GLP-1 medications are a group of medicines used to help manage type 2 diabetes and obesity. They help control blood sugar, support weight loss, and can lower the risk of heart and kidney problems and improve liver disease for some people. These medicines are usually given as injections or pills and work best when combined with healthy eating and regular physical activity.

GLP-1 medications are a class of medicines called glucagon-like peptide-1 receptor agonists. They act like a natural hormone in the body that helps control blood sugar and appetite—two key factors in managing diabetes and supporting weight loss.

The following GLP-1 medications are FDA-approved for use in the United States:

• Liraglutide (Saxenda, Victoza)
  For type 2 diabetes and for long-term weight management in adults and some adolescents with obesity or overweight along with at least one weight-related condition.
  (A weight-related condition is a health problem linked to excess weight, such as high blood pressure, high cholesterol, type 2 diabetes, prediabetes, fatty liver disease, or sleep apnea.)
• Semaglutide (Ozempic, Wegovy, Rybelsus)
  Ozempic and Rybelsus are approved for type 2 diabetes. Wegovy is approved for long-term weight management in adults and some adolescents with obesity or overweight and at least one weight-related condition. It is also approved for the treatment of metabolic dysfunction-associated steatohepatitis (MASH) in adults with moderate-to-advanced liver scarring as well as to lower the risk of heart attack, stroke, and death from heart disease in adults with heart disease and overweight or obesity.
• Dulaglutide (Trulicity)
  Approved for type 2 diabetes and shown to provide heart and kidney benefits.
• Tirzepatide (Mounjaro, Zepbound)
  Mounjaro is approved for type 2 diabetes. Zepbound is approved for long-term weight management in adults with obesity or overweight and at least one weight-related condition. It is also approved for the treatment of moderate-to-severe obstructive sleep apnea in adults with obesity.

Tirzepatide (Mounjaro/Zepbound) is sometimes discussed separately because it is a dual agonist. This means it activates both the GLP-1 receptor and the GIP (glucose-dependent insulinotropic polypeptide) receptor, a hormone pathway that helps the body release insulin after eating, which may lead to greater effects on blood sugar and weight loss compared to single GLP-1 agonists.

These medicines are available as injections given daily or weekly, and some (such as Rybelsus) are available as pills. GLP-1 medications are often used when diet, exercise, and other medicines have not provided enough benefit. Lifestyle changes, such as regular exercise and healthy eating, are central to the success of treatment.

GLP-1 medications help lower blood sugar and support weight loss by affecting several processes in the body.

• These medicines slow how quickly food leaves the stomach, helping people feel full and eat less.
• They prompt the pancreas to release more insulin when blood sugar is high, which helps move sugar from the bloodstream into the body’s cells, where it can be used for energy, thereby helping to lower blood sugar levels.
• GLP-1 medications also reduce the liver's production of glucose, which prevents the liver from adding extra sugar to the bloodstream when it is not needed.
• By acting on the brain, they decrease hunger and food cravings, making it easier to follow regular eating patterns and reduce overall calorie intake.
• Weight loss can help lower blood pressure and cholesterol, and research shows they can protect the heart and kidneys in certain people at higher risk.

GLP-1 medications may be recommended for:

• People with type 2 diabetes who need better blood sugar control. This includes those who:
• Have heart disease, kidney problems, or overweight
• Want to avoid weight gain or low blood sugar from other diabetes medicines
• People with overweight or obesity, including:
• Adults with a body mass index (BMI) of 30 or higher
• Adults with a BMI of 27 or higher and at least one weight-related health problem (such as high blood pressure or sleep apnea)
• Adults who have not met weight-loss goals with lifestyle changes alone
• Adolescents with obesity who qualify for certain GLP-1 medications

GLP-1 medications are not suitable for everyone. They should not be used by:

• People with a history of pancreatitis (inflammation of the pancreas)
• Anyone with a personal or family history of medullary thyroid cancer (a rare type of thyroid cancer)
• People with multiple endocrine neoplasia type 2 (MEN 2, a rare inherited condition that raises the risk of certain hormone-related tumors, including thyroid cancer)
• Women who are pregnant or breastfeeding
• People with severe stomach or bowel problems, such as gastroparesis (slow stomach emptying that causes nausea, fullness, or vomiting) or inflammatory bowel disease (chronic inflammation of the digestive tract, such as Crohn’s disease or ulcerative colitis)
• Those with severe kidney problems, especially with certain types of GLP-1 medicines, such as exenatide
• Anyone with allergies to GLP-1 medications or who has had a severe reaction to them

Use in children is limited to certain GLP-1 medicines approved for adolescents with obesity. Older adults may need dose adjustments or extra monitoring, especially if they have kidney problems or take other medicines. Doctors will review all health issues and medicines to ensure safe use.

People taking GLP-1 medications may experience a range of positive effects:

• Lower blood sugar levels, leading to improved diabetes control
• Promote weight loss, which can improve overall health and lower the risk of related medical problems
• Lower the risk of heart attacks, strokes, and kidney disease in people with diabetes or those at high cardiovascular risk
• Improve liver health in people with metabolic dysfunction-associated steatotic liver disease (MASLD)
• Help lower blood pressure and cholesterol, supporting overall heart health
• Reduce appetite and food cravings, making healthy eating patterns easier to maintain
• Less likely than some other diabetes medicines to cause low blood sugar or unwanted weight gain
• Can provide meaningful and lasting results for people who have struggled to lose weight with lifestyle changes alone

Certain lifestyle changes can help people get the most benefit from GLP-1 medications and reduce side effects:

• Adequate protein intake: Eating enough protein (such as fish, poultry, yogurt, beans, or tofu) at each meal helps maintain muscle while losing weight. If appetite is very low, protein shakes can be useful.
• Strength training: Regular strength training (such as using weights or resistance bands) two to three times per week helps minimize muscle loss and ensures that most weight lost is fat.
• Nutrient-dense foods: Eating a well-balanced, nutrient-dense diet with plenty of fruits, vegetables, whole grains, and healthy fats supports overall health and helps prevent vitamin and mineral deficiencies.
• Hydration: Drinking enough water and including water-rich foods (such as soups, cucumbers, and melons) can help prevent dehydration, which is important because GLP-1 medications may increase fluid loss.
• Physical activity: Regular aerobic exercise (such as brisk walking) and daily movement help maintain weight loss and support overall health.

