For people with type 2 diabetes, could the days of having to jab themselves with a needle whenever they need insulin be over?
It's now a distinct possibility, say researchers who have developed a capsule that can deliver insulin once it reaches the stomach. The new device has only been tested in animals so far, and such findings don't always pan out in humans, but the scientists say the results look promising.
"If you try to deliver insulin orally, the acid and enzymes [in the digestive system] break up the proteins," explained senior study author Dr Giovanni Traverso. He's from Brigham and Women's Hospital in Boston and the department of mechanical engineering at MIT in Cambridge, Mass.
That's why insulin - a hormone that helps regulate blood sugar - has to be delivered by injection. But Traverso said that people with type 2 diabetes often delay beginning treatment with insulin because of the discomfort and stigma attached to insulin injections.
"People would prefer the oral route over injections," he said.
To try to meet this challenge, the researchers developed a capsule that contains a small needle that's made of compressed insulin. The capsule is about the size of a blueberry.
When the device reaches the stomach, the capsule reorients itself and injects the insulin into the lining of the stomach.
Lead author Alex Abramson, a Ph.D. student in the department of chemical engineering at MIT, said, "The system had to be self-orienting. The stomach is a large space and there's no guarantee where it will land."
So, the researchers borrowed "technology" from the leopard tortoise, found in Africa. The animal's shell has a high, steep dome. This allows it to right itself if it rolls onto its back.
The researchers also had to make sure the capsule had a chance to right itself before the injection occurred. To accomplish this, they loaded the insulin needle onto a compressed spring that's held in place by a sugar disk. The sugar disk takes 5.5 minutes to dissolve, according to Abramson.
Once it dissolves, the insulin needle is injected into the stomach lining. There are no pain receptors in the stomach, so the injection shouldn't hurt, the researchers noted.
After the capsule has delivered its contents, the remains pass harmlessly through the digestive system.
Tests in pigs have shown the device is able to successfully deliver insulin in the same quantities that people with type 2 diabetes would typically take.
The researchers also looked at the stomach tissue where the insulin was injected and saw no signs of damage or abnormalities. They also didn't see any changes in the way the pigs ate or in their stool patterns.
Traverso said the researchers will continue the animal experiments and are hoping to test the insulin capsule in humans in approximately three years. In addition to insulin, he said that the capsule system could likely be used to deliver drugs for other diseases.
Endocrinologist Dr Minisha Sood is from Lenox Hill Hospital in New York City, and was not part of the study. "This technology is something I never imagined would be possible. Thus far, it's only been tested in animals, but it's a proof-of-concept study that is promising, and I'm looking forward to seeing how this pans out in human trials," she said.
"Making oral insulin available will dramatically improve the options for people with diabetes - it would be life-changing," Sood explained. Currently, she added, people with diabetes who need to be on insulin often have a delay of seven to 10 years before they begin insulin therapy. Having to inject insulin is one of the main reasons for this delay, she said.
The capsule system was developed by a team of researchers from MIT, Brigham and Women's Hospital, and insulin manufacturer Novo Nordisk.
The study was published February 7 in the journal Science,