Scientists have discovered why a gastric bypass can help cure type 2 diabetes, according to a study published in the journal Science.
Researchers from Boston Children's Hospital reveal that the small intestine, which they had thought to be a passive organ, is actually a major contributor to the body's metabolism.
The researchers say that previous research has already shown that gastric bypass surgery can help resolve type 2 diabetes. However, they add that until now, the reason for this has been unclear.
The research team studied the after-effects of gastric bypass surgery in rats over a year and analyzed the way the small intestine processed glucose.
The researchers found that the small intestine uses and disposes of glucose. This regulates blood glucose levels which then helps to resolve type 2 diabetes.
Nicholas Stylopoulos of the division of endocrinology at the hospital, says:
"We have seen type 2 diabetes resolve in humans after gastric bypass, but have never known why. People have been focusing on hormones, fat and muscle, but we have shown in this study that the answer lies somewhere in the small intestine most of the time."
Gastric bypass surgery is a weight-loss treatment usually reserved for severely obese individuals. It works by redirecting the food into a smaller pouch in the stomach, bypassing the stomach and duodenum - the first section of the small intestine.
The researchers discovered that following gastric bypass surgery, the small intestine "reprograms" itself to produce GLUT-1, which is not usually present before surgery.
GLUT-1 usually works as a "transporter," responsible for removing glucose from the circulation and using it within the intestine.
However, the scientists discovered that after surgery, GLUT-1 takes glucose from the circulation and disposes of it, leading to stabilized glucose levels in the rest of the body.
The researchers say that of the rats analyzed after gastric bypass surgery, 100% had been cured of type 2 diabetes. They add that 64% of the diabetes had been cured by the gut surgery alone, while the other 36% could be a result of weight loss or other factors.
Nicholas Stylopoulos says this research could lead to investigating ways of "mimicking" the intestine's programming without the need for surgery: "Previously, we had not considered the intestine as a major glucose-utilizing organ. We have found this process is exactly what happens after surgery." Stylopoulos added:
With further research, we may find ways to bypass the bypass.
The results of our study are promising because, unlike the brain and other organs, intestines are easily accessible.
Furthermore, since cells in the intestine have such a short lifespan, we can easily study and pharmacologically manipulate them to use glucose, without long-term problems."
Previous research has suggested that although gastric bypass surgery helps diabetic symptoms disappear for some patients, it is not a long-term cure.
Scientists from the Group Health Research Institute carried out a study revealing that in 4,434 patients who had gastric bypass surgery, their symptoms of type 2 diabetes returned within five years of the operation.