Moderate effect of duodenal-jejunal bypass surgery on glucose homeostasis in patients with type 2 diabetes

Duodenal-jejunal bypass surgery activates eNOS and enhances antioxidant system by activating AMPK pathway to improve heart oxidative stress in diabetic cardiomyopathy rats

BACKGROUND

Diabetic cardiomyopathy is a serious complication of obesity with type 2 diabetes and is a major cause of mortality. Metabolic surgery, such as duodenal-jejunal bypass (DJB), can effectively improve diabetic cardiomyopathy; however, the underlying mechanisms remain elusive. Oxidative stress is one of the pivotal mechanisms of diabetic cardiomyopathy. Our objective was to investigate the effect and potential mechanisms of DJB on oxidative stress in the heart of diabetic cardiomyopathy rats.

METHODS

High-fat diet combined with intraperitoneal injection of streptozotocin was used to establish diabetic cardiomyopathy rats. DJB was performed on diabetic cardiomyopathy rats, and high glucose and palmitate were used to simulate diabetic cardiomyopathy in H9C2 cells in vitro. Sera from different groups of rats were used for experiments in vivo and in vitro.

RESULTS

DJB effectively improved oxidative stress and activated the adenosine monophosphate (AMP)-activated protein kinase (AMPK) pathway to increase endothelial nitric oxide synthase (eNOS) phosphorylation level and the expression of antioxidative system-related proteins and genes in the heart of diabetic cardiomyopathy rats. AMPK agonists and serum from DJB rats activated the AMPK pathway to increase eNOS phosphorylation level and the expression of antioxidative system-related proteins and genes and decreased the content of reactive oxygen species in H9C2 cells, but this improvement was almost eliminated by the addition of AMPK inhibitors.

CONCLUSIONS

DJB activates eNOS and enhances the antioxidant system by activating the AMPK pathway-and not solely by improving blood glucose-to improve oxidative stress in the heart of diabetic cardiomyopathy rats.

Enteroendocrine Reprogramming by Altered Epithelial-Mesenchymal Crosstalk in Metabolic Surgery

Metabolic surgery is an effective treatment option for type 2 diabetes. However, the therapeutic scope has been limited by unexpected inconsistent outcomes. This study aims to overcome these obstacles by determining fundamental mechanisms from a novel perspective by analyzing and comparing the surgical anatomy, clinical characteristics, and outcomes of metabolic surgery, including duodenal-jejunal bypass, Roux-en-Y gastric bypass, biliopancreatic diversion, one anastomosis gastric bypass, and their modified procedures, predominantly focusing on nonobese patients to mitigate confounding effects from overweighted type 2 diabetes. Regional epithelial cell growth and unique villus formation along the anterior-posterior axis of the small intestine depend on crosstalk between the epithelium and the underlying mesenchyme. Due to altered crosstalk between the epithelium and the opposite mesenchyme at the anastomotic site, the enteroendocrine lineage of the distal intestine is replaced by the proximal epithelium after the bypass procedure. Subsequent intestinal compensatory proliferation accelerates the expansion of the replaced epithelium, including enteroendocrine cells. The primary reasons for unsatisfactory results are incomplete duodenal exclusion and insufficient biliopancreatic limb length. We anticipate that this novel mechanism will have a significant impact on metabolic surgery outcomes and provide valuable insight into optimizing its effectiveness in type 2 diabetes.

Updates in metabolic bariatric endoscopy

Obesity and its associated comorbid conditions have been increasing globally. Endoscopic bariatric and metabolic therapies (EBMTs) were initially designed to replicate bariatric surgery physiology for those who are not or choose not to be surgical candidates. Now, newer procedures target the complicated pathophysiology underlying obesity and its comorbidities. EBMT has been categorized based on its therapeutic target (stomach or small intestine), but innovations have expanded to include extraintestinal organs including the pancreas. Gastric EBMTs, namely space-occupying balloons, gastroplasty with suturing or plication, and aspiration therapy, are primarily used for weight loss. Small bowel EBMTs are designed to cause malabsorption, epithelial endocrine remodeling, and other changes to intestinal physiology to ultimately improve the metabolic comorbidities of obesity rather than induce weight loss alone. These include duodenal mucosal resurfacing, endoluminal bypass sleeves, and incisionless anastomosis systems. Extraluminal or pancreatic EBMT is aimed to restore the production of normal pancreatic proteins that are involved in the progression of type 2 diabetes. This review discusses the current and new technologies of metabolic bariatric endoscopy, their pros and cons, and areas for future research.

Worksite-based intensive lifestyle therapy has profound cardiometabolic benefits in people with obesity and type 2 diabetes

Lifestyle therapy (energy restriction and exercise) is the cornerstone of therapy for people with type 2 diabetes (T2D) but is difficult to implement. We conducted an 8-month randomized controlled trial in persons with obesity and T2D (17 women and 1 man) to determine the therapeutic effects and potential mechanisms of intensive lifestyle therapy on cardiometabolic function. Intensive lifestyle therapy was conducted at the worksite to enhance compliance and resulted in marked (17%) weight loss and beneficial changes in body fat mass, intrahepatic triglyceride content, cardiorespiratory fitness, muscle strength, glycemic control, β cell function, and multi-organ insulin sensitivity, which were associated with changes in muscle NAD+ biosynthesis, sirtuin signaling, and mitochondrial function and in adipose tissue remodeling. These findings demonstrate that intensive lifestyle therapy provided at the worksite has profound therapeutic clinical and physiological effects in people with T2D, which are likely mediated by specific alterations in skeletal muscle and adipose tissue biology.

Duodenal-jejunal bypass increases intraduodenal bile acids and upregulates duodenal SIRT1 expression in high-fat diet and streptozotocin-induced diabetic rats

BACKGROUND

The mechanisms underlying diabetes remission after duodenal-jejunal bypass (DJB) remain elusive. In DJB surgery, the duodenum is excluded. However, the duodenum has emerged as an important regulator of glucose homeostasis, and elevated duodenal SIRT1 leads to improved hepatic insulin sensitivity. After DJB, bile acids (BAs) in the duodenum are not mixed and diluted by the ingested food. And activation of BA receptors promotes SIRT1 expression in many tissues. We hypothesized that BA-mediated upregulation of SIRT1 may contribute to diabetic control after DJB.

AIM

To investigate the surgical effects of DJB on duodenal SIRT1 expression and uncover the potential crosslinks between BAs and SIRT1.

METHODS

Twenty diabetic rats were randomly allocated to the sham (n = 10) and DJB (n = 10) groups. Body weight, food intake, fasting blood glucose (FBG), serum and intraduodenal total BA (TBA) levels were measured accordingly. Oral glucose tolerance test (OGTT) and intraperitoneal pyruvate tolerance test (ipPTT) were performed to evaluate the effects of surgeries on systemic glucose disposal and hepatic gluconeogenesis. The key genes of BA signaling pathway in the duodenal mucosa, including farnesoid X receptor (FXR), small heterodimer partner (SHP), and Takeda G-protein-coupled receptor 5 (TGR5) were evaluated by real-time quantitative polymerase chain reaction 8 wk postoperatively. The duodenal SIRT1, AMPK, and phosphorylated AMPK (p-AMPK) levels were evaluated by western blotting. Rat small intestine epithelial IEC-6 cells were treated with GW4064 and INT-777 to verify the effects of BAs on SIRT1 expression in enterocytes.

RESULTS

The DJB group exhibited body weight and food intake comparable to those of the sham group at all postoperative time points. The FBG level and area under the curve for the OGTT and ipPTT were significantly lower in the DJB group. The DJB group exhibited higher fasting and postprandial serum TBA levels than the sham group at both 2 and 8 wk postoperatively. At 8 wk after surgery, the DJB group showed higher intraluminal TBA concentration, upregulated mRNA expression of FXR and SHP, and elevated protein expression of SIRT1 and p-AMPK in the descending and horizontal segments of the duodenum. Activation of FXR and TGR5 receptors by GW4064 and INT-777 increased the mRNA and protein expression of SIRT1 and promoted the phosphorylation of AMPK in IEC-6 cells.

