Metabolic Bariatric Surgery Research Articles

Surgery as pluripotent instrument for metabolic disease. What are the mechanisms?

Bariatric metabolic surgery currently offers the most effective treatment to achieve sustained weight loss and improvement in metabolic comorbidities, such as type 2 diabetes, hypertension, dyslipidemia and cardiovascular diseases. The number of cases performed in Germany and also worldwide is continuously increasing but the underlying mechanisms of bariatric metabolic surgery are still not completely elucidated. Roux-en-Y gastric bypass (RYGB) surgery represents one of the most commonly used and therefore most frequently investigated bariatric metabolic procedures. Traditionally, its effectiveness was attributed to food restriction and malabsorption but in the meantime it has become evident that the underlying postoperative mechanisms of RYGB seem to be much more complex. Potential mechanisms include multiple physiological changes, such as altered levels of gastrointestinal hormones, increased energy expenditure and modified gut microbiota as well as many other factors. This review article therefore aims to offer an up to date overview of relevant mechanisms that improve obesity and its associated comorbidities after RYGB surgery.

Diabetes mellitus tipo 2 y obesidad: ¿tratar la obesidad o la diabetes?

In this article, we review the results that can be expected after significant weight loss in patients with type 2 diabetes mellitus. We provide consensus-based documentation supported by the American Diabetes Association, the European Association for the Study of Diabetes, and the International Diabetes Federation on the importance of physical exercise, metabolic-bariatric surgery, and drug therapy. Lastly, we report the results of studies published in the last few years on glucagon-like peptide-1 analogs and the new family of oral drugs known as gliflozins, specifically studies published on dapagliflozin.

Volume and outcome relationship in bariatric surgery in the laparoscopic era

The relationship between volume and outcomes in bariatric surgery is well established in the literature. However, the analyses were performed primarily in the open surgery era and in the absence of national accreditation. The recent Metabolic Bariatric Surgery Accreditation and Quality Improvement Program proposed an annual threshold volume of 50 stapling cases. This study aimed to examine the effect of volume and accreditation on surgical outcomes for bariatric surgery in this laparoscopic era. The Nationwide Inpatient Sample was used for analysis of the outcomes experienced by morbidly obese patients who underwent an elective laparoscopic stapling bariatric surgical procedure between 2006 and 2010. In this analysis, low-volume centers (LVC < 50 stapling cases/year) were compared with high-volume centers (HVC ≥ 50 stapling cases/year). Multivariate analysis was performed to examine risk-adjusted serious morbidity and in-hospital mortality between the LVCs and HVCs. Additionally, within the HVC group, risk-adjusted outcomes of accredited versus nonaccredited centers were examined. Between 2006 and 2010, 277,760 laparoscopic stapling bariatric procedures were performed, with 85% of the cases managed at HVCs. The mean number of laparoscopic stapling cases managed per year was 17 ± 14 at LVCs and 144 ± 117 at HVCs. The in-hospital mortality was higher at LVCs (0.17%) than at HVCs (0.07%). Multivariate analysis showed that laparoscopic stapling procedures performed at LVCs had higher rates of mortality than those performed at HVCs [odds ratio (OR) 2.5; 95% confidence interval (CI) 1.3-4.8; p < 0.01] as well as higher rates of serious morbidity (OR 1.2; 95% CI 1.1-1.4; p < 0.01). The in-hospital mortality rate at nonaccredited HVCs was 0.22% compared with 0.06% at accredited HVCs. Multivariate analysis showed that nonaccredited centers had higher rates of mortality than accredited centers (OR 3.6; 95% CI 1.5-8.3; p < 0.01) but lower rates of serious morbidity (OR 0.8; 95% CI 0.7-0.9; p < 0.01). In this era of laparoscopy, hospitals managing more than 50 laparoscopic stapling cases per year have improved outcomes. However, nonaccredited HVCs have outcomes similar to those of LVCs. Therefore, the impact of accreditation on outcomes may be greater than that of volume.

