Bats’ sky-high blood sugar levels offer new hope for diabetes research: Study

“Since they have dietary specialization that encompasses all the diet types across mammals, we can, for the first time, study the mechanisms of metabolic evolution in response to diet,” Jasmin Camacho, a postdoctoral research associate at Stowers Institute for Medical Research and co-first author of the study, told Interesting Engineering (IE).

“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 Camacho. “We are seeing a new trait we didn’t know was possible.”

Studying bats for understanding glucose metabolism

Thirty million years ago, the Neotropical leaf-nosed bat fed exclusively on insects. Over time, these bats evolved into a diverse range of species, each adapting to a different diet. Today, various lineages of these bats have specialized diets, including fruits, nectar, meat, and even blood.

“Bats have an extraordinary range of dietary specializations, including nectar, fruit, insects, meat, fish, and even blood. This dietary diversity allows researchers to study various metabolic adaptations within a single taxonomic group, offering insights into how different diets influence metabolism. No other group of mammals show this type of dietary diversity,” Camacho told IE.

In addition to their dietary adaptations, bats face significant physical demands from flight, which places immense stress on their bodies. Despite this, bats have evolved to maintain strong immune systems and metabolic health, allowing them to thrive despite the high levels of oxidative stress generated by their metabolism.

Camacho says, “Since flight also puts a lot of stress on the body, bats maintain robust immune systems and metabolic health despite being exposed to high levels of oxidative stress from their metabolism. Their ability to balance immune function and metabolic processes makes them an excellent model for studying the interplay between metabolism and immune health.”

“What is even more interesting, is despite their high metabolic rates, many bat species have exceptionally long lifespans for their size. This paradox provides a model to explore the relationship between metabolism, aging, and longevity, challenging conventional views that higher metabolic rates lead to shorter lifespans,” she explains.

The gut’s role in moderating blood sugar levels

To explore how bats diversified their diets, researchers embarked on extensive fieldwork in the jungles of Central America, South America, and the Caribbean over several years. These catch-and-release expeditions involved performing glucose tolerance tests on nearly 200 wild-caught bats from 29 different species. After feeding the bats one of three types of sugars—each corresponding to diets of insects, fruits, or nectar—the researchers measured the concentration of sugar in the bats’ blood.

The study revealed a spectrum of adaptations to maintaining healthy glucose levels among different species of leaf-nosed bats. These adaptations include changes in intestinal anatomy and genetic modifications affecting the proteins that transport sugar from the blood to the cells.

“We have uncovered key insights into the gut’s role in regulating blood glucose levels, a critical factor in the risk of developing diabetes. The adaptations observed in bats lead to blood glucose levels exceeding 750 mg/dL—the highest recorded among mammals.”

“These findings underscore the duodenum [a part of the small intestine] as a crucial regulator of blood glucose and a promising target for future treatments aimed at reducing sugar absorption after meals to improve glycemic control in the fight against the human diabetes epidemic,” Camacho told IE.

The study has been published in Nature Ecology & Evolution.