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Diabetes and Weight Loss Surgery
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The obesity epidemic in the United States is paralleled by an equally serious diabetes epidemic. In 1994, most states had < 18% obesity prevalence and < 6% diabetes prevalence. By 2009, consistent increases resulted in all states having obesity prevalence > 18% with prevalence exceeding 26% in 30 states. Similarly, diabetes prevalence increased to exceed 9% in 15 states by 2009, with only 2 states having a prevalence < 6%.1 This is particularly apparent in the southern and Appalachian states, which have the highest prevalence of both conditions. In fact, the prevalence of diabetes is 11% or greater in 15 mostly southern states.2 Diabetes affects 25.8 million people in the United States, which is equal to 8.3% of the US population.3 An additional 79 million people have prediabetes. At least one estimate predicts that by 2020, one-half of the US population will have diabetes or prediabetes.4
After adjusting for age, sex, smoking status, and body mass index (BMI), diabetes is a significant risk factor for premature death from several causes.5 Weight loss can provide a survival benefit to overweight people with diabetes. This is supported by data from a prospective 10-year mortality study that, after covariate adjustment, found that patients with intentional weight loss had a 25% decrease in all-cause mortality, and a 28% reduction in deaths from cardiovascular diseases and diabetes, compared with patients who had no weight change during that interval.6
The close association between diabetes and obesity and benefits of bariatric surgery in these patients has been explored in several studies. As a result, the International Diabetes Foundation published a position statement that includes bariatric surgery in an algorithm for treating obese patients with type 2 diabetes.7 The algorithm recommends surgery be considered early in the management process if BMI is gt; 35 kg/m2. The remission of diabetes after bariatric surgery has also been the subject of many investigations (Table). The effects of surgery seem to be immediate; in fact, fasting plasma glucose may normalize before hospital discharge, particularly after bypass surgery. Although the mechanism is not completely understood, theories include that the effect is incretin-related, or that it may be due to nutrients entering the distal gastrointestinal tract sooner than occurs after other surgeries. Gastric restrictive operations such as banding appear to improve type 2 diabetes primarily through weight loss, although the mechanism may be more complex.
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After Roux-en-Y gastric bypass (RYGB), biliopancreatic diversion (BPD), or BPD/duodenal switch (DS), patients who require insulin have a decreased requirement in the early postoperative period. Most of these patients can discontinue insulin by 6 weeks after surgery, and some stop insulin treatment before discharge. Patients must be diligent in glucose monitoring to avoid hypoglycemia, particularly in the postoperative period. During the perioperative period, the institutional intensive insulin therapy protocol should be followed. If the patient is not in the intensive care unit, subcutaneous insulin can be used, preferably basal and rapid-acting insulin analogs rather than NPH and regular insulins.
Long-term effects on diabetes after bypass surgery include weight loss-dependent and weight loss-independent effects. Bypass of the proximal small bowel can result in an increase in glucagon-like peptide-1 (GLP-1) and hyperinsulinemia. Early presentation of undigested food to the distal small bowel produces a trend toward higher GLP-1 levels and improvement in glucose-stimulated insulin secretion. These and other intestinal factors may also restore meal-induced suppression of ghrelin release.
Glycemic Goals and Strategies
Perioperative management of diabetes is facilitated if glycemic control is achieved preoperatively. Adequate glycemic control also affects complications, particularly surgical infections.
Sulfonylureas and other secretagogues, including the meglitinides (repaglinide and nateglinide), should be discontinued prior to surgery. During the immediate postoperative period insulin sensitivity may improve, and these drugs would increase the risk of hypoglycemia. Sulfonylureas should be reintroduced later only if clinically indicated. Adequate follow-up is necessary to ensure that proper treatment is provided.
Long-term management of patients who achieve remission of type 2 diabetes after surgery is not clearly defined. However, routine follow-up should be continued. Hypoglycemia can occur because of the reduced insulin requirement. Post-RYGB patients who present with postprandial symptoms of hypoglycemia, particularly neuroglycopenic symptoms, should undergo further evaluation for the possibility of insulin-mediated hypoglycemia. Postprandial hypoglycemia after gastric banding is due to a combination of gastric dumping and inappropriately increased insulin secretion, either as a failure to adaptively decrease insulin secretion after gastric bypass surgery.
