Researchers trying to find a cure for diabetes said Thursday they had discovered a new hormone, previously unknown to medicine, that makes the very cells destroyed by the disease. It has the potential to transform the way we now care for diabetes – the No. 7 killer in the United States, the researchers said.

The new hormone, which they have named betatrophin, encourages the growth of beta cells in the pancreas. These beta cells produce insulin, which people with diabetes lack. Without insulin, sugar can build up in the blood, damaging organs and blood vessels and causing blindness, kidney failure and the loss of limbs.

So far the team at the Harvard Stem Cell Institute have only worked in mice. But they say humans make betatrophin, too, and it’s almost identical to the mouse type.

“It is very exciting to think this could turn into a treatment for people,” Dr. Douglas Melton, who led the work, told NBC News.

“We discovered that only one gene was responsible for making more of these insulin-producing beta cells. Once we were able to make the hormone as a protein, like insulin, then we would be able to administer it.”

Nearly 26 million Americans have diabetes, according to the Centers for Disease Control and Prevention. About 90 percent have type 2, which is linked to poor diet and a lack of enough exercise, although there’s a genetic component, too. Type 1 or juvenile diabetes is caused whenthe body’s immune system mistakenly attacks the pancreatic beta cells.

Both types can eventually leave patients without the ability to make insulin properly. In type 1 diabetes and some cases of type 2, patients must inject insulin when they eat to make sure the body metabolizes the food properly and doesn’t get too much or too little sugar.

It’s tricky and most people don’t get it just right. Many researchers are trying to find something better.

Melton’s lab has been focused on regenerating or replacing beta cells. His colleague Peng Yi stumbled on the new hormone and the team was astonished to find that an overlooked gene controlled production of a hormone that directly stimulates beta cell growth.

“It is rare to find a new hormone, especially one so specific,” Melton said. “I've never seen any treatment that causes such an enormous leap in beta cell replication.”

The discovery, reported in the journal Cell, is still in the very early stages, scientifically. A lot could go wrong. In a best-case scenario, Melton says, researchers will find a way to make the new hormone easily and make it into an injectable form.

“We would provide this hormone, the type 2 diabetic will make more of their own insulin-producing cells, and this will slow down, if not stop, the progression of their diabetes,” Melton says. “You might inject this hormone once a month or once a year to make more beta cells and they are going to make the insulin. If your own beta cells are making the insulin, they will act to regulate your metabolism much better than the intermittent injections diabetics do.”

Two companies -- German biotech firm Evotec and Janssen, the drug development arm of Johnson & Johnson, have licensed the discovery and are already working to try and make betatrophin into a human treatment. It’s not straightforward.

“We have been able to grow it in all kinds of cells, but we can’t get it out in soluble, usable form yet. That’s a little bit puzzling,” Melton says.

“Now, in the next year, we will make the hormone and see if we can cure type-2 diabetes in mice. We also want to see if we can forestall the onset of type-1 diabetes in mice.”

Dr. Julia Greenstein, vice president for cures at the Juvenile Diabetes Research Foundation or JDRF, says the research has the potential to change the course of diabetes treatment.

“We have known for a long time that normal beta cells proliferate and expand in a number of situations like pregnancy and obesity. We just haven’t understood the science enough to understand what proteins or hormones might be responsible for that,” said Greenstein, who was not involved in the research. The federal government, through the National Institutes of Health, paid for the Harvard team’s experiment.

Greenstein predicted that many different groups of scientists will begin to tackle the problem of making betatrophin work – or perhaps try to make a drug that would duplicate its effects. One important concern: causing cells to prolferate can lead to cancer.

Meanwhile, Melton’s not putting all of his eggs into that basket. His lab is working on a variety of ways to repair the pancreas and cure diabetes, including the use of human embryonic stem cells, which he’s working to transform into pancreatic cells.

His adult son and daughter have type-1 diabetes and he fears they wouldn’t benefit from something like betatrophin, because their pancreatic beta cells are so badly damaged already.

“They are unlikely to have enough beta cells on which this hormone can act. We need something else,” Melton says. “I am really keen to solve that problem. We are not giving up on that.”