Gastrointestinal surgery as a treatment for diabetes

The Role of Metabolic Surgery in Non-alcoholic Steatohepatitis Improvement

PURPOSE OF REVIEW

Non-alcoholic fatty liver disease (NAFLD) is frequently associated with obesity and overweight. It has a broad spectrum of clinical and histological presentations, such as steatosis, inflammation (known as non-alcoholic steatohepatitis or NASH), fibrosis, and cirrhosis. There is increasing evidence that marked weight loss following bariatric surgery is associated with NASH resolution; however, little is known about the mechanisms that may lead to this beneficial condition and if it is due to weight loss alone. In this review, the authors present the latest data regarding NASH resolution following metabolic surgery and try to answer the following questions: is NASH resolution due to weight loss alone or is it related to weight-independent effects similarly to T2D? In such case, can NASH be considered as a sole criterion for metabolic surgery?

RECENT FINDINGS

Most data evaluating NAFLD and bariatric and metabolic surgery are derived from cohort studies. Available data are extremely variable, but in general show a dramatic regression of steatosis, inflammatory changes, and in some cases even fibrosis that is probably linked to major weight loss following surgery. There are no randomized controlled trials evaluating the effects of metabolic surgery over NASH vs. lifestyle modifications. To consider NASH a sole indication for metabolic surgery regardless of BMI, such studies are desperately needed and should be the primary focus of future research in metabolic surgery.

The Effects of One-Anastomosis Gastric Bypass on Glucose Metabolism in Goto-Kakizaki Rats

BACKGROUND

The improvement in glucose metabolism after bariatric surgery is well established. The aim of this study was to investigate the hormones and glycemic control in diabetes after a one-anastomosis gastric bypass (OAGB) variant in an animal model of non-obese type 2 diabetes mellitus.

METHODS

Thirty-six Goto-Kakizaki rats were randomly assigned to undergo one of the following procedures: OAGB (18 rats) or sham intervention (18 rats). Each group was subdivided into three additional groups according to the time of surgery (early-12 weeks; intermediate-16 weeks; and late-20 weeks). Weight, fasting glycemia, glucose tolerance test (OGTT), and hormone levels (glucagon, insulin, glucagon-like peptide-1 [GLP-1], and glucose-dependent insulinotropic peptide [GIP]) were measured.

RESULTS

All rats maintained their weight. The OGTT showed a significant improvement in glycemic levels in rats with OAGB in all time groups (p < 0.002, for all groups at 60 min). Insulin levels decreased significantly in all animals with OAGB, but glucagon levels increased (glucagon paradoxical response). GLP-1 and GIP increased in rats with OAGB at all times, but was only statistically significant in the early surgery group of GLP-1 (p < 0.005).

CONCLUSION

OAGB in a non-obese diabetic rat model improves glycemic control, with a significant decrease in glucose and insulin levels. This reduction without weight loss suggests a surgically induced enhancement of pancreatic function. It appears that this improvement occurs, although the GLP-1 levels were significantly increased only in the early stages. The paradoxical response of glucagon should be further evaluated.

Metabolic surgery: gastric bypass for the treatment of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is one of the largest health emergencies of the 21st century given the worldwide increase of obesity during the last decades and its close association. T2DM is an inherited, polygenic and chronic disease caused by the interaction between several genetic variants in genes and the environment. The continuous search for new and more effective tools to achieve appropriate glycemic control became imperative in order to reduce long-term complications and mortality rates related to T2DM. Treatment options includes lifestyle modifications and several pharmacotherapies as first step in the therapeutical algorithm, but high corps of evidence have shown that gastrointestinal (GI) operations, especially those that involve food rerouting through the GI tract, are safe interventions and achieve superior outcomes for improvement in glucose metabolism when comparing with optimal medical and lifestyle changes. GI Surgery, specially Roux-en-Y gastric bypass (RYGB), is currently the most accepted surgical procedure to treat T2DM, and has also demonstrated to reduce significantly other cardiovascular risk factors (lipids and blood pressure control) when compared with optimal medical treatment, with good long-term effects on cardiovascular risks and mortality. Although the most effective technique in achieving diabetes remission is biliopancreatic diversion, the effectiveness-adverse effects balance is superior for RYGB. For these reasons, metabolic surgery (which was defined as "the operative manipulation of a normal organ or organ system to achieve a biological result for a potential health gain") has been considered and accepted as a new step in the therapeutic algorithm for T2DM when optimal lifestyle and medical interventions don't achieve optimal glycemic goals.

THE ROLE OF METABOLIC SURGERY FOR PATIENTS WITH OBESITY GRADE I AND TYPE 2 DIABETES NOT CONTROLLED CLINICALLY

Introduction

Even considering the advance of the medical treatment in the last 20 years with new and more effective drugs, the outcomes are still disappointing as the control of obesity and type 2 Diabetes Mellitus (T2DM) with a large number of patients under the medical treatment still not reaching the desired outcomes.

Objective:

To present a Metabolic Risk Score to better guide the surgical indication for T2DM patients with body mass index (BMI) where surgery for obesity is still controversial.

