Altered glucose metabolism after bariatric surgery: What's GLP-1 got to do with it?

Tirzepatide Improves Early Dumping Syndrome and Glucose Nadir in Postbariatric Hypoglycemia After Sleeve Gastrectomy

Early dumping syndrome (DS) and postbariatric hypoglycemia (PBH) are challenging conditions with limited treatment options. A 46-year-old woman with prediabetes, obesity, and sleeve gastrectomy presented with digestive symptoms suggestive of DS and postprandial hypoglycemia consistent with PBH. She started tirzepatide 2.5 mg weekly, which decreased postprandial blood glucose peaks, increased postprandial blood glucose nadirs, and improved overall time in range on continuous glucose monitoring (CGM). Her postprandial bloating and diarrhea resolved. To our knowledge, there have been no reported cases of DS or PBH treated with dual-incretin agonists. While glucagon-like peptide-1 (GLP-1) agonists have not been widely attempted in DS and have shown mixed benefit for PBH, combination GLP-1 and gastric inhibitory peptide agonism may represent a novel treatment both for PBH and DS, providing greater improvement in glycemic variation as well as better DS control than GLP-1 agonism alone.

Practical guide: Glucagon-like peptide-1 and dual glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1 receptor agonists in diabetes mellitus

In 2005, exenatide became the first approved glucagon-like peptide-1 receptor agonist (GLP-1 RA) for type 2 diabetes mellitus (T2DM). Since then, numerous GLP-1 RAs have been approved, including tirzepatide, a novel dual glucose-dependent insulinotropic polypeptide (GIP)/GLP-1 RA, which was approved in 2022. This class of drugs is considered safe with no hypoglycemia risk, making it a common second-line choice after metformin for treating T2DM. Various considerations can make selecting and switching between different GLP-1 RAs challenging. Our study aims to provide a comprehensive guide for the usage of GLP-1 RAs and dual GIP and GLP-1 RAs for the management of T2DM.

Comparison of three different anastomotic methods of sleeve gastrectomy with transit bipartition using an obese rodent model

The long-term effects and safety of single-anastomosis sleeve ileal (SASI) bypass have not been confirmed. The one anastomosis procedure carries the risk of bile reflux, and Braun anastomosis has the capacity to reduce bile reflux. This study was designed to compare the influences of bile reflux and histological changes in the esogastric sections of rats. Obese Sprague-Dawley rats underwent sleeve gastrectomy with transit bipartition (RYTB) (n = 12), SASI (n = 12), SASI bypass with Braun anastomosis (BTB) (n = 12), esojejunostomy (EJ) (n = 12), and SHAM (n = 8) surgery. During the 12-week follow-up period, weight changes, glucose improvement, and changes in serum nutrition were evaluated. Histological expression and bile acid concentration in the rats in all groups were also evaluated. No significant differences in weight loss and glucose improvements were observed in the RYTB, SASI, and BTB groups. The RYTB and BTB groups had significantly lower bile acid concentration and albumin levels than the SASI group. In addition, mucosal height in the RYTB and BTB groups was significantly lower than in the SASI group. Braun anastomosis had a significant effect on anti-reflux. BTB may be a superior primary procedure due to its potential for parallel bariatric and metabolic improvements, effective anti-reflux effects, simplified operations, and avoidance of severe malnutrition. Further clinical studies are needed to confirm these findings.

Embracing the Pros and Cons of the New Weight Loss Medications (Semaglutide, Tirzepatide, Etc.)

PURPOSE OF REVIEW

The history of multiple weight loss medications has been a concerning paradox based on an increased cardiovascular risk despite significant reductions in adipose tissue and weight. A new class of weight loss medications could change this past narrative based on early preliminary results of cardiovascular risk (not events-still need to be determined) and weight reduction in non-diabetics that acutely competes with results achieved with bariatric surgery. The purpose of this review is to provide a comprehensive summary of the advantages and disadvantages of these newer medications, and how they could impact urology.

RECENT FINDINGS

Weight loss of - 15 to - 20% compared to baseline has become plausible in the short-term and preliminary guidance to reduce acute and chronic adverse events are receiving attention. However, the cost, access, conflicts of interest, supply chain, life-long adherence issues, and the long-term diverse implications on mental and physical health when exposed to this class of medications (GLP-1 agonists) are unknown. The profound caloric reductions should also result in baseline or ongoing nutritional deficiency testing, and general and specific dietary recommendations, which could theoretically mimic some bariatric surgery pre- and post-surgical protocols but has yet to be studied. Regardless, the potential impact of these medicines within a variety of medical specialties needs clinical research. Current and future lifestyle interventions, dietary patterns, and medicines in the weight loss category need to be held to a paradigm whereby cardiovascular health should improve with significant weight loss without a negative impact on mental health. In urology, the ability to impact cancer risk, ED, FSD, incontinence, infertility, nephrolithiasis, and multiple other endpoints are plausible (based on bariatric surgery data) but need preliminary clinical research. Other medicines with a similar or even larger potential impact are in clinical trials, and thus, a concise overview for clinicians and researchers was needed for objective guidance. Currently, comprehensive lifestyle changes utilized with and without these medications continue to garner positive mental, physical, and legacy effects, which suggest that they are as necessary as ever in the treatment of the numerous conditions impacted by unhealthy weight gain.

Diagnosis and management of post-bariatric surgery hypoglycemia

INTRODUCTION

While bariatric surgery remains the most effective treatment for obesity that allows substantial weight loss with improvement and possibly remission of obesity-associated comorbidities, some postoperative complications may occur. Managing physicians need to be familiar with the common problems to ensure timely and effective management. Of these complications, postoperative hypoglycemia is an increasingly recognized complication of bariatric surgery that remains underreported and underdiagnosed.

