Medical vs Surgical Treatment of Obesity in Diabetes

Educational Objectives

The goals of this program are to compare medical management with bariatric surgery for weight loss and prevention of type 2 diabetes. After hearing and assimilating this program, the clinician will better be able to:

1. Compare medical and surgical approaches to the management of obesity and evaluate their outcomes in patients with diabetes.

2. Identify preoperative factors that predict long-term remission of diabetes after bariatric surgery.

Summary

Treatment of obesity: Prevention, treatment, and reversal of associated complications are the primary goals. In the Diabetes Prevention Program (DPP), a weight loss of 7% was associated with a 57% reduction in the incidence of diabetes. Research has shown that combination of lifestyle modification and medication yields ≤15% weight loss. The American Heart Association, American College of Cardiology, and Obesity Society recommend weight-loss therapy in patients with body mass index (BMI) >30 or >25 with at least one obesity-related comorbidity.

Nonsurgical Approaches

Diet: Dietary adherence is the greatest predictor of weight loss, which requires reduction of energy intake below energy expenditure while accommodating individual preferences. Very-low-calorie diets (<800 kcal/day) do not yield a greater long-term benefit than diets with >800 kcal/day. Calorie counting and frequent weigh-ins facilitate long-term weight loss; skipping breakfast has little effect.

Exercise: Although exercise is less effective than calorie restriction, it helps maintain weight loss and improve blood pressure and lipid profiles, thereby reducing cardiovascular risks.

Medications: Agents approved for long-term use include orlistat, lorcaserin, phentermine-topiramate, naltrexone-bupropion, and liraglutide. Most agents approved for short-term use (<12 weeks; eg, phentermine) are appetite suppressants.

Surgical Approaches

Access: Bariatric surgery is not accessible to all individuals, partially because of the high prevalence of obesity (≈117 million individuals in the United States). In 2015, 196,000 bariatric surgeries were performed. Furthermore, many patients are unable to afford bariatric surgery, and many do not have access to a skilled surgeon.

Medical vs surgical treatment: A systematic review of meta-analyses of randomized controlled trials showed that surgery yielded favorable outcomes in patients with either nonsevere or severe obesity, and all bariatric procedures (eg, sleeve gastrectomy, gastric bypass, gastric banding, and biliopancreatic diversion) yielded more weight loss than did medical management. The authors of the review concluded that bariatric surgery is a better therapeutic option for weight loss irrespective of duration of follow-up, type of surgery, or level of obesity.

Another review, of 11 randomized controlled trials, showed that surgery was superior for the treatment and resolution of comorbidities associated with obesity, including greater body weight, type 2 diabetes, high-density lipoprotein (HDL) cholesterol levels, and metabolic syndrome.

However, access to bariatric surgery is poor, and bariatric surgery is not a mandated benefit in all states. Approximately 1% of patients who could benefit receive bariatric surgery.

Management of diabetes: Approximately 80% of patients with diabetes are obese. The relationship between obesity and diabetes is complex, and the mechanism by which obesity causes diabetes and how the duration of type 2 diabetes affects the benefits of weight loss are unclear.

Prevention of Diabetes in Obese Individuals

Diabetes Prevention Program (DPP): The program randomized 3200 obese individuals (age 25-85 years) at high risk for diabetes to receive a lifestyle intervention (with a goal of 7% weight loss), metformin, or placebo (diet and exercise information that was provided to all participants). The lifestyle intervention decreased the incidence of diabetes by 58% and led to a mean weight loss of ≈15 lb at 1 year. Each kg of weight loss was associated with a 16% reduction in the incidence of diabetes.

The DPP Outcomes Study performed a follow-up analysis of 85% of the initial cohort. Over a cumulative 10-year follow-up, the lifestyle group had a 34% reduction in the incidence of diabetes, and the metformin group had an 18% reduction. The Centers for Disease Control and Prevention (CDC), in collaboration with nongovernment partners, developed an evidence-based curriculum that included training guides for lifestyle coaches, to help them deliver a 1-year program for lifestyle modification. In March 2016, the Centers for Medicare and Medicaid Services certified that the national DPP model was cost-saving and improved the quality of patient care.

