Some bats can eat tons of sugar without any health problems. Are there lessons for diabetes? | WFAE 90.7

Updated: August 17, 2024, 7:11am

Some bats like candy.

Well, I don't like sweets you can buy at the sweet shop, I like fruits that are full of sugar.

“We call it nature's candy.” Way GordonA biologist at Menlo College, she was capturing neotropical bats in northern Belize this spring. Bat-a-thonThis is an annual event that brings together dozens of researchers to study many species of Neotropical bats, including fruit-eating flying foxes.

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Gordon believes these mysterious hairy, flying creatures may hold clues for treating diabetes in humans: When fruit bats gorge on fruit, blood sugar levels spike—but somehow, the bats are harmless.

“These bats control sugar like it's nothing.” Nadav AkhitovStanding beside Gordon is Ahitoff, director of the University of California, San Francisco's Institute of Human Genetics. Ahitoff likes to think of bats as little superheroes, each with their own special superpower — in the case of fruit bats, that superpower is the ability to process huge amounts of sugar.

This isn't the case for humans: We have to watch our sugar intake, because “a diet high in sugar leads to things like diabetes,” Gordon says. “And that's going to cause a lot of chaos.”

According to Gordon, fruit bats may have enough sugar circulating in their blood to give them energy to fly between fruit meals. “They're really dependent on having a constant supply of sugar in their blood for energy to survive,” Gordon says. But within 30 minutes of a fruit feast, bats can bring their blood sugar levels back down to nearly normal.

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“So the question is,” Gordon asks, “how do they [their blood sugar] “How can someone become so hypoglycemic so quickly? How can they manage this without developing metabolic disease?”

Fruit bats have different neural circuits

Much of the sugar we ingest is stored in our blood as glucose. Insulin helps manage glucose and deliver it to cells that need it. However, over the past 20 years, a combination of factors, including decreased physical activity and changes in diet, has led to a rapid increase in diabetes worldwide. The disease is characterized by an inability to control blood sugar levels and can lead to heart disease, nerve damage, blindness and even death.

To learn more about how fruit bats manage their sugar intake, Gordon decided to compare them to bats that eat insects, which are high in protein but low in sugar.

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She, like Ahitov and his colleagues, was particularly interested in the kidneys and pancreas, organs that researchers already knew looked different to the naked eye in the two bat species.

So Gordon zoomed in to compare the cells and genes of those organs, “and what was really exciting was that in the fruit bats we saw a lot more cells responsible for maintaining blood sugar levels,” she says. That means that compared with the insectivorous bats, the fruit bats had more pancreatic cells capable of producing insulin.

What's more, fruit bats appear to have genetic differences that allowed them to quickly control the amount of glucose in their bloodstream: “Their genes were primed to secrete insulin, for example, as soon as it was needed,” Gordon says.

The results were published in the journal Neurology earlier this year. Nature CommunicationsGordon says that these characteristics of flying foxes may one day teach us how to help. people Regulate Their Blood sugar level.

“Yes, we're still a long way off,” Gordon said, “but it will be the ultimate 'Wow, we did it.'”

Olympians with ambiguous sugar consumption

When it comes to bats, there are superheroes… and then there are superheroes.

take Glossofaga mutica This is a species of bat that lives in the Americas and feeds on the nectar of flowers that are the color of milk chocolate.

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“These are basically nocturnal hummingbirds that drink nectar from flowers.” Jasmine Camacho“Over time, animals have evolved to roaming around and enjoying sweet things,” says Jonathan Myers, an evolutionary biologist at the Stowers Institute for Medical Research in Missouri.

Camacho is in Belize taking part in the Batathon and is standing in a walk-in tent with a large screen at 2 a.m. one night. Glossofaga mutica This is a bat caught in the early evening. If you give the bat a little bit of sugar water, it will lick it up right away. It's just a drop for the bat. Nectar-eating bats consume even more sugar than fruit-eating bats.

“Their lifestyle is extreme,” she says. “They can forage for up to 800 flowers a night, which means they're essentially eating their body weight in sugar every night. Imagine eating your body weight in sugar every day.”

In humans, it would be a one-way ticket to diabetes, obesity or worse metabolic disorders.

“This is industrial-grade,” Camacho says. “This is toxic. It's lethal.” But fruit bats are “beyond the limits of what we know any other kind of mammal can survive,” she says, and somehow they don't get sick. Unlike fruit bats, which “can bring their blood sugar down quickly with insulin,” she says, “they keep their blood sugar higher for a longer period of time.”

Camacho wants to know how nectar-eating animals can get so much glucose without any health problems. The answer lies, at least in part, in flying Bats do. Imagine a nectar-feeding bat flapping its wings at least 12 times per second, flying from flower to flower, sipping on glucose and other sugars all night long. That's a lot of aerobic exercise.

“When you exercise, you get about 100 times more glucose than you can get insulin from,” Camacho says. So, “when you exercise, you burn more energy.”

So the bats might not be soaking up all the sugar and storing it in their bodies. Instead, like fruit bats, they're circulating it in their bloodstream to use as an energy source to fly to the next flower. That way, “energy is always available,” says Camacho's colleague Valentina Peña, who will start a PhD in ecology and evolutionary biology at the University of California, Irvine this fall.

Humans are similar to bats: Exercise also affects how we process sugar, which is why Camacho is intrigued to see the connection between flight and bats' ability to metabolize large amounts of sugar.

In particular, they want to know what molecules bats use to regulate and lower their blood sugar levels during exercise, and how they protect their bodies from the accumulation of cell and DNA damage that typically comes from digesting large amounts of sugar.

“Maybe that can tell us some things about how we can live healthier,” Camacho explains, including, perhaps, how to treat or prevent the onset of obesity and type 2 diabetes. “There's a lot we can learn from how they came to thrive on a sugary diet.”

Super fun puzzles

Camacho lets the bats he's just fed rest for a few minutes while they fly around the tent, hoping to sample their blood for molecular clues about how they process the sugars they need to fly.

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The bats have about 10 minutes to fly, but after about a minute they land on the side of the tent. “Not all bats are going to cooperate,” she said.

Camacho and Peña also tested another bat of the same species, and unlike its colleague, this one soared high into the air and continued to fly for up to 15 minutes.

Camacho is delighted. “Oh, what a beautiful bat,” she says in a sweet voice. “I love it!”

After capturing the bat in a net again, Camacho and Peña took a blood sample. Peña will freeze some of the samples to study in a lab later, but he also applied a glucose meter, like the ones diabetics use to check their blood sugar levels, to a drop of the bat's bright red blood.

Camacho was astonished. “Oh my God!” she cried. “I can't believe it.”

She thought her blood sugar was low. Similar experiments in the lab The bats' blood levels are much higher than in studies done by other researchers. But even after 15 minutes of flying in a more natural environment, the blood levels are still so high that no change can be measured. The bats' blood level meters are at their limit, so the display only reads “high.” If such levels continued for a long time without medical intervention, a human would die.

“It doesn't make sense,” she says with a mixture of disbelief and amazement. “Why don't they die?”

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