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Tirzepatide

Dual GIP and GLP-1 receptor agonist

Also known as GIP/GLP-1 dual agonist, Mounjaro, Zepbound

A dual incretin agonist hitting both GIP and GLP-1 receptors. Phase III results in diabetes and obesity are larger than single-agonist comparators; the mechanistic reason is still argued.

Guide updated Sep 2, 2026Literature checked Sep 2, 20262 curated studies62 literature recordsBaseline editorial

Overview

In shortOne peptide that switches on two gut-hormone receptors instead of one. The bet was that two would beat one, and the big trials broadly bore that out. Why it works better is still genuinely argued.

Tirzepatide is a single 39-amino-acid peptide that activates both the GIP and GLP-1 receptors. It was developed on the hypothesis that co-agonism would outperform GLP-1 agonism alone, and the SURPASS (type 2 diabetes) and SURMOUNT (obesity) programmes have broadly borne that out on the endpoints tested.

The interesting scientific question is why. GIP agonism alone was long considered a dead end in obesity, and there is a live argument about whether the added benefit comes from GIP receptor agonism, from partial desensitisation resembling antagonism, or from pharmacokinetic properties unrelated to the second receptor.

Mechanism

In shortIt acts on two receptors. One does the familiar things: insulin when blood sugar is high, less appetite, slower stomach emptying. What the second one contributes is honestly unsettled, because in animal studies both switching it on and blocking it helped with weight.

Tirzepatide engages both incretin receptors, with a binding profile that is more GIP-like than GLP-1-like in vitro. GLP-1 receptor engagement produces the familiar glucose-dependent insulin secretion, glucagon suppression, delayed gastric emptying, and appetite reduction.

The GIP contribution is genuinely unsettled. GIP receptor agonism and antagonism have both produced weight benefit in preclinical models, which is the kind of result that should make anyone cautious about confident mechanistic stories. Adipose tissue effects, central appetite pathways, and receptor desensitisation are all live candidates.

Evidence

In shortStrong, and tested against a real competitor rather than just placebo. At the highest dose people lost about 20.9% of their body weight over 72 weeks. Head to head it beat semaglutide on both blood sugar and weight in type 2 diabetes. The same questions remain about what happens after stopping.

Strong for glycaemic control and weight reduction, from large pre-registered phase III trials with active comparators. Which is a higher bar than placebo control.

SURMOUNT-1 reported mean weight reduction around 20.9% at the highest dose over 72 weeks in adults with obesity without diabetes. SURPASS-2 compared tirzepatide directly against semaglutide in type 2 diabetes and reported greater HbA1c and weight reduction.

As with semaglutide, durability after discontinuation and long-term outcome data remain the open questions, and head-to-head comparisons at matched tolerability rather than matched dose are scarce.

Safety

In shortMuch the same as the GLP-1 drugs: mostly stomach effects, worst while the dose is being raised. The same thyroid cancer contraindication and the same pancreas and gallbladder concerns apply. Prescription only, and most of the harm in this class happens when people get it outside medical supervision.

The adverse effect profile is dominated by gastrointestinal events, dose-related and concentrated during escalation, and broadly resembles GLP-1 agonists.

The rodent thyroid C-cell signal and the associated contraindication in medullary thyroid carcinoma and MEN2 carry over. Pancreatitis, gallbladder events, and periprocedural aspiration concerns apply as they do across the class.

Prescription medicine requiring supervision. Supply outside that supervision is where most of the harm in this class actually happens.

Regulatory status

In shortApproved in several countries for type 2 diabetes and for weight management, under different brand names. Doses, approved uses and cost vary by country, and supply has been tight in several markets.

Approved in several jurisdictions for type 2 diabetes and for chronic weight management under separate brand names. Approved indications, available doses, and reimbursement differ significantly by country, and supply has been constrained in several markets.

The literature

2 studies indexed. Findings and limitations get equal weight, on purpose.

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The wider literature

21 indexed papers and 41 registered trials mentioning Tirzepatide, straight from PubMed and ClinicalTrials.gov. 39 of 41 administer it; the rest measure it. These have not been read by us. Unlike the studies above, they carry no findings and no limitations written by anyone here, because writing either would mean claiming a reading nobody has done. They are a starting point for yours.

