Gathering the record
Relay is organizing the evidence and source boundaries.
GIP / GLP-1 dual receptor agonist
Tirzepatide is a once-weekly dual GIP/GLP-1 receptor agonist with FDA-approved uses and a large human evidence base. Its approved brands have different labeled indications, while several additional research areas remain investigational.
60-Second Overview
Start with what it is, why it matters, what research has shown, and what remains unknown. The science follows after the orientation.
Start here. These four answers explain why the compound matters before the page introduces the deeper science.
Tirzepatide is a medicine that influences two hormone signals involved in appetite, digestion, and blood-sugar regulation. Approved products include Mounjaro and Zepbound.
Its large development program lets researchers study weight, diabetes, sleep apnea, heart failure, and cardiovascular outcomes in clearly defined populations. This breadth helps separate a broad medicine signal from findings that belong only to one condition.
Large controlled trials have demonstrated average weight and blood-sugar improvements, while condition-specific studies have reported benefits for some other outcomes. The approved use depends on the named product and population.
Individual durability, rare harms, and uses outside studied or approved populations remain uncertain. Finished approved products also do not validate the identity or handling of independent powder vials.
The research depth, routes, studies, and primary sources below explain how Relay knows—and where the evidence stops.
Research context
Published research has investigated this compound using the following study designs.
These records explain what researchers did. They are not instructions, recommendations, or a transferable protocol.
Current FDA labeling describes product-specific administration for ZEPBOUND in the populations and indications named in the label.
Reported study administration—not a recommendation.
Research at a glance
Evidence depth, confidence, and route context explain how Relay knows—not what anyone should do.
Large Phase 3 and outcomes trials span diabetes, weight, sleep apnoea, heart failure, liver disease, and cardiovascular risk.
Research depth describes how large and mature the overall record is. It does not tell you whether the results were positive.
Multiple large randomized trials and current product labels support defined uses; unstudied populations and very long-term durability remain separate questions.
Confidence describes how reliable and consistent the conclusions are. It can be high for one outcome and low for another.
The strongest evidence type shows what the best-supported conclusions are actually based on.
Human findings are more directly relevant than animal or laboratory results, but they still apply only to the populations and outcomes studied.
Route-specific record
These are exposures used in cited research for a specific route and population—not an instruction for an individual.
Half-life describes how long it takes the measured amount in the body to fall by half. It is not a dosing recommendation.
Evidence can change by administration method. Findings from one route should not automatically be applied to another.
Evidence boundary: The label applies to the named finished injection product and its labeled presentations. It does not validate a generic lyophilized vial, independent concentration, diluent choice, or reconstitution process. Amounts shown describe cited research exposure—not a dosage recommendation.
Detailed evidence
Start with the strongest supported conclusion and its main uncertainty. Claim-level records below show how the evidence changes by question, population, route, formulation, and study design.
Multiple large randomized Phase 3 trials support glycaemic, weight, obstructive-sleep-apnoea, and HFpEF outcomes in defined populations. A 13,299-participant cardiovascular outcomes trial found tirzepatide noninferior—not superior—to dulaglutide for major cardiovascular events.
This is the strongest supported conclusion in the current human evidence—not a summary of every claim made about the compound.
Individual durability and tolerability over many years, rare-event characterization at population scale, and whether findings extend to unstudied populations or conditions.
Keeping the main uncertainty visible prevents an early or promising finding from looking more settled than it is.
Questions people bring to the evidence
Research questions—not promises of benefit.
It is a dual incretin agonist. Receptor activity helps explain biological effects, but clinical outcomes come from human trials and approved labeling.
The evidence base includes placebo-controlled trials, active-comparator trials, long-duration follow-up, and a cardiovascular outcomes trial.
Zepbound is labeled for adult chronic weight management and moderate-to-severe OSA in adults with obesity. Mounjaro is labeled for type 2 diabetes in adults and children age 10 and older.
Participants who continued tirzepatide after the lead-in maintained and extended average weight reduction; those switched to placebo regained weight on average.
Nausea, diarrhoea, vomiting, constipation, abdominal symptoms, and related events appear across trials and current labels, often during escalation.
Current FDA labels describe clear solution presentations in pens and vials with product-specific storage instructions.
In this defined population, the composite endpoint occurred in 9.9% of participants assigned tirzepatide and 15.3% assigned placebo. Health-status scores also improved more with tirzepatide.