CONCLUSION

DJB elevates intraduodenal BA levels and activates the duodenal BA signaling pathway, which may upregulate duodenal SIRT1 and further contribute to improved glucose homeostasis after DJB.

Mechanisms of action of duodenal mucosal resurfacing in insulin resistant women with polycystic ovary syndrome

BACKGROUND

Duodenal mucosal resurfacing (DMR) is a novel day-case endoscopic intervention which results in weight loss-independent reductions in HbA1c in patient with type 2 diabetes mellitus (T2DM). We hypothesized that DMR works by increasing insulin sensitivity and we aimed to investigate the mechanism of action of DMR through longitudinal metabolic phenotyping in humans.

METHODS

Thirty-two insulin-resistant women with polycystic ovary syndrome (PCOS) and obesity were randomised in a double-blinded manner to DMR or sham endoscopy. They underwent measurements of insulin sensitivity using euglycaemic hyperinsulinaemic clamps, insulin secretion using oral glucose tolerance tests and reproductive function using weekly reproductive hormone profiles and ovarian ultrasonography for 6 months post-intervention.

RESULTS

A small increase in total body insulin sensitivity measured by the clamp was observed in both groups at week 12. An increase in insulin sensitivity, as measured by HOMA-IR, was observed in both groups at week 24. There was an increase in the number of menses (median 2 DMR, 0.5 sham). There were no significant differences between the two groups in these outcomes or insulin secretion.

CONCLUSIONS

These findings suggest that DMR does not work by increasing insulin sensitivity in euglycaemic, insulin resistant women with PCOS. The procedure may exert its effects only in the context of hyperglycaemia or pathologically hyperplastic, insulin-desensitised duodenal mucosa.

The Role of Gut Microbiota in Duodenal-Jejunal Bypass Surgery-Induced Improvement of Hepatic Steatosis in HFD-Fed Rats

Bariatric surgery including duodenal-jejunal bypass surgery (DJB) improves insulin sensitivity and reduces obesity-associated inflammation. However, the underlying mechanism for such an improvement is still incompletely understood. Our objective was to investigate the role of the gut microbiota in DJB-associated improvement of hepatic steatosis in high fat diet (HFD)-fed rats. To study this, hepatic steatosis was induced in male adult Sprague-Dawley rats by feeding them with a 60% HFD. At 8 weeks after HFD feeding, the rats were subjected to either DJB or sham operation. HFD was resumed 1 week after the surgery for 3 more weeks. In additional groups of animals, feces were collected from HFD-DJB rats at 2 weeks after DJB. These feces were then transplanted to HFD-fed rats without DJB at 8 weeks after HFD feeding. Hepatic steatosis and fecal microbiota were analyzed at 4 weeks after surgery or fecal transplantation. Our results showed that DJB alleviated hepatic steatosis in HFD-fed rats. Fecal microbiota analysis showed that HFD-fed and standard diet-fed rats clustered differently. DJB induced substantial compositional changes in the gut microbiota. The fecal microbiota of HFD-fed rats received fecal transplant from DJB rats overlapped with that of HFD-DJB rats. Treatment of rats with HFD-induced liver lesions by fecal transplant from DJB-operated HFD-fed rats also attenuated hepatic steatosis. Thus, alterations in the gut microbiota after DJB surgery are sufficient to attenuate hepatic steatosis in HFD-fed rats. Targeting the gut microbiota could be a promising approach for preventing or treating human NAFLD.

Effects of Diet versus Gastric Bypass on Metabolic Function in Diabetes

BACKGROUND

Some studies have suggested that in people with type 2 diabetes, Roux-en-Y gastric bypass has therapeutic effects on metabolic function that are independent of weight loss.

METHODS

We evaluated metabolic regulators of glucose homeostasis before and after matched (approximately 18%) weight loss induced by gastric bypass (surgery group) or diet alone (diet group) in 22 patients with obesity and diabetes. The primary outcome was the change in hepatic insulin sensitivity, assessed by infusion of insulin at low rates (stages 1 and 2 of a 3-stage hyperinsulinemic euglycemic pancreatic clamp). Secondary outcomes were changes in muscle insulin sensitivity, beta-cell function, and 24-hour plasma glucose and insulin profiles.

RESULTS

Weight loss was associated with increases in mean suppression of glucose production from baseline, by 7.04 μmol per kilogram of fat-free mass per minute (95% confidence interval [CI], 4.74 to 9.33) in the diet group and by 7.02 μmol per kilogram of fat-free mass per minute (95% CI, 3.21 to 10.84) in the surgery group during clamp stage 1, and by 5.39 (95% CI, 2.44 to 8.34) and 5.37 (95% CI, 2.41 to 8.33) μmol per kilogram of fat-free mass per minute in the two groups, respectively, during clamp stage 2; there were no significant differences between the groups. Weight loss was associated with increased insulin-stimulated glucose disposal, from 30.5±15.9 to 61.6±13.0 μmol per kilogram of fat-free mass per minute in the diet group and from 29.4±12.6 to 54.5±10.4 μmol per kilogram of fat-free mass per minute in the surgery group; there was no significant difference between the groups. Weight loss increased beta-cell function (insulin secretion relative to insulin sensitivity) by 1.83 units (95% CI, 1.22 to 2.44) in the diet group and by 1.11 units (95% CI, 0.08 to 2.15) in the surgery group, with no significant difference between the groups, and it decreased the areas under the curve for 24-hour plasma glucose and insulin levels in both groups, with no significant difference between the groups. No major complications occurred in either group.

CONCLUSIONS

In this study involving patients with obesity and type 2 diabetes, the metabolic benefits of gastric bypass surgery and diet were similar and were apparently related to weight loss itself, with no evident clinically important effects independent of weight loss. (Funded by the National Institutes of Health and others; ClinicalTrials.gov number, NCT02207777.).

Metabolic Outcomes of Surgery for Non-Obese Type 2 Diabetes

The most plausible contributing factor to non-obese type 2 diabetes may be imbalanced incretin release from the intestinal epithelium in response to nutrients. Rerouting intestinal continuity through bypass surgery to modulate incretin release is therefore a reasonable treatment. We believe that a major determinant of metabolic outcomes is entire duodenal exclusion without leaving any duodenal epithelium and exclusion of sufficient length of jejunum. More importantly, the procedure should be implemented with safety and without sequelae. To achieve this, we invented a novel procedure with acceptable surgical safety and excellent and durable metabolic outcomes. Post-surgical intestinal adaptation should be considered to achieve successful outcomes.

Metabolic endoscopy by duodenal mucosal resurfacing: expert review with critical appraisal of the current technique and results

INTRODUCTION

Duodenal mucosal resurfacing (DMR) is an endoscopic procedure for type 2 diabetes (T2D) consisting of circumferential hydrothermal ablation of the duodenal mucosa.

AREAS COVERED

A review was conducted on the reports available up to March-2020. On a total of 79 patients, DMR induced a significant mean HbA1c, FPG and HOMA-IR reduction at 6 months (0.9 ± 0.2%, 1.7 ± 0.5 mmol/L and 2.9 ± 1.1 mUI/L respectively - P < 0.001). DMR metabolic efficacy directly correlates with the length of the ablated mucosa (mean 3 months HbA1c reduction 1.2% vs 2.5% after short and long ablation respectively - P < 0.05), while it is independent of weight-loss. Severe AEs were registered in 3.7% of the cases.

