Tucson Region

Gila monster spit aids diabetics

Millions of diabetes sufferers throughout the world can thank the most unlikely of all medical heroes - our desert-dwelling Gila monster - for a new and effective drug to control their disease. Just given federal approval, the drug - marketed as Byetta - is made from the saliva of the slow-moving, venomous lizard of the American Southwest. "Well, it's weird. You have to wonder how you can go from Gila monster saliva to something that works in humans," said Sandra Leal, a pharmacist and diabetes expert at El Rio Community Health Center. "But when we explain it to patients, we talk about how infrequently Gila monsters eat, and how this chemical helps them digest meals slowly over time. That's very advantageous for controlling diabetes." With nearly 200 million people battling diabetes worldwide, the disease is reaching epidemic levels in the United States, where some 18 million now have it. Southwestern states with high minority populations, including Arizona, are especially hard hit, with diabetes rates running two to 10 times higher than in the rest of country. More than 90 percent of all diabetics struggle with the Type 2 form - in which the body does not produce enough insulin to control blood sugar, a condition often linked to being overweight or obese. Byetta - a new class of diabetes drug - has proved not only able to control blood sugar for longer periods of time than older diabetes drugs, but also to decrease appetite, leading to weight loss. "When people hear that, that's a big seller," Leal said. "It helps overcome the drug's one disadvantage - that it has to be injected. People are often resistant to having to give themselves a shot." But before anyone heads out to the desert to kiss a Gila monster for diabetes relief, bear in mind that this drug - known scientifically as exenatide - was not discovered by someone who was bitten by this lizard. Far from it. "In fact, the first time I ever saw a Gila monster was last year, when they flew me out to Portal (in Southeastern Arizona) to see the real thing," said Dr. John Eng, an endocrinologist at the Bronx Veterans Affairs Medical Center in New York City. Eng is credited with discovering exenatide after working on it for nearly two decades before ever laying eyes on the beast. "It is a beautiful reptile. All I can say is, without the Gila monster, this would never have happened, and to me, that is kind of humbling," he said. "I've come to really appreciate the Gila monster, and I don't want to see it disappear. I know it's under pressure from all the development out there, so please make sure the Gila monsters are well taken care of in Arizona." The road from Gila monster venom to diabetes drug was a long and scientifically complicated one that required "a lot of luck," Eng said. Since the early 1980s, Eng has specialized in research aimed at detecting new hormones in the human body. He started following up on earlier studies that found that humans who were bitten by venomous animals often developed a condition called pancreatitis, or inflammation of the pancreas - the organ that produces insulin, the hormone that controls blood sugar. "The theory was that the venom somehow overstimulates the pancreas," Eng said. "So we ordered up a whole variety of venoms, from snakes and other animals - one was the Gila monster - and started looking for the compounds that stimulated the pancreas." After years of laboratory research, Eng found that a compound isolated and purified from Gila monster saliva acted very much like a human pancreatic hormone that triggers the release of insulin when blood sugar rises too high. And once the compound was synthesized, he found it lasted longer in the body than the human hormone and other diabetes drugs. "So, the advantages are the longer duration of control, for many more hours, and the fact that it acts only when blood sugar is high," Eng said. "The older drugs act even when blood-sugar levels are near normal, sometimes lowering levels too far, which can be dangerous. That doesn't happen with exenatide." At this point, the new drug is to be prescribed for Type 2 diabetics whose blood sugar is not adequately controlled by the standard oral diabetes drugs - metformin and a sulfonylurea. However, the U.S. Food and Drug Administration is considering it as a possible stand-alone therapy. Byetta, developed by Amylin Pharmaceuticals and Eli Lilly, is due to be in U.S. pharmacies by June 1, officials said. "I have to say I'm thrilled this drug has proven successful," Eng said. "I want to thank the Gila monster."