Bariatric Times

FEB 2018

A peer-reviewed, evidence-based journal that promotes clinical development and metabolic insights in total bariatric patient care for the healthcare professional

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Review 15 Bariatric Times • February 2018 achieved after RYGB might upregulate the metabolic activity of residual brown adipose tissue located in small amounts in the supraclavicular fat depots of adults, and even induce browning of white adipose tissue, leading to a better metabolic state and facilitating weight loss. 16 CLINICAL AND BIOLOGICAL DETERMINANTS OF WEIGHT LOSS AND T2DM REMISSION AFTER BARIATRIC SURGERY With regard to weight loss, the preoperative postprandial gut hormone responses (incretin effect) are not prognostic for surgically induced weight loss. 14 Interestingly, higher baseline levels of the soluble receptor for advanced glycation endproducts (sRAGE) have been associated with better weight loss after bariatric surgery (RYGB, SG, LAGB). 24 A large number of studies have tried to explore the best biological and clinical predictors of T2DM remission after bariatric surgery. In this context, the distinction among remitters, nonremitters, and relapsers after initial remission is crucial. T2DM remission should be defined accurately and uniformly to facilitate comparability of results between different studies. Complete T2DM remission is defined as fasting plasma glucose less than 100mg/dL and/or HbA1c less than six percent for at least one year after surgery in the absence of glucose-lowering pharmacologic treatment. Partial T2DM remission is defined as fasting plasma glucose less than 126mg/dL and/or HbA1c less than 6.5 percent and off antidiabetic medication for at least one year. 15,25 A prolonged complete T2DM remission, extending beyond five years, might be viewed as operationally equivalent to cure. 25 A cautious approach is, however, warranted when using these terms, especially when proposing monitoring and treatment algorithms for T2DM. Based on data from long-term trials, the median T2DM-free interval after surgery has been estimated to be 8.3 years (RYGB), while T2DM relapse— restarting antidiabetic medication or fasting plasma glucose less than 126mg/dL and/or HbA1c greater than 6.5percent—might be observed in as many as 20 to 30 percent of patients after initial remission over a period of six years. 26 Data from a retrospective cohort study in a large number of patients with T2DM undergoing RYGB, show that up to 70 percent of the patients might experience an initial complete remission in the first five years, but among these, 35 percent might redevelop T2DM within five years after remission. 26 The favorable effect of surgically induced weight loss on T2DM remission appears to be independent of initial BMI. Accumulating evidence suggests that preoperative BMI within the obese range is not able to reliably predict cardiometabolic benefits with regard to T2DM prevention and remission, incidence, and mortality of cardiovascular disease. 15 A recently published meta-analysis of RCTs, controlled clinical trials, and cohort studies conducted in two distinct BMI groups (<35 and >35 kg/m 2 ), revealed similar T2DM remission rates in both groups, regardless of baseline BMI. 27 Whereas preoperative BMI appears to be unhelpful as a determinant of metabolic improvement, body weight change trajectories, namely the degree of weight reduction, play a central role in predicting responders vs. nonresponders. 26 In patients experiencing massive weight loss after surgery, T2DM remission rates are considerably higher compared to subjects with less profound weight loss, irrespective of baseline BMI categorization, 26 suggesting that weight loss, per se, appears to have a dominant effect. The International Diabetes Federation's definition of optimal metabolic control might be more helpful, as the focus shifts from remission to long-term control of all metabolic parameters. As such, the benefits of metabolic surgery with regard to glycemia, hypertension, and dyslipidemia are equally valued. The complementary use of medication is also encouraged to enhance and maintain the metabolic benefits of surgery longer. Beyond weight reduction, baseline T2DM duration, preoperative use of intensive insulin regimens, and poorer glycemic control have been consistently associated with lower rates of T2DM remission and higher risk of relapse. 