A descriptive study of 14,000 adults enrolled in DPP programs from 2012 to 2016 showed that 35.5% achieved a 5% weight-loss goal and 41.8% met the goal for physical activity (150 minutes per week). For every additional exercise session attended and 30 minutes of activity reported, participants lost 0.3% body weight; however, only 43% of individuals completed all sessions.

MOVE weight management program: This translation of the DPP program for veterans included ≈238,000 participants between 2005 and 2012. Of these, ≈20,000 were considered intense and sustained participants, and they had a 33% reduction in incidence of diabetes. Individuals with lower levels of involvement had a 20% reduction. Incidence of diabetes was reduced irrespective of sex, race, or age.

Medications: Glucagon-like peptide-1 (GLP-1) receptor agonists (eg, liraglutide), metformin, and sodium-glucose cotransporter-2 (SGLT2) inhibitors have been associated with weight loss and cardiovascular benefits.

Outcomes of Bariatric Surgery

Bariatric surgery: Bariatric surgery has been shown to “cure” diabetes in the short term, but the rate of recurrence is high in long-term follow-up. Patients with a long duration of diabetes before surgery are less likely to achieve remission.

DiaRem score: The researchers who developed the score analyzed 259 preoperative clinical variables and showed that requirement for insulin was associated with lower likelihood of remission at 5 years after surgery. Younger age, lower hemoglobin A1c, and higher concentration of serum insulin were associated with greater likelihood of diabetes remission. External validation of the score from the Cleveland Clinic showed similar findings. However, long-term data (>5 years) is still needed to assess the benefits of bariatric surgery.

Early studies: A single-institution experience with patients who received gastric bypass surgery showed that insulin requirements and glucose levels decreased immediately after surgery. The participants had 50% weight loss from baseline to 14 years, and 83% of patients maintained normal levels of plasma glucose and A1C. Retrospective studies showed that diabetes is improved or cured after surgery and that many patients do not require as many antidiabetic drugs.

In 2010, the first Diabetes Surgery Summit consensus conference stated that bariatric surgery has a valuable role in treatment of type 2 diabetes in patients with severe obesity (BMI >35) or moderate obesity plus diabetes inadequately controlled by conventional therapies. However, they stated that randomized controlled trials are needed to validate the retrospective data.

STAMPEDE trial: This prospective single-center trial randomized patients to receive intensive medical therapy alone or intensive medical therapy plus sleeve gastrectomy or gastric bypass surgery. The primary endpoint (A1C <6%) was met in 12% of the medical group, 42% of the sleeve gastrectomy group, and 37% of the gastric bypass group. Polypharmacy and need for cardiovascular medications decreased with both types of surgery but not with medical management.

The 3-year follow-up data showed that bariatric surgery, but not medical management, significantly improved quality of life scores, A1C, and BMI. The 5-year follow-up data showed that the bariatric surgery reduced the need for diabetes medications, and a greater proportion of patients were able to eliminate all medications.

Metabolic Surgery in the Treatment Algorithm for Type 2 Diabetes: A Joint Statement by International Diabetes Organizations (2016): The second Diabetes Surgery Summit stated that there is sufficient evidence to support inclusion of metabolic surgery among antidiabetic interventions for individuals with type 2 diabetes and obesity, and metabolic surgery may be considered for all classes of obesity.

Inadequacy of long-term data: An article by Livingston argued that for studies of bariatric surgery to be considered adequate, they need to have >2 years of outcome data and follow-up measures on ≥80% of patients. However, only 16% of studies of bariatric surgery have had ≥2 years of follow-up data, and of these, only 29% had ≥80% follow-up.

Type of surgical procedure: Preoperative factors that predict outcomes include number of medications being taken by patient, use of insulin, duration of diabetes, and control of A1C. Data show that gastric bypass surgery yields slightly better outcomes than sleeve gastrectomy in patients with a low DiaRem score (ie, with a high likelihood of remission), although the operative risk is higher with gastric bypass surgery. Gastric bypass is recommended for patients with a moderate score because resolution of diabetes is better than with sleeve gastrectomy. Outcomes are similar with gastric bypass surgery and sleeve gastrectomy in patients with a high score, and for them sleeve gastrectomy is recommended because it is safer.

