Often in medicine, a treatment for one condition turns out to be useful for another. Aspirin, for example, started out as a pain reliever and became a go-to pill for heart attack prevention. Similarly, evidence is mounting that surgery to treat weight loss is also a powerful anti-diabetes therapy … but the concept is proving a bit more controversial than aspirin.
Gastrointestinal surgeon Francesco Rubino, MD, would like the medical community to embrace surgery as a viable option for selected patients with type 2 diabetes who don’t respond to medical treatment. To facilitate that, he’s pushing for a categorical name change: Rather than “bariatric” surgery, which refers to weight loss, he believes that if the surgery is being done specifically to treat diabetes and related conditions — regardless of the patient’s body mass index (BMI) — “metabolic” surgery is a more appropriate term.
Of course, the term “metabolic” surgery isn’t new. In 2007 the then-titled American Society for Bariatric Surgery officially changed its name to the American Society for Metabolic & Bariatric Surgery (ASMBS), in recognition of the accumulating data suggesting that gastric bypass and other gut-altering procedures trigger immediate improvements in glycemic control and other metabolic parameters among obese patients with diabetes even prior to weight loss, presumably due to gut hormonal changes. Over the last decade, many individual bariatric surgery centers have added the word “metabolic” to their names.
Yet, Rubino notes, there are still no universally accepted clinical practice guidelines or standards for the practice of “metabolic” surgery, such as pre-operative and follow-up requirements for glucose and hemoglobin A1c testing, or for endocrinology consultation.
“Metabolic surgery isn’t just the technique or procedure you use. It’s also the model of care around it: How you prepare the patient for surgery, what diagnostic evaluations and post-operative strategies you use. All of these things depend on the disease you want to treat, not the BMI,” says Rubino, who has recently moved from New York to London to establish a multidisciplinary metabolic surgery program at King’s College.
But some endocrinologists question the extent to which surgery should be considered as a primary treatment of type 2 diabetes, particularly for patients at the lower end of the obesity scale. “For BMI 30-35 [kg/m2], we don’t know what the risk benefit ratio is,” says Harold E. Lebovitz, MD, professor of medicine at the Division of Endocrinology and Metabolism/Diabetes at the State University of New York, Health Sciences Center at Brooklyn.
Lebovitz points out that while there is currently no effective medical treatment for morbid obesity — therefore, shifting the risk/benefit ratio in favor of “bariatric” surgery — at least 14 medications are available for the treatment of type 2 diabetes, as well as statins and antihypertensives for the related metabolic conditions.
And, he notes, there are risks to bariatric/metabolic surgery, including anastomotic ulceration and leakage, nutritional deficiencies, and death. With regard to treating diabetes, “Th e question is, does metabolic surgery give you better long-term clinical outcomes? The answer is we don’t know.”
What’s in a Name?
The terminology diff erence isn’t trivial, Rubino says. While at Cornell University, he and his colleagues had set up a metabolic surgery program, separate from the already-existing bariatric surgery program. They found distinct diff erences in the patient groups referred to the respective programs: Those referred for metabolic surgery were older, had a lower BMI, were more likely to be male, and more likely to have diabetes, dyslipidemia, and hypertension.
Bariatric surgery patients, in contrast, were primarily younger and female and less likely to have co-existing conditions beyond obesity.
Philip R. Schauer, MD, who was president of the ASMBS in 2007 and spearheaded the society’s name change, agrees with Rubino. “The term ‘bariatric’ had become only partially correct,” he says. “It only means weight loss. That’s a big part of what these operations do, but not the only. These procedures — particularly the bypass-type procedures — have a secondary benefi t.”
According to Schauer, who directs the Cleveland Clinic Bariatric and Metabolic Institute, “Th e term ‘bariatric’ to the public, and even to doctors, is confusing. We’ve struggled in this whole field with this extra stigma and prejudice … [Obesity] is one of the few diseases that still has the connotation of the individual being irresponsible and lazy.”
“I think ‘metabolic’ is a better term, and I think eventually it could replace ‘bariatric,’ because metabolic includes weight loss but goes much beyond weight loss,” says Schauer, who is also professor of surgery at the Cleveland Clinic Lerner College of Medicine of Case Western Reserve University.
Rubino says, “It takes time, because this is a conceptual revolution. It’s a revolution in the way of offering surgical care. Everything changes when you make that shift. It’s not just a semantic issue.”