Method:

Research was conducted in Pubmed, Medline, Pubmed Central, Scielo and Lilacs between 2003-2015 correlating headings: metabolic surgery, obesity and type 2 diabetes mellitus. In addition, representatives of the societies involved, as an expert panel, issued opinions.

Results:

Forty-five related articles were analyzed by evidence-based medicine criteria. Grouped opinions sought to answer the following questions: Why metabolic and not bariatric surgery?; Mechanisms involved in glycemic control; BMI as a single criterion for surgical indication for uncontrolled T2DM; Results of metabolic surgery studies in BMI<35 kg/m²; Safety of metabolic surgery in patients with BMI<35 kg/m²; Long-term effects of surgery in patients with baseline BMI<35 kg/m² and Proposal for a Metabolic Risk Score.

Conclusion:

Metabolic surgery has well-defined mechanisms of action both in experimental and human studies. Gastrointestinal interventions in T2DM patients with IMC≤35 kg/m² has similar safety and efficacy when compared to groups with greater BMIs, leading to the improvement of diabetes in a superior manner than clinical treatment and lifestyle changes, in part through weight loss independent mechanisms . There is no correlation between baseline BMI and weight loss in the long term with the success rate after any surgical treatment. Gastrointestinal surgery treatment may be an option for patients with T2DM without adequate clinical control, with a BMI between 30 and 35, after thorough evaluation following the parameters detailed in Metabolic Risk Score defined by the surgical societies. Roux-en-Y gastric bypass (RYGB), because of its well known safety and efficacy and longer follow-up studies, is the main surgical technique indicated for patients eligible for surgery through the Metabolic Risk Score. The vertical sleeve gastrectomy may be considered if there is an absolute contraindication for the RYGB. T2DM patients should be evaluated by the multiprofessional team that will assess surgical eligibility, preoperative work up, follow up and long term monitoring for micro and macrovascular complications.

Clinical Outcomes of Metabolic Surgery: Microvascular and Macrovascular Complications

Understanding of the long-term clinical outcomes associated with bariatric surgery has recently been advanced. Research related to the sequelae of diabetes-in particular, long-term microvascular and macrovascular complications-in patients who undergo weight-loss surgery is imperative to this pursuit. While numerous randomized control trials have assessed glucose control with bariatric surgery compared with intensive medical therapy, bariatric surgery outcome data relating to microvascular and macrovascular complications have been limited to observational studies and nonrandomized clinical trials. As a result, whether bariatric surgery is associated with a long-term reduction in microvascular and macrovascular complications when compared with current intensive glycemic control therapy cannot be determined because the evidence is insufficient. However, the consistent salutary effects of bariatric surgery on diabetes remission and glycemic improvement support the opportunity (and need) to conduct high-quality studies of bariatric surgery versus intensive glucose control. This review provides relevant background information related to the treatment of diabetes, hyperglycemia, and long-term complications; reports clinical findings (to date) with bariatric surgery; and identifies ongoing research focusing on long-term vascular outcomes associated with bariatric surgery.

Role of metabolic surgery in less obese or non-obese subjects with type 2 diabetes: influence over cardiovascular events

Bariatric surgery was initially developed as a tool for weight reduction only, but it is gaining increasing popularity because of its remarkable effect on glucose metabolism in morbidly obese and less obese patients. Recent publications have shown the good results of metabolic surgery, creating a new field of clinical research that is currently overflowing in the medical community with outstanding high-quality data. In morbidly obese population, there is compelling data on long term cardiovascular risk reduction and mortality, coming from longitudinal prospective studies and systematic reviews. Numbers range from 33 to 92% of decrease in fatal and nonfatal cardiovascular events . In low body mass index (BMI) diabetics, there is an increasing number of reported good outcomes after metabolic surgery with the aim to treat type 2 diabetes (T2DM). There is scarce information on cardiovascular outcomes in non-morbidly obese subjects, but the extraordinary glucose, lipid and blood pressure control in the published series are suggesting good long-term effects on cardiovascular risk profile and mortality. The papers review was comprehensive, including the available randomized controlled trials, long-term prospective series and systematic reviews.

Metabolic Surgery for Type 2 Diabetes in Patients with a BMI of <35 kg/m(2): A Surgeon's Perspective

Bariatric surgery was developed with the aim of weight reduction. Success was defined only by excess weight loss. Other indices of resolution of metabolic comorbidities were reported, but were mostly secondary. Several communications have reported that regardless of body mass index (BMI), complete or partial remission of type 2 diabetes mellitus (T2DM) is possible. These results mostly occur before weight loss, positioning metabolic surgery as a good tool for controlling the current T2DM epidemic. Medical treatment is evolving, but is expensive and not risk-free. Surgery aimed mainly at diseases such as diabetes and not weight loss are referred to as "metabolic surgery." Metabolic surgery has been proven to be safe and effective, and although more data are needed, it is unquestionable that a new discipline has been founded. Metabolic surgery can effectively treat T2DM in individuals with any BMI, including that below 35 kg/m(2).

