Changes in gut hormone profile and glucose homeostasis after laparoscopic sleeve gastrectomy

An open-label 16-week study of liraglutide in adolescents with obesity post-sleeve gastrectomy

BACKGROUND

Up to 50% of adolescents who undergo metabolic and bariatric surgery (MBS) have obesity 3 years post-MBS, placing them at continued risk for the consequences of obesity.

OBJECTIVES

We conducted an open-label, 16-week pilot study of liraglutide in adolescents with obesity after sleeve gastrectomy (SG) to investigate liraglutide effects on weight and body mass index (BMI) post-SG.

METHODS

Adolescents aged 12-20.99 years with obesity and a history of SG ≥1 year prior were enrolled. Liraglutide was initiated at 0.6 mg/day, escalated weekly to a maximum of 3 mg/day, with treatment duration 16 weeks. Fasting laboratory assessments and an oral glucose tolerance test were performed at baseline and end-treatment.

RESULTS

A total of 43 participants were screened, 34 initiated liraglutide (baseline BMI 41.2 ± 7.7 kg/m2), and 31 (91%) attended the end-treatment visit. BMI decreased by 4.3% (p < 0.001) with liraglutide. Adolescents who had poor initial response to SG (<20% BMI reduction at BMI nadir) had less weight loss with liraglutide. Fasting glucose and haemoglobin A1C concentrations significantly decreased. There were no serious treatment-emergent adverse events reported.

CONCLUSIONS

Liraglutide treatment was feasible and associated with a BMI reduction of 4.3% in adolescents who had previously undergone SG, quantitatively similar to results obtained in adolescents with obesity who have not undergone MBS.

Post metabolic bariatric surgery weight regain: the importance of GLP-1 levels

Weight regain and insufficient weight loss are essential problems after metabolic bariatric surgery (MBS) in people living with obesity. Changes in the level of glucagon-like peptide-1 (GLP-1) secreted from the gut after bariatric surgery are one of the underlying mechanisms for successful initial weight loss. Studies and meta-analyses have revealed that postprandial GLP-1 levels increase after the Roux-en-Y gastric bypass and sleeve gastrectomy, but fasting GLP-1 levels do not increase significantly. Some observational studies have shown the relationship between higher postprandial GLP-1 levels and successful weight loss after bariatric surgery. There is growing evidence that GLP-1-receptor agonist (GLP-1-RA) use in patients who regained weight after bariatric surgery has resulted in significant weight loss. In this review, we aimed to summarize the changes in endogenous GLP-1 levels and their association with weight loss after MBS, describe the effects of GLP-1-RA use on weight loss after MBS, and emphasize metabolic adaptations in light of the recent literature. We hypothesized that maintaining higher basal-bolus GLP-1-RA levels may be a promising treatment choice in people with obesity who failed to lose weight after bariatric surgery.

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.

Effects of Roux-en-Y Gastric Bypass and Sleeve Gastrectomy on β-Cell Function at 1 Year After Surgery: A Systematic Review

Bariatric surgery is a highly effective obesity treatment resulting in substantial weight loss and improved glucose metabolism. We hereby aimed to summarize available evidence of the effect of the 2 most common bariatric surgery procedures, Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG), on dynamic measures of β-cell function (BCF). A systematic search of the literature was conducted in 3 bibliographic databases for studies reporting effects of RYGB and/or SG on BCF assessed using dynamic metabolic perturbation (oral or intravenous bolus stimulation), performed before and 1 year (±3 months) after surgery. Twenty-seven unique studies (6 randomized controlled trials and 21 observational studies), involving a total of 1856 obese adults, were included for final analysis. Twenty-five and 9 studies report effects of RYGB and SG on BCF, respectively (7 studies compared the 2 procedures). Seven studies report results according to presurgical diabetes status. Owing to variable testing procedures and BCF indices reported, no meta-analysis was feasible, and data were summarized qualitatively. For both surgical procedures, most studies suggest an increase in BCF and disposition index, particularly when using oral stimulation, with a more pronounced increase in diabetic than nondiabetic individuals. Additionally, limited indications for greater effects after RYGB versus SG were found. The quality of the included studies was, in general, satisfactory. The considerable heterogeneity of test protocols and outcome measures underscore the need for a harmonization of BCF testing in future research.

Neurohormonal Changes in the Gut–Brain Axis and Underlying Neuroendocrine Mechanisms following Bariatric Surgery

Obesity is a complex, multifactorial disease that is a major public health issue worldwide. Currently approved anti-obesity medications and lifestyle interventions lack the efficacy and durability needed to combat obesity, especially in individuals with more severe forms or coexisting metabolic disorders, such as poorly controlled type 2 diabetes. Bariatric surgery is considered an effective therapeutic modality with sustained weight loss and metabolic benefits. Numerous genetic and environmental factors have been associated with the pathogenesis of obesity, while cumulative evidence has highlighted the gut–brain axis as a complex bidirectional communication axis that plays a crucial role in energy homeostasis. This has led to increased research on the roles of neuroendocrine signaling pathways and various gastrointestinal peptides as key mediators of the beneficial effects following weight-loss surgery. The accumulate evidence suggests that the development of gut-peptide-based agents can mimic the effects of bariatric surgery and thus is a highly promising treatment strategy that could be explored in future research. This article aims to elucidate the potential underlying neuroendocrine mechanisms of the gut–brain axis and comprehensively review the observed changes of gut hormones associated with bariatric surgery. Moreover, the emerging role of post-bariatric gut microbiota modulation is briefly discussed.

MECHANISMS IN ENDOCRINOLOGY: The gut-brain axis: regulating energy balance independent of food intake

Obesity is a global pandemic with a large health and economic burden worldwide. Bodyweight is regulated by the ability of the CNS, and especially the hypothalamus, to orchestrate the function of peripheral organs that play a key role in metabolism. Gut hormones play a fundamental role in the regulation of energy balance, as they modulate not only feeding behavior but also energy expenditure and nutrient partitioning. This review examines the recent discoveries about hormones produced in the stomach and gut, which have been reported to regulate food intake and energy expenditure in preclinical models. Some of these hormones act on the hypothalamus to modulate thermogenesis and adiposity in a food intake-independent fashion. Finally, the association of these gut hormones to eating, energy expenditure, and weight loss after bariatric surgery in humans is discussed.