27,28 Many researchers, however, argue that these are the patients that would actually benefit most from metabolic surgery because they can have the largest improvements in metabolic control even if they do not achieve complete hyperglycemia remission. These patients might need to be prioritized over those who can easily be placed into remission, as the former typically have the highest morbidity and mortality. On the contrary, a shorter T2DM duration (<8 years), lower preoperative fasting glycemia, and surgical procedures involving intestinal diversion instead of gastric only procedures might independently predict higher T2DM remission rates and lower risk of recidivism. 27 Lower baseline waist circumference might further predict a greater HbA1c reduction, 27 whereas baseline visceral fat area is also associated with better metabolic outcomes, especially in Asian patients with T2DM and increased visceral fat, despite only mildly elevated BMI. 29 Thus, it becomes evident that an early weight- loss operation combined with better controlled baseline glycemia are expected to be beneficial, prompting a need for the early recognition of appropriate candidates for bariatric surgery, 27,28 but this should not be done at the expense of patients with long-standing and poorly controlled diabetes, in whom a surgical intervention would likely have dramatic and long-term beneficial effects on glycemia, even if complete remission is not achieved. SHORT- AND MID-TERM OUTCOMES OF BARIATRIC SURGERY IN PATIENTS WITH OBESITY AND T2DM Table 1 summarizes the key findings of major RCTs studying the short- and mid-term (up to 1 and 3 years, respectively) outcomes of bariatric surgery in patients with overweight or patients with obesity and T2DM regarding weight loss, T2DM remission, improvement of TABLE 1. Short and mid-term outcomes of bariatric surgery in patients with T2DM REFERENCE STUDY POPULATION INTERVENTION DURATION OF FOLLOW-UP MAJOR OUTCOMES KEY RESULTS Dixon et al, 2008 30 N=60, BMI 30–40, recently diagnosed T2DM LAGB 2 years Weight loss, T2DM remission Increased weight loss and T2DM remission after surgery vs. conventional diabetes treatment Mingrone et al, 2012 6 N=60, BMI >35, inadequately controlled T2DM for at least 5 years RYGB, BPD 2 years HbA1c Increased TD2M remission after surgery vs. conventional treatment Schauer et al, 2012 7 N=150, poorly controlled T2DM RYGB, SG 1 year Weight loss, HbA1c Weight loss: RYGB > SG > IMT, decreased medication to lower glucose, lipids, and blood pressure after surgery vs. IMT Ikramuddin et al, 2013 11 N=120, BMI 30–40, poorly controlled T2DM RYGB 1 year CVD risk factors Better control of HbA1c, lipids, and blood pressure after surgery vs. IMT Courcoulas et al, 2014 14 N=69, obesity grade I/II RYGB, LAGB 1 year Weight loss, T2DM remission Weight loss: RYGB > LAGB > LWLI, increased T2DM remission vs. LWLI Halperin et al, 2014 10 N=38, BMI 30–42, T2DM of at least 1 year RYGB 1 year Partial T2DM remission, CVD risk factors Increased T2DM remission and greater improvement in blood pressure and lipids vs. IMT, equal improvement in QOL Parikh et al, 2014 24 N=57, BMI 30–35, T2DM RYGB, SG, LAGB 6 months T2DM remission, insulin resistance, medication use Increased T2DM remission, improved HOMA-IR, decreased HbA1c, fasting glucose and antidiabetic drugs after surgery vs. MWM Schauer et al, 2014 33 N=150, poorly controlled T2DM RYGB, SG 3 years T2DM remission, QOL, medication use Increased T2DM remission, decreased glucose-lowering medication, increased QOL after surgery vs. IMT Wentworth et al, 2014 31 N=51, BMI 25–30, T2DM LAGB 2 years T2DM remission Increased T2DM remission after LAGB vs. conventional treatment alone, acceptable adverse event profile Coucoulas et al, 2015 13 N=69, obesity grade I/II RYGB, LAGB 3 years Weight loss, T2DM remission Weight loss RYGB > LAGB > LWLI, increased T2DM remission vs. LWLI Ding et al, 2015 32 N=45, BMI 30–45, T2DM of at least 1 year LAGB 1 year Glycemic endpoint comprising HbA1c and fasting glucose Similar HbA1c reduction, weight loss at three months, blood pressure, lipids, and CVD risk scores after LAGB and MWM (no difference) Cummings et al, 2016 9 N=43, BMI 30–45, T2DM RYGB 1 year Complete T2DM remission, medication use Increased T2DM remission, decreased antidiabetic drugs after surgery vs. IMT BMI: body mass index; BPD: biliopancreatic diversion; CVD: cardiovascular disease; HbA1c: glycosylated haemoglobin; HOMA-IR: homeostasis model assessment index for insulin resistance; IMT: intensive medical treatment; LAGB: laparoscopic adjustable gastric banding; LWLI: lifestyle weight loss intervention; MWM: medical weight management; QOL: quality of life; RYGB: Roux-en-Y gastric bypass; SG: sleeve gastrectomy; T2DM: type 2 diabetes mellitus

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