Both Ozempic and Zepbound Protect Your Heart — New Mass General Brigham Study Involving 1 Million Patients

A major real-world study from Mass General Brigham, published in Nature Medicine and presented at the American Heart Association Scientific Sessions, confirms that both tirzepatide (Zepbound, Mounjaro) and semaglutide (Ozempic, Wegovy) provide meaningful protection against serious cardiovascular events — including heart attack, stroke, and death.

The study analyzed data from nearly one million adults with type 2 diabetes, making it one of the largest real-world comparisons of GLP-1 medications to date.

The Numbers

Researchers compared GLP-1 medications against established diabetes drugs with known cardiovascular profiles:

• Semaglutide reduced the risk of stroke and heart attack by 18 percent compared to sitagliptin — a diabetes drug with neutral cardiovascular effects that serves as a clean comparison baseline
• Tirzepatide lowered the risk of stroke, heart attack, and all-cause death by 13 percent compared to dulaglutide, another established GLP-1 with long-term cardiovascular data

Both results are clinically meaningful. The 18% reduction for semaglutide is consistent with earlier randomized trial data (SUSTAIN-6, SELECT). The tirzepatide finding is particularly significant because it fills a gap — until now, there was limited head-to-head real-world data on tirzepatide’s cardiovascular benefits compared to other GLP-1s.

Why Real-World Data Matters Here

Randomized controlled trials are the gold standard of medical evidence, but they enroll highly selected patients who often do not reflect everyday clinical reality. The Mass General Brigham team used national insurance claims databases to study patients who actually represent the diversity of people prescribed these medications — different ages, comorbidities, and health histories.

“Data generated in clinical practice and used secondarily for research allow us to address a wide range of clinically relevant questions time- and resource-effectively,” said lead author Dr. Nils Krüger, a research fellow in the Division of Pharmacoepidemiology at Mass General Brigham. “Moreover, we can study patients who reflect the reality of everyday clinical care, in contrast to the highly selected participants of randomized experiments.”

What This Means If You Have Type 2 Diabetes

If you have type 2 diabetes and are considering a GLP-1 medication, this study adds strong real-world evidence that both semaglutide and tirzepatide can protect your heart — not just help with blood sugar and weight. For patients with existing cardiovascular risk factors, this dual benefit is a significant argument in favor of GLP-1 therapy over older diabetes medications with less cardiovascular evidence.

What About Patients Without Diabetes?

This study focused on patients with type 2 diabetes. The cardiovascular data for GLP-1s in non-diabetic patients is less mature, though the SELECT trial showed semaglutide reduces cardiovascular events in overweight/obese patients with established cardiovascular disease (regardless of diabetes status). Tirzepatide’s cardiovascular outcomes trial in non-diabetic patients is ongoing.

Tirzepatide vs. Semaglutide: Which Is Better for Your Heart?

This study does not directly compare tirzepatide to semaglutide head-to-head for cardiovascular outcomes — each was compared to a different reference drug. Based on available data, both provide meaningful cardiovascular protection. Tirzepatide generally produces greater weight loss, which may translate to additional cardiovascular benefit over time, but the head-to-head cardiovascular comparison data is not yet available.

Your prescribing clinician can help you weigh the cardiovascular data against other factors including cost, access, and your specific metabolic profile.

The Bottom Line

Nearly a million patients. Published in Nature Medicine. Presented at the American Heart Association. The evidence is now compelling from multiple directions: for people with type 2 diabetes, both semaglutide and tirzepatide do more than manage blood sugar — they protect the heart. That dual benefit is reshaping how clinicians approach diabetes treatment in 2026.

Medical disclaimer: This article is for informational purposes only and does not constitute medical advice. Consult a licensed healthcare provider before starting or stopping any medication. Last updated: March 2026.