GLP-1 agonists

HOW GLP-1 AGONISTS WORK

Glucagon-like peptide-1 (GLP-1) is a natural hormone that is released by your gut after a meal. The hormone GLP-1:

• Signals to your brain that you are full
• Tells your pancreas to release insulin, which helps regulate blood sugar
• Slows down how quickly your stomach empties

GLP-1 agonists are man-made (synthetic) hormones that cause many of the same actions as natural hormones. They enhance these natural processes within the body. The higher the dose, the more the effect.

GLP-1 agonists were first developed to help people with type 2 diabetes control their blood sugar. These medicines also lead to weight loss because they:

• Reduce your appetite
• Reduce food cravings
• Slow digestion so you feel fuller for longer

GLP-1 agonists alone cannot treat diabetes or obesity. They work best when used along with lifestyle changes such as a healthy diet and regular exercise.

Many people using GLP-1 agonists will regain lost weight if they stop taking the medicine.

GLP-1 agonists also may help reduce the risk of serious heart problems such as heart attack and stroke. They improve kidney disease in some people with type 2 diabetes. Some GLP-1 agonists have proven positive effects on obstructive sleep apnea and knee osteoarthritis. Other possible benefits of GLP-1 agonists continue to be discovered, including a possible benefit for people with type 1 diabetes.

TYPES OF GLP-1 AGONISTS

GLP-1 agonists are most often given as an injection either daily or weekly. One type is taken as a pill. GLP-1 agonists approved for the treatment of type 2 diabetes include:

• Dulaglutide (Trulicity): Injection; once a week
• Exenatide (Byetta): Injection; twice a day
• Liraglutide (Victoza): Injection; once a day
• Lixisenatide (Adlyxin): Injection; once a day
• Semaglutide (Ozempic): Injection; once a week
• Tirzepatide (Mounjaro): Injection; once a week
• Semaglutide (Rybelsus): Pill; daily

Dulaglutide and liraglutide are also approved for treatment in people with type 2 diabetes and heart problems to reduce the risk of serious cardiac events.

GLP-1 agonists approved for the treatment of obesity include:

• Semaglutide (Wegovy): Injection (once a week), or pill (once a day)
• Tirzepatide (Zepbound): Injection; once a week

POSSIBLE SIDE EFFECTS

GLP-1 agonists can have some side effects. Most of the side effects occur with a higher dose, and get better with time as the body adjusts to treatment.

Side effects may include:

• Nausea
• Vomiting
• Diarrhea
• Abdominal pain
• Loss of appetite
• Constipation
• Headache
• Low blood sugar (higher risk if taken along with insulin or sulfonylureas)
• Reduced muscle mass
• Injection site reactions, such as rash or itching
• Pancreatitis (rare)
• Gallbladder disease (rare)

Contact your health care provider if any side effect bothers you.

GLP-agonists are not recommended for:

• Pregnant women
• People with a history of medullary thyroid cancer
• People with a family history of multiple endocrine neoplasia, type II (MEN II)

WHEN TO CONTACT A MEDICAL PROFESSIONAL

Call 911 or the local emergency number if you experience:

• Severe allergy (anaphylaxis) symptoms such as breathing or swallowing difficulty, chest tightness, or hives.
• Low blood sugar symptoms such as dizziness, trembling, extreme tiredness, and fast heart rate.

GLP-1 receptor agonists; GLP-1 analogs; Incretin mimetics; GLP-1 RAs; Glucagon-like peptide-1 agonists

Ahmann AJ, Riddle MC. Therapeutics of type 2 diabetes mellitus. In: Melmed S, Auchus, RJ, Goldfine AB, Rosen CJ, Kopp PA, eds. Williams Textbook of Endocrinology. 15th ed. Philadelphia, PA: Elsevier; 2025:chap 34.

Dhatariyan KK, Umpierrez GE, Crandall JP. Diabetes mellitus. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 210.

Jensen MD, Bessesen DH. Obesity. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 201.

Moiz A, Filion KB, Tsoukas MA, Yu OH, Peters TM, Eisenberg MJ. Mechanisms of GLP-1 receptor agonist-induced weight loss: a review of central and peripheral pathways in appetite and energy regulation. Am J Med. 2025 Jun;138(6):934-940. Epub 2025 Jan 31. PMID: 39892489.  pubmed.ncbi.nlm.nih.gov/39892489/.

Moiz A, Filion KB, Tsoukas MA, Yu OHY, Peters TM, Eisenberg MJ. The expanding role of GLP-1 receptor agonists: a narrative review of current evidence and future directions. EClinicalMedicine. 2025 Jul 17;86:103363. PMID: 40727007; PMCID: PMC12303005. pubmed.ncbi.nlm.nih.gov/40727007/.

Orandi BJ, Aronne LJ. Obesity. In: Chung RT, Rubin DT, Wilcox CM, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 12th ed. Philadelphia, PA: Elsevier; 2026:chap 8.

Updated by: Sandeep K. Dhaliwal, MD, board-certified in Diabetes, Endocrinology, and Metabolism, Springfield, VA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.