The hormone was finally identified by analysing the DNA of two people with a rare disease called neonatal progeroid syndrome (NPS), which leaves them with unhealthily low levels of fat. Atul Chopra at the Baylor College of Medicine in Houston, Texas, and his team found that these people feel particularly lethargic because they lack a previously unknown hormone, which they have named asprosin.

“We looked into this super-rare condition, and the result was a discovery that could benefit millions with a much more common disorder – diabetes,” says Chopra.

Boost between meals

Experiments in mice showed that the hormone plays an important role in determining blood sugar levels, especially between meals. “Asprosin is released by fat cells and goes to the liver, telling it to immediately release glucose into the blood,” says Chopra. When blood glucose levels rise, production of the hormone is switched off.

Because the two people with NPS lack this mechanism for boosting the amount of glucose in their blood between meals, it causes them to feel lethargic. “I do get hungry very often,” says Abigail Solomon, one of the people who helped solve the puzzle. “I eat a lot, and frequently, mostly sugary stuff first, then protein.”

Diabetes researchers are intrigued by the finding. “The fact that asprosin hits the liver and causes overproduction of glucose, a key factor in type 2 diabetes, makes it even more interesting,” says Alan Cherrington of Vanderbilt University in Nashville, Tennessee.

Find it, block it

“My dream would be for patients on insulin to be able to reduce or even stop taking it,” says Chopra. “Maybe you could give them antibodies that block asprosin once a week to get blood glucose down, and this would mean patients having to take less insulin or get off it completely.”

Chopra’s team has already taken out a patent on the hormone, and is testing an asprosin-blocking antibody. “We’re treating diabetic mice, and it seems to be working well,” he says. They hope to begin a safety trial in humans within a couple of years.

Asprosin may also play a role in obesity and weight gain. While people with NPS, like Solomon, are extremely thin, Chopra’s team also found that obese people have twice as much asprosin in their blood than people who are not obese. “Obesity will be the focus of our next study,” he says. “It’s likely that as fat levels go up, asprosin goes up too,” he says.

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