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Bariatric surgery for type 2 diabetes: Weighing the impact for obese patients

Cleveland Clinic Journal of Medicine. 2010 July;77(7):468-476 | 10.3949/ccjm.77a.09135
July 1, 2010|Type 2 Diabetes ICYMI
Sangeeta R. Kashyap, MD Patrick Gatmaitan, MD;Stacy Brethauer, MD;Philip Schauer, MD
Author and Disclosure Information

Sangeeta R. Kashyap, MD
Department of Endocrinology, Diabetes, and Metabolism, Cleveland Clinic

Patrick Gatmaitan, MD
Bariatric and Metabolic Institute, Cleveland Clinic

Stacy Brethauer, MD
Bariatric and Metabolic Institute Cleveland Clinic

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

Address: Sangeeta Kashyap, MD, Department of Endocrinology, F20, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195; e-mail: kashyas@ccf.org; Philip Schauer, MD, Bariatric and Metabolic Institute, M61, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195; schauep@ccf.org

Dr. Brethauer has received research support from Bard-Davol, honoraria from Coviden for teaching and speaking, and honoraria and fees from Ethicon Endosurgery for consulting and serving on advisory committees or review panels.

Dr. Schauer has received honoraria, fees, or grants from Allergan, Bard-Davol, Barosense, Baxter, Cardinal/Snowden Pincer, Coviden, Ethicon Endosurgery, Gore, Surgical Excellence LLC, and Surgiquest for various work.

ABSTRACTObesity is a potent risk factor for the development and progression of type 2 diabetes, and weight loss is a key component of diabetes management. Bariatric surgery results in significant weight loss and remission of diabetes in most patients. After surgery, glycemic control is restored by a combination of enforced caloric restriction, enhanced insulin sensitivity, and increased insulin secretion.

KEY POINTS

  • After Roux-en-Y gastric bypass and biliopancreatic diversion, normoglycemia is restored within days, even before the patient has lost much weight.
  • Alterations in postprandial levels of intestine-derived hormones (glucagon-like peptide 1, peptide YY, and ghrelin) contribute to the robust metabolic benefits of intestinal bypass procedures.
  • Nutritional deficiencies are common after bariatric surgery, and long-term follow-up is mandatory for surveillance of metabolic status.
  • Although curing diabetes cannot yet be considered a goal of bariatric surgery, it may be a serendipitous benefit.

RISKS OF BARIATRIC SURGERY

Short-term risks

An important concern about using bariatric surgery to treat type 2 diabetes is the risk of morbidity and death associated with these procedures.

Buchwald et al13 performed a meta-analysis of 136 bariatric studies that included 22,094 patients. The 30-day operative death rates were 1.1% with biliopancreatic diversion, 0.5% with Roux-en-Y surgery, and 0.1% with restrictive procedures.

Laparoscopic adjustable gastric banding is considered the safest of the current bariatric procedures. It does not involve bowel anastomosis, and the risks of major hemorrhage, gastric perforation, and pulmonary embolism are less than 1%. Late complications requiring reoperation include band slippage or prolapse (5%–10%) and band erosion (1%–3%). The entire intestinal tract is left intact, so subsequent nutritional deficiencies are rare.43

Roux-en-Y gastric bypass carries an overall risk of major complications of 10% to 15%. Anastomotic leak (1%–5%), pulmonary embolism (< 1%), and hemorrhage (1%–4%) can be life-threatening but are rare if the staff are experienced. Late complications such as ulcer or stricture formation at the gastrojejunostomy site occur in 5% to 10% of cases and are managed nonoperatively.

Nutritional deficiencies

Nutritional deficiencies, including proteincalorie malnutrition and deficiencies of iron, other minerals, and vitamins A, E, D, and B12, occur in 30% to 70% of patients (Table 3). Patients at high risk of developing severe nutritional deficiencies include those who have lost more than 10% of their body weight by 1 month, those with anastomotic stenosis, those undergoing surgical revision, and those with persistent vomiting.44

Protein-calorie malnutrition is recognized by signs such as edema, hypoalbuminemia, anemia, and hair loss. To minimize this problem after Roux-en-Y surgery, we suggest that patients take in 60 to 80 g of protein and 700 to 800 kcal a day.

Vitamin deficiencies can lead to Wernicke encephalopathy (due to thiamine deficiency), peripheral neuropathy (due to vitamin B12 deficiency),45,46 and metabolic bone disease (due to long-term deficiencies of vitamin D and calcium). Often, vitamin deficiencies are present before surgery and require prompt supplementation to avoid exacerbation of these deficiencies afterward.

Biliopancreatic diversion procedures are performed at relatively few centers worldwide, largely because of the massive amounts of protein, fat, and carbohydrate malabsorption they cause. Long-term deficiencies of fat-soluble vitamins, iron, calcium, and vitamins B12 and D have been reported in one-third to one-half of patients undergoing these procedures, and nutritional supplementation is mandatory.43 Protein-calorie malnutrition occurs in 7% of cases, and 2% of patients require operative revision to lengthen the common channel.

Monitoring of nutrient and vitamin levels after bariatric surgery is recommended at least every 6 months. Table 3 summarizes the nutrient deficiencies to expect after Roux-en-Y surgery; Table 4 lists replacement strategies.

In rare cases, severe hypoglycemia has been noted after Roux-en-Y surgery and is associated with prandial hyperinsulinemia related to elevated GLP-1 levels.36,47 Neuroglycopenia and seizures have been reported in severe cases. Initial treatment of hypoglycemia involves dietary modification targeting carbohydrate restriction, the use of alpha glucosidase inhibitors such as acarbose (Precose), and referral to an endocrinologist for further management.

Long-term death rates

Death rates after bariatric surgery must be weighed against the long-term cardiovascular risks of continued obesity and type 2 diabetes.

Strong evidence now exists that bariatric surgery increases life expectancy48 and that this is largely attributable to reduction in cardiovascular risk factors such as diabetes and cancer. Recent studies have found that the long-term death rate is 32% to 73% lower for patients undergoing bariatric surgery than in matched controls who do not undergo surgery.49 A decrease in the death rate related to diabetes has played an important role in these results.
 

Acknowledgments: We acknowledge support from the National Institutes of Health, Multidisciplinary Clinical Research Career Development Programs Grant 5K12RR023264 (SRK), National Center for Research Resources, CTSA 1UL1RR024989, and research grants from Ethicon Endo-Surgery (PS,SRK).

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