Changes in Gastrointestinal Hormone Responses, Insulin Sensitivity, and Beta-Cell Function Within 2 Weeks After Gastric Bypass in Non-diabetic Subjects

Glucagon-like peptide 1 (GLP-1) drives postprandial hyperinsulinemic hypoglycemia in pregnant women with a history of Roux-en-Y gastric bypass operation

BACKGROUND

The influential role of incretin hormones on glucose metabolism in patients with a history of Roux-en-Y gastric bypass (RYGB) has been investigated thoroughly, but there has been little examination of the effect of incretins and ectopic lipids on altered glucose profiles, especially severe hypoglycemia in pregnant women with RYGB.

METHODS

In this prospective clinical study, an oral glucose tolerance test (OGTT), an intravenous glucose tolerance test (IVGTT), and continuous glucose monitoring (CGM) were conducted in 25 women with RYGB during pregnancy, 19 of normal weight (NW) and 19 with obesity (OB) between the 24th and the 28th weeks of pregnancy, and 3 to 6 months post-partum. Post-partum, the ectopic lipid content in the liver, heart, and skeletal muscle was analyzed using ¹H-magnetic resonance spectroscopy (¹H-MRS).

RESULTS

RYGB patients presented with major fluctuations in glucose profiles, including a high occurrence of postprandial hyperglycemic spikes and hypoglycemic events during the day, as well as a high risk of hypoglycemic periods during the night (2.9 ± 1.1% vs. 0.1 ± 0.2% in the OB and vs. 0.8 ± 0.6% in the NW groups, p < 0.001). During the extended OGTT, RYGB patients presented with exaggerated expression of GLP-1, which was the main driver of the exaggerated risk of postprandial hypoglycemia in a time-lagged correlation analysis. Basal and dynamic GLP-1 levels were not related to insulin sensitivity, insulin secretion, or beta cell function and did not differ between pregnant women with and without GDM. A lower amount of liver fat (2.34 ± 5.22% vs.5.68 ± 4.42%, p = 0.015), which was positively related to insulin resistance (homeostasis model assessment of insulin resistance, HOMA-IR: rho = 0.61, p = 0.002) and beta-cell function (insulinogenic index: rho = 0.65, p = 0.001), was observed in the RYGB group after delivery in comparison to the OB group.

CONCLUSION

GLP-1 is mainly involved in the regulation of postprandial glucose metabolism and therefore especially in the development of postprandial hypoglycemia in pregnant RYGB patients, who are characterized by major alterations in glucose profiles, and thus in long-term regulation, multiple organ-related mechanisms, such as the lipid content in the liver, must be involved.

Anti-Obesity Therapy: from Rainbow Pills to Polyagonists

With their ever-growing prevalence, obesity and diabetes represent major health threats of our society. Based on estimations by the World Health Organization, approximately 300 million people will be obese in 2035. In 2015 alone there were more than 1.6 million fatalities attributable to hyperglycemia and diabetes. In addition, treatment of these diseases places an enormous burden on our health care system. As a result, the development of pharmacotherapies to tackle this life-threatening pandemic is of utmost importance. Since the beginning of the 19th century, a variety of drugs have been evaluated for their ability to decrease body weight and/or to improve deranged glycemic control. The list of evaluated drugs includes, among many others, sheep-derived thyroid extracts, mitochondrial uncouplers, amphetamines, serotonergics, lipase inhibitors, and a variety of hormones produced and secreted by the gastrointestinal tract or adipose tissue. Unfortunately, when used as a single hormone therapy, most of these drugs are underwhelming in their efficacy or safety, and placebo-subtracted weight loss attributed to such therapy is typically not more than 10%. In 2009, the generation of a single molecule with agonism at the receptors for glucagon and the glucagon-like peptide 1 broke new ground in obesity pharmacology. This molecule combined the beneficial anorectic and glycemic effects of glucagon-like peptide 1 with the thermogenic effect of glucagon into a single molecule with enhanced potency and sustained action. Several other unimolecular dual agonists have subsequently been developed, and, based on their preclinical success, these molecules illuminate the path to a new and more fruitful era in obesity pharmacology. In this review, we focus on the historical pharmacological approaches to treat obesity and glucose intolerance and describe how the knowledge obtained by these studies led to the discovery of unimolecular polypharmacology.

Metabolic and Endocrine Consequences of Bariatric Surgery

Obesity is one of the most serious worldwide epidemics of the twenty-first century according to the World Health Organization. Frequently associated with a number of comorbidities, obesity threatens and compromises individual health and quality of life. Bariatric surgery (BS) has been demonstrated to be an effective treatment to achieve not only sustained weight loss but also significant metabolic improvement that goes beyond mere weight loss. The beneficial effects of BS on metabolic traits are so widely recognized that some authors have proposed BS as metabolic surgery that could be prescribed even for moderate obesity. However, most of the BS procedures imply malabsorption and/or gastric acid reduction which lead to nutrient deficiency and, consequently, further complications could be developed in the long term. In fact, BS not only affects metabolic homeostasis but also has pronounced effects on endocrine systems other than those exclusively involved in metabolic function. The somatotropic, corticotropic, and gonadal axes as well as bone health have also been shown to be affected by the various BS procedures. Accordingly, further consequences and complications of BS in the long term in systems other than metabolic system need to be addressed in large cohorts, taking into account each bariatric procedure before making generalized recommendations for BS. In this review, current data regarding these issues are summarized, paying special attention to the somatotropic, corticotropic, gonadal axes, and bone post-operative health.

Extrapancreatic glucagon: Present status

Pancreatic alpha cells are generally considered the only source of glucagon secretion in humans. In the 1970s several groups investigating totally pancreatectomised animals reported that glucagon-like immunoreactive material could be detected in the gastrointestinal tract and reopened the question of an extrapancreatic source of glucagon proposed in 1948 when a hyperglycaemic substance was found in the gastrointestinal tract of dogs and rabbits. Nevertheless, over the years, controversy about the existence of extrapancreatic glucagon has flourished as it proved difficult to accurately measure fully processed 29-amino acid glucagon. Recent advances in analytical methods have increased sensitivity and specificity of glucagon assays and, furthermore, technical advances in mass spectrometry-based proteomics have made the detection of low-abundant peptides, such as glucagon, in human plasma more accurate. Here we review new data on extrapancreatic glucagon secretion in the context of historical data and recent analytical breakthroughs. Furthermore, the source, regulation and potential physiological role of extrapancreatic glucagon are discussed and ongoing challenges and knowledge-gaps are outlined.

Diabesity and mood disorders: Multiple links through the microbiota-gut-brain axis

The global prevalence of diabesity is on the rise, and the clinical, social and economic health burden arising from this epidemic is aggravated by a significant co-morbidity of diabesity with neuropsychiatric disease, particularly depression. Importantly, not only is the prevalence of mood disorders elevated in patients with type 2 diabetes, depressed patients are also more prone to develop diabetes. This reciprocal relationship calls for a molecular and systemic analysis of diabesity-brain interactions to guide preventive and therapeutic strategies. The analysis we are presenting in this review is modelled on the microbiota-gut-brain axis, which provides the brain with information from the gut not only via the nervous system, but also via a continuous stream of microbial, endocrine, metabolic and immune messages. This communication network offers important clues as to how obesity and diabetes could target the brain to provoke neuropsychiatric disease. There is emerging evidence that the gut microbiota is orchestrating a multiplicity of bodily functions that are intimately related to the immune, metabolic and nervous systems and that gut dysbiosis spoils the homeostasis between these systems. In our article we highlight two groups of molecular links that seem to have a significant bearing on the impact of diabesity on the brain. On the one hand, we focus on microbiota-related metabolites such as short-chain fatty acids, tryptophan metabolites, immune stimulants and endocannabinoids that are likely to play a mediator role. On the other hand, we discuss signalling molecules that operate primarily in the brain, specifically neuropeptide Y, brain-derived neurotrophic factor and γ-amino butyric acid, that are disturbed by microbial factors, obesity and diabetes and are relevant to mental illness. Finally, we address the usefulness of diet-related interventions to suspend the deleterious relationship between diabesity and mood disorders.

Glucose Metabolism Parameters and Post-Prandial GLP-1 and GLP-2 Release Largely Vary in Several Distinct Situations: a Controlled Comparison Among Individuals with Crohn's Disease and Individuals with Obesity Before and After Bariatric Surgery

BACKGROUND

This study aims to compare the post-prandial curves of glucose, insulin, GLP-1, and GLP-2 among individuals with Crohn's disease (CD), obese individuals before and after bariatric surgery, and healthy controls.

