Weight-Loss Surgery and Type 2 Diabetes
Is bariatric surgery a shortcut to a "cure"?
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.
Banding or Bypass?
Even the most common procedures have pluses and minuses. Unlike bypass, banding is reversible because it involves no restructuring of the digestive system. It's also a simpler surgical procedure, with shorter operation times and briefer hospital stays. The death rate within 90 days after banding is slightly lower than it is for bypass, but both are less than 0.5 percent, or about 1 in 200 patients, on par with such routine surgeries as laparoscopic gall bladder removal. Bariatric surgery is "one of the safest things that can be done with surgery," says Henry Buchwald, MD, PhD, a bariatric surgeon and professor at the University of Minnesota School of Medicine.
Bypass has advantages, too, particularly for people with type 2 diabetes. Weight loss is faster and greater with bypass. The average weight loss in the first two years after banding surgery is 60 pounds, compared with 100 pounds after bypass, though the difference narrows over time. Some patients show modest weight gain in the long term after both procedures. One study found that after 10 years, 9 percent of bypass patients and 25 percent of those who had banding ended up very near their original, pre-
surgery weight. But that may say more about the fact that lifestyle choices don't cease to matter on the operating table; how people eat and exercise is still key to successful weight maintenance.
Sometimes complications arise after bariatric surgery and recipients need a second operation; this is less common after bypass than with banding. For bypass, bowel obstruction is the most common trigger for additional surgery. With banding, the typical causes are band slippage or port problems like leakage.
Diabetes remission occurs more often and more quickly with bypass than with banding. (However, it's now clear that people with type 2 diabetes who either take insulin or have had the disease for at least 15 years, or both, are "significantly less likely to have remission" regardless of the procedure, according to David Cummings, MD, an associate professor and endocrinologist at the University of Washington in Seattle.) "When people get bands, their diabetes goes away in two to three years, clearly due to weight loss," says Walter Pories, MD, FACS, a bariatric surgeon and professor at the East Carolina University School of Medicine. "I don't think weight has much to do with it in gastric bypass." So, if a person eventually regains weight with banding, type 2 diabetes would be expected to return, but this is not necessarily the case with bypass.
How It Works
Gastric Bypass Surgery
This surgery dramatically reduces the size of the stomach by isolating part of it as a small pouch that receives food from the esophagus. The small intestine is cut at a point below the stomach and connected to the pouch. This creates a bypass for food around most of the stomach and part of the small intestine on its way to the large intestine, or bowel. The unused, upper part of the small intestine, which trails down from the bypassed stomach section, is looped around and connected farther down the small intestine (creating a "Y" shape), allowing gastric juices to drain.
Adjustable Gastric Banding
A fluid-filled belt is wrapped around the stomach, creating an upper pouch that receives food from the esophagus and a larger lower pouch that drains into the small intestine. A tube leads from the belt to a port just under the surface of the abdomen. Through the port, a doctor can either add or remove fluid from the belt to adjust its tightness. That determines how full someone feels by regulating how easily food can move between the stomach's upper and lower pouches.
In one sense, it's no surprise that a surgery resulting in weight loss might dramatically benefit people with type 2 diabetes. After all, there's a well-established connection between the disease and excess body weight. Still, the numbers are startling: In a 2009 analysis of more than 600 studies involving over 135,000 patients, 78 percent of patients with type 2 had complete resolution of their diabetes after surgery, and 87 percent had improved blood glucose levels. Other studies have come up with remarkably similar results. And as the twin global epidemics of obesity and type 2 diabetes continue to worsen, weight-loss surgery is becoming more common. In 2008, some 344,000 of these procedures were performed worldwide (including 220,000 in the United States and Canada), nearly 2 1/2 times the number done in 2003.
The rapid remission of type 2 diabetes after bypass—independent of weight loss—is the most enticing of discoveries about bariatric surgery. "All the operations that cause weight loss resolve [type 2] diabetes, but gastric bypass has a 'magic' quality in that it resolves diabetes before weight loss," says Buchwald. How does it work? The answer would seem to lie in anatomy. When food no longer traverses the upper part of the small intestine, cells in the lower small intestine see nutrients from food sooner and in greater quantities after a meal than they normally would. Some researchers believe this rearrangement may cause these cells to release more of an agent that lowers blood glucose. One candidate is GLP-1, a hormone made in the lower small intestine that helps with blood glucose control and weight loss; the diabetes medication exenatide (Byetta) works by behaving like GLP-1. Studies have shown that GLP-1 levels increase after surgery.
It's also possible that the benefits of bypass may be caused by suppressing some nasty agent that spurs the development of type 2 diabetes. Some suspect the culprit may be the hormone ghrelin, which raises blood glucose levels along with appetite, says the University of Washington's Cummings. He coauthored a 2002 study that found lower ghrelin levels in the body after bypass surgery. Or it may be some other hormone or molecule that science has yet to discover. "It's hard to imagine ghrelin is the whole story," says Cummings.