GLP-1-Induced AMPK Activation Inhibits PARP-1 and Promotes LXR-Mediated ABCA1 Expression to Protect Pancreatic β-Cells Against Cholesterol-Induced Toxicity Through Cholesterol Efflux

T2DM (Type 2 diabetes) is a complex, chronic disease characterized as insulin resistance and islet β-cell dysfunction. Bariatric surgeries such as Roux-en-Y gastric bypass (RYGB) surgery and laparoscopic sleeve gastrectomy (LSG) have become part of a critical treatment regimen in the treatment of obesity and T2DM. Moreover, GLP-1 increase following bariatric surgery has been regarded as a significant event in bariatric surgery-induced remission of T2DM. In this study, a high concentration cholesterol-induced lipotoxicity was observed in INS-1 cells, including inhibited cell viability and insulin secretion. Enhanced cell apoptosis and inhibited cholesterol efflux from INS-1 cells; meanwhile, ABCA1 protein level was decreased by cholesterol stimulation. Cholesterol-induced toxicity and ABCA1 downregulation were attenuated by GLP-1 agonist EX-4. GLP-1 induced AMPK phosphorylation during the protection against cholesterol-induced toxicity. Under cholesterol stimulation, GLP-1-induced AMPK activation inhibited PARP-1 activity, therefore attenuating cholesterol-induced toxicity in INS-1 cells. In INS-1 cells, PARP-1 directly interacted with LXR, leading to the poly(ADP-ribosyl)ation of LXRα and downregulation of LXR-mediated ABCA1 expression. In the STZ-induced T2DM model in rats, RYGB surgery or EX-4 treatment improved the glucose metabolism and lipid metabolism in rats through GLP-1 inhibition of PARP-1 activity. In conclusion, GLP-1 inhibits PARP-1 to protect islet β cell function against cholesterol-induced toxicity in vitro and in vivo through enhancing cholesterol efflux. GLP-1-induced AMPK and LXR-mediated ABCA1 expression are involved in GLP-1 protective effects.

Do Gut Hormones Contribute to Weight Loss and Glycaemic Outcomes after Bariatric Surgery?

Bariatric surgery is an effective intervention for management of obesity through treating dysregulated appetite and achieving long-term weight loss maintenance. Moreover, significant changes in glucose homeostasis are observed after bariatric surgery including, in some cases, type 2 diabetes remission from the early postoperative period and postprandial hypoglycaemia. Levels of a number of gut hormones are dramatically increased from the early period after Roux-en-Y gastric bypass and sleeve gastrectomy—the two most commonly performed bariatric procedures—and they have been suggested as important mediators of the observed changes in eating behaviour and glucose homeostasis postoperatively. In this review, we summarise the current evidence from human studies on the alterations of gut hormones after bariatric surgery and their impact on clinical outcomes postoperatively. Studies which assess the role of gut hormones after bariatric surgery on food intake, hunger, satiety and glucose homeostasis through octreotide use (a non-specific inhibitor of gut hormone secretion) as well as with exendin 9–39 (a specific glucagon-like peptide-1 receptor antagonist) are reviewed. The potential use of gut hormones as biomarkers of successful outcomes of bariatric surgery is also evaluated.

Effect of Laparoscopic Sleeve Gastrectomy on Static and Dynamic Measures of Glucose Homeostasis and Incretin Hormone Response 4-Years Post-Operatively

INTRODUCTION

There is limited literature available on the long-term effect of bariatric surgery especially laparoscopic sleeve gastrectomy (LSG) on the incretin hormone response.

AIM

Our primary aim was to investigate changes in glucose metabolism and incretin hormone responses in participants with impaired glucose regulation approximately 4 years after LSG. The secondary aim was to examine the long-term incretin hormone changes of biliopancreatic diversion (BPD).

METHOD

A non-randomised prospective study comprising of 10 participants undergoing LSG and 6 participants undergoing BPD. Serial measurements of glucose, insulin, C-peptide, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) were performed during an oral glucose tolerance test pre-operatively and 1 month, 6 months and at approximately 4-7 years post-operatively. Area under the curve (AUC) was examined at 60 and 120 min.

RESULTS

In the LSG group, a significant reduction in 2-h plasma glucose (2 h PG), HbA1c and HOMA-IR was observed at 4 years. Compared with pre-operative levels, significant increases in post-glucose GLP-1 secretion were observed at 1 and 6 months, but not maintained at 4 years. A linear increase was seen in post-glucose GIP response at 1 month and 6 months and 4 years. Within the BPD group, a reduction in HbA1c along with an increase GLP-1 response was observed at 7 years.

CONCLUSION

An increase in GLP-1 response was not preserved at 4 years, but a significant increase in GIP response was observed along with improved glycaemic control following LSG.

Effects of Laparoscopic Sleeve Gastrectomy on Gastric Structure and Function Documented by Magnetic Resonance Imaging Are Strongly Associated with Post-operative Weight Loss and Quality of Life: a Prospective Study

BACKGROUND

This prospective study applied magnetic resonance imaging (MRI) to assess the effect of laparoscopic sleeve gastrectomy (LSG) on gastric structure and function. The impact of these changes on patient outcomes was analyzed.

METHOD

Obese patients without gastrointestinal symptoms referred for bariatric surgery were recruited prospectively. Pre-operative assessment included (i) high-resolution manometry and pH-impedance monitoring and (ii) magnetic resonance imaging (MRI) measurement of gastric capacity, accommodation, and emptying with the 400 ml liquid Nottingham test meal (NTM). Studies were repeated 6-7 months after LSG. Weight loss and changes in the Gastrointestinal Quality of Life Index (GIQLI) assessed patient outcomes.

RESULTS

From 35 patients screened, 23 (66%) completed the study (17 females, age 36 ± 10 years, BMI 42 ± 5 kg/m2). Mean excess weight loss was 59 ± 18% at follow-up. Total gastric volume (capacity) after the meal was 467 mL (455-585 ml) before and 139 mL (121-185 ml) after LSG (normal reference 534 (419-675) mL), representing a mean 70% reduction (p < 0.0001). Similar findings were present for gastric content volume indicating rapid early-phase gastric emptying (GE) post-LSG. Conversely, late-phase GE was slower post-LSG (2.5 ± 1.0 vs. 1.4 ± 0.6 mL/min; p < 0.0001; (reference 1.5(1.4-4.9) mL/min)). Patients with ≥ 80% reduction in gastric capacity had greater weight loss (p = 0.008), but worse gastrointestinal outcomes (p = 0.023).

CONCLUSIONS

MRI studies quantified the marked reduction in gastric capacity after LSG. The reduction in capacity was associated with rapid early- but slow late-phase GE after surgery. These changes were associated with weight loss; however, reductions in gastric capacity ≥ 80% were linked to increased acid reflux and impacted on gastrointestinal quality of life.

PYY plays a key role in the resolution of diabetes following bariatric surgery in humans

BACKGROUND

Bariatric surgery leads to early and long-lasting remission of type 2 diabetes (T2D). However, the mechanisms behind this phenomenon remain unclear. Among several factors, gut hormones are thought to be crucial mediators of this effect. Unlike GLP-1, the role of the hormone peptide tyrosine tyrosine (PYY) in bariatric surgery in humans has been limited to appetite regulation and its impact on pancreatic islet secretory function and glucose metabolism remains under-studied.

METHODS

Changes in PYY concentrations were examined in obese patients after bariatric surgery and compared to healthy controls. Human pancreatic islet function was tested upon treatment with sera from patients before and after the surgery, in presence or absence of PYY. Alterations in intra-islet PYY release and insulin secretion were analysed after stimulation with short chain fatty acids (SCFAs), bile acids and the cytokine IL-22.

