Table 3

Statements and recommendations

Grade; LoC
Generalities
 1. Given its role in metabolic regulation, the GI tract constitutes a clinically and biologically meaningful target for the management of T2D.Grade U; LoC 100%
 2. There is now sufficient clinical and mechanistic evidence to support inclusion of GI surgery among antidiabetes interventions for people with T2D and obesity.Grade A; LoC 97%
 3. Algorithms for treating T2D should include specific scenarios in which metabolic surgery is considered to be a treatment option in addition to lifestyle, nutritional, and/or pharmacological approaches.Grade A; LoC 92%
 4. The development of an integrated chronic disease care model of lifestyle, nutritional, pharmacological, and surgical approaches is an important priority for modern diabetes care.Grade U; LoC 100%
 5. The clinical community should work together with health care regulators to recognize metabolic surgery as a valid intervention for T2D in people with obesity and to introduce appropriate reimbursement policies.Grade U; LoC 100%
Metabolic surgery versus traditional bariatric surgery
 6. Metabolic surgery—defined here as the use of GI surgery with the intent to treat T2D and obesity—requires the development of a diabetes-based model of clinical practice consistent with international standards of diabetes care.Grade U; LoC 100%
 7. Complementary criteria to the sole use of BMI, the traditional criterion used to select candidates for bariatric surgery, need to be developed to achieve a better patient selection algorithm for metabolic surgery.Grade U; LoC 100%
 8. RYGB, VSG, LAGB, and BPD classic or duodenal switch variant (BPD-DS), are common metabolic operations, each with its own risk-to-benefit ratio. All other metabolic operations are considered to be investigational at this time.Grade A; LoC 91%
 9. Metabolic surgery should be performed in high-volume centers with multidisciplinary teams that understand and are experienced in the management of diabetes and GI surgery.Grade U; LoC 100%
Defining goals and success of metabolic surgery
 10. Although more studies are needed to further demonstrate long-term benefits, evidence exists for GI surgery to be considered as an additional approach beyond lifestyle modifications and current medical therapies to reduce complications of T2D.Grade A; LoC 97%
 11. The aim of metabolic surgery in people with T2D and obesity is to improve their hyperglycemia and other metabolic derangements, while reducing their complications of diabetes, in order to improve their long-term health.Grade A; LoC 97%
Patient selection
 12. Patients’ eligibility for metabolic surgery should be assessed by a multidisciplinary team including surgeon(s), internist(s) or diabetologist(s)/endocrinologist(s), and dietitian(s) with specific expertise in diabetes care. Also, depending on individual circumstances, other relevant specialists could be consulted to evaluate the patient.Grade B; LoC 85%
 13. Contraindications for metabolic surgery include diagnosis of T1D (unless surgery is indicated for other reasons, such as severe obesity); current drug or alcohol abuse; uncontrolled psychiatric illness; lack of comprehension of the risks/benefits, expected outcomes, or alternatives; and lack of commitment to nutritional supplementation and long-term follow-up required with surgery.Grade A; LoC 93%
 14. Metabolic surgery is recommended as an option to treat T2D in patients with the following conditions:
    • Class III obesity (BMI ≥40 kg/m2), regardless of the level of glycemic control or complexity of glucose-lowering regimens.Grade U; LoC 100%
    • Class II obesity (BMI 35.0–39.9 kg/m2) with inadequately controlled hyperglycemia despite lifestyle and optimal medical therapy.Grade A; LoC 97%
 15. Metabolic surgery should also be considered to be an option to treat T2D in patients with class I obesity (BMI 30.0–34.9 kg/m2) and inadequately controlled hyperglycemia despite optimal medical treatment by either oral or injectable medications (including insulin).Grade B; LoC 87%
 16. All BMI thresholds used in these recommendations should be reconsidered depending on the ancestry of the patient. For example, for patients of Asian descent, the BMI values above should be reduced by 2.5 kg/m2.Grade B; LoC 86%
 17. Given the lack of level-1 evidence involving the effects of metabolic surgery on T2D in adolescent patients, the DSS-II committee feels a recommendation for use of GI surgery in this population is inappropriate at present. However, the committee does consider this a high priority for future research.Grade U; LoC 100%
Preoperative workup
 18. Preoperative patient evaluation should include assessment of endocrine, metabolic, physical, nutritional, and psychological health.Grade U; LoC 100%
 19. Preoperative evaluation should include a combination of routine clinical tests and diabetes-specific metrics. The following tests are recommended by the DSS-II expert group:Grade A; LoC 98%
    • Standard preoperative tests used for GI surgery at individual providers’ institutions.
    • Recent tests to characterize current diabetes status—for example, but not limited to, HbA1c, fasting glucose, lipid profile, and tests for retinopathy, nephropathy, and neuropathy.
