What is GLP-1, Glucagon Like Peptide-1

What is the GLP-1 Hormone and where does it come from?

GLP-1 (Glucagon-like peptide-1) is a naturally occurring incretin hormone made in the intestine in response to food. GLP-1 is one of the two most important incretins—hormones that stimulate insulin secretion in response to a meal. But GLP-1 does more than simply increase insulin secretion. In fact, it has several important roles in the body. They can be summarized into two main functions.

GLP-1 affects levels of insulin and glucagon to decrease elevated blood sugar levels in two ways:

GLP-1 increases the body’s own natural insulin secretion in response to a meal.
GLP-1 lowers levels of the hormone glucagon after eating. Glucagon works opposite insulin and raises blood sugar levels, so deceasing glucagon levels helps to lower blood sugar.

GLP-1 increases satiety or makes an individual feel full

GLP-1 slows stomach emptying, so food is delivered more slowly to the intestines to continue digestion. If the food is digested more slowly, carbohydrate absorption is prolonged.
GLP-1 suppresses appetite in the brain’s hunger center (hypothalamus).

GLP-1 in a person without diabetes

GLP-1 in a person with diabetes

What is a GLP-1 analog/agonist?

GLP-1 analogs or agonists act like naturally occurring GLP-1 by stimulating the same receptor as a person’s own GLP-1 hormone. Rewind the clocks back to the early 1990s, when an endocrinologist discovered a special molecule similar to human GLP-1, which was being studied around the same time. Dr. John Eng found this special protein in the last place you could imagine—the saliva of the Gila monster, a poisonous lizard. This substance, called exendin-4, is 53% similar to human GLP-1 hormone, but is more resistant to being broken down. This makes it more useful as a treatment option. Scientists reproduced exendin-4 in the lab, calling it exenatide. Exenatide was first made available for type 2 diabetes management in 2005 as Byetta®, a twice-daily injection.

GLP-1 levels and type 2 diabetes

Turns out that patients with diabetes are not only likely deficient in their own GLP-1 hormone but, more importantly, the cells that make insulin are resistant to stimulation by GLP-1. This means patients might have less of this important hormone, and what they have left clearly does not stimulate insulin as well.

Why not just treat patients with the GLP-1 hormone?

The body’s own naturally occurring GLP-1 has a very short half-life in the bloodstream. Within minutes, hormones like DPPIV break down GLP-1. Due to this rapid degradation, treating patients with GLP-1 hormone directly has never been shown to be a useful option.

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Last Modified: Aug 15, 2020 @ 5:33 pm

About the Author

Chris Palmeiro D.O. M.Sc.

Dr. Christopher Palmeiro serves as the Medical Director of Telehealth for Moonlighting Solutions. He is also the Medical Director of the Inpatient Endocrinology Telemedicine Program at Atlanticare Regional Medical Center in Southern New Jersey. Additionally, Dr. Palmeiro serves Native American patients, in the Midwestern United States, via the Avera E-Care Specialty Telemedicine platform. Prior to his current positions, Dr. Palmeiro completed his fellowship in endocrinology, diabetes, and metabolism at Westchester Medical Center. He completed both his residency and chief residency in internal medicine at St. Vincent’s Catholic Medical Center in Manhattan. He is a diplomate of the American Board of Internal Medicine. Dr. Palmeiro completed a Master of Science degree in clinical nutrition while in medical school at New York Institute of Technology College of Osteopathic Medicine and was the first graduate of an innovative program that incorporated this degree into the medical school curriculum, earning him the John J. Theobald Graduate Achievement award.