FINDINGS

We demonstrate that PYY is a key effector of the early recovery of impaired glucose-mediated insulin and glucagon secretion in bariatric surgery. We establish that the short chain fatty acid propionate and bile acids, which are elevated after surgery, can trigger PYY release not only from enteroendocrine cells but also from human pancreatic islets. In addition, we identify IL-22 as a new factor which is modulated by bariatric surgery in humans and which directly regulates PYY expression and release.

INTERPRETATION

This study shows that some major metabolic benefits of bariatric surgery can be emulated ex vivo. Our findings are expected to have a direct impact on the development of new non-surgical therapy for T2D correction.

Laparoscopic Sleeve Gastrectomy Significantly Increases Serum Lipoprotein Lipase Level in Obese Patients

OBJECTIVES

Obesity is one of the causes of metabolic disorders. Laparoscopic sleeve gastrectomy (LSG) confers beneficial effects not only on body weight (BW) but also on metabolic disorders. The lipoprotein lipase (LPL) level in preheparin serum is associated with visceral adipose tissue and reflects insulin resistance. However, the change in serum preheparin LPL levels after LSG remains unclear. This study aimed to examine the effect of LSG on preheparin LPL level in obese patients compared with nonsurgical treatment.

METHODS

We retrospectively reviewed a total of 100 obese patients who were treated for obesity and had preheparin LPL levels measured before and 12 months after LSG or after 12 months of nonsurgical treatment. Fifty-six patients received LSG (LSG group), and 44 patients had no surgical treatment (nonsurgical group). We compared clinical parameters such as body mass index (BMI), hemoglobin A1c (HbA1c), and preheparin LPL level before and 12 months after treatment.

RESULTS

BMI and HbA1c decreased significantly in both groups, but decreases in both parameters were greater in the LSG group than in the nonsurgical group. Estimated glomerular filtration was significantly improved only in the LSG group. Preheparin LPL level increased significantly only in the LSG group (from 45.8 ± 21.6 to 75.0 ± 34.9 ng/mL, p < 0.001). Multiple regression identified LSG and decreased BMI as independent predictors of preheparin LPL level increase.

CONCLUSIONS

These results suggest that LSG independently increases pre-heparin LPL level beyond BW reduction in obese patients.

Central Modulation of Energy Homeostasis and Cognitive Performance After Bariatric Surgery

In moderately or morbidly obese patients, bariatric surgery has been proven to be an effective therapeutic approach to control body weight and comorbidities. Surgery-mediated modulation of brain function via modified postoperative secretion of gut peptides and vagal nerve stimulation was identified as an underlying mechanism in weight loss and improvement of weight-related diseases. Increased basal and postprandial plasma levels of gastrointestinal hormones like glucagon-like peptide 1 and peptide YY that act on specific areas of the hypothalamus to reduce food intake, either directly or mediated by the vagus nerve, are observed after surgery while suppression of meal-induced ghrelin release is increased. Hormones released from the adipose tissue like leptin and adiponectin are also affected and leptin plasma levels are reduced in treated patients. Besides homeostatic control of body weight, surgery also changes hedonistic behavior in regard to food intake and cognitive performance involving the limbic system and prefrontal areas.

Metabolic and Bariatric Surgery: An Effective Treatment Option for Obesity and Cardiovascular Disease

Obesity is a chronic and debilitating disease that has become a global epidemic. Especially severe in the Unites States, obesity currently affects almost 40% of the population. Obesity has a strong causal relationship with numerous serious comorbidities that impair quality of life, shorten life expectancy, and carry a major economic burden. Obesity has particular relevance to cardiologists because it contributes directly to several major cardiovascular diseases and, consequently, increases overall cardiovascular mortality. Multiple treatment options are available, but metabolic and bariatric surgery offers the most effective and durable treatment for obesity. Moreover, metabolic and bariatric operations alleviate and often completely eliminate numerous comorbidities, particularly type 2 diabetes and other cardiovascular risk factors, such as hypertension and dyslipidemia. With their low risk of complications and morbidity, metabolic and bariatric operations significantly improve quality of life and overall survival, particularly reducing death due to cardiovascular disease.

Impact of Bariatric Surgery on Metabolic and Gut Microbiota Profile: a Systematic Review and Meta-analysis

We aim to review the available literature on obese patients treated with bariatric procedures, in order to assess their effect on the metabolic and gut microbiota profiles. A systematic literature search was performed in PubMed, Cochrane library, and Scopus databases, in accordance with the PRISMA guidelines. Twenty-two studies (562 patients) met the inclusion criteria. This study points to significant amelioration of postoperative levels of glucose, insulin, triglycerides, total cholesterol, LDL, HDL, HOMA-IR, food intake, and diabetes remission. Branched-chain amino acids (BCAAs) decreased, while trimethylamine-n-oxide (TMAO); glucagon-like peptide 1, 2 (GLP-1, GLP-2); and peptide YY (PYY) increased postoperatively. Postoperative gut microbiota was similar to that of lean and less obese objects. Well-designed randomized trials are necessary to further assess the host metabolic-microbial cross-talk after bariatric procedures.

Differences in Anthropometric and Metabolic Parameters Between Subjects with Hypoglycaemia and Subjects with Euglycaemia After an Oral Glucose Tolerance Test Six Months After Laparoscopic Sleeve Gastrectomy

BACKGROUND

Hypoglycaemia after an oral glucose tolerance test (OGTT) can occur in up to 33 % of subjects after laparoscopic sleeve gastrectomy (LSG). The underlying pathophysiology is not well understood. We aimed to compare the anthropometric and metabolic characteristics of subjects with post-OGTT hypoglycaemia (HYPO) to subjects with post-OGTT euglycaemia (EU) 6 months after LSG.

METHODS

Eighteen morbidly obese patients with normal glucose tolerance (NGT) were evaluated with an OGTT before and 6 months after LSG. Serum glucose and insulin were measured before and every 30 min after glucose ingestion up to 120'. The patients were categorized as HYPO or EU based on lowest glucose levels 90' to 120' post-OGTT 6 months after LSG (hypoglycaemia defined as glucose levels <60 mg/dl). OGTT derived indices of insulin secretion; insulin sensitivity and beta cell function were also evaluated.

RESULTS

Eight patients (44.4 %) were categorized as HYPO. Preoperatively, subjects with HYPO had lower BMI (p = 0.02) compared to that with EU. Postoperatively, subjects with HYPO had lower BMI (p = 0.01), lower weight (p = 0.01), and higher percentage of total weight loss (%TWL) (p = 0.03) compared to that with EU. The beta cell function index was higher in the HYPO group postoperatively compared to EU (p = 0.02)-especially during the latter portion of the OGTT. No difference was detected in insulin secretion and insulin sensitivity indices between the two groups preoperatively or postoperatively.

CONCLUSIONS

Subjects with NGT who developed HYPO 6 months after LSG are leaner, with higher TWL% and higher beta cell function at the latter portion of the OGTT compared to those with EU.

