Hormone Changes Affecting Energy Homeostasis after Metabolic Surgery

Gut motility and hormone changes after bariatric procedures

PURPOSE OF REVIEW

Metabolic and bariatric surgery (MBS) and endoscopic bariatric therapies (EBT) are being increasingly utilized for the management of obesity. They work through multiple mechanisms, including restriction, malabsorption, and changes in the gastrointestinal hormonal and motility.

RECENT FINDINGS

Roux-en-Y gastric bypass (RYGB) and laparoscopic sleeve gastrectomy (LSG) cause decrease in leptin, increase in GLP-1 and PYY, and variable changes in ghrelin (generally thought to decrease). RYGB and LSG lead to rapid gastric emptying, increase in small bowel motility, and possible decrease in colonic motility. Endoscopic sleeve gastroplasty (ESG) causes decrease in leptin and increase in GLP-1, ghrelin, and PYY; and delayed gastric motility.

SUMMARY

Understanding mechanisms of action for MBS and EBT is critical for optimal care of patients and will help in further refinement of these interventions.

The Effect of Bariatric Surgery on Irisin Level: a Systematic Review and Meta-analysis

This systematic analysis and meta-analysis aimed to assess changes in the plasma levels of irisin after bariatric surgery. Search strategy, study screening, and data gathering were all conducted using a checklist and the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). Two researchers independently extracted the data, and a third person was included to resolve disagreements. The results illustrated no statistical difference between before and after surgery irisin plasma levels (P = 0.216, 95% CI = -1.812-0.410, SMD = -0.701, I-squared = 94.9%). BMI exhibited a meaningful decline after surgery compared to preoperative values (SMD = -3.09, 95% CI = -4.59--1.59, I-squared = 95.5%, P<0.05). According to our analysis, it can be concluded that irisin plasma levels are not significantly influenced by bariatric surgery.

Mucosal and hormonal adaptations after Roux-en-Y gastric bypass

The aim of this study was to perform a comprehensive literature review regarding the relevant hormonal and histologic changes observed after Roux-en-Y gastric bypass (RYGB). We aimed to describe the relevant hormonal (glucagon-like peptides 1 and 2 [GLP-1 and GLP-2], peptide YY [PYY], oxyntomodulin [OXM], bile acids [BA], cholecystokinin [CCK], ghrelin, glucagon, gastric inhibitory polypeptide [GIP], and amylin) profiles, as well as the histologic (mucosal cellular) adaptations happening after patients undergo RYGB. Our review compiles the current evidence and furthers the understanding of the rationale behind the food intake regulatory adaptations occurring after RYGB surgery. We identify gaps in the literature where the potential for future investigations and therapeutics may lie. We performed a comprehensive database search without language restrictions looking for RYGB bariatric surgery outcomes in patients with pre- and postoperative blood work hormonal profiling and/or gut mucosal biopsies. We gathered the relevant study results and describe them in this review. Where human findings were lacking, we included animal model studies. The amalgamation of physiologic, metabolic, and cellular adaptations following RYGB is yet to be fully characterized. This constitutes a fundamental aspiration for enhancing and individualizing obesity therapy.

Differential effects of RYGB surgery and best medical treatment for obesity-diabetes on intestinal and islet adaptations in obese-diabetic ZDSD rats

Modification of gut-islet secretions after Roux-En-Y gastric bypass (RYBG) surgery contributes to its metabolic and anti-diabetic benefits. However, there is limited knowledge on tissue-specific hormone distribution post-RYGB surgery and how this compares with best medical treatment (BMT). In the present study, pancreatic and ileal tissues were excised from male Zucker-Diabetic Sprague Dawley (ZDSD) rats 8-weeks after RYGB, BMT (daily oral dosing with metformin 300mg/kg, fenofibrate 100mg/kg, ramipril 1mg/kg, rosuvastatin 10mg/kg and subcutaneous liraglutide 0.2mg/kg) or sham operation (laparotomy). Insulin, glucagon, somatostatin, PYY, GLP-1 and GIP expression patterns were assessed using immunocytochemistry and analyzed using ImageJ. After RYGB and BMT, body weight and plasma glucose were decreased. Intestinal morphometry was unaltered by RYGB, but crypt depth was decreased by BMT. Intestinal PYY cells were increased by both interventions. GLP-1- and GIP-cell counts were unchanged by RYGB but BMT increased ileal GLP-1-cells and decreased those expressing GIP. The intestinal contents of PYY and GLP-1 were significantly enhanced by RYGB, whereas BMT decreased ileal GLP-1. No changes of islet and beta-cell area or proliferation were observed, but the extent of beta-cell apoptosis and islet integrity calculated using circularity index were improved by both treatments. Significantly decreased islet alpha-cell areas were observed in both groups, while beta- and PYY-cell areas were unchanged. RYGB also induced a decrease in islet delta-cell area. PYY and GLP-1 colocalization with glucagon in islets was significantly decreased in both groups, while co-staining of PYY with glucagon was decreased and that with somatostatin increased. These data characterize significant cellular islet and intestinal adaptations following RYGB and BMT associated with amelioration of obesity-diabetes in ZDSD rats. The differential responses observed and particularly those within islets, may provide important clues to the unique ability of RYGB to cause diabetes remission.

Intestinal alteration of α-gustducin and sweet taste signaling pathway in metabolic diseases is partly rescued after weight loss and diabetes remission

Carbohydrates and sweeteners are detected by the sweet taste receptor in enteroendocrine cells (EECs). This receptor is coupled to the gustducin G-protein, which α-subunit is encoded by GNAT3 gene. In intestine, the activation of sweet taste receptor triggers a signaling pathway leading to GLP-1 secretion, an incretin hormone. In metabolic diseases, GLP-1 concentration and incretin effect are reduced while partly restored after Roux-en-Y gastric bypass (RYGB). We wondered if the decreased GLP-1 secretion in metabolic diseases is caused by an intestinal defect in sweet taste transduction pathway. In our RNA-sequencing of EECs, GNAT3 expression is decreased in patients with obesity and type 2 diabetes compared with normoglycemic obese patients. This prompted us to explore sweet taste signaling pathway in mice with metabolic deteriorations. During obesity onset in mice, Gnat3 expression was downregulated in EECs. After metabolic improvement with enterogastro anastomosis surgery in mice (a surrogate of the RYGB in humans), the expression of Gnat3 increased in the new alimentary tract and glucose-induced GLP-1 secretion was improved. To evaluate if high-fat diet-induced dysbiotic intestinal microbiota could explain the changes in the expression of sweet taste α-subunit G-protein, we performed a fecal microbiota transfer in mice. However, we could not conclude if dysbiotic microbiota impacted or not intestinal Gnat3 expression. Our data highlight that metabolic disorders were associated with altered gene expression of sweet taste signaling in intestine. This could contribute to impaired GLP-1 secretion that is partly rescued after metabolic improvement.NEW & NOTEWORTHY Our data highlighted 1) the sweet taste transduction pathway in EECs plays pivotal role for glucose homeostasis at least at gene expression level; 2) metabolic disorders lead to altered gene expression of sweet taste signaling pathway in intestine contributing to impaired GLP-1 secretion; and 3) after surgical intestinal modifications, increased expression of GNAT3, encoding α-gustducin contributed to metabolic improvement.

