Bariatric surgery: prevalence, predictors, and mechanisms of diabetes remission

Cardiovascular Effects of Weight Loss in Obese Patients with Diabetes: Is Bariatric Surgery the Additional Arrow in the Quiver?

Obesity is an increasingly widespread disease worldwide because of lifestyle changes. It is associated with an increased risk of cardiovascular disease, primarily type 2 diabetes mellitus, with an increase in major cardiovascular adverse events. Bariatric surgery has been shown to be able to reduce the incidence of obesity-related cardiovascular disease and thus overall mortality. This result has been shown to be the result of hormonal and metabolic effects induced by post-surgical anatomical changes, with important effects on multiple hormonal and molecular axes that make this treatment more effective than conservative therapy in determining a marked improvement in the patient's cardiovascular risk profile. This review, therefore, aimed to examine the surgical techniques currently available and how these might be responsible not only for weight loss but also for metabolic improvement and cardiovascular benefits in patients undergoing such procedures.

The gut signals to AGRP-expressing cells of the pituitary to control glucose homeostasis

Glucose homeostasis can be improved after bariatric surgery, which alters bile flow and stimulates gut hormone secretion, particularly FGF15/19. FGFR1 expression in AGRP-expressing cells is required for bile acids' ability to improve glucose control. We show that the mouse Agrp gene has 3 promoter/enhancer regions that direct transcription of each of their own AGRP transcripts. One of these Agrp promoters/enhancers, Agrp-B, is regulated by bile acids. We generated an Agrp-B knockin FLP/knockout allele. AGRP-B-expressing cells are found in endocrine cells of the pars tuberalis and coexpress diacylglycerol lipase B - an endocannabinoid biosynthetic enzyme - distinct from pars tuberalis thyrotropes. AGRP-B expression is also found in the folliculostellate cells of the pituitary's anterior lobe. Mice without AGRP-B were protected from glucose intolerance induced by high-fat feeding but not from excess weight gain. Chemogenetic inhibition of AGRP-B cells improved glucose tolerance by enhancing glucose-stimulated insulin secretion. Inhibition of the AGRP-B cells also caused weight loss. The improved glucose tolerance and reduced body weight persisted up to 6 weeks after cessation of the DREADD-mediated inhibition, suggesting the presence of a biological switch for glucose homeostasis that is regulated by long-term stability of food availability.

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.

Early continuous glucose monitoring for predicting remission of type 2 diabetes 1 year after bariatric surgery

BACKGROUND

Bariatric surgery in obese subjects can result in remission of type 2 diabetes (T2D) at a distant time post-surgery. The aim of our observational prospective single-centre study was to examine glycaemic patterns in adult T2D candidates for bariatric surgery using a continuous glucose monitoring (CGM) sensor for 14 days after surgery to search for indicators predictive of T2D remission 1 year later.

METHODS

Patients underwent CGM preoperatively and for 14 days postoperatively. Thereafter, body weight and glycated haemoglobin (HbA1c) levels were monitored at 3, 6 and 12 months after surgery.

RESULTS

A total of 31 patients (mean age 47±2 years) were analyzed. After surgery, mean interstitial glucose levels fell rapidly from 157±31mg/dL preoperatively to 109±35mg/dL postoperatively (P<0.001), reaching nadir levels from day 3 after surgery. Successful bariatric surgery (loss of excess weight ≥50%) was observed in 28 (90%) patients, and diabetes remission (HbA1c≤6% with no antidiabetic treatment) 1 year after surgery was noted in 21 (68%) patients. CGM for 14 days post-surgery allowed prediction of diabetes remission 1 year after surgery: time spent above range <14% and standard deviation (SD) of glucose levels <33mg/dL were both strong predictors of T2D remission. Indeed, the association of these two criteria predicted diabetes remission with a 100% positive predictive value, 81% sensitivity and 100% specificity and, when combined with the advanced Diabetes Remission (Ad-DiaRem) score, further increased predictive accuracy.