METHODS

This an exploratory cross-sectional study that involved five groups of patients (two groups of individuals with CD-active and inactive), bariatric patients (pre- and post-surgery, who were their own controls), and a distinct separated control group of healthy volunteers. C-reactive protein (CRP) levels and the post-prandial curves of glucose, insulin, GLP-1, and GLP-2 curves were assessed and compared.

RESULTS

The pre-RYGB group presented significantly higher levels of CRP than the post-RYGB (p = 0.001) and the control group (p = 0.001). The inactive CD group presented a higher post-prandial GLP-1 area under the curve (AUC) than the pre-RYGB group (p = 0.009). The post-RYGB group presented significantly higher AUCs of GLP-2 than the pre-RYGB group (p < 0.0001), both inactive and active CD groups (p < 0.0001 in both situations), and the control group (p = 0.002). The pre-RYGB group presented a significantly higher AUC of glucose than the post-RYGB (p = 0.02) and both active and inactive CD groups (p = 0.019 and p = 0.046, respectively). The pre-RYGB group presented a significantly higher AUC of insulin than the control (p = 0.005) and both CD groups (p < 0.0001).

CONCLUSIONS

Obesity is associated with an inflammatory state comparable to the one observed in CD; inflammation may also be enrolled in the blockade of GLP-2. CD individuals present a more incretin-driven pattern of glucose metabolism, as a way to prevent hypoglycemia and compensate the carbohydrate malabsorption and GLP-2 blockade.

Association of circulating proinflammatory marker, leucine-rich-α2-glycoprotein (LRG1), following metabolic/bariatric surgery

BACKGROUND

Obesity confers substantial excess risk for morbidity and mortality, especially for type 2 diabetes (T2D). Leucine-rich-α2-glycoprotein 1 (LRG1), a novel proinflammatory factor, was recently reported to be higher in patients with T2D with complications of peripheral arterial disease. Association of LRG1, obesity, and weight loss is unknown. We examined whether plasma LRG1 is associated with obesity in health screening participants and if it predicts future weight loss in morbidly obese patients after metabolic/bariatric surgery.

METHODS

Cohort 1 was a cross-sectional study from a Health Screening program (n = 616) in a tertiary hospital. Cohort 2 was a prospective study of morbidly obese patients (n = 231) who underwent metabolic/bariatric surgery with follow-up weight measurements. Anthropometric data, baseline fasting glucose, plasma adiponectin, high sensitivity C-reactive protein (HsCRP), and LRG1 were measured. Postsurgery blood, after metabolic/bariatric surgery, were available for LRG1and HsCRP measurements in 57 patients.

RESULTS

In the group with highest tertile of LRG1, body mass index (BMI), waist circumference, and HsCRP were significantly higher, while total cholesterol, high-density lipoprotein, low-density lipoprotein, and adiponectin were lower than tertiles 1 and 2. Generalized linear model analysis showed that female gender (P < .0001), non-Chinese ethnicity (P < .019), and higher HsCRP (P < .0001) levels were independent and significant determinants of higher plasma LRG1 levels. After adjustment for age, gender, ethnicity, and baseline BMI, female gender (P = .020), higher presurgery BMI (P = .001), and lower presurgery LRG1 (P = .002) remained statistically significant predictors for greater weight loss. Plasma LRG1 increased significantly [from 28.2 (21.9-36.8) to 34.9 (22.6-49.5)] μg/mL (P = .003) within 1.5 months, after metabolic/bariatric surgery.

CONCLUSIONS

Our study demonstrates that LRG1 level is positively associated with obesity and a lower level of plasma LRG1 predicts weight loss in metabolic/bariatric surgery. Our novel findings suggest LRG1, itself or in combination with other known factors, is a potential biomarker of inflammation and obesity.

Gut adaptation after metabolic surgery and its influences on the brain, liver and cancer

Metabolic surgery is the best treatment for long-term weight loss maintenance and comorbidity control. Metabolic operations were originally intended to change anatomy to alter behaviour, but we now understand that the anatomical changes can modulate physiology to change behaviour. They are no longer considered only mechanically restrictive and/or malabsorptive procedures; rather, they are considered metabolic procedures involving complex physiological changes, whereby gut adaptation influences signalling pathways in several other organs, including the liver and the brain, regulating hunger, satiation, satiety, body weight, glucose metabolism and immune functions. The integrative physiology of gut adaptation after these operations consists of a complex mechanistic web of communication between gut hormones, bile acids, gut microbiota, the brain and both enteric and central nervous systems. The understanding of nutrient sensing via enteroendocrine cells, the enteric nervous system, hypothalamic peptides and adipose tissue and of the role of inflammation has advanced our knowledge of this integrative physiology. In this Review, we focus on the adaptation of gut physiology to the anatomical alterations from Roux-en-Y gastric bypass and vertical sleeve gastrectomy and the influence of these procedures on food intake, weight loss, nonalcoholic fatty liver disease (NAFLD) and cancer. We also aim to demonstrate the underlying mechanisms that could explain how metabolic surgery could be used as a therapeutic option in NAFLD and certain obesity-related cancers.

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.

On the relationship between glucose absorption and glucose-stimulated secretion of GLP-1, neurotensin, and PYY from different intestinal segments in the rat

Ingested glucose powerfully stimulates the secretion of appetite‐ and metabolism‐regulating peptide hormones from the gut – including glucagon‐like peptide‐1 (GLP‐1), neurotensin (NT), and polypeptide YY (PYY). However, the regional origin of these secretions after glucose stimulation is not well characterized, and it remains uncertain how their secretion is related to glucose absorption. We isolated and perfused either the upper (USI) or the lower (LSI) small intestine or the colon from rats and investigated concomitant glucose absorption and secretory profiles of GLP‐1, NT, and PYY. In the USI and LSI luminal glucose (20%, w/v) increased GLP‐1 and NT secretion five to eightfold compared to basal secretion. Compared to the USI, basal and stimulated GLP‐1 secretion from the colon was 8–10 times lower and no NT secretion was detected. Luminal glucose stimulated secretion of PYY four to fivefold from the LSI and from the USI and colon, but the responses in the USI and colon were 5‐ to 15‐fold lower than in the LSI. Glucose was absorbed to a comparable extent in the USI and LSI by mechanisms that partly depended on both SGLT1 and GLUT2 activity, whereas the absorption in the colon was 80–90% lower. The absorption rates were, however, similar when adjusted for segmental length. Glucose absorption rates and NT, PYY and in particular GLP‐1 secretion were strongly correlated (P < 0.05). Our results indicate that the rate of secretion of GLP‐1, NT, and PYY in response to glucose, regardless of the involved molecular machinery, is predominantly regulated by the rate of glucose absorption.

Roux-en-Y gastric bypass compared with equivalent diet restriction: Mechanistic insights into diabetes remission

AIMS

To investigate the physiological mechanisms leading to rapid improvement in diabetes after Roux-en-Y gastric bypass (RYGB) and specifically the contribution of the concurrent peri-operative dietary restrictions, which may also alter glucose metabolism.

MATERIALS AND METHODS

In order to assess the differential contributions of diet and surgery to the mechanisms leading to the rapid improvement in diabetes after RYGB we enrolled 10 patients with type 2 diabetes scheduled to undergo RYGB. All patients underwent a 10-day inpatient supervised dietary intervention equivalent to the peri-operative diet (diet-only period), followed by, after a re-equilibration (washout) period, an identical period of pair-matched diet in conjunction with RYGB (diet and RYGB period). We conducted extensive metabolic assessments during a 6-hour mixed-meal challenge test, with stable isotope glucose tracer infusion performed before and after each intervention.

RESULTS

Similar improvements in glucose levels, β-cell function, insulin sensitivity and post-meal hepatic insulin resistance were observed with both interventions. Both interventions led to significant reductions in fasting and postprandial acyl ghrelin. The diet-only intervention induced greater improvements in basal hepatic glucose output and post-meal gastric inhibitory polypeptide (GIP) secretion. The diet and RYGB intervention induced significantly greater increases in post-meal glucagon-like peptide-1 (GLP-1), peptide YY (PYY) and glucagon levels.

CONCLUSIONS

Strict peri-operative dietary restriction is a main contributor to the rapid improvement in glucose metabolism after RYGB. The RYGB-induced changes in the incretin hormones GLP-1 and PYY probably play a major role in long-term compliance with such major dietary restrictions through central and peripheral mechanisms.