AREA COVERED

This article highlights the importance of identifying hypoglycemia in patients with a history of bariatric surgery, reviews pathophysiology and addresses available nutritional, pharmacological and surgical management options. Systemic evaluation including careful history taking, confirmation of hypoglycemia and biochemical assessment is essential to establish accurate diagnosis. Understanding the weight-dependent and weight-independent mechanisms of improved postoperative glycemic control can provide better insight into the causes of the exaggerated responses that lead to postoperative hypoglycemia.

EXPERT OPINION

Management of post-operative hypoglycemia can be challenging and requires a multidisciplinary approach. While dietary modification is the mainstay of treatment for most patients, some patients may benefit from pharmacotherapy (e.g. GLP-1 receptor antagonist); Surgery (e.g. reversal of gastric bypass) is reserved for unresponsive severe cases. Additional research is needed to understand the underlying pathophysiology with a primary aim in optimizing diagnostics and treatment options.

The role of weight control in the management of type 2 diabetes mellitus: Bariatric surgery

Diabetes mellitus is one of the major epidemics in the United States. It is heavily associated with obesity and multiple metabolic derangements that lead to long term morbidity, mortality as well as financial burden. Although medical therapy has been the mainstay in the management of diabetes mellitus, there remains a large portion of this patient population which struggles to obtain adequate glycemic control and long-term weight control with medical management alone. Bariatric surgery is a powerful tool in combating diabetes mellitus and affects glucose homeostasis through a variety of pathways. While it does provide a durable pathway for weight loss, improvement in glucose homeostasis is not only affected by the weight loss seen after bariatric surgery. Changes in gut hormone secretion, insulin regulation, and gut microbial composition also affect how these operations improve glucose homeostasis. Through improvement in the management of diabetes mellitus, comorbidities including cardiovascular disease, in turn demonstrate improvement. In this article, we will discuss the role of bariatric (metabolic) surgery as it relates to long term weight loss and the impact that weight loss has on improvement in diabetes mellitus.

Pregnancy after Bariatric Surgery: Nutrition Recommendations and Glucose Homeostasis: A Point of View on Unresolved Questions

Obesity is increasing in all age groups and, consequently, its incidence has also risen in women of childbearing age. In Europe, the prevalence of maternal obesity varies from 7 to 25%. Maternal obesity is associated with short- and long-term adverse outcomes for both mother and child, and it is necessary to reduce weight before gestation to improve maternal and fetal outcomes. Bariatric surgery is an important treatment option for people with severe obesity. The number of surgeries performed is increasing worldwide, even in women of reproductive age, because improving fertility is a motivating factor. Nutritional intake after bariatric surgery is dependent on type of surgery, presence of symptoms, such as pain and nausea, and complications. There is also a risk of malnutrition after bariatric surgery. In particular, during pregnancy following bariatric surgery, there is a risk of protein and calorie malnutrition and micronutrient deficiencies due to increased maternal and fetal demand and possibly due to reduction of food intake (nausea, vomiting). As such, it is necessary to monitor and manage nutrition in pregnancy following bariatric surgery with a multidisciplinary team to avoid any deficiencies in each trimester and to ensure the well-being of the mother and fetus.

Postprandial hypoglycemia after ileocolic interposition and Billroth-II gastrojejunostomy: A case report

Postprandial reactive hypoglycemia, or late dumping syndrome, is a common but underrecognized complication from bypass surgery. We report an unusual case of postprandial reactive hypoglycemia in a patient with a severe esophageal stricture from corrosive agent ingestion who underwent ileocolic interposition and an antecolic Billroth-II gastrojejunostomy. A 22-year-old male patient with a one-year history of corrosive ingestion was referred to the hospital for a surgical correction of severe esophageal stricture. After the patient underwent ileocolic interposition and an antecolic Billroth-II gastrojejunostomy, he experienced multiple episodes of gastroesophageal refluxsymptoms during nasogastric feeding and had onset of hypoglycemic symptoms. His plasma glucose level was 59 mg/dL. After we had intraoperatively re-inserted a jejunostomy tube bypassing the ileocolic interposition, and reintroduced enteral nutrition, his hypoglycemic symptoms resolved. We performed a mixed meal tolerance test by nasogastric tube, but the results did not show postprandial hypoglycemia. Although the specific mechanism is unclear, this case suggests gastroesophageal reflux to the ileal interposition may have caused a state of exaggerated hyperinsulinemic response and rebound hypoglycemia. To the best of our knowledge, we are the first to report case of postprandial hypoglycemia after ileocolic interposition, which may have been caused by exaggerated hyperinsulinemic response due to gastroesophageal reflux to the ileal interposition. This syndrome should be considered in the patient who has had ileocolic interposition surgery and has developed postprandial hypoglycemia.

Roux-en-Y Gastric Bypass Increases Glycemic Excursions During Pregnancy and Postpartum: A Prospective Cohort Study

OBJECTIVE

Roux-en-Y gastric bypass (RYGB) and pregnancy markedly alter glucose metabolism, but evidence on glucose metabolism in pregnancy after RYGB is limited. Thus, the aims of the Bariatric Surgery and Consequences for Mother and Baby in Pregnancy study were to investigate interstitial glucose (IG) profiles during pregnancy, risk factors associated with hypoglycemia, and the association between fetal growth and hypoglycemia in pregnant women previously treated with RYGB, compared with control participants.