Are the Changes in Gastrointestinal Hormone Secretion Necessary for the Success of Bariatric Surgery? A Critical Review of the Literature

Ghrelin, glucagon-like peptide-1 (GLP-1), and peptide YY (PYY) are involved in energy balance regulation and glucose homeostasis. Obesity is characterized by lower fasting levels and blunted postprandial responses of ghrelin, GLP-1, and possibly PYY. Both Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) have been shown to increase postprandial GLP-1 and PYY levels. Human studies have shown that enhanced postprandial GLP-1 and PYY release are associated with favorable weight loss outcomes after RYGB. However, studies in knockout mice have shown that GI hormones are not required for the primary metabolic effects of bariatric surgery. Here, we summarize the complex interaction between obesity, bariatric surgery, and GI hormones in order to determine the exact role of GI hormones in the success of bariatric surgery.

Comparison Between Laparoscopic Sleeve Gastrectomy and Laparoscopic Greater Curvature Plication Treatments for Obesity: an Updated Systematic Review and Meta-Analysis

Bariatric surgery has been widely performed to treat morbid obesity. Our meta-analysis aims to provide an updated comparison between laparoscopic sleeve gastrectomy (LSG) and laparoscopic greater curvature plication (LGCP). Medline, EMBASE, Scopus, and Cochrane Central were searched. Ongoing clinical trials were identified from the clinicaltrials.gov website. References of the chosen literatures were manually reviewed for additional relevant studies. As a result, a total of 18 studies involving 1329 patients were selected. We demonstrated a significant higher excess weight loss (%EWL) after LSG at the 1-, 3-, 6-, 12-, and 18-month follow-up time points. However, no significant difference was found at 36 months. Body Mass Index Loss (BMIL) was better after LSG than LGCP at 12 and 24 months. The difference in the improvement of comorbidities (i.e., T2-DM, hypertension, and sleep apnea) did not reach statistical significance. The complications (i.e., bleeding, stenosis, leak, and abdominal pain), operative time, and length of hospital stay were comparable. More patients undergoing LGCP experienced nausea and vomiting. We obtained some different and new results compared to the previously published meta-analysis. Our meta-analysis showed significantly higher %EWL at 24 months (Z=2.08, p=0.04), significantly higher BMIL at 36 months (Z=9.11, p <0.00001), and significantly higher costs (Z=2.87, p=0.004) in the LSG group. In addition, for the first time, complications (i.e., GERD, wound infection, port-site hernia, and mortality) and improvement of dyslipidemia were compared between the two techniques. According to our pooled data, no significant differences were found in any of the above aspects. In conclusion, LSG is superior to LGCP with regard to providing effective weight loss in the short- and mid-term. LSG has a lower rate of minor complications, but was less effective when considering cost. The two procedures are similar in terms of improvement of comorbidities, major complications, operative time, and length of stay.

The Leading Role of Peptide Tyrosine Tyrosine in Glycemic Control After Roux-en-Y Gastric Bypass in Rats

AIMS

Roux-en-Y gastric bypass (RYGB) is one of the most effective surgical therapies for the rapid resolution of type 2 diabetes. However, the mechanisms underlying the entero-hormonal response after surgery and the role of peptide tyrosine tyrosine (PYY) in the restoration of normoglycemia are still not clear.

METHODS

We reproduced the RYGB technique in Wistar and Goto-Kakizaki rats and performed serum hormonal, histological, and hormonal-infusion test.

RESULTS

Using the diabetic Goto-Kakizaki (GK) rat model, we demonstrated that PYY plasma levels showed a remarkable peak approximately 30 min earlier than GLP-1 or GIP after mixed-meal administration in RYGB-operated rats with PYY. The GLP-1 and GIP areas under the curve (AUCs) increased after RYGB in GK rats. Additionally, the findings suggested that PYY (3-36) infusion led to increased GLP-1 and GIP plasma levels close to those obtained after a meal. Finally, the number of GLP-1-positive cells appeared to increase in the three segments of the small intestine in GK-RYGB-operated rats beyond the early presence of nutrient stimulation in the ileum. Nevertheless, PYY-positive cell numbers appeared to increase only in the ileum.

CONCLUSION

At least in rats, these data demonstrate an earlier essential role for PYY in gut hormone regulation after RYGB. We understand that PYY contributes to GLP-1 and GIP release and there must be the existence of enteroendocrine communication routes between the distal and proximal small intestine.

Order of discontinuation of glucose-lowering medications following bariatric surgery

AIMS

To assess the order of glucose-lowering medication (GLM) discontinuation following bariatric surgery among patients taking ≥2 GLMs.

METHODS

Patients with diabetes mellitus taking ≥2 GLM classes who underwent bariatric surgery were identified using health claims data from the United States. The order of discontinuation was assessed in patients taking ≥2 GLM classes by comparing each GLM class to the other classes in aggregate. Descriptive statistics and Poisson regression were used to assess the order of discontinuation and changes in trends in the order of discontinuation.

RESULTS

Overall, 12,244 of 26,651 patients with type 2 diabetes who underwent bariatric surgery were taking ≥2 GLM classes. When each GLM class was assessed separately, fewer than 50% of patients had metformin, sulfonylurea, thiazolidinedione, DPP-4 inhibitor, SGLT2 inhibitor, glucosidase inhibitor, or insulin discontinued first when compared to the other classes in aggregate. Between 2008 and 2014, thiazolidinediones were increasingly more likely to be the first GLM discontinued (p = 0.0432). Slightly more than 50% of patients whose GLM regimen included a sulfonylurea discontinued the sulfonylurea first despite clinical recommendations.

CONCLUSIONS

From a population level, there was no consistent approach in the order of discontinuation of GLM classes in patients following bariatric surgery.

Type 2 diabetes is associated with impaired jejunal enteroendocrine GLP-1 cell lineage in human obesity

Objectives

Altered enteroendocrine cell (EEC) function in obesity and type 2 diabetes is not fully understood. Understanding the transcriptional program that controls EEC differentiation is important because some EEC types harbor significant therapeutic potential for type 2 diabetes.

Methods

EEC isolation from jejunum of obese individuals with (ObD) or without (Ob) type 2 diabetes was obtained with a new method of cell sorting. EEC transcriptional profiles were established by RNA-sequencing in a first group of 14 Ob and 13 ObD individuals. EEC lineage and densities were studied in the jejunum of a second independent group of 37 Ob, 21 ObD and 22 non obese (NOb) individuals.

Results

The RNA seq analysis revealed a distinctive transcriptomic signature and a decreased differentiation program in isolated EEC from ObD compared to Ob individuals. In the second independent group of ObD, Ob and NOb individuals a decreased GLP-1 cell lineage and GLP-1 maturation from proglucagon, were observed in ObD compared to Ob individuals. Furthermore, jejunal density of GLP-1-positive cells was significantly reduced in ObD compared to Ob individuals.