Evaluating the mechanisms of improved glucose homeostasis after bariatric surgery in Ossabaw miniature swine

BACKGROUND

Roux-en-Y gastric bypass (RYGB) is the most common bariatric operation; however, the mechanism underlying the profound weight-independent effects on glucose homeostasis remains unclear. Large animal models of naturally occurring insulin resistance (IR), which have been lacking, would provide opportunities to elucidate such mechanisms. Ossabaw miniature swine naturally exhibit many features that may be useful in evaluating the anti diabetic effects of bariatric surgery.

METHODS

Glucose homeostasis was studied in 53 Ossabaw swine. Thirty-two received an obesogenic diet and were randomized to RYGB, gastrojejunostomy (GJ), gastrojejunostomy with duodenal exclusion (GJD), or Sham operations. Intravenous glucose tolerance tests and standardized meal tolerance tests were performed prior to, 1, 2, and 8 weeks after surgery and at a single time-point for regular diet control pigs.

RESULTS

High-calorie-fed Ossabaws weighed more and had greater IR than regular diet controls, though only 70% developed IR. All operations caused weight-loss-independent improvement in IR, though only in pigs with high baseline IR. Only RYGB induced weight loss and decreased IR in the majority of pigs, as well as increasing AUCinsulin/AUCglucose.

CONCLUSIONS

Similar to humans, Ossabaw swine exhibit both obesity-dependent and obesity-independent IR. RYGB promoted weight loss, IR improvement, and increased AUCinsulin/AUCglucose, compared to the smaller changes following GJ and GJD, suggesting a combination of upper and lower gut mechanisms in improving glucose homeostasis.

Cooperation between brain and islet in glucose homeostasis and diabetes

Although a prominent role for the brain in glucose homeostasis was proposed by scientists in the nineteenth century, research throughout most of the twentieth century focused on evidence that the function of pancreatic islets is both necessary and sufficient to explain glucose homeostasis, and that diabetes results from defects of insulin secretion, action or both. However, insulin-independent mechanisms, referred to as 'glucose effectiveness', account for roughly 50% of overall glucose disposal, and reduced glucose effectiveness also contributes importantly to diabetes pathogenesis. Although mechanisms underlying glucose effectiveness are poorly understood, growing evidence suggests that the brain can dynamically regulate this process in ways that improve or even normalize glycaemia in rodent models of diabetes. Here we present evidence of a brain-centred glucoregulatory system (BCGS) that can lower blood glucose levels via both insulin-dependent and -independent mechanisms, and propose a model in which complex and highly coordinated interactions between the BCGS and pancreatic islets promote normal glucose homeostasis. Because activation of either regulatory system can compensate for failure of the other, defects in both may be required for diabetes to develop. Consequently, therapies that target the BCGS in addition to conventional approaches based on enhancing insulin effects may have the potential to induce diabetes remission, whereas targeting just one typically does not.

Effect of laparoscopic Roux-en-Y gastric bypass on glucose metabolism in obese patients with type 2 diabetes mellitus

AIM: To investigate the effect of laparoscopic Roux-en-Y gastric bypass (LRYGB) on glucose metabolism in obese patients with type 2 diabetes mellitus.

METHODS: Twenty obese patients with type 2 diabetes mellitus underwent LRYGB. Fasting blood glucose (FBG), 2-hour postprandial blood glucose (2 h PBG), C peptide (C-P), glycosylated hemoglobin (HbA1C) and fasting insulin (Fins) were recorded before surgery and at the 1^st, 4^th, 8^th, 12^th, and 24^th week after surgery. Insulin resistance index (HOMA-IR) was calculated and compared.

RESULTS: LRYGB was successful in all the patients, without intraoperative complications or conversion to open surgery. FBG decreased from 11.25 mmol/L ± 3.36 mmol/L before surgery to 6.21 mmol/L ± 0.52 mmol/L at the 24^th week after surgery (P < 0.05), 2 h PBG from 15.33 mmol/L ± 2.54 mmol/L to 8.78 mmol/L ± 1.51 mmol/L (P < 0.05), HbA1C from 9.05% ± 1.27% to 6.53% ± 0.58% (P < 0.05), HOMA-IR from 7.16 ± 0.65 to 3.84 ± 0.47 (P < 0.05), and Fins increased from 11.24 mU/L ± 0.98 mU/L to 12.03 mU/L ± 0.75 mU/L (P > 0.05). The total effective rate was 100%, the recovery rate was 85%, and the improvement rate was 15%.

CONCLUSION: LRYGB can significantly reduce plasma glucose levels and improve glucose metabolism in obese patients with type 2 diabetes mellitus.

Partial small bowel resection with sleeve gastrectomy increases adiponectin levels and improves glucose homeostasis in obese rodents with type 2 diabetes

BACKGROUND

The aim of this study was to examine the effect of small bowel resection with and without sleeve gastrectomy on glucose homeostasis in an obese rodent model of type 2 diabetes.

METHODS

Zucker diabetic fatty rats were randomized into three surgical groups: Sham, small bowel resection, and small bowel resection with sleeve gastrectomy (BRSG). Weight and fasting glucose levels were measured at randomization and monitored after surgery. Oral glucose tolerance testing was performed at baseline and 45 days after surgery to assess glucose homeostasis and peptide changes.

