Insulin is not the only injectable product available to treat diabetes. Glucagon-like peptide 1 (GLP-1) related medications are also available as subcutaneous injections to improve glucemic control and also have a beneficial potential side effect of weight loss.
Byetta® (Exenatide) is presently the only injectable GLP-1 related medication on the market in the United States; however, numerous others are in clinical trials at this time and Victoza®(Liraglutide) has been approved in Europe as a once daily injection and is being reviewed by the FDA at this time. Byetta® is indicated for use in people with type 2 diabetes mellitus who are taking other oral medications to treat diabetes but have not achieved adequate glucose control. GLP-1 occurs naturally and is released from the intestine when nutrients are present. It then stimulates insulin secretion from the pancreas and inhibits the release of glucagons, both of which cause glucose levels to decrease. Byetta® is presently given by twice daily subcutaneous injection, using a pen device; however, a once weekly injection may be available in the next few months. Though injecting Exenatide is identical to insulin delivery methods, Byetta® is very unlike insulin in its dosing. It comes in only two doses—5 and 10 micrograms—while insulin dosing is nearly infinite, with almost every patient having a different dose. GLP-1 related treatments help to lower glucoses and have been shown to promote weight loss. They work in five ways to accomplish this:
- Signaling the pancreas to release insulin
- Stopping the liver from making glucoses
- Slowing how quickly the stomach empties food and glucose which helps to keep glucose levels lower after eating and causes you to feel full after a small meal
- Telling the appetite center in the brain you are full
- Decreasing the body’s production of glucagon (a hormone that raises glucose level)
Hypoglycemia is NOT a side effect of GLP-1 therapy. If hypoglycemia occurs, it is most likely due to the sulfonylurea medication you may also be taking, such as
- Glipizide
- Glimepiride
- Glyburide
As we already discussed, weight loss is a common therapeutic effect of GLP-1 treatment. The potential weight loss and the lack of hypoglycemia make this a very attractive treatment option; I commonly attempt this therapy before moving on to insulin. The most common side effects are gastrointestinal in origin and include:
- Nausea
- Vomiting
- Diarrhea
This therapy should not be used in people with:
- Reduced kidney function
- Certain gastrointestinal problems