Sleeve Gastrectomy Decreases Body Weight, Whole-Body Adiposity, and Blood Pressure Even in Aged Diet-Induced Obese Rats

BACKGROUND

Aging and obesity are two conditions associated with increased risk of cardiovascular disease. Our aim was to analyze whether an advanced age affects the beneficial effects of sleeve gastrectomy on weight loss and blood pressure in an experimental model of diet-induced obesity (DIO).

METHODS

Young (6-month-old) and old (18-month-old) male Wistar DIO rats (n = 101) were subjected to surgical (sham operation and sleeve gastrectomy) or dietary interventions (pair-fed to the amount of food eaten by sleeve gastrectomized animals). Systolic (SBP), diastolic (DBP), and mean (MBP) blood pressure values and heart rate (HR) were recorded in conscious, resting animals by non-invasive tail-cuff plethysmography before and 4 weeks after surgical or dietary interventions.

RESULTS

Aging was associated with higher (P < 0.05) body weight and subcutaneous and perirenal fat mass as well as mild cardiac hypertrophy. Sleeve gastrectomy induced a reduction in body weight, whole-body adiposity, and serum total ghrelin in both young and old DIO rats. The younger group achieved a higher excess weight loss than the older group (164 ± 60 vs. 82 ± 17 %, P < 0.05). A significant (P < 0.05) decrease in insulin resistance, SBP, DBP, MBP, and HR without changes in heart weight was observed after sleeve gastrectomy independently of age.

CONCLUSION

Our results provide evidence for the effectiveness of sleeve gastrectomy without increased operative risk in body weight and blood pressure reduction even in aged animals via endocrine changes that go beyond the mere caloric restriction.

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.

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.

Trends in utilization of bariatric surgery, 2010-2014: sleeve gastrectomy dominates

BACKGROUND

Bariatric surgery is the most effective treatment for morbid obesity. Furthermore, the proportion of various types of bariatric procedures has significantly changed over the last two decades. Sleeve gastrectomy (SG) has been increasingly chosen as a primary bariatric procedure in recent years.

OBJECTIVES

This study aimed to analyze the changing pattern of bariatric surgery utilization from 2010 to 2014.

SETTINGS

Using the American College of Surgeons National Surgical Quality Improvement Program database from 2010 to 2014.

METHOD

We identified patients aged≥18 years with a body mass index (BMI)≥35 kg/m² undergoing primary bariatric surgery. The trend of surgical procedures was analyzed from 2010 to 2014.

RESULTS

A total of 93,328 patients were included (age of 44.6±11.8 years and BMI of 46.2±7.9 kg/m²). Roux-en-Y gastric bypass (RYGB), adjustable gastric band, and SG comprised 58.4%, 28.8%, and 9.3% of the procedures in 2010 which changed to 37.6%, 3.1%, and 58.2% in 2014, respectively. Baseline BMI of SG patients decreased from 47.5 to 45.6 kg/m² (P< .001). The proportion of diabetic patients undergoing RYGB increased (30.4% to 33.2%, P<.001) but decreased among those having SG (26.6% to 22.8%, P = .001). The proportion of patients with hypertension having RYGB remained unchanged while decreased among SG patients (56.2% to 47.6%, P<.001). Female patients among the SG group increased from 73.2% to 77.7% (P< .001).

CONCLUSION

SG has been increasingly performed in the United States superseding adjustable gastric band and RYGB. The trend is in favor of females, lower BMI, and lower ratio of patients with diabetes and hypertension. More data are needed on outcomes of SG to assess its long-term effectiveness and credibility.

Comparison of glucose homeostasis parameters between patients with high and low risk of diabetes at 6 weeks and 6 months after sleeve gastrectomy

BACKGROUND

The changes in glucose homeostasis after sleeve gastrectomy (SG) for patients with high (HRD) and low risk (LRD) of developing diabetes have not been investigated.

OBJECTIVE

To compare the glucose homeostasis parameters between patients with HRD and LRD after SG.

SETTING

University hospital in Greece.

METHODS

Thirteen patients were categorized as HRD (9 females, mean body mass index 46.3±1.6 kg/m²) and 10 as LRD (8 females, mean body mass index 45.4±1.7 kg/m²) based on a preoperative 2-hour oral glucose tolerance test (OGTT). OGTT was repeated 6 weeks and 6 months postoperatively. OGTT-derived indices of insulin secretion, insulin sensitivity, and β-cell function (oral disposition index [ODI]) were calculated.

RESULTS

Preoperatively, in the HRD group, fasting and postload glucose levels were higher and the ODIs were lower compared with those in the LRD group. Six weeks postoperatively, glucose levels and ODIs were not different between the 2 groups. However, 6 months postoperatively, the HRD group had demonstrated higher postload glucose levels and lower ODI (0-30) and ODI (0-120) compared with the LRD group. Six weeks postoperatively, insulin levels, early insulin secretion, and insulin resistance indices were decreased compared with preoperative levels only in the HRD group. Six months postoperatively, ODIs and insulin sensitivity indices improved in both groups compared with baseline.

CONCLUSION

Six months after SG, glucose levels and ODIs improved for both HRD and LRD patients; however, postprandial glucose levels and ODI (0-30) and ODI (0-120) in HRD patients did not return to LRD levels. Moreover, during the first 6 postoperative weeks, the changes in glucose homeostasis parameters compared with preoperative levels were different for HRD and LRD patients.

Sleeve gastrectomy activates the GLP-1 pathway in pancreatic β cells and promotes GLP-1-expressing cells differentiation in the intestinal tract

Db/db mouse was used to study the underlying mechanisms by which Sleeve gastrectomy (SG) improves β-cell function. We investigated β-cell function, plasma active GLP-1 levels, the GLP-1R pathway in β cells and L cell differentiation. After SG, β-cell function was significantly increased, and the GLP-1R-PKCζ-PDX-1 pathway was active in β cells. Plasma active GLP-1 levels, as well as the number of L cells in the jejunum, were significantly increased after SG. The expression of early transcription factors (TF), including Ngn3, FoxA1 and Nkx2.2, was not compromised by chronic hyperglycemia. In contrast, the expression of the downstream TF PAX6 was affected, and this down-regulation could be reversed by SG. So, SG can maintain L cell differentiation, increase plasma active GLP-1 level, sustain the activation of the GLP-1R pathway and improve β cell function in Db/db mice. Our results show that SG can overall improve the function of the entero-insular axis.

Physiology, pathophysiology and therapeutic implications of enteroendocrine control of food intake

With the increasing prevalence of obesity and its associated comorbidities, strides to improve treatment strategies have enhanced our understanding of the function of the gut in the regulation of food intake. The most successful intervention for obesity to date, bariatric surgery effectively manipulates enteroendocrine physiology to enhance satiety and reduce hunger. Areas covered: In the present article, we provide a detailed overview of the physiology of enteroendocrine control of food intake, and discuss its pathophysiologic correlates and therapeutic implications in both obesity and gastrointestinal disease. Expert commentary: Ongoing research in the field of nutrient sensing by L-cells, as well as understanding the role of the microbiome and bile acid signaling may facilitate the development of novel strategies to combat the rising population health threat associated with obesity. Further refinement of post-prandial satiety gut hormone based therapies, including the development of chimeric peptides exploiting the pleiotropic nature of the gut hormone response, and identification of novel methods of delivery may hold the key to optimization of therapeutic modulation of gut hormone physiology in obesity.