Conclusions

These results highlight that the transcriptomic signature of EEC discriminate obese subjects according to their diabetic status. Furthermore, type 2 diabetes is associated with reduced GLP-1 cell differentiation and proglucagon maturation leading to low GLP-1-cell density in human obesity. These mechanisms could account for the decrease plasma GLP-1 observed in metabolic diseases.

Bariatric Surgery and Type 1 Diabetes: Unanswered Questions

In recent decades there has been an alarming increase in the prevalence of obesity in patients with type 1 diabetes leading to the development of insulin resistance and cardiometabolic complications, with mechanisms poorly clarified. While bariatric surgery has long been considered an effective treatment option for patients with type 2 diabetes, the evidence regarding its benefits on weight loss and the prevention of complications in T1DM patients is scarce, with controversial outcomes. Bariatric surgery has been associated with a significant reduction in daily insulin requirement, along with a considerable reduction in body mass index, results which were sustained in the long term. Furthermore, studies suggest that bariatric surgery in type 1 diabetes results in the improvement of comorbidities related to obesity including hypertension and dyslipidemia. However, regarding glycemic control, the reduction of mean glycosylated hemoglobin was modest or statistically insignificant in most studies. The reasons for these results are yet to be elucidated; possible explanations include preservation of beta cell mass and increased residual function post-surgery, improvement in insulin action, altered GLP-1 function, timing of surgery, and association with residual islet cell mass. A number of concerns regarding safety issues have arisen due to the reporting of peri-operative and post-operative adverse events. The most significant complications are metabolic and include diabetic ketoacidosis, severe hypoglycemia and glucose fluctuations. Further prospective clinical studies are required to provide evidence for the effect of bariatric surgery on T1DM patients. The results may offer a better knowledge for the selection of people living with diabetes who will benefit more from a metabolic surgery.

The influence of bariatric surgery on serum levels of irisin and nesfatin-1

Introduction: Bariatric surgery is associated with multiple endocrine and metabolic changes. Irisin and nesfatin-1 have recently been described as regulatory peptides involved in obesity-related insulin resistance. Our aim was to analyze the changes of those two molecules observed in patients after bariatric procedures. Materials and methods: This prospective study involved 40 patients treated for morbid obesity. Irisin and nesfatin-1 were measured before, 6 months and 1 year after surgical intervention. We also gathered demographic data, information concerning comorbidities, factors related to the surgery and outcomes of bariatric treatment. Results: Twenty-seven patients completed the study (15 females). The mean age of the group was 43.5 ± 10.4 years. Six (22.2%) patients were submitted to Laparoscopic Sleeve Gastrectomy and 21 (77.8%) patients were submitted to Laparoscopic Roux-en-Y Gastric Bypass. The participants in our study achieved significant weight loss. The irisin level remained stable in the whole study group during all three measurements included in our study protocol (p = .71). Our study group presented a reduction of the nesfatin-1 level 6 months after bariatric surgery and a slight further decrease after one-year observation, although these changes were also not significant (p = .17). Conclusions: We did not find any significant correlation between changes of irisin or nesfatin-1 level and bariatric surgery, as an aid in the regulation of glucose metabolism.

Is reduction in appetite beneficial for body weight management in the context of overweight and obesity? Yes, according to the SATIN (Satiety Innovation) study

New dietary-based concepts are needed for treatment and effective prevention of overweight and obesity. The primary objective was to investigate if reduction in appetite is associated with improved weight loss maintenance. This cohort study was nested within the European Commission project Satiety Innovation (SATIN). Participants achieving ≥8% weight loss during an initial 8-week low-energy formula diet were included in a 12-week randomised double-blind parallel weight loss maintenance intervention. The intervention included food products designed to reduce appetite or matching controls along with instructions to follow national dietary guidelines. Appetite was assessed by ad libitum energy intake and self-reported appetite evaluations using visual analogue scales during standardised appetite probe days. These were evaluated at the first day of the maintenance period compared with baseline (acute effects after a single exposure of intervention products) and post-maintenance compared with baseline (sustained effects after repeated exposures of intervention products) regardless of randomisation. A total of 181 participants (forty-seven men and 134 women) completed the study. Sustained reduction in 24-h energy intake was associated with improved weight loss maintenance (R 0·37; P = 0·001), whereas the association was not found acutely (P = 0·91). Suppression in self-reported appetite was associated with improved weight loss maintenance both acutely (R −0·32; P = 0·033) and sustained (R −0·33; P = 0·042). Reduction in appetite seems to be associated with improved body weight management, making appetite-reducing food products an interesting strategy for dietary-based concepts.

The Role of Bariatric Surgery on Diabetes and Diabetic Care Compliance

PURPOSE OF REVIEW

Bariatric surgery is a durable and long-term solution to treat both obesity and its associated comorbidities, specifically type 2 diabetes mellitus (T2DM). Many studies have demonstrated the benefits of bariatric surgery on T2DM, but weight recidivism along with recurrence of comorbidities can be seen following these procedures. Patient compliance post-bariatric surgery is linked to weight loss outcomes and comorbidity improvement/resolution. The role of compliance with respect to T2DM medication in bariatric patients specifically has not recently been examined. This article seeks to review the role of bariatric surgery on short- and long-term resolution of T2DM, recurrence, and compliance with T2DM medication following bariatric surgery.

RECENT FINDINGS

Seven randomized control trials have examined metabolic surgery versus medical therapy in glycemic control in patients meeting criteria for severe obesity. Six out of seven studies demonstrate a significant advantage in the surgical arms with regards to glycemic control, as well as secondary endpoints such as weight loss, serum lipid levels, blood pressure, renal function, and other parameters. While patient compliance with lifestyle modifications post-bariatric surgery is linked to weight loss outcomes, there are no studies to date that directly evaluate the role of lifestyle modifications and T2DM medication adherence in the management of T2DM post-bariatric surgery. Bariatric surgery is an effective treatment option to achieve long-term weight loss and resolution of obesity-related medical comorbidities, specifically T2DM. Patient compliance to lifestyle modifications post-bariatric surgery is linked to weight loss outcomes and comorbidity resolution. The role of diabetic care compliance in bariatric patient outcomes, however, is poorly understood. Further studies are needed to elucidate the predictors and associated risk factors for non-compliance in this patient population.

The preprohormone expression profile of enteroendocrine cells following Roux-en-Y gastric bypass in rats

OBJECTIVE

Roux-en-Y gastric bypass (RYGB) leads to rapid remission of type 2 diabetes (T2D) and sustained body weight loss, but the underlying molecular mechanisms are still not fully understood. To further elucidate these mechanisms and identify potentially novel preprohormone encoding genes with anti-diabetic and/or anti-obesity properties, we performed a comprehensive analysis of gene expression changes in enteroendocrine cells after RYGB in diet-induced obese (DIO) rats.

METHODS

The mRNA expression profiles of enteroendocrine cell enriched samples were characterized at 9, 22 and 60 days after RYGB surgery in a DIO rat model. Enteroendocrine cells were identified by chromogranin A immunohistochemistry and isolated by laser capture microdissection (LCM) from five regions covering the full rostro-caudal extension of the gastrointestinal (GI) tract. RNA sequencing and bioinformatic analyses were subsequently applied to identify differentially expressed preprohormone encoding genes.

