The Ozempic Thyroid Cancer Scare Just Got Debunked

For years, critics of GLP-1 medications have clung to one thing. The rat study. You’ve probably heard it. Something about tumors, C cells, and a warning label that the FDA slapped on drugs like Ozempic and Trulicity because in high doses, mice started sprouting thyroid growths.

This month, the largest real world data study to date just dropped in Diabetes Care, and the results are as loud as they are clear.

GLP-1 treatments do not pose and increased thyroid cancer risk in diabetics. Period.

Researchers looked at more than four million patients with type 2 diabetes from U.S. healthcare records. They compared those starting a GLP-1 med to people starting DPP-4s, SGLT2s, and sulfonylureas, which are all common second line diabetes treatments. Not only did they find no statistically significant increased risk of thyroid tumors in any comparison group, they rechecked with multiple modeling strategies and even built in a one year lag time to account for slow growing tumors. Still nothing.

And before anyone says “but what about that French study from 2023,” the authors addressed that too. The French data showed a 58 percent increased risk, but its design had holes. It did not include SGLT2s as a comparator since those weren’t yet marketed there, and it left out important confounders. This new study fixed all that using a cleaner design and more powerful datasets, and it found no signal.

What does this mean for you?

It means the black box warning on GLP-1 medications may be more about rodent fiction than human fact. It means if your doctor or insurance plan is using the thyroid scare to block your access, you now have the data on your side. And it means maybe, just maybe, we can start talking about GLP-1 medications like the life saving tools they are, without the shadow of a mouse study that never applied to us in the first place.

There’s still work to do. The warning labels have not changed. GLP-1 medications are still contraindicated in folks with a family history of medullary thyroid cancer. Tirzepatide was not included in this study yet. And the European datasets had too much confounding to be used. But this is a massive step forward in confirming what many of us have believed all along. The real risk is not the medication, it is the system that keeps people from accessing it.

I’ll be watching closely to see if this finally leads to regulatory change. Until then, you can read the study here or just forward this to the person who told you GLP-1s cause cancer.