People with type 2 diabetes are much more likely to develop heart disease than those without diabetes.
High blood sugar can damage blood vessels over time, increasing the risk of heart attacks, strokes, and heart failure.
Even when blood sugar is controlled, many patients remain at high risk of serious heart problems, so researchers continue searching for treatments that protect both the heart and blood sugar levels.
Tirzepatide, sold under the brand name Mounjaro, has attracted worldwide attention because it helps lower blood sugar and often leads to significant weight loss. It belongs to a newer group of medicines that work by copying natural gut hormones involved in controlling blood sugar and appetite.
Doctors have increasingly prescribed it for people with type 2 diabetes, but until recently there was limited evidence showing how much it could reduce heart problems in everyday medical practice.
A new study published in The BMJ has now provided encouraging results. Researchers examined whether adding tirzepatide to standard treatment could lower the risk of major cardiovascular events in people who already had both type 2 diabetes and established heart disease.
The investigators analysed health insurance records from two large databases in the United States between May 2022 and May 2025. They focused on adults with type 2 diabetes, a body mass index of at least 25, and existing cardiovascular disease.
Instead of comparing tirzepatide with a placebo, they compared it with sitagliptin, a diabetes medicine that has previously been shown to have little effect on heart outcomes.
The study included 52,971 patients with an average age of 70 years, and just over half were women. More than 35,000 started tirzepatide while over 17,000 received sitagliptin. Researchers adjusted for many differences between the groups, including age, weight, previous illnesses, medications, sex and race, to make the comparison as fair as possible.
After one year, the results showed that major cardiovascular events happened in 2.9% of people taking tirzepatide compared with 4.4% of those taking sitagliptin. This represented a 32% lower relative risk. The researchers estimated that treating about 70 patients with tirzepatide could prevent one major cardiovascular event such as a heart attack, stroke or cardiovascular death.
When individual outcomes were examined, people taking tirzepatide had a 33% lower risk of heart attack. However, there was no meaningful difference in the risk of ischemic stroke between the two groups.
The study also found fewer serious infections requiring hospital admission, fewer infection-related deaths and fewer deaths from any cause among people taking tirzepatide.
Although these findings are encouraging, the researchers stress that this was an observational study rather than a randomized clinical trial. Observational studies can identify strong links but cannot prove cause and effect with complete certainty because unknown differences between patients may still influence the results.
The follow-up period also lasted only about one year, making it difficult to know whether the benefits continue over many years. In addition, the results came from U.S. insurance databases, so they may not fully apply to countries with different healthcare systems or to people without existing heart disease.
An accompanying editorial noted that important questions remain. Researchers still need longer studies to determine the best order for using newer diabetes medicines, how they should be combined with other treatments, and whether their benefits remain strong over the long term.
Access is another challenge because high prices, insurance restrictions and medicine shortages may prevent many patients from receiving ongoing treatment.
Overall, this study adds important real-world evidence suggesting that tirzepatide may protect the heart as well as control diabetes in people already living with cardiovascular disease. If future long-term studies confirm these findings, the medicine could become an even more important part of diabetes care.
One major strength of this research is its very large sample size and the use of real-world clinical data, making the findings relevant to everyday medical practice. The researchers also used advanced statistical methods to reduce differences between groups.
However, because patients were not randomly assigned to treatment, the results should be interpreted carefully until confirmed by additional randomized trials with longer follow-up.
Source: The BMJ.
