as potent incretin-pathway receptor agonists with substantial bodies of preclinical and clinical-trial data. For laboratory work, researchers should rely on primary publications and verified analytical documentation for any material used.

References

1. Coskun T et al. LY3298176, a novel dual GIP and GLP-1 receptor agonist for the treatment of type 2 diabetes mellitus: From discovery to clinical proof of concept. Mol Metab. 2018; 18:3-14. doi:10.1016/j.molmet.2018.09.009 PMID: 30473097.
2. Lau J et al. Discovery of the Once-Weekly Glucagon-Like Peptide-1 (GLP-1) Analogue Semaglutide. J Med Chem. 2015; 58(18):7370-80. doi:10.1021/acs.jmedchem.5b00726 PMID: 26308095.
3. Drucker DJ et al. Mechanisms of Action and Therapeutic Application of Glucagon-like Peptide-1. Cell Metab. 2018; 27(4):740-756. doi:10.1016/j.cmet.2018.03.001 PMID: 29617641.
4. Jastreboff AM et al. Tirzepatide Once Weekly for the Treatment of Obesity. N Engl J Med. 2022; 387(3):205-216. doi:10.1056/NEJMoa2206038 PMID: 35658024.
5. Aronne LJ et al. Tirzepatide as Compared with Semaglutide for the Treatment of Obesity. N Engl J Med. 2025; 393(1):26-36. doi:10.1056/NEJMoa2416394 PMID: 40353578.
6. Wilding JPH et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity. N Engl J Med. 2021; 384(11):989-1002. doi:10.1056/NEJMoa2032183 PMID: 33567185.
7. Frías JP et al. Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes. N Engl J Med. 2021; 385(6):503-515. doi:10.1056/NEJMoa2107519 PMID: 34170647.
8. Loomba R et al. Tirzepatide for Metabolic Dysfunction-Associated Steatohepatitis with Liver Fibrosis. N Engl J Med. 2024; 391(4):299-310. doi:10.1056/NEJMoa2401943 PMID: 38856224.
9. Sanyal AJ et al. Phase 3 Trial of Semaglutide in Metabolic Dysfunction-Associated Steatohepatitis. N Engl J Med. 2025; 392(21):2089-2099. doi:10.1056/NEJMoa2413258 PMID: 40305708.
10. Packer M et al. Tirzepatide for Heart Failure with Preserved Ejection Fraction and Obesity. N Engl J Med. 2025; 392(5):427-437. doi:10.1056/NEJMoa2410027 PMID: 39555826.
11. Marso SP et al. Semaglutide and Cardiovascular Outcomes in Patients with Type 2 Diabetes. N Engl J Med. 2016; 375(19):1834-1844. doi:10.1056/NEJMoa1607141 PMID: 27633186.
12. Lincoff AM et al. Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes. N Engl J Med. 2023; 389(24):2221-2232. doi:10.1056/NEJMoa2307563 PMID: 37952131.
13. Perkovic V et al. Effects of Semaglutide on Chronic Kidney Disease in Patients with Type 2 Diabetes. N Engl J Med. 2024; 391(2):109-121. doi:10.1056/NEJMoa2403347 PMID: 38785209.

Disclaimer: This article is for laboratory research use only. Not for human or veterinary use, not for consumption, and not intended to diagnose, treat, cure or prevent any disease. This page is an educational literature summary and is not medical advice.