MEDI0382, a GLP-1 and glucagon receptor dual agonist, in obese or overweight patients with type 2 diabetes: a randomised, controlled, double-blind, ascending dose and phase 2a study

BACKGROUND

Weight loss is often key in the management of obese or overweight patients with type 2 diabetes, yet few treatments for diabetes achieve clinically meaningful weight loss. We aimed to assess the efficacy, tolerability, and safety of treatment with MEDI0382, a balanced glucagon-like peptide-1 and glucagon receptor dual agonist developed to provide glycaemic control and weight loss, in patients with type 2 diabetes.

METHODS

This randomised, placebo-controlled, double-blind, combined multiple-ascending dose (MAD) and phase 2a study was done at 11 study sites (hospitals and contract research organisations) in Germany. We enrolled patients aged 18-65 years with controlled type 2 diabetes (glycated haemoglobin A_1c [HbA_1c] levels of 6·5-8·5% at screening) and a body-mass index between 27 kg/m² and 40 kg/m². An interactive web-response system was used to randomly assign patients to receive MEDI0382 or placebo. Patients were randomly assigned 2:1 in cohorts A-C and 3:1 in cohorts D and E in the MAD portion of the study, and 1:1 in the phase 2a portion. Randomisation was done by a contracted third-party operator who was not involved in the clinical operations of the study. The pharmacists, participants, and study site personnel involved in treating and assessing participants were masked to treatment allocation. Patients received once-daily subcutaneous injections of the study drug at doses of no more than 300 μg for 22 days or less in the MAD portion of the study, and a dose of no more than 200 μg for 41 days or less in the phase 2a portion. The two primary endpoints of the phase 2a portion were the change from baseline to day 41 in glucose area under the curve at 0-4 h (AUC_{0-4 h}) after a mixed-meal tolerance test (MMTT), assessed in all participants who received at least one dose of study drug and whose measurements were taken at baseline and day 41, and change from baseline in bodyweight, assessed in the intention-to-treat (ITT) population. Safety analyses were done in all participants who received any study drug analysed according to the treatment they received. This study is registered with ClinicalTrials.gov, number NCT02548585.

FINDINGS

Patients were recruited between Dec 9, 2015, and Feb 24, 2017. 61 patients were randomly assigned to the MAD part of the study (42 to MEDI0382 and 19 to placebo). 51 patients were randomly assigned to the phase 2a part, of whom 25 were randomly assigned to MEDI0382 and 26 to placebo. In the phase 2a study, three patients in the MEDI0382 group and one in the placebo group discontinued, all as a result of adverse events. 22 (88%) patients in the MEDI0382 group and 25 (96%) in the placebo group received at least one dose and had measurements taken at baseline and day 41. Glucose AUC_{0-4 h} post MMTT decreased significantly with MEDI0382 versus placebo (least squares [LS] mean -32·78% [90% CI -36·98 to -28·57] vs -10·16% [-14·10 to -6·21], and the mean difference was -22·62% [-28·40 to -16·85]; p<0·0001). In the ITT population, reduction in bodyweight was significantly greater with MEDI0382 than with placebo (LS mean -3·84 kg [90% CI -4·55 to -3·12] vs -1·70 kg [-2·40 to -1·01] and mean difference of 2·14 kg [-3·13 to -1·31]; p=0·0008). The proportion of patients who had a treatment-emergent adverse event (TEAE) was similar between treatment groups (22 [88%] of 25 in the MEDI0382 group vs 23 [88%] of 26 in the placebo group); gastrointestinal disorders (18 [72%] vs 13 [40%]) and decreased appetite (five [20%] vs none) occurred more frequently with MEDI0382 than placebo. No participants in the MEDI0382 group had a grade 3 or worse TEAE (vs two [8%] in the placebo group).

INTERPRETATION

MEDI0382 has the potential to deliver clinically meaningful reductions in blood glucose and bodyweight in obese or overweight individuals with type 2 diabetes.

FUNDING

MedImmune.

Effect of laparoscopic Roux-en-Y gastric bypass versus laparoscopic sleeve gastrectomy on fasting gastrointestinal and pancreatic peptide hormones: A prospective nonrandomized trial

BACKGROUND

Changes in gastrointestinal and pancreatic hormones may play a role in promoting long-term weight reduction and improved glucose metabolism after sleeve gastrectomy and Roux-en-Y gastric bypass. However, few studies have examined the metabolic and endocrine effects of these procedures in Mainland China.

OBJECTIVES

To compare the effects of laparoscopic sleeve gastrectomy (LSG) and laparoscopic Roux-en-Y gastric bypass (LRYGB) on gastrointestinal and pancreatic peptide hormones.

SETTING

University hospital, China.

METHODS

A nonrandomized prospective study was conducted in Chinese obese patients undergoing LSG or LRYGB. Of 20 patients in this study, 10 underwent LSG, and 10 underwent LRYGB. Fasting plasma levels of insulin, glucagon, ghrelin, gastric inhibitory peptide, peptide YY, glucagon-like peptide (GLP)-1, and GLP-2 were measured preoperatively and at 1, 3, 6, and 12 months after surgery. This trial was registered at www.clinicaltrials.gov (NCT02963662).

RESULTS

During the first year after both operations, mean body mass index and fasting insulin levels steadily decreased at all intervals. Fasting plasma glucose levels significantly decreased at 1 month after surgery, then remained stable in both groups. Glucagon levels significantly decreased at 1, 3, and 6 months after surgery in both groups, but returned to baseline at 12 months. Fasting GLP-1 and peptide YY significantly increased in both groups, but more so after LRYGB. However, GLP-2 did not change in either group. Ghrelin levels significantly decreased after LSG, but not after LRYGB. Gastric inhibitory peptide levels decreased after LRYGB but not after LSG.

CONCLUSIONS

LSG and LRYGB resulted in significant and distinct changes in multiple gastrointestinal and pancreatic peptide hormones that are important regulators of obesity and metabolic health.

Restoration of enteroendocrine and pancreatic function after internal hernia and short bowel syndrome in a young woman with gastric bypass - a 2-year follow-up

A serious complication to the laparoscopic Roux‐en‐Y gastric bypass (RYGB) is internal hernia, which can lead to massive bowel necrosis that may result in short bowel syndrome. We determined postprandial enteropancreatic hormonal responses and metabolites in a 22‐year‐old nondiabetic woman with a history of RYGB experiencing severe internal herniation with widespread bowel necrosis. Extensive resections were performed leaving her with a saliva fistula from the pouch‐enteric anastomosis, an intact duodenum, 15 cm of jejunum, 35 cm of ileum, and intact colon. Parenteral nutrition was initiated and 10 months after the bowel resection, intestinal continuity was re‐established. After 6 weeks the patient reached parenteral nutrition independence. She underwent standardized liquid mixed meal tests before, 3 months after and 2 years after intestinal continuity was re‐established. Gut hormone responses were completely restored postoperatively leading to very high concentrations in plasma. After 2 years, plasma concentrations had, however, decreased markedly, suggesting desensitization of the gut ostensibly in response to chronic hyperstimulation. There was no evidence of cephalic phase insulin secretion.

Gastrectomy with Roux-en-Y reconstruction as a lean model of bariatric surgery

BACKGROUND

Altered enteroendocrine hormone responses are widely believed to underlie the beneficial effects of bariatric surgery in type 2 diabetes. While elevated postprandial glucagon-like peptide-1 (GLP-1) is considered one of the mediators, increased postprandial glucagon levels have recently been implicated.

OBJECTIVES

We investigated hormonal responses in lean patients after prophylactic total gastrectomy (PTG), as a model of Roux-en-Y gastric bypass without the confounding effects of obesity or massive weight loss.

SETTING

University hospital, United Kingdom.

METHODS

Ten participants after PTG and 9 healthy volunteers were recruited for oral glucose tolerance tests. Plasma glucose, insulin, GLP-1, peptide YY, glucose-dependent insulinotropic-polypeptide, glucagon, oxyntomodulin, glucagon(1-61), and glicentin levels were assessed using immunoassays and/or mass spectrometry.