RESULTS

At baseline, all animals exhibited impaired glucose tolerance and showed no difference in weight or fasting (area under the curve) AUC(glucose). At sacrifice, Sham animals weighed more than BRSG animals (p = 0.047). At day 45, the Sham group experienced a significant increase in AUC(glucose) compared to baseline (p = 0.02), whereas there was no difference in AUC(glucose) in either surgical group at any time point: BR (p = 0.58) and BRSG (p = 0.56). Single-factor ANOVA showed a significant difference in AUC(glucose) of p = 0.004 between groups postoperatively: Sham (50,745 ± 11,170) versus BR (23,865 ± 432.6) (p = 0.01); Sham versus BRSG (28,710 ± 3188.8) (p = 0.02). There was no difference in plasma insulin, GLP-1, or adiponectin levels before surgery, although 45 days following surgery adiponectin levels where higher in the BRSG group (p = 0.004).

CONCLUSIONS

Partial small bowel resection improved glucose tolerance independent of weight. The combination of small bowel resection and sleeve gastrectomy leads to an increase in adiponectin levels, which may contribute to improved glucose homeostasis.

Effects of gastric bypass surgery in patients with type 2 diabetes and only mild obesity

OBJECTIVE

Roux-en-Y gastric bypass (RYGB) ameliorates type 2 diabetes in severely obese patients through mechanisms beyond just weight loss, and it may benefit less obese diabetic patients. We determined the long-term impact of RYGB on patients with diabetes and only class I obesity.

RESEARCH DESIGN AND METHODS

Sixty-six consecutively selected diabetic patients with BMI 30-35 kg/m(2) underwent RYGB in a tertiary-care hospital and were prospectively studied for up to 6 years (median 5 years [range 1-6]), with 100% follow-up. Main outcome measures were safety and the percentage of patients experiencing diabetes remission (HbA(1c) <6.5% without diabetes medication).

RESULTS

Participants had severe, longstanding diabetes, with disease duration 12.5 ± 7.4 years and HbA(1c) 9.7 ± 1.5%, despite insulin and/or oral diabetes medication usage in everyone. For up to 6 years following RYGB, durable diabetes remission occurred in 88% of cases, with glycemic improvement in 11%. Mean HbA(1c) fell from 9.7 ± 1.5 to 5.9 ± 0.1% (P < 0.001), despite diabetes medication cessation in the majority. Weight loss failed to correlate with several measures of improved glucose homeostasis, consistent with weight-independent antidiabetes mechanisms of RYGB. C-peptide responses to glucose increased substantially, suggesting improved β-cell function. There was no mortality, major surgical morbidity, or excessive weight loss. Hypertension and dyslipidemia also improved, yielding 50-84% reductions in predicted 10-year cardiovascular disease risks of fatal and nonfatal coronary heart disease and stroke.

CONCLUSIONS

This is the largest, longest-term study examining RYGB for diabetic patients without severe obesity. RYGB safely and effectively ameliorated diabetes and associated comorbidities, reducing cardiovascular risk, in patients with a BMI of only 30-35 kg/m(2).

Glycemic control after stomach-sparing duodenal-jejunal bypass surgery in diabetic patients with low body mass index

BACKGROUND

Bariatric surgery frequently results in the resolution of type 2 diabetes mellitus (T2DM). One of the many factors that could explain such findings is the duodenal exclusion of the alimentary tract. To test this hypothesis, a surgical model that induces glycemic control without significant weight loss would be ideal. In the present study, we evaluated the early metabolic changes that occur in overweight diabetic patients after laparoscopic duodenal-jejunal bypass (DJB) and determined the factors associated with success in T2DM resolution. The setting was a private practice.

METHODS

A total of 35 patients (20 men and 15 women) were included in the present study. The mean preoperative body mass index was 28.4 ± 2.9 kg/m(2). DJB was performed in all patients, and the anthropometric data and blood samples were collected at baseline (preoperatively) and 3, 6, 9, and 12 months after surgery. Success was defined when patients reached a glycated hemoglobin level of <7% without diabetic medication.

RESULTS

T2DM remission was observed in 14 (40%) of 35 patients. No differences in the homeostasis model assessment insulin resistance index levels and patient weight were observed before and 12 months after DJB surgery. Gender, duration of T2DM, previous use of insulin, preoperative homeostasis model assessment insulin resistance index, and C-peptide levels were not significant predictive factors of success or nonsuccess. The only factor that significantly predicted postoperative positive outcomes was a waist circumference reduction of ≥ 7% compared with baseline within the first 6 months after surgery.

CONCLUSION

DJB improves glycemic control; however, it does not increase insulin sensitivity in overweight diabetic patients. These changes were observed without significant weight loss.

Gastric bypass surgery improves glucose metabolism possibly by decreasing ghrelin levels in Goto-Kakizaki rats

AIM: To investigate the influence of gastric bypass (GBP) surgery on glucose metabolism in Goto-Kakizaki (GK) rats and to explore the possible mechanisms involved.