RESULTS

From the analysis of enteroendocrine cell mRNA expression profiles, a total of 54 preprohormones encoding genes were found to be differentially regulated at one or more time-points following RYGB. These included well-known RYGB associated preprohormone genes (e.g. Gcg, Cck, Gip, Pyy and Sct) and less characterized genes with putative metabolic effects (e.g. Nmu, Guca2a, Guca2b, Npw and Adm), but also 16 predicted novel preprohormone genes. Among the list of gene transcripts, Npw, Apln and Fam3d were further validated using in situ mRNA hybridization and corresponding peptides were characterized for acute effects on food intake and glucose tolerance in mice.

CONCLUSION

We present a comprehensive mRNA expression profile of chromogranin A positive enteroendocrine cells following RYGB in rats. The data provides a region-specific characterization of all regulated preprohormone encoding genes in the rat GI tract including 16 not hitherto known. The comprehensive catalogue of preprohormone expression changes may support our understanding of hormone mediated effects of RYGB on diabetes remission and body weight reduction.

Is reducing appetite beneficial for body weight management in the context of overweight and obesity? A systematic review and meta-analysis from clinical trials assessing body weight management after exposure to satiety enhancing and/or hunger reducing products

This review aims to investigate whether interventions that enhance satiety and/or reduce hunger lead to beneficial effects on body weight management in the context of overweight and obesity. A comprehensive review protocol was prepared before conducting a systematic search in PubMed identifying 517 papers with 12 meeting the inclusion criteria. A thorough risk of bias assessment was performed based on the Cochrane collaboration's tool for assessing risk of bias. Based on a meta-analysis, the average of 75 subjects exposed to satiety enhancing and/or hunger reducing foods during more than 8 weeks coincidently reduced their body weight by 3.60 (1.05; 6.15) kg (mean (95% confidence interval)) more compared with controls. Two studies analysed whether individual reductions in appetite were associated with body weight. Decreased ad libitum energy intake after exposure to the satiety enhancing and/or hunger reducing interventions explained 58% (P < 0.001) and 23% (P < 0.001) of the variations in the subsequent weight losses over 12 and 8 weeks, respectively. Robust acute effects on appetite were found equally likely to be linked to improved body weight management as sustained effects. Satiety enhancing and/or hunger reducing interventions are supported to improve body weight management, but studies specifically designed to demonstrate a causal link remain needed.

Comparison of surgical versus diet-induced weight loss on appetite regulation and metabolic health outcomes

Bariatric surgery is associated with significant and sustained weight loss and improved metabolic outcomes. It is unclear if weight loss alone is the main mechanism of improved metabolic health. The purpose of this trial was to compare indices of appetite regulation, insulin sensitivity and energy intake (EI) between participants achieving 10 kg of weight loss via Roux-en-Y Gastric Bypass (RYGB) or dietary restriction (DIET); intake of a very low calorie liquid diet (800 kcal/d; 40% protein, 40% fat, 20% carbohydrate that matched the post-RYGB dietary protocol). Adults qualifying for bariatric surgery were studied before and after 10 kg of weight loss (RYGB [n = 6]) or DIET [n = 17]). Appetite (hunger, satiety, and prospective food consumption [PFC]), appetite-related hormones, and metabolites (ghrelin, PYY, GLP-1, insulin, glucose, free fatty acids [FFA], and triglycerides [TG]) were measured in the fasting state and every 30 min for 180 min following breakfast. Participants were provided lunch to evaluate acute ad libitum EI, which was similarly reduced in both groups from pre to post weight loss. Fasting ghrelin was reduced to a greater extent following RYGB compared to DIET (P = 0.04). Area under the curve (AUC) for ghrelin (P = 0.01), hunger (P < 0.01) and PFC (P < 0.01) increased after DIET compared to RYGB, following 10 kg weight loss. Satiety AUC increased after RYGB and decreased after DIET (P < 0.01). Glucose and insulin (fasting and AUC) decreased in both groups. FFA increased in both groups, with a greater increase in AUC seen after RYGB versus DIET (P = 0.02). In summary, appetite-related indices were altered in a manner that, if maintained, may promote a sustained reduction in energy intake with RYGB compared to DIET. Future work with a larger sample size and longer follow-up will be important to confirm and extend these findings.

Weight Loss Medications in Young Adults after Bariatric Surgery for Weight Regain or Inadequate Weight Loss: A Multi-Center Study

This paper presents a retrospective cohort study of weight loss medications in young adults aged 21 to 30 following Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) between November 2000 and June 2014. Data were collected from patients who used topiramate, phentermine, and/or metformin postoperatively. Percentage of patients achieving ≥5%, ≥10%, or ≥15% weight loss on medications was determined and percent weight change on each medication was compared to percent weight change of the rest of the cohort. Our results showed that 54.1% of study patients lost ≥5% of their postsurgical weight; 34.3% and 22.9% lost ≥10% and ≥15%, respectively. RYGB had higher median percent weight loss (−8.1%) than SG (−3.3%) (p = 0.0515). No difference was found in median percent weight loss with medications started at weight plateau (−6.0%) versus after weight regain (−5.4%) (p = 0.5304). Patients taking medications at weight loss plateau lost 41.2% of total body weight from before surgery versus 27.1% after weight regain (p = 0.076). Median percent weight change on metformin was −2.9% compared to the rest of the cohort at −7.7% (p = 0.0241). No difference from the rest of the cohort was found for phentermine (p = 0.2018) or topiramate (p = 0.3187). Topiramate, phentermine, and metformin are promising weight loss medications for 21 to 30 year olds. RYGB patients achieve more weight loss on medications but both RYGB and SG benefit. Median total body weight loss from pre-surgical weight may be higher in patients that start medication at postsurgical nadir weight. Participants on metformin lost significantly smaller percentages of weight on medications, which could be the result of underlying medical conditions.

RYGB increases the satiating effect of intrajejunal lipid infusions in female rats

We used a novel rat model to investigate the physiological bases of early satiation after Roux-en-Y gastric bypass surgery (RYGB). Female rats were subjected to RYGB or sham surgery. Chronic infusion catheters were placed in the Roux limb of RYGB rats and the corresponding anatomical locus of the jejuna of sham-RYGB rats. Rats were also ovariectomized and chronically treated with either estradiol (E2; 2 μg each 4th day SC) or the oil vehicle. Testing was begun 10-12 wk after surgery. Intrajejunal lipid infusions (10 min, 4.4 mL, 8.8 kcal) were performed just before test meals of a low-energy artificially sweetened gel diet (0.1 kcal/g) that RYGB rats ingest avidly. Intrajejunal lipid infusions reduced test-meal size more in RYGB rats than sham-operated rats, indicating that, at least after prolonged adaptation to surgery, the satiating actions of lipids acting intra- or post-jejunally are increased by RYGB and that accelerated meal appearance in the intestines after RYGB is not necessary for this effect. The satiating effects of intrajejunal lipid infusions were similar in E2-and oil-treated rats, suggesting that the effect was not dependent on an activational effect of estrogens. In a second experiment, pretreatment with the cholecystokinin A-receptor antagonist devazepide reduced the satiating effect of intrajejunal lipid infusions in E2-treated RYGB rats. Although these data are preliminary due to the smaller numbers of rats than in the first experiment, they suggest that cholecystokinin-mediated jejunal satiation contributes to early satiation after RYGB in ovariectomized rats with peri-ovulatory levels of estradiol. The results of these experiments may be relevant to understanding RYGB outcome in pre- and postmenopausal women.

