The reports sound nothing short of miraculous: people able to toss away their type 2 diabetes medications, sometimes just days after undergoing weight-loss surgery. The once obese become wondrously svelte. The successes of these new procedures—often called “bariatric surgery”—have even raised the tantalizing possibility that the operations could be a “cure” for type 2 (although never for type 1). And yet the medical community has not signed on in force, citing a lack of substantial scientific evidence and fearing that a rush to surgery could end up causing more problems than it is intended to solve.
Other questions remain: What is it about weight-loss surgery that causes the remission of type 2 diabetes in many cases? Who are good candidates for the procedures? Which type of surgery is most effective? And what are the long-term effects? Research is under way to get the answers, but definitive studies may take years. For now, people grappling with whether to undergo bariatric surgery should take a hard look at what is known about it—and what still isn’t.
The earliest reported surgery for weight loss was performed at the University of Minnesota in 1954. Since then, the procedures have been fine-tuned, some have been discarded (remember stomach stapling?), and new approaches are still being developed. For now, two types of bariatric surgery are predominant in the United States: gastric bypass and adjustable gastric banding, often called “lap-banding.”
Gastric bypass surgery is the weight-loss surgery most frequently performed in this country, typically what’s known as the “Roux-en-Y” version of the procedure. (It is named for César Roux, the Swiss surgeon who invented the method; the “Y” refers to the resulting configuration of the stomach and small intestine, which looks something like the letter “Y.”) Most gastric bypasses are done laparoscopically. In this approach, a surgeon uses a laparoscope, a snake-like camera, to see and work inside the body through just a small incision.
Bypass surgery has two major effects on the digestive system. It shrinks the size of the stomach by over 90 percent, from roughly the size of a fist to that of a thumb, reducing the amount of food a person can take in. The surgery also changes the path that food takes through the body. Normally, after leaving the stomach, food travels the 20-foot length of the small intestine. But after the surgery, food bypasses most of the stomach as well as about 4 feet of the small intestine, lowering the number of calories absorbed by the body. The rerouting of the food also hinders vitamin and mineral absorption, which is why bypass recipients need to take vitamins to stave off deficiencies. About 1 out of 5 patients will develop “dumping” syndrome, in which too much undigested food enters the small intestine, leading to diarrhea and abdominal cramps. This condition may be improved by eating smaller meals and fewer simple carbohydrates.
A second type of surgery, adjustable gastric banding, is quickly catching up to bypass in terms of popularity in the United States. This surgery is also performed laparoscopically in most cases, hence the nickname “lap-banding.” (Lap-Band is the trademarked name of a particular gastric banding device, one of two available models; the other is the Swiss Adjustable Gastric Band.) In banding, a fluid-filled belt is wrapped around the stomach. Tightening the belt forms two stomach pouches, a small upper pouch that receives food from the esophagus and a larger lower pouch that drains into the small intestine. The belt’s tightness can be adjusted by adding or subtracting saline solution through a port just under the surface of the skin that connects to the band via a thin tube. Cinching the band keeps a person feeling full, eating less, and losing weight. However, banding can lead to gastrointestinal distress, such as nausea or bloating.
A third type of surgery, not widely performed, is the duodenal switch. Compared with gastric bypass, duodenal switch results in a digestive path that uses more of the stomach and less of the small intestine. This combination appears to cause more weight loss and to allow patients to eat larger meals than bypass does. It also eliminates the side effect of dumping but creates a greater risk of malnutrition. A 2004 study found a 99 percent rate of diabetes remission with duodenal switch, but it is a complex surgery with a higher risk of death than bypass or banding (though that may be in part because it is not performed often).
Several other surgical methods are in experimental stages, including one that uses a tube through the mouth instead of an incision and others that rearrange the digestive tract in different ways to try to enhance the health benefits of surgery while reducing its side effects.
Next: Banding or Bypass?