Registered trials (41)

  1. A Study to Evaluate ALN-2232 in Participants With Obesity

    Alnylam Pharmaceuticals2026NCT07463846

    interventionalphase1phase2recruitingn=156

  2. Tirzepatide to Reduce rEcurrence And Burden After Ablation of Atrial Fibrillation

    National Taiwan University Hospital2026NCT07382024

    interventionalnanot yet recruitingn=200

  3. Tirzepatide in Thrombectomy-Treated Acute Ischemic Stroke: A Randomized Trial

    yifang zhu2026NCT07734792

    interventionalphase2phase3not yet recruitingn=430

  4. A Study of SYH2069 Injection in Participants With T2DM Not Controlled With Diet/Exercise Alone or Metformin

    CSPC Ouyi Pharmaceutical Co., Ltd.2026NCT07796477

    interventionalphase2not yet recruitingn=240

  5. DECODE - Haemodynamic Effects Of Semaglutide and Tirzepatide - a Series of Pilot Studies

    Cambridge University Hospitals NHS Foundation Trust2026NCT07483801

    interventionalphase4not yet recruitingn=112

  6. Comparative Observation of Metabolic and Pharmacologic Adipose Remodeling With Enhanced Incretin AgonisTs

    Tri-Service General Hospital (TSGH)2026NCT07589322

    interventionalnarecruitingn=120

  7. Incretin Therapies in Obesity-related HFpEF

    Columbia University2026NCT07554638

    interventionalphase4recruitingn=50

  8. Tirzepatide for Treatment of CCCA

    Johns Hopkins University2026NCT07734870

    interventionalphase2not yet recruitingn=20

  9. Can Fat-Burning Shots Boost Fertility? Comparing Weight-Loss Injections vs. Healthy Habits for Obese Men With Low Sperm Health

    First Affiliated Hospital of Wenzhou Medical University2026NCT07179120

    interventionalphase2not yet recruitingn=180

  10. Tirzepatide (Spartina) in Obese Kidney Transplant Recipients

    Shahid Beheshti University of Medical Sciences2026NCT07423247

    interventionalphase4recruitingn=30

  11. Tirzepatide on Atrial Fibrillation Recurrence After Catheter Ablation in Patients With Obesity and HFpEF

    Yunlong Wang2026NCT07630454

    interventionalphase4not yet recruitingn=602

  12. Real-world Effectiveness and Dosing Patterns of Tirzepatide in People With Obesity

    Radboud University Medical Center2026NCT07504172

    observationalnot yet recruitingn=1700

  13. A Trial Within Cohort Feasibility Study Design Comparing Standard of Care Versus Weight Loss (Achieved Through Tirzepatide) for Obesity-related Hypertension in Young Adults

    Cambridge University Hospitals NHS Foundation Trust2026NCT07364175

    interventionalnarecruitingn=60

  14. Comparing Facial Aging Between Identical Twins With 3D Imaging

    Ponsky Facial Aesthetics And Plastic Surgery, Llc2026NCT07760532

    observationalnot yet recruitingn=200

  15. CARTIZ Registry: Cartilage, Arthropathy and Imaging Under Tirzepatide in Zone-stratified Cohorts - A Four-Institute Mexican Observational Registry

    JULIO GRANADOS MONTIEL2026NCT07567378

    observationalnot yet recruitingn=30

  16. Safety and Effectiveness of Tirzepatide in Patients With Obesity at Hospital de Clínicas, Paraguay

    LABORATORIOS INDUFAR2026NCT07492563

    observationalnot yet recruitingn=300

  17. Spartina® (Tirzepatide) Effectiveness and Safety Evaluation

    Cinnagen2025NCT07262762

    observationalcompletedn=175

  18. Effects of Long-Acting GLP-1 (Glucagon-like Peptide-1) or Dual Incretin (GLP-1 and GIP [Glucose-dependent Insulinotropic Peptide]) Modulation on Gastric Motor Functions

    Mayo Clinic2025NCT06801015

    interventionalphase4active not recruitingn=30

  19. Tirzepatide for Alcohol Use Disorder

    University of Southern California2025NCT06994338

    interventionalphase2recruitingn=42

  20. Tirzepatide in PWS, HO and GNSO

    Grace Kim2025NCT06901245

    interventionalphase4recruitingn=36

  21. Tirzepatide for Obesity and Meth Use Disorder

    University of Texas Southwestern Medical Center2025NCT06745128

    interventionalphase2active not recruitingn=45

  22. A Study of Tirzepatide in Adolescents With Obesity and Weight-Related Comorbidities (SURMOUNT-ADOLESCENTS-2)

    Eli Lilly and Company2024NCT06439277

    interventionalphase3recruitingn=300

  23. Evaluate the Efficacy of TIRZEPATIDE for the Treatment of Moderate to Severe HS Hidradenitis Suppurativa

    Florida Academic Centers Research and Education, LLC2024NCT06301256

    interventionalnaunknownn=20

  24. A Study to Investigate Weight Management With LY3841136 and Tirzepatide (LY3298176), Alone or in Combination, in Adult Participants With Obesity or Overweight With Type 2 Diabetes

    Eli Lilly and Company2024NCT06603571

    interventionalphase2active not recruitingn=367

  25. Ixekizumab Concomitantly Administered With Tirzepatide in Adults With Moderate-to-Severe Plaque Psoriasis and Obesity or Overweight