Impact of bariatric surgery on the management of type 2 diabetes mellitus in Singapore

Obesity is a risk factor for type 2 diabetes mellitus (T2DM). Metabolic-bariatric surgery (MBS) results in significant weight loss with dramatic improvement in T2DM. This study analysed the effects of MBS on patients with T2DM in a tertiary centre in Singapore. Individuals with T2DM who underwent MBS in a single centre from September 2008 to May 2012, with at least 12 months of regular follow-up, were included in our study. The primary outcome measure was good glycaemic control (glycated haemoglobin [HbA1c] < 6.5%, with or without medications) 12 months after surgery. Secondary outcome measures were partial DM remission (fasting blood glucose [FBG] < 7.0 mmol/L and HbA1c < 6.5% without DM medications), complete DM remission (FBG < 5.6 mmol/L and HbA1c < 6.0% without DM medications), weight, body mass index, blood pressure, and fasting serum lipid, serum glucose and serum insulin levels. Of the 19 patients who met the inclusion criteria, 14 underwent gastric bypass and 5 underwent sleeve gastrectomy. At 12 months postoperatively, 17 (89.5%) patients achieved good glycaemic control. DM remission was achieved in 14 (73.7%) patients, with 10 (52.6%) attaining complete remission. In Singapore, MBS is an effective treatment modality for obese patients with T2DM. Despite the small sample size and lack of matched controls, the present study suggests that MBS is effective in achieving significant weight loss and eliciting a significant and sustainable improvement in the glycaemic control of patients with T2DM, for up to 12 months.

Metabolic Bone Disease and Bariatric Surgery

The prevalence of obesity is increasing worldwide and the past decade has witnessed an exponential rise in the number of bariatric operations performed. As a consequence, it is expected that an increasing number of patients are likely to be at risk of long term complications that may not manifest until years or decades later. Several studies have investigated the short and long-term complications of bariatric surgery but there is little available data on the longterm consequences on bone metabolism and the consequences of this after bariatric surgery. This paper reviews the current literature for further information on this clinically relevant issue.

Metabolic Bone Disease and Bariatric Surgery

The prevalence of obesity is increasing worldwide and the past decade has witnessed an exponential rise in the number of bariatric operations performed. As a consequence, it is expected that an increasing number of patients are likely to be at risk of long term complications that may not manifest until years or decades later. Several studies have investigated the short and long-term complications of bariatric surgery but there is little available data on the longterm consequences on bone metabolism and the consequences of this after bariatric surgery. This paper reviews the current literature for further information on this clinically relevant issue.

Metabolic-Bariatric Surgery: An Emerging Specialty

After the end of the second world war, the world saw a significant period of growth and prosperity unlike any previously. By the 1950s, morbid obesity was proving to be a clinical problem in many developed societies in Europe and North America. Diet, lifestyle and medication alone did not appear to be effective in controlling morbid obesity, and surgical interventions were developed. Surgical therapies to combat the epidemic of obesity evolved from intestinal bypasses (which had the potential for serious fluid, electrolyte and nutritional disturbances) to eventually settle on manipulations that involve restrictive procedures of the stomach with or without bypass of the duodenum and jejunum. This branch of surgery was referred to as “bariatric” (from the Greek “baros” for weight), but recent awareness that concomitant obesity-related metabolic diseases can also be effectively treated by these procedures has given rise to the new specialty of metabolic-bariatric surgery (MBS). This review looks at current MBS procedures and their impact on gastro-intestinal physiology to achieve both weight loss and metabolic control.

Role of Bariatric-Metabolic Surgery in the Treatment of Obese Type 2 Diabetes with Body Mass Index &lt;35 kg/m2: A Literature Review

Bariatric surgery has been used to treat type 2 diabetes mellitus (T2DM); however, its efficacy is still debatable. This literature review analyzed articles that evaluated the effects of bariatric surgery in treatment of T2DM in obese patients with a body mass index (BMI) of <35 kg/m(2). A paired t test was applied for the analysis of pre- and postintervention mean BMI, fasting plasma glucose (FPG), and glycosylated hemoglobin (A1c) values. A significant (P<0.001) reduction in BMI (from 29.95±0.51 kg/m(2) to 24.83±0.44 kg/m(2)), FPG (from 207.86±8.51 mg/dL to 113.54±4.93 mg/dL), and A1c (from 8.89±0.15% to 6.35±0.18%) was observed in 29 articles (n=675). T2DM resolution (A1c <7% without antidiabetes medication) was achieved in 84.0% (n=567) of the subjects. T2DM remission, control, and improvement were observed in 55.41%, 28.59%, and 14.37%, respectively. Only 1.63% (n=11) of the subjects presented similar or worse glycemic control after the surgery. T2DM remission (A1c <6% without antidiabetes medication) was higher after mini-gastric bypass (72.22%) and laparoscopic/Roux-en-Y gastric bypass (70.43%). According to the Foregut and Hindgut Hypotheses, T2DM results from the imbalance between the incretins and diabetogenic signals. The procedures that remove the proximal intestine and do ileal transposition contribute to the increase of glucagon-like peptide-1 levels and improvement of insulin sensitivity. These findings provide preliminary evidence of the benefits of bariatric-metabolic surgery on glycemic control of T2DM obese subjects with a BMI of <35 kg/m(2). However, more clinical trials are needed to investigate the metabolic effects of bariatric surgery in T2DM remission on pre-obese and obese class I patients.