METHODS: Twenty male GK rats and 10 male Wistar rats were randomized into three groups: GK operation group, GK sham operation group and Wistar sham operation group. The GK operation group underwent gastric bypass surgery. The levels of fasting plasma glucose (FPG), glycosylated hemoglobin (HbAlc), serum insulin (INS) and ghrelin were monitored 1 week before surgery and 1, 2, 4, 8 and 12 weeks after surgery.

RESULTS: In the GK operation group, FPG level decreased from (11.36 ± 1.14) mmol/L before surgery to (8.36 ± 0.62) mmol/L 12 weeks after surgery, and HbAlc from (8.91 ± 0.36)% to (6.35 ± 0.46)%. Serum INS increased from (32.70 ± 2.37) mIU/L before surgery to (55.14 ± 5.45) mIU/L 12 weeks after surgery, while serum ghrelin level decreased from (928.53 ± 58.66) pg/mL to (367.83 ± 27.78) pg/mL. All the above parameters differed significantly between before surgery and 12 weeks after surgery (all P < 0.05).

CONCLUSION: GBP can significantly improve glycometabolism in GK rats possibly by decreasing ghrelin levels and promoting insulin secretion.

Bariatric surgery for type 2 diabetes: weighing the impact for obese patients

Obesity is a potent risk factor for the development and progression of type 2 diabetes, and weight loss is a key component of diabetes management. Bariatric surgery results in significant weight loss and remission of diabetes in most patients. After surgery, glycemic control is restored by a combination of enforced caloric restriction, enhanced insulin sensitivity, and increased insulin secretion.

Bariatric surgery in patients with type 2 diabetes: a viable option

The prevalence of obesity is increasing and is co-epidemic with type 2 diabetes mellitus (T2DM). Treatment of obesity has been less than adequate, particularly when managing morbidly obese patients. Research on T2DM has shown a number of new pharmacologic therapies along with the rapid employment of bariatric surgery. Improvement of T2DM, including its remission, after bariatric surgery has been recognized for more than a decade. However, not all procedures are the same. Restrictive procedures, malabsorptive procedures, or a combination of both procedures have their own categorical risks and benefits. Which procedure to choose has to do with many patient selection factors, notwithstanding insurance coverage. Based on operative and postoperative mortality data, laparoscopically assisted gastric bypass (LAGB) has been shown to be the safest bariatric surgery procedure. However, the Roux-en-Y gastric bypass procedure is one of the most widely used for obese patients with T2DM. The mechanisms involved in weight loss and improved blood glucose control appear to involve increased insulin sensitivity, decreased lipotoxicity/inflammation, and changes in gut hormones/incretins. The safety of bariatric procedures has improved; complication rates are low and mortality is < 1% for all procedures. As a result of the dramatic, positive impact of bariatric procedures on T2DM in obese patients, physicians should be cautious during patient selection to avoid performing the procedure on patients who are overzealous about reported outcomes, but who are not candidates for the procedure. Other data gaps still exist regarding diabetes surgery, which must be filled using data from well-designed, well-implemented randomized controlled clinical trials. In the future, it will be prudent to compare surgical interventions with other rigorous medical interventions in more robust studies. A combination of surgical, medical, and behavioral interventions should be considered for treating obese patients with T2DM.

Biliopancreatic diversion with duodenal switch in patients with type 2 diabetes mellitus: is the chance of complete remission dependent on therapy and duration of insulin treatment?

BACKGROUND

Rapid resolution of type 2 diabetes mellitus (T2DM) is a common feature after intestinal bypass surgery bypassing the duodenum and parts of the jejunum. However, the parameters determining the individual chance of remission are imprecisely defined.

METHODS

Biliopancreatic diversion with duodenal switch and sleeve gastrectomy (BPD-DS) was performed in n = 86 patients with T2DM (mean age 50 years, range 26-68, 51 females; BMI 47 kg/m(2), range 26-71). The patients were retrospectively divided into 4 groups according to the treatment modality and the duration of insulin treatment preoperatively: n = 18 patients were treated with oral antidiabetic drugs only (group 1); n = 32, n = 24, and n = 12 patients were treated with insulin for less than 5 years, for 5-10 years, and for more than 10 years (groups 2, 3, and 4), respectively.

RESULTS

At discharge from hospital, all patients of groups 1 and 2 were free of insulin usage, 30% and 75% of the patients of groups 3 and 4 used up to 48 units of insulin per day (mean 24, n = 16). After 1 year, only 4 patients of group 4 permanently required small amounts of insulin (mean 17 units per day) to keep blood glucose below 200 mg/dl. These 4 patients had been using insulin preoperatively for 13, 15, 22, and 25 years. In 3 of these 4 patients, fasting C-peptide was measured and found to be low (<1.2 ng/ml). The rate of complete remission of diabetes for the whole study population was 91%.

CONCLUSION

BPD-DS reliably causes rapid and complete remission of T2DM in all patients on oral antidiabetic drugs and in patients with insulin treatment for less than 5 years. In patients with insulin treatment longer than 5 or 10 years, complete remission rates decline to 88 and 66%, respectively. A low C-peptide preoperatively might be a specific adverse prognostic parameter for the chance of diabetes remission.

