Gila Monster and GLP!

Gila monster is the only venomous lizard native to the United States and one of only two known species of venomous lizards in North America

Venom is produced in modified salivary glands in the Gila monster's lower jaw, unlike snakes, whose venom is produced in the upper jaw. 
In 2005,  drug exenatide was approved (marketed as Byetta) for the management of type 2 diabetes. It is a synthetic version of a protein, exendin-4, derived from the Gila monster's saliva.
Exenatide led to healthy sustained glucose levels and progressive weight loss. The effectiveness is due to the fact that exenatide is about 50 percent identical to glucagon-like peptide-1 analog (GLP-1), a hormone released from the human digestive tract that helps to regulate insulin and glucagon. The lizard protein remains effective much longer than the human hormone, helping diabetics keep their blood sugar levels under control. 
Exenatide slows the emptying of the stomach and causes a decrease in appetite, contributing to weight loss.
The saliva of the Gila monster contains many chemicals which can be deadly. One of these has been shown to affect memory. Several companies have been researching the abilities of this chemical to help memory loss due to various diseases such as Alzheimer’s, schizophrenia, and ADHD. Gilatide, derived from exendin-4, has been shown to dramatically heighten memory in a study with mice. Gilatide is likely to be researched further to provide help to Alzheimer’s patients.

Source: Wikipedia