In 1992, Dr John Eng discovered a molecule in Gila monster venom; decades later, his finding helped pave the way for widely used type 2 diabetes medicines

Meet John Eng: The hospital doctor whose Gila monster discovery helped open the door to Ozempic. (Photo: X post)

Long before Ozempic became one of the world’s most talked-about medicines, a doctor working at a Veterans Affairs hospital in the Bronx was studying something far less glamorous: the venom of a desert lizard.His name was Dr John Eng. In 1992, his research helped identify exendin-4, a molecule found in the venom of the Gila monster. That discovery eventually led to exenatide, sold as Byetta, the first GLP-1 receptor agonist approved for treating type 2 diabetes. The science behind that breakthrough would later help establish a drug pathway that transformed diabetes and obesity treatment.

The question hidden inside a lizard

The Gila monster, a venomous lizard found in the southwestern United States and northwestern Mexico, became an unlikely subject of medical research.Scientists had been studying GLP-1, a hormone produced in the human body that helps stimulate insulin release when blood glucose levels rise. But there was a major problem: natural GLP-1 breaks down very quickly, limiting its usefulness as a medicine.Eng and his collaborators isolated exendin-4 from Gila monster venom. The molecule acted on the same GLP-1 receptor but remained active far longer than natural GLP-1, making it a promising candidate for drug development.

A discovery that almost went nowhere

Eng worked at the James J. Peters VA Medical Center in the Bronx, where he treated patients while pursuing research into peptide hormones.After identifying exendin-4, the discovery faced a difficult journey towards becoming a medicine. Eng eventually licensed the technology to Amylin Pharmaceuticals, which developed a synthetic version of exendin-4 called exenatide.In 2005, the US Food and Drug Administration approved exenatide as a treatment for type 2 diabetes. Marketed as Byetta, it became the first approved GLP-1 receptor agonist and demonstrated that this biological pathway could be successfully turned into a medicine.

So, did John Eng discover Ozempic?

Not exactly.Ozempic contains semaglutide, a different GLP-1-based medicine developed by modifying the human GLP-1 hormone to make it last longer in the body. It is not made from Gila monster venom.But Eng’s discovery of exendin-4 and the success of exenatide were important milestones in demonstrating the medical potential of targeting the GLP-1 receptor. That broader scientific journey eventually contributed to the development of newer GLP-1 medicines, including semaglutide.

From an unusual experiment to a medical revolution

The story of John Eng is a reminder that major scientific breakthroughs do not always begin in famous laboratories or with obvious ideas.A molecule found in a venomous lizard helped researchers overcome one of the biggest challenges associated with GLP-1: finding a version that could remain active long enough to become a practical medicine.Today, GLP-1 medicines are changing the treatment of diabetes and obesity. But one important chapter of that story began decades earlier, when researchers looked at a slow-moving desert lizard and discovered that nature had already created a molecule scientists had been searching for.Disclaimer: This article is based on publicly available research, scientific literature and reports about Dr John Eng and the development of GLP-1-based medicines. TOI Education does not independently verify all historical accounts or research interpretations mentioned in the source material.