Treatment Algorithm for Type 2 Diabetes: Metabolic / Bariatric Surgery Indicated for Many Patients
Author: Cassie Story, RDN; Bariatric Dietitian
With national trends increasing in the incidence of people affected by obesity and type 2 diabetes (T2D) medical societies and associations are working vigorously to establish evidenced based guidelines in an effort to improve treatment decisions. During the 2nd Diabetes Surgery Summit (DSS-II) new global guidelines, which were published in June of this year, were developed to provide clinicians and policymakers with treatment considerations for people with T2D, and for the first time, included metabolic / bariatric surgery. 
For many in the medical community, outside bariatric surgery, metabolic / bariatric surgery is often viewed simply as a weight loss procedure. However, evidence for the safety and efficacy of metabolic / bariatric surgery on long term health outcomes continues to be published.  In spite of that, questions remain regarding the exact mechanism through which metabolic/ bariatric surgery improves blood sugar control;  as many patients experience improvement in blood sugar levels independent of weight loss immediately following metabolic / bariatric surgery.
Within these guidelines the recommendation for metabolic / bariatric surgery was established for the following patient populations: 2
- Class III Obesity (BMI greater than or equal to 40 kg/m²) – Expedited assessment for surgery is recommended
- Class II Obesity (BMI between 35 and 39.9 kg/m²) – with adequate glycemic control, surgery may be considered; also offer appropriate lifestyle and medical treatments
- Class I Obesity (BMI between 30 and 34.9 kg/m²) – when hyperglycemia is inadequately controlled by lifestyle and medical therapy
- Special recognition should be given to Asian patients with type 2 diabetes at a lower BMI than other populations (lowered 2.5 kg/m²) for each category
These recommendations were based on a review of 11 randomized clinical trials that showed surgical intervention can either: reduce blood sugar levels to below diabetic thresholds, or maintain glycemic control despite a reduction in medication usage. 1 A meta-analysis, involving 19 studies and over 4,000 patients, reported a T2D resolution rate (defined by normal HbA1C levels, without medications) of 78% following metabolic / bariatric surgery. 
Lifestyle and medical interventions are necessary for all patients along the spectrum of obesity and T2D. Note that patients who have Class 1 and Class II Obesity should be referred to surgery only after lifestyle and medical interventions have been tried. It is important for all patients to understand that for long term success, with or without metabolic /bariatric surgery, changes in lifestyle are necessary.
Further studies are needed regarding long-term remission rates as well as lifestyle interventions to help facilitate continued blood sugar control once metabolic / bariatric surgery has been performed. There is data to suggest that some patients will experience remission of hyperglycemia as they progress after surgery. Long term nutritional interventions for patients who have had metabolic / bariatric surgery include a focus on a high protein diet, which may also be beneficial in helping to control hyperglycemia when balanced with an appropriate macronutrient distribution such as 40% carbohydrate, 30% protein, and 30% fat.
While the safety of metabolic surgeries is now comparable to a cholecystectomy, with mortality rates averaging 0.3%, the long term complications including nutritional deficiencies, weight regain, and reappearance of obesity related comorbidities remains.
For this reason it is critical that patients who receive metabolic / bariatric surgery work closely with their medical team to improve their long term success. New science will continue to emerge regarding the vitamin and mineral supplementation needs and optimal dietary patterns to follow to maintain long term blood sugar control as well as optimal health outcomes following metabolic / bariatric surgery.
- Alexandria, V. Consensus from Diabetes Organizations Worldwide: Metabolic Surgery Recognized as a Standard Treatment Option for Type 2 Diabetes. American Diabetes Association Web site. May 24, 2016. Accessed September 14, 2016.
- Rubino, F, Nathan D, Eckel, R et al. Metabolic Surgery in the Treatment Algorithm for Type 2 Diabetes: A Joint Statement by International Diabetes Organizations. Diabetes Care. 2016;39(6):861-877.
- Schauer, P, Mingrone G, Ikramuddin S, et al. Clinical Outcomes of Metabolic Surgery: Efficacy of Glycemic Control, Weight Loss, and Remission of Diabetes. Diabetes Care. 2016;39:902-911.
- Buchwald H, Estok R, Fahrbach K, et al. Weight and type 2 diabetes after bariatric surgery: systemic review and meta-analysis. Am J Med. 2009;122:248-256.e5.
- Arterburn DE, Courcoulas AP. Bariatric surgery for obesity and metabolic conditions in adults. BMJ. 2014;349:g3961.