A UK laboratory reference summarising the published clinical trial evidence for tirzepatide (LY3298176) — the SURPASS Phase 3 programme in type-2 diabetes research and the SURMOUNT Phase 3 programme in obesity research, with a scientific overview of the peer-reviewed literature. For in-vitro research context only; no medical guidance.
Tirzepatide clinical trials are the peer-reviewed Phase 1 – Phase 3 studies of LY3298176, a dual GIP / GLP-1 receptor agonist peptide developed by Eli Lilly. The evidence base is anchored by the SURPASS programme (type-2 diabetes research) and the SURMOUNT programme (obesity research), supported by earlier pharmacokinetic and receptor-pharmacology studies. This page summarises the published literature as an evidence reference; it does not provide medical advice or treatment guidance.
The tirzepatide evidence base has grown from a single 2018 pharmacology paper into one of the most extensively published incretin literatures in modern metabolic science. Foundational receptor pharmacology (Coskun 2018, Willard 2020) established the dual GIP / GLP-1 mechanism; human pharmacokinetics (Urva 2020) supported once-weekly dosing intervals; and the Phase 3 SURPASS and SURMOUNT programmes generated the pivotal randomised controlled data across type-2 diabetes and obesity research populations.
This page summarises that published evidence at the programme level. Receptor-level pharmacology lives on the Tirzepatide mechanism of action page, and the broader laboratory research context sits on Tirzepatide research. This page does not provide medical or treatment guidance.
SURPASS is Eli Lilly's Phase 3 clinical trial programme in type-2 diabetes research populations. It is composed of six pivotal randomised trials, each pairing tirzepatide against a different comparator — placebo, semaglutide, insulin degludec, insulin glargine, insulin lispro or add-on to basal insulin — so that the dual GIP / GLP-1 mechanism can be positioned against every relevant class of active reference.
The read-outs are published across The Lancet, NEJM and JAMA and form the primary comparator dataset cited in tirzepatide receptor-pharmacology reviews.
| Trial | Research population | Comparator | Primary endpoint | Reference |
|---|---|---|---|---|
| SURPASS-1 | Drug-naïve T2D research | Placebo | HbA1c change from baseline | Rosenstock 2021 (Lancet) |
| SURPASS-2 | T2D on metformin | Semaglutide 1 mg | HbA1c change from baseline | Frías 2021 (NEJM) |
| SURPASS-3 | T2D on metformin ± SGLT2i | Insulin degludec | HbA1c change from baseline | Ludvik 2021 (Lancet) |
| SURPASS-4 | T2D with elevated CV risk | Insulin glargine | HbA1c change from baseline | Del Prato 2021 (Lancet) |
| SURPASS-5 | T2D on insulin glargine | Placebo (add-on) | HbA1c change from baseline | Dahl 2022 (JAMA) |
| SURPASS-6 | T2D on basal insulin | Insulin lispro | HbA1c change from baseline | Rosenstock 2023 |
SURMOUNT is the parallel Phase 3 clinical trial programme evaluating tirzepatide in body-weight and obesity research populations. It spans SURMOUNT-1 through SURMOUNT-5 and includes the direct head-to-head SURMOUNT-5 comparison against once-weekly semaglutide 2.4 mg.
For laboratory-supply purposes SURMOUNT is referenced as the pivotal citation set that anchors dual-incretin obesity-research reviews. Receptor-level interpretation of the SURMOUNT read-outs belongs on the mechanism of action page.
| Trial | Research population | Comparator | Primary endpoint | Reference |
|---|---|---|---|---|
| SURMOUNT-1 | Adults with obesity, without T2D | Placebo | % body-weight change | Jastreboff 2022 (NEJM) |
| SURMOUNT-2 | Adults with obesity and T2D | Placebo | % body-weight change | Garvey 2023 (Lancet) |
| SURMOUNT-3 | Adults with obesity post lead-in | Placebo | % body-weight change | Wadden 2023 |
| SURMOUNT-4 | Weight-maintenance following lead-in | Placebo | % body-weight change vs continuation | Aronne 2024 (JAMA) |
| SURMOUNT-5 | Adults with obesity — head-to-head | Semaglutide 2.4 mg | % body-weight change | Aronne 2025 (NEJM) |
From a research-literature perspective, the tirzepatide Phase 3 base scores highly on core internal-validity markers: pre-registered protocols, randomisation, active comparators, and publication in top-quartile peer-reviewed journals. The regulatory-grade dataset generated by SURPASS and SURMOUNT is now integrated into systematic reviews and meta-analyses of the dual-incretin class.
Interpretation for laboratory purposes should remain focused on what the trials characterise — the pharmacology, PK and comparative behaviour of tirzepatide — rather than on downstream clinical decisions, which sit outside the scope of this reference.
Within an in-vitro laboratory context, the SURPASS and SURMOUNT programmes provide the citation framework that justifies tirzepatide's role as a reference dual-agonist comparator. Typical uses of the trial literature in laboratory workflows include:
Every research-grade tirzepatide batch is released against the peptide-specific quality attributes summarised on laboratory quality and documented by a batch-specific COA — see the Certificate of Analysis guide and the verification library.
Reverse-phase HPLC quantifies purity as a percentage of total peak area. Release specification: ≥99%.
Learn more →Certificate of AnalysisEvery batch ships with a batch-specific COA reporting identity, purity and appearance.