Metabolic surgery and cancer: protective effects of bariatric procedures

The worldwide epidemic of obesity and the global incidence of cancer are both increasing. There is now epidemiological evidence to support a correlation between obesity, weight gain, and some cancers. Metabolic or bariatric surgery can provide sustained weight loss and reduced obesity-related mortality. These procedures can also improve the metabolic profile to decrease cardiovascular risk and resolve diabetes in morbidly obese patients. The operations offer several physiological steps, the so-called BRAVE effects: 1) bile flow alteration, 2) reduction of gastric size, 3) anatomical gut rearrangement and altered flow of nutrients, 4) vagal manipulation and 5) enteric gut hormone modulation. Metabolic operations are also associated with a significant reduction of cancer incidence and mortality. The cancer-protective role of metabolic surgery is strongest for female obesity-related tumors; however, the underlying mechanisms may involve both weight-dependent and weight-independent effects. These include the improvement of insulin resistance with attenuation of the metabolic syndrome as well as decreased oxidative stress and inflammation in addition to the beneficial modulation of sex steroids, gut hormones, cellular energetics, immune system, and adipokines. Elucidating the precise metabolic mechanisms of cancer prevention by metabolic surgery can increase our understanding of how obesity, diabetes, and metabolic syndrome are associated with cancer. It may also offer novel treatment strategies in the management of tumor generation and growth.

Mechanisms facilitating weight loss and resolution of type 2 diabetes following bariatric surgery

Bariatric surgery is the most effective treatment modality for obesity, resulting in durable weight loss and amelioration of obesity-associated comorbidities, particularly type 2 diabetes mellitus (T2DM). Moreover, the metabolic benefits of bariatric surgery occur independently of weight loss. There is increasing evidence that surgically induced alterations in circulating gut hormones mediate these beneficial effects of bariatric surgery. Here, we summarise current knowledge on the effects of different bariatric procedures on circulating gut hormone levels. We also discuss the theories that have been put forward to explain the weight loss and T2DM resolution following bariatric surgery. Understanding the mechanisms mediating these beneficial outcomes of bariatric surgery could result in new non-surgical treatment strategies for obesity and T2DM.

Surgical approaches for the prevention and treatment of type 2 diabetes mellitus

Lifestyle modifications and pharmacologic therapy have been the mainstays of treatment for patients with type 2 diabetes mellitus. Bariatric surgery, originally designed as a weight loss treatment, has been proven to ameliorate and even cure diabetes. The significant improvement in glycemic control found after bariatric surgery in patients with diabetes often precedes major weight loss. Therefore, a weight-independent mechanism has been thought to initiate this amelioration in glucose control. Reviews of the recent literature question the goal of bariatric surgery, not only to treat obesity through restriction and malabsorption, but also as a possible treatment for diabetes regardless of the degree of obesity. Procedures such as Roux-en-Y gastric bypass, adjustable gastric banding, and biliopancreatic diversion have proven to be extremely effective in controlling diabetes mellitus. Mechanisms explaining the effectiveness of weight reduction surgery include effects on incretins, ghrelin secretion, and insulin sensitivity. Some centers have been performing gastric bypass surgeries on patients with a lower body mass index than that recommended by current NIH guidelines. New considerations for recommending bypass surgery are warranted as the indications for antiobesity surgeries grow to encompass both the treatment and cure of diabetes.

Insulin therapy and type 2 diabetes: management of weight gain

The potential for insulin-related weight gain in patients with type 2 diabetes presents a therapeutic dilemma and frequently leads to delays in the initiation of insulin therapy. It also poses considerable challenges when treatment is intensified. Addressing insulin-related weight gain is highly relevant to the prevention of metabolic and cardiovascular consequences in this high-risk population with type 2 diabetes. In addition to lifestyle changes (eg, diet and exercise) and available medical interventions to minimize the risk of weight gain with insulin treatment, familiarity with the weight gain patterns of different insulins may help deal with this problem. The use of basal insulin analogs may offer advantages over conventional human insulin preparations in terms of more physiologic time-action profiles, reduced risk of hypoglycemia, and reduced weight gain.

Improvement in peripheral glucose uptake after gastric bypass surgery is observed only after substantial weight loss has occurred and correlates with the magnitude of weight lost

INTRODUCTION

Altered gut and pancreatic hormone secretion may bolster resolution of insulin resistance after Roux-en-Y gastric bypass (RYGB), but the independent effects of weight loss and hormonal secretion on peripheral glucose disposal are unknown.

METHODS

Two groups of nondiabetic morbidly obese patients were studied: RYGB followed by standardized caloric restriction (RYGB, n = 12) or caloric restriction alone (diet, n = 10). Metabolic evaluations (euglycemic-hyperinsulinemic clamp, meal tolerance test) were done at baseline and 14 days (both groups) and 6 months after RYGB.

