Every time you eat, an unseen drama unfolds inside your body: Hormones called incretins race from the gut to the pancreas and tell that organ to produce more insulin. But just as soon as an incretin goes to work, a killer enzyme gives chase, bent on its annihilation.

Understanding that natural process—plus a timely discovery about lizard venom (more on that later)—has led scientists to develop some of the newest diabetes medications. These meds, including exenatide (Byetta), sitagliptin (Januvia), and, most recently, saxagliptin (Onglyza), all use the incretin system to lower blood glucose in people with diabetes.

And they may be just the beginning. At least half a dozen more incretin-based medications are in line to seek Food and Drug Administration approval. Here’s a look at the inner workings of the body that make these meds possible.

The Incretin System
Even before food hits the stomach, incretins are released from specialized cells in the small intestine into the bloodstream. As a meal is broken down and blood glucose levels increase, the incretins stimulate the pancreas to produce insulin, which brings blood glucose back down.

Researchers used to believe that insulin was released in direct response to increasing blood glucose levels. But then they noticed an odd thing: Injecting glucose into the bloodstream doesn’t raise insulin levels as much as giving the same amount of glucose by mouth. The scientists reasoned that some messenger—an incretin—must go between the digestive tract and the pancreas to tell it to step up insulin production.

There isn’t just one type of incretin, but the most significant for people with diabetes is called glucagon-like peptide-1. GLP-1 should not be confused with glucagon itself; they have very different functions (glucagon is a hormone that increases blood glucose). “GLP-1 is your natural anti-diabetic hormone,” explains Patricia Brubaker, PhD, a professor at the University of Toronto who studies incretins.

Research has shown that people with type 2 diabetes don’t have enough incretins, which could exacerbate the problem of high blood glucose. Studies suggest that one reason bariatric surgery may help people with diabetes is that, in addition to causing weight loss, it seems to stimulate incretin production.

GLP-1 has more responsibilities in the body than simply facilitating insulin release. “GLP-1 suppresses glucagon and it reduces appetite, which is associated with weight loss,” says Brubaker, adding that the incretin may also improve heart health by lowering cholesterol and triglyceride levels in the blood.