EXPERT OPINION

DMR plays a promising role in metabolic impairment improvement inducing a morpho-functional duodenal alteration not necessarily depending on weight-loss. Technical-functional improvements of the device and appropriate training aimed at its correct use are needed to lower the rate of severe AEs and technical failure. The current role of DMR needs to be clarified, but it might be proposed for poorly controlled T2D in accurately selected patients. Evidence on DMR is still scanty and further research is mandatory to standardize the endoscopic technique and its indications.

Evaluating the safety of bariatric surgery for weight loss in class I obesity: A propensity-matched analysis of North American data

BACKGROUND

Bariatric surgery is an effective treatment for severe obesity. However, there has been an evolving role for bariatric surgery as a primary treatment in the management of class I obesity.

OBJECTIVES

We aimed to assess the safety of surgery by directly comparing surgical outcomes of laparoscopic sleeve gastrectomy (LSG) and laparoscopic Roux-en-Y gastric bypass (LRYGB) in class I obesity (body mass index [BMI] 30-35 kg/m²) with those with class II obesity (BMI 35-40 kg/m²) and higher (BMI >40 kg/m²) using an analysis of a large-scale matched-patient cohort analysis.

SETTING

Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program database, United States and Canada.

METHODS

We performed a retrospective analysis using the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program database, which collects patient information from >790 bariatric surgery centers in North America. Patients included in our analysis underwent surgery in the years 2015 and 2016 and had either LRYGB or LSG for weight loss.

RESULTS

Initial analysis included 274,091 patients. Propensity-matching resulted in 9104 patients for analysis in each of the class I and class II and higher groups. The overall major complication rate between the 2 matched groups was 3.9% for class I and 3.5% for class II and higher (P = .11). We did not find that class I obesity was associated with an increased risk of 30-day complication or death.

CONCLUSIONS

In our analysis of propensity-matched patients undergoing LSG and LRYGB for weight loss, class I obesity did not have statistically higher risk of postoperative complication rates compared with class II and higher.

Improved FGF21 Sensitivity and Restored FGF21 Signaling Pathway in High-Fat Diet/Streptozotocin-Induced Diabetic Rats After Duodenal-Jejunal Bypass and Sleeve Gastrectomy

Objective: Bariatric surgery can profoundly improve glucose and lipid metabolism in diabetic rats. Fibroblast growth factor 21 (FGF21) is an important hormone with multiple metabolic beneficial effects. Alteration in serum FGF21 level after bariatric surgery has been reported with conflicting results. Here, we investigated the effect of bariatric surgeries on FGF21 expression and sensitivity. Methods: We performed duodenal-jejunal bypass (DJB), sleeve gastrectomy (SG) and sham surgery in diabetic rats induced by high fat diet and streptozotocin. Metabolic parameters, including body weight, food intake, glucose tolerance, and lipid profiles, were monitored. FGF21 levels in both serum and liver were measured after surgery. FGF21 signaling pathway including FGF receptor 1 (FGFR1), β-klotho (KLB), and phosphorylated extracellular signal-regulated kinase 1/2 (ERK1/2) was detected in the liver and white adipose tissue (WAT). We also determined FGF21 sensitivity post-operatively by acute recombinant human FGF21 injection. Oral glucose tolerance test (OGTT) and insulin tolerance test (ITT) were conducted immediately after FGF21 injection. Serum triglyceride (TG) and non-esterified fatty acid (NEFA) were measured and the mRNA levels of early growth response 1 (Egr1) and c-Fos in the liver and WAT were detected after FGF21 injection. Results: Improvements in glucose tolerance, insulin sensitivity, and lipid profiles were observed after bariatric surgeries along with ameliorated lipid metabolism in the liver and WAT. Serum and hepatic FGF21 levels decreased in both DJB and SG groups. FGFR1 and phosphorylated ERK1/2 levels increased in both DJB and SG groups 8 weeks after surgery. The expression of KLB was downregulated only in the WAT after DJB and SG. Significant alteration of OGTT and ITT were observed after acute FGF21 administration in DJB and SG groups. Serum TG and NEFA in DJB and SG groups also decreased after FGF21 administration. And increased mRNA levels of Egr1 and c-Fos were detected in the liver and WAT after DJB and SG surgeries. Conclusions: DJB and SG surgeries can downregulate hepatic expression of FGF21, restore FGF21 signaling pathway and improve FGF21 sensitivity in high-fat diet/streptozotocin-induced diabetic rats.

Bile acid profiles within the enterohepatic circulation in a diabetic rat model after bariatric surgeries

Bile acids (BAs), which are synthesized in the liver and cycled in the enterohepatic circulation, have been recognized as signaling molecules by activating their receptors in the intestine and liver. Serum taurine-conjugated BAs have been shown to be elevated after bariatric surgeries although the postoperative BA profiles within the enterohepatic circulation have not been investigated. Clarification of these profiles could help explain the mechanisms by which bariatric surgery leads to BA profile alterations and subsequent metabolic effects. We performed duodenal-jejunal bypass (DJB), sleeve gastrectomy (SG), and sham procedures in an obese diabetic rat model induced by high-fat diet and streptozotocin. The weight loss and antidiabetic effects were evaluated postsurgery. BA profiles in the systemic serum and within the enterohepatic circulation were analyzed, together with the expression of related BA transporters and enzymes at week 12 after surgery. Compared with sham, SG induced sustained weight loss, and both DJB and SG significantly improved glucose tolerance and insulin sensitivity with enhanced glucagon-like peptide 1 secretion. Similar to changes in the serum, BAs, especially taurine-conjugated species, were also elevated in the enterohepatic circulation (bile and portal vein) after DJB and SG. In addition, the expression of key BA transporters and conjugational enzymes was elevated postoperatively, whereas the enzymes responsible for BA synthesis were decreased. In conclusion, DJB and SG elevated BA levels in the systemic serum and enterohepatic circulation, especially taurine-conjugated species, which likely indicates increased ileal reabsorption and hepatic conjugation rather than synthesis. NEW & NOTEWORTHY Bile acids (BAs) have been implicated as potential mediators of the weight-independent effects of bariatric surgery. For the first time, we discovered that duodenal-jejunal bypass and sleeve gastrectomy elevated BAs, particularly the taurine-conjugated species in the enterohepatic circulation, likely through the promotion of ileal reabsorption and hepatic conjugation rather than BA synthesis. These findings will improve our understanding of BA metabolism after bariatric surgery and their subsequent metabolic effects.

Endoscopic Duodenal Mucosal Resurfacing for the Treatment of Type 2 Diabetes

Type 2 diabetes is a pandemic disease with an incidence that has risen steadily over recent decades. Experimental evidence in animals has demonstrated that intestinal bypass surgery of the upper small intestine, particularly the duodenum, has an important role in glucose homoeostasis. Furthermore, Roux-en-Y bypass performed as bariatric surgery has shown to correct hyperglycaemia from the first postoperative days in obese diabetic patients. Therefore, on the basis of these considerations, duodenal mucosal resurfacing was studied in type 2 diabetes patients as a minimally invasive procedure that could offer an alternative treatment for these patients. Further studies, and particularly large controlled trials, are needed to determine the place of this procedure in the treatment of type 2 diabetes as well as other metabolic diseases such as non-alcoholic fatty liver disease/non-alcoholic steatohepatitis.