RESEARCH DESIGN AND METHODS

Twenty-three pregnant women with RYGB and 23 BMI- and parity-matched pregnant women (control group) were prospectively studied with continuous glucose monitoring in their first, second, and third trimesters, and 4 weeks postpartum. Time in range (TIR) was defined as time with an IG level of 3.5-7.8 mmol/L.

RESULTS

Women with RYGB were 4 years (interquartile range [IQR] 0-7) older than control participants. Pregnancies occurred 30 months (IQR 15-98) after RYGB, which induced a reduction in BMI from 45 kg/m2 (IQR 42-54) presurgery to 32 kg/m2 (IQR 27-39) prepregnancy. Women with RYGB spent decreased TIR (87.3-89.5% vs. 93.3-96.1%; P < 0.01) owing to an approximately twofold increased time above range and increased time below range (TBR) throughout pregnancy and postpartum compared with control participants. Women with increased TBR had a longer surgery-to-conception interval, lower nadir weight, and greater weight loss after RYGB. Finally, women giving birth to small-for-gestational age neonates experienced slightly increased TBR.

CONCLUSIONS

Women with RYGB were more exposed to hypoglycemia and hyperglycemia during pregnancy compared with control participants. Further research should investigate whether hypoglycemia during pregnancy in women with RYGB is associated with decreased fetal growth.

Analysis of the Efficacy and the Long-term Metabolic and Nutritional Status of Sleeve Gastrectomy with Transit Bipartition Compared to Roux-en-Y Gastric Bypass in Obese Rats

PURPOSE

Sleeve gastrectomy with transit bipartition (SG-TB) could be an attractive alternative to Roux-en-Y gastric bypass (RYGB) on weight loss and improvement of comorbidities in patients with obesity. However, there is little long-term data. Translational research on a rat model could allow long-term projection to assess efficacy and safety of SG-TB. The aim of this research was to evaluate the long-term efficacy and safety of SG-TB compared to RYGB and SHAM in rat model.

MATERIALS AND METHODS

Ninety-four male obese Wistar rats were distributed into 3 groups: SG-TB (n = 34), RYGB (n = 32), and SHAM (control group, n = 28). The percentage of total weight loss (%TWL), coprocalorimetry, glucose and insulin tolerance test, insulin, GLP-1, PYY, and GIP before and after surgery were assessed. The animals were followed over 6 months (equivalent to 16 years in humans).

RESULTS

At 6 months, %TWL was significantly greater(p = 0.025) in the SG-TB group compared to the RYGB group. There was no difference between the groups (p = 0.86) in malabsorption 15 and 120 days postoperatively. Glucose tolerance was significantly improved (p = 0.03) in the SG-TB and RYGB groups compared to the preoperative state. Insulin secretion, at 3 months, was significantly more important in the SG-TB group (p = 0.0003), compared to the RYGB and SHAM groups. GLP-1 secretion was significantly increased in the SG-TB and RYGB groups compared to the preoperative state (p = 0.001) but similar between SG-TB and RYGB animals (p = 0.72).

CONCLUSION

In a rat model, at long term compared to RYGB, SG-TB provides greater and better-maintained weight loss and an increased insulin secretion without impairing nutritional status.

Investigating relationships between post-prandial gut hormone responses and taste liking ratings prior to and following bariatric surgery: a pilot study

BACKGROUND

Alterations in gut hormone secretion and reported changes in taste preferences have been suggested to contribute to the weight-reducing effects of bariatric surgery. However, a link between changes in gut hormone secretion and taste preferences following bariatric surgery has yet to be elucidated.

METHODS

Here we examined the potential relationships between gut hormone responses (GLP-1 and PYY3-36 peak, ghrelin trough) to a test meal of Ensure and liking ratings for taste mixtures varying in sugar and fat content before and following bariatric surgery (vertical sleeve gastrectomy (VSG): N = 4; Roux-en Y gastric bypass (RYGB): N = 8).

RESULTS

Significant increases in GLP-1 and PYY3-36 peak and a significant drop in ghrelin trough were observed following surgery. Pre- and postoperation, patients with higher postprandial GLP-1 or PYY3-36 peaks gave lower liking ratings for mixtures containing a combination of fat and sugar (half and half + 20% added sugar) whereas, for the combined surgery analyses, no relationships were found with solutions comprised of high fat (half and half + 0% sugar), predominantly high sugar (skim milk + 20% added sugar), or low fat and low sugar (skim milk + 0% added sugar). Within the RYGB patients, patients with the greatest increase in postprandial GLP-1 peak from preoperation to postoperation also demonstrated the greatest decrease in liking for half & half + 20% added sugar and skim milk + 20% added sugar, but not the unsweetened version of each solution. No pre- or postoperative relationship between ghrelin and liking ratings were observed.

CONCLUSION

Gut hormone responses following bariatric surgery may contribute to taste processing of sugar+fat mixtures and together influence weight loss.

