The GLP-1 story

• How semaglutide was engineered from native GLP-1 into a once-weekly peptide
• The incretin biology behind its glucose, appetite, and gastric-emptying effects
• How to read the STEP, SUSTAIN, PIONEER, SELECT, and FLOW trial evidence honestly
• How it compares to tirzepatide and liraglutide, and where the safety limits sit

1. 01 The GLP-1 story How a gut hormone became a once-weekly metabolic medicine free
2. 02 GLP-1 and incretin biology The incretin system semaglutide borrows from paid
3. 03 Molecular engineering How a handful of changes turned GLP-1 into a once-weekly drug paid
4. 04 Type 2 diabetes control Glycemic control across the SUSTAIN and PIONEER programs paid
5. 05 Weight management STEP trials, real magnitude, and the regain problem paid
6. 06 Cardiovascular outcomes From surrogate markers to hard heart outcomes paid
7. 07 Kidney and liver Protecting the kidneys and treating fatty liver paid
8. 08 Versus other agents Semaglutide against tirzepatide and liraglutide paid
9. 09 Safety & Side Effects What is common, what is serious, and what is contraindicated paid
10. 10 Dosing & Administration How semaglutide is prepared, titrated, and administered paid
11. 11 Regulatory & compounding Approved products, compounding, and quality control paid
12. 12 Final Exam & Certification Pass the final exam to earn your certificate of completion. Exam

Semaglutide did not arrive all at once. It reached the clinic as a diabetes drug, then steadily earned new indications as the outcome trials read out, one population at a time. Tracing that timeline shows how the evidence, not the marketing, expanded what the molecule is approved to do, moving from glucose control into weight, heart, kidney, and liver disease, and from the pen into a pill, across its first nine years.

Strip away the brand names and semaglutide is one peptide: a long-acting analog of human GLP-1. Native GLP-1 is destroyed within minutes by an enzyme, so it was useless as a standalone drug. Semaglutide keeps almost all of the natural sequence but is rebuilt to survive in the bloodstream for about a week, which is the single fact that makes once-weekly dosing possible. The peptide chain itself is 31 amino acids long.

The same active ingredient is sold under a small set of brand names with different doses, routes, and approved uses. Knowing which is which prevents a common confusion: Ozempic and Wegovy are the same peptide at different dose ranges and for different indications. What no longer separates them is the route. Oral Wegovy (semaglutide 25 mg tablets) and Ozempic-branded tablets were both added in the years since, so both brands now exist as a weekly injection and as a daily tablet. Rybelsus, the original oral brand, shares one prescribing information with the Ozempic tablets, though Novo Nordisk says it is transitioning US patients to the Ozempic tablet while Rybelsus continues to be marketed outside the US. Each is a prescription medicine, not an over-the-counter supplement, and each carries its own indications and labeling that should never be assumed to transfer freely between the products. That caution now applies inside a brand as well as between brands: the Wegovy injection and the Wegovy tablet share a label document but not an indication set, and treating Wegovy as one product with one list of approved uses is the most common mistake left in the marketing copy.

Semaglutide works by switching on the GLP-1 receptor in several tissues at once. The receptor is not just a diabetes switch: it touches the pancreas, the brain, and the gut, which is why one peptide affects glucose, appetite, and digestion together. This page is the high-level map; the next unit goes deeper into each pathway and how they reinforce one another.

Before the deep dives, here is the honest picture: what is genuinely well-supported versus what is still uncertain. Semaglutide is unusual among peptides in that its strongest claims rest on large randomized trials, but even here some questions, like durability after stopping, remain genuinely open. Keeping these four tiers apart, rather than collapsing them into one slogan, is what separates honest education from marketing copy.

Plenty of confident claims circulate online. Held against the trial evidence, most are not flatly false so much as overstated or stripped of their context. Learning to match each claim to its real evidence tier is the core skill this course builds, and it is what lets you read a confident online headline and ask the one follow-up question that usually deflates it.