It won’t take you long to realize that poking that Gila monster with a stick wasn’t a good idea. But when you go to the doctor to get the bite treated—and possibly the teeth extracted from your leg—refrain, for a moment, from cursing the whole species. According to studies at the School of Medicine, a hormone in that Gila monster’s saliva (or something very much like it) is benefiting a lot of people.

Click to read photo caption. Photo by Jon Davis, ©2007 Endeavors.

In its saliva, the Gila monster secretes a hormone called exendin-4, which scientists have spun into a new drug that improves blood-sugar control and induces weight loss in people with diabetes. Exendin-4 is remarkably similar to a human hormone called GLP-1 (glucagon-like peptide-1) which stimulates insulin production when a person has high blood sugar. GLP-1 slows the emptying of the stomach to reduce appetite and make you feel full, says John Buse, UNC Chief of Endocrinology.

The new drug, called exenatide, is a synthetic version of exendin-4 (the lizard hormone). But why not just make more GLP-1? “GLP-1 is known to rapidly degrade in the body,” says Buse, who completed a three-year study of the drug with patients who have type 2 diabetes. “That made it hard to produce a convenient drug. But exendin-4 has properties that make it long-lasting.” And it’s easier to make in bulk in the lab.

Weight gain and being overweight are pervasive problems among people with type 2 diabetes, Buse says. And insulin injections—currently the most commonly prescribed medication for diabetes—can cause more weight gain, which can, in turn, worsen some aspects of the disease. But after taking exenatide for three years, most patients in Buse’s study had achieved healthy, sustained glucose levels and had lost an average of eleven pounds—quite an accomplishment, especially for patients who had trouble losing weight despite proper diet, exercise, and help from other medications.

Venom and blood sugar

But what about the Gila monsters? Where did that connection come from? Well, it turns out that toxic venom from these lizards—and lots of other venomous animals—can give victims pancreatitis. John Eng, an endocrinologist at the Bronx Veteran Affairs Medical Center in New York City, was looking at studies of those victims and trying to find out why and how the venom affected the pancreas, which controls blood sugar by releasing insulin. So Eng ordered a bunch of different animal venoms, including the Gila monster’s, and voilà: exendin-4.

The only drawback: patients who take Byetta (exenatide’s commercial name) are on it for the long haul. Patients have to self-inject the drug twice a day, and stay on it even after they have lowered their blood sugar and reached a healthy weight, Buse says. “If they stop the drug,” he says, “the assumption is that they’ll slide back to where they were before.”