Potential Roles of Glucagon-Like Peptide 1 Receptor Agonists (GLP-1 RAs) in Nondiabetic Populations

Glucagon-like peptide 1 receptor agonists (GLP-1 RAs) have been observed in several large cardiovascular outcome trials to significantly reduce the incidence of major cardiovascular event (MACE) with type 2 diabetic patients. The clinical trials of GLP-1 RAs, including lixisenatide, exenatide, liraglutide, semaglutide, albiglutide, and dulaglutide, are associated with a significantly 14% lower risk of MACE in patients with T2DM and a history of CV disease, and with a nonsignificantly 6% lower risk in patients without history of CV disease. Some of the interpretation with GLP-1 RA trials suggested the possible role of glucagon-like peptide-1 receptor agonists (GLP-1 RAs) in primary prevention of cardiovascular diseases in nondiabetic individual, echoed by a recent editorial redefining the role of GLP-1 RAs being beyond glycaemic control. The narrative review provides an in-depth insight into GLP-1 RA use guideline in different countries and regions of the world and examines the safety and concern of GLP-1 RA use. The narrative review draws the comparison of GLP-1 RA use between diabetic and nondiabetic individual in terms of cardiovascular and metabolic benefits and points out the direction of future clinical trials of GLP-1 RAs in nondiabetic individuals. The focus of the review is on GLP-1 RAs' preventive roles in nondiabetic individuals with cardiovascular disease, chronic kidney diseases, obesity, dyslipidaemia, hypertension, nonalcoholic fatty liver diseases, polycystic ovarian syndrome (PCOS), and perioperative complications of bariatric surgery, albeit in small studies and subset analysis of clinical trials of diabetic patients.

Hypoglycemia in Pregnancies Following Gastric Bypass-a Systematic Review and Meta-analysis

The aims of this systematic review were to identify the prevalence of hypoglycemia among pregnant women treated with gastric bypass, and risk factors of hypoglycemic events in pregnancy. We searched MEDLINE, EMBASE, Cochrane, and Scopus databases from inception to April 6, 2021. Six studies investigating glucose metabolism in pregnancy following gastric bypass were included (n = 330). As assessed by the oral glucose tolerance test and continuous glucose monitoring, 57.6% (95% CI [40.1, 75.1]) of women with gastric bypass were exposed to hypoglycemia during pregnancy. No studies performed the mixed meal test, and no studies reported on risk factors associated with hypoglycemia. Further studies are required to determine the magnitude of hypoglycemia in these women's everyday-life using continuous glucose monitoring and mixed meal test.

Comparison of the Outcomes of Single Anastomosis Duodeno-Ileostomy with Sleeve Gastrectomy (SADI-S), Single Anastomosis Sleeve Ileal (SASI) Bypass with Sleeve Gastrectomy, and Sleeve Gastrectomy Using a Rodent Model with Diabetes

OBJECTIVE

Single anastomosis duodeno-ileostomy with sleeve gastrectomy (SADI-S) is a powerful form of bariatric surgery; however, it has a high risk of malnutrition. Single anastomosis sleeve ileal (SASI) bypass with sleeve gastrectomy may be used as an alternative procedure to avoid malnutrition associated with SADI-S; however, no comparison between the two procedures has been performed.

METHODS

Sprague-Dawley rats with diabetes (n = 32) were divided into four groups: SADI-S (n = 8), SASI (n = 8), SG (n = 8), and SHAM (n = 8). Body weight, food intake, and fasting blood glucose were measured, and the oral glucose tolerance test (OGTT) and insulin tolerance test (ITT) were performed before and after surgery. Blood samples were collected before and after the surgery to assess the levels of glucagon-like peptide-1 (GLP-1), hemoglobin, albumin, vitamin B12, calcium, and iron.

RESULTS

The SADI-S and SASI groups showed significantly greater weight loss and better glucose control than the SG group postoperatively. The SADI-S and SASI groups showed similar improvements in glucose control throughout the study. The SADI-S and SASI groups had significantly higher GLP-1 levels than the SG group at 6 months. The SADI-S and SASI groups presented with various degrees of deficiencies, with the SADI-S group showing a higher risk for hypoalbuminemia and iron deficiency than the SASI group.

CONCLUSIONS

The SASI procedure may be a better alternative as it has excellent bariatric and metabolic results with lower risk for hypoalbuminemia and can be easily converted into either SADI-S or SG procedures. Nevertheless, further clinical results are needed.

Effect of Bariatric Surgery on Metabolic Diseases and Underlying Mechanisms

Obesity is a highly prevalent public health concern, attributed to multifactorial causes and limited in treatment options. Several comorbidities are closely associated with obesity such as the development of type 2 diabetes mellitus (T2DM), cardiovascular and cerebrovascular diseases, and nonalcoholic fatty liver disease (NAFLD). Bariatric surgery, which can be delivered in multiple forms, has been remarked as an effective treatment to decrease the prevalence of obesity and its associated comorbidities. The different types of bariatric surgery create a variety of new pathways for food to metabolize in the body and truncate the stomach's caliber. As a result, only a small quantity of food is tolerated, and the body mass index noticeably decreases. This review describes the improvements of obesity and its comorbidities following bariatric surgery and their mechanism of improvement. Additionally, endocrine function improvements after bariatric surgery, which contributes to the patients' health improvement, are described, including the role of glucagon-like peptide-1 (GLP-1), fibroblast growth factors 19 and 21 (FGF-19, FGF-21), and pancreatic peptide YY (PYY). Lastly, some of the complications of bariatric surgery, including osteoporosis, iron deficiency/anemia, and diarrhea, as well as their potential mechanisms, are described.

The impact of preoperative glycated hemoglobin (HbA1c) on postoperative complications after elective major abdominal surgery: a meta-analysis

Background

Diabetes is a risk factor for postoperative complications. Previous meta-analyses have shown that elevated glycated hemoglobin (HbA1c) levels are associated with postoperative complications in various surgical populations. However, this is the first meta-analysis to investigate the association between preoperative HbA1c levels and postoperative complications in patients undergoing elective major abdominal surgery.