A Comment on the International Diabetic Federation Statement

To the Editors Dr. Walter Pories, a great pioneer in the development of bariatric into metabolic surgery [1], has provided major suggestions [2]) to the recent International Diabetes Federation (IDF) guidelines for metabolic surgery for type 2 diabetes (T2D) [3]. The remission of T2D after weight loss operations has long been recognized [4, 5], but the formal IDF position statement is a milestone. Importantly, Nicola Scopinaro, performing biliopancreatic diversion, has found an extremely high remission rate for T2D in diabetics with lower BMI [6]). There is one instance where the IDF guidelines require some caution. The position statement mentions in a table on management of diabetes near the end that there should be an audit of C-peptide and autoantibody status, e.g., antiGAD where available [3]). However, this assertion is not explained. A problem which can harm the use of metabolic surgery for meaningful remission of T2D is if the patient actually has a type 1 diabetes. Latent autoimmune diabetes in the adult (LADA) may have slow onset generally between ages 30 and 55, at any weight, and will ultimately progress to requiring insulin [7]. LADA is an explanation for some cases of diabetes at lower BMI. This type 1 diabetes should be diagnosed by very low fasting and/or meal-stimulated C-peptide (≤1 ng/ml), low plasma insulin, and presence of autoantibodies to glutamic acid decarboxylase (GAD), islet cells, insulin and/or insulin A2 [8]. These patients have relentless autoimmune destruction of the pancreas and may have other autoimmune disorders. Lee, Boza and Basso’s groups [9–11] exclude diabetic patients with low C-peptide (an indication of low beta-cell function) from bariatric metabolic surgery. Longstanding uncontrolled T2D with HbA1c of 10, despite initial insulin resistance/hyperinsulinemia, will eventually be unable to increase insulin response to signaling, as a result of betacell apoptosis [5]). This T2D will require insulin. However, Shashank Shah has noted that in those South Asian diabetics whose BMI is lower and have a lower body fat percentage (personal communication, Sept. 28, 2011), type 1 diabetes must be considered [12]. For metabolic operations to result in a significant and sustained remission of diabetes, especially in those presenting with lower BMI, adult-onset type 1 diabetes should first be ruled out.

Status of venous thromboembolism prophylaxis among bariatric surgeons: have we changed our practice during the past decade?

Background Venous thromboembolism (VTE) is considered one of the principal causes of morbidity and mortality in patients requiring bariatric surgery. A survey to all members of the American Society for Metabolic and Bariatric Surgery was conducted in 1998 and published in 2000 in the journal “Obesity Surgery.” Methods A survey was repeated to all physician members of the American Society for Metabolic and Bariatric Surgery to determine the current practices for VTE prophylaxis. The results were compared with those of the previous study. Results Of the members, 35% completed the survey for a total of 332 responses. The number of cases annually per surgeon almost doubled since 1998 (145 versus 85). Laparoscopic gastric bypass has replaced open gastric bypass as the most common procedure performed, followed by laparoscopic gastric banding as the second most common procedure. Most surgeons (95%) use chemical prophylaxis to prevent VTE, but almost 60% preferred low-molecular-weight heparin compared with 13% in 1998. More than 60% of bariatric surgeons discharged their patients with chemical prophylaxis compared with 12% in 1998. Inferior vena cava filters for prophylaxis are considered by 55% compared with only 7% in 1998. The incidence of reported deep vein thrombosis was significantly lower in 2007 (2.635 versus .93), as was the incidence of pulmonary embolism (.95% versus .75%). Almost 50% of surgeons still reported ≥1 fatality because of VTE complications. Conclusion Chemical prophylaxis for VTE with some type of heparin is the standard of care for patients undergoing bariatric surgery. Low-molecular-weight heparin is now used by two thirds of the respondents to this survey. Most surgeons who responded to the survey discharged their patients home with heparin, and many consider the use of inferior vena cava filters for VTE prophylaxis. Our findings support the American Society for Metabolic Bariatric Surgery position statement regarding VTE prophylaxis in this patient population. Research is necessary to establish the role of inferior vena cava filters, discharging patients with chemoprophylaxis and to determine the adequate dosage and duration of prophylaxis.