PHOENIX -- The Gila monster is a rare, poisonous lizard with a nasty bite, but at least one doctor believes its venom is part of a medical breakthrough.

Years ago, researchers found a hormone in the Gila monster's saliva that helps diabetics better control their blood sugar; that drug, now created synthetically and marketed as Byetta, has been on the market for three years and is sometimes referred to as "lizard spit" or "monster spit."

"It's a very effective medication," said Dr. Antonia Verso from Banner Health.

Verso said Byetta is not only helping her patients control diabetes -- it has also helped them lose weight.

"In my patients, the average (weight loss) is about 18 pounds," she said.

Ralph Bustamante, a patient of Verso, lost nearly 40 pounds while on Byetta. Other diabetes drugs caused him to gain weight, he said.

"My experience has been phenomenal," Bustamante said. "The drug has helped me reduce my numbers, to take me from being an out-of-control diabetic to one that's in control."

The drug, however, is not without risks. The FDA is working with the drug's manufacturer to strengthen warnings about potential pancreas problems patients can experience while on Byetta.

Nevertheless, Verso said, the benefits outweigh the risks. She is part of a new study that hopes to analyze the effects of Byetta on health and weight, she said.

The study will start this month.