Surgery for Diabetes: Clinical and Mechanistic Aspects

According to the most recent publication by the Canadian Public Health Agency, obesity affects 25% of adults. In addition, there is a clear association between the recent rise in obesity and the increased prevalence of type 2 diabetes. Medical therapy for obesity has shown limited long-term effectiveness, and surgical treatment is now recognized by medical authorities as part of the armamentarium for the management of type 2 diabetes in severely obese patients. The current indications for obesity surgery and postoperative management are reviewed. The choice of surgery should balance expected benefits associated with weight loss (including remission rate of type 2 diabetes), side effects and the risks for early and long-term complications. Long-term outcomes of metabolic surgery for diabetes vary according to the type of surgery (ranging between 20% and 90% remission rates) and the underlying metabolic changes. Several controlled trials have been published in recent years confirming the superiority of metabolic surgery over medical treatment for the management of type 2 diabetes associated with severe obesity. Some of the known underlying mechanisms of action include a combination of caloric restriction, hormonal changes, decreased nutrient absorption and changes in bile acids, microbiota and incretins. Further research is needed to clarify the mechanistic changes associated with each surgical procedure and their respective long-term outcomes.

Duodenal-Jejunal Bypass Surgery Reverses Diabetic Phenotype and Reduces Obesity in db/db Mice

Type 2 diabetes mellitus (T2DM), a complex metabolic disorder typically accompanying weight gain, is associated with progressive β-cell failure and insulin resistance. Bariatric surgery ameliorates glucose tolerance and provides a near-perfect treatment. Duodenal-jejunal bypass (DJB) is an experimental procedure and has been studied in several rat models, but its influence in db/db mice, a transgenic model of T2DM, remains unclear. To investigate the effectiveness of DJB in db/db mice, we performed the surgery and evaluated metabolism improvement. Results showed that mice in DJB group weighed remarkably less than sham group two weeks after surgery. Compared to the preoperative level, postoperative fasting blood glucose (FBG) was dramatically reduced. Statistical analysis revealed that changes in body weight and FBG were significantly correlated. Besides, DJB surgery altered plasma insulin level with approximate 40% reduction. Thus, for the first time we proved that DJB can achieve rapid therapeutic effect in transgenic db/db mice with severe T2DM as well as obesity. In addition, decreased insulin level reflected better insulin sensitivity induced by DJB. In conclusion, our study demonstrates that DJB surgery may be a potentially effective way to treat obesity-associated T2DM.

Cross-Talk Between Bile Acids and Gastro-Intestinal and Thermogenic Hormones: Clues from Bariatric Surgery

Obesity is rapidly increasing and has reached epidemic features worldwide. It´s linked to insulin resistance, systemic low-grade inflammation and common pathogenic pathways with a number of comorbidities (including cancer), leading to high mortality rates. Besides change of lifestyles (diet and physical exercise) and pharmacological therapy, bariatric surgery is able to rapidly improve several metabolic and morphologic features associated with excessive fat storage, and currently represents an in vivo model to study the pathogenic mechanisms underlying obesity and obesity-related complications. Studies on obese subjects undergoing bariatric surgery find that the effects of surgery are not simply secondary to gastric mechanical restriction and malabsorption which induce body weight loss. In fact, some surgical procedures positively modify key pathways involving the intestine, bile acids, receptor signaling, gut microbiota, hormones and thermogenesis, leading to systemic metabolic changes. Furthermore, bariatric surgery represents a suitable model to evaluate the gene-environment interaction and some epigenetic mechanisms linking obesity and insulin resistance to metabolic diseases.

Diabetes-associated microbiota in fa/fa rats is modified by Roux-en-Y gastric bypass

Roux-en-Y gastric bypass (RYGB) and duodenal jejunal bypass (DJB), two different forms of bariatric surgery, are associated with improved glucose tolerance, but it is not clear whether the gut microbiota contributes to this effect. Here we used fa/fa rats as a model of impaired glucose tolerance to investigate whether (i) the microbiota varies between fa/fa and nondiabetic fa/+ rats; (ii) the microbiota of fa/fa rats is affected by RYGB and/or DJB; and (iii) surgically induced microbiota alterations contribute to glucose metabolism. We observed a profound expansion of Firmicutes (specifically, Lactobacillus animalis and Lactobacillus reuteri) in the small intestine of diabetic fa/fa compared with nondiabetic fa/+ rats. RYGB-, but not DJB-, treated fa/fa rats exhibited greater microbiota diversity in the ileum and lower L. animalis and L. reuteri abundance compared with sham-operated fa/fa rats in all intestinal segments, and their microbiota composition resembled that of unoperated fa/+ rats. To investigate the functional role of RYGB-associated microbiota alterations, we transferred microbiota from sham- and RYGB-treated fa/fa rats to germ-free mice. The metabolic phenotype of RYGB-treated rats was not transferred by the transplant of ileal microbiota. In contrast, postprandial peak glucose levels were lower in mice that received cecal microbiota from RYGB- versus sham-operated rats. Thus, diabetes-associated microbiota alterations in fa/fa rats can be modified by RYGB, and modifications in the cecal microbiota may partially contribute to improved glucose tolerance after RYGB.

Endoscopic Bariatric and Metabolic Therapies: New and Emerging Technologies

Endoscopic bariatric and metabolic therapies (EBMT) are a new addition to the treatment arsenal for obesity. These include devices that are placed or removed via flexible endoscopy, and procedures that utilize instruments that require flexible endoscopy for the indications of weight loss or treatment of glucose intolerance (from pre-diabetes to diabetes). The EBMTs are generally divided into gastric and small bowel categories, and although individual EBMTs may have unique mechanisms of action, similar themes in proposed mechanism of action are seen in the gastric and small bowel EBMTs, respectively. In this review we will describe the therapies approved for use in the United States or currently in the process of obtaining approval for use in the United States. We will discuss potential mechanisms of action and examine safety and efficacy data.

Endoscopic Duodenal Mucosal Resurfacing for the Treatment of Type 2 Diabetes: 6-Month Interim Analysis From the First-in-Human Proof-of-Concept Study

OBJECTIVE

To assess procedural safety and glycemic indices at 6 months in a first-in-human study of duodenal mucosal resurfacing (DMR), a novel, minimally invasive, upper endoscopic procedure involving hydrothermal ablation of the duodenal mucosa, in patients with type 2 diabetes and HbA_1c ≥7.5% (58 mmol/mol) on one or more oral antidiabetic agents.

RESEARCH DESIGN AND METHODS

Using novel balloon catheters, DMR was conducted on varying lengths of duodenum in anesthetized patients at a single medical center.

RESULTS

A total of 39 patients with type 2 diabetes (screening HbA_1c 9.5% [80 mmol/mol]; BMI 31 kg/m²) were treated and included in the interim efficacy analysis: 28 had a long duodenal segment ablated (LS; ∼9.3 cm treated) and 11 had a short segment ablated (SS; ∼3.4 cm treated). Overall, DMR was well tolerated with minimal gastrointestinal symptoms postprocedure. Three patients experienced duodenal stenosis treated successfully by balloon dilation. HbA_1c was reduced by 1.2% at 6 months in the full cohort (P < 0.001). More potent glycemic effects were observed among the LS cohort, who experienced a 2.5% reduction in mean HbA_1c at 3 months postprocedure vs. 1.2% in the SS group (P < 0.05) and a 1.4% reduction at 6 months vs. 0.7% in the SS group (P = 0.3). This occurred despite net medication reductions in the LS cohort between 0 and 6 months. Among LS patients with a screening HbA_1c of 7.5-10% (58-86 mmol/mol) and on stable antidiabetic medications postprocedure, HbA_1c was reduced by 1.8% at 6 months (P < 0.01).

CONCLUSIONS

Single-procedure DMR elicits a clinically significant improvement in hyperglycemia in patients with type 2 diabetes in the short-term, with acceptable safety and tolerability. Long-term safety, efficacy, and durability and possible mechanisms of action require further investigation.