Recent advances in metabolic and bariatric surgery

Obesity and its associated medical conditions continue to increase and add significant burden to patients, as well as health-care systems, worldwide. Bariatric surgery is the most effective treatment for severe obesity and its comorbidities, and resolution of diabetes is weight loss-independent in the case of some operations. Although these weight-independent effects are frequently described clinically, the mechanisms behind them are not well understood and remain an intense area of focus in the growing field of metabolic and bariatric surgery. Perceptions of the mechanisms responsible for the beneficial metabolic effects of metabolic/bariatric operations have shifted from being mostly restrictive and malabsorption over the last 10 to 15 years to being more neuro-hormonal in origin. In this review, we describe recent basic and clinical findings of the major clinical procedures (adjustable gastric banding, vertical sleeve gastrectomy, Roux-en-Y gastric bypass, and biliopancreatic diversion) as well as other experimental procedures (ileal interposition and bile diversion) that recapitulate many of the metabolic effects of these complex operations in a simpler fashion. As the role of bile acids and the gut microbiome on metabolism is becoming increasingly well described, their potential roles in these improvements following metabolic surgery are becoming better appreciated. Bile acid and gut microbiome changes, in light of recent developments, are discussed in the context of these surgical procedures, as well as their implications for future study.

From bariatric to metabolic surgery: Looking for a “disease modifier” surgery for type 2 diabetes

In this review the recent evolution of the comprehension of clinical and metabolic consequences of bariatric surgery is depicted. At the beginning bariatric surgery aim was a significant and durable weight loss. Later on, it became evident that bariatric surgery was associated with metabolic changes, activated by unknown pathways, partially or totally independent of weight loss. Paradigm of this “metabolic” surgery is its effects on type 2 diabetes mellitus (T2DM). In morbid obese subjects it was observed a dramatic metabolic response leading to decrease blood glucose, till diabetes remission, before the achievement of clinically significant weight loss, opening the avenue to search for putative anti-diabetic “intestinal” factors. Both proximal duodenal (still unknown) and distal (GLP1) signals have been suggested as hormonal effectors of surgery on blood glucose decrease. Despite these findings T2DM remission was never considered a primary indication for bariatric surgery but only a secondary one. Recently T2DM remission in obese subjects with body mass index (BMI) greater than 35 has become a primary aim for surgery. This change supports the idea that “metabolic surgery” definition could more appropriate than bariatric, allowing to explore the possibility that metabolic surgery could represent a “disease modifier” for T2DM. Therefore, several patients have undergone surgery with a primary aim of a definitive cure of T2DM and today this surgery can be proposed as an alternative therapy. How much surgery can be considered truly metabolic is still unknown. To be truly “metabolic” it should be demonstrated that surgery could cause T2DM remission not only in subjects with BMI > 35 but also with BMI < 35 or even < 30. Available evidence on this topic is discussed in this mini-review.

Surgical Management of Metabolic Syndrome Related to Morbid Obesity

Current treatment approaches in morbid obesity are multimodal in nature. Combination therapies include increases in moderate-intensity aerobic and resistance exercise; behavioral lifestyle changes to increase compliance with diet and activity recommendations; medical nutrition therapy; intensive medical therapy; and metabolic surgical procedures, such as gastric bypass and vertical sleeve gastrectomy. This article focuses on the preoperative evaluation and proper patient selection for metabolic surgery. The procedures are discussed relative to their anatomy, metabolic mechanism of action, and common adverse effects.

Alternate current biosusceptometry for the assessment of gastric motility after proximal gastrectomy in rats: a feasibility study

BACKGROUND

This study proposes an experimental model to assess the consequences of gastric surgeries on gastric motility. We investigated the effects of proximal gastrectomy (PG) using a non-invasive technique (alternate current biosusceptometry [ACB]) on gastric contractility (GC), gastric emptying (GE), and orocecal transit (OCT) after the ingestion of liquids and solids in rats.

METHODS

Twenty-four male rats were subjected to gastric motility assessment before and after the PG procedure. The GE and OCT results are expressed as the mean time of gastric emptying (MGET) and cecum arrival (MCAT). The GC recordings are presented as the frequency and amplitude of contractions.

KEY RESULTS

Mean time of gastric emptying after solid meals were significantly different (p < 0.001) between control and PG (113 ± 5 to 99 ± 6 min). Mean time of cecum arrival ranged from 265 ± 9 to 223 ± 11 min (p < 0.001) and 164 ± 9 to 136 ± 17 min (p < 0.050) for solid and liquid meals, respectively. The assessment of GC showed that surgery decreased the phasic frequency (4.4 ± 0.4 to 3.0 ± 1.1 cpm, p < 0.050) and increased the amplitude of contractions (3.6 ± 2.7 to 7.2 ± 3.0 V/s, p < 0.050). No significant difference was found in tonic frequency.

CONCLUSIONS & INFERENCES

The ACB system was able to assess GE, OCT, and GC in gastrectomized rats. Overall, PG accelerated GE and gastrointestinal transit, likely due to the increase in both intragastric pressure and amplitude contraction. Our data presented an efficient model to investigate functional consequences from gastric surgeries that will allow further studies involving different procedures.

Bariatric and metabolic surgery: a shift in eligibility and success criteria

The obesity epidemic, combined with the lack of available and effective treatments for morbid obesity, is a scientific and public health priority. Worldwide, bariatric and metabolic surgeries are increasingly being performed to effectively aid weight loss in patients with severe obesity, as well as because of the favourable metabolic effects of the procedures. The positive effects of bariatric surgery, especially with respect to improvements in type 2 diabetes mellitus, have expanded the eligibility criteria for metabolic surgery to patients with diabetes mellitus and a BMI of 30-35 kg/m(2). However, the limitations of BMI, both in the diagnosis and follow-up of patients, need to be considered, particularly for determining the actual adiposity and fat distribution of the patients following weight loss. Understanding the characteristics shared by bariatric and metabolic surgeries, as well as their differential aspects and outcomes, is required to enhance patient benefits and operative achievements. For a holistic approach that focuses on the multifactorial effects of bariatric and metabolic surgery to be possible, a paradigm shift that goes beyond the pure semantics is needed. Such a shift could lead to profound clinical implications for eligibility criteria and the definition of success of the surgical approach.

Laparoscopic sleeve gastrectomy in Asia: Long term outcome and revisional surgery

BACKGROUND

Laparoscopic sleeve gastrectomy (LSG) is a popular stand-alone bariatric surgery, despite a paucity of long-term data. Hence, this study is to report the long-term outcome of LSG as primary bariatric procedure and the result of revisional surgery.

METHODS

With retrospective analysis of a prospective bariatric database, participants who defaulted clinic follow-up were interviewed by telephone. A total of 667 LSG was performed as primary bariatric procedure (2006-2012) with mean age of 34.5 ± 9.7 years old, female 74.7%, mean body mass index (BMI) 37.3 ± 8.1 kg/m(2). A 36-F bougie was used for all cases.