Following these habits while taking GLP-1 medications can support healthy weight loss and help maintain muscle.

When starting GLP-1 medications, doctors usually begin with a low dose and increase it slowly over several weeks or months to reduce side effects, especially nausea and stomach upset. People may notice reduced appetite and some weight loss within the first few weeks, but it can take several months to see the full benefits for blood sugar and weight. The dose may be adjusted over time to find the amount that provides the best results with the fewest side effects.

GLP-1 medications are generally intended for long-term use and stopping them is not recommended without first speaking with a doctor. If the medication is stopped, weight regain and rising blood sugar can occur, as shown in clinical studies. Continuing healthy eating and physical activity can help maintain results, but most people need to stay on the medication long-term to keep its benefits.

Some people taking GLP-1 medications may experience digestive side effects, with these being the most common:

• Nausea, especially at the start or after a dose increase
• Heartburn or stomach discomfort after meals
• Constipation, which can occur as the body adjusts
• Diarrhea, which may be mild or bothersome
• Vomiting, sometimes along with nausea

Most digestive side effects lessen as the body adjusts; eating smaller meals and avoiding rich or spicy foods can help. If symptoms are persistent or troublesome, a health care provider may adjust the dose or suggest ways to ease them.

Less common but more serious risks include:

• Pancreatitis, which can cause severe abdominal pain and may require stopping the medication
• Gallbladder problems, such as gallstones or inflammation, especially with higher doses or longer use
• Allergic reactions, including swelling or difficulty breathing, which need immediate medical attention
• Injection site reactions, such as redness or itching, with injectable forms
• Rare vision changes or worsening diabetic eye disease, especially when blood sugar improves rapidly

Anyone with intense abdominal pain, signs of dehydration (such as dizziness or reduced urination), or unexpected vision changes should seek medical advice promptly.

GLP-1 medications can be used with other diabetes medicines, but there are special risks to consider:

• When GLP-1 medications are combined with insulin or medicines called sulfonylureas or meglitinides (which also lower blood sugar), the risk of low blood sugar (hypoglycemia) is higher. Doctors may lower the dose of these other medicines when a GLP-1 medication is started.
• GLP-1 medications should not be used together with DPP-4 inhibitors (medicines that increase natural GLP-1 levels) because this combination adds no extra benefit and may increase side effects.
• GLP-1 medications can be used with SGLT2 inhibitors (medicines that help the kidneys remove sugar from the blood), but monitoring for dehydration and other side effects is needed.

Always inform the care team about all prescription medicines, over-the-counter products, and supplements to avoid harmful interactions.

GLP-1 medications are usually given as injections under the skin, either once a day or once a week, depending on the specific medicine. Some newer GLP-1 medicines are available as pills taken by mouth once a day. Injections can be given in the abdomen, thigh, or upper arm.

The medicine may come in a prefilled pen or vial, and instructions are provided for safe use. People may need to learn how to give an injection themselves or how to take the pill correctly.

The choice between injection and pill depends on which medicine is prescribed, personal preference, and overall health needs.

Before starting GLP-1 medication, people should have a thorough medical evaluation. Doctors will review medical history, including any past problems with the pancreas, thyroid, or stomach. A physical exam may include checking the thyroid and the eyes, especially for people with diabetes.

Blood tests are often done to check kidney function and blood sugar levels. People should discuss all medicines they are taking, including over-the-counter and herbal products, to help avoid interactions.

Doctors may recommend a baseline eye exam for people with diabetes, especially before starting certain GLP-1 medicines. It is important to talk about any allergies or past reactions to medications. Women should mention if they are pregnant, breastfeeding, or planning to become pregnant.

Regular monitoring is important for people taking GLP-1 medication. Doctors will check:

• Blood sugar levels, usually every few months, to track how well diabetes is controlled
• Kidney function, especially in people with diabetes or those who may be at risk for dehydration
• Weight and blood pressure, to monitor progress and overall health
• Eye exams, especially for people with diabetes, to watch for any changes in vision
• Signs of pancreatitis, gallbladder problems, or allergic reactions, especially if new symptoms appear

People taking other diabetes medicines may need extra monitoring for low blood sugar. Doctors may adjust doses of insulin or other medicines as needed. It is important to report any new or severe symptoms to the care team.

“Yale Obesity Medicine has a truly integrated, team-based approach to weight management,” says Brian Wojeck, MD, MPH, a Yale Medicine endocrinologist with expertise in weight management. “Our patients are treated by nutritionists, mental health teams, culinary medicine in our teaching kitchen, bariatric surgeons, bariatric gastroenterology, sleep physicians, exercise physiologists, and obesity medicine specialists. Our researchers at Y-Weight have led the way in the field of obesity medicine and we integrate cutting-edge research into our constantly improving practice. Yale provides a unique and tailored approach to our complex patients.”