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Semaglutide: what the research shows, and what it doesn’t

By Pinnacle Pulse Editorial Team · Status as of 16 October 2026 · Next scheduled update: 14 January 2027

Short answer: Semaglutide is an authorized prescription medicine, tested in large randomized trials in type 2 diabetes, obesity and heart disease. Those trials say a lot about the licensed drug used with a doctor’s supervision, side effects included. About unapproved copies sold online as research chemicals, they say nothing at all.

What semaglutide is

It’s a GLP-1 receptor agonist. In plain language, it imitates a hormone your gut releases after eating, one that nudges insulin release and dampens appetite. The EU authorized the first semaglutide medicine in February 2018. Several more products, for different conditions, have since been approved in the EU and the US, and you need a prescription for every one of them.

One thing up front. This page won’t tell you whether semaglutide is a good idea for you. That’s a conversation for a doctor who has your chart open.

What has been studied

Here the contrast with most of this site is stark. For BPC-157 we are counting rat studies. For semaglutide we’re counting randomized trials with thousands of participants each, the kind of design that can actually separate a drug’s effect from chance. We picked three of the best known because they cover different groups of patients, plus one pooled analysis of side effects. Nearly all of the big trials were paid for by the manufacturer. That’s standard for approval studies, and you should still keep it in the back of your mind.

Type 2 diabetes and the heart

SUSTAIN-6 came out in the New England Journal of Medicine in 2016. Its 3,297 participants had type 2 diabetes and a high risk of heart disease, and they were followed for two years. The trial’s real job was reassurance: regulators wanted proof that the drug didn’t push cardiovascular risk up. As it turned out, heart attacks, strokes and cardiovascular deaths, counted together, were less common on semaglutide.

Then comes the part that gets less airtime. Complications of diabetic retinopathy, a disease of the retina, were more frequent in the semaglutide group, with a hazard ratio of 1.76. Serious adverse events overall were rarer on the drug. Even so, more people quit it because of side effects, mostly stomach and gut problems.

Obesity without diabetes

STEP 1 (NEJM, 2021) enrolled 1,961 adults with overweight or obesity who did not have diabetes. Everyone got a lifestyle program; on top of that, people received either semaglutide or placebo for 68 weeks. The trial measured weight change, and semaglutide came out ahead. Nausea and diarrhea topped the list of side effects. Gut problems made 4.5% of the semaglutide group stop, compared with 0.8% of the placebo group.

SELECT (NEJM, 2023) is the giant: 17,604 people who already had heart disease and were overweight or obese, again without diabetes. Major cardiovascular events were less common with semaglutide. Read a little further into the paper, though. One in six participants on the drug (16.6%) stopped it permanently because of adverse events. On placebo it was 8.2%, roughly half.

Side effects, pooled

In 2025 a team writing in the Annals of Saudi Medicine combined 13 randomized trials, 26,894 people in all, every one of them with obesity and none with diabetes. Gastrointestinal complaints were more common on semaglutide than on placebo, though mostly mild. Gallbladder problems were more common too, gallstones especially. Liver and pancreas problems were not significantly increased.

What the research does not show

Start with the obvious gap. Not one of these trials used semaglutide bought from a website. FDA says some products online are labeled "for research purposes" or "not for human consumption". It also says salt versions like semaglutide sodium and semaglutide acetate have no lawful basis in compounding. By 31 May 2026 the agency had logged 990 adverse-event reports tied to compounded semaglutide, some of them after dosing mistakes. In the EU, EMA warned in September 2025 about a sharp rise in illegal GLP-1 medicines sold online.

Then there is time. The trials above lasted from 68 weeks to a little over three years on average. Nobody has decades of data yet.

People who were excluded from the trials, often including pregnant women and people with certain illnesses, aren’t represented in the results. And an average across thousands of people is a poor guide to how any single person will react.

Last, the results come from a setting with supervision, slow dose increases and regular check-ups. Take those away and you are outside what was tested.

Semaglutide is prescription-only in the EU and the US. In May 2026 FDA proposed keeping it off the list of bulk substances that outsourcing facilities may compound from. WADA doesn’t prohibit it, though it is in the 2027 Monitoring Program. More on our page Semaglutide legal status.

FAQ

How well studied is semaglutide?

Far better than most substances people track. It has been tested in large randomized controlled trials, among them SUSTAIN-6 with 3,297 participants and SELECT with 17,604.

What side effects were seen in the trials?

Gastrointestinal effects such as nausea and diarrhea were the most common, and they were the main reason people stopped treatment. SUSTAIN-6 also found more diabetic eye complications, and a 2025 meta-analysis found more gallbladder problems.

Do the trial results apply to semaglutide bought online?

No. The trials used licensed products under medical supervision. FDA has warned about unapproved semaglutide sold as a research chemical and about salt forms that have no lawful basis.

Sources

  • Marso SP, et al. Semaglutide and cardiovascular outcomes in patients with type 2 diabetes (SUSTAIN-6). N Engl J Med. 2016;375:1834-44. PMID 27633186
  • Wilding JPH, et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). N Engl J Med. 2021;384:989-1002. PMID 33567185
  • Lincoff AM, et al. Semaglutide and cardiovascular outcomes in obesity without diabetes (SELECT). N Engl J Med. 2023;389:2221-32. PMID 37952131
  • Safwan M, et al. Gastrointestinal safety of semaglutide and tirzepatide vs. placebo in obese individuals without diabetes: a systematic review and meta analysis. Ann Saudi Med. 2025;45:129-43. PMID 40189856
  • FDA. FDA’s concerns with unapproved GLP-1 drugs used for weight loss. fda.gov
  • EMA. Union Register data: centrally authorised medicines containing semaglutide (first authorisation 8 February 2018). ema.europa.eu
  • EMA. Warning about sharp rise in illegal medicines sold in the EU (3 September 2025). ema.europa.eu
  • USADA. Athlete advisory: what’s new on the 2027 WADA Prohibited List? usada.org
  • WADA. WADA publishes 2027 Prohibited List (21 September 2026). wada-ama.org

Facts last checked: 16 October 2026.

About this article

Written by: the Pinnacle Pulse Editorial Team, the people who make the Pinnacle Pulse app. We work only from primary sources such as regulators, legal texts, trial registries and PubMed, and we remove claims we can’t check against one.

This article has not been reviewed by a physician. It is general information, not medical advice.

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Change log

  • 16 October 2026: First published.

From the makers of this site: Pinnacle Pulse is a neutral tracking app. We don’t sell or recommend any substance. About Pinnacle Pulse

This article is for general information only. It is not medical advice and does not recommend the use of any substance. Decisions about medicines belong with a qualified healthcare professional.