Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are injectable medications that treat type 2 diabetes.
Similar to insulin, they’re injected under the skin. GLP-1 RAs are most commonly used jointly with other antidiabetes treatments.
Currently, there are several GLP-1 RAs on the market that differ by dosing schedule and duration of action. They include:
- exenatide (Byetta)
- exenatide — extended release (Bydureon)
- dulaglutide (Trulicity)
- semaglutide (Ozempic) — also available in tablet form (Rybelsus)
- liraglutide (Victoza)
- lixisenatide (Adlyxin)
Pramlintide (Symlin) is another injectable drug approved for treatment of type 2 diabetes. It’s used in conjunction with mealtime insulin shots. Though less commonly used, it works similarly to GLP-1 RAs.
Unlike insulin and other antidiabetic drugs, injectables don’t cause weight gain.
Because they decrease appetite, they may even contribute to weight loss in the range of 3.3 pounds (1.5 kg) to 6.6 pounds (3 kg). The amount of weight loss depends on multiple factors, such as:
- use of other medications
Because of this, GLP-1 RAs are well suited for people who are overweight or have obesity. They’re often used in combination with other drugs or insulin to mitigate weight gain.
GLP-1 RAs are available in prefilled pens that you administer yourself, in much the same way as insulin. They differ by dosage and duration of action.
There are currently no comparative trials that show how choice of medication affects long-term patient outcomes.
Your doctor will usually start you off with a low dosage. This will be gradually increased according to tolerance and desired effect.
Byetta is the only agent that needs to be administered twice a day. The others are daily or weekly injections.
Gastrointestinal side effects, such as nausea, vomiting, and diarrhea, occur in many patients. Nausea may lessen over time or by lowering the dose. It may also occur less frequently with weekly agents.
Some reports link acute pancreatitis with GLP-1 RAs, but there’s not enough data to establish a clear causal relationship. Research has explored other potential adverse effects on the pancreas, such as pancreatic cancer, but insufficient evidence exists.
Some GLP-1 RAs may cause local skin reactions at the injection site. Some people using exenatide (Bydureon, Byetta) have reported this side effect.
Hypoglycemia rarely occurs with GLP-1 RAs when used alone. However, adding them to insulin-based therapies can increase risk.
In rodent studies, there was an increase in medullary thyroid tumors. A similar effect has not yet been found in humans.
Lifestyle changes for people with type 2 diabetes may consist of:
- modifying diet
- losing 5 to 10 percent of body weight, for those who have overweight or obesity
- regularly exercising for 150 minutes a week
- self-monitoring of blood sugars
- limiting alcohol to one drink per day for adult women and two drinks per day for adult men
- not smoking or quitting smoking
The diabetes plate method is commonly used for providing basic meal planning guidance and for its visual help.
Seeing a registered dietitian may also help lead you to a healthier diet. A dietitian can recommend an individualized nutrition plan that accounts for your specific factors and preferences.
In general, reducing your carbohydrate intake is necessary to improve blood sugar management.
Choose carbs that are:
- high in fiber
- minimally processed
Replace sugar-sweetened beverages with water.
Additionally, eating foods rich in monounsaturated and polyunsaturated fats might improve glucose metabolism and lower cardiovascular risk.
Injectable GLP-1 RAs and pramlintide (Symlin) are expensive. No generic options are currently available. Average wholesale prices are as follows:
- Exenatide: $840
- Dulaglutide: $911
- Semaglutide: $927
- Liraglutide: $1,106
- Lixisenatide: $744
- Pramlintide: $2,623
These are covered by many insurance plans. but policy guidelines, exclusions, requirements for step therapy, and prior authorization vary widely.
It’s important to become familiar with the specifics of your prescription drug plan.
Dr. Maria S. Prelipcean is a physician specializing in endocrinology and diabetes. She currently works at Southview Medical Group in Birmingham, Alabama. Dr. Prelipcean is a graduate of Carol Davila Medical School in Bucharest, Romania. She completed her internal medicine training at the University of Illinois and Northwestern University in Chicago and her endocrinology training at the University of Alabama in Birmingham. Dr. Prelipcean has been repeatedly named as a Birmingham Top Doctor and is a Fellow of the American College of Endocrinology. In her spare time, she enjoys reading, traveling, and spending time with her family.