RESULTS

At baseline, body composition, fasting insulin, and glucose and peripheral glucose disposal did not differ between groups. At 14 days, excess weight loss (EWL) was similar (RYGB, 12.7% vs. diet, 10.9%; p = 0.12), fasting insulin and glucose decreased to a similar extent, and RYGB subjects had altered postmeal patterns of gut and pancreatic hormone secretion. However, peripheral glucose uptake (M value) was unchanged in both groups. Six months after RYGB, EWL was 49.7%. The changes in fasting glucose and insulin levels and gut hormone secretion persisted. M values improved significantly, and changes in M values correlated with the % EWL (r = 0.68, p = 0.02).

CONCLUSIONS

Improvement in peripheral glucose uptake following RYGB was observed only after substantial weight loss had occurred and correlated with the magnitude of weight lost.

Feasibility of a supervised inpatient low-calorie diet program for massive weight loss prior to RYGB in superobese patients

BACKGROUND

This study was undertaken to determine the feasibility of an inpatient low-calorie program for a substantial decrease of preoperative weight (>10 points in BMI) in superobese patients.

METHODS

Five patients were hospitalized for an average of 11 weeks and were placed on a low-calorie liquid diet (<900 kcal/day) and an exercise program. Following a drop of ten points in BMI, they underwent a Roux-en-Y gastric bypass (RYGB). Hemoglobin A1c and lipid profiles were obtained at the beginning of the diet, prior to surgery and at the last follow-up appointment. Our results were compared to the National Surgical Quality Improvement Program (NSQIP) database, which included 1,046 bariatric operations performed at VA centers between October 1999 and August 2007.

RESULTS

All five patients were massively obese men (body mass index (BMI) = 64.3 +/- 2.1 kg/m(2); 54.7 +/- 2.6 years old; four of five were white) with multiple comorbid conditions, which placed them in a substantially higher risk for bariatric surgery. Of the four diabetic patients, two were insulin dependent. There was an average decrease in BMI by 12.7 points (85.8 +/- 6.0 lb) during the preoperative diet period (11 weeks). All patients underwent RYGB without complications. This cohort of patients further decreased their BMI by 10.6 points (88.4 +/- 29.4 lb) following surgical intervention. The total combined preoperative and postoperative excess body weight loss was 89% (10.6-month average follow-up). Sleep apnea resolved following gastric bypass but did not improve during the preoperative weight loss period. Hypertension, osteoarthritis, and dyslipidemia all improved following surgical intervention. Hemoglobin A1c decreased by 1.9% during diet-induced weight loss with no further improvement being noted after surgery. The two insulin-dependent diabetic patients discontinued insulin therapy following surgery. The NSQIP database contained 77 patients with similar characteristics to our cohort of patients. The 30-day mortality for this cohort of patients was 3.9% with a complication rate of 33.8%.

CONCLUSIONS

Massive preoperative weight loss is possible to achieve with a liquid protein diet in superobese patients greatly facilitating gastric bypass surgery in an otherwise high-risk patient population.

Interpreting weight losses from lifestyle modification trials: using categorical data

Although studies in obese subjects using weight loss medications typically report mean and categorical weight loss, results from diet and exercise intervention trials typically only report mean weight change from baseline along with a level of significance. These data alone do not give clinicians or administrators the data needed to determine the probability that an individual will achieve clinically relevant weight loss. Thus, it is difficult to decide which patients, employees or health plan enrollee would benefit from the type and level of support used in a clinical trial. Our goal was to assess what fraction of subjects enrolled in lifestyle modification interventions achieved clinically significant weight loss. Thus, we requested categorical weight loss data from several investigators who had published results from studies involving either a high- or low-intensity lifestyle modification intervention arm. These categorical data indicate that a substantial fraction of subjects in each lifestyle modification intervention achieved clinically meaningful weight loss, even when the average weight loss is modest.

[Is laparoscopic gastric bypass a dangerous procedure during the early phase of the learning curve? A prospective study of the first 50 cases]

BACKGROUND

Among the various bariatric procedures, laparoscopic Roux-en-Y gastric bypass (LRYGBP) is widely considered to be the gold standard. However, a majority of bariatric surgeons in France do not perform LFYGBP, perhaps because of its reputation as a technically demanding procedure with a long learning curve. This study evaluates the outcomes and the learning curve for the first 50 LFYGBP performed by one surgeon in a French non-university hospital.

MATERIAL AND METHOD

Between April 2007 and February 2009, we performed our first 50 cases of LRYGBP. Surgical outcomes and the learning curve were measured by prospective criteria including length of stay, operative time, complications, percentage weight loss and reduction of obesity-related co-morbidities.

RESULTS

The mean patient age was 41.8+/-9.8 years. The mean BMI was 47.7+/-7.1 kg/m(2). The mean operative time was 146+/-51 minutes and the mean hospital stay was 5.3+/-1.4 days. Three cases (6%) were converted to open surgery. Early complications occurred in 4% and late complications occurred in 6%. The average follow-up was 6.3+/-1.3 months. Overall excess weight loss was 39.5, 50, 62, and 63% at 3, 6, 9, and 12 months.

CONCLUSION

LRYGBP can be performed with acceptable morbidity and short-term results, even during the early phase of a surgeon's learning curve. It is a feasible procedure for bariatric surgeons with previous experience in gastric banding.