Another consequence of bypass surgery is that a big part of the digestive tract that used to come into contact with food no longer does. "It may be that the gut produces a toxic molecule … that hurts the cells," says Pories. Some researchers suspect that in people with type 2 diabetes something happens in this region when food is present to cause or worsen diabetes. After surgery, the theory goes, because food bypasses this area, that factor is removed and so is diabetes.
Solving the mystery of how bypass surgery triggers the remission of type 2 diabetes may do more than just satisfy scientific curiosity; it could provide the basis for a powerful new diabetes medication. "The hunt now is on for the molecular basis for this reversal [of type 2]," says Pories. "If we figure out what is the molecular factor, then we can develop a pharmaceutical." Call it surgery in a pill.
To Cut or Not to Cut
In the absence of such a breakthrough, the question at the heart of the debate is: Who stands to benefit the most from surgery, and who should stick with a more traditional treatment of diet, exercise, and medication?
The American Diabetes Association currently recommends considering bariatric surgery only for people with type 2 diabetes and a body mass index (BMI) of 35 and over. (Both a 5-foot, 4-inch person who weighs 204 pounds and a 6-foot, 258-pounder have a BMI of 35, for example.) But only 40 percent of people with type 2 are this overweight, which is why advocates of weight-loss surgery think it should also be considered at lower BMIs. Controversial research has suggested that even people with type 2 who aren't overweight may benefit from surgery. Some studies have shown that in normal-weight people, diabetes can be resolved using a type of surgery that captures the "magic" of bypass, but without the weight loss.
Complicating the debate further is the fact that the quality of data on bariatric surgery doesn't yet meet the highest standards. The kind of big, long-term studies of safety and efficacy that would be needed for approval of, say, a new medication haven't been done for weight-loss surgery. Plus, the different types of bariatric surgery seem to have their own risks and benefits.
There is general agreement that weight-loss surgery should be an option for severely obese people with diabetes. A 2007 article in the New England Journal of Medicine found that people with BMIs of 33 and above (the average BMI was around 45) who had undergone gastric bypass surgery had a 92 percent reduction in diabetes-related deaths and a 40 percent reduction in deaths from any cause compared with people with the same BMIs who didn't have surgery. But the study didn't consider the possibility that healthier, wealthier patients are more likely to have gastric bypass, which could have skewed the results.
For people under the age of 18, opinions are divided. Some studies support doing surgery for young people who are severely overweight, or at least show that it can be done safely. "I think children fit into the same equation [as adults]," says Buchwald. "The argument is twofold: What if you operate on a child and the child dies? Horrible. But if the child doesn't die, you've saved a life."
Even with adults, the issues aren't clear-cut. "As you move it into people with ordinary type 2 diabetes [who are not severely obese], is there a justification for doing major surgery? That's the gray zone now," says Harold Lebovitz, MD, a professor and endocrinologist at the State University of New York Downstate Medical Center. In 2009, a statement from the Diabetes Surgery Summit, in which experts developed guidelines for the use of bariatric surgery in diabetes, supported the use of gastric bypass for people with poorly controlled type 2 and BMIs of 30 and above. "That's a huge number of people," says Cummings, one of the statement's authors. "It doubles those eligible."
But many in the medical community do not agree with the summit's conclusions. "We aren't willing to say at the moment that surgery should be the primary option for people who are modestly obese or overweight," says Lebovitz. "Many of us are impressed with the short-term results in some patients, but have some reservations about the lack of long-term results. There isn't a lot known about what happens five to 10 years down the road."
One reason setting the threshold for surgery is so important is that it can help determine who pays the bill: an insurer or the patient. According to the National Institutes of Health, bariatric surgery can typically cost $20,000 to $25,000. Despite evidence showing that bariatric surgery is cost-effective—one 2008 study found that its costs were recouped by insurers just two to four years after surgery because of a reduction in the patient's other medical expenses—insurance coverage is spotty. Even then, bariatric surgery is generally covered only for people with type 2 diabetes and BMIs of 35 and above, the criteria set by the Centers for Medicare and Medicaid Services.
As more surgeries are performed, costs may come down. Or insurance may start footing more bills if definitive research shows surgery is effective for people with type 2 and lower BMIs. Currently, a five-year clinical trial at the Cleveland Clinic is recruiting participants with type 2 diabetes and BMIs of 30 to 35 to test bariatric surgery against standard care. Yet some doctors worry that waiting for the results of this and other studies will deny many people with type 2 diabetes the only treatment that is known to reverse the disease.
"Even though we don't understand exactly what we're doing [that cures type 2]," says Buchwald, "if you have one of the bariatric procedures, you have the opportunity—about an 80 percent or better chance—of not being diabetic anymore. Resolved. You don't need medications. Your pancreas won't burn out, and you'll never need insulin. Do you want a lifetime of management, or do you want to take a small risk to have resolution of your disease? I think the patient is entitled to be given that alternative, to be educated about the possibilities that exist today."
There is good reason to be excited about bariatric surgery; so far the data have been overwhelmingly positive. Yet, it's important not to lose sight of surgery's inherent risks and the uncertainties that remain about long-term complications. The trick is, then, to figure out with your health care team which treatment choices are best, carefully weighing the potential downsides against the hope for a lifetime of health.
