Glucagon-like peptide-1 receptor agonist (GLP-1 RA) drugs are medications used to manage certain health conditions. They work by interacting with specific receptors in the body, leading to various physiological effects. Understanding how these medications function, the conditions they address, their available forms, and potential considerations is important for individuals seeking information about them.
How GLP-1 Receptor Agonists Work
GLP-1 receptor agonists function by mimicking the actions of a natural hormone called glucagon-like peptide-1. This hormone is normally released from the gut in response to food intake. Once released, GLP-1 travels to the pancreas, signaling it to increase insulin secretion when blood sugar levels are elevated. This glucose-dependent insulin release helps to lower blood glucose.
Beyond stimulating insulin, GLP-1 also suppresses the release of glucagon, another hormone produced by the pancreas. Glucagon raises blood sugar by signaling the liver to release stored glucose. By reducing glucagon levels, GLP-1 receptor agonists help prevent excessive glucose production. Additionally, these medications slow down the rate at which food leaves the stomach, a process known as gastric emptying. This slower emptying helps to prevent sharp spikes in blood sugar after meals and contributes to a feeling of fullness. The impact on gastric emptying, combined with direct effects on brain centers that regulate appetite, can lead to reduced food intake and an increased sense of satiety.
Conditions Treated by GLP-1 Receptor Agonists
GLP-1 receptor agonists are primarily prescribed for Type 2 Diabetes Mellitus. They improve glycemic control by lowering hemoglobin A1C levels, a measure of average blood sugar over two to three months, by enhancing glucose-dependent insulin secretion and suppressing glucagon. These drugs are also approved for weight management in certain individuals, including those with obesity or overweight with at least one weight-related condition. Their effects on satiety and delayed gastric emptying contribute to reduced caloric intake and weight loss. Additionally, some GLP-1 receptor agonists have demonstrated cardiovascular benefits, including a reduced risk of major adverse cardiovascular events in people with Type 2 Diabetes and established cardiovascular disease.
Forms and Administration
GLP-1 receptor agonists are available in both injectable and oral forms. Many are administered via subcutaneous injection, just under the skin. Some injectable forms require daily administration, while others are designed for once-weekly use, providing convenience for patients.
Examples of injectable GLP-1 receptor agonists include liraglutide, administered once daily, and semaglutide and dulaglutide, given once weekly. An oral form of semaglutide is also available, providing a non-injectable alternative. Another medication, tirzepatide, functions as both a GLP-1 and glucose-dependent insulinotropic polypeptide (GIP) receptor agonist, and is administered as a once-weekly injection.
Potential Side Effects and Important Considerations
Individuals taking GLP-1 receptor agonists may experience various side effects, with gastrointestinal issues being the most common. These often include nausea, vomiting, diarrhea, or constipation. These symptoms are typically mild to moderate and may lessen over time as the body adjusts to the medication. To help manage these effects, healthcare providers often recommend starting with a low dose and gradually increasing it.
Less common but more serious concerns associated with GLP-1 receptor agonists include pancreatitis (an inflammation of the pancreas) and gallbladder issues, such as gallstones. There have also been observations of thyroid C-cell tumors in rodent studies, though the relevance of these findings to humans is not yet established. Individuals with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2) are typically advised against using these medications. Close medical supervision is important throughout treatment, and patients should report any unusual symptoms to their healthcare provider.