RESULTS

PTG participants exhibited accelerated plasma glucose appearance, followed, in 3 of 10 cases, by hypoglycemia (<3 mM glucose). Plasma GLP-1, peptide YY, glucose-dependent insulinotropic-polypeptide, glicentin, and oxyntomodulin responses were elevated, and glucagon appeared to rise in PTG participants when measured with a glucagon-specific enzyme-linked immunosorbent assay. We revisited the specificity of this assay, and demonstrated significant cross-reactivity with glicentin and oxyntomodulin at concentrations observed in PTG plasma. Reassessment of glucagon with the same assay using a modified protocol, and by liquid chromatography-mass spectrometry, demonstrated suppression of glucagon secretion after oral glucose tolerance tests in both PTG and control cohorts.

CONCLUSIONS

Care should be taken when assessing glucagon levels in the presence of elevated plasma levels of other proglucagon products. Substantial elevation of GLP-1 and insulin responses after PTG likely contribute to the observed hypoglycemia, and mirror similar hormone levels and complications observed in bariatric weight loss patients.

Effect of the Duodenal-Jejunal Bypass Liner on Glycemic Control in Patients With Type 2 Diabetes With Obesity: A Meta-analysis With Secondary Analysis on Weight Loss and Hormonal Changes

OBJECTIVE

Duodenal-jejunal bypass liner (DJBL) is an endoscopic device that may mimic small bowel mechanisms of Roux-en-Y gastric bypass (RYGB). Previous studies have demonstrated the efficacy of DJBL at inducing weight loss. We assessed the effect of DJBL on glycemic control in patients with type 2 diabetes (T2D) with obesity.

RESEARCH DESIGN AND METHODS

Data sources included MEDLINE, EMBASE, and Web of Science through 1 July 2017. Included were published studies that assessed DJBL outcomes in obese T2D patients.

RESULTS

Primary outcomes were change in HbA_1c and HOMA of insulin resistance (HOMA-IR). Secondary outcomes were change in weight and gut hormones glucose-dependent insulinotropic peptide (GIP), glucagon-like peptide 1 (GLP-1), peptide YY (PYY), and ghrelin. Seventeen studies were included. At explant, HbA_1c decreased by 1.3% [95% CI 1.0, 1.6] and HOMA-IR decreased by 4.6 [2.9, 6.3]. Compared with control subjects, DJBL subjects had greater HbA_1c reduction by 0.9% [0.5, 1.3]. Six months after explant, HbA_1c remained lower than baseline by 0.9% [0.6, 1.2]. At explant, patients lost 11.3 kg [10.3, 12.2], corresponding to a BMI reduction of 4.1 kg/m² [3.4, 4.9], total weight loss of 18.9% [7.2, 30.6], and excess weight loss of 36.9% [29.2, 44.6]. The amount of weight loss remained significant at 1 year postexplantation. After DJBL, GIP decreased, whereas GLP-1, PYY, and ghrelin increased.

CONCLUSIONS

DJBL improves glycemic control and insulin resistance in T2D patients with obesity. DJBL also appears to induce significant weight loss in this population. Additionally, changes in gut hormones suggest mechanisms similar to RYGB. Study limitations included heterogeneity among studies.

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.

Bile acids are important direct and indirect regulators of the secretion of appetite- and metabolism-regulating hormones from the gut and pancreas

Objective

Bile acids (BAs) facilitate fat absorption and may play a role in glucose and metabolism regulation, stimulating the secretion of gut hormones. The relative importance and mechanisms involved in BA-stimulated secretion of appetite and metabolism regulating hormones from the gut and pancreas is not well described and was the purpose of this study.

Methods

The effects of bile acids on the secretion of gut and pancreatic hormones was studied in rats and compared to the most well described nutritional secretagogue: glucose. The molecular mechanisms that underlie the secretion was studied by isolated perfused rat and mouse small intestine and pancreas preparations and supported by immunohistochemistry, expression analysis, and pharmacological studies.

Results

Bile acids robustly stimulate secretion of not only the incretin hormones, glucose-dependent insulinotropic peptide (GIP), and glucagon-like peptide-1 (GLP-1), but also glucagon and insulin in vivo, to levels comparable to those resulting from glucose stimulation. The mechanisms of GLP-1, neurotensin, and peptide YY (PYY) secretion was secondary to intestinal absorption and depended on activation of basolateral membrane Takeda G-protein receptor 5 (TGR5) receptors on the L-cells in the following order of potency: Lithocholic acid (LCA) >Deoxycholicacid (DCA)>Chenodeoxycholicacid (CDCA)> Cholic acid (CA). Thus BAs did not stimulate secretion of GLP-1 and PYY from perfused small intestine in TGR5 KO mice but stimulated robust responses in wild type littermates. TGR5 is not expressed on α-cells or β-cells, and BAs had no direct effects on glucagon or insulin secretion from the perfused pancreas.

Conclusion

BAs should be considered not only as fat emulsifiers but also as important regulators of appetite- and metabolism-regulating hormones by activation of basolateral intestinal TGR5.

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Bile acids stimulate the secretion of metabolism-regulating hormones from the gut.

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Bile acids stimulate secretion of gut hormones to a similar extent as glucose.

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Activation of basolateral TGR5 receptors mediates the responses.

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Bile acids stimulate glucagon and insulin secretion, but only indirectly.

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Bile acids should be regarded as important regulators of blood glucose and metabolism.

Novel GLP-1/GLP-2 co-agonists display marked effects on gut volume and improves glycemic control in mice

AIM

Analogues of several gastrointestinal peptide hormones have been developed into effective medicines for treatment of diseases such as type 2 diabetes mellitus (T2DM), obesity and short bowel syndrome (SBS). In this study, we aimed to explore whether the combination of glucagon-like peptide-1 (GLP-1) and glucagon-like peptide-2 (GLP-2) into a potent co-agonist could provide additional benefits compared to existing monotherapies.

METHODS

A short-acting (GUB09-123) and a half-life extended (GUB09-145) GLP-1/GLP-2 co-agonist were generated using solid-phase peptide synthesis and tested for effects on food intake, body weight, glucose homeostasis, and gut proliferation in lean mice and in diabetic db/db mice.

RESULTS

Sub-chronic administration of GUB09-123 to lean mice significantly reduced food intake, improved glucose tolerance, and increased gut volume, superior to monotherapy with the GLP-2 analogue teduglutide. Chronic administration of GUB09-123 to diabetic mice significantly improved glycemic control and showed persistent effects on gastric emptying, superior to monotherapy with the GLP-1 analogue liraglutide. Due to the short-acting nature of the molecule, no effects on body weight were observed, whereas a marked and robust intestinotrophic effect on mainly the small intestine volume and surface area was obtained. In contrast to GUB09-123, sub-chronic administration of a half-life extended GUB09-145 to lean mice caused marked dose-dependent effects on body weight while maintaining its potent intestinotrophic effect.

CONCLUSION

Our data demonstrate that the GLP-1/GLP-2 co-agonists have effects on gut morphometry, showing a marked increase in intestinal volume and mucosal surface area. Furthermore, effects on glucose tolerance and long-term glycemic control are evident. Effects on body weight and gastric emptying are also observed depending on the pharmacokinetic properties of the molecule. We suggest that this novel co-agonistic approach could exemplify a novel concept for treatment of T2DM or SBS.

Omeprazole Absorption and Fasting Gastrinemia After Roux-en-Y Gastric Bypass

PURPOSE

Roux-en-Y gastric bypass (RYGB) is one of the bariatric surgeries most frequently performed worldwide. Since this operation may predispose to the formation of peptic ulcer of the gastrojejunal anastomosis, the use of proton pump inhibitors (PPI) is recommended during the first postoperative year. However, so far, there is no detailed knowledge about the absorption of this medication during the immediate postoperative period and consequently about its effectiveness in blocking acid secretion. The objective was to assess the possible endoscopic peptic changes, the absorption of omeprazole (OME), and the status of fasting gastrinemia before and after RYGB operation.

MATERIALS AND METHODS

OME absorption, the production of its metabolites omeprazole sulfone (OMES) and 5-hydroxyomeprazole (HOME), and basal (fasting) gastrinemia were determined in patients submitted to RYGB before and 2 months after the operation. Upper digestive endoscopy (UDE) was also performed before and 6 months after the operation.

RESULTS

Twenty patients were studied. Preoperatively, all these patients had some peptic changes and 55% tested positive for Helicobacter pylori. Six months after surgery, ten patients still showed endoscopic changes and one patient tested positive for H. pylori. During the postoperative period, there was a reduction of OME absorption and of the production of its metabolites 90 min after administration of the drug, and reduction of serum gastrin levels.