Food Tolerance and Quality of Alimentation Following Laparoscopic Sleeve Gastrectomy Calibrated with a 50-Fr Bougie: Long-Term Results

BACKGROUND

Adjustable gastric banding and vertical banded gastroplasty are associated with the worst postoperative food tolerance of all bariatric techniques. However, food tolerance tends to improve over time. The aim of this study was to assess food tolerance and diet quality in patients undergoing a sleeve gastrectomy, 1 and 5 years after surgery.

PATIENTS AND METHODS

A prospective observational study of all the morbidly obese patients undergoing laparoscopic sleeve gastrectomy was performed. Food tolerance was assessed using the Quality of Alimentation questionnaire validated in bariatric patients.

RESULTS

Ninety-three patients were analyzed. One year after surgery, mean excess weight loss (EWL) was 81.1% ± 8.3%, and 5 years after surgery, mean EWL was 79.9% ± 6.4%. Preoperatively, 39.8% of patients perceived their eating patterns as good or excellent, 1 year after surgery, 79.6% and 5 years postoperatively, 86%. One year after surgery, the patients reported some difficulty in tolerance of rice, pasta, and red meat. Five years after surgery, these difficulties disappeared and very few patients just refer some tolerance difficulties with red meat. One year after surgery, 10% of the patients reported that they suffered postprandial vomiting often and 22% rarely. Five years postoperatively, only 8% of subjects describe rarely vomiting.

CONCLUSION

After sleeve gastrectomy, the patients recognize an improvement in the quality of alimentation. During the first postoperative year, they present tolerance problems with rice, pasta, and red meat, and that disappeared 5 years after surgery.

Hedonic Changes in Food Choices Following Roux-en-Y Gastric Bypass

It has been suggested that a shift in food choices leading to a diet with a lower energy density plays an important role in successful weight loss after Roux-en-Y gastric bypass (RYGB) surgery. A decreased hedonic drive to consume highly palatable foods may explain these changes in eating behavior. Here, we review the literature examining postoperative changes in mechanisms contributing to hedonic drive (food preferences, reinforcing value of food, dopamine signaling, and activity reward-related brain regions). The majority of studies reviewed support that RYGB decrease the hedonic drive to consume highly palatable foods. Still, in order to fully understand the complexity of these changes, we need studies combining sociological and psychological approaches with objective measures of actual food choices examining different measures of hedonic drive.

Ghrelin, CCK, GLP-1, and PYY(3-36): Secretory Controls and Physiological Roles in Eating and Glycemia in Health, Obesity, and After RYGB

The efficacy of Roux-en-Y gastric-bypass (RYGB) and other bariatric surgeries in the management of obesity and type 2 diabetes mellitus and novel developments in gastrointestinal (GI) endocrinology have renewed interest in the roles of GI hormones in the control of eating, meal-related glycemia, and obesity. Here we review the nutrient-sensing mechanisms that control the secretion of four of these hormones, ghrelin, cholecystokinin (CCK), glucagon-like peptide-1 (GLP-1), and peptide tyrosine tyrosine [PYY(3-36)], and their contributions to the controls of GI motor function, food intake, and meal-related increases in glycemia in healthy-weight and obese persons, as well as in RYGB patients. Their physiological roles as classical endocrine and as locally acting signals are discussed. Gastric emptying, the detection of specific digestive products by small intestinal enteroendocrine cells, and synergistic interactions among different GI loci all contribute to the secretion of ghrelin, CCK, GLP-1, and PYY(3-36). While CCK has been fully established as an endogenous endocrine control of eating in healthy-weight persons, the roles of all four hormones in eating in obese persons and following RYGB are uncertain. Similarly, only GLP-1 clearly contributes to the endocrine control of meal-related glycemia. It is likely that local signaling is involved in these hormones' actions, but methods to determine the physiological status of local signaling effects are lacking. Further research and fresh approaches are required to better understand ghrelin, CCK, GLP-1, and PYY(3-36) physiology; their roles in obesity and bariatric surgery; and their therapeutic potentials.

The utility of weight loss medications after bariatric surgery for weight regain or inadequate weight loss: A multi-center study

BACKGROUND

Patients who undergo bariatric surgery often have inadequate weight loss or weight regain.

OBJECTIVES

We sought to discern the utility of weight loss pharmacotherapy as an adjunct to bariatric surgery in patients with inadequate weight loss or weight regain.

SETTING

Two academic medical centers.

METHODS

We completed a retrospective study to identify patients who had undergone bariatric surgery in the form of a Roux-en-Y gastric bypass (RYGB) or a sleeve gastrectomy from 2000-2014. From this cohort, we identified patients who were placed on weight loss pharmacotherapy postoperatively for inadequate weight loss or weight regain. We extracted key demographic data, medical history, and examined weight loss in response to surgery and after the initiation of weight loss pharmacotherapy.

RESULTS

A total of 319 patients (RYGB = 258; sleeve gastrectomy = 61) met inclusion criteria for analysis. More than half (54%; n = 172) of all study patients lost≥5% (7.2 to 195.2 lbs) of their total weight with medications after surgery. There were several high responders with 30.3% of patients (n = 96) and 15% (n = 49) losing≥10% (16.7 to 195.2 lbs) and≥15% (25 to 195.2 lbs) of their total weight, respectively, Topiramate was the only medication that demonstrated a statistically significant response for weight loss with patients being twice as likely to lose at least 10% of their weight when placed on this medication (odds ratio = 1.9; P = .018). Regardless of the postoperative body mass index, patients who underwent RYGB were significantly more likely to lose≥5% of their total weight with the aid of weight loss medications.

CONCLUSIONS

Weight loss pharmacotherapy serves as a useful adjunct to bariatric surgery in patients with inadequate weight loss or weight regain.

RYGB progressively increases avidity for a low-energy, artificially sweetened diet in female rats

Weight re-gain within 2 y after Roux-en-Y gastric bypass (RYGB) is significantly associated with increased intake of and cravings for sweet foods. Here we describe a novel model of this late increase in sweet appetite. Ovariectomized RYGB and Sham-operated rats, with or without estradiol treatment, were maintained on Ensure liquid diet and offered a low-energy, artificially sweetened diet (ASD) 2 h/d. First, we tested rats more than six months after RYGB. ASD meals were larger in RYGB than Sham rats, whereas Ensure meals were smaller. General physical activity increased during ASD meals in RYGB rats, but not during Ensure meals. Second, new rats were adapted to ASD before surgery, and were then offered ASD again during 4-10 wk following surgery. Estradiol-treated RYGB rats lost the most weight and progressively increased ASD intake to >20 g/2 h in wk 9-10 vs. ∼3 g/2 h in Sham rats. Finally, the same rats were then treated with leptin or saline for 8 d. Leptin did not affect body weight, Ensure intake, or activity during meals, but slightly reduced ASD intake in estradiol-treated RYGB rats. Food-anticipatory activity was increased in estradiol-treated RYGB rats during the saline-injection tests. Because increased meal-related physical activity together with larger meals is evidence of hunger in rats, these data suggest that (1) RYGB can increase hunger for a low-energy sweet food in rats and (2) low leptin levels contribute to this hunger, but are not its only cause. This provides a unique rat model for the increased avidity for sweets that is significantly associated with weight recidivism late after RYGB.