RESULTS

There were 61 patients available with long-term data. The weight loss outcome at 1 year, 2 years, 3 years, 4 years, and 5 years showed a mean BMI 26.3, 25.2, 25.3, 27.1, and 26.2 with mean excess weight loss (EWL) 76.0%, 79.6%, 77.3%, 73.4%, and 72.6% respectively. However, 17% patients developed de novo gastro-esophageal reflux disease (GERD). Eighteen patients (2.2%) needed surgical revisions due to weight regain (n = 6), persistent type 2 diabetes mellitus (T2DM; n = 2), stricture (n = 2), and GERD (n = 8). The revision resulted in an additional mean excess weight loss of 23.8% with mean BMI 24.9 kg/m(2) at 6 months postoperatively. There was a 23.7% mean reduction of HbA1c with one patient who was in complete diabetic remission at 1 year.

CONCLUSION

Our results showed LSG is a durable bariatric procedure with > 70% EWL at 5 years despite a high incidence of GERD. The need for revision of LSG is low and mainly for GERD.

Metabolic changes induced by the biliopancreatic diversion in diet-induced obesity in male rats: the contributions of sleeve gastrectomy and duodenal switch

The mechanisms underlying the body weight and fat loss after the biliopancreatic diversion with duodenal switch (BPD/DS) remain to be fully delineated. The aim of this study was to examine the contributions of the two main components of BPD/DS, namely sleeve gastrectomy (SG) and duodenal switch (DS), on energy balance changes in rats rendered obese with a high-fat (HF) diet. Three different bariatric procedures (BPD/DS, SG, and DS) and three sham surgeries were performed in male Wistar rats. Sham-operated animals fed HF were either fed ad libitum (Sham HF) or pair weighed (Sham HF PW) by food restriction to the BPD/DS rats. A group of sham-operated rats was kept on standard chow and served as normal diet control (Sham Chow). All three bariatric surgeries resulted in a transient reduction in food intake. SG per se induced a delay in body weight gain. BPD/DS and DS led to a noticeable gut malabsorption and a reduction in body weight and fat gains along with significant elevations in plasma levels of glucagon-like peptide-1(7-36) and peptide YY. BPD/DS and DS elevated energy expenditure above that of Sham HF PW during the dark phase. However, they reduced the volume, oxidative metabolism, and expression of thermogenic genes in interscapular brown adipose tissue. Altogether the results of this study suggest that the DS component of the BPD/DS, which led to a reduction in digestible energy intake while sustaining energy expenditure, plays a key role in the improvement in the metabolic profile led by BPD/DS in rats fed a HF diet.

Routine postoperative upper gastrointestinal fluoroscopy after laparoscopic sleeve gastrectomy: Is there still a utility?

PURPOSE

To assess the performance of routine esophagogastric transit studies (OGT) performed between day 2 (D2) and day 4 (D4) following sleeve gastrectomy for the diagnosis of gastric fistula.

PATIENTS AND METHODS

Single center study including 736 patients undergoing surgery for sleeve gastrectomy including 32 of whom developed gastric fistula. Seven hundred and twenty OGT on D2 and 86 abdominal and pelvic CT scans were performed to investigate for a fistula and whether or not a blood collection was present. Sensitivity, specificity, positive and negative predictive values, Youden index (YI) and dosimetry were calculated for both investigations.

RESULTS

The sensitivity and specificity of OGT for the diagnosis of fistula were 7% and 98% respectively with a PPV of 18%, an NPV of 96% and YI of 0.06. The mean DSP was 5500μGy.m(2). Sensitivity, specificity, positive and negative predictive values and Youden index for CT were 55%, 100%, 100%, 81%, 0.55, respectively for the presence of a fistula; and 96%, 86%, 78%, 98%, 0.83 for the presence of a non-blood collection and; 100%, 86%, 78%, 100%, 0.86 for the presence of a non-blood collection and/or fistula. The mean DLP was 3700 mGy.cm.

CONCLUSION

Because of its very poor sensitivity for the diagnosis of gastric fistula, the OGT on D2 needs to be reconsidered. CT performed on clinical suspicion appears to be a better diagnostic tool.

The effect of surgically induced weight loss on nonalcoholic fatty liver disease in morbidly obese Indians: "NASHOST" prospective observational trial

BACKGROUND

Surgically induced weight loss improves nonalcoholic fatty liver disease (NAFLD) in morbidly obese Caucasian patients. Similar data are lacking from India.

OBJECTIVE

To compare the histologic features of NAFLD in morbidly obese Indian patients before and 6 months after bariatric surgery. Histologic changes were also separately assessed according to the type of bariatric intervention.

SETTING

Teaching institution, India; private practice.

METHODS

All patients undergoing bariatric surgery from July 2012 to July 2013 underwent a routine liver biopsy at the time of bariatric surgery. If the biopsy specimen indicated NAFLD, patients were asked to undergo a second biopsy after 6 months. Baseline anthropometry, clinical data, biochemistry, and pathology were recorded and repeated at follow-up.

RESULTS

Eighty-eight of 134 index biopsy specimens indicated NAFLD. Thirty patients had paired liver biopsies. Steatosis was present in all, 14 had lobular inflammation, 10 had ballooning degeneration, and 14 had fibrosis. Mean time between the biopsies was 7.1 months (range 6-8 months). At the second biopsy, steatosis had resolution in 19 and improvement in 11, lobular inflammation had resolution in 12 and improvement in 2, ballooning had resolution in 9 and improvement in 1 and fibrosis had resolution in 11 and improvement in 3 (P<0.05 for all). Improvement was greater among those who underwent a sleeve gastrectomy in comparison to a Roux-en-Y gastric bypass, although this difference was not statistically significant. None had worsening of liver histologic results.

CONCLUSIONS

Surgically induced weight loss significantly and rapidly improves liver histology in morbidly obese Indians with NAFLD.

Endocrine and metabolic complications after bariatric surgery

Bariatric surgery is the most effective therapeutic option for obese patients; however, it carries substantial risks, including procedure-related complications, malabsorption, and hormonal disturbance. Recent years have seen an increase in the bariatric surgeries performed utilizing either an independent or a combination of restrictive and malabsorptive procedures. We review some complications of bariatric procedures more specifically, hypoglycemia and osteoporosis, the recommended preoperative assessment and then regular follow up, and the therapeutic options. Surgeon, internist, and the patient must be aware of the multiple risks of this kind of surgery and the needed assessment and follow up.

Lipopolysaccharide and lipopolysaccharide-binding protein levels and their relationship to early metabolic improvement after bariatric surgery

BACKGROUND

Bariatric surgery usually results in metabolic improvements within a few days from intervention, but the underlying mechanism is not completely understood and may vary depending on the bariatric procedure. Lipopolysaccharides (LPS) from gut microbiota have been proposed as a triggering factor for the inflammatory state in obesity. Roux-en-Y Gastric Bypass (RYGB) leads to a LPS decrease in the medium-term.