CONCLUSION

The use of 14-day postoperative CGM recordings together with presurgical clinical scores can help to predict diabetes remission 1 year after bariatric surgery.

Serum Levels and Adipose Tissue Gene Expression of Cathelicidin Antimicrobial Peptide (CAMP) in Obesity and During Weight Loss

CAMP (Cathelicidin antimicrobial peptide) is synthesized and secreted by adipocytes and involved in adipose tissue (AT) innate immune response and host defense of subcutaneous AT against Gram positive bacteria. Data on the regulation of CAMP in obesity and during weight loss are scarce and reference values do not exist. Serum CAMP levels (ELISA) and AT gene expression levels (quantitative real time PCR) were investigated in two large and longitudinal (12 months) cohorts of severely obese patients undergoing either a low calorie diet (LCD; n=79) or bariatric surgery (BS; n=156). The impact of metabolic factors on CAMP expression in vitro was investigated in differentiated 3T3-L1 adipocytes. CAMP serum levels significantly increased after BS but not during LCD. Females had lower CAMP serum levels and lower gene expression levels in subcutaneous AT. CAMP was positively correlated to unfavorable metabolic factors/adipokines and negatively to favorable factors/adipokines. CAMP gene expression was higher in subcutaneous than in visceral AT but serum CAMP levels were not correlated to levels of AT gene expression. While certain bile acids upregulated CAMP expression in vitro, high glucose/insulin as well as GLP-1 had an inhibitory effect. There exist gender-specific and AT compartment-specific effects on the regulation of CAMP gene expression. Weight loss induced by BS (but not by LCD) upregulated CAMP serum levels suggesting the involvement of weight loss-independent mechanisms in CAMP regulation such as bile acids, incretins and metabolic factors. CAMP might represent an adipokine at the interface between metabolism and innate immune response.

Ultra-Early and Early Changes in Bile Acids and Insulin After Sleeve Gastrectomy Among Obese Patients

BACKGROUND AND OBJECTIVE

In obese patients, sleeve gastrectomy (SG) has shown mixed results on bile acid (BA) values. The aim of our study was to examine the potential ultra-early and early changes of the circulating total BA in relation with the changes of insulin resistance (IR) in obese patients submitted to laparoscopic SG. Materials and Methods: Twenty-four obese subjects were investigated for body mass index (BMI), total fasting BA, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), and leptin before and at 7 and 30 d after SG. Results: After surgery, mean BMI decreased at the first (p < 0.001) and at the second time point (p < 0.001) relative to baseline. Total fasting BA values did not change significantly at 7 d (p = 0.938) and at 30 d (p = 0.289) after SG. No significant changes were found at 7 d (p = 0.194, p = 0.34) and 30 d (p = 0.329, p = 0.151) after surgery regarding fasting insulin and HOMA-IR, respectively. However, a trend of increased total fasting BA and decreased fasting insulin and HOMA- after laparoscopic SG has been found. Negative correlations between total fasting BA and insulin (r = -0.807, p = 0.009), HOMA-IR (r = -0.855, p = 0.014), and blood glucose (r = -0.761, p = 0.047), respectively, were observed at one month after SG. Conclusion: In conclusion, here, we found a lack of significant changes in total fasting BA, insulin, and HOMA-IR ultra-early and early after SG, which precluded us to consider a possible relation between the variations of BA and IR. However, the presence of the tendency for total fasting BA to increase and for insulin and HOMA-IR to decrease, as well as of the negative correlations one month after laparoscopic SG, suggest that this surgery brings about some changes that point towards the existence, and possibly towards the restoration, at least to some extent, of the link between BA and glucose metabolism.

