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Unseasonal wake-up brought about by food

If bears are fed during hibernation, they wake up. But not completely.

A bear stands on his hind legs to grab an apple off a pole.
One of the WSU bears putting on weight in preparation for hibernation last year.

That’s the preliminary finding from a research study conducted this winter at the WSU Bear Research, Education, and Conservation Center, where scientists fed seven bears glucose every day for 10 days. Four WSU bears were not fed during hibernation, serving as the control group in the research.

One of the amazing abilities bears possess is that they are resistant to insulin during hibernation. That’s similar to Type 2 diabetes in humans. But bears can reverse that insulin resistance when they wake up in the spring.

“We found that blood glucose decreased when we fed them, suggesting that insulin sensitivity was restored,” said Heiko Jansen, associate professor in WSU’s College of Veterinary Medicine. “It wasn’t restored fully, it was about 50 percent of active season levels, but it did increase.”

Once the study ended, the bears returned to a normal hibernation state, suggesting bears can and would wake up if they have access to a food source.

“If a wild bear had access to high levels of carbohydrates, they may not need to hibernate,” Jansen said. “The feeding itself leads to physiological changes in bears.”

The study is ongoing, as Jansen and his team are still doing research on blood work and fat biopsies obtained during the study, as well as analyzing data from the samples they’ve already looked at.

“This is a big project, and it’s replicable each winter,” Jansen said. “So, we can potentially look at another nutrient, like protein for example, in the future.”