    Eli Lilly and Company2024NCT06588283

    interventionalphase3completedn=281

  26. Comparative Effectiveness of Two Initial Combination Therapies in Patients With Recent Onset Diabetes

    The University of Texas Health Science Center at San Antonio2024NCT06246799

    interventionalphase3recruitingn=256

  27. Tirzepatide for Weight Loss Intervention in Early-Stage Hormone Receptor Positive/HER2 Negative Breast Cancer

    Rutgers, The State University of New Jersey2024NCT06518837

    interventionalphase2recruitingn=40

  28. A Research Study to See How Much CagriSema Lowers Blood Sugar and Body Weight Compared to Tirzepatide in People With Type 2 Diabetes Treated With Metformin, SGLT2 Inhibitor or Both

    Novo Nordisk A/S2024NCT06534411

    interventionalphase3completedn=1023

  29. Effects of RDX-002 on Postprandial Triglycerides in Patients Discontinuing GLP-1 Agonists

    Response Pharmaceuticals2024NCT06640972

    interventionalphase2completedn=68

  30. A Study of Investigational Tirzepatide (LY3298176) Doses in Participants With Type 2 Diabetes and Obesity

    Eli Lilly and Company2023NCT06037252

    interventionalphase2active not recruitingn=414

  31. Phase 1/1b Study of TLC-6740 in Healthy Subjects and Subjects With Obesity, With or Without Diabetes

    OrsoBio, Inc2023NCT05822544

    interventionalphase1active not recruitingn=564

  32. A Study of Tirzepatide (LY3298176) in Chinese Participants With Type 2 Diabetes (SURPASS-CN-MONO)

    Eli Lilly and Company2023NCT05963022

    interventionalphase3completedn=206

  33. A Study of Tirzepatide (LY3298176) on the Reduction on Morbidity and Mortality in Adults With Obesity

    Eli Lilly and Company2022NCT05556512

    interventionalphase3active not recruitingn=15374

  34. Effects of Tirzepatide and Insulin Glargine on Glucolipid Metabolism and Brain Function in Patients With Type 2 Diabetes

    Nanjing First Hospital, Nanjing Medical University2022NCT05553093

    interventionalphase4recruitingn=150

  35. A Study of Tirzepatide (LY3298176) in Chinese Participants Without Type 2 Diabetes Who Have Obesity or Overweight (SURMOUNT-CN)

    Eli Lilly and Company2021NCT05024032

    interventionalphase3completedn=210

  36. A Study of the Effect of Tirzepatide on How the Body Handles Birth Control Pills in Healthy Female Participants

    Eli Lilly and Company2020NCT04172987

    interventionalphase1completedn=40

  37. A Study of Tirzepatide (LY3298176) Versus Insulin Lispro (U100) in Participants With Type 2 Diabetes Inadequately Controlled on Insulin Glargine (U100) With or Without Metformin

    Eli Lilly and Company2020NCT04537923

    interventionalphase3completedn=1428

  38. A Study to Measure Stomach Emptying in Overweight Non-diabetic and Diabetic Participants Using Tirzepatide

    Eli Lilly and Company2020NCT04407234

    interventionalphase1completedn=36

  39. A Study of Tirzepatide (LY3298176) in Participants With Obesity or Overweight

    Eli Lilly and Company2019NCT04184622

    interventionalphase3completedn=2539

  40. A Study of Tirzepatide at Different Injection Sites in Participants With Different Body Sizes

    Eli Lilly and Company2019NCT04050670

    interventionalphase1completedn=54

  41. A Study of Tirzepatide (LY3298176) Versus Insulin Degludec in Participants With Type 2 Diabetes

    Eli Lilly and Company2019NCT03882970

    interventionalphase3completedn=1444

Papers (21)

  1. Comparison of Clinical Efficacy and Safety of Tirzepatide, Liraglutide and Semaglutide in Patients with Obesity and Without T2D: A Bayesian Network Meta-Analysis of Randomised Controlled Trials.

    Ciudin A, et al.Advances in therapy2026PMID 41820778

    journal articlenetwork meta-analysiscomparative studysystematic review

  2. Efficacy and safety of tirzepatide in children and adolescents with type 2 diabetes (SURPASS-PEDS): a randomised, double-blind, placebo-controlled, phase 3 trial.

    Hannon TS, et al.Lancet (London, England)2025PMID 40975112

    journal articleclinical trial, phase iiirandomized controlled trialmulticenter study

  3. Semaglutide and Tirzepatide in Patients With Heart Failure With Preserved Ejection Fraction.

    Krüger N, et al.JAMA2025PMID 40886075

    comparative studyjournal articleobservational study

  4. Indirect comparative efficacy and safety of tirzepatide 10 and 15 mg versus semaglutide 2.4 mg for the management of obesity and overweight in patients with type 2 diabetes.

