Diabetes societies endorse 'metabolic surgery'

By Eleanor McDermid

An "unprecedented" number of societies have endorsed guidelines recommending metabolic surgery for patients with diabetes - and not just for patients with severe obesity.

The new guidelines recommend surgery in all patients with a body mass index (BMI) of at least 40.0 kg/m² and in those with a BMI 35.0-39.9 kg/m² who have hyperglycaemia despite optimal lifestyle and medical treatment.

But they also present it as an option for patients right down to a BMI of 30.0 kg/m² if hyperglycaemia cannot be controlled with optimal therapy. And the lowest BMI threshold falls to 27.5 kg/m² in Asian patients.

The guideline writers, led by Francesco Rubino (King's College London, UK), note that surgery is cost-effective, despite the large upfront costs, working out at around US $3000-6000 per quality-adjusted life-year (QALY), which is well below the threshold usually adopted to determine cost-effectiveness for clinical practice and also well below the cost per QALY of intensive medical treatment to achieve glycaemic or lipid control.

But the team stresses the need for "the development of a new, disease-based model of practice", given that bariatric surgery patients tend to be young, female and with low rates of diabetes, contrasting with the older, male population with Type 2 diabetes who are considered for metabolic surgery, with implications for outcomes and cost effectiveness.

The guidelines emerged from the international consensus conference the 2nd Diabetes Surgery Summit and have, to date, been endorsed by 45 worldwide medical and scientific societies. To complement the new recommendations, which are published in Diabetes Care, the current issue of the journal carries 11 related review articles providing the latest information on topics ranging from the mechanisms by which bariatric surgery improves glucose metabolism to the influence of ethnicity and barriers to appropriate use of metabolic surgery.

In a linked commentary, William Cefalu (Louisiana State University, Baton Rouge, USA) and co-authors say the guidelines are a response to "a large body of evidence" that surgical interventions geared at obesity "can improve glucose homeostasis more effectively than any known pharmaceutical or behavioral approach".

And with the guidelines endorsed by "an unprecedented array of societies representing diverse medical and surgical specialties from around the world", the recommendations "can serve as a global reference" for gastrointestinal surgery in patients with Type 2 diabetes.

Among a raft of other statements, the guidelines outline contraindications to metabolic surgery, including diagnosis of Type 1 diabetes, drug or alcohol abuse, uncontrolled psychiatric illness, and inability to commit to taking long-term nutritional supplements and attending follow-up.

The guideline writers also outline knowledge gaps, including factors predicting glycaemic control, outcomes in patients who are overweight or only mildly obese, the relative merits of different surgical procedures and patient outcomes beyond 5 years. And they say that the effectiveness of surgery in adolescents should be a priority area for future research, given the current lack of high-quality evidence.

Source: Diabetes Care 2016; 39: 857-860, 861-877

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