Methods

PRISMA guidelines were adhered to for this study. Six databases were searched up to April 1, 2020. Primary studies investigating the effect of HbA1c levels on postoperative complications after elective major abdominal surgery were included. Risk of bias and quality of evidence assessments were performed. Data were pooled using a random effects model. Meta-regression was performed to evaluate different HbA1c cut-off values.

Results

Twelve observational studies (25,036 patients) were included. Most studies received a ‘good’ and ‘moderate quality’ score using the NOS and GRADE, respectively. Patients with a high HbA1c had a greater risk of anastomotic leaks (odds ratio [OR]: 2.80, 95% CI [1.63, 4.83], P < 0.001), wound infections (OR: 1.21, 95% CI [1.08, 1.36], P = 0.001), major complications defined as Clavien-Dindo [CD] 3–5 (OR: 2.16, 95% CI [1.54, 3.01], P < 0.001), and overall complications defined as CD 1–5 (OR: 2.12, 95% CI [1.48, 3.04], P < 0.001).

Conclusions

An HbA1c between 6% and 7% is associated with higher risks of anastomotic leaks, wound infections, major complications, and overall postoperative complications. Therefore, guidelines with an HbA1c threshold > 7% may be putting pre-optimized patients at risk. Future randomized controlled trials are needed to explore causation before policy changes are made.

Unklare Lymphadenopathie mit Panzytopenie bei einer Patientin mit rezidivierenden Hypoglykämien

Eine Patientin wurde aufgrund rezidivierender postprandialer Hypoglykämien nach Roux-en-Y-Magenbypass mit Diazoxid behandelt, nachdem eine Ernährungsumstellung keine Symptomlinderung erzielt hatte. Nach Eindosierung von Diazoxid mit guter Akutverträglichkeit wurde die Patientin entlassen. Eine Woche nach Therapieeinleitung kam es zu einer Lymphadenopathie und Panzytopenie. Es fanden sich keine Hinweise auf das Vorliegen eines Infekts. Nach Absetzen von Diazoxid sistierten die Beschwerden. Unser Fallbericht weist auf seltene unerwünschte hämatologische Arzneimittelwirkungen unter Diazoxid hin.

The relation between postprandial glucagon-like peptide-1 release and insulin sensitivity before and after bariatric surgery in humans with class II/III obesity

BACKGROUND

Glucagon-like peptide-1 (GLP-1) receptor agonist treatment is beneficial for the human glucose metabolism, and GLP-1 secretion is greatly enhanced following Roux-en-Y gastric bypass (RYGB).

OBJECTIVES

To elucidate the relationship between GLP-1 concentrations and insulin sensitivity in subjects with class II/III obesity without diabetes and to assess the relation between GLP-1 and the improvements in glucose metabolism following RYGB.

SETTING

Clinical research facility in a university hospital.

METHODS

We recruited 35 patients scheduled for RYGB and assessed their plasma GLP-1, insulin, and glucose responses to a high-fat mixed meal. Basal and insulin-mediated glucose fluxes were determined during a 2-step hyperinsulinemic-euglycemic clamp with stable isotope-labeled tracers. Out of 35 subjects, 10 were studied both before surgery and at 1 year of follow-up.

RESULTS

Plasma GLP-1 increased following the high-fat mixed meal. Postprandial GLP-1 excursions correlated positively with hepatic and peripheral insulin sensitivity, but not with body mass index. At 1 year after RYGB, participants had lost 24% ± 6% of their body weight. Plasma GLP-1, insulin, and glucose levels peaked earlier and higher after the mixed meal. The positive association between the postprandial GLP-1 response and peripheral insulin sensitivity persisted.

CONCLUSIONS

Postprandial GLP-1 concentrations correlate with insulin sensitivity in subjects with class II/III obesity without diabetes before and 1 year after RYGB. Increased GLP-1 signaling in postbariatric patients may, directly or indirectly, contribute to the observed improvements in insulin sensitivity and metabolic health.

The role of GLP-1 in postprandial glucose metabolism after bariatric surgery: a narrative review of human GLP-1 receptor antagonist studies

The Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) bariatric procedures lead to remission or improvement of type 2 diabetes. A weight loss-independent augmentation of postprandial insulin secretion contributes to the improvement in glycemic control after RYGB and is associated with a ∼10-fold increase in plasma concentrations of the incretin hormone glucagon-like peptide-1 (GLP-1). However, the physiologic importance of the markedly increased postprandial GLP-1 secretion after RYGB has been much debated. The effect of GLP-1 receptor blockade after RYGB has been investigated in 12 studies. The studies indicate a shift toward a more prominent role for GLP-1 in postprandial β-cell function after RYGB. The effect of GLP-1 receptor antagonism on glucose tolerance after RYGB is more complex and is associated with important methodological challenges. The postprandial GLP-1 response is less enhanced after SG compared with RYGB. However, the effect of GLP-1 receptor blockade after SG has been examined in 1 study only and needs further investigation.

Comparing the Anti-diabetic Effect of Sleeve Gastrectomy with Transit Bipartition Against Sleeve Gastrectomy and Roux-en-Y Gastric Bypass Using a Diabetic Rodent Model

PURPOSE

Roux-en-Y gastric bypass (RYGB) has superior long-term diabetes remission outcomes to sleeve gastrectomy (SG). However, in regions with a high prevalence of gastric cancer, RYGB may not be the best option. This study aimed to investigate the anti-diabetic effect of SG with transit bipartition (SG-TB) compared with SG and RYGB.

