Did you notice an update to the American Diabetes Association (ADA) treatment algorithm? It now includes metabolic surgery as a treatment option for people with type 2 diabetes and obesity who do not respond to conventional treatment. Considering that nearly 90% of people with type 2 diabetes also have obesity, metabolic surgery is relevant for millions of people. What is metabolic surgery and how did it make its way into the ADA algorithm?
Metabolic surgery refers to gastrointestinal operations, primarily Roux-en-Y gastric bypass (RYGB), biliopancreatic diversion with duodenal switch (BPD-DS), and sleeve gastrectomy (SG), that are used with the intent to treat diabetes and metabolic dysfunctions, including obesity. You might know it by a different name: bariatric or weight loss surgery. However, these procedures do so much more than facilitate weight loss.
The first published account of improvement in diabetes following a gastrointestinal surgery was in the 1920s; however, this phenomenon didn’t gain much attention until a case series was published in 1995. It demonstrated that over 80% of the patients with type 2 diabetes who had RYGB had improvements in their glucose metabolism, many before significant weight loss occurred. Since then, biological and clinical evidence supporting the effect of metabolic surgery on diabetes has accumulated but it wasn’t accepted as a safe and efficacious treatment. This led to the 1st Diabetes Surgery Summit in Rome in 2007 which acknowledged the potential for metabolic surgery and resulted in a call for randomized control trials (RCTs).
The group reconvened in 2015 with multiple RCTs supporting metabolic surgery as the superior treatment for glycemic management and reduction in cardiovascular risk factors when compared with medical and lifestyle interventions. Analysis of the RCTs demonstrated a median HbA1c reduction of 2.0% for surgery versus 0.5% for conventional therapies. These significant results led to endorsements of metabolic surgery from 45 international organizations, including the ADA, International Diabetes Federation (IDF), Diabetes UK (DUK), Chinese Diabetes Society (CDS), and Diabetes India (DI).
Metabolic surgery has a complex effect on the gastrointestinal tract. Mechanisms of diabetes improvement include alterations of gut hormones, neural signaling, nutrient sensing, microbiome, and bile acid signaling. These mechanisms mediate improved glucose homeostasis through β-cell functioning, insulin sensitivity, and glucose production and utilization. While any surgery has risks, metabolic surgery is about as safe as gallbladder surgery. It does have long-term implications, including the risk of nutrient deficiencies, which require lifelong follow-up care from a multidisciplinary team that includes a Registered Dietitian.
Based on NIH guidelines developed in 1991, qualification for metabolic surgery is the presence of type 2 diabetes with a body mass index (BMI) of at least 35 kg/m². However, evidence supports the use of metabolic surgery in people with type 2 diabetes with a BMI as low as 30 kg/m², or 27.5 kg/m² in people of Asian descent. Predictors of diabetes remission are diabetes duration of less than 8 years, lower preoperative fasting glucose, and use of a procedure with intestinal diversion, such as RYGB and BPD-DS. This supports the push for early recognition of candidates before β-cell function is greatly diminished. Even patients that do not go into remission following surgery stand to gain long-term improvements in their glycemic management, weight-related comorbidities, and overall quality of life.
While metabolic surgery has finally earned its place in the ADA treatment algorithm, it continues to be an underused therapy. Many factors contribute to this including lack of knowledge and comfort on the part of both clinicians and patients and lack of insurance coverage in many states. Certified Diabetes Educators (CDEs) are in a prime position to recognize and refer candidates for surgery in the same way that they discuss other therapies within the treatment algorithm. Remember, early recognition of candidates enhances the likelihood of diabetes remission. Embracing metabolic surgery as a therapy for type 2 diabetes will help millions of people to live longer and healthier lives.
Want to learn more about metabolic surgery and its impact on type 2 diabetes?
Visit http://care.diabetesjournals.org/content/diabetes-care-online-collections to access the June 2016 issue of Diabetes Care which featured a special topic collection on metabolic surgery.
- Batterham RL and Cummings DE. Mechanisms of Diabetes Improvement Following Bariatric/Metabolic Surgery. Diabetes Care, 2016; 39(6): 893-901. https://doi.org/10.2337/dc16-0145
- Cummings DE and Cohen RV. Bariatric/Metabolic Surgery to Treat Type 2 Diabetes in Patients With a BMI <35 kg/m2. Diabetes Care, 2016; 39(6): 924-933. https://doi.org/10.2337/dc16-0350
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