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Metabolic surgery for treating type 2 diabetes mellitus: Now supported by the world's leading diabetes organizations

July 1, 2017 | Cleveland Clinic Journal of Medicine
Philip R. Schauer, MD ; Zubaidah Nor Hanipah, MD ; Francesco Rubino, MD
Author and Disclosure Information

Philip R. Schauer, MD
Director, Bariatric and Metabolic Institute, Cleveland Clinic

Zubaidah Nor Hanipah, MD
Bariatric and Metabolic Institute, Cleveland Clinic; Department of Surgery, Faculty of Medicine and Health Sciences, University Putra Malaysia, Selangor, Malaysia

Francesco Rubino, MD
Department of Metabolic and Bariatric Surgery, Diabetes and Nutrition Science Division, King’s College London, UK

Correspondence: Philip Schauer, MD, Director, Bariatric and Metabolic Institute, M61, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195; schauep@ccf.org

Dr. Schauer reported research grant support from Ethicon, Medtronic, and Pacira Pharmaceuticals; consulting fees from The Medicines Company, AMAG Pharmaceuticals, GI Dynamics, and Neurotronics; honoraria for speaking from Novo Nordisk; and ownership interest in SE HQC LLC. Dr. Nor Hanipah reported no financial interests or relationships that pose a potential conflict of interest with this article. Dr. Rubino reported research grant support from NIMR (UK Gov) and Ethicon; consulting fees from Fractyl and GI Dynamics; and honoraria for speaking from Medtronic and Ethicon.

ABSTRACT

The term metabolic surgery describes bariatric surgical procedures used primarily to treat type 2 diabetes and related metabolic conditions. Originally, bariatric surgery was used as an alternative weight-loss therapy for patients with severe obesity, but clinical data revealed its metabolic benefits in patients with type 2 diabetes. Metabolic surgery is more effective than lifestyle or medical management in achieving glycemic control, sustained weight loss, and reducing diabetes comorbidities. Perioperative adverse events are similar to other gastrointestinal surgeries. New guidelines for type 2 diabetes expand use of metabolic surgery to patients with a lower body mass index.

KEY POINTS

  • Randomized clinical trials have shown that metabolic surgery is statistically superior to medical treatment in achieving targeted glycemic levels along with improvements in weight loss, remission of metabolic syndrome, reduction in medications, and improvements in lipid levels.
  • The safety of metabolic and bariatric surgery has significantly improved with the advent of laparoscopic surgery, resulting in complication profiles similar to those of cholecystectomy and appendectomy.
  • Metabolic surgery is now recommended as standard treatment option for type 2 diabetes in patients with body mass index levels as low as 30 kg/m2.

METABOLIC SURGERY: ADVERSE EVENTS

Surgical complications

Postoperative complication rates of surgical procedures in patients with type 2 diabetes mellitus: US data.
Reprinted with permission from John Wiley & Sons (Aminian A, et al. How safe is metabolic/diabetes surgery? Diabetes Obes Metab 2015; 17:198–201.) ©2014 John Wiley & Sons Ltd.
Figure 3. Postoperative complication rates of surgical procedures in patients with type 2 diabetes mellitus: US data. CABG = coronary artery bypass graft; RYGB = Roux-en-Y gastric bypass
Overall, rates of perioperative morbidity and mortality of bariatric surgery are similar to those of common, relatively low-risk abdominal procedures such as cholecystectomy and appendectomy. The NIH-supported Longitudinal Assessment of Bariatric Surgery study reported a low 30-day mortality rate of 0.3% in 4,776 patients and a 4.3% incidence of major adverse events in the early postoperative period.45 A study from the American College of Surgeons (> 65,000 patients) showed that laparoscopic RYGB had perioperative morbidity and mortality rates of 3.4% and 0.3%, respectively, similar to those for laparoscopic cholecystectomy (3.7% and 0.7%) and appendectomy (4.5% and 0.5%) (Figures 3 and 4) and much lower than for laparoscopic colectomy (12.0% and 1.7%).46
Mortality rates of 8 procedures in patients with diabetes (2008–2012).
Reprinted with permission from John Wiley & Sons (Aminian A, et al. How safe is metabolic/diabetes surgery? Diabetes Obes Metab 2015; 17:198–201.) ©2014 John Wiley & Sons Ltd.
Figure 4. Mortality rates of 8 procedures in patients with diabetes (2008–2012). CABG = coronary artery bypass grafting; RYGB = Roux-en-Y gastric bypass
Table 2 summarizes early and late postoperative complications of metabolic surgery. Although rare (< 1%), cardiopulmonary complications such as myocardial infarction and pulmonary embolism are the major causes of mortality, representing 70% of all perioperative deaths.45 Intestinal leakage at the anastomosis or staple line is the most serious early surgical complication after RYGB (0.1%–5.6%) and may potentially lead to peritonitis. Bowel obstruction (0.5%–2%) and marginal ulcers (1%–5%) may also occur months to years after RYGB.47,48 Staple-line leakage (1%–5%) and gastric stenosis (1%–5%) are the most common surgical complications of SG.17