MATERIALS AND METHODS

A total of 32 diabetic Sprague-Dawley rat models were assigned to one of four groups: SG (n = 8), RYGB (n = 8), SG-TB (n = 8), and SHAM (n = 8). Body weight, food intake, blood glucose, and hormonal changes (glucagon-like peptide-1 (GLP-1), insulin, and glucagon) were measured to investigate the effect of surgery in all groups. Oral glucose tolerance test and insulin tolerance test were performed before and 8 weeks after surgery.

RESULTS

There were no significant differences in the postoperative changes in body weight and food intake among the SG, RYGB, and SG-TB groups. Postoperatively, the RYGB and SG-TB groups had significantly higher GLP-1 levels and lower insulin levels than the SG group. Further, RYGB and SG-TB had significantly better glucose control improvements than SG. There were no significant differences in GLP-1, insulin, glucagon, and homeostasis model assessment of insulin resistance levels between RYGB and SG-TB. The preoperative and postoperative values of all variables in the SHAM group did not show significant differences.

CONCLUSION

In this study using a diabetes-induced rodent model, we found that the anti-diabetic effect of SG-TB is superior to that of SG and non-inferior to that of RYGB.

Impact of preoperative HbA1c on postoperative complications after elective major abdominal surgery: a systematic review protocol

INTRODUCTION

Diabetes has an increasing worldwide prevalence. It is known to be a predisposing factor for postoperative complications. Preoperative glycaemic control strategies should be pursued as glycaemic control could serve as a modifiable risk factor. Glycated haemoglobin (HbA1c), a marker of 3-month average glycaemic control, has been shown in meta-analyses to predict postoperative complications in cardiothoracic, bariatric and orthopaedic surgery. However, there is no meta-analysis in the major abdominal surgery population, in whom morbidity may be higher due to the nature of the surgery. Understanding the association between HbA1c and postoperative complications could help in preoperative risk prognostication, counselling and glycaemic target selection. The aim of this systematic review and meta-analysis is to evaluate all evidence on the association between preoperative HbA1c and postoperative complications in elective major abdominal surgery, and to investigate the threshold HbA1c level before postoperative complication rates increase.

METHODS AND ANALYSIS

This review will be performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols guidelines. PubMed, Embase, Cochrane Central Register of Controlled Trials, Google Scholar and China National Knowledge Infrastructure will be searched for all original studies. Study selection, data extraction, risk of bias and quality assessment will be conducted by two independent reviewers. The primary outcome is the association between preoperative HbA1c and major postoperative complications (Clavien Dindo 3-5), and the secondary outcome is the association between HbA1c and overall postoperative complications. Data management and synthesis will be performed using Microsoft Excel and Stata to derive pool estimates.

ETHICS AND DISSEMINATION

No ethics approval is required as only secondary data will be used. Findings will be disseminated through peer-reviewed journals and conference presentations.

PROSPERO REGISTRATION NUMBER

CRD42020167347.

Effects of dietary macronutrients and body composition on glucose homeostasis in mice

As a major health issue, obesity is linked with elevated risk of type 2 diabetes. However, whether disrupted glucose homeostasis is due to altered body composition alone, or whether dietary macronutrients play an additional role, independent of their impact on body composition, remains unclear. We investigated the associations between macronutrients, body composition, blood hormones and glucose homeostasis. We fed C57BL/6N mice 29 different diets with variable macronutrients for 12 weeks. After 10 weeks, intraperitoneal glucose tolerance tests were performed. Generalized linear models were generated to evaluate the impacts of macronutrients, body composition and blood hormones on glucose homeostasis. The area under the glucose curve (AUC) was strongly associated with body fat mass, but not dietary macronutrients. AUC was significantly associated with fasting insulin levels. Six genes from transcriptomic analysis of epididymal white adipose tissue and subcutaneous white adipose tissue were significantly associated with AUC. These genes may encode secreted proteins that play important previously unanticipated roles in glucose homeostasis.

Postprandial Hypoglycemia in Patients after Gastric Bypass Surgery Is Mediated by Glucose-Induced IL-1β

Postprandial hypoglycemia is a disabling complication of the treatment of obesity by gastric bypass surgery. So far, no therapy exists, and the underlying mechanisms remain unclear. Here, we hypothesized that glucose-induced IL-1β leads to an exaggerated insulin response in this condition. Therefore, we conducted a placebo-controlled, randomized, double-blind, crossover study with the SGLT2-inhibitor empagliflozin and the IL-1 receptor antagonist anakinra (clinicaltrials.govNCT03200782; n = 12). Both drugs reduced postprandial insulin release and prevented hypoglycemia (symptomatic events requiring rescue glucose: placebo = 7/12, empagliflozin = 2/12, and anakinra = 2/12, pval_{likelihood ratio test (LRT)} = 0.013; nadir blood glucose for placebo = 2.4 mmol/L, 95% CI 2.18-2.62, empagliflozin = 2.69 mmol/L, 95% CI 2.31-3.08, and anakinra = 2.99 mmol/L, 95% CI 2.43-3.55, pval_LRT = 0.048). Moreover, analysis of monocytes ex vivo revealed a hyper-reactive inflammatory state that has features of an exaggerated response to a meal. Our study proposes a role for glucose-induced IL-1β in postprandial hypoglycemia after gastric bypass surgery and suggests that SGLT2-inhibitors and IL-1 antagonism may improve this condition.

Changes of serum retinol-binding protein 4 associated with improved insulin resistance after laparoscopic sleeve gastrectomy in Chinese obese patients

BACKGROUND

Serum retinol-binding protein 4 (RBP4) plays a critical role in insulin resistance. The mechanism behind the impact of laparoscopic sleeve gastrectomy (LSG) on glucose metabolism is unclear. Hence, we aimed to investigate the triangle relationship between the RBP4, glucose metabolism, and LSG in patients of Chinese ethnicity.

