Grizzly bear hibernation may provide valuable clues to how obese humans handle sugar and develop diabetes. New research published in the journal Cell Metabolism uncovers the way bears’ cells are able to control their bodies’ response to insulin when they become obese during hibernation in the fall.
The findings reveal the ongoing complexity in the obesity and diabetes link in humans. Researchers found when grizzly bears hibernate they store all of the fuel they’ll need for hibernation into their fat tissue, while other animals and obese humans store their fat in liver and muscle. In type 2 diabetes, which is one of the most common consequences of obesity, cells lose the ability to respond to insulin that’s necessary for sugar regulation.
"This is in contrast to the common notion that obesity leads to diabetes in humans," the study’s lead researcher Dr. Kevin Corbit, from the drug maker Amgen Inc., said in a press release. "Our results clearly and convincingly add to an emerging paradigm where diabetes and obesity — in contrast to the prevailing notion that the two always go hand-in-hand — may exist naturally on opposite ends of the metabolic spectrum."
When investigators found obese grizzly bears’ sugar levels weren’t changing even though they had a significant amount of sugar in their system for hibernation, they were surprised and it led them to wonder what would happen if our bodies reacted the same way to obese conditions. The protein PTEN within the bears’ fat cells turns off during hibernation, so they develop diabetes while they’re asleep but then are cured once they awaken in the spring time.
Corbit and his team believe if they can control and lower the PTEN mechanisms in obese people, they may also be able to protect them from diabetes. Humans with lower levels of PTEN would have bear-like biological levels and would be insulin sensitive even though they’re obese. If we could control the mechanism, the relationship between obesity and type 2 diabetes may decrease and no longer would excessive weight gain cause health issues that cause a person to play a balancing act with their sugar levels.
"While care must be taken in extrapolating preclinical findings to the care of particular patients,” Corbit said. “We believe that these and other data do support a more comprehensive and perhaps holistic approach to caring for patients with diabetes and/or obesity."
There are 29.1 million Americans living with diabetes and another 8.1 million undiagnosed cases, according to the American Diabetes Association. Within the U.S. population, there are 78.6 million obese adults. Obesity-related conditions include not only type 2 diabetes, but also certain types of cancers, heart disease, and stroke, according to the Centers for Disease Control and Prevention.
"Moving forward, this more sophisticated understanding of the relationship between diabetes and obesity should enable researchers not only to develop therapies targeting these mechanisms, but also to identify the appropriate patients to whom these therapies should be targeted,” Corbit said.
Source: Corbit KC, Nelson L, Jansen HT, Galbreath E, Morgenstern K, Gehring JL, et al. Grizzly Bears Exhibit Augmented Insulin Sensitivity while Obese Prior to a Reversible Insulin Resistance during Hibernation. Cell Metabolism. 2014.