Life After Surgery
By Tracey Neithercott
Angie Miller, 43
Nearly three years ago, Angie Miller wouldn't set foot in a gym. At 235 pounds, she had high cholesterol and blood pressure, plus type 2 diabetes. "I did some walking, but I led a pretty sedentary life," she says. "It's hard to go to the gym when you feel like the biggest woman there."
Now Miller, 43, a nurse at the Children's Hospital of Philadelphia, runs half marathons. Why the transformation? It's thanks to a procedure Miller says changed her life: gastric bypass surgery.
Carol Haggerty, 60, can relate. "I really had no life before the surgery. I struggled to get to work, and after work I was just dead," she says. "I was sick all the time." Haggerty, who manages communication devices for Temple University Hospital in Philadelphia, weighed 337 pounds and had type 2 diabetes, sleep apnea, congestive heart failure, high blood pressure, and leg pain that made it tough to walk.
For both Miller and Haggerty, diabetes was a major motivator. After being diagnosed with type 2 in 2006, "I immediately pursued having the surgery," Miller says. She prepped for months—her surgeon required a
psychological evaluation, a dietitian consultation, lung function tests, blood work, and some weight loss—then underwent gastric bypass in July 2007.
Beth Sheldon-Badore, 31
Five days later, she was up and about. By Day 10 she was back at work, though she avoided heavy lifting. She had to stick to a liquid diet for a couple of weeks post-op before graduating to foods like pudding. Three months later, she started eating solids. Now, her weight hovers between 135 and 145, and she's off the five medications she had been taking for her diabetes, cholesterol, and blood pressure.
Miller says her new inclination toward portion control came as a shock. "It was really, really weird," she says. "The first time I went out to dinner, it was very isolating because you take two bites and you're done—and everyone else is eating." She no longer overeats because doing so can cause nausea and vomiting; she only sips a drink while eating so her small stomach isn't full of fluids; and she has given up some favorite foods. "I was a huge coffee drinker before the surgery, and [now] I can't even stand the sight of it," she says.
Most of all, Miller says the weight-loss surgery has boosted her self-esteem. "It gave me the confidence to go for a promotion. I don't think I would have done that before," she says. "I'm much more social now."
Rachel Kapulskey, a 15-year-old high school student who had lap-band surgery in March 2009, points to a boost in energy as one of the surgery's greatest benefits. Kapulskey enrolled in a clinical trial of bariatric surgery in teenagers because she had high cholesterol and an increased risk of diabetes, which runs in her family. After surgery, the 6-foot-tall student dropped from 325 to 225 pounds. "I can honestly say if I hadn't gotten the surgery, I'd be 100 pounds more than [I was] then," she says. "I'd have diabetes."
Rachel Kapulskey, 15
Haggerty has seen similar improvements: She lost 110 pounds with lap-band surgery in January 2008 and no longer has sleep apnea, congestive heart failure, or leg pain. She's off diabetes meds and needs less blood pressure medication. Like Miller, she was amazed at the portions that satisfied her. "Before, it wasn't that I didn't like healthy foods," she says. "They just never filled me."
Haggerty calls lap-band surgery a game-changer. "I have a life again," she says. "I'm out all the time now. I have so much more energy. I sleep better. I'm happier. I'm not depressed about my size."
Still, bariatric surgery isn't without risks. Beth Sheldon-Badore, 31, was 320 pounds but free of diabetes and other risk factors associated with obesity when she underwent gastric bypass in 2004. Now, six years after the surgery, she experiences frequent hypoglycemia that has changed her life. (Her husband, Robert Badore, who had the surgery around the same time, also has hypoglycemia.) "I started out healthy," she says. "I was fat, but I was healthy. It wears on me, and I'm sick of it."
Immediately after the surgery, Sheldon-Badore felt well—even though she says eating certain foods caused her heart to race. "It's sort of a honeymoon feeling," she says. "You don't care how you feel because you're losing weight so quickly." But nine months after getting the surgery, Sheldon-Badore began feeling worse. She researched her condition, then bought a blood glucose meter to confirm her suspicion: Her blood glucose was dropping after meals.
Carol Haggerty, 60
Mount Ephraim, N.J.
Now, she's under doctor's orders to eat frequently and get 15 grams of carbohydrates or less per meal. Refined carbs make her plunge the quickest. "If I eat two frozen waffles, I can guarantee my blood sugar will be 40 [mg/dl]," she says. To blunt the reaction, she eats a mix of protein, fat, and carbs at each meal. She tests often, keeps a glucagon kit on hand, and tries to maintain a blood glucose level of at least 80.
The bottom line: Get informed, be cautious, and understand that surgery can have side effects and that it demands follow-up effort. Miller, Haggerty, and Kapulskey all echo the same mantra: Weight-loss surgery is a tool—not a magic wand. "You also have to make good choices" about diet and exercise, says Kapulskey. "It's not a quick fix, but it's a tool that's amazing."