Tirzepatide and Cardiovascular Risk: What a New BMJ Cohort Study Found
TL;DR: BMJ cohort study (5 Aug 2026, n=52,971) found tirzepatide cut major cardiovascular events 32% vs sitagliptin in diabetes patients.
What Did the New BMJ Study on Tirzepatide and Cardiovascular Risk Find?
A population-based cohort study published in The BMJ on 5 August 2026 reported that people with type 2 diabetes and established atherosclerotic cardiovascular disease (ASCVD) who started tirzepatide had a substantially lower one-year risk of a major adverse cardiovascular event (MACE) than comparable patients who started sitagliptin, a DPP-4 inhibitor used here as an active, cardiovascular-neutral comparator.[1]
Among 52,971 participants aged 40 and over — 35,353 who initiated tirzepatide and 17,618 who initiated sitagliptin — the weighted one-year MACE risk was 2.9% in the tirzepatide group versus 4.4% in the sitagliptin group, a hazard ratio of 0.68 (95% CI 0.58 to 0.80), with a number needed to treat of 70.[1] The study, DOI 10.1136/bmj-2026-100011, was funded by the US National Institutes of Health and the German Heart Foundation — independent of Eli Lilly, tirzepatide's manufacturer.[2]
Velox Peptides supplies tirzepatide as an HPLC-verified (≥99% purity) lyophilised reagent for in vitro research use only. Read the research overview →
How Was the Study Designed, and Why Use Claims Data Instead of a New Randomised Trial?
The researchers used an active-comparator, new-user cohort design, drawing on two US health insurance claims databases covering May 2022 to May 2025. Rather than following patients randomised in a trial, the study identified real-world patients who were newly prescribed either tirzepatide or sitagliptin, then statistically balanced the two groups on measured baseline characteristics to emulate, as closely as observational data allows, the comparison a randomised trial would make.[1]
This approach complements rather than replaces randomised evidence. Tirzepatide's dedicated cardiovascular outcomes trial, SURPASS-CVOT, is a randomised comparison against dulaglutide, not sitagliptin, and was not designed for as large or demographically broad a population as routine US claims data can offer.[3] Claims-data cohort studies like this one test whether trial-based findings hold up in everyday practice, across a wider range of patients than a Phase 3 programme typically enrols.
What Were the Detailed Cardiovascular and Secondary Outcomes?
Population: 52,971 adults aged ≥40 with type 2 diabetes, BMI ≥25, and established ASCVD, drawn from two US claims databases (May 2022–May 2025).
Primary outcome (MACE composite): 2.9% (tirzepatide) vs 4.4% (sitagliptin) at one year; HR 0.68 (95% CI 0.58–0.80); number needed to treat ≈70.
Myocardial infarction: HR 0.67 (95% CI 0.52–0.87), favouring tirzepatide.
Ischaemic stroke: HR 0.91 (95% CI 0.64–1.28) — no statistically meaningful difference between groups.
Secondary signal: Tirzepatide initiators also had fewer infection-related events than sitagliptin initiators, which study authors suggest may point to broader biological mechanisms beyond direct atherosclerotic pathways, though this remains exploratory.
PMID: 42556854 · DOI: 10.1136/bmj-2026-100011
| Outcome | Hazard ratio (95% CI) | Interpretation |
|---|---|---|
| MACE composite | 0.68 (0.58–0.80) | Lower relative risk with tirzepatide |
| Myocardial infarction | 0.67 (0.52–0.87) | Lower relative risk with tirzepatide |
| Ischaemic stroke | 0.91 (0.64–1.28) | No meaningful difference |
Table for research reference only; confidence intervals reflect statistical uncertainty in an observational dataset.
Why Was Sitagliptin Used as the Comparator Instead of a Placebo?
Observational studies drawn from insurance claims cannot randomise anyone to receive no treatment, so researchers instead need an active comparator that behaves, cardiovascularly, like a placebo. Sitagliptin, a DPP-4 inhibitor, was selected because its own dedicated cardiovascular outcomes trial, TECOS, previously established it as cardiovascular-neutral against placebo in a randomised setting — making it a reasonable real-world stand-in for a non-incretin baseline, and a drug typically prescribed to a broadly similar population of people with type 2 diabetes.[1]
How Does This Fit With Tirzepatide's Randomised SURPASS-CVOT Trial Data?
This BMJ cohort study sits alongside, not in place of, tirzepatide's randomised cardiovascular evidence. SURPASS-CVOT, a post hoc analysis of a randomised clinical trial comparing tirzepatide with dulaglutide in people with diabetes and cardiovascular disease, reported cardiorenal findings from a controlled trial population — a different comparator and design from the claims-based analysis discussed here.[3]
Reading two study types together. A randomised trial (like SURPASS-CVOT) controls for confounding through random assignment but enrols a narrower, closely monitored population. A claims-data cohort study (like this BMJ paper) reflects everyday prescribing across a far larger, more diverse population, but cannot fully rule out that healthier or sicker patients were systematically more likely to receive one drug over the other. Convergent findings across both designs carry more weight than either alone.
