What is GLP-1? Understanding Glucagon-like peptide-1

In 2019, about 21,000 people in the U.S. without type 2 diabetes used glucagon-like peptide-1 (GLP-1) medication to help manage obesity. By 2023, that number had grown exponentially. Conversations surrounding the increased use of GLP-1s often center around brand names like Ozempic or Wegovy, but there’s a lot more to learn about GLP-1 medication. Here’s how they work, who they might benefit and some of the different types available.

In this article:

How do GLP-1 medications work?

GLP-1 agonists are used to help manage type 2 diabetes and obesity as well as a few other conditions. They work by imitating GLP-1, a hormone produced in response to food intake. Because different GLP-1 agonists have different FDA-labeled indications, they may be used for different reasons, such as type 2 diabetes or weight loss.

GLP-1 for weight loss

The GLP-1 hormone has multiple effects on the body that contribute to its weight loss function: It targets areas of the brain that can help regulate appetite by working on the brain's appetite center and it slows down movement of food through the gut, enhancing feelings of fullness. All GLP-1 agonists labeled for weight reduction in cases of obesity or overweight plus one weight-related comorbidity must be combined with a reduced-calorie diet and increased physical activity.

GLP-1 for diabetes management

GLP-1 also helps trigger the release of insulin when blood sugar is high. Insulin usually helps regulate blood glucose levels, but in type 2 diabetes, this process can be impaired. GLP-1 medications can help to pick up the slack, helping the body respond to high blood sugar by supporting the release of insulin.

Effects of GLP-1 medication on the body

GLP-1 medications can help regulate blood sugar and slow gastric emptying — which may help promote a feeling of fullness and reduced appetite. Weight loss may also help lower blood pressure and improve cholesterol levels, which could decrease the risk of heart disease and other cardiovascular problems.

Managing blood sugar can help support kidney function, too — so much so that in January 2025, the U.S. Food and Drug Administration (FDA) officially approved the GLP-1 medication Ozempic to help reduce the risk of worsening kidney disease in adults with type 2 diabetes and chronic kidney disease.

GLP-1 medication side effects

While GLP-1 medications have many possible benefits, there are some potential side effects to watch out for. They may occur when patients start a GLP-1 agonist or increase their dose, and some can go away on their own over time. These may include but are not limited to:

• Constipation
• Diarrhea
• Nausea
• Vomiting

In some cases, GLP-1 medications may cause serious reactions, such as pancreatitis or vision changes. In these situations, a health care provider may decide it’s best to stop treatment altogether. Patients should seek help immediately about any side effects that are severe or do not go away.

Some types of GLP-1 medications

Many GLP-1 medications are available in injectable form. Some are available as a pill. Some of the GLP-1 based medications available on the U.S. market include:

• Dulaglutide injections (common brand name: Trulicity)
• Liraglutide injections (common brand names: Saxenda and Victoza)
• Semaglutide injections (common brand names: Ozempic and Wegovy)
• Semaglutide tablets (common brand name: Ozempic, Rybelsus and Wegovy)
• Orforglipron tablets (common brand name: Foundayo)
• Tirzepatide (GLP-1/GIP receptor agonist) injections (common brand names: Mounjaro and Zepbound)

Who might benefit from weight-management medication?

Prescription weight-management medications may be used (in combination with a reduced-calorie diet and increased physical activity) for people with one of the following conditions:

• A body mass index (BMI) of 30 or higher
• A BMI of 27 or higher with a weight-related condition, such as high blood pressure or type 2 diabetes

GLP-1s and weight-management medications may also be prescribed for reasons outside of this list.

Who should not take GLP-1 medications?

GLP-1 medications are not recommended for people with a personal or family history of medullary thyroid carcinoma (MTC) or multiple endocrine neoplasia syndrome type 2 (MEN 2). They should also be avoided by individuals with a history of severe allergic reactions to these medications.

People with a history of pancreatitis should use caution. Pregnant or breastfeeding women should not take GLP-1 medications. A health care provider should help patients determine if these medications are appropriate for them.

What can happen when people stop taking GLP-1 medications?

The effects of GLP-1 medications may not be permanent. While they may help create healthier habits, some weight may be regained if treatment is stopped. Most people may end up regaining some of the weight that they lost.

Key takeaways

• GLP-1 (glucagon-like peptide-1) is a naturally occurring hormone that helps reduce appetite, regulate blood sugar levels and slow digestion.
• GLP-1 medications, also called GLP-1 receptor agonists, mimic this hormone to help manage type 2 diabetes and support weight loss in people who are overweight or have obesity.
• These medications work by stimulating insulin release when blood sugar is high, slowing stomach emptying and reducing hunger signals in the brain.
• Potential side effects of GLP-1 medications include nausea, vomiting, diarrhea and constipation, which may improve over time. If someone is experiencing side effects, it is important to have them reach out to a health care provider.
• Weight management with GLP-1 medications often requires ongoing treatment; stopping their use without sustained lifestyle changes may lead to regained weight.