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

BACKGROUND

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

OBJECTIVES

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

SETTING

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The histomorphometric parameters of endocrine pancreas after bariatric surgery in healthy animal models

BACKGROUND

The aim of this study is to describe in depth how different bariatric surgeries affect to the cellularity of β-cells in the pancreatic islet. There are much data regarding the possible physiological mechanisms involved in resolution of type 2 diabetes after bariatric surgery. But these data usually are controversial. We reported a direct influence of bariatric surgical technique on endocrine pancreas cellular turnover. Some surgeries increase proliferation processes of the β-cells. Our objective is to report the histomorphometric mechanism that these techniques stimulate over the cellularity of pancreatic islet.

METHOD

To this purpose, we used adult male Wistar rats to undergo the different techniques. We developed three surgical techniques (Sleeve gastrectomy and Y-Roux Gastric bypass as the most usual bariatric techniques, and a purely malabsorptive technique); moreover two control groups were performed (Sham and fasting controls).

RESULTS

We completed a sequence of morphometric studies to conclude the behaviour of endocrine pancreatic β-cell islet, correlating several histomorphometry parameters.

CONCLUSION

Our purpose was to show a comprehensive interpretation to the consequences that bariatric surgeries had on the pancreatic islets cellularity. Moreover, we included the main tests to report the cellularity in histological samples.

Metabolic (Bariatric and Nonbariatric) Surgery for Type 2 Diabetes: A Personal Perspective Review

: Metabolic surgery can cause amelioration, resolution, and possible cure of type 2 diabetes. Bariatric surgery is metabolic surgery. In the future, there will be metabolic surgery operations to treat type 2 diabetes that are not focused on weight loss. These procedures will rely on neurohormonal modulation related to the gut as well as outside the peritoneal cavity. Metabolic procedures are and will always be in flux as surgeons seek the safest and most effective operative modality; there is no enduring gold standard operation. Metabolic bariatric surgery for type 2 diabetes is more than part of the clinical armamentarium, it is an invitation to perform basic research and to achieve fundamental scientific knowledge.

Improved glucose metabolism following bariatric surgery is associated with increased circulating bile acid concentrations and remodeling of the gut microbiome

Clinical studies have indicated that circulating bile acid (BA) concentrations increase following bariatric surgery, especially following malabsorptive procedures such as Roux-en-Y gastric bypasses (RYGB). Moreover, total circulating BA concentrations in patients following RYGB are positively correlated with serum glucagon-like peptide-1 concentrations and inversely correlated with postprandial glucose concentrations. Overall, these data suggest that the increased circulating BA concentrations following bariatric surgery - independently of calorie restriction and body-weight loss - could contribute, at least in part, to improvements in insulin sensitivity, incretin hormone secretion, and postprandial glycemia, leading to the remission of type-2 diabetes (T2DM). In humans, the primary and secondary BA pool size is dependent on the rate of biosynthesis and the enterohepatic circulation of BAs, as well as on the gut microbiota, which play a crucial role in BA biotransformation. Moreover, BAs and gut microbiota are closely integrated and affect each other. Thus, the alterations in bile flow that result from anatomical changes caused by bariatric surgery and changes in gut microbiome may influence circulating BA concentrations and could subsequently contribute to T2DM remission following RYGB. Research data coming largely from animal and cell culture models suggest that BAs can contribute, via nuclear farnezoid X receptor (FXR) and membrane G-protein-receptor (TGR-5), to beneficial effects on glucose metabolism. It is therefore likely that FXR, TGR-5, and BAs play a similar role in glucose metabolism following bariatric surgery in humans. The objective of this review is to discuss in detail the results of published studies that show how bariatric surgery affects glucose metabolism and subsequently T2DM remission.

Type 2 diabetes remission following gastric bypass: does diarem stand the test of time?

OBJECTIVE(S)

Roux-en-Y Gastric Bypass (RYGB) is well known to ameliorate type 2 diabetes mellitus (T2DM), and recent work suggests that the preoperative DiaREM model predicts successful remission up to 1 year post-RYGB. However, no data exