Bariatric surgery for the prevention and treatment of type 2 diabetes

It is estimated that 80%–90% of people with type 2 diabetes are overweight (body mass index [BMI] 25.0–29.9) or obese (BMI ≥ 30.0).(1) A loss of 5%–10% of initial body weight has been shown to improve insulin sensitivity, glycemic control and blood pressure.(2) Weight loss via bariatric surgery can be recommended as a therapeutic intervention for certain people with type 2 diabetes, leading to sustained weight loss, as well as improvements in or remission of type 2 diabetes.(3-5) In fact, research by Diabetes Canada indicates that enhanced funding for bariatric surgery and greater uptake among eligible people would ultimately reduce the prevalence and burden of type 2 diabetes in Canada.(6) Although bariatric surgery is becoming more common, current demand for this surgery is not being met. Rising rates of obesity is one reason for this, as are barriers to accessing this surgery. These barriers include variations in access to procedures, patient selection criteria and funding, and gaps in knowledge and attitudes about the merits of bariatric surgery among patients, health providers and policy makers. All of these factors contribute to considerable wait times for surgery, which range from two to 15 years depending on the province.(7) Which patients are likely candidates for bariatric surgery? Diabetes Canada guidelines recommend that bariatric surgery be considered for select adults with type 2 diabetes and obesity with BMI ≥ 35.0, when healthy behaviour interventions with or without weight management medication(s) are inadequate in achieving target glycemic control or healthy weight goals.(8) What types of bariatric surgery are available in Canada? Bariatric surgery leads to weight loss by either decreasing the absorptive capacity of the gastrointestinal tract (malabsorptive surgery) or by limiting food intake (restrictive surgery), or a combination of both. Procedures performed include the following: Roux-en-Y gastric bypass involves creating a small gastric pouch (restricting food intake) connected to a roux limb (typically between 75–150 cm) which bypasses a large portion of the small intestine (preventing the absorption of nutrients). Sleeve gastrectomy is the surgical removal of the larger portion of the stomach, with suturing or stapling of the open edges to permanently reduce the stomach size. Adjustable gastric banding involves placing a silicone band around the upper part of the stomach laparoscopically to decrease the stomach size and reduce food intake. Biliopancreatic diversion is a very complex operation that principally includes removing a large portion of stomach to promote smaller meal sizes, and rerouting nutrients and digestive enzymes away from much of the small intestine in order to promote malabsorption. This procedure is most commonly used for patients who have a BMI > 50 (super-obese). Gastric banding has a lower likelihood of improving control or inducing remission in type 2 diabetes compared to the other procedures. It also has a higher rate of surgical complications, often leading to band removal; therefore, its use has largely been abandoned in North America.(9-12) What about complications? Post-surgery considerations and adverse events: Usually after discharge, patients follow a liquid diet, often with a caloric intake of 400–800 kcal daily. Due to reduced absorption of essential nutrients, multivitamins are usually recommended. Epigastric pain and vomiting may follow food intake so it is important to advise patients to eat slowly and to stop eating as soon as they reach satiety. For the first four to six months, during the time of rapid weight loss, body weight and blood pressure monitoring is recommended weekly. Blood glucose levels should also be measured daily. Both antihypertensive and antihyperglycemic medications may require frequent adjustments during this period. Other medications may also require dose adjustments since their uptake and metabolism may be altered; this is particularly important for medications with a narrow therapeutic index.