Some bats thrive with blood sugar levels that would kill humans

Some bats have the highest blood sugar levels ever observed in any mammal, surviving and even thriving with levels that would kill a human, researchers report.

These bats could provide insights into treating and managing diabetes , they added.

"Our study reports blood sugar levels that are the highest we have ever seen in nature -- what would be lethal, coma-inducing levels for mammals, but not for bats," said co-lead investigator Jasmin Camacho , a postdoctoral research associate with the Stowers Institute for Medical Research in Kansas City, Mo. "We are seeing a new trait we didn't know was possible."

For the study, published Wednesday in the journal Nature Ecology & Evolution , researchers performed blood sugar tests on nearly 200 wild-caught bats across 29 species, after feeding them sugars associated with a diet of either insects, fruits or nectar.

"We saw various ways sugar is assimilated -- absorbed, stored and used in the body -- and how this process has become specialized due to different diets," said co-lead investigator Andrea Bernal-Rivera , a former researcher with the Stowers Institute.

These results indicate that bats have evolved strategies to survive based on the diet they are presented in their environment, researchers said.

Thirty million years ago, the Neotropical leaf-nosed bat survived solely on insects. Those bats have since evolved into many different species of bat by changing what they eat, researchers said.

Different species of leaf-nosed bats have developed different adaptations to help them control their blood sugar based on diets ranging from fruits, nectar, meat and even blood, results show.

"Fruit bats have honed their insulin-signaling pathway to lower blood sugar," Camacho said in an institute news release. "On the other extreme, nectar bats can tolerate high blood glucose levels, similar to what is observed in people with unregulated diabetes. They have evolved a different mechanism, and it does not seem to depend on insulin."

Bats with sugar-rich diets appear to have evolved longer intestines, as well as intestinal cells with greater surface area, researchers said. This allows them to better absorb nutrients from food.

In addition, nectar bats have a gene responsible for blood sugar transport that is always activated, a trait also observed in hummingbirds, researchers said.

The new study "provides not only metabolic characteristics of various bat species with different diets, but also their intestinal morphology, and candidate genomic regions and protein structural differences that could be driving dietary adaptations," said researcher Nadav Ahituv , a bioengineering and genetics professor with the University of California, San Francisco.

All of this might have implications for the health of people battling diabetes and other illnesses.

The new data "could progress the development of novel therapeutics for a variety of metabolic diseases in humans," Ahituv said.

More information

The American Diabetes Association has more about diabetes .

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