New field of medicine: Diabetes surgery

Summit releases consensus statement

A first-of-its-kind consensus statement on diabetes surgery is published online in the Annals of Surgery. The report illustrates the findings of the first international consensus conference — Diabetes Surgery Summit (DSS) — where an international group of more than 50 scientific and medical experts agreed on a set of evidence-based guidelines and definitions that are meant to guide the use and study of gastrointestinal surgery to treat Type 2 diabetes. The document is considered to be the foundation of diabetes surgery as a medical discipline of its own.

The Diabetes Surgery Summit was held in Rome under the auspices of 22 international medical and scientific organizations, including the American Diabetes Association and the American Society for Metabolic and Bariatric Surgery. A draft of the DSS consensus statement was critically reviewed by official representatives of these organizations during the First World Congress on Interventional Therapies for Type 2 Diabetes, organized by New York — Presbyterian Hospital/Weill Cornell Medical Center.

Bariatric surgery is only available as a treatment for severe obesity, defined as having a body mass index (BMI) of 35 kg/m2 or more, according to National Institutes of Health (NIH) guidelines established in 1991. The DSS consensus statement acknowledges that the cutoff is arbitrary and not supported by scientific evidence, and it recognizes the need to use more appropriate criteria for surgery in patients with diabetes.

"With an emphasis on caution and patient safety, the DSS position statement boldly advances a revolutionary concept: the legitimacy of gastrointestinal surgery as a dedicated treatment for Type 2 diabetes in carefully selected patients," explains lead author Francesco Rubino, MD, director of the gastrointestinal metabolic surgery program at NewYork — Presbyterian Hospital/Weill Cornell Medical College and associate professor of surgery at Weill Cornell Medical College. "The recommendations from the Diabetes Surgery Summit are an opportunity to improve access to surgical options supported by sound evidence, while also preventing harm from inappropriate use of unproven procedures."

The article in the Annals of Surgery, co-authored by the DSS organizers on behalf of 50 voting delegates, summarizes the mounting body of evidence showing that bariatric surgery effectively reverses Type 2 diabetes in a high proportion of morbidly obese patients, sometimes within weeks or even days, well before these patients have lost a significant amount of body weight.

Rubino's experimental studies demonstrated that gastric bypass surgery can improve Type 2 diabetes through direct anti-diabetic mechanisms and not solely as a result of weight loss, a finding that has been corroborated by other researchers with experimental and human investigations. Based on these data, the 50 international delegates of the summit achieved strong consensus that certain intestinal bypass operations engage anti-diabetes mechanisms beyond those related to reduced food intake and body weight. David E. Cummings, MD, an endocrinologist at the Diabetes & Obesity Center of Excellence of the University of Washington in Seattle and senior author of the consensus document, said, "This and the remarkable clinical efficacy of gastrointestinal surgery justify considering it as a specific diabetes intervention, rather than viewing diabetes remission merely as a collateral effect of weight loss surgery. That understanding may also usher in a new era of drug discovery and development based on the identification of the metabolic pathways and mechanisms that drive the disease."

Philip R. Schauer, MD, of the Bariatric and Metabolic Institute, Lerner College of Medicine, Cleveland Clinic, another co-author of the report, said, "The diabetes surgery consensus statement, together with the combined American Diabetes Association/European Association for the Study of Obesity guidelines for treating diabetes published in January 2009, are major steps forward toward leading diabetes experts in recognizing the important role that surgery may play in the treatment of diabetes."

The National Institutes of Health (NIH) already has responded to the document's call for research, issuing several recent Requests for Applications for projects focusing on the effects of gastrointestinal surgery on diabetes, including patients with a BMI as low as 30 kg/m2 (i.e., with only mild obesity). Co-author Lee M. Kaplan, MD, PhD, of the Boston Obesity and Nutrition Research Center, Harvard Medical School, Massachusetts General Hospital, said, "That's in line with the recommendations of the Rome summit. Understanding the mechanisms of action of surgery on diabetes is a unique opportunity to advance the treatment of the disease."

The BMI debate

In its position statement, the Diabetes Surgery Summit states: "Surgery should be considered for the treatment of Type 2 diabetes" in patients with a BMI of 35 or more "who are inadequately controlled by lifestyle and medical therapy." The statement goes on to state that diabetes surgery also might be appropriate for treatment of people with Type 2 diabetes and merely mild-to-moderate obesity (BMI 30-35).

This statement goes beyond parameters established by the NIH for bariatric surgery in 1991, which reserved bariatric surgery for people with a BMI of 35 or more with an obesity-related condition, or a BMI of 40 or more with or without any obesity-related condition. These parameters still are adhered to by most insurance companies in determining coverage of the surgery.

Schauer said, "The science of diabetes, obesity, and surgery has significantly advanced since 1991, and the evidence suggests that a precise BMI cutoff of 35 is not a good predictor of whether or not surgery will induce diabetes remission or improvement."

BMI is an inadequate measure as a stand-alone criterion for patient selection, Rubino said. "Once a patient has full-blown diabetes, BMI can't accurately predict that patient's cardiovascular risk, much less who will and won't be likely to benefit from surgery," he said. "It simply doesn't make sense to offer the surgical option to a patient with a BMI of 35 and deny it to one with a BMI of 34, especially if the latter patient has more severe diabetes. The health risks associated with a BMI of 35 may vary, too, with gender, race, and ethnicity, compounding its inadequacy as a parameter for patient selection. High up on our research agenda is the search for new eligibility criteria that should be based on diabetes-specific metrics and include patient's history, metabolic profile and disease severity."

The DSS consensus document emphasizes the importance of multidisciplinary approaches to guide the development of the discipline of diabetes surgery from the outset. A specific recommendation of the Diabetes Surgery Summit called for the establishment of a multidisciplinary, international taskforce that includes endocrinologists, surgeons, clinical and basic investigators, and bioethicists, among others.

The International Diabetes Surgery Taskforce has been established as a nonprofit organization that will cooperate with existing professional societies, government agencies, and patient advocacy groups in order to expand and disseminate evidence-based knowledge of diabetes surgery.