Surgical cure for type 2 diabetes by foregut or hindgut operations: a myth or reality? A systematic review

BACKGROUND

Bariatric surgery results in remission of type 2 diabetes mellitus in a significant proportion of patients. Animal research has proposed the foregut and hindgut hypotheses as possible mechanisms of remission of T2DM independent of weight loss. These hypotheses have formed the basis of investigational procedures designed to treat T2DM in non-obese (in addition to obese) patients. The aim of this study was to review the procedures that utilise the foregut and hindgut hypotheses to treat T2DM in humans.

METHODS

A systematic review was conducted to identify the investigational procedures performed in humans that are based on the foregut and hindgut hypotheses and then to assess their outcomes.

RESULTS

Twenty-four studies reported novel procedures to treat T2DM in humans; only ten utilised glycated haemoglobin A1c (HbA1c) in their definition of remission. Reported remission rates were 20-40 % for duodenal-jejunal bypass (DJB), 73-93 % for duodenal-jejunal bypass with sleeve gastrectomy (DJB-SG), 62.5-100 % for duodenal-jejunal bypass sleeve (DJBS) and 47-95.7 % for ileal interposition with sleeve gastrectomy (II-SG). When using a predetermined level of HbA1c to define remission, the remission rates were lower (27, 63, 0 and 65 %) for DJB, DJB-SG, DJBS and II-SG.

CONCLUSIONS

The outcomes of the foregut- and hindgut-based procedures are not better than the outcomes of just one of their components, namely sleeve gastrectomy. The complexity of these procedures in addition to their comparable outcomes to a simpler operation questions their utility.

Roux-en Y gastric bypass is superior to duodeno-jejunal bypass in improving glycaemic control in Zucker diabetic fatty rats

BACKGROUND

Whilst weight loss results in many beneficial metabolic consequences, the immediate improvement in glycaemia after Roux-en-Y Gastric bypass (RYGB) remains intriguing. Duodenal jejunal bypass (DJB) induces similar glycaemic effects, while not affecting calorie intake or weight loss. We studied diabetic ZDF(fa/fa) rats to compare the effects of DJB and RYGB operations on glycaemia.

METHODS

Male ZDF(fa/fa) rats, aged 12 weeks underwent RYGB, DJB or sham operations. Unoperated ZDF(fa/fa) and ZDF(fa/+w)ere used as controls. Body weight, food intake, fasting glucose, insulin and gut hormones were measured at baseline and on postoperative days 2, 10 and 35. An oral glucose tolerance test (OGTT) was performed on days 12 and 26.

RESULTS

DJB had similar food intake and body weight to sham-operated and unoperated control ZDF(fa/fa) rats (p = NS), but had lower fasting glucose (p < 0.05). RYGB had lower food intake, body weight and fasting glucose compared to all groups (p < 0.001). DJB prevented the progressive decline in fasting insulin observed in the sham-operated or unoperated ZDF(fa/fa) rats, while RYGB with normalized glycaemia reduced the physiological requirement for raised fasting insulin.

CONCLUSIONS

Bypassing the proximal small bowel with the DJB has mild to moderate body weight independent effects on glucose homeostasis and preservation of fasting insulin levels in the medium term. These effects might be further amplified by the additional anatomical and physiological changes after RYGB.

Biliopancreatic diversion-duodenal switch: independent contributions of sleeve resection and duodenal exclusion

BACKGROUND

The choice of first-stage operation in bilio-pancreatic diversion with duodenal switch (BPD-DS) is controversial. There are no published long-term comparisons of one- and two-stage BPD-DS outcomes.

METHODS

During 2001-2009, among 1,762 patients scheduled for BPD-DS 48 had duodenal switch (DS) and 53 sleeve gastrectomy (SG) as first-stage procedures. We compared prospectively updated outcomes of 42 DS (100 % open) and 49 SG (88 % laparoscopic), 13 of whom completed their second stage, to a control group of 91 patients with open one-stage BPD-DS.

RESULTS

One-year mean percent excess weight loss (%EWL) was greater after SG than DS (47 ± 19 vs. 39 ± 13 SD; p = 0.01) with earlier nadir (16 ± 10 vs. 45 ± 30 months; p < 0.0001) but more rapid significant weight regain. After 5 years, %EWL was 12 ± 35 for 9 SG, 45 ± 19 for 30 DS (p < 0.0006), and 70 ± 18 for the first-stage BPD-DS (p < 0.0001). Weight loss was less after two- than one-stage procedures (p < 0.02). Comorbidities improved progressively between SG, DS and BPD-DS (p < 0.001 for trend). HbA1C decreased by 10, 19, and 31 %, respectively (p < 0.0001). Dyslipidemia was cured in 41, 82, and 100 %, respectively. Systolic and diastolic blood pressure decreased only after DS (12 %; p < 0.0002). Patient satisfaction was similar for SG and DS but greater after BPD-DS overall (p = 0.04).

CONCLUSIONS

SG and DS independently contribute to beneficial metabolic outcomes after BPD-DS. Long-term weight loss and correction of metabolic abnormalities were better after DS favoring its use as first stage in BPD-DS; one-stage BPD-DS outcomes were superior to two-staged.

Effect of Duodenal-Jejunal Bypass Surgery on Glycemic Control in Type 2 Diabetes: A Randomized Controlled Trial

OBJECTIVE

To determine whether upper gastrointestinal tract (UGI) bypass itself has beneficial effects on the factors involved in regulating glucose homeostasis in patients with type 2 diabetes (T2D).

METHODS

A 12-month randomized controlled trial was conducted in 17 overweight/obese subjects with T2D, who received standard medical care (SC, n = 7, BMI = 31.7 ± 3.5 kg/m(2) ) or duodenal-jejunal bypass surgery with minimal gastric resection (DJBm) (n = 10; BMI = 29.7 ± 1.9 kg/m(2)). A 5-h modified oral glucose tolerance test was performed at baseline and at 1, 6, and 12 months after surgery or starting SC.

RESULTS

Body weight decreased progressively after DJBm (7.9 ± 4.1%, 9.6 ± 4.2%, and 10.2 ± 4.3% at 1, 6, and 12 months, respectively) but remained stable in the SC group (P < 0.001). DJBm, but not SC, improved: (1) oral glucose tolerance (decreased 2-h glucose concentration, P = 0.039), (2) insulin sensitivity (decreased homeostasis model assessment of insulin resistance, P = 0.013), (3) early insulin response to a glucose load (increased insulinogenic index, P = 0.022), and (4) overall glycemic control (reduction in HbA1c with fewer diabetes medications).

CONCLUSIONS

DJBm causes moderate weight loss and improves metabolic function in T2D. However, our study cannot separate the benefits of moderate weight loss from the potential therapeutic effect of UGI tract bypass itself on the observed metabolic improvements.

Controversies in bariatric surgery

BACKGROUND

There are many controversies related to bariatric surgery. This review explores selected areas.

METHODS

A combination of randomized clinical trials (RCTs), systematic reviews and expert opinion have been brought together to highlight areas of importance or conflict.

RESULTS AND CONCLUSION

Metabolic surgery is an increasingly preferred term rather than bariatric or obesity surgery. Reporting should be standardized to include appropriate weight measures, valid disease measures and data on loss to follow-up. There are many putative mechanisms of effect of key bariatric procedures, but satiety and early satiation appear central. Weight loss must be durable. Long-term outcome studies (more than 10-year follow-up) show that biliopancreatic diversion is most effective, with 72 per cent excess weight loss (EWL). Roux-en-Y gastric bypass and laparoscopic adjustable gastric banding (LAGB) are equally effective, with 54 per cent EWL. There are no long-term data on vertical sleeve gastrectomy. Type II diabetes is a common and serious disease, usually associated with increased weight. Multiple RCTs have shown that bariatric surgery provides clear benefits over continuing with non-surgical therapies. The earlier the treatment, the more likely and durable will be the remission. Bariatric surgery should be available to all who are obese (body mass index over 30 kg/m(2) ). LAGB, a safe, effective, reversible outpatient procedure, is the author's preferred primary option.

