Ozempic and Wegovy: What the Trials Actually Showed
Semaglutide now has a heart disease approval too. Here is what the STEP and SELECT trial data really says, and what it does not.
Ozempic and Wegovy are the same molecule, semaglutide, sold under two names for two different jobs. That distinction matters more than most people realize, and it just got more complicated. Earlier this month, the FDA expanded Wegovy's approved use again, this time for something that has nothing to do with the scale.
On March 8, 2024, the agency approved Wegovy for cardiovascular risk reduction in adults with established heart disease who also have overweight or obesity, regardless of whether they have diabetes. It is the clearest sign yet that semaglutide's story is no longer only about body weight.
To understand how a diabetes drug from 2016 ended up here, it helps to walk through what the actual trials found, not the marketing shorthand around them.
Ozempic was approved for diabetes first
Semaglutide's first outing was as Ozempic, a once-weekly injection approved for type 2 diabetes back in 2016. It lowers blood sugar the way most GLP-1 drugs do, by boosting glucose-dependent insulin release and slowing digestion. Weight loss showed up in those diabetes trials too, but it was a side effect noted in the data, not the headline.
What the STEP 1 trial actually measured
The pivotal weight trial, STEP 1, randomized 1,961 adults with overweight or obesity, without diabetes, to weekly semaglutide 2.4 mg or placebo, alongside lifestyle counseling, for 68 weeks. Results published in The New England Journal of Medicine showed a mean body weight reduction of 14.9 percent with semaglutide compared with 2.4 percent on placebo. Coverage from AJMC at the time called it a milestone, the first non-surgical treatment to approach that scale of average weight loss in a randomized trial.
That data supported Wegovy's original approval for chronic weight management on June 4, 2021, for adults with a BMI of 30 or higher, or 27 or higher with at least one weight-related condition such as high blood pressure or type 2 diabetes.
Why the heart disease approval is a different claim
Weight loss and cardiovascular protection are not automatically the same thing, which is exactly why regulators required a dedicated outcomes trial before granting this month's approval. The trial behind it is separate from STEP 1, and its central claim is about heart attacks and strokes, not pounds lost. This is a case where a drug approved for one purpose earned a second, distinct approval only after its own dedicated evidence was reviewed.
The trial behind this approval, called SELECT, enrolled 17,604 adults with overweight or obesity and pre-existing cardiovascular disease, and found semaglutide reduced the combined risk of cardiovascular death, non-fatal heart attack, or non-fatal stroke, according to a statement from the FDA's Center for Drug Evaluation and Research summarized by the American Pharmacists Association. Coverage from AJMC quoted the agency describing Wegovy as the first weight loss medication also approved to help prevent life-threatening cardiovascular events in this population, a framing that underlines how separate this claim is from the original obesity approval.
What semaglutide has not been shown to do
None of this data supports using semaglutide as a shortcut with no downside. The most common issues in the trials were gastrointestinal, nausea, vomiting, constipation and diarrhea, especially while the dose is being increased. Semaglutide's label also carries a boxed warning regarding thyroid C-cell tumors seen in rodent studies, and the drug is not recommended for anyone with a personal or family history of medullary thyroid carcinoma. Longer-term questions, including how much lean muscle mass is lost alongside fat, remain an active area of research rather than a settled answer.
Availability has not kept pace with demand
Since 2022, both Ozempic and Wegovy have intermittently appeared on FDA and manufacturer shortage lists as prescribing volume, including substantial off-label use of the diabetes formulation for weight loss, outpaced supply. That mismatch has also fed a parallel and riskier market in compounded and counterfeit versions of the drug, a separate problem regulators are now actively trying to contain.
Semaglutide's regulatory file keeps growing rather than closing. What started as a diabetes injection is now attached to obesity, and as of this month, cardiovascular risk in people who already have heart disease. Whether it eventually earns approvals tied to kidney or other organ outcomes will depend on trials still working their way through the pipeline.
This article reports on published trial data and regulatory decisions and is not medical advice. Any decision about starting, continuing or stopping semaglutide, at any dose, belongs with a clinician who knows a patient's full medical history.
For now, the more interesting question is not whether semaglutide works, the trials answered that, but how many more conditions it will eventually be proven to help, and how many of those approvals will hold up as longer follow-up data accumulates.
Published in The Outspoken Digest
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