Just chewing the fat (Image: Ingo Arndt/Minden Pictures)

Some bears can have their cake and eat it too. Grizzly bears become “diabetic” during hibernation, and then recover when they awake.

Lynne Nelson at Washington State University in Pullman and her colleagues investigated insulin activity in tissue samples taken from six captive grizzly bears over the course of a year.

As the bears put on weight in preparation for the winter, they responded normally to insulin – which prevents the breakdown of fatty tissue. But during hibernation, insulin effectively stopped working. That is a symptom in people with type 2 diabetes, in which high fat levels in the blood induce insulin resistance.


This insulin resistance allows the bears to break down their fat stores throughout hibernation, when they will not eat, drink or defecate for up to seven months. They survive on their fat before waking up, and begin to respond normally to insulin when they start to feed again.

Linked syndromes

“Diabetes and obesity may exist naturally on opposite ends of the metabolic spectrum,” says co-author Kevin Corbit of biotechnology firm Amgen in Thousand Oaks, California. “The cellular mechanisms that could be protecting people from diabetes, and the mechanisms leading to diabetes in other patients, may also be what protects them from becoming obese.”

The results suggest there is a chemical pathway involved in altering sensitivity to insulin. This pathway could hold the key for developing treatments for type 2 diabetes.

“Why do humans respond differently when they put on weight to these bears?” asks Gwyn Gould at the University of Glasgow, UK. “If we can identify that, we could produce therapies for diabetes.”

Journal reference: Cell Metabolism, DOI: 10.1016/j.cmet.2014.07.008