Randomized controlled trial comparing laparoscopic greater curvature plication versus laparoscopic sleeve gastrectomy

BACKGROUND

Laparoscopic greater curvature plication (LGCP) is a new restrictive bariatric procedure, which has a similar restrictive mechanism like laparoscopic sleeve gastrectomy (LSG) without potential risk of leak. Aim of the study was to compare 2-year outcomes of LSG and LGCP.

METHODS

Multicenter prospective randomized trial was started in 2010. A total of 54 patients with morbid obesity were allocated either to LGCP group (n = 25) or LSG group (n = 27). Main exclusion criteria were: ASA > III, age > 75 and BMI > 65 kg/m(2). There were 40 women and 12 men, and the mean age was 42.6 ± 6.8 years (range 35-62). Data on the operation time, complications, hospital stay, body mass index loss, percentage of excess weight loss (%EWL), loss of appetite and improvement in comorbidities were collected during the follow-up examinations.

RESULTS

All procedures were completed laparoscopically. The mean operative time was 92.0 ± 15 min for LSG and 73 ± 19 min for LGCP (p > 0.05). The mean hospital stay was 4.0 ± 1.9 days in the LSG group and 3.8 ± 1.7 days in LGCP group (p > 0.05). One year after surgery, the mean %EWL was 59.5 ± 15.4 % in LSG group and 45.8 ± 17 % in LGCP group (p > 0.05). After 2 years, mean %EWL was 78.9 ± 20 % in the LSG group and 42.4 ± 18 % in the LGCP group (p < 0.01). After 3 years, mean %EWL was 72.8 ± 22 in the LSG group and only 20.5 ± 23.9 in the LGCP group (p < 0.01). Loss of feeling of hunger after 2 years was 25 % in LGCP group and 76.9 % in the LSG group (p < 0.05). The comorbidities including diabetes, sleep apnea and hypertension were markedly improved in the both groups after surgery.

CONCLUSION

The short-term outcomes demonstrated equal effectiveness of the both procedures, but 2-year follow-up showed that LGCP is worse than LSG as a restrictive procedure for weight loss.

Intestinal GLP-1 and satiation: from man to rodents and back

In response to luminal food stimuli during meals, enteroendocrine cells release gastrointestinal (GI) peptides that have long been known to control secretory and motor functions of the gut, pancreas and liver. Glucagon-like peptide-1 (GLP-1) has emerged as one of the most important GI peptides because of a combination of functions not previously ascribed to any other molecule. GLP-1 potentiates glucose-induced insulin secretion, suppresses glucagon release, slows gastric emptying and may serve as a satiation signal, although the physiological status of the latter function has not been fully established yet. Here we review the available evidence for intestinal GLP-1 to fulfill a number of established empirical criteria for assessing whether a hormone inhibits eating by eliciting physiological satiation in man and rodents.

Effect of bariatric surgery on humoral control of metabolic derangements in obese patients with type 2 diabetes mellitus: How it works

Obesity and diabetes is a co-pandemic and a major health concern that is expanding. It has many psychosocial and economic consequences due to morbidity and mortality of this disease combination. The pathophysiology of obesity and related diabetes is complex and multifactorial. One arm of this disease process is the genetic susceptibility. Other arm is dependent on the intricate neuro-humoral factors that converge in the central nerve system. Gut hormones and the adipose tissue derived factors plays an important role in this delicate network. Bariatric surgery provides the only durable option for treatment of obesity and furthermore it provides a remission in the concomitant diseases that accompany obesity. This review provides a brief insight to all these mechanisms and tries to deduce the possible reasons of remission of type 2 diabetes after bariatric surgery.

Food tolerance and diet quality following adjustable gastric banding, sleeve gastrectomy and Roux-en-Y gastric bypass

OBJECTIVE

The effects of food tolerance (if any) on diet quality several years post-surgery remain unclear. Our study aimed to assess food tolerance and diet quality after three bariatric procedures; adjustable gastric banding (AGB), sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGBP), 2â??4 years post-surgery.

METHODS

This prospective, cross-sectional study assessed weight loss, food tolerance and diet quality in 130 subjects (14 obese pre-surgical controls, 13 AGB, 62 SG and 41 RYGBP). Inclusion criteria selected patients who underwent bariatric surgery between 1 January 2007 and 31 December 2008, at a single bariatric clinic. Non-parametric tests (Kruksalâ??Wallis and Mannâ??Whitney) along with Spearman's correlation coefficient analysis were used.

RESULTS

Superior food tolerance was reported by the control (24.5), SG (24.0) and RYGBP (22.0) groups, compared with the AGB group (15.5; P < 0.001). The control and AGB groups consumed significantly more high-calorie extra foods (9.2 and 7.7 daily serves respectively) compared with the SG (3.4 serves) and RYGBP (4.0 serves) groups. There were several significant correlations between food tolerance and dietary intake including breads and cereals and meat and meat alternatives.

CONCLUSION

The control and AGB groups consumed significantly more high-calorie extra foods, a result that was paralleled by poor weight loss and food tolerance outcomes for the AGB group. A significant positive relationship between food tolerance and diet quality was established. Poor food tolerance and thus compromised diet quality need to be considered as post-surgical complications of the AGB procedure.

Could the improvement of obesity-related co-morbidities depend on modified gut hormones secretion?

Obesity and its associated diseases are a worldwide epidemic disease. Usual weight loss cures - as diets, physical activity, behavior therapy and pharmacotherapy - have been continuously implemented but still have relatively poor long-term success and mainly scarce adherence. Bariatric surgery is to date the most effective long term treatment for morbid obesity and it has been proven to reduce obesity-related co-morbidities, among them nonalcoholic fatty liver disease, and mortality. This article summarizes such variations in gut hormones following the current metabolic surgery procedures. The profile of gut hormonal changes after bariatric surgery represents a strategy for the individuation of the most performing surgical procedures to achieve clinical results. About this topic, experts suggest that the individuation of the crosslink among the gut hormones, microbiome, the obesity and the bariatric surgery could lead to new and more specific therapeutic interventions for severe obesity and its co-morbidities, also non surgical.