The effect of duodenojejunostomy and sleeve gastrectomy on type 2 diabetes mellitus and gastrin secretion in Goto-Kakizaki rats

BACKGROUND

Bariatric surgery is a highly effective treatment of type 2 diabetes in patients with morbid obesity. The weight-loss independent improvement of glycemic control observed after these procedures has led to the discussion whether bariatric surgery can be introduced as treatment for type 2 diabetes in patients with a body mass index < 35 kg/m(2). We have studied the effects of two bariatric procedures on type 2 diabetes and on gastrointestinal hormone secretion in a lean diabetic animal model.

METHODS

Male Goto-Kakizaki rats, 17-18 weeks old, were randomized into three groups: duodenojejunostomy (DJ), sleeve gastrectomy (SG), or sham operation. During 36 postoperative weeks we evaluated body weight, fasting blood glucose, glucose tolerance, insulin, HbA1c, glucagon-like peptide 1, cholesterol parameters, triglycerides, total ghrelin, and gastrin.

RESULTS

Oral glucose tolerance was significantly improved for both DJ and SG at four weeks after surgery (p < 0.05). At the 34th postoperative week, SG had significantly lower area under the curve during oral glucose tolerance test compared to sham (p = 0.007). SG had significantly lower HbA1c compared to sham at 12 weeks; (mean ± SEM) 4.3 ± 0.1 % versus 5.2 ± 0.3 % (p < 0.05) and compared to both DJ and sham 34 weeks after surgery [median (75 %;25 %)] 5.2 (6.0; 4.3) % versus 7.0 (7.5; 6.7) % and 7.3 (7.6; 6.7) % (p = 0.009). Serum gastrin levels were markedly elevated for SG compared to DJ and sham; 188.0 (318.0; 121.0) versus 77.5 (114.0; 58.0) and 68.0 (90.0; 59.5) pmol/L (p = 0.004) at six weeks and 192.0 (587.8; 110.8) versus 65.5 (77.0; 59.0) and 69.5 (113.0; 55.5) (p = 0.001) 36 weeks after surgery.

CONCLUSION

Sleeve gastrectomy induces hypergastrinemia, lowers HbA1c, and improves glycemic control in Goto-Kakizaki rats. Sleeve gastrectomy is superior to duodenojejunostomy as treatment of type 2 diabetes mellitus in this animal model.

Biliopancreatic diversion with duodenal switch improves insulin sensitivity and secretion through caloric restriction

OBJECTIVE

To assess the rapid improvement of insulin sensitivity and β-cell function following biliopancreatic diversion with duodenal switch (BPD-DS) and determine the role played by caloric restriction in these changes.

METHODS

Standard meals were administrated before and on day 3, 4, and 5 after BPD-DS to measure total caloric intake, glucose excursion, insulin sensitivity, and secretion in matched type 2 diabetes and normoglycemic (NG) subjects. In a second set of study, other subjects with type 2 diabetes had the same meal tests prior to and after a 3-day caloric restriction identical to that observed after BPD-DS and then 3 days after actually undergoing BPD-DS.

RESULTS

Improvement of HOMA-IR occurred at day 3 after BPD-DS in diabetes and after 3 days of caloric restriction. The disposition index (DI) improved rapidly in diabetes after BPD-DS and to a similar extent after caloric restriction. DI was higher and did not change after BPD-DS in NG. Changes in glucagon-like peptide-1, gastric inhibitory peptide, peptide tyrosine tyrosine, ghrelin, and pancreatic polypeptide levels were not associated with modulation of DI in the participants.

CONCLUSIONS

Caloric restriction is the major mechanism underlying the early improvement of insulin sensitivity and β-cell function after BPD-DS in type 2 diabetes.

Efficacy of metabolic surgery on HbA1c decrease in type 2 diabetes mellitus patients with BMI <35 kg/m2--a review

High glycated hemoglobin A1c (HbA1c) is strongly correlated with developing type 2 diabetes mellitus (T2DM) complications; this study reviews the efficacy of various types of metabolic surgeries in reducing HbA1c levels in type 2 diabetics with BMI <35 kg/m(2). An electronic search of MEDLINE databases using terms 'metabolic surgery', type 2 diabetes mellitus, BMI <35 kg/m(2), and related keywords for studies published between 1987 and 2013. Data from 53 articles with 2,258 patients were selected for this review. The weighted mean change in HbA1c was -2.8 % (95 % CI -2.8 to -2.7, p < 0.01) and weighted mean BMI change was -5.5 kg/m(2) (95 % CI -5.6 to -5.4, p < 0.01). There was a strong correlation between weighted percentage mean change in HbA1c and BMI. Adjustable gastric banding and duodenal jejunal bypass were inferior to other surgeries in reducing BMI and HbA1c in BMI <35 kg/m(2). Metabolic surgery significantly decreases HbA1c in T2DM patients with BMI <35 kg/m(2) and that the magnitude of HbA1c change may be a useful surrogate of DM control.

Multidisciplinary diabetes care with and without bariatric surgery in overweight people: a randomised controlled trial

BACKGROUND

Bariatric surgery improves glycaemia in obese people with type 2 diabetes, but its effects are uncertain in overweight people with this disease. We aimed to identify whether laparoscopic adjustable gastric band surgery can improve glucose control in people with type 2 diabetes who were overweight but not obese.

METHODS

We did an open-label, parallel-group, randomised controlled trial between Nov 1, 2009, and June 30, 2013, at one centre in Melbourne, Australia. Patients aged 18-65 years with type 2 diabetes and a BMI between 25 and 30 kg/m2 were randomly assigned (1:1), by computer-generated random sequence, to receive either multidisciplinary diabetes care plus laparoscopic adjustable gastric band surgery or multidisciplinary diabetes care alone. The primary outcome was diabetes remission 2 years after randomisation, defined as glucose concentrations of less than 7.0 mmol/L when fasting and less than 11.1 mmol/L 2 h after 75 g oral glucose, at least two days after stopping glucose-lowering drugs. Analysis was by intention to treat. This trial is registered with the Australian New Zealand Clinical Trials Registry, number ACTRN12609000286246.

FINDINGS

51 patients were randomised to the multidisciplinary care plus gastric band group (n=25) or the multidisciplinary care only group (n=26), of whom 23 participants and 25 participants, respectively, completed follow-up to 2 years. 12 (52%) participants in the multidisciplinary care plus gastric band group and two (8%) participants in the multidisciplinary care only group achieved diabetes remission (difference in proportions 0.44, 95% CI 0.17-0.71; p=0.0012). One (4%) participant in the gastric band group needed revisional surgery and four others (17%) had a total of five episodes of food intolerance due to excessive adjustment of the band.

INTERPRETATION

When added to multidisciplinary care, laparoscopic adjustable gastric band surgery for overweight people with type 2 diabetes improves glycaemic control with an acceptable adverse event profile. Laparoscopic adjustable gastric band surgery is a reasonable treatment option for this population.

FUNDING

Monash University Centre for Obesity Research and Education and Allergan.

Recent advances in clinical practice challenges and opportunities in the management of obesity

Despite advances in understanding the roles of adiposity, food intake, GI and adipocyte-related hormones, inflammatory mediators, the gut-brain axis and the hypothalamic nervous system in the pathophysiology of obesity, the effects of different therapeutic interventions on those pathophysiological mechanisms are controversial. There are still no low-cost, safe, effective treatments for obesity and its complications. Currently, bariatric surgical approaches targeting the GI tract are more effective than non-surgical approaches in inducing weight reduction and resolving obesity-related comorbidities. However, current guidelines emphasise non-surgical approaches through lifestyle modification and medications to achieve slow weight loss, which is not usually sustained and may be associated with medication-related side effects. This review analyses current central, peripheral or hormonal targets to treat obesity and addresses challenges and opportunities to develop novel approaches for obesity.