METHODS

The study enrolled eighty-two obese patients. Glucose-lipid metabolic index, uric acid (UA), superoxide dismutase (SOD), free triiodothyronine (FT3), free thyroxin (FT4) and thyrotropin (TSH) were measured. RBP4 levels were detected by enzyme-link immunosorbent assay. 30 obese patients underwent LSG were studied. All these markers were measured again at a time interval of 3 and 6 months after surgery.

RESULTS

(1) Circulating RBP4 levels were positively associated with body mass index(BMI), blood glucose in 0 min (BG0), BG30, BG120, BG180, fasting inulin(FINS), fasting C peptide(FCP), homeostasis model of assessment for insulin resistance index (HOMA-IR), SOD, TSH and negatively associated with Matsuda index in obesity with a significant difference (P < 0.05). RBP4 levels in the patients with impaired fasting glucose (IFG), insulin resistance or hyperinsulinemia were significantly higher than the patients without IFG, insulin resistance or hyperinsulinemia (P = 0.035, P = 0.001, and P = 0.007). (2) LSG resulted in significantly decreased FBG, FINS, FCP and HOMA-IR at 3, 6 months after surgery (all P < 0.05). The RBP4 levels were significantly decreased after surgery (all P < 0.05) with no gender difference. (3) The change in RBP4 levels was significantly associated with the change in FINS, FCP, HOMA-IR, and HOMA-β at 6 months and the change in TSH at 3 months after surgery in males (all P < 0.05). The change in RBP4 levels were significantly associated with the change in FINS, FCP, HOMA-IR, HOMA-β, and TCH at 3 months after surgery in females (all P < 0.05).

CONCLUSIONS

Overall, our results interpret the significant correlations between RBP4, glucose-lipid metabolism, oxidative stress and thyroid function in obese patients. Further, the LSG brings a decline in RBP4 levels and that may contribute partly to the improved insulin resistance in obese Chinese patients.

Circulating levels of gastrointestinal hormones in response to the most common types of bariatric surgery and predictive value for weight loss over one year: Evidence from two independent trials

AIMS

Bariatric surgery leads to profound and sustainable weight loss. Gastrointestinal hormones are involved in energy and glucose homeostasis, thus postoperative changes of their circulating levels may be mediating future weight loss. To investigate how the circulating concentrations of gastrointestinal hormones change in response to the most common types of bariatric operation and whether these changes can predict future weight loss.

MATERIALS AND METHODS

We measured circulating GLP-1, GLP-2, oxyntomodulin, glicentin, glucagon, major proglucagon fragment (MPGF), ghrelin, GIP, PYY after overnight fasting and/or after a mixed meal test (MMT) in: a) 14 subjects that have undergone either an adjustable gastric banding [AGB] (n = 9) or a Roux-en-Y bypass (RYGB) (n = 5) (Pilot study 1), b) 28 subjects that have undergone either a vertical sleeve gastrectomy (n = 17) or a RYGB (n = 11) before and three, six and twelve months after surgery.

RESULTS

In addition to the expected associations with GLP-1, the most robust increases were observed in postprandial levels of oxyntomodulin and glicentin three months after VSG or RYGB (but not after AGB) and are associated with degree of weight loss. Oxyntomodulin and glicentin levels at the third and sixth month postoperative visit are positively associated with feeling of satiety which may be underlying the observed associations with future weight loss.

CONCLUSION

Beyond GLP-1, early postprandial changes in circulating oxyntomodulin and glicentin are predictors of weight loss after bariatric surgery, possibly through regulation of satiety. Further studies should focus on underlying mechanisms, and their potential as attractive therapeutic tools against obesity and related comorbidities.

Maternal, neonatal insulin resistance and neonatal anthropometrics in pregnancies following bariatric surgery

OBJECTIVE

An increasing number of women present pregnant having undergone bariatric surgery, a popular treatment for sustainable weight loss. The aim of the study was to investigate the effect, if any, of bariatric surgery on maternal and neonatal insulin resistance (IR) and neonatal body fat composition.

METHODS

Maternal IR, at 28 weeks of gestation during 2-hour 75 g oral glucose tolerance test (OGTT), neonatal IR, from umbilical cord venous blood, and neonatal birthweight and body fat composition (calculated by measuring skin folds) at birth were evaluated in 41 post-bariatric and 82 pregnant women with similar early pregnancy body mass index but no history of such surgery. Insulin resistance was assessed using the homeostasis model assessment of IR (HOMA-IR).

RESULTS

In the post-bariatric surgery group, compared to the no surgery group, maternal HOMA-IR (1.15 [1.04-2.07] vs 2.20 [1.53-3.38]; p < 0.01), neonatal birthweight (p < 0.01) and body fat (p < 0.01) were significantly lower whereas neonatal cord HOMA-IR was similar (1.29 [0.65-2.39] vs 1.19 [0.46-1.93]; p = 0.49). In the no surgery group, there was a positive correlation between maternal and neonatal HOMA-IR (p = 0.03) and between neonatal HOMA-IR and body fat (p < 0.01). However, no such significant correlations were detected in the post-bariatric surgery group.

CONCLUSION

Pregnancy following bariatric surgery is associated with a reduction in maternal IR and altered neonatal body composition with significantly lower birthweight and adiposity but no improvement in cord IR.