Effects of PYY3-36 and GLP-1 on energy intake, energy expenditure, and appetite in overweight men

Our aim was to examine the effects of GLP-1 and PYY3-36, separately and in combination, on energy intake, energy expenditure, appetite sensations, glucose and fat metabolism, ghrelin, and vital signs in healthy overweight men. Twenty-five healthy male subjects participated in this randomized, double-blinded, placebo-controlled, four-arm crossover study (BMI 29 ± 3 kg/m(2), age 33 ± 9 yr). On separate days they received a 150-min intravenous infusion of 1) 0.8 pmol·kg(-1)·min(-1) PYY3-36, 2) 1.0 pmol·kg(-1)·min(-1) GLP-1, 3) GLP-1 + PYY3-36, or 4) placebo. Ad libitum energy intake was assessed during the final 30 min. Measurements of appetite sensations, energy expenditure and fat oxidation, vital signs, and blood variables were collected throughout the infusion period. No effect on energy intake was found after monoinfusions of PYY3-36 (-4.2 ± 4.8%, P = 0.8) or GLP-1 (-3.0 ± 4.5%, P = 0.9). However, the coinfusion reduced energy intake compared with placebo (-30.4 ± 6.5%, P < 0.0001) and more than the sum of the monoinfusions (P < 0.001), demonstrating a synergistic effect. Coinfusion slightly increased sensation of nausea (P < 0.05), but this effect could not explain the effect on energy intake. A decrease in plasma ghrelin was found after all treatments compared with placebo (all P < 0.05); however, infusions of GLP-1 + PYY3-36 resulted in an additional decrease compared with the monoinfusions (both P < 0.01). We conclude that coinfusion of GLP-1 and PYY3-36 exerted a synergistic effect on energy intake. The satiating effect of the meal was enhanced by GLP-1 and PYY3-36 in combination compared with placebo. Coinfusion was accompanied by slightly increased nausea and a decrease in plasma ghrelin, but neither of these factors could explain the reduction in energy intake.

The impact of laparoscopic sleeve gastrectomy on plasma ghrelin levels: a systematic review

Within the last decade, several authors have proposed laparoscopic sleeve gastrectomy (LSG) as a potential definitive treatment for morbid obesity. While initially perceived as being a solely restrictive procedure, it is now theorized to have additional hormonal effects (primarily the reduction of circulating levels of plasma ghrelin). However, there is limited supporting evidence for this claim. Therefore, the purpose of our study is to conduct a systematic review of the literature to clarify the effects of LSG on modulation of postoperative ghrelin concentrations. A comprehensive literature search for published or unpublished studies of sleeve gastrectomy (SG) and ghrelin written in English prior to February 2013 was performed using Pubmed, EMBASE, the Cochrane database, and Scopus. Gray literature was also searched through Google. Inclusion criteria for searches were: randomized controlled trials, non-randomized clinical trials, retrospective and prospective cohort studies, or case series. Seven studies were deemed suitable for analysis. The mean patient age was 43 ± 8.8 years and female percentage was 74.4 ± 15.3 %. The mean initial BMI was 46.2 ± 7.8 and mean follow-up time was 9.5 ± 15 months. The mean postoperative BMI was 37.3 ± 5.8 over the same follow-up period. Pooled mean preoperative ghrelin levels were 698.4 ± 312.4 pg/ml and postoperative levels were 414.1 ± 226.3 pg/ml (P < 0.0001). Pooled analysis of ghrelin levels at 3, 6, and 12 months showed a significant reduction in circulating levels. Our systematic review shows that LSG has a significant effect on ghrelin levels, leading to considerable reduction in circulation levels following surgery. Further research and standardization is necessary to clearly establish a causative relationship between LSG and reduction of circulating ghrelin levels.

Metabolic surgery for type 2 diabetes with BMI <35 kg/m(2) : an endocrinologist's perspective

Is bariatric surgery as primary therapy for type 2 diabetes mellitus (T2DM) with body mass index (BMI) <35 kg/m² justified? Open-label studies have shown that bariatric surgery causes remission of diabetes in some patients with BMI <35 kg/m². All such patients treated had substantial weight loss. Diabetes remission was less likely in patients with lower BMI than those with higher BMI, in patients with longer than shorter duration and in patients with lesser than greater insulin reserve. Relapse of diabetes increases with time after surgery and weight regain. Deficiencies of data are lack of randomized long-term studies comparing risk/benefit of bariatric surgery to contemporary intensive medical therapy. Current data do not justify bariatric surgery as primary therapy for T2DM with BMI <35 kg/m².

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.

The role of hormonal factors in weight loss and recidivism after bariatric surgery

Substantial heterogeneity exists in weight loss trajectories amongst patients following bariatric surgery. Hormonal factors are postulated to be amongst the contributors to the variation seen. Several hormones involved in hunger, satiety, and energy balance are affected by bariatric surgery, with the alteration in hormonal milieu varying by procedure. Limited research has been conducted to examine potential hormonal mediators of weight loss failure or recidivism following bariatric surgery. While hormonal factors that influence weight loss success following gastric banding have not been identified, data suggest that hormonal factors may be involved in modulating weight loss success following gastric bypass. There may be hormonal mediators involved in determining the weight trajectory following sleeve gastrectomy, though the extremely limited data currently available prohibits definitive conclusions from being drawn. There is great need for future research studies to explore this knowledge gap, as improving this knowledge base could be of benefit to guide clinicians toward understanding the hormonal contributors to a patient's postoperative weight loss failure or recidivism or perhaps be of value in selecting the most appropriate bariatric procedure based on the preoperative hormone milieu. Integrative interdisciplinary approaches exploring these complex interrelationships could potentially increase the explanatory power of such investigations.

Effects of RYGB on energy expenditure, appetite and glycaemic control: a randomized controlled clinical trial

OBJECTIVES

Increased energy expenditure (EE) has been proposed as an important mechanism for weight loss following Roux-en-Y gastric bypass (RYGB). However, this has never been investigated in a controlled setting independent of changes in energy balance. Similarly, only few studies have investigated the effect of RYGB on glycaemic control per se. Here, we investigated the effect of RYGB on EE, appetite, glycaemic control and specific signalling molecules compared with a control group in comparable negative energy balance.

SUBJECTS/METHODS

Obese normal glucose-tolerant participants were randomized to receive RYGB after 8 (n=14) or 12 weeks (n=14). The protocol included a visit at week 0 and three visits (weeks 7, 11 and 78) where 24-h EE, appetite and blood parameters were assessed. Participants followed a low-calorie diet from weeks 0-11, with those operated at week 12 serving as a control group for those operated at week 8.

RESULTS

Compared with controls, RYGB-operated participants had lower body composition-adjusted 24-h EE and basal EE 3 weeks postoperatively (both P<0.05) but EE parameters at week 78 were not different from preoperative values (week 7). Surgery changed the postprandial response of glucagon-like peptide-1 (GLP-1), peptide YY3-36 (PYY), ghrelin, cholecystokinin, fibroblast growth factor-19 and bile acids (all P<0.05). Particularly, increases in GLP-1, PYY and decreases in ghrelin were associated with decreased appetite. None of HOMA-IR (homeostasis model assessment-estimated insulin resistance), Matsuda index, the insulinogenic index, the disposition index and fasting hepatic insulin clearance were different between the groups, but RYGB operated had lower fasting glucose (P<0.05) and the postprandial glucose profile was shifted to the left (P<0.01).

CONCLUSIONS

Our data do not support that EE is increased after RYGB. More likely, RYGB promotes weight loss by reducing appetite, partly mediated by changes in gastrointestinal hormone secretion. Furthermore, we found that the early changes in glycaemic control after RYGB is to a large extent mediated by caloric restriction.

