News media sound bites were ricocheting around the Internet last week suggesting that perhaps type 2 diabetes is an intestinal disorder that can be cured by surgery.
As Dr. Bill Quick pointed out in a recent blog, most of the popular accounts of the disease were overblown; Dr. Quick calls them "another piece of public relations flackery." Like so many reports of new medical advances, these reports in the news media were mostly based on a press release from the hospital where the research was done, a PR move designed to bring prestige to their hospital.
Despite all the media buzz, doctors aren't going to rush everyone with type 2 diabetes off to the operating room in the near future. The surgery that does seem to improve diabetes control in type 2 patients is major surgery, with attendant risks. It can also cause malabsorption of various nutrients, limited capacity for food intake for the rest of your life, and other unpleasant side effects. For that reason, it is currently limited to those who are very obese and for whom nothing else has worked.
However, the article in Diabetes Care describing the research proposed a fascinating new hypothesis of what causes type 2 diabetes.
The author, Francesco Rubino, suggests that type 2 diabetes is caused by an excess of some substance that inhibits the incretin hormones. The incretin hormones are produced in the gut after you eat and help to stimulate the beta cells to produce insulin. They also help to inhibit the production of the hormone glucagon, which does the opposite. The drug Byetta is supposed to mimic the action of the incretin GLP-1.
Rubino suggests that the body has a counterregulatory substance that is designed to keep the incretins in check, so you don't produce too much insulin after eating carbohydrate. It keeps you from going too low. He suggests that some people may produce too much of this "anti-incretin," and this keeps the incretins from doing their job.
So far, no one has discovered a substance that would play this role, but of course that doesn't mean it doesn't exist. Perhaps if people start looking for it, they'll find it.
Surgery that removes the upper part of the small intestine, called the duodenum and jejunum, from the pathway between the stomach and the lower intestine seems to improve blood glucose (BG) control. Rubino suggests that the overproduction of the counterregulatory substance occurs in the duodenum and jejunum when they are stimulated by food, and rerouting that part of the intestine will fix the problem.
People who undergo certain types of gastric bypass operations, the ones that reroute the duodenum, usually show great improvements in BG control within days or a few weeks, long before they've lost significant amounts of weight. Interestingly, rerouting the duodenum and jejunum of nondiabetics has no effect on BG control. Rubino says this is because they're not producing too much of the counterregulatory hormone to begin with.
