Tirzepatide heart risk after 1 year

A 2026 Mayo Clinic Health System study followed 1,028 adults with overweight or obesity who had received continuous tirzepatide for at least 12 months. Median total body-weight loss was 12.6%, and several cardiometabolic measures improved. The study also found lower estimated 10-year atherosclerotic cardiovascular disease risk among participants who lost at least 10% of body weight. It did not show that tirzepatide prevented heart attacks, strokes, or cardiovascular deaths^[1].

What the study measured

The report, published online in the Journal of the Endocrine Society on 9 September 2026, was a retrospective observational study. Researchers reviewed routine-care data from adults treated across the Mayo Clinic Health System between June 2022 and May 2024. Everyone included had used weekly tirzepatide for at least a year. The analysis examined changes in weight, fasting glucose, HbA1c, triglycerides, alanine aminotransferase, and HDL cholesterol. HbA1c is a measure of average blood glucose over roughly three months; alanine aminotransferase is a liver enzyme^[1].

The cardiovascular-risk analysis was smaller. Of the 1,028 people in the full cohort, 275 had complete baseline and 12-month information needed to calculate estimated 10-year atherosclerotic cardiovascular disease risk. That calculator estimates the chance of a future cardiovascular event from factors such as age, blood pressure, cholesterol, smoking, and diabetes status. It is not a record of events that occurred during the study^[1].

The one-year changes were broad, but not uniform

At 12 months, median total body-weight loss was 12.6%. Fasting glucose fell 19.5%, HbA1c fell 16.0%, triglycerides fell 8.5%, and alanine aminotransferase fell 10.6%. HDL cholesterol rose 11.3%. These are associations observed in people who remained on treatment in this health-system cohort, not a comparison with a randomly assigned placebo group^[1].

Estimated 10-year cardiovascular risk did not change significantly when the 275-person analysis group was considered as a whole. The mean relative change was minus 3.7%, with a P value of .18. Results differed when researchers grouped people by weight loss. Estimated risk fell 9.6% among those who lost 10% to 20% of body weight and 14.2% among those who lost more than 20%. It did not fall significantly among people who lost less than 10%^[1].

The low-risk category grew from 38.3% to 46.4% over the year, and 11.7% of participants moved from a higher estimated-risk category to low risk. Those figures describe movement within a prediction tool. They do not establish how many heart attacks or strokes tirzepatide prevented^[1].

Why an estimated-risk result needs careful reading

A risk calculator can be useful when blood pressure, cholesterol, glycaemic markers, or smoking status change. It cannot replace an outcomes trial designed to count adjudicated cardiovascular events. This study also had no untreated comparison group, and the participants who reached larger weight-loss categories may have differed from those who did not in ways the records could not fully capture^[1].

Tirzepatide already has one randomized cardiovascular-outcomes result in a specific population. In SUMMIT, 731 adults with obesity-related heart failure with preserved ejection fraction were assigned to tirzepatide or placebo and followed for a median of 104 weeks. The composite of cardiovascular death or worsening heart-failure events occurred in 9.9% of the tirzepatide group and 15.3% of the placebo group. That is an event-based result in people with heart failure, not a general finding for every person with overweight or obesity^[2].

The SUMMIT trial was registered as NCT04847557 and specified heart failure with preserved ejection fraction and obesity as its target population. Its design therefore answers a different question from the Mayo observational report, which tracked routine-care risk markers across a broader group^[3].

Who the findings may and may not describe

The Mayo report applies most directly to adults with overweight or obesity who stayed on tirzepatide for at least 12 months within one U.S. health system. It does not tell us whether the same pattern would appear with shorter use, interrupted treatment, a different care setting, or a different mix of baseline cardiovascular risk. It also does not compare tirzepatide with semaglutide or with lifestyle care alone^[1].

For readers trying to separate research findings from treatment decisions, the tirzepatide evidence page explains its regulatory status and the wider trial record. A clinician who knows a person's cardiovascular history, other medicines, and test results is the right person to interpret whether these data apply to them.

What we do not yet know

The observational study cannot show whether the measured changes caused fewer future cardiovascular events, or whether they persist beyond one year. Its overall estimated-risk result was not statistically significant, and the more favourable estimates appeared only after grouping participants by the amount of weight they lost. The report is useful real-world evidence about cardiometabolic markers. It is not a replacement for randomized trials that measure heart attacks, strokes, heart-failure events, and cardiovascular deaths^[1].

Why this report is worth watching

The report adds a one-year view of tirzepatide in routine care, alongside the more controlled evidence from clinical trials. Its clearest result is that people who maintained treatment saw sizeable median weight loss and improvements in several measured risk factors. The cardiovascular claim should stay narrower: this cohort suggests a link between larger weight loss and lower estimated risk, while direct evidence on clinical outcomes depends on the population and the trial^[1].