For BPD-DS, perioperative complications are similar to those for RYGB. Although LAGB is safe, with a very low mortality rate (< 0.3%), late complications such as band slippage, erosion, migration, and surgical port infection occur in about 20% of patients.49 Reoperation for poor weight loss or complications after LAGB is common, occurring in approximately 50% of patients.50 In general, patients at higher risk of complications after bariatric surgery are those with high BMI, older age, multiple comorbidities, smoking, or previous revisional operations; men are also at higher risk.45

Nutritional deficiencies

Postoperative nutritional deficiencies are typically associated with diminished nutrient intake or the malabsorptive effect of bariatric procedures. They are more common after RYGB and BPD-DS and less common after SG and LAGB. In addition, there is a high prevalence of nutritional deficiencies (35%–80%) in patients seeking bariatric surgery; thus, poor preoperative nutrition may be a factor in the development of postoperative deficiencies. Common preoperative nutrient deficiencies are vitamin A (11%), vitamin B12 (13%), vitamin D (40%), zinc (30%), iron (16%), ferritin (9%), selenium (58%), and folate (6%).51 Recommendations are to assess for these deficiencies and correct any identified before surgery.

Mild anemia after bariatric procedures is common, occurring in 15% to 20% of cases, and it is believed to result from reduced absorption of iron and B12, as well from pre-existing iron deficiency anemia in premenopausal patients.52 Deficiencies in trace minerals (selenium, zinc, and copper) and vitamins (B12, B1, A, E, D, and K) can occur after bariatric procedures, especially after BPD-DS.53 Nutrient deficiencies can be prevented or corrected with appropriate vitamin, iron, and calcium supplementation.54 

Bone mineral density may decrease after bariatric surgery (14% in the proximal femur).55 Reduced mechanical loading after weight loss, reduced consumption and malabsorption of micronutrients (calcium, vitamin D), and neurohormonal alterations are potential underlying mechanisms of bone mineral density reduction after bariatric surgery. Rates of bone fracture and osteoporosis are not well delineated, raising questions about whether bone loss after bariatric surgery is clinically relevant or a functional adaptation to skeletal unloading. However, the extreme malabsorptive procedures of BPD-DS have been associated with severe calcium and vitamin D deficiencies, leading to decreased bone mineral density and osteoporosis.

Protein malnutrition also can occur after these extreme malabsorptive procedures. Patients require postoperative oral protein supplementation (80–100 g/day) and lifelong monitoring for nutritional complications after these procedures.56

Additional complications

Other late complications of bariatric surgery that are less clear in incidence and cause include kidney stones, alcohol abuse, depression, and suicide. One study of patients after RYGB (N = 4,690) reported a significantly higher prevalence of kidney stones than in obese controls: 7.5% vs 4.6%, respectively.57 Proposed causes of kidney stone formation following bariatric surgery include hyperoxaluria, hypocitraturia, and elevated urine acidity.58

The prevalence of alcohol-use disorder after bariatric surgery ranges from 7.6% to 11.8% and appears to be higher in patients with a history of alcohol use.59 Paradoxically, while bariatric surgery has been shown to significantly decrease depression,60 some studies suggest that a slight increase in the risk of suicide may occur,61 while others do not.62 A recent review concluded that accurate rates of suicide after bariatric surgery are not known, but practitioners should be aware of this concern and appropriately screen and counsel their patients.63

Although the 12 RCTs reported in Table 1 were not powered to detect differences in treatment-related complications, the overall rates of complications were consistent with those in observational studies.9 The most common surgical complications were anemia (15%), need for reoperation (8%), and GI (5%–10%). The 30-day surgical mortality rate was 0.2% (1 death) among the 465 surgical patients. Complications were not limited to the surgical patients. In the medical-treatment control group of the STAMPEDE trial,30 anemia (16%) and weight gain (16%) were common. Investigators reported challenges with medication compliance, including adverse effects leading to discontinuation of medications. Mild hypoglycemia was common, with no significant differences between the surgical and medical treatment groups.

METABOLIC SURGERY: COST EFFECTIVENESS

The cost of bariatric procedures varies considerably but, in general, ranges from $20,000 to $30,000, similar to the cost of cholecystectomy, hysterectomy, and colectomy. Retrospective analyses and modeling studies indicate that metabolic surgery is cost-effective and may present a cost savings in patients with type 2 DM, with a break-even time between 5 and 10 years.64,65 The cost savings, largely based on assumptions of long-term effectiveness and safety, result from reductions in medication use, outpatient care costs, and long-term complications of type 2 DM.

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