CONCLUSION

The standard OME dose (40 mg) administered after bariatric surgery is insufficient to achieve serum levels that can effectively block the production of hydrochloric acid, permitting the formation of peptic injuries in many patients.

Mechanisms in bariatric surgery: Gut hormones, diabetes resolution, and weight loss

Gastric bypass surgery leads to profound changes in the secretion of gut hormones with effects on metabolism, appetite, and food intake. Here, we discuss their contributions to the improvement in glucose tolerance and the weight loss that results from the operations. We find that the improved glucose tolerance is due the following events: a negative energy balance and resulting weight loss, which improve first hepatic and later peripheral insulin sensitivity, in combination with increased postprandial insulin secretion elicited particularly by exaggerated glucagon-like peptide-1 responses. The weight loss is due to loss of appetite resulting in reduced energy intake, and we find it probable that this process is driven by exaggerated secretion of appetite-regulating gut hormones including, but probably not limited to, glucagon-like peptide-1 and peptide-YY. The increased secretion is due to an accelerated exposure to and absorption of nutrients in the small intestine. This places the weight loss and the gut hormones in key positions with respect to the metabolic improvements after bypass surgery.

Male grower pigs fed cereal soluble dietary fibres display biphasic glucose response and delayed glycaemic response after an oral glucose tolerance test

Acute and sustained soluble dietary fibre (SDF) consumption are both associated with improved glucose tolerance in humans and animal models (e.g. porcine). However, the effects on glucose tolerance in grower pigs, adapted to diets with a combination of SDF have not been studied previously. In this experiment, cereal SDF wheat arabinoxylan (AX) and oat β-glucan (BG) were fed individually and in combination to determine the effect on glucose tolerance in jugular vein catheterized grower pigs. Five groups of Large White male grower pigs were fed highly digestible diets containing either 10% AX, 10% BG, 5% AX with 5% BG, a model cereal whole wheat flour (WWF), or a control wheat starch diet (WS) with no SDF. Blood was collected via jugular vein catheters over 240 minutes following a feed challenge and an oral glucose tolerance test (OGTT) on two separate days. Postprandial blood samples were used to determine plasma glucose, insulin, non-esterified fatty acids (NEFA), glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide-1 (GLP-1), peptide tyrosine tyrosine (PYY), ghrelin, glucagon and cortisol concentrations. No dietary effects on glycaemic response were observed following the feed challenge or the OGTT as determined by the area under the curve (AUC). A biphasic glucose and insulin response was detected for all pigs following the OGTT. The current study showed male grower pigs have tight glycaemic control and glucose tolerance regardless of diet. In addition, pigs fed the combined SDF had a reduced GIP response and delayed insulin peak following the feed challenge. Incretin (GLP-1 and GIP) secretion appeared asynchronous reflecting their different enteroendocrine cell locations and response to nutrient absorption.

Bone Health following Bariatric Surgery: Implications for Management Strategies to Attenuate Bone Loss

Bariatric surgery (BS) is an effective treatment for morbid obesity and its associated comorbidities. Following such a procedure, however, patients are at risk of developing metabolic bone disease owing to the combination of rapid weight loss, severely restricted dietary intake, and reduced intestinal nutrient absorption. Patients undergoing malabsorptive procedures are at a higher risk of postoperative bone health deterioration than those undergoing restrictive procedures; however, studies have demonstrated negative skeletal consequences of restrictive procedures as well. The clinical practice guidelines of some international associations have previously addressed preoperative evaluation and postoperative clinical care in order to maintain bone health in BS patients. Nevertheless, some issues regarding bone health in BS patients remain unclear owing to the lack of relevant randomized clinical trials, including doses of nutritional supplements pre- and post-BS. This review summarizes the current data regarding the skeletal consequences of BS and its mechanisms, with an emphasis on the preventive strategies and nutritional care that may be warranted in order to attenuate bone deterioration following BS.

Glucagon like peptide-2 and neoplasia; a systematic review

Glucagon like peptide-2 is synthesized from enteroendocrine L cells primarily located in the ileum and large intestine. GLP-2 stimulates crypt cell proliferation, increases intestinal blood flow, enhances gut barrier function, induces mucosal healing, and exerts an anti-apoptotic effect. Due to these effects GLP-2 is used in the treatment of short bowel syndrome (SBS). Areas covered: The aim of this systematic review was to provide information on the potential risk of intestinal neoplasia in patients receiving treatment with GLP-2. The literature search was performed independently by two authors in the following databases; Pubmed, Embase, Scopus, Web of Science and Cochrane. Expert commentary: This systematic review indicated that treatment with GLP-2(1-33) up to 30 months in humans without any known pre-existing cancer did not confer an increased risk of intestinal neoplasia in patients or animals. However, due to the small amount of patients studied it is premature to reach any final conclusions about GLP-2 - induced neoplasia. GLP-2(1-33) treatment in animals with a pre-induced cancer showed that GLP-2(1-33) may promote growth of existing neoplasia.

Mechanisms to Elevate Endogenous GLP-1 Beyond Injectable GLP-1 Analogs and Metabolic Surgery

Therapeutic engineering of glucagon-like peptide 1 (GLP-1) has enabled development of new medicines to treat type 2 diabetes. These injectable analogs achieve robust glycemic control by increasing concentrations of "GLP-1 equivalents" (∼50 pmol/L). Similar levels of endogenous GLP-1 occur after gastric bypass surgery, and mechanistic studies indicate glucose lowering by these procedures is driven by GLP-1. Therefore, because of the remarkable signaling and secretory capacity of the GLP-1 system, we sought to discover mechanisms that increase GLP-1 pharmacologically. To study active GLP-1, glucose-dependent insulinotropic polypeptide receptor (Gipr)-deficient mice receiving background dipeptidyl peptidase 4 (DPP4) inhibitor treatment were characterized as a model for evaluating oral agents that increase circulating GLP-1. A somatostatin receptor 5 antagonist, which blunts inhibition of GLP-1 release, and agonists for TGR5 and GPR40, which stimulate GLP-1 secretion, were investigated alone and in combination with the DPP4 inhibitor sitagliptin; these only modestly increased GLP-1 (∼5-30 pmol/L). However, combining molecules to simultaneously intervene at multiple regulatory nodes synergistically elevated active GLP-1 to unprecedented concentrations (∼300-400 pmol/L), drastically reducing glucose in Gipr null and Lepr^db/db mice in a GLP-1 receptor-dependent manner. Our studies demonstrate that complementary pathways can be engaged to robustly increase GLP-1 without invasive surgical or injection regimens.

Intestinal peptide changes after bariatric and minimally invasive surgery: Relation to diabetes remission

Bariatric surgery is very effective in achieving and maintaining weight loss but it is also associated with improvement of obesity metabolic complications, primarily type 2 diabetes (T2D). Remission of T2D or at least a net improvement of glycemic control persists for at least 5 years. The bypass of duodenum and of the first portion of the jejunum up to the Treitz ligament as in Roux-en-Y Gastric Bypass (RYGB), or the bypass of the duodenum, the entire jejunum and the first tract of the ileum, such as in Bilio-Pancreatic Diversion (BPD), achieve different results on insulin sensitivity. Insulin resistance is the major driver of T2D manifesting long before insulin secretion failure. In fact, T2D development can be prevented by treatment with insulin sensitizing agents. Interestingly, RYGB improves hepatic insulin sensitivity while BPD ameliorates whole-body insulin sensitivity. Two major theories have been advocated to explain the early remission of T2D following RYGB or BPD before a meaningful weight loss takes place, the foregut and the hindgut hypotheses. The former holds that the bypass of the proximal intestine, i.e. duodenum and jejunum, prevents the secretion of signals - including nervous transmitters and hormones - promoting insulin resistance, the latter instead states that the delivery of nutrients directly into the ileum stimulates the secretion of hormones improving glucose disposal. The most studied candidate is Glucagon Like Peptide 1 (GLP1). However, while there is unambiguous evidence that GLP-1 stimulates insulin secretion, its direct action in lowering insulin resistance, independently of the effect on weight loss secondary to its satiety action, is utterly controversial. In this review we examine the effects on T2D and gastrointestinal peptide secretion produced by different types of metabolic surgery and by minimally invasive endoscopic surgery, whose utilization for the treatment of obesity and T2D is gaining wider interest and acceptance.