The use of surgical intervention as treatment for diabetes and metabolic disease has shown promise, but additional investigations are required. There is a potential for occurrence of nesidioblastosis (β-cell hyperplasia) after gastric bypass, but it is very rare and is related to diet, which can be controlled. The scientific rationale for surgical diabetes control is sound. However, long-term outcome data on the general impact of surgery on overall morbidity and mortality are needed. The long-term benefits, cost-effectiveness, and risks of bariatric surgery should be compared with optimal lifestyle and pharmacotherapy interventions and in well-designed prospective trials. Several observational and randomized controlled trials are ongoing, which are enrolling patients with diabetes who in some studies may have a BMI as low as 27 kg/m2, and with follow-up intervals of up to 10 years.8 These studies are expected to provide valuable data that can contribute to the development of management strategies for persons with diabetes who undergo bariatric surgery.
Discussion
What is the prevalence of diabetes in bariatric surgery patients?
John Morton, MD, MPH, FACS: Approximately 30% of bariatric surgery patients have diabetes.9 Patients with prediabetes are more prevalent.
Is the postoperative diabetes remission rate related to how long the patient has had diabetes?
Morton: Yes, it is. The challenge to the pancreas is greater in older patients and in those who have had diabetes for more than 5 years. Although diabetes improves for most patients, it is important to consider these issues when counseling patients.
Do other organizations such as the American Diabetes Association (ADA) and American College of Endocrinology (ACE) recommend bariatric surgery as part of diabetes management in their guidelines?
Lawrence Blonde, MD, FACP, FACE: The ADA published updated standards of medical
care in diabetes for 2011, which state that bariatric surgery may be considered for adults with type 2 diabetes whose BMI is > 35 kg/m2. They emphasize the need for life-long support and monitoring.10 An algorithm published in 2009 by a writing group assembled by the ADA and the EASD is scheduled for an update; the extant version does not include surgery;11 similarly, the algorithm produced in 2009 by a writing group assembled by AACE/ACE does not include bariatric surgery.12 When the guidelines and algorithms adopt a more personalized view, acknowledging that treatment must be individualized for each patient, surgery may be included.
References
1. Centers for Disease Control and Prevention. Maps of diabetes and obesity in 1994, 2000, and 2009. September 2010. http://www.cdc.gov/diabetes/statistics/slides/maps_diabetesobesity94.pdf. Accessed November 8, 2011.
2. Barker LE, Kirtland KA, Gregg EW, Geiss LS, Thompson TJ. Geographic distribution of diagnosed diabetes in the U.S.: A diabetes belt. Am J Prev Med. 2011;40(4):434-439.
3. Centers for Disease Control and Prevention. National diabetes fact sheet, 2011. http://www.cdc.gov/diabetes/pubs/pdf/ndfs_2011.pdf. Accessed June 1, 2011.
4. United Health. The United States of Diabetes: Challenges and opportunities in the decades ahead. November 2010. http://www.unitedhealthgroup.com/hrm/UNH_WorkingPaper5.pdf. Accessed June 1, 2011.
5. Emerging Risk Factors Collaboration, Seshasai SR, Kaptoge S, et al. Diabetes mellitus, fasting glucose, and risk of cause-specific death. N Engl J Med. 2011;364(9):829-841.
6. Williamson DF, Thompson TJ, Thun M, Flanders D, Pamuk E, Byers T. Intentional weight loss and mortality among overweight individuals with diabetes. Diabetes Care. 2000;23(10):1499-1504.
7. International Diabetes Foundation. Position Statement. Bariatric surgical and procedural interventions in the treatment of obese patients with type 2 diabetes. http://www.idf.org/webdata/Bariatric-Surgery-Press-Briefing.pdf. Accessed June 1, 2011.
8. National Library of Medicine. Basic Search. http://ClinicalTrials.gov. Accessed June 1, 2011.
9. Pinkney J, Kerrigan D. Current status of bariatric surgery in the treatment of type 2 diabetes. Obesity Reviews. 2004;5(1):69-78.
10. American Diabetes Association. Standards of medical care in diabetes — 2011. Diabetes Care. 2011;34(suppl 1):S11-S61.
11. Nathan DM, Buse JB, Davidson MB, et al; American Diabetes Association; European Association for the Study of Diabetes. Medical management of hyperglycaemia in type 2 diabetes mellitus: A consensus algorithm for the initiation and adjustment of therapy: A consensus statement from the American Diabetes Association and the European Association for the Study of Diabetes. Diabetologia. 2009;52(1):17-30.
12. Rodbard HW, Jellinger PS, Davidson JA, et al. Statement by an American Association of Clinical Endocrinologists/American College of Endocrinology consensus panel on type 2 diabetes mellitus: An algorithm for glycemic control. Endocr Pract. 2009;15(6):540-559.