A new study in The BMJ found that adding tirzepatide to standard care for patients with type 2 diabetes and heart disease was linked to a 32% relative reduction in major cardiovascular events over one year. The analysis included nearly 53,000 U.S. patients from two insurance claims databases.
A new study published in The BMJ has found that adding the GLP-1 receptor agonist drug tirzepatide, sold under the brand name Mounjaro, to standard care for patients with type 2 diabetes and established heart disease is linked to a lower risk of major cardiovascular events such as heart attack or stroke.
The researchers set out to estimate the cardiovascular effects of adding tirzepatide to standard care for patients with type 2 diabetes, a body mass index of at least 25, and established heart disease. They compared outcomes for these patients with those who received sitagliptin, another diabetes drug.
Sitagliptin was chosen as a neutral placebo proxy because several studies have shown it has no effect on cardiovascular outcomes. Randomized trials and observational studies have previously demonstrated noninferior effects of tirzepatide compared with another GLP-1 receptor agonist called dulaglutide for major adverse cardiovascular events, or MACE, which is a combined measure of heart attack, stroke, and death from any cause.
However, evidence on the effects of adding tirzepatide to standard care has been more limited, leaving both regulators and clinicians with uncertainty about how the drug performs in that context. The new study was designed to address that gap.
To answer this question, the researchers analyzed clinical practice data from two U.S. health insurance claims databases covering the period between May 2022 and May 2025. The main outcome of interest was a reduction in MACE, which was monitored from the first day of treatment up to one year, or until the individual stopped or switched treatment, or disenrolled from the health plan.
The analysis accounted for multiple factors including age, sex, race, body mass index, previous heart problems, other chronic conditions, and medication use. The researchers used a technique called propensity score overlap weighting to balance differences between the two treatment groups and draw more reliable conclusions.
A total of 52,971 individuals were included in the analysis. The average age was 70 years, and 51 percent of participants were female. Among these patients, 35,353 started tirzepatide and 17,618 started sitagliptin.
At one year, the risk of MACE was 2.9 percent in the tirzepatide group and 4.4 percent in the sitagliptin group. This represents a 32 percent relative reduction in risk. The researchers estimate that for every 70 patients starting tirzepatide, one case of MACE would be prevented.
Looking at individual components of MACE, tirzepatide was associated with a 33 percent lower risk of heart attack compared with sitagliptin. For ischemic stroke, however, there was no meaningful difference between the two treatment groups.
The study also found lower rates of infections requiring hospital admission among patients taking tirzepatide. One hospital admission for infection was prevented for every 48 patients treated with the drug. Infection-related death was also reduced, with one death prevented for every 200 patients. Death from any cause was lower as well, with one death prevented for every 122 patients.
The study has several limitations that the researchers acknowledge. The follow-up period was relatively short, which may underestimate long-term cardiovascular and safety effects. There is also possible misclassification of treatment duration or outcomes. In addition, the findings may not apply to other health care systems or to patients who do not have established cardiovascular disease.
Despite these limitations, this is an observational study, but the researchers note that they previously benchmarked their design, data, and analytics infrastructure against a randomized controlled trial before drawing conclusions about cause and effect.
The study authors conclude: "This study shows how trial-anchored evidence from clinical practice can estimate the expected cardiovascular benefit of initiating tirzepatide beyond standard background treatment and inform shared decision-making."
A linked editorial in The BMJ comments on the findings. The editorial notes that while this study provides an important, transparent estimate of what initiating tirzepatide might achieve in routine care, it does not establish a mortality indication. It also does not define the best sequence for cardiometabolic therapy.
The editorial authors say that longer follow-up, randomized and pragmatic comparisons, and more studies of additive benefit on contemporary background treatment are needed. They also point out that cardiovascular efficacy cannot benefit a population if cost, authorization barriers, supply, and discontinuation prevent sustained treatment.
As the editorial authors put it: "The signal is compelling; the causal and clinical placement questions remain open."
The study involved the work of several contributors. Gaby Clark, a scientific editor with a master's degree in English and experience in higher education and health content, served as editor. Robert Egan, a senior editor with a bachelor's degree in mathematical biology and a master's degree in creative writing, reviewed the work. Both have profiles on the publication's editorial team page.
Peptides referenced: Tirzepatide, Dulaglutide, GLP-1.
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