GLP-1 is a gut hormone that helps control blood sugar, reduce appetite, increase feelings of fullness and slow stomach emptying. Reviewed:. GLP-1 medicines mimic this hormone and are used mainly to treat type 2 diabetes and, at specific doses, obesity or overweight with related health conditions.
What is GLP-1?
GLP-1 stands for glucagon-like peptide-1. It is an incretin hormone released by the gut after you eat. GLP-1 communicates with the pancreas, stomach and brain to help regulate blood glucose and food intake.
GLP-1 is broken down quickly by the body. GLP-1 receptor agonists, including semaglutide, liraglutide and dulaglutide, last longer and activate the same receptor.
How does GLP-1 affect blood sugar?
GLP-1 medicines lower blood sugar in three main ways:
| Effect | What it does |
|---|---|
| Increases insulin release | GLP-1 helps the pancreas release more insulin when blood glucose is elevated. |
| Reduces glucagon | GLP-1 lowers the release of glucagon, a hormone that signals the liver to release glucose. |
| Slows stomach emptying | GLP-1 can slow the movement of food from the stomach into the small intestine. This can reduce the speed of blood glucose increases after a meal. |
GLP-1 medicines stimulate insulin in a glucose-dependent way. When used alone, they generally have a lower risk of hypoglycemia than medicines that increase insulin regardless of blood sugar. The risk can rise when a GLP-1 medicine is combined with insulin or certain other diabetes drugs.
How does GLP-1 help with weight loss?
GLP-1 medicines can support weight loss by changing hunger and eating behavior. They may:
- Reduce appetite
- Increase fullness after eating
- Reduce food intake
- Slow stomach emptying, particularly early in treatment
- Affect brain pathways involved in appetite and satiety
GLP-1 medicines do not directly "burn fat." Weight loss usually occurs because a person feels less hungry and consumes fewer calories over time. The amount of weight lost varies by the medicine, dose, treatment duration and individual response.
What are GLP-1 medications used for?
Depending on the medicine and dose, GLP-1 receptor agonists may be prescribed to:
- Improve blood sugar control in people with type 2 diabetes.
- Support chronic weight management in people with obesity.
- Support weight management in people who are overweight and have a weight-related condition.
- Reduce certain cardiovascular risks for eligible people taking specific medicines, such as semaglutide.
Examples include:
- Semaglutide: Ozempic, Wegovy and Rybelsus
- Liraglutide: Victoza and Saxenda
- Dulaglutide: Trulicity
Tirzepatide, sold as Mounjaro and Zepbound, is often grouped with GLP-1 drugs. Technically, it is a dual GIP and GLP-1 receptor agonist because it acts on two hormone pathways.
What side effects can GLP-1 medications cause?
GLP-1 medicines most often cause gastrointestinal side effects, including:
- Nausea
- Vomiting
- Diarrhea
- Constipation
- Abdominal discomfort
- Reduced appetite
These effects partly reflect changes in appetite, digestion and stomach emptying. Severe or persistent vomiting can cause dehydration. Rare but serious problems can include pancreatitis, gallbladder disease, kidney problems and severe gastrointestinal reactions.
People with a personal or family history of medullary thyroid cancer or multiple endocrine neoplasia syndrome type 2 may be advised not to use certain GLP-1 medicines. Suitability depends on the specific medicine and the person's medical history.
What GLP-1 does not do
GLP-1 medicine is not insulin, does not cure diabetes and does not guarantee weight loss. It also does not replace nutrition, physical activity or medical monitoring.
Do not combine it with another GLP-1 medicine unless a prescriber tells you to do so. GLP-1 medicines are prescription treatments, and a clinician should select the medicine, check for contraindications and adjust the dose gradually when appropriate.