OBJECTIVE

To analyze LPS and LPS-binding protein (LBP) in normoglycemic (NG) and diabetic morbidly obese patients in the short-term after 2 different bariatric surgery procedures.

SETTING

University Hospital, Spain.

METHODS

Fifty morbidly obese patients underwent bariatric surgery: 24 with sleeve gastrectomy (SG) and 26 with biliopancreatic diversion (BPD). Patients were classified according to their glycemic status as NG or prediabetic/diabetic. LPS and LBP levels and biochemical and anthropometric variables were determined before and at days 15 and 90 after surgery.

RESULTS

A significant LPS reduction was seen only in the prediabetic/diabetic patients at 90 days after SG. LBP levels rose at 15 days after BPD but at 90 days returned to baseline in both NG and prediabetic/diabetic patients. At 90 days after SG, LBP levels significantly decreased compared to baseline in NG and prediabetic/diabetic patients. After multivariate analysis only the change in BMI was independently associated with the change in LBP levels at 90 days. None of the changes in biochemical or anthropometrical variables were significantly associated with the changes in LPS levels at 15 days or 90 days.

CONCLUSION

This is the first study showing that the short-term LPS decrease after bariatric surgery depends on the surgical procedure used as well as on the previous glycemic status of the patient, with SG having the greatest short-term effect on LPS and LBP levels. LBP is closely related to anthropometric variables and may be an inflammatory marker in bariatric surgery patients.

Glucagon secretion after metabolic surgery in diabetic rodents

Excessive or inadequate glucagon secretion promoting hepatic gluconeogenesis and glycogenolysis is believed to contribute to hyperglycemia in patients with type 2 diabetes. Currently, metabolic surgery is an accepted treatment for obese patients with type 2 diabetes and has been shown to improve glycemic control in Goto-Kakizaki (GK) rats, a lean animal model for type 2 diabetes. However, the effects of surgery on glucagon secretion are not yet well established. In this study, we randomly assigned forty 12- to 14-week-old GK rats to four groups: control group (GKC), sham surgery (GKSS), sleeve gastrectomy (GKSG), and gastric bypass (GKGB). Ten age-matched Wistar rats served as a non-diabetic control group (WIC). Glycemic control was assessed before and 4 weeks after surgery. Fasting- and mixed-meal-induced plasma levels of insulin and glucagon were measured. Overall glycemic control improved in GKSG and GKGB rats. Fasting insulin levels in WIC rats were similar to those for GKC or GKSS rats. Fasting glucagon levels were highest in GKGB rats. Whereas WIC, GKC, and GKSS rats showed similar glucagon levels, without any significant meal-induced variation, a significant rise occurred in GKSG and GKGB rats, 30 min after a mixed meal, which was maintained at 60 min. Both GKSG and GKGB rats showed an elevated glucagon:insulin ratio at 60 min in comparison with all other groups. Surprisingly, the augmented post-procedural glucagon secretion was accompanied by an improved overall glucose metabolism in GKSG and GKGB rats. Understanding the role of glucagon in the pathophysiology of type 2 diabetes requires further research.

Development of minimally invasive techniques for management of medically-complicated obesity

The field of bariatric surgery has been rapidly growing and evolving over the past several decades. During the period that obesity has become a worldwide epidemic, new interventions have been developed to combat this complex disorder. The development of new laparoscopic and minimally invasive treatments for medically-complicated obesity has made it essential that gastrointestinal physicians obtain a thorough understanding of past developments and possible future directions in bariatrics. New laparoscopic advancements provide patients and practitioners with a variety of options that have an improved safety profile and better efficacy without open, invasive surgery. The mechanisms of weight loss after bariatric surgery are complex and may in part be related to altered release of regulatory peptide hormones from the gut. Endoscopic techniques designed to mimic the effects of bariatric surgery and endolumenal interventions performed entirely through the gastrointestinal tract offer potential advantages. Several of these new techniques have demonstrated promising, preliminary results. We outline herein historical and current trends in the development of bariatric surgery and its transition to safer and more minimally invasive procedures designed to induce weight loss.

Relationship between gut hormones and glucose homeostasis after bariatric surgery

Type 2 diabetes mellitus (T2D) is emerging as a worldwide public health problem, and is mainly associated with an increased incidence of obesity. Bariatric surgery is currently considered the most effective treatment for severely obese patients. After bariatric surgery, T2D patients have shown a significant improvement in glycemic control, even before substantial weight loss and often discontinuation of medication for diabetes control. A central role for enteroendocrine cells from the epithelium of the gastrointestinal tract has been speculated in this postoperative phenomenon. These cells produce and secrete polypeptides - gut hormones - that are associated with regulating energy intake and glucose homeostasis through modulation of peripheral target organs, including the endocrine pancreas. This article reviews and discusses the biological actions of the gut hormones ghrelin, cholecystokinin, incretins, enteroglucagon, and Peptide YY, all of which were recently identified as potential candidates for mediators of glycemic control after bariatric surgery. In conclusion, current data reinforce the hypothesis that T2D reversion after bariatric surgery may be related to glycemic homeostasis developed by the intestine.

Malabsorption plays a major role in the effects of the biliopancreatic diversion with duodenal switch on energy metabolism in rats

BACKGROUND

The mechanisms underlying the metabolic benefits of the biliopancreatic diversion with duodenal switch (BPD/DS) have not been clarified. The objective of this study was to investigate the metabolic roles of sleeve gastrectomy (SG) and duodenal switch (DS) as main surgical components of BPD/DS.

METHODS

BPD/DS, SG, and DS surgeries were performed on chow-fed nonobese Wistar rats. Weight and energy intake were recorded during 8 postsurgical weeks. Glucagon-like peptide 1 (GLP-1), peptide tyrosine-tyrosine (PYY), glucose-dependent insulinotropic peptide, and ghrelin were measured pre- and postprandially at weeks 3 and 8, after surgery. Body composition, muscle, liver, and adipose tissue weights were measured. Gut morphometry and the presence and distribution of GLP-1 and PYY (L-cells) in the gut were determined using histochemical techniques.

RESULTS

Compared with sham, BPD/DS and DS led to significant reductions in weight gain, percentage of fat, and adipose tissue weight. These effects were accompanied by a reduction in digestible energy intake associated with fecal energy loss due to DS. BPD/DS and DS produced intestinal hypertrophy, as well as higher plasma GLP-1 and PYY in both fasted and refed states. It is noteworthy that none of those alterations were observed after SG, which nonetheless led to transient postoperative reduction in gross energy intake and weight. Similar to BPD/DS, SG alone produced a reduced meal size and an enhanced postprandial depression of plasma ghrelin.

CONCLUSION

BPD/DS results in metabolic benefits, which appear largely caused by food malabsorption due to DS. The elevation of anorectic GLP-1 and PYY are additional consequences of DS, which, together with malabsorption, could promote the metabolic benefits of BPD/DS.