Regulation of Energy Homeostasis After Gastric Bypass Surgery

The obesity epidemic continues to escalate each year in the United States more than anywhere else in the world. The existing pharmaceutical and other nonsurgical treatments for morbid obesity produce suboptimal physiologic outcomes compared with those of Roux-en-Y gastric bypass (RYGB) surgery. RYGB has been the gold standard of bariatric surgery because the beneficial long-term outcomes, which include sustainable weight loss and type 2 diabetes mellitus (T2DM) resolution, are far superior to those obtained with other bariatric surgeries. However, the current understanding of RYGB's mechanisms of actions remains limited and incomplete. There is an urgent need to understand these mechanisms as gaining this knowledge may lead to the development of innovative and less invasive procedures and/or medical devices, which can mirror the favorable outcomes of RYGB surgery. In this review, we highlight current observations of the metabolic and physiologic events following RYGB, with a particular focus on the role of the anatomical reconfiguration of the gastrointestinal tract after RYGB.

The Role of GLP-1 in the Metabolic Success of Bariatric Surgery

Two of the most popular bariatric procedures, vertical sleeve gastrectomy (VSG) and Roux-en-Y gastric bypass (RYGB), are commonly considered metabolic surgeries because they are thought to affect metabolism in a weight loss-independent manner. In support of this classification, improvements in glucose homeostasis, insulin sensitivity, and even discontinuation of type 2 diabetes mellitus (T2DM) medication can occur before substantial postoperative weight loss. The mechanisms that underlie this effect are unknown. However, one of the common findings after VSG and RYGB in both animal models and humans is the sharp postprandial rise in several gut peptides, including the incretin and satiety peptide glucagonlike peptide-1 (GLP-1). The increase in endogenous GLP-1 signaling has been considered a primary pathway leading to postsurgical weight loss and improvements in glucose metabolism. However, the degree to which GLP-1 and other gut peptides are responsible for the metabolic successes after bariatric surgery is continually debated. In this review we discuss the mechanisms underlying the increase in GLP-1 and its potential role in the metabolic improvements after bariatric surgery, including remission of T2DM. Understanding the role of changes in gut peptides, or lack thereof, will be crucial in understanding the critical factors necessary for the metabolic success of bariatric surgery.

Serum Leptin and Adiponectin Concentration in Type 2 Diabetes Patients in the Short and Long Term Following Biliopancreatic Diversion

BACKGROUND

A deranged adipokine system is implicated in obesity and in type 2 diabetes mellitus (T2DM), and the lack of remission of T2DM after bariatric surgery could be also accounted for by the postoperative persistence of this condition.

METHODS

Thirty T2DM patients undergoing biliopancreatic diversion (BPD) with a wide range of baseline body mass index (BMI) were evaluated prior to and at 1 and 5 years following BPD. Besides the usual clinical evaluations, acute insulin response (AIR) to intravenous glucose load as a parameter of insulin secretion and the serum leptin and adiponectin concentration were measured throughout the follow-up period in all patients.

RESULTS

A long-term T2DM remission was observed in 21 patients (70 %). Serum leptin level reduced at the first year and remained substantially unchanged at a long term in both the remitter and non-remitter patients, while following the operation, a progressive significant increase of serum adiponectin level was observed only in remitter patients (from 9.2 to 12.3 μg/mL at 1 year and to 15.18 μg/mL at 5 years in the remitters and from 8.8 to 8.75 μg/mL at 1 year and to 11.8 μg/mL at 5 years in the non-remitters). Serum leptin mean values were positively associated with the BMI ones both prior to and following BPD (p < 0.005), while serum adiponectin values were positively related (p < 0.04) to the postoperative AIR data.

CONCLUSIONS

The improvement of the pattern of cytokine production, as evidenced by postoperative rise in serum adiponectin concentration, might play a role in T2DM remission after bariatric surgery.

Acute effects of glucagon-like peptide-1, GLP-19-36 amide, and exenatide on mesenteric blood flow, cardiovascular parameters, and biomarkers in healthy volunteers

Glucagon‐like peptide‐1 (GLP‐1, GLP‐1_7–36amide) and its sister peptide glucagon‐like peptide 2 (GLP‐2) influence numerous intestinal functions and GLP‐2 greatly increases intestinal blood flow. We hypothesized that GLP‐1 also stimulates intestinal blood flow and that this would impact on the overall digestive and cardiovascular effects of the hormone. To investigate the influence of GLP‐1 receptor agonism on mesenteric and renal blood flow and cardiovascular parameters, we carried out a double‐blinded randomized clinical trial. A total of eight healthy volunteers received high physiological subcutaneous injections of GLP‐1, GLP‐1_{9–36 amide} (bioactive metabolite), exenatide (stable GLP‐1 agonist), or saline on four separate days. Blood flow in mesenteric, celiac, and renal arteries was measured by Doppler ultrasound. Blood pressure, heart rate, cardiac output, and stroke volume were measured continuously using an integrated system. Plasma was analyzed for glucose, GLP‐1 (intact and total), exenatide and Pancreatic polypeptide (PP), and serum for insulin and C‐peptide. Neither GLP‐1, GLP‐1_{9–36 amide}, exenatide nor saline elicited any changes in blood flow parameters in the mesenteric or renal arteries. GLP‐1 significantly increased heart rate (two‐way ANOVA, injection [P = 0.0162], time [P = 0.0038], and injection × time [P = 0.082]; Tukey post hoc GLP‐1 vs. saline and GLP‐1_9–36amide [P < 0.011]), and tended to increase cardiac output and decrease stroke volume compared to GLP‐1_{9–36 amide} and saline. Blood pressures were not affected. As expected, glucose levels fell and insulin secretion increased after infusion of both GLP‐1 and exenatide.

Hyperinsulinemic hypoglycemia after gastric bypass surgery: what's up and what's down?

Obesity is a global public health problem and attempts to treat this condition using life style with and without pharmacological interventions have not been successful in majority of obese individuals. To date, the most effective treatment for obesity is weight loss surgery. One of the most widely used procedures to treat obesity worldwide, Roux-en-Y gastric bypass surgery (RYGB), has shown to induce diabetes remission in addition to significant and sustainable weight loss. As the number of this procedure performed over the last two decades increased, it has become clear that a subgroup of individuals develop postprandial hypoglycemia several years after surgery. This debilitating late complication of RYGB is often associated with loss of consciousness or seizures, and in severe cases, it is only partially responsive to diet modification or other available therapeutic options. The diagnosis is often a challenge resulting in delays in receiving care in the affected individuals. Although the underlying mechanisms are under current investigations, growing evidence suggest that a combination of exaggerated meal-derived nutrient appearance to systemic circulation and altered islet and gut hormone response after eating have a role in pathogenesis of this condition. The goal of this review is to highlight new perspectives regarding this life-threatening complication of RYGB. The etiology, diagnosis, recommendation on how to distinguish from classic dumping and current available treatment based on literature review will be discussed. In addition, physiologic changes after gastric bypass predisposing to hypoglycemia syndrome will be highlighted.International Journal of Obesity advance online publication, 31 October 2017; doi:10.1038/ijo.2017.257.

Neuroendocrine mechanisms underlying bariatric surgery: Insights from human studies and animal models

Obesity has reached epidemic proportions and, to date, bariatric surgery remains the only effective treatment for morbid obesity in terms of its capacity to achieve durable weight loss. Bariatric surgery procedures, including Roux-en-Y gastric bypass (RYGB), adjustable gastric banding (AGB) and sleeve gastrectomy (SG), have been the primary procedures conducted over the past decade, with SG increasing in popularity over the past 5 years at the expense of both RYGB and AGB. Although these procedures were initially proposed to function via restrictive or malabsorptive mechanisms, it is now clear that profound physiological changes underlie the metabolic improvements in patients who undergo bariatric surgery. Data generated in human patients and animal models highlight the rapid and sustained changes in gut hormones that coincide with these procedures. Furthermore, recent studies highlight the involvement of the nervous system, specifically the vagus nerve, in mediating the reduction in appetite and food intake following bariatric surgery. What is unclear is where these pathways converge and interact within the gut-brain axis and whether vagally-mediated circuits are sufficient to drive the metabolic sequalae following bariatric surgery.

Solo Single-Incision Laparoscopic Resectional Roux-en-Y Gastric Bypass for Morbid Obesity with Metabolic Syndrome

With the advancement of laparoscopic devices and surgical technology, the era of minimal invasive surgery has progressed to reduced-port surgery, and finally to single-incision laparoscopic surgery (SILS). Several reports show successful application of SILS to various types of bariatric surgery. Oftentimes, this requires a skilled and experienced scopist to perform the procedure. To overcome the technical difficulties of single-incision Roux-en-Y gastric bypass, a manual scope holder was used instead of an assistant scopist, greatly stabilizing the field of view. This allows the surgery to be performed at any time without being influenced by the need of a highly experienced scopist. In this report, we describe in detail the world's first solo single-incision laparoscopic resectional Roux-en-Y gastric bypass.