Minireview: Hormonal and metabolic mechanisms of diabetes remission after gastrointestinal surgery

Bariatric surgery is the most effective available treatment for obesity. The most frequently performed operation, Roux-en-Y gastric bypass (RYGB), causes profound weight loss and ameliorates obesity-related comorbid conditions, especially type 2 diabetes mellitus (T2DM). Approximately 84% of diabetic patients experience complete remission of T2DM after undergoing RYGB, often before significant weight reduction. The rapid time course and disproportional degree of T2DM improvement after RYGB compared with equivalent weight loss from other interventions suggest surgery-specific, weight-independent effects on glucose homeostasis. Potential mechanisms underlying the direct antidiabetic impact of RYGB include enhanced nutrient stimulation of lower intestinal hormones (e.g. glucagon-like peptide-1), altered physiology from excluding ingested nutrients from the upper intestine, compromised ghrelin secretion, modulations of intestinal nutrient sensing and regulation of insulin sensitivity, and other changes yet to be fully characterized. Research aimed at determining the relative importance of these effects and identifying additional mechanisms promises not only to improve surgical design but also to identify novel targets for diabetes medications.

Surgery for nonobese type 2 diabetic patients: an interventional study with duodenal-jejunal exclusion

BACKGROUND

A 24-week interventional prospective trial was performed to compare the benefits of open duodenal-jejunal exclusion surgery (GJB) with a matched control group on standard medical care.

METHODS

One-hundred eighty patients were screened for the surgical approach. Twelve patients accepted to be operated and presented the full eligibility criteria for surgery that includes overweight BMI (25-29.9 kg/m2), T2DM diagnosis for less than 15 years, insulin-treated patients, no history of major complications, preserved beta-cell function, and absence of autoimmunity. A matched control group (CG) of patients whom refused surgical treatment was placed to receive standard care. Patients had age of 50 (5) years, time of diagnosis 9 years (range, 3 to 15 years), time of insulin usage 6 months (range, 3 to 48 months), fasting glucose (FG), 9.8 (2.5) mg/dL, and glycated hemoglobin (A1C) 8.90 (2.12)%.

RESULTS

At 24 weeks after surgery, patients experienced greater reductions on FG (14% vs. 7% on CG), A1C (from 8.78 to 7.84 in GJB-p<0.01 and 8.93 to 8.71 in CG; p<0.05 between groups) and reductions on average daily insulin requirement (93% vs. 29%, p<0.01). Ten patients stopped insulin usage in GJB but they remain taking oral medications. No differences were observed in both groups regarding BMI, body distribution and composition, blood pressure, and lipids.

CONCLUSIONS

In conclusion, duodenal-jejunal exclusion was an effective treatment for nonobese T2DM subjects. GJB was superior to standard care in achieving better glycemic control along with reduction in insulin requirements.

Cost-efficacy of surgically induced weight loss for the management of type 2 diabetes: a randomized controlled trial

OBJECTIVE

To determine the within-trial cost-efficacy of surgical therapy relative to conventional therapy for achieving remission of recently diagnosed type 2 diabetes in class I and II obese patients.

RESEARCH DESIGN AND METHODS

Efficacy results were derived from a 2-year randomized controlled trial. A health sector perspective was adopted, and within-trial intervention costs included gastric banding surgery, mitigation of complications, outpatient medical consultations, medical investigations, pathology, weight loss therapies, and medication. Resource use was measured based on data drawn from a trial database and patient medical records and valued based on private hospital costs and government schedules in 2006 Australian dollars (AUD). An incremental cost-effectiveness analysis was undertaken.

RESULTS

Mean 2-year intervention costs per patient were 13,400 AUD for surgical therapy and 3,400 AUD for conventional therapy, with laparoscopic adjustable gastric band (LAGB) surgery accounting for 85% of the difference. Outpatient medical consultation costs were three times higher for surgical patients, whereas medication costs were 1.5 times higher for conventional patients. The cost differences were primarily in the first 6 months of the trial. Relative to conventional therapy, the incremental cost-effectiveness ratio for surgical therapy was 16,600 AUD per case of diabetes remitted (currency exchange: 1 AUD = 0.74 USD).

CONCLUSIONS

Surgical therapy appears to be a cost-effective option for managing type 2 diabetes in class I and II obese patients.

The stomach in diabetes: from villain to ally

The stomach is commonly the source of chronic digestive symptoms in patients with diabetes mellitus; erratic stomach emptying may result in poor glycemic control. On the other hand, medications that mimic or enhance the function of the endogenous incretins retard gastric emptying to enhance glycemic control. In patients with obesity and type 2 diabetes, bariatric procedures alter food intake and weight; however, effects on glycemic control precede and are out of proportion with the degree of weight loss. The mechanisms responsible for the improved glycemic control after bariatric surgery are the subject of ongoing research, and include increased circulating incretins stimulated by the delivery of nutrients to the intestine, contributing to weight loss and independently to glycemic control. The stomach is not always a villain, but is an ally in patients with type 2 diabetes.