Endoscopic duodenal-jejunal bypass liner rapidly improves type 2 diabetes

BACKGROUND

Bariatric procedures excluding the proximal small intestine improve glycemic control in type 2 diabetes within days. To gain insight into the mediators involved, we investigated factors regulating glucose homeostasis in patients with type 2 diabetes treated with the novel endoscopic duodenal-jejunal bypass liner (DJBL).

METHODS

Seventeen obese patients (BMI 30-50 kg/m(2)) with type 2 diabetes received the DJBL for 24 weeks. Body weight and type 2 diabetes parameters, including HbA1c and plasma levels of glucose, insulin, glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), and glucagon, were analyzed after a standard meal before, during, and 1 week after DJBL treatment.

RESULTS

At 24 weeks after implantation, patients had lost 12.7 ± 1.3 kg (p < 0.01), while HbA1c had improved from 8.4 ± 0.2 to 7.0 ± 0.2 % (p < 0.01). Both fasting glucose levels and the postprandial glucose response were decreased at 1 week after implantation and remained decreased at 24 weeks (baseline vs. week 1 vs. week 24: 11.6 ± 0.5 vs. 9.0 ± 0.5 vs. 8.6 ± 0.5 mmol/L and 1,999 ± 85 vs. 1,536 ± 51 vs. 1,538 ± 72 mmol/L/min, both p < 0.01). In parallel, the glucagon response decreased (23,762 ± 4,732 vs. 15,989 ± 3,193 vs. 13,1207 ± 1,946 pg/mL/min, p < 0.05) and the GLP-1 response increased (4,440 ± 249 vs. 6,407 ± 480 vs. 6,008 ± 429 pmol/L/min, p < 0.01). The GIP response was decreased at week 24 (baseline-115,272 ± 10,971 vs. week 24-88,499 ± 10,971 pg/mL/min, p < 0.05). Insulin levels did not change significantly. Glycemic control was still improved 1 week after explantation.

CONCLUSIONS

The data indicate DJBL to be a promising treatment for obesity and type 2 diabetes, causing rapid improvement of glycemic control paralleled by changes in gut hormones.

Effects on GLP-1, PYY, and leptin by direct stimulation of terminal ileum and cecum in humans: implications for ileal transposition

BACKGROUND

We do not have a unified, scientifically tested theory of causation for obesity and its co-morbidities, nor do we have explanations for the mechanics of the metabolic/bariatric surgery procedures. Integral to proffered hypotheses are the actions of the hormones glucagon-like peptide-1 (GLP-1), peptide YY (PYY), and leptin. The objective of this study was to obtain blood levels of GLP-1, PYY, and leptin after stimulation of the terminal ileum and cecum by a static infusion of a food hydrolysate in morbidly obese patients undergoing a duodenal switch procedure.

SETTING

University Hospital.

METHODS

Plasma levels of GLP-1, PYY, and leptin were obtained at 0, 30, 60, 90, and 120 minutes after instillation of 240 mL of a food hydrolysate into the ileum or cecum.

RESULTS

The mean±SD GLP-1 values by cecal stimulation for 0, 30, 60, 90, and 120 minutes were: 41.3±23.2; 39.6±21.8; 38.9±19.1; 47.4±22.3; 51.7±27.3 pM, and by ileal stimulation: 55.0±32.8; 83.4±16.1; 78.7±23.8; 84.7±23.5; 76.4±25.6. The mean±SD PYY values by cecal stimulation were: 62.1±24.8; 91.1±32.8; 102.1±39.6; 119.6±37.5; 130.3±36.7, and by ileal stimulation: 73.8±41.6; 138.1±17.7; 149.5±23.3; 165.7±24.3; 155.5±29.1. Percent change in PYY levels increased ~150%, GLP-1 increased ~50%, and leptin decreased ~20%.

CONCLUSION

Direct stimulation of the human terminal ileum and cecum by a food hydrolysate elicits significant plasma GLP-1 and PYY elevations and leptin decreases, peaking at 90-120 minutes. The ileal GLP-1 and PYY responses exceed those of the cecum, and the PYY effect is about 3-fold that of GLP-1. The results of this study question the satiety premise for ileal transposition.

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).

The sum of many parts: potential mechanisms for improvement in glucose homeostasis after bariatric surgery

Bariatric surgery has emerged as the most durably effective treatment of type 2 diabetes (DM). However, the mechanisms governing improvement in glucose homeostasis have yet to be fully elucidated. In this review we discuss the various types of surgical interventions and the multitude of factors that potentially mediate the effects on glycemia, such as altered delivery of nutrients to the distal ileum, duodenal exclusion, gut hormone changes, bile acid reabsorption, and amino acid metabolism. Accumulating evidence that some of these changes seem to be independent of weight loss questions the rationale of using body mass index as the major indication for surgery in diabetic patients. Understanding the complex mechanisms and interactions underlying improved glycemic control could lead to novel therapeutic targets and would also allow for greater individualization of therapy and optimization of surgical outcomes.

Surgical control of obesity and diabetes: the role of intestinal vs. gastric mechanisms in the regulation of body weight and glucose homeostasis

OBJECTIVE

To elucidate the specific role of gastric vs. intestinal manipulations in the regulation of body weight and glucose homeostasis.

DESIGN AND METHODS

The effects of intestinal bypass alone (duodenal-jejunal bypass -DJB) and gastric resection alone (SG) in Zucker Diabetic Fatty (ZDF) rats were compared. Additional animals underwent a combination procedure (SG + DJB). Outcome measures included changes in weight, food intake (FI), oral glucose tolerance (GT) and gut hormones.

RESULTS

DJB did not substantially affect weight and FI, whereas SG significantly reduced weight gain and food consumption. DJB rats showed weight-independent improvement in GT, which improved less after SG. Furthermore, SG significantly suppressed plasma ghrelin and increased insulin, glucagon like peptide-1 (GLP-1), glucose-dependent insulinotropic peptide and peptide YY response to oral glucose whereas DJB had no effects on postprandial levels of these hormones. DJB restored postprandial glucagon suppression in diabetic rats whereas SG did not affect glucagon response. The combination procedure (SG + DJB) induced greater weight loss and better GT than SG alone without reducing food intake further.

CONCLUSIONS

These findings reveal a dominant role of the stomach in the regulation of body weight and incretin response to oral glucose whereas intestinal bypass primarily affects glucose homeostasis by a weight-, insulin- and incretin-independent mechanism.

Role of proximal gut exclusion from food on glucose homeostasis in patients with Type 2 diabetes

AIMS

To report Type 2 diabetes-related outcomes after the implantation of a duodenal-jejunal bypass liner device and to investigate the role of proximal gut exclusion from food in glucose homeostasis using the model of this device.

METHODS

Sixteen patients with Type 2 diabetes and BMI <36 kg/m(2) were evaluated before and 1, 12 and 52 weeks after duodenal-jejunal bypass liner implantation and 26 weeks after explantation. Mixed-meal tolerance tests were conducted over a period of 120 min and glucose, insulin and C-peptide levels were measured. The Matsuda index and the homeostatic model of assessment of insulin resistance were used for the estimation of insulin sensitivity and insulin resistance. The insulin secretion rate was calculated using deconvolution of C-peptide levels.