(13) Currently, the risk of short- and long-term major adverse events, including additional operations, interventions and hospitalizations, is higher following gastric bypass than sleeve gastrectomy; however, more long-term randomized and observational studies are needed to confirm these findings beyond a five-year follow-up.(14) Weight gain: Most patients can expect to regain some weight over time, usually starting in the second year postoperatively, but full weight regain is relatively rare.(14) Diabetes recurrence: People who experience remission of type 2 diabetes with bariatric surgery may experience recurrence of diabetes years later; thus, life-long monitoring and screening for recurrence is important.(15) How can you help your patients who may be eligible for bariatric surgery? It can be a daunting experience for someone to navigate the process for accessing weight-loss surgery. Potential candidates should be encouraged to engage in a shared decision-making conversation about the risks and benefits of surgery compared with continuing usual medical and lifestyle treatment. This conversation should involve an interprofessional team with medical, surgical, psychiatric and nutritional expertise to determine if the person is a good candidate for surgery. Financial barriers may not allow for certain types of surgery depending on provincial coverage. Given the potential for long wait times, the conversation should be started early! Shelley Diamond, BScPhm, is a pharmacist and co-founder of www.diabetescarecommunity.ca, an extensive online resource for Canadians living with diabetes, their families and healthcare professionals. References 1. Wing RR. Weight loss in the management of type 2 diabetes. In: Gerstein HC, Huanes B, eds. Evidenced-based diabetes care. Hamilton: B.C. Decker Inc. 2000; 252-76. 2. Goldstein DJ. Beneficial effects of modest weight loss. Int J Obes Relat Metab Disord 1992;16:397-415. 3. Mingrone G, Panunzi S, De Gaetano A, et al. Bariatric surgery versus conventional medical therapy for type 2 diabetes. N Engl J Med 2012;366:1577-85. 4. Ikramuddin S, Billington CJ, Lee WJ, et al. Roux-en-Y gastric bypass for diabetes (the Diabetes Surgery Study): 2-year outcomes of a 5-year, randomised, controlled trial. Lancet Diabetes Endocrinol 2015;3:413-22. 5. Schauer PR, Bhatt DL, Kirwan JP, et al. Bariatric surgery versus intensive medical therapy for diabetes - 5-year outcomes. N Engl J Med 2017;376:641-51. 6. Diabetes Canada. Bariatric surgery as a type 2 diabetes intervention strategy. https://www.diabetes.ca/advocacy---policies/advocacy-reports/bariatric-surgery-as-a-type-2-diabetes-intervention-strategy (accessed August 25, 2021). 7. Coburn C. Weight loss surgery Canada – wait times, insurance & surgeon list. May 21, 2021. https://www.bariatric-surgery-source.com/bariatric-surgery-canada.html (accessed August 10, 2021). 8. Wharton S, Pedersen S, Lau D, et al. Weight management in diabetes (Chapter 17). Diabetes Canada Clinical Practice Guidelines Expert Committee. Diabetes Canada 2018 clinical practice guidelines for the prevention and management of diabetes in Canada. Can J Diabetes 2018;42:S124-9. 9. Courcoulas AP, Goodpaster BH, Eagleton JK, et al. Surgical vs medical treatments for type 2 diabetes mellitus: a randomized clinical trial. JAMA Surg 2014;149:707-15. 10. Puzziferri N, Roshek TB 3rd, Mayo HG, et al. Long-term follow-up after bariatric surgery: a systematic review. JAMA 2014;312:934-42. 11. Mingrone G, Panunzi S, De Gaetano A, et al. Bariatric-metabolic surgery versus conventional medical treatment in obese patients with type 2 diabetes: 5 year follow-up of an open-label, single-centre, randomised controlled trial. Lancet 2015;386:964-73. 12. Khorgami Z, Shoar S, Andalib A, et al. Trends in utilization of bariatric surgery, 2010–2014: Sleeve gastrectomy dominates. Surg Obes Relat Dis 2017;13:774–8. 13. Bjørklund G, Semenova Y, Pivina L, et al. Follow-up after bariatric surgery: a review. Nutrition 2020;78:110831. doi: 10.1016/j.nut.2020.110831. 14. Arterburn DE, Telem DA, Kushner RF, et al. Benefits and risks of bariatric surgery in adults: a review. JAMA 2020;324:879-87. 15. Sjöström L, Peltonen M, Jacobson P, et al. Association of bariatric surgery with long-term remission of type 2 diabetes and with microvascular and macrovascular complications. JAMA 2014;311:2297-304.