The American Society for Metabolic and Bariatric Surgery (ASMBS) and International Federation for the Surgery of Obesity and Metabolic Disorders (IFSO) have released new guidelines on who should undergo bariatric surgery — the first major update to guidelines established by the U.S. National Institutes of Health (NNIH) in 1991. The new guidelines were published in the journal Surgery for Obesity and Related Diseases.
Research has shown that there are many potential health benefits from undergoing bariatric surgery in people with obesity, especially in people with type 2 diabetes. The surgery has been shown to promote remission of both type 2 diabetes and prediabetes — meaning that your blood glucose levels return to the normal range without taking any glucose-lowering medications. It has also been shown to reduce levels of liver fat in people with type 2 diabetes, potentially counteracting the higher risk seen in people with type 2 for nonalcoholic fatty liver disease (NAFLD). The surgery may also lower the risk for diabetic retinopathy (eye disease) in people with type 2 diabetes. Regardless of a person’s diabetes status, bariatric surgery is linked to improved mobility and less chronic pain, healthier lifestyle behaviors, and a lower risk of dying earlier.
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The authors of the latest guidelines note that the NIH’s 1991 guidelines have been widely used to this day to establish who is eligible for bariatric surgery. In those earlier guidelines, researchers recommended that nonsurgical weight-loss programs be the first line of treatment for severe obesity, and that a multidisciplinary health care team should evaluate people who may be candidates for bariatric surgery. They also established a body-mass index (BMI, a measure of body weight that takes height into account) of 40 or higher, or a BMI of 35 or higher along with related severe health problems, as the threshold for eligibility for the surgery.
To establish the new guidelines, the researchers reviewed hundreds of studies that have been published on bariatric surgery in the last 30 years — studies that have shed light on not just the potential benefits of bariatric surgery, but also what happens in the body in obesity. Obesity, the authors write, is now understood as a chronic disease involving a low-grade inflammatory state — and this inflammatory state is linked to the chronic health conditions, including type 2 diabetes.
At the same time, there are now many high-quality studies on the long-term effects of undergoing bariatric surgery. The authors note that the surgery is now firmly established as an effective and lasting treatment for severe obesity and related health conditions — and that study after study has shown that bariatric surgery is linked to better outcomes than nonsurgical treatments. The surgery is also very safe, with the death rate in the wake of surgery somewhere in the range of 0.03% to 0.2%. The risks linked to bariatric surgery have gone down over time as doctors have performed more and more procedures, and due to the adoption of minimally invasive laparoscopic and robot-assisted approaches.
What the new bariatric surgery guidelines recommend
The new guidelines recommend bariatric surgery for anyone with a BMI of 35 or higher, regardless of whether the person has related severe health problems. They also state that the surgery should be considered for people with metabolic diseases — such as type 2 diabetes — and a BMI of 30 to 34.9, which is considered to be the range of non-severe obesity. For people of Asian descent, there are different recommended thresholds, based on evidence that this population experiences poor health effects at lower levels of excess body weight. The guidelines state that bariatric surgery is recommended for people of Asian descent with a BMI of 27.5 or higher, and should be considered for people of Asian descent with metabolic diseases and a BMI between 25 and 27.4.
The new guidelines also state that “appropriately selected” children and adolescents should be considered for bariatric surgery, based on a large body of evidence showing that obesity starting at a younger age can lead to especially poor long-term health consequences. In fact, the authors note, there is evidence suggesting that the benefits of bariatric surgery on type 2 diabetes and high blood pressure may be even greater for adolescents than for adults.
It’s worth noting that the vast majority of studies supporting the new guidelines on bariatric surgery were conducted before the approval last year of Wegovy (semaglutide), which has been hailed as a “groundbreaking” weight-loss drug that is much more effective than previous drugs — with participants who took the drug for 48 weeks losing an average of 20.5% of their body fat mass in one major study. It’s possible that future research — including comparison studies between Wegovy or other new weight-loss drugs and bariatric surgery — will lead to revised recommendations on bariatric surgery eligibility.
Want to learn more about bariatric surgery and type 2 diabetes? Read “Is Bariatric Surgery for You?” and “Bariatric Surgery and Diabetes: Questions and Answers.”