Development of a delayed-release nutrient for appetite control in adults with obesity and type 2 diabetes and initial clinical testing in a single dose randomized controlled trial

Background and objectives

Delivery of nutrients directly to the small intestine, either via enteral feeding tube or by gastric bypass surgery, is associated with increased levels of appetite-suppressing and glucoregulatory hormones, including GLP-1, and reduced appetite. Achieving these changes non-invasively using formulated foods may be of therapeutic benefit in individuals with obesity and related comorbidities. The aim of this pilot study was to determine the effect of a single dose of a novel delayed-release nutrient (DRN) on glucose, GLP-1, c-peptide, insulin, and appetite in adults with obesity and type 2 diabetes.

Subjects and methods

We formulated an all-natural, generally recognized as safe (‘GRAS”) DRN and conducted a randomized prospective crossover trial. Nineteen adults with obesity and type 2 diabetes underwent paired 3-h meal tolerance tests (MTT) in randomized order 1–4 weeks apart. Subjects ingested a single dose of DRN and the same nutrients as unformulated powders (UN).

Results

For DRN compared with UN, the maximal concentration (Cmax) was significantly lower for glucose, c-peptide, and insulin, and the time of maximal concentration (Tmax) was significantly delayed. While Tmax for GLP-1 was also significantly delayed following DRN compared with UN (45 min later; p = 0.26), Cmax did not differ significantly. GLP-1 rose significantly during the last 90 min of the 3-h MTT (β₁ = 0.16 pg/mL/min, p = 0.025), while following UN it decreased (β₁ = −0.21 pg/mL/min, p = 0.0026) (p difference = 0.0003). There were minimal differences in seven measures of appetite and adverse symptoms between DRN and UN.

Conclusions

We conclude that nutrient can be formulated using all-natural ingredients to induce a delayed rise in GLP-1. Further testing is needed to determine the amount and site of nutrient release, when maximum GLP-1 levels occur, and if modification of the formulation specifications and dose are associated with appetite and glucose control.

Endocrine implications of bariatric surgery: a review on the intersection between incretins, bone, and sex hormones

Bariatric surgery is now the most widely used intervention for the treatment of human obesity. A large body of literature has demonstrated its efficacy in sustained weight loss and improvement in its associated comorbidities. Here, we review the effect of bariatric surgery in gut hormone physiology, bone remodeling and the reproductive axis. Rapid improvements in insulin release and sensitivity appear to be weight loss independent and occur immediately after surgery. These effects on pancreatic beta cells are mostly due to increased gut hormone secretion due to augmented nutrient delivery to the small intestine. Bone remodeling is also affected by gut hormones. Phenotypic skeletal changes observed in mice deficient in GLP-1 or GIP suggest that increased incretins may improve bone density. However, these positive effects may be counterbalanced by the association between weight loss and a reduction in bone density. Finally, studies have shown a marked improvement following bariatric surgery in infertility and PCOS in women and hypogonadism in men. Thus, the net effect on endocrine systems after bariatric surgery will likely vary on an individual basis and depend on factors such as comorbidities, peri-menopausal state, amount of weight loss, and likelihood to adhere to vitamin supplementation after surgery.

Sleeve Gastrectomy and Roux-en-Y Gastric Bypass Achieve Similar Early Improvements in Beta-cell Function in Obese Patients with Type 2 Diabetes

Bariatric surgery is a treatment option for obese patients with type 2 diabetes mellitus (T2DM). Although sleeve gastrectomy (SG) is growing in favor, some randomized trials show less weight loss and HbA1c improvement compared with Roux-en-Y gastric bypass (RYGB). The study objective was to compare changes in beta-cell function with similar weight loss after SG and RYGB in obese patients with T2DM. Subjects undergoing SG or RYGB were studied with an intravenous glucose tolerance test before surgery and at 5–12% weight loss post-surgery. The primary endpoint was change in the disposition index (DI). Baseline BMI, HbA1c, and diabetes-duration were similar between groups. Mean total weight loss percent was similar (8.4% ± 0.4, p = 0.22) after a period of 21.0 ± 1.7 days. Changes in fasting glucose, acute insulin secretion (AIR), and insulin sensitivity (Si) were similar between groups. Both groups showed increases from baseline to post-surgery in DI (20.2 to 163.3, p = 0.03 for SG; 31.2 to 232.9, p = 0.02 for RYGB) with no significant difference in the change in DI between groups (p = 0.53). Short-term improvements in beta-cell function using an IVGTT were similar between SG and RYGB. It remains unclear if longer-term outcomes are better after RYGB due to greater weight loss and/or other factors.

Important Role of the GLP-1 Axis for Glucose Homeostasis after Bariatric Surgery

Bariatric surgery is widely used to treat obesity and improves type 2 diabetes beyond expectations from the degree of weight loss. Elevated post-prandial concentrations of glucagon-like peptide 1 (GLP-1), peptide YY (PYY), and insulin are widely reported, but the importance of GLP-1 in post-bariatric physiology remains debated. Here, we show that GLP-1 is a major driver of insulin secretion after bariatric surgery, as demonstrated by blocking GLP-1 receptors (GLP1Rs) post-gastrectomy in lean humans using Exendin-9 or in mice using an anti-GLP1R antibody. Transcriptomics and peptidomics analyses revealed that human and mouse enteroendocrine cells were unaltered post-surgery; instead, we found that elevated plasma GLP-1 and PYY correlated with increased nutrient delivery to the distal gut in mice. We conclude that increased GLP-1 secretion after bariatric surgery arises from rapid nutrient delivery to the distal gut and is a key driver of enhanced insulin secretion.

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.