Is Type 2 Operable?
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.
As noted previously, this theory has not been proved. It is not a cure that you'll see becoming common soon. But the theory is fascinating and makes sense to me.
The body has many many similar control systems, in which one hormone or nerve connection, sometimes both, stimulates something and another one inhibits it, like a building with a furnace and an air conditioner, or a car with an accelerator and brakes. The goal is to keep some physiological value within a narrow range. We think of this as maintaining good balance. Scientists call it homeostasis.
The most obvious example is insulin and glucagon. Insulin makes BGs go down and glucagon makes them go up. When everything is working well, high BGs stimulate the secretion of just enough insulin and low BGs stimulate the secretion of just enough glucagon.
Another example is body temperature. When your temperature gets too high, nerves tell the blood vessels in your skin to dilate, to help disperse the heat, and your skin gets pink. When your temperature gets too low, other nervous impulses tell your cutaneous blood vessels to contract, to avoid giving off heat, and you get pale.
When your blood pressure gets too high, a combination of hormones tells the blood vessels to dilate, and this reduces the pressure. When the blood pressure gets too low, the hormones tell the blood vessels to contract, and this raises blood pressure.
One of the substances that tell blood vessels to contract is called angiotensin II, and the ACE inhibitors reduce the amount of angiotensin II, which keeps the vessels from contracting as much and reduces the blood pressure.
There are many examples of this type of control mechanism. Our bodies are in a constant delicate balance maintained by myriad substances, and all it takes is a flaw in one part of the system, and everything can get out of whack (note complex scientific term "out of whack").
So it could very well be that Rubino's hypothesis is correct. Even if it's not, it will undoubtedly stimulate research in this area. If we could fix type 2 diabetes in the early stages by surgery, the cost savings would be immense. And with more research, the exact surgery that was needed would be worked out and would probably be less invasive, with fewer long-term complications, than the complex gastric bypass operations being performed today.
However, even in the future, surgery probably won't be a real cure. Not everyone getting gastric bypass surgery, for example, sees their type 2 diabetes reverse. The results are best in those who have the operation when they're still in the early stages. The operation has no effect on type 1 patients.
And even Rubino doesn't refer to a "cure" but rather says that the patients are "in remission."
A cure is coming, but probably not tomorrow. In the meantime, we should focus on the treatments we have today: diet, exercise, judicious use of drugs, including insulin, to keep our BG levels under control, and attention to the other aspects of our health including blood pressure and lipid levels.
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