After a 60-week lead-in, participants were randomized to continue their maximum tolerated dose, reduce to 5 mg, or switch to placebo for 52 more weeks. Average maintenance differed across those protocol groups.
Mechanisms
Tirzepatide (LY3298176) is a 39-amino-acid synthetic modified peptide based on the GIP sequence, with agonist activity at GIP and GLP-1 receptors. Controlled human research spans type 2 diabetes, obesity, long-term weight maintenance, obstructive sleep apnoea, cardiovascular outcomes, HFpEF with obesity, and MASH. Current evidence includes large Phase 3 placebo-controlled and active-comparator trials, more than three years of treatment follow-up in a prediabetes subgroup, a completed cardiovascular outcomes trial, and a placebo-controlled heart-failure outcomes trial in a defined population.
A plausible mechanism can explain why a study was attempted. It does not prove that the compound improves a human outcome.
Studies
Study arms are reported for transparency. They describe what researchers did in a defined record and do not transfer across identities, routes, formulations, or populations.
A later trial phase can ask a more mature question, but it does not guarantee a positive result, regulatory approval, or relevance outside the studied population.
Open-label 60-week weight-loss period followed by a 52-week double-blind randomized maintenance period
U.S. adults with obesity who lost at least 5% of body weight and tolerated tirzepatide 10 mg or 15 mg during the lead-in
At week 112, mean weight change from the original baseline was −21.9% with continued maximum tolerated tirzepatide, −16.6% after reduction to 5 mg, and −9.9% after switching to placebo.
Study administration: Continue maximum tolerated tirzepatide, reduce to 5 mg, or switch to placebo
Limitations: Randomization occurred only after a long lead-in among participants who lost weight and tolerated higher-dose tirzepatide. The U.S.-only population and protocol do not answer every long-term maintenance or discontinuation question.
Randomized, double-blind, active-controlled cardiovascular trial
Adults with type 2 diabetes and established atherosclerotic cardiovascular disease
The primary cardiovascular outcome occurred in 12.2% with tirzepatide and 13.1% with dulaglutide (hazard ratio 0.92). Tirzepatide met noninferiority, but not superiority.
Study administration: Once-weekly tirzepatide versus dulaglutide 1.5 mg
Limitations: The active comparator already has cardiovascular benefit. This was not a placebo trial and does not prove superiority.
Randomized, open-label, active-controlled trial
Adults with obesity without type 2 diabetes
Least-squares mean weight change was −20.2% with tirzepatide and −13.7% with semaglutide; waist change was −18.4 cm versus −13.0 cm.
Study administration: Maximum tolerated once-weekly tirzepatide 10 mg or 15 mg versus semaglutide 1.7 mg or 2.4 mg
Limitations: Open-label trial using maximum tolerated doses. It directly compares these two drugs under this protocol—not tirzepatide with retatrutide.
International, randomized, double-blind, placebo-controlled trial
Adults with obesity and heart failure with preserved ejection fraction
Cardiovascular death or a worsening heart-failure event occurred in 9.9% with tirzepatide and 15.3% with placebo (hazard ratio 0.62). At week 52, the between-group difference in KCCQ-CSS change was 6.9 points.
Study administration: Once-weekly subcutaneous tirzepatide up to 15 mg or placebo
Limitations: The result applies to a defined HFpEF-and-obesity population. Cardiovascular deaths were few, the composite was driven mainly by worsening heart-failure events, and the finding does not establish broad cardiovascular benefit in every population.
Prespecified 176-week treatment analysis followed by 17 weeks off treatment
SURMOUNT-1 participants with obesity and prediabetes at baseline
At week 176, mean weight change was −12.3%, −18.7%, and −19.7% with tirzepatide versus −1.3% with placebo. Diabetes developed in 1.3% of pooled tirzepatide participants versus 13.3% with placebo during treatment.
Study administration: Once-weekly subcutaneous tirzepatide 5 mg, 10 mg, or 15 mg, or placebo
Limitations: This was the prediabetes subset of one trial. The 17-week off-treatment period was too short to establish long-term durability after discontinuation.
Two randomized, double-blind, placebo-controlled trials
Adults with obesity and moderate-to-severe obstructive sleep apnoea, separated by baseline PAP use
Estimated treatment differences in AHI change were −20.0 and −23.8 events per hour in the two trials. Weight change was −17.7% versus −1.6% and −19.6% versus −2.3%.