Metabolic surgery: action via hormonal milieu changes, changes in bile acids or gut microbiota? A summary of the literature

Obesity and type 2 diabetes remain epidemic problems. Different bariatric surgical techniques causes weight loss and diabetes remission to varying degrees. The underlying mechanisms of the beneficial effects of bariatric surgery are complex, and include changes in diet and behaviour, as well as changes in hormones, bile acid flow, and gut bacteria. We summarized the effects of multiple different bariatric procedures, and their resulting effects on several hormones (leptin, ghrelin, adiponectin, glucagon-like peptide 1 (GLP-1), peptide YY, and glucagon), bile acid changes in the gut and the serum, and resulting changes to the gut microbiome. As much as possible, we have tried to incorporate multiple studies to try to explain underlying mechanistic changes. What emerges from the data is a picture of clear differences between restrictive and metabolic procedures. The latter, in particular the roux-en-Y gastric bypass, induces large and distinctive changes in most measured fat and gut hormones, including early and sustained increase in GLP-1, possible through intestinal bile acid signalling. The changes in bile flow and the gut microbiome are causally inseparable so far, but new studies show that each contributes to the effects of weight loss and diabetes resolution.

The role of bariatric surgery in the treatment of diabetes

The obesity epidemic contributes to approximately 44% of the world's type 2 diabetes burden. Bariatric surgery is an effective treatment for type 2 diabetes mellitus in patients with morbid obesity as it improves glycaemia, blood pressure, lipids and inflammation. This review describes the evidence supporting the addition of bariatric surgery to the treatment algorithms used by diabetologists. We emphasize the need to view bariatric surgery as an adjuvant therapy which should not be used instead of but rather together with best medical therapy.

Effects of laparoscopic sleeve gastrectomy in patients with morbid obesity and metabolic disorders

PURPOSES

Obesity and its correlation with other pathological conditions determine the onset of the metabolic syndrome, which exposes the patient to a higher risk of major cardiovascular complications. Laparoscopic sleeve gastrectomy (LSG) is a bariatric surgical procedure that appears to influence both the reduction of fat mass and the action of some gastrointestinal hormones.

PATIENTS AND METHODS

Between January 2011 and July 2013, 23 patients with morbid obesity underwent LSG and follow-up. In the evaluation of patients, the criteria for metabolic syndrome given by the International Diabetes Federation were followed. A multidisciplinary team of experts evaluated patients before surgery and in subsequent scheduled postoperative visits at 7, 30, 60, and 90 days and 4, 5, 6, 9, and 12 months. Anthropometric and metabolic parameters were analyzed.

RESULTS

The mean excess weight loss was 8.57±3.02%, 17.65±6.40%, 25.47±7.90%, 33.76±9.27%, 41.83±10.71%, 46.02±13.90%, 52.60±14.05%, 58.48±16.07%, and 62.59±21.29% at 7, 30, 60, and 90 days and 4, 5, 6, 9, and 12 months, respectively. In the same observational period there was an excellent improvement of metabolic indices. None of the patients previously taking prescribed hypoglycemic drugs restarted therapy. Mean fasting plasma glucose significantly decreased compared with the preoperative values. Blood pressure had a statistically significant improvement. Modification in the lipid profile was more variable. During the period of observation 22 of 23 patients reported in this study did not fit the criteria for metabolic syndrome.

CONCLUSIONS

Morbid obesity and related diseases may benefit from a surgical approach in selected patients. Randomized controlled trials are needed to evaluate the role of LSG.

Laparoscopic sleeve gastrectomy for morbid obesity and glucose metabolism: a new perspective

BACKGROUND

Global rise in the incidence of obesity and type 2 diabetes mellitus is widely recognized as one of the most challenging contemporary threats to public health. Weight loss surgery has proven to be an effective and durable solution for morbidly obese adults. Laparoscopic sleeve gastrectomy (LSG) was introduced as a restrictive procedure for obese patients, initially described as a possible first-stage operation, but now commonly performed as a stand-alone bariatric operation for both high-risk and super-morbid-obese patients, as well as for patients with lower body mass index. This study aims to evaluate the progression of glucose metabolism in patients undergoing LSG.

METHODS

This prospective study investigated 62 patients who underwent LSG by the same surgical team in an 18-month period. Preoperative evaluation included demographic information, complete medical history including comorbidities and medication, clinical examination, evaluation of cardiopulmonary function, measurement of weight and height on a standard electronic scale, upper gastrointestinal endoscopy and upper abdominal ultrasound, as well as interviews with a psychologist and nutritionist. Glucose metabolism was evaluated by oral glucose tolerance test (OGTT), preoperatively and at 3, 6, and 12 months after surgery.

RESULTS

The OGTT was significantly ameliorated in all groups during follow-up. Nine of 12 diabetic patients (75 %) ceased drug treatment at 3 months postoperatively (p = 0.004), increasing to 100 % at 1-year follow-up (p < 0.001). Normoglycemic patients and patients with borderline OGTT experienced mild or severe hypoglycemia during the glucose tolerance test at 3, 6, and 12 months' follow-up.

CONCLUSIONS

LSG offers excellent results to morbidly obese patients with regard to type 2 diabetes mellitus. Implementation of OGTT in these patients can be a valuable tool in their postoperative management. Bariatric teams performing LSG for morbid obesity should heighten their sensitivity to postoperative hypoglycemia, even in patients with type 2 diabetes mellitus.

Improvements in hippocampal-dependent memory and microglial infiltration with calorie restriction and gastric bypass surgery, but not with vertical sleeve gastrectomy

BACKGROUND

Much recent evidence suggest that obesity and related comorbidities contribute to cognitive decline, including the development of non age-related dementia and Alzheimer's disease. Obesity is a serious threat to public health, and few treatments offer proven long-term weight loss. In fact, bariatric surgery remains the most effective long-term therapy to reduce weight and alleviate other aspects of the metabolic syndrome (MetS). Unlike the demonstrated benefits of caloric restriction to prevent weight gain, few if any studies have compared various means of weight loss on central nervous system function and hippocampal-dependent cognitive processes.

DESIGN AND RESULTS

Our studies comprise the first direct comparisons of caloric restriction to two bariatric surgeries (Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG)) on cognitive function. Weight loss following caloric restriction, RYGB and VSG was associated with generalized improvements in metabolic health and hippocampal-dependent learning, as measured in the radial arm maze and spontaneous alternation tests. However, VSG-treated rats exhibited deficits on spatial learning tasks in the Morris water maze. In addition, whereas VSG animals had elevated hippocampal inflammation, comparable to that of obese controls, RYGB and calorie-restricted (pair-fed, PF) controls exhibited an amelioration of inflammation, as measured by the microglial protein ionized calcium binding adaptor molecule 1 (IBA1). We also assessed whether GHR (ghrelin) replacement would attenuate hippocampal inflammation in VSG, as post-surgical GHR levels are significantly reduced in VSG relative to RYGB and PF rats. However, GHR treatment did not attenuate the hippocampal inflammation.

CONCLUSION

Although VSG was comparably effective at reducing body weight and improving glucose regulation as RYGB, VSG did not appear to confer an equal benefit on cognitive function and markers of inflammation.