Lizard Saliva Reduces Sugar Overload and Regulates Digestion

the black and tan bumpy head of a gila monster

Biological Strategy

Gila monster

Sam Stier & AskNature Team

Image: Andrew DuBois / Flickr / CC BY NC - Creative Commons Attribution + Noncommercial

Regulate Cellular Processes

Cells are the basic building blocks of all living systems, so cellular processes dictate how physiological processes occur within those systems. Cells (whether entire unicellular organisms or parts of multicellular living systems) grow, metabolize nutrients (that is, chemically transform them), produce proteins and enzymes, replicate, and move. Cells as part of multicellular systems rarely act alone, instead having ways to signal to start and complete simple to quite complex interactions. How skin heals is a good example of the role of cellular processes. Blood cells called platelets release clotting factors to stop the bleeding; white blood cells rid the area of foreign materials and release molecules to coordinate healing; cells called fibroblasts start rebuilding using proteins called collagen; new blood vessels form; and skin cells called keratinocytes create the new surface.

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Maintain Homeostasis

When a living system is in homeostasis, it means that internal conditions are stable and relatively constant. For example, a human’s internal temperature is approximately 37 degrees Celsius (98.6 degrees Fahrenheit) unless there’s an illness. The human body maintains this temperature despite external ambient temperature. However, as with all physiological processes, maintaining homeostasis requires communication and coordination. So living systems have ways to detect changes from the norm, mechanisms to cause an adjustment, and negative feedback connections between the two. A desert lizard called the Gila monster offers a good example of maintaining homeostasis. The lizard goes from eating large meals to fasting for extended time periods. To maintain its blood sugar levels at a steady level, when food is scarce, its endocrine system releases a hormone that raises its blood sugar levels.

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Reptiles

Class Reptilia (“creeping”): Lizards, crocodiles, turtles, snakes

Reptiles retain some of the key characteristics that first enabled vertebrates to live permanently on land. They have dry skin covered in scales made of keratin that help prevent water loss. (Amphibians still need to stick close to water to keep their skin moist.) Many reptiles reproduce by laying eggs that are watertight and have a yolk, so eggs can develop on land while staying moist and nourished. Reptiles are also ectotherms, meaning they don’t produce their own body heat. This means they burn through energy much more slowly than “warm blooded” creatures of the same size. It also means that they need to keep warm to keep active, which is why you might see them spending a seemingly inordinate amount of time simply basking in the sun.

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The Gila monster’s venomous saliva contains a molecule called exendin-4 that extends insulin production by mimicking a natural hormone, enabling efficient sugar processing after large meals.

Introduction

Gila monsters (Heloderma suspectum) are one of the few venomous lizards in the world, inhabiting the deserts of the southwestern United States and northern Mexico. Life in these arid environments is feast or famine. When food is available, these lizards gorge themselves—sometimes consuming up to half their body weight in a single meal.

To survive long periods between meals, they must make the most of the energy they get. This means carefully regulating how sugar enters their cells and is stored or used. Their ability to do this efficiently, using a compound in their saliva, is a life-sustaining —and an inspiration for treating diabetes in humans.

The Strategy

Like all vertebrates, Gila monsters convert carbohydrates into —a sugar used by cells for energy. Normally, after a meal, the body produces to help move glucose from the blood into cells. A secondary , called GLP-1 (glucagon-like peptide-1), boosts insulin production. However, in most animals, GLP-1 breaks down quickly and only offers a brief signal.

But in the Gila monster’s saliva, there’s a version of this hormone called exendin-4. It’s remarkably stable and sticks around much longer in the bloodstream. This allows the to continue releasing insulin over extended periods—hours rather than minutes. This is especially helpful after a large meal, helping the lizard avoid sugar spikes and steadily draw energy from its food over time.

Exendin-4 functions similarly to GLP-1 by activating the same cellular receptors. However, its structure protects it from the enzymes that usually break down GLP-1. As a result, it provides longer-lasting effects with no need for constant replenishment. This adaptation ensures the Gila monster can stretch the energetic benefits of a rare meal for as long as possible.

"[E]xendin-4 was discovered in 1992 in the gila monster, after a researcher noticed the gila’s venom caused the pancreas of bitten victims to swell."

The Potential

This strategy has already changed human lives. In 1992, scientists discovered exendin-4 and began developing synthetic versions for human use. Today, this molecule is the basis for several medications used to treat type 2 diabetes, including exenatide (Byetta). These drugs help diabetics produce more insulin for longer periods without triggering blood sugar crashes. They also encourage weight loss by slowing digestion and increasing satiety after meals.

By studying the biochemistry of a desert-dwelling lizard, researchers have unlocked a sustainable, nature-inspired way to regulate blood sugar—without needing constant drug delivery. This is at its best: solving a human challenge by emulating a strategy refined through evolution.

Related Innovation

Innovation: Industry

Injectable Medication for Diabetics Inspired by the Gila Monster

AstraZeneca

Byetta from AstraZeneca is an insulin sensitizer that mimics proteins from Gila monster saliva to help Type 2 diabetics maintain glucose levels.

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Last Updated August 15, 2025

References

Journal article

Isolation and characterization of exendin-4, and exendin-3 analogue, from Heloderma suspectum venom: further evidence for an exendin receptor on dispersed acini from guinea pig pancreas.

J Biol Chem. 1992 Apr 15;267(11):7402-5. | J Eng, W A Kleinman, L Singh, G Singh and J P Raufman

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