Learn more →Laboratory QualityIndependent third-party analysis, temperature-controlled UK storage and full batch traceability.
Learn more →Batch VerificationCross-reference the batch number printed on your vial against our live COA library.
Learn more →Storage StandardsLyophilised at 2–8°C protected from light. Reconstituted stability ~30 days at 2–8°C.
Learn more →The tirzepatide clinical trials are the Phase 1 – Phase 3 studies of LY3298176 published in the peer-reviewed literature. The Phase 3 programme is organised into two pillars: SURPASS in type-2 diabetes research populations and SURMOUNT in obesity research populations, supported by earlier pharmacokinetic and pharmacology publications.
SURPASS is Eli Lilly's Phase 3 clinical trial programme in type-2 diabetes research. It spans SURPASS-1 to SURPASS-6, each evaluating tirzepatide against a different active comparator or background regimen — including placebo, semaglutide, insulin degludec and insulin glargine.
SURMOUNT is Eli Lilly's Phase 3 clinical trial programme in obesity research populations. It spans SURMOUNT-1 to SURMOUNT-5 and characterises tirzepatide across different body-weight research cohorts and dose steps.
The primary Phase 3 read-outs have been published in high-impact peer-reviewed journals including the New England Journal of Medicine and The Lancet, with pharmacology and PK papers in Molecular Metabolism, JCI Insight and Clinical Pharmacokinetics.
Tirzepatide has received regulatory authorisations in various jurisdictions under its branded forms. BuyRetaUK supplies research-grade tirzepatide strictly for in-vitro laboratory investigation. This page summarises published evidence and does not provide medical or prescribing guidance.
The SURPASS-2 study directly compared tirzepatide with once-weekly semaglutide in a type-2 diabetes research population. Beyond that, comparisons between the SURPASS/SURMOUNT and STEP programmes are drawn indirectly at the literature level rather than head-to-head.
Key limitations include the relatively short follow-up of many pivotal studies, the concentration of trials within one sponsor's programme, and limited long-term outcome data compared with older incretin therapies. The evidence base continues to expand.
No. This page is an educational summary of published scientific evidence for laboratory-research context. It is not medical guidance and does not discuss patient decision-making.
Peer-reviewed citations are added as each article is expanded. See our editorial standards for our sourcing and accuracy commitments.
The BuyRetaUK editorial team publishes laboratory-focused reference content on research peptides, analytical methods and Certificates of Analysis. All articles are written for in-vitro research contexts only.
View profile →Every editorial article is reviewed against our accuracy commitment and quality-assurance checklist before publication. Named reviewer profiles are added as our reviewer network expands.
View profile →Every article follows a documented editorial process — sourcing, scientific review, update cadence and correction policy — so researchers can rely on what we publish.
Read the full editorial standards →Educational first. Each step is optional — start wherever you are in your research.
Dual GIP/GLP-1 receptor overview and research framing.
How dual receptor engagement drives the incretin response.
Published evidence base, SURPASS & SURMOUNT programmes, laboratory applications.
Phase 3 SURPASS & SURMOUNT read-outs and the peer-reviewed literature.
Dual vs triple incretin agonist — how they differ.
HPLC purity and Certificate of Analysis verification.
Lyophilised storage, bacteriostatic water reconstitution, in-use stability.
Every tirzepatide vial strength available.
UK commercial hub — lab data, COAs and dispatch.
Triple vs dual incretin agonist — receptor profile and research framing.
View comparison →Side by sideSelective GLP-1 agonist vs dual GIP/GLP-1 agonist — receptor pharmacology and evidence comparison.
View comparison →Multi-compoundAll GLP-1 / GIP / glucagon research compounds in one place.
View comparison →The quality standards BuyRetaUK applies to every batch — sourcing, analytical testing, storage and traceability.
5 min read →Storage & HandlingHow to store lyophilised research peptides and reconstitute them correctly for laboratory use.
4 min read →RetatrutideA laboratory overview of retatrutide (LY3437943) — a triple agonist research peptide acting on the GLP-1, GIP and glucagon receptors.
6 min read →RetatrutideBackground on retatrutide in the academic literature — receptor pharmacology, study context and analytical handling.
8 min read →Research guides, comparisons and laboratory reference material.
Browse collection →CollectionThe UK commercial hub for research-grade Retatrutide — lab data, COAs and dispatch.
Browse collection →CollectionThe full retatrutide range with research context and lab data.
Browse collection →Every batch of Tirzepatide ships with a third-party HPLC and mass-spec Certificate of Analysis. Browse the live COA library to verify your lot.
Retatrutide is the more recently characterised compound in the academic literature, while tirzepatide is the more established reference.
Read: Retatrutide vs Tirzepatide →HPLC is the primary purity metric, but identity (mass spec) and endotoxin testing are also important components of a complete COA.
Read: Understanding HPLC Testing →Identity and purity are confirmed by independent third-party laboratories — not by us — so the result is impartial.
Read: Laboratory Quality Standards →No. Retatrutide is supplied strictly for laboratory research and is not approved for human or veterinary administration.
Read: What is Retatrutide? →Laboratory-oriented overview of the research landscape and evidence base.
Read overview →MechanismTirzepatide Mechanism of ActionReceptor-level pharmacology — GLP-1R, GIPR and signalling bias.
Read mechanism →ComparisonRetatrutide vs TirzepatideTriple vs dual incretin receptor profile — side-by-side research framing.
View comparison →