Neuroendocrine regulation of energy balance: Implications on the development and surgical treatment of obesity

INTRODUCTION

Obesity, a serious public health problem, occurs mainly when food consumption exceeds energy expenditure. Therefore, energy balance depends on the regulation of the hunger-satiety mechanism, which involves interconnection of the central nervous system and peripheral signals from the adipose tissue, pancreas and gastrointestinal tract, generating responses in short-term food intake and long-term energy balance. Increased body fat alters the gut- and adipose-tissue-derived hormone signaling, which promotes modifications in appetite-regulating hormones, decreasing satiety and increasing hunger senses. With the failure of conventional weight loss interventions (dietary treatment, exercise, drugs and lifestyle modifications), bariatric surgeries are well-accepted tools for the treatment of severe obesity, with long-term and sustained weight loss. Bariatric surgeries may cause weight loss due to restriction/malabsorption of nutrients from the anatomical alteration of the gastrointestinal tract that decreases energy intake, but also by other physiological factors associated with better results of the surgical procedure.

OBJECTIVE

This review discusses the neuroendocrine regulation of energy balance, with description of the predominant hormones and peptides involved in the control of energy balance in obesity and all currently available bariatric surgeries.

CONCLUSIONS

According to the findings of our review, bariatric surgeries promote effective and sustained weight loss not only by reducing calorie intake, but also by precipitating changes in appetite control, satiation and satiety, and physiological changes in gut-, neuro- and adipose-tissue-derived hormone signaling.

Differential expression of glucagon-like peptide-2 (GLP-2) is involved in pancreatic islet cell adaptations to stress and beta-cell survival

Recent studies have confirmed that locally released proglucagon derived gene products, other than glucagon, have a major influence on pancreatic endocrine function. We assessed the impact of glucagon-like peptide-2 (GLP-2) on beta-cell secretory function, proliferation and apoptosis, as well as glucose tolerance, feeding behaviour and islet adaptions to chemically-induced insulin deficiency and resistance. The GLP-2 receptor was evidenced on cultured rodent and human beta-cells, rodent alpha-cells and isolated mouse islets. GLP-2 had no effect on insulin secretion from beta-cells, or isolated mouse islets. In vivo, GLP-2 administration significantly (P<0.05 to P<0.01) decreased food intake in mice. Conversely, GLP-2 had no discernible effects on glucose disposal or insulin secretion. As expected, streptozotocin treatment decreased and hydrocortisone increased beta-cell mass in mice. GLP-2 was visualised in mouse islets and intestinal L-cells. Islet GLP-2 co-localisation with glucagon was significantly decreased (P<0.01) by both streptozotocin and hydrocortisone. In contrast, both interventions increased (P<0.05) co-localisation of GLP-2 with somatostatin. Interestingly, GLP-2 positive cells were reduced (P<0.05) in the intestines of streptozotocin, but not hydrocortisone, treated mice. Further in vitro investigations revealed that GLP-2 protected rodent and human 1.1B4 beta-cells against streptozotocin induced DNA damage. Furthermore, GLP-2 augmented (P<0.05) BRIN BD11 beta-cell proliferation, but was less efficacious in 1.1B4 cells. These data highlight the involvement of GLP-2 receptor signalling in the adaptations to pancreatic islet cell stress.

Biliopancreatic diversion with duodenal switch leads to better postprandial glucose level and beta cell function than sleeve gastrectomy in individuals with type 2 diabetes very early after surgery

OBJECTIVE

The aim of this study was to compare the short-term effect of sleeve gastrectomy (SG) and biliopancreatic diversion with duodenal switch (DS) in order to determine if exclusion of the upper gastrointestinal tract confers greater metabolic improvement, independent of weight loss.

METHODS

Standard meals were administered before and on day 3 and 4 after SG to assess insulin sensitivity, β-cell function and gastrointestinal hormone responses in matched normoglycemic (NG) and type 2 diabetes (T2D) participants. A third group of matched T2D participants who underwent DS with the same meal test administered prior to and 3days after surgery was also recruited.

RESULTS

Despite significant metabolic improvement, T2D participants failed to fully normalize insulin resistance and β-cell dysfunction 3 and 4days after SG. Our results demonstrate the superiority of DS over SG in terms of short-term improvement in postprandial glucose excursion and β-cell function 3days after the surgery, with similar improvement in hepatic insulin sensitivity.

CONCLUSION

Our findings support the notion that caloric restriction represents an important mechanism to explain the very early anti-diabetic effects observed after bariatric surgery. However, exclusion of the upper gastrointestinal tract also provides further metabolic improvements, possibly mediated by gastrointestinal hormonal responses and altered postprandial glucose absorption.

Potential Hormone Mechanisms of Bariatric Surgery

PURPOSE OF REVIEW

In recent years, the role of the gastrointestinal (GI) tract in energy homeostasis through modulation of the digestion and absorption of carbohydrates and the production of incretin hormones is well recognized.

RECENT FINDINGS

Bariatric surgery for obesity has been a very effective method in substantially improving weight, and numerous studies have focused on intestinal adaptation after bariatric procedures. A number of structural and functional changes in the GI tract have been reported postsurgery, which could be responsible for the altered hormonal responses. Furthermore, the change in food absorption rate and the intestinal regions exposed to carbohydrates may affect blood glucose response. This review hopes to give new insights into the direct role of gut hormones, by summarising the metabolic effects of bariatric surgery.

Comprehensive Care for Bariatric Surgery Patients

Obesity is a worldwide epidemic, and those suffering from obesity have increased morbidity and mortality rates. There are various causes of obesity and many treatment options for patients suffering from obesity, including nonsurgical treatments. However, bariatric surgery is often the best choice for optimal weight loss and the attenuation of comorbidities. Currently, laparoscopic sleeve gastrectomy is the most common type of bariatric surgery in the United States due to its technical simplicity, feasibility, and overall positive outcomes. This article discusses bariatric surgical criteria and selection, expected perioperative course, potential complications after surgery, and nursing implications for the care of bariatric patients. A case report is used to exemplify stages of surgical care and follow-up treatment for patients who undergo laparoscopic sleeve gastrectomy.

Pancreatic islet regeneration through PDX-1/Notch-1/Ngn3 signaling after gastric bypass surgery in db/db mice

In view of the compelling anti-diabetic effects of gastric bypass surgery (GBS) in the treatment of morbid obesity, it is important to clarify its enhancing effect on pancreatic islets, which is closely linked with diabetes remission in obese patients, as well as the underlying mechanisms. The present study evaluated the effects of GBS on glycemic control and other pancreatic changes in db/db mice. The db/db mice were divided into Control, Sham and GBS group. A significant improvement in fasting plasma glucose levels and glucose intolerance were observed post-surgery. At 4 weeks after surgery, further noteworthy changes were observed in the GBS group, including improved islet structure (revealed by immunohistochemical analysis), enhanced insulin secretion, pancreatic hyperplasia and a marked increase in the ratio of β-cells to non-β endocrine cells. Furthermore, notable changes in the levels of Notch-1, pancreatic and duodenal homeobox 1 (PDX-1) and neurogenin 3 (Ngn3) were observed in the GBS group, indicating a potential role of Notch signaling in pancreatic islet regeneration after surgery. In addition, results obtained in PDX-1 knockout (KO), Notch-1 KO and Ngn3 KO mouse models with GBS suggested that elevated PDX-1 resulted in the inhibition of Notch-1, further facilitated Ngn3 and thus promoted pancreatic β-cell regeneration after GBS. The present findings demonstrated that GBS in db/db mice resulted in pancreatic islet regeneration through the PDX-1/Notch-1/Ngn3 signaling pathway, which also reflected the important role of the gastrointestinal system in metabolism control.

Pancreatic and Intestinal Function Post Roux-en-Y Gastric Bypass Surgery for Obesity

OBJECTIVES

Despite the fact that the most effective treatment for morbid obesity today is gastric bypass surgery, some patients develop life-threatening nutritional complications associated with their weight loss.