RESULTS

Body weight decreased by 1.3 kg after 1 week and by 2.4 kg after 52 weeks (P < 0.001). One year after duodenal-jejunal bypass liner implantation, the mean (sem) HbA(1c) level decreased from 71.3 (2.4) mmol/mol (8.6[0.2]%) to 58.1 (4.4) mmol/mol (7.5 [0.4]%) and mean (sem) fasting glucose levels decreased from 203.3 (13.5) mg/dl to 155.1 (13.1) mg/dl (both P < 0.001). Insulin sensitivity improved by >50% as early as 1 week after implantation as measured by the Matsuda index and the homeostatic model of assessment of insulin resistance (P < 0.001), but there was a trend towards deterioration in all the above-mentioned variables 26 weeks after explantation. Fasting insulin levels, insulin area under the curve, fasting C-peptide, C-peptide area under the curve, fasting insulin and total insulin secretion rates did not change during the duodenal-jejunal bypass liner implantation period or after explantation.

CONCLUSIONS

The duodenal-jejunal bypass liner improves glycaemia in overweight and obese patients with Type 2 diabetes by rapidly improving insulin sensitivity. A reduction in hepatic glucose output is the most likely explanation for this improvement.

Duodenal-jejunal bypass liners: outcomes in glycaemic control and weight loss

PURPOSE OF REVIEW

Duodenal-jejunal bypass liners (DJBLs) are a novel therapy with potential treating a range of metabolic diseases. This review discusses the weight loss and glycaemic improvements observed following the use of the DJBL.

RECENT FINDINGS

We summarize the evidence for the clinical application of DJBL to date. Within this, we outline the evidence available on the mechanisms of the observed effects.

SUMMARY

Based on the most recent trials, we cannot fully mimic the clinical or physiological effects of bariatric surgery with this device, but we are getting closer.

Gastrointestinal hormones and bariatric surgery-induced weight loss

Obesity continues to be a major public health problem in the United States and worldwide. While recent statistics have demonstrated that obesity rates have begun to plateau, more severe classes of obesity are accelerating at a faster pace with important implications in regards to treatment. Bariatric surgery has a profound and durable effect on weight loss, being to date one of the most successful interventions for obesity.

OBJECTIVE

To provide updates to the possible role of gut hormones in post bariatric surgery weight loss and weight loss maintenance.

DESIGN AND METHODS

The current review examines the changes in gastro-intestinal hormones with bariatric surgery and the potential mechanisms by which these changes could result in decreased weight and adiposity.

RESULTS

The mechanism by which bariatric surgery results in body weight changes is incompletely elucidated, but it clearly goes beyond caloric restriction and malabsorption.

CONCLUSION

Changes in gastro-intestinal hormones, including increases in GLP-1, PYY, and oxyntomodulin, decreases in GIP and ghrelin, or the combined action of all these hormones might play a role in induction and long-term maintenance of weight loss.

Gastric bypass in Type 2 diabetes with BMI < 30: weight and weight loss have a major influence on outcomes

AIM

To assess factors influencing glycaemic control following gastric bypass surgery in patients with Type 2 diabetes and BMI< 30 kg/m(2) .

METHODS

Prospective longitudinal study of 103 patients with inadequate glycaemic control who underwent gastric bypass surgery at Soonchunhyang University, Seoul, Korea (n = 66) and Min-Sheng General Hospital, Taipei, Taiwan (n = 37). Procedures were performed August 2009 to January 2011. Key outcome measures were excellent glycaemic control of Type 2 diabetes defined as HbA1c < 42 mmol/mol (≤6%); inadequate response defined as HbA1c > 53 mmol/mol (> 7%). Analysis was conducted using binary logistic regression, and cut-points obtained from receiver operator characteristics.

RESULTS

Excellent glycaemic control was achieved in 31 (30%) at 1 year. Diabetes duration of < 7 years and BMI > 27 kg/m(2) provided independent predictors and useful cut-points. Likelihood of excellent glycaemic control for an individual could be estimated using loge (Odds) = -6.7 + (0.26 × BMI) + (-1.2 × diabetes duration). Baseline BMI of < 27 kg/m(2) and baseline C-peptide of < 2.0ng/ml, best predicted a poor glycaemic response. In those with favourable baseline characteristics percentage weight loss (%WL) had a dominant influence on glycaemic outcomes. Baseline C-peptide (> 2.4 ng/ml) and subsequent percentage weight loss (> 16%) were associated with excellent glycaemic control. Higher BMI was associated with greater percentage weight loss.

CONCLUSION

In patients with Type 2 diabetes and BMI < 30 kg/m(2) , glycaemic response to gastric bypass is predicted by higher baseline BMI, shorter disease duration and higher fasting C-peptide. Post-surgery weight loss has a dominant effect. Baseline BMI and weight loss have a major influence on outcomes.

Endoscopic duodenal-jejunal bypass liner rapidly improves type 2 diabetes

BACKGROUND

Bariatric procedures excluding the proximal small intestine improve glycemic control in type 2 diabetes within days. To gain insight into the mediators involved, we investigated factors regulating glucose homeostasis in patients with type 2 diabetes treated with the novel endoscopic duodenal-jejunal bypass liner (DJBL).

METHODS

Seventeen obese patients (BMI 30-50 kg/m(2)) with type 2 diabetes received the DJBL for 24 weeks. Body weight and type 2 diabetes parameters, including HbA1c and plasma levels of glucose, insulin, glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), and glucagon, were analyzed after a standard meal before, during, and 1 week after DJBL treatment.

RESULTS

At 24 weeks after implantation, patients had lost 12.7 ± 1.3 kg (p < 0.01), while HbA1c had improved from 8.4 ± 0.2 to 7.0 ± 0.2 % (p < 0.01). Both fasting glucose levels and the postprandial glucose response were decreased at 1 week after implantation and remained decreased at 24 weeks (baseline vs. week 1 vs. week 24: 11.6 ± 0.5 vs. 9.0 ± 0.5 vs. 8.6 ± 0.5 mmol/L and 1,999 ± 85 vs. 1,536 ± 51 vs. 1,538 ± 72 mmol/L/min, both p < 0.01). In parallel, the glucagon response decreased (23,762 ± 4,732 vs. 15,989 ± 3,193 vs. 13,1207 ± 1,946 pg/mL/min, p < 0.05) and the GLP-1 response increased (4,440 ± 249 vs. 6,407 ± 480 vs. 6,008 ± 429 pmol/L/min, p < 0.01). The GIP response was decreased at week 24 (baseline-115,272 ± 10,971 vs. week 24-88,499 ± 10,971 pg/mL/min, p < 0.05). Insulin levels did not change significantly. Glycemic control was still improved 1 week after explantation.

CONCLUSIONS

The data indicate DJBL to be a promising treatment for obesity and type 2 diabetes, causing rapid improvement of glycemic control paralleled by changes in gut hormones.

Effects of bariatric surgery on glucose homeostasis and type 2 diabetes

Obesity is an important risk factor for type 2 diabetes mellitus (T2DM). Weight loss improves the major factors involved in the pathogenesis of T2DM, namely insulin action and beta cell function, and is considered a primary therapy for obese patients who have T2DM. Unfortunately, most patients with T2DM fail to achieve successful weight loss and adequate glycemic control from medical therapy. In contrast, bariatric surgery causes marked weight loss and complete remission of T2DM in most patients. Moreover, bariatric surgical procedures that divert nutrients away from the upper gastrointestinal tract are more successful in producing weight loss and remission of T2DM than those that simply restrict stomach capacity. Although upper gastrointestinal tract bypass procedures alter the metabolic response to meal ingestion, by increasing early postprandial plasma concentrations of glucagon-like peptide 1 and insulin, it is not clear whether these effects make an important contribution to long-term control of glycemia and T2DM once substantial surgery-induced weight loss has occurred. Nonetheless, the effects of surgery on body weight and metabolic function indicate that bariatric surgery should be part of the standard therapy for T2DM. More research is needed to advance our understanding of the physiological effects of different bariatric surgical procedures and possible weight loss-independent factors that improve metabolic function and contribute to the resolution of T2DM.