For context on how tirzepatide's incretin-class relative, retatrutide, has reported on cardiovascular endpoints, see our summary of the TRIUMPH-3 Phase 3 results, where a pre-specified MACE analysis (HR 0.82, 95% CI 0.55–1.22) was reported as statistically underpowered and inconclusive — a useful contrast when comparing how differently-designed studies characterise cardiovascular signal across the GLP-1-based drug class.
What Are the Limitations of This Claims-Data Study?
Residual confounding
Despite an active-comparator, new-user design intended to reduce bias, the study cannot fully exclude the possibility that patients selected for tirzepatide differed systematically from those selected for sitagliptin in ways claims data does not capture.
Claims-data granularity
Administrative claims can misclassify diagnoses and do not capture detailed dosing, adherence, or lifestyle information available in a prospective randomised trial.
Population and follow-up
The cohort is limited to insured US adults aged 40+ with established ASCVD, followed for a relatively short one-year primary analysis window; generalisability to other populations or longer horizons is untested here.
These caveats do not invalidate the finding, but they do mean it should be read as supportive, real-world evidence that complements tirzepatide's randomised trial programme, rather than as a standalone, definitive causal claim.
Does This Affect Retatrutide's Cardiovascular Story or UK Research-Reagent Supply?
No. This is a real-world claims-data study of tirzepatide, a licensed pharmaceutical marketed as Mounjaro and Zepbound, and is entirely separate from retatrutide's own clinical programme, its ongoing FDA classification dispute, or its Q1 2027 filing timeline. It has no bearing on the UK regulatory position for research reagents under the Human Medicines Regulations 2012 — see our guide on whether research peptides are legal in the UK.
Tirzepatide and retatrutide are supplied as research reagents only. They are not medicines and have not been evaluated by the MHRA or FDA. Not for human or veterinary use. See our Research Use Policy and MHRA Statement.
References
- Tirzepatide and the risk of atherosclerotic cardiovascular events: population based cohort study. The BMJ, 5 August 2026. PMID: 42556854. DOI: 10.1136/bmj-2026-100011
- BMJ Group. GLP-1 Drug Linked to Heart Benefits for High-Risk Patients. Press release, 5 August 2026. bmjgroup.com
- TCTMD. Claims Data Lend Support to Tirzepatide's CV Effects in Patients With Diabetes. August 2026. tctmd.com
- Healio. Tirzepatide Lowers Risk for Cardiovascular Events in Real-World Setting. 6 August 2026. healio.com
- Velox Peptides. Retatrutide TRIUMPH-2 & TRIUMPH-3 Report. See our TRIUMPH-2/3 results guide for the comparable retatrutide MACE analysis.
Frequently Asked Questions
What did the new BMJ study find about tirzepatide and cardiovascular risk?
A population-based cohort study published in The BMJ on 5 August 2026 found that among 52,971 people aged 40+ with type 2 diabetes and established atherosclerotic cardiovascular disease, those who started tirzepatide had a 2.9% one-year risk of a major adverse cardiovascular event (MACE) versus 4.4% for those who started sitagliptin, a hazard ratio of 0.68 (95% CI 0.58 to 0.80).
How was the study designed?
Researchers used an active-comparator, new-user cohort design drawn from two US health insurance claims databases covering May 2022 to May 2025, comparing outcomes in 35,353 tirzepatide initiators against 17,618 sitagliptin initiators. This retrospective, real-world design emulates aspects of a randomised trial but relies on observational claims data rather than random treatment assignment.
Why was sitagliptin used as the comparator instead of a placebo?
Claims-data studies cannot randomise patients to a placebo, so researchers chose sitagliptin, a DPP-4 inhibitor previously shown in its own placebo-controlled cardiovascular outcome trial (TECOS) to be cardiovascular-neutral, as a real-world proxy for a non-incretin comparator with a similar treatment-seeking patient population.
How does this compare with tirzepatide's randomised SURPASS-CVOT trial data?
This BMJ study is observational claims-data research, distinct from SURPASS-CVOT, a randomised controlled trial comparing tirzepatide with dulaglutide. The two use different comparators and designs, so they are complementary rather than directly comparable, but both report cardiovascular findings consistent with benefit in the tirzepatide arm.
What are the limitations of this claims-data study?
As an observational cohort study, it cannot fully rule out residual confounding by indication or unmeasured differences between people prescribed tirzepatide versus sitagliptin, despite an active-comparator new-user design intended to reduce such bias. Claims data can also misclassify outcomes and lacks the granular dosing and adherence detail of a randomised trial.
Is tirzepatide available for research use?
Yes. Velox Peptides supplies tirzepatide as an HPLC-verified lyophilised research reagent for in vitro laboratory use only. It is not licensed as a medicine through Velox Peptides and is not supplied for human or veterinary use. Licensed pharmaceutical tirzepatide (Mounjaro, Zepbound) is a separate, MHRA/FDA-approved product manufactured by Eli Lilly and is not sold by Velox Peptides. Read the research overview →