Reducing medications after surgery: Reducing doses of medications may be considered for diabetes and hypertension, but withdrawal of statins may not be advised because they may continue to be useful for reducing cardiovascular risk.

Complications after surgery: Patients may develop osteoporosis, although most studies of bone density are poor in quality because dual-energy X-ray absorptiometry tends to be inaccurate in obese individuals. Calcium malabsorption has been documented 3 months after surgery. Vitamin D deficiency is common, and patients may require high doses of vitamin D supplementation. Furthermore, hypoglycemia can be difficult to manage after bariatric surgery.

Weight regain: A study showed that approximately one-third of patients regained >5% of their initial weight loss ≤2 years after surgery. Many patients are lost to follow-up. A study from Stanford showed that patients who do not show up for their 12-month follow-up appointment tend to be younger and of nonwhite ethnicity. Patients who did not return for follow-up at 3 and 6 months had less weight loss and lower rates of remission from diabetes.

Readings

Diabetes Prevention Program Research Group: Long-term effects of lifestyle intervention or metformin on diabetes development and microvascular complications over 15-year follow-up: the Diabetes Prevention Program Outcomes Study. Lancet Diabetes Endocrinol. 2015 Nov;3(11):866-75; Knowler WC et al: Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med. 2002 Feb 7;346(6):393-403; Ribaric G et al: Diabetes and weight in comparative studies of bariatric surgery vs conventional medical therapy: a systematic review and meta-analysis. Obes Surg. 2014 Mar;24(3):437-55; Rubino F et al: The Diabetes Surgery Summit consensus conference: recommendations for the evaluation and use of gastrointestinal surgery to treat type 2 diabetes mellitus. Ann Surg. 2010 Mar;251(3):399-405; Rubino F et al: Metabolic Surgery in the Treatment Algorithm for Type 2 Diabetes: a joint statement by International Diabetes Organizations. Diabetes Care. 2016 Jun;39(6):861-77; Schauer PR et al: Bariatric surgery versus intensive medical therapy for diabetes: 3-year outcomes. N Engl J Med. 2014 May 22;370(21):2002-13; Schauer PR et al: Bariatric surgery versus intensive medical therapy for diabetes — 5-year outcomes. N Engl J Med. 2017 Feb 16;376(7):641-651; Zhou X et al: Effects of bariatric surgery on mortality, cardiovascular events, and cancer outcomes in obese patients: systematic review and meta-analysis. Obes Surg. 2016 Nov;26(11):2590-2601

Disclosures

Dr. Anderson reported relationships with Amylin Pharmaceuticals (G), Daichi Sankyo Company (B), Eli Lilly and Company (B), Novo Nordisk (B), and sanofi-aventis UC (A). Drs. Leib and Wolgemuth, and the members of the planning committee reported nothing to disclose.

A=Advisory panel B=Speakers bureau C=Consultant G=Grant or other research support

Acknowledgements

CME/CE INFO

Accreditation:

The Audio- Digest Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

The Audio- Digest Foundation designates this enduring material for a maximum of 0 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Audio Digest Foundation is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's (ANCC's) Commission on Accreditation. Audio Digest Foundation designates this activity for 0 CE contact hours.

Lecture ID:

DI081801

Expiration:

This CME course qualifies for AMA PRA Category 1 Credits™ for 3 years from the date of publication.

Instructions:

To earn CME/CE credit for this course, you must complete all the following components in the order recommended: (1) Review introductory course content, including Educational Objectives and Faculty/Planner Disclosures; (2) Listen to the audio program and review accompanying learning materials; (3) Complete posttest (only after completing Step 2) and earn a passing score of at least 80%. Taking the course Pretest and completing the Evaluation Survey are strongly recommended (but not mandatory) components of completing this CME/CE course.

Estimated time to complete this CME/CE course:

Approximately 2x the length of the recorded lecture to account for time spent studying accompanying learning materials and completing tests.