Study administration: Maximum tolerated once-weekly tirzepatide 10 mg or 15 mg, or placebo
Limitations: People with diabetes were excluded. The trials did not establish when PAP could be stopped and do not replace individualized sleep-apnoea care.
Randomized, double-blind, placebo-controlled, biopsy-based dose-finding trial
Adults with biopsy-confirmed MASH and F2 or F3 fibrosis
MASH resolution without worsening fibrosis occurred in 44%, 56%, and 62% across tirzepatide groups versus 10% with placebo.
Study administration: Once-weekly subcutaneous tirzepatide 5 mg, 10 mg, or 15 mg, or placebo
Limitations: Phase 2 size and duration; 157 participants had evaluable week-52 biopsy results. The article was corrected in 2026; larger and longer trials are needed.
Open-label 36-week tirzepatide lead-in followed by randomized, double-blind continuation or placebo withdrawal
Adults with obesity or overweight and a weight-related condition, without diabetes
After a mean −20.9% change during the 36-week lead-in, continued treatment produced a further −5.5% mean change through week 88; switching to placebo produced a 14.0% mean regain from week 36.
Study administration: Maximum tolerated once-weekly tirzepatide 10 mg or 15 mg during lead-in; 670 participants then continued tirzepatide or switched to placebo
Limitations: Randomized participants were enriched for people who tolerated and completed the lead-in. It measures withdrawal under this protocol, not every real-world stopping scenario.
Randomized, double-blind, placebo-controlled trial
Adults with obesity or overweight and type 2 diabetes
Treatment-regimen mean weight change was −12.8% and −14.7% with tirzepatide 10 mg and 15 mg versus −3.2% with placebo.
Study administration: Once-weekly subcutaneous tirzepatide 10 mg or 15 mg, or placebo, with escalation
Limitations: The population had type 2 diabetes, so magnitude should not be generalized to people without diabetes or compared directly with separate trials.
Randomized, double-blind, placebo-controlled trial
Adults with obesity, or overweight plus a weight-related condition, without diabetes
Mean weight change at week 72 was −15.0%, −19.5%, and −20.9% across tirzepatide groups versus −3.1% with placebo.
Study administration: Once-weekly subcutaneous tirzepatide 5 mg, 10 mg, or 15 mg, or placebo, with protocol-defined escalation
Limitations: No active comparator; trial eligibility and support differ from routine care. Results cannot be ranked against retatrutide trials without a direct comparison.
Randomized, open-label, active-controlled trial
Adults with type 2 diabetes inadequately controlled by metformin
Mean HbA1c change was −2.01, −2.24, and −2.30 percentage points with tirzepatide versus −1.86 with semaglutide. Mean weight change was −7.6, −9.3, and −11.2 kg versus −5.7 kg.
Study administration: Once-weekly tirzepatide 5 mg, 10 mg, or 15 mg versus semaglutide 1 mg
Limitations: The comparator was semaglutide 1 mg in a diabetes population, not the obesity-dose regimen studied in SURMOUNT-5.
Safety snapshot
Gastrointestinal events are the most consistently reported common adverse effects.
Controlled human evidenceFrequency and severity vary by dose, population, duration, and analysis. Official warnings and contraindications remain important.
Open sourceGastrointestinal events are the most consistently reported common adverse effects.
Controlled human evidenceThe stated frequency is source-, product-, population-, route-, dose-, comparator-, and duration-specific; it is not a universal incidence estimate.
Open sourceNo source-qualified compound-specific warning or contraindication is encoded in the current record.
Evidence boundaryFDA approved as Mounjaro for type 2 diabetes and as Zepbound for defined adult weight-management and obstructive-sleep-apnoea indications Individual durability and tolerability over many years, rare-event characterization at population scale, and whether findings extend to unstudied populations or conditions.
At week 176, mean weight change was −12.3%, −18.7%, and −19.7% with tirzepatide versus −1.3% with placebo. Diabetes developed in 1.3% of pooled tirzepatide participants versus 13.3% with placebo during treatment.
Controlled human evidenceStudy discontinuation describes what happened under a study protocol; it is not an emergency-action threshold.
Open sourceNo compound-specific patient-facing urgent-action threshold is established in the current Relay record.
Evidence boundaryRelay does not infer emergency guidance from study discontinuations, mechanism, or incomplete adverse-event reporting.
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