    • Tests to distinguish T1D from T2D (fasting C-peptide; anti-GAD or other autoantibodies).
 20. In order to reduce the risk for postoperative infection due to hyperglycemia, an attempt should be made to improve glycemic control before surgery.Grade A; LoC 95%
Choice of procedure
 21. RYGB is a well-standardized surgical procedure, and among the four accepted operations for metabolic surgery, it appears to have a more favorable risk-benefit profile in most patients with T2D.Grade U; LoC 100%
 22. Although longer-term studies are needed, current data suggest that VSG is an effective procedure that results in excellent weight loss and major improvement of T2D, at least in the short to medium term (1–3 years) in which outcomes have been measured in RCTs. It could be a valuable option to treat diabetes, especially in patients for whom concerns exist about the risk of operations that involve bowel diversion.Grade B; LoC 80%
 23. LAGB is effective in improving glycemia in patients with obesity and T2D, to the degree that it causes weight loss. The procedure, however, is associated with greater risk for reoperation/revision compared with RYGB due to failure or band-related complications, e.g., slippage/migration, erosion, etc.Grade B; LoC 85%
 24. Although clinical evidence suggests that BPD/BPD-DS may be the most effective procedure in terms of glycemic control and weight loss, the operation is associated with significant risk of nutritional deficiencies, making its risk-benefit profile less favorable than that of the other bariatric/metabolic procedures for most patients. BPD/BPD-DS should be considered only in patients with extreme levels of obesity (e.g., BMI >60 kg/m2).Grade B; LoC 83%
Postoperative follow-up
 25. After surgery, patients should continue to be managed by multidisciplinary teams including diabetologists/endocrinologists, surgeons, nutritionists, and nurses with specific diabetes expertise.Grade A; LoC 98%
 26. Postoperative follow-up should include surgical and nutritional evaluations at least every 6 months, and more often if necessary, during the first 2 postoperative years and at least annually thereafter.Grade U; LoC 100%
 27. Unless patients have a documented, stable condition of nondiabetic glycemia, glycemic control should be monitored with at least the same frequency as in standard diabetes care of nonoperated patients.Grade U; LoC 100%
 28. In patients who have reached stable normalization of hyperglycemia for at least 6 months, monitoring of glycemic control should be performed with the same frequency as recommended for patients with prediabetes because of the potential for relapse.Grade A; LoC 95%
 29. Patients with a stable condition of nondiabetic glycemia for less than 5 years should be monitored for complications of diabetes at the same frequency as before remission. Once remission reaches the 5-year mark, monitoring of complications can be done at a reduced frequency, depending on the status of each complication. Complete cessation of screening for a particular complication should be considered only if nondiabetic glycemia persists and there is no history of that complication.Grade B; LoC 85%
 30. Within the first 6 months after surgery, patients should be carefully evaluated for glycemic control and antidiabetes medication(s) tapered according to the professional opinion of the physician(s). Further medical treatment of T2D after this initial 6-month period should be dosed accordingly, but not discontinued until laboratory proof of stable glycemic normalization is obtained. Stable nondiabetic glycemia (i.e., HbA1c in the normal range) should be documented for at least two 3-month HbA1c cycles (6 months in total) before considering complete withdrawal of glucose-lowering drugs, although withdrawal of certain frontline medications (e.g., metformin) should be considered more carefully.Grade B; LoC 82%
 31. In the event of plasma glucose levels rapidly approaching the normal range early postoperatively, appropriate adjustments to medical therapy (medication types and dosage) should be implemented to prevent hypoglycemia. Metformin, thiazolidinediones, GLP-1 analogs, DPP-4 inhibitors, α-glucosidase inhibitors, and SGLT2 inhibitors are suitable drugs for early postoperative diabetes management due to their low risk of inducing hypoglycemia.Grade A; LoC 98%
 32. Ongoing and long-term monitoring of micronutrient status, nutritional supplementation, and support must be provided to patients after surgery, according to guidelines for postoperative management of metabolic/bariatric surgery by national and international societies (for example, AACE/TOS/ASMBS, IFSO, BOMSS).Grade U; LoC 100%
  • Grade U = 100% agreement (unanimous); grade A = 89–99% agreement; grade B = 78–88% agreement; grade C = 67–77% agreement. AACE, American Association of Clinical Endocrinologists; ASMBS, American Society for Metabolic and Bariatric Surgery; BOMSS, British Obesity & Metabolic Surgery Society; DPP-4, dipeptidyl peptidase 4; GLP-1, glucagon-like peptide 1; IFSO, International Federation for the Surgery of Obesity and Metabolic Disorders; LoC, level of consensus; SGLT2, sodium–glucose cotransporter 2; TOS, The Obesity Society.