Bariatric surgery for diabetes requires lifelong nutrition follow-up

Issue: April 2019

BySusan Weiner, MS, RDN, CDN, CDCES, FADCES

In this issue, Susan Weiner, MS, RDN, CDE, CDN, FAADE, talks with nutritionist Lillian Craggs-Dino, DHA, RDN, LDN, CLT, who specializes in bariatric nutrition at Cleveland Clinic Foundation in Weston, Florida. She is co-author of the nutritional guidelines on micronutrients from the American Society for Metabolic and Bariatric Surgery.

How many bariatric and metabolic surgeries are performed in the United States, and who qualifies to get the surgery?

Craggs-Dino: According to the most recent data published by American Society for Metabolic and Bariatric Surgery (ASMBS), there were a total of 228,000 bariatric and metabolic procedures performed in the United States in 2017. Approximately 53.4% were vertical sleeve gastrectomy, and 17.8% were Roux-en-Y gastric bypass. This is a small number considering there are more than 93 million U.S. residents who live with obesity. The general qualifications for bariatric and metabolic surgery include having a BMI of at least 40 kg/m² or a BMI of at least 35 kg/m² with at least one weight-related comorbid condition, such as type 2 diabetes, hypertension, dyslipidemia or sleep apnea. Insurance providers may also impose preoperative medically supervised diets and other qualification criteria.

Is bariatric surgery considered a treatment option for diabetes?

Craggs-Dino: According to the Comprehensive Type 2 Diabetes Algorithim 2018 by the American Association of Clinical Endocrinologists and American College of Endocrinology, adults with obesity and comorbidities should be considered for bariatric surgery, especially if they are having trouble meeting therapeutic goals with treatment. A meta-analysis of 135 studies that included a total of 22,000 patients who had bariatric surgery showed that 86% of patients had either a dramatic improvement of type 2 diabetes or even a total remission. The STAMPEDE trial was a single-center, three-arm, randomized controlled study that compared three treatment programs: intensive medical nutrition therapy with no surgery, medical nutrition therapy and gastric bypass, or medical nutrition therapy and sleeve gastrectomy. Results at 12 months showed that 42% of the gastric bypass group reached an HbA1c less than 6%, as did 37% of the sleeve gastrectomy group and 12% of the medical nutrition therapy group. The most weight loss was seen with the group with gastric bypass, but the mechanism of diabetes remission with bariatric surgery appears to be influenced more by the metabolic effects of the surgery than the weight loss. Selecting which procedure, either the gastric bypass or the sleeve gastrectomy, to ameliorate obesity and diabetes, would be based on the patient’s BMI, medical history, health goals and a discussion with the surgeon and interdisciplinary team.

What are the current theories as to how the surgery treats diabetes?

Craggs-Dino: The exact mechanisms are still under investigation, but two widely debated hypotheses fall under either the “hindgut theory” or “foregut theory.” Both theories take a look at the role of hormonal and metabolic changes induced by the surgery. According to the hindgut theory, the rapid delivery of undigested food may enhance the release of insulin-stimulating hormones such as GLP-1. The foregut theory, on the other hand, holds that, particularly with Roux-en-Y gastric bypass, bypassing the upper or proximal small intestine may account for the antidiabetes effects. In both procedures, the hunger hormone ghrelin is decreased, and this causes the patient to feel less hungry. Together with caloric restriction, the patient is in a hypocaloric state, which may also contribute to antidiabetes effects.

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Are there any nutritional risks to these surgeries?

Craggs-Dino: Bariatric and metabolic surgery has been shown to be safer than many other surgeries, such as gallbladder, cardiac and spine surgery, but because of the nature of bariatric surgery, certain nutritional guidelines must be followed. Bariatric and metabolic surgery is not “the easy way out” to lose weight, nor is it a “magic bullet.” Patients must understand that the surgery is just one component of a healthy lifestyle that one must adopt to have long-term success. Patients with these surgeries are shown to have a higher risk for vitamin and mineral deficiencies, especially vitamins B12, B1, folic acid, vitamin D, iron and calcium. In the long term, these deficiencies can cause anemia, metabolic bone disease and peripheral neuropathy. Those with gastric bypass may have a slightly higher risk due to the malabsorptive properties of the surgery; however, even the sleeve gastrectomy may pose risk, especially with vitamin B12. Lifelong vitamin and mineral supplementation is recommended as is lifelong follow-up, including annual lab work to monitor nutrition status. Protein and fluid intake are also paramount to reduce risk for dehydration and loss of lean body mass. Successful food tolerance is also enhanced by teaching the patient proper eating mechanics and appropriate food choices and textures.

What is your advice to patients and clinicians should they be interested in bariatric and metabolic surgery?

Craggs-Dino: The decision to undergo bariatric and metabolic surgery is a personal decision, but one that is best decided with support from the patient’s family and medical team. A clinician should refer an appropriate and interested patient to a highly reputable bariatric and metabolic institute that offers an interdisciplinary team of physicians, surgeons, nurses, dietitians and psychologists as their core team. Patient education, support and follow-up should be an ongoing process. A patient-centered approach to care is critical. Pros and cons, risks and benefits, and goal setting should be an integral part of the conversation.