Semaglutide

Semaglutide is a synthetic 31-amino-acid peptide modelled on human glucagon-like peptide-1 (GLP-1). Two modifications matter: a change that stops the enzyme DPP-4 from breaking it down quickly, and a side chain that lets it ride along on albumin in the blood. The result is a half-life of roughly one week, which is why it is dosed weekly. It is a prescription medicine (Ozempic, Wegovy, Rybelsus).

1. 1

   After injection it binds GLP-1 receptors on cells in the pancreas, gut, and appetite centres of the brain.

2. 2

   In the pancreas it increases insulin release and reduces glucagon release, but mainly when blood glucose is already high — which is why it rarely causes hypoglycaemia on its own.

3. 3

   It slows gastric emptying, so nutrients reach the small intestine over a longer period.

4. 4

   It signals the hypothalamus to reduce hunger and food intake.

5. 5

   Together these lower blood glucose and body weight.

• HbA1c reduction of roughly 1.5 percentage points in randomised trials
• About 15% mean weight loss at 68 weeks with the 2.4 mg weekly dose (STEP 1)
• Fewer major cardiovascular events in adults with diabetes at high cardiovascular risk
• Slower gastric emptying and measurably reduced appetite
• Reduced liver fat in imaging sub-studies

1. 01Wilding et al., Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1), NEJM 2021
2. 02Marso et al., Semaglutide and Cardiovascular Outcomes in Patients with Type 2 Diabetes (SUSTAIN-6), NEJM 2016
3. 03European Medicines Agency — Ozempic product information
4. 04European Medicines Agency — Wegovy product information

References link to published literature, regulator pages or literature indexes. Where a link points to a search, it collects the peer-reviewed work on that molecule rather than a single study.