    Ciudin A, et al.Diabetes, obesity & metabolism2025PMID 40537987

    clinical trial, phase iiicomparative studyjournal articlemulticenter studyrandomized controlled trial

  5. Tirzepatide as Compared with Semaglutide for the Treatment of Obesity.

    Aronne LJ, et al.The New England journal of medicine2025PMID 40353578

    clinical trial, phase iiicomparative studyequivalence trialjournal articlemulticenter study

  6. Reasons for Discontinuation of Obesity Pharmacotherapy With Semaglutide or Tirzepatide in Clinical Practice.

    Gasoyan H, et al.Obesity (Silver Spring, Md.)2025PMID 41039650

    journal article

  7. Subcutaneously administered tirzepatide vs semaglutide for adults with type 2 diabetes: a systematic review and network meta-analysis of randomised controlled trials.

    Karagiannis T, et al.Diabetologia2024PMID 38613667

    journal articlesystematic reviewnetwork meta-analysis

  8. Tirzepatide: A Review in Type 2 Diabetes.

    France NL, et al.Drugs2024PMID 38388874

    journal articlereview

  9. Semaglutide vs Tirzepatide for Weight Loss in Adults With Overweight or Obesity.

    Rodriguez PJ, et al.JAMA internal medicine2024PMID 38976257

    journal articleobservational studycomparative studyresearch support, non-u.s. gov't

  10. The impact of tirzepatide and glucagon-like peptide 1 receptor agonists on oral hormonal contraception.

    Skelley JW, et al.Journal of the American Pharmacists Association : JAPhA2024PMID 37940101

    journal articlereview

  11. Efficacy and safety of tirzepatide for treatment of overweight or obesity. A systematic review and meta-analysis.

    Tan B, et al.International journal of obesity (2005)2023PMID 37253796

    meta-analysissystematic reviewjournal article

  12. New Drug: Tirzepatide (Mounjaro(™)).

    Gettman LThe Senior care pharmacist2023PMID 36751934

    journal article

  13. Adverse Events Related to Tirzepatide.

    Mishra R, et al.Journal of the Endocrine Society2023PMID 36789109

    journal articlereview

  14. Safety issues of tirzepatide (pancreatitis and gallbladder or biliary disease) in type 2 diabetes and obesity: a systematic review and meta-analysis.

    Zeng Q, et al.Frontiers in endocrinology2023PMID 37908750

    meta-analysissystematic reviewresearch support, non-u.s. gov'tjournal article

  15. Effects of subcutaneous tirzepatide versus placebo or semaglutide on pancreatic islet function and insulin sensitivity in adults with type 2 diabetes: a multicentre, randomised, double-blind, parallel-arm, phase 1 clinical trial.

    Heise T, et al.The lancet. Diabetes & endocrinology2022PMID 35468322

    clinical trial, phase ijournal articlemulticenter studyrandomized controlled trialresearch support, non-u.s. gov't

  16. Effect of Subcutaneous Tirzepatide vs Placebo Added to Titrated Insulin Glargine on Glycemic Control in Patients With Type 2 Diabetes: The SURPASS-5 Randomized Clinical Trial.

    Dahl D, et al.JAMA2022PMID 35133415

    clinical trial, phase iiicomparative studyjournal articlerandomized controlled trialresearch support, non-u.s. gov't

  17. Management of type 2 diabetes with the dual GIP/GLP-1 receptor agonist tirzepatide: a systematic review and meta-analysis.

    Karagiannis T, et al.Diabetologia2022PMID 35579691

    journal articlemeta-analysissystematic review

  18. Efficacy and safety of a novel dual GIP and GLP-1 receptor agonist tirzepatide in patients with type 2 diabetes (SURPASS-1): a double-blind, randomised, phase 3 trial.

    Rosenstock J, et al.Lancet (London, England)2021PMID 34186022

    clinical trial, phase iiijournal articlerandomized controlled trial

  19. Dual GIP and GLP-1 Receptor Agonist Tirzepatide Improves Beta-cell Function and Insulin Sensitivity in Type 2 Diabetes.

    Thomas MK, et al.The Journal of clinical endocrinology and metabolism2021PMID 33236115

    journal articlerandomized controlled trialresearch support, non-u.s. gov't

  20. Tirzepatide.

    2006PMID 35759552

    review

  21. Tirzepatide (Mounjaro®, Zepbound®).

    1994PMID 39038307

    review

Discussion

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FeaturedPeptide ScienceDiscussion

Tirzepatide's dual agonism, from the guide's mechanism section

From the guide: Tirzepatide engages both incretin receptors, with a binding profile that is…

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