Fasting plasma triglycerides predict the glycaemic response to treatment of type 2 diabetes by gastric electrical stimulation. A novel lipotoxicity paradigm

BACKGROUND

Non-stimulatory, meal-mediated electrical stimulation of the stomach (TANTALUS-DIAMOND) improves glycaemic control and causes modest weight loss in patients with Type 2 diabetes who are inadequately controlled on oral anti-diabetic medications. The magnitude of the glycaemic response in clinical studies has been variable. A preliminary analysis of data from patients who had completed 6 months of treatment indicated that the glycaemic response to the electrical stimulation was inversely related to the baseline fasting plasma triglyceride level.

METHOD

An analysis of 40 patients who had had detailed longitudinal studies for 12 months.

RESULTS

Twenty-two patients with fasting plasma triglycerides ≤ 1.7 mmol/l had mean decreases in HbA1c after 3, 6 and 12 months of gastric contraction modulation treatment of -15 ± 2.1 mmol/mol (-1.39 ± 0.20%), -16 ± 2.2 mmol/mol (-1.48 ± 0.20%) and -14 ± 3.0 mmol/mol (-1.31 ± 0.26%), respectively. In contrast, 18 patients with fasting plasma triglyceride > 1.7 mmol/l had mean decreases in HbA1c of -7 ± 1.7 mmol/mol (-0.66 ± 0.16%), -5 ± 1.6 mmol/mol (-0.44 ± 0.18%) and -5 ± 1.7 mmol/mol (-0.42 ± 0.16%), respectively. Pearson's correlation coefficient between fasting plasma triglyceride and decreases in HbA1c at 12 months of treatment was 0.34 (P < 0.05). Homeostasis model assessment of insulin resistance was unchanged during 12 months of treatment in patients with high baseline fasting triglycerides, while it progressively improved in patients with low fasting plasma triglycerides. Patients with low fasting plasma triglycerides had a tendency to lose more weight than those with high fasting plasma triglycerides, but this did not achieve statistical significance.

CONCLUSIONS

The data presented suggest the existence of a triglyceride lipotoxic mechanism that interferes with gastric/neural mediated pathways that can regulate glycaemic control in patients with type 2 diabetes. The data suggest the existence of a triglyceride lipotoxic pathway that interferes with gastric/neural mediated pathways that can regulate glycaemic control.

Sleeve gastrectomy and Roux-en-Y gastric bypass are equally effective in correcting insulin resistance

BACKGROUND

Laparoscopic Roux-en-Y gastric bypass (LRYGB) and laparoscopic sleeve gastrectomy (LSG) are associated with glucose metabolism improvement although data on insulin resistance remission rates after these procedures are lacking.

AIMS

Primary aim was to compare insulin resistance remission rates achieved after LRYGB and LSG, using population-specific HOMA-IR cut-off points. Secondary objectives were to analyze factors associated with type 2 diabetes mellitus (T2DM) complete remission according to the new American Diabetes Association criteria and to examine changes in HOMA-B during follow-up.

METHODS

Non-randomized, prospective cohort study of patients undergoing LRYGB or LSG with a minimal follow-up of 24 months. Patients on insulin therapy were excluded.

RESULTS

At baseline, 56 (48.7%) of the 115 LRYGB group and 48 (61.5%) of the 78 LSG group had insulin resistance, and 29 (25.2%) and 20 (25.6%) T2DM, respectively. No differences were detected in insulin resistance remission rate (92.9% LRYGB and 87.5% LSG, p = 0.355) nor in T2DM complete remission at 2 years (62.1 vs 60% respectively, p = 0.992). Factors independently associated with T2DM complete remission were diabetes treatment and a greater decrease in 3-month HOMA-IR index. The HOMA-B index showed a progressive decline during follow-up.

CONCLUSION

Both surgical techniques are equally effective in achieving insulin resistance normalization in the majority of severely obese patients. Three-month HOMA-IR reduction after surgery was the main predictor of T2DM complete remission.

Insulin resistance and bariatric surgery

The objective of this article is to systematically review the changes in insulin resistance after various types of bariatric surgical procedures. A Pubmed and EMBASE search for studies measuring insulin resistance before and after bariatric surgery was done and all original research articles from 1980 to present (2011) were included. Only the currently widely performed bariatric procedures were included. A meta-analysis of change in HOMA-IR was conducted, grouping studies with similar duration of follow-up. The percentage decrease in HOMA-IR at <=2 weeks, 1 month, 3 months, 6 months, 12 months and >16-18 months was found to be (mean ± standard error) -33.48 ± 5.78, -46.43 ± 6.99, -38.79 ± 9.64, -58.62 ± 7.38, -44.91 ± 7.98 and -67.04 ± 10.78%, respectively. RYGB (gastric bypass) and BPD (biliopancreatic diversion) produced a significant decrease in insulin resistance at 2 weeks after surgery, while LSG (sleeve gastrectomy) was strongly trending. LSG produced an earlier decrease in insulin resistance when compared to LAGB (gastric banding). RYGB, BPD and LSG produce an early decrease in insulin resistance through yet unknown mechanisms.

Central nervous system mechanisms linking the consumption of palatable high-fat diets to the defense of greater adiposity

The central nervous system (CNS) plays key role in the homeostatic regulation of body weight. Satiation and adiposity signals, providing acute and chronic information about available fuel, are produced in the periphery and act in the brain to influence energy intake and expenditure, resulting in the maintenance of stable adiposity. Diet-induced obesity (DIO) does not result from a failure of these central homeostatic circuits. Rather, the threshold for defended adiposity is increased in environments providing ubiquitous access to palatable, high-fat foods, making it difficult to achieve and maintain weight loss. Consequently, mechanisms by which nutritional environments interact with central homeostatic circuits to influence the threshold for defended adiposity represent critical targets for therapeutic intervention.

Metabolic surgery-principles and current concepts

INTRODUCTION

In the almost six decades of bariatric surgery, a variety of surgical approaches to treating morbid obesity have been developed.

HISTORY AND EVOLUTION

Rather than prior techniques being continually superseded by new ones, a broad choice of surgical solutions based on restrictive, malabsorptive, humoral effects, or combinations thereof, is now available. In fact, in recent years, the advent of surgically modifying human metabolism promises new approaches to ameliorate traditionally medically treated metabolic entities, i.e., diabetes, even in the non-obese. The understanding of the various metabolic effects have led to a paradigm shift from bariatric surgery as a solely weight-reducing procedure to metabolic surgery affecting whole body metabolism.

CONCLUSION

The bariatric surgeon now faces the challenge and opportunity of selecting the most suitable technique for each individual case. To assist in such decision-making, this review, Metabolic surgery-principles and current concepts, is presented, tracing the historical development; describing the various surgical techniques; elucidating the mechanisms by which glycemic control can be achieved that involve favorable changes in insulin secretion and insulin sensitivity, gut hormones, adipokines, energy expenditure, appetite, and preference for low glycemic index foods; as well as exploring the fascinating future potential of this new interdisciplinary field.