METHODS

Here we examine the influence of the altered anatomy and digestive physiology on pancreatic secretion and fat absorption. Thirteen post Roux-en-Y gastric bypass (RYGB) patients who had lost >100 lbs in the first year following surgery and who gave variable histories of gastrointestinal (GI) dysfunction, were selected for study. Food-stimulated pancreatic enzyme secretion and GI hormone responses were measured during 2 h perfusions of the Roux limb with a standard polymeric liquid formula diet and polyethylene glycol marker, with collections of secretions from the common channel distal to the anastomosis and blood testing. Fat absorption was then measured during a 72 h balance study when a normal diet was given containing ~100 g fat/d.

RESULTS

Result showed that all patients had some fat malabsorption, but eight had coefficients of fat absorption <80%, indicative of steatorrhea. This was associated with significantly lower feed-stimulated secretion rates of trypsin, amylase, and lipase, and higher plasma peptide-YY concentrations compared with healthy controls. Five steatorrhea patients were subsequently treated with low quantities of pancreatic enzyme supplements for 3 months, and then retested. The supplements were well tolerated, and fat absorption improved in four of five patients accompanied by an increase in lipase secretion, but body weight increased in only three. Postprandial breath hydrogen concentrations were elevated with some improvement following enzyme supplementation suggesting persistent bacterial overgrowth and decreased colonic fermentation.

CONCLUSIONS

Our investigations revealed a wide spectrum of gastrointestinal abnormalities, including fat malabsorption, impaired food stimulated pancreatic secretion, ileal brake stimulation, and bacterial overgrowth, in patients following RYGB which could be attributed to the breakdown of the normally highly orchestrated digestive anatomy and physiology.

Is There a Role for Bioactive Lipids in the Pathobiology of Diabetes Mellitus?

Inflammation, decreased levels of circulating endothelial nitric oxide (eNO) and brain-derived neurotrophic factor (BDNF), altered activity of hypothalamic neurotransmitters (including serotonin and vagal tone) and gut hormones, increased concentrations of free radicals, and imbalance in the levels of bioactive lipids and their pro- and anti-inflammatory metabolites have been suggested to play a role in diabetes mellitus (DM). Type 1 diabetes mellitus (type 1 DM) is due to autoimmune destruction of pancreatic β cells because of enhanced production of IL-6 and tumor necrosis factor-α (TNF-α) and other pro-inflammatory cytokines released by immunocytes infiltrating the pancreas in response to unknown exogenous and endogenous toxin(s). On the other hand, type 2 DM is due to increased peripheral insulin resistance secondary to enhanced production of IL-6 and TNF-α in response to high-fat and/or calorie-rich diet (rich in saturated and trans fats). Type 2 DM is also associated with significant alterations in the production and action of hypothalamic neurotransmitters, eNO, BDNF, free radicals, gut hormones, and vagus nerve activity. Thus, type 1 DM is because of excess production of pro-inflammatory cytokines close to β cells, whereas type 2 DM is due to excess of pro-inflammatory cytokines in the systemic circulation. Hence, methods designed to suppress excess production of pro-inflammatory cytokines may form a new approach to prevent both type 1 and type 2 DM. Roux-en-Y gastric bypass and similar surgeries ameliorate type 2 DM, partly by restoring to normal: gut hormones, hypothalamic neurotransmitters, eNO, vagal activity, gut microbiota, bioactive lipids, BDNF production in the gut and hypothalamus, concentrations of cytokines and free radicals that results in resetting glucose-stimulated insulin production by pancreatic β cells. Our recent studies suggested that bioactive lipids, such as arachidonic acid, eicosapentaneoic acid, and docosahexaenoic acid (which are unsaturated fatty acids) and their anti-inflammatory metabolites: lipoxin A4, resolvins, protectins, and maresins, may have antidiabetic actions. These bioactive lipids have anti-inflammatory actions, enhance eNO, BDNF production, restore hypothalamic dysfunction, enhance vagal tone, modulate production and action of ghrelin, leptin and adiponectin, and influence gut microbiota that may explain their antidiabetic action. These pieces of evidence suggest that methods designed to selectively deliver bioactive lipids to pancreatic β cells, gut, liver, and muscle may prevent type 1 and type 2 DM.

The Role of PYY in Pancreatic Islet Physiology and Surgical Control of Diabetes

Bariatric surgery in obese individuals leads to rapid and lasting remission of type 2 diabetes (T2D). This phenomenon occurs independently of weight loss possibly via a combination of factors. The incretin hormone GLP-1 has so far been recognised as a critical factor. However, recent data have indicated that elevation in another gut hormone, peptide tyrosine tyrosine (PYY), may drive the beneficial effects of surgery. Here we discuss recent findings on PYY-mediated control of glucose homeostasis and its role in diabetes, in the context of what is known for GLP-1. Identification of factors that increase the expression of PYY following bariatric surgery and elucidation of its role in diabetes reversal may have clinical relevance as a nonsurgical therapy for T2D.

Gut-Brain Cross-Talk in Metabolic Control

Because human energy metabolism evolved to favor adiposity over leanness, the availability of palatable, easily attainable, and calorically dense foods has led to unprecedented levels of obesity and its associated metabolic co-morbidities that appear resistant to traditional lifestyle interventions. However, recent progress identifying the molecular signaling pathways through which the brain and the gastrointestinal system communicate to govern energy homeostasis, combined with emerging insights on the molecular mechanisms underlying successful bariatric surgery, gives reason to be optimistic that novel precision medicines that mimic, enhance, and/or modulate gut-brain signaling can have unprecedented potential for stopping the obesity and type 2 diabetes pandemics.

Intestinal Adaptations after Bariatric Surgery: Consequences on Glucose Homeostasis

The gastrointestinal (GI) tract can play a direct role in glucose homeostasis by modulating the digestion and absorption of carbohydrates and by producing the incretin hormones. In recent years, numerous studies have focused on intestinal adaptation following bariatric surgeries. Changes in the number of incretin (glucagon-like peptide 1 and glucose-dependent insulinotropic polypeptide) producing cells have been reported, which could result in the modified hormonal response seen after surgery. In addition, the rate of absorption and the intestinal regions exposed to sugars may affect the time course of appearance of glucose in the blood. This review gives new insights into the direct role of the GI tract in the metabolic outcomes of bariatric surgery, in the context of glucose homeostasis.

Gastric bypass in the pig increases GIP levels and decreases active GLP-1 levels

Gastric bypass surgery results in remission of type 2 diabetes in the majority of patients. The incretin hormones glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) have been implicated in the observed remission. Most knowledge so far has been generated in obese subjects. To isolate the surgical effects of gastric bypass on metabolism and hormone responses from the confounding influence of obesity, T2D, or food intake, we performed gastric bypass in lean pigs, using sham-operated and pair-fed pigs as controls. Thus, pigs were subjected to Roux-en-Y gastric bypass (RYGB) or sham surgery and oral glucose tolerance tests (OGTT). RYGB pigs and sham pigs exhibited similar basal and 120-min glucose levels in response to the OGTT. However, RYGB pigs had approximately 1.6-fold higher 30-min glucose (p<0.01). Early insulin release (EIR) was enhanced approximately 3.5-fold in the RYGB pigs (p<0.01). Furthermore, GIP release, both acute and sustained release (p<0.001 and p<0.01, respectively), was increased approximately 2.5-fold and 1.4-fold, respectively, in RYGB pigs. Although total GLP-1 release increased approximately 2.1-fold after RYGB (p<0.001), active GLP-1 was 33% lower (p<0.01). Interestingly basal DPP4-activity was approximately 3.2-fold higher in RYGB pigs (p<0.001). In conclusion, RYGB in lean pigs increases the response of GIP, total GLP-1, and insulin, but reduces levels of active GLP-1 in response to an oral glucose load. These data challenge the role of active GLP-1 as a contributor to remission from diabetes after RYGB.

Hydrothermal Duodenal Mucosal Resurfacing: Role in the Treatment of Metabolic Disease

The duodenum has become recognized as a metabolic signaling center that is involved in regulating insulin action and, therefore, insulin resistance states such as type 2 diabetes. Bariatric surgery and other manipulations of the upper intestine, in particular the duodenum, have shown that limiting nutrient exposure or contact in this key region exerts powerful metabolic effects. Early human clinical trial data suggest that endoscopic hydrothermal duodenal mucosal resurfacing is well tolerated in human subjects and has an acceptable safety profile. This article describes the rationale for this endoscopic approach and its early human use, including safety, tolerability, and early efficacy.