Interpreting the Data
The success of that shift will depend in large part on the strength of the data. There are now four published randomized clinical trials — three of them including patients with a BMI below 35kg/m2 — demonstrating superiority in achieving diabetes remission with surgery over medical treatment.
Study sizes range from 60 to 218 patients, and follow-up from one to two years. An article published in the April 26, 2012 volume of the New England Journal of Medicine showed that diabetes remission rates ranged from 95% for biliopancreatic-diversion, to 42% to 75% for gastric bypass, while a paper appearing in the January 23, 2008 issue of the Journal of the American Medical Association showed a diabetes remission rate of 73% for adjustable gastric banding.
Rubino says, “Th e bottom line is we now we have randomized clinical trials that have confirmed what we probably knew already from non-randomized observational trials: The efficacy of surgery is of such magnitude that you usually don’t see with medical therapy.”
He points to studies that have identified several possible mechanisms to explain the rapid diabetes remission, including alterations in gut hormones, gut bacteria, bile acids, and nutrient sensing.
But Lebovitz isn’t completely convinced on that point, noting that other studies suggest it’s primarily the weight loss and reduced caloric intake that’s causing the benefit. “This is not a resolved issue,” he says. “Th e reduction in calorie intake occurs immediately. One has to diff erentiate between the actual weight loss and the reduction in food intake.”
Lebovitz cautions that the nutritional deficiencies resulting from the procedures can be significant. Moreover, the data also suggest that patients with a lower BMI and longer diabetes duration are less likely to achieve remission.
“The important issue is, if you have diabetes and a BMI of 33, should you consider surgery as being comparable to medical therapy for the treatment of diabetes?” Lebovitz ponders. “I would say probably at the moment not, because we don’t yet know the long-term effects of the surgery.”
But more information is coming, Schauer says. His group plans to publish three-year and five-year data for their aforementioned study. In the meantime, they just published six-year, non-randomized data from 217 patients with BMIs ranging from 32 to 73, of whom one in four was still in remission (A1c less than 6% and fasting blood glucose below 100 mg/dL off all diabetic medications). Other metabolic benefits were also observed and published in the October 2013 issue of Annals of Surgery.
“It’s a very hot topic … . It’s controversial. A lot of endocrinologists have a tough time reconciling the data with their upbringing on how the disease is managed,” Schauer says. “They were raised on shots and pills, and surgery is very radical. But the data are the data.”
Coverage and Cost-Effectiveness
For now, the question of metabolic surgery for diabetes patients with a BMI below 35kg/m2 is primarily an academic one, since most health plans don’t cover it. In September, the Center for Medicare and Medicaid Services reiterated the 35kg/m2 and above cutoff (plus one obesity comorbidity) for Medicare coverage in a decision memo that also dropped the requirement for certification of bariatric surgical facilities.
Th e Cleveland Clinic, Schauer’s institution, was the first of what is still a very small handful of individual facilities that are experimenting with expanded coverage for metabolic surgery. To qualify, employees with diabetes and a BMI 30-35kg/m2 must be under the care of an endocrinologist, have A1c of 7.5% or above for at least six months despite taking at least three diabetes medications, and must participate in a coordinated care program for diabetes management.
Studies have assessed cost-effectiveness of metabolic surgery in the under-35kg/m2 BMI group, with conflicting results. More data are expected soon, Schauer says.
But Rubino and Lebovitz — who are actually good friends — agree that BMI should not be the sole criterion used to determine which patients should undergo metabolic surgery or whether it should be covered by insurance.
According to Lebovitz, “The problem with BMI is that it doesn’t really tell you about where the fat is and whether you have the metabolic consequences of obesity. You can have two people with the same BMI, but one will have insulin resistance, dyslipidemia, and hypertension, while the other has none of those.”
Indeed, Rubino says, “I’m hopeful that in the future, ongoing studies will tell us the best predictive factors for surgical outcomes.”
Meanwhile, Rubino sees the cost-effectiveness discussion as beside the point. “What is the cost-eff ectiveness of gallbladder surgery? Many of these patients would never go on to pancreatitis. There are cancer surgeries that have dubious effect, but nobody is going to say we don’t cover surgery for cancer. But with bariatric surgery, there is a stigma.”
Hence, the name change. “I don’t think we’re going to change this unless we really understand that we’re doing surgery for a disease such as diabetes. We need to be more consistent with trying to prevent illness and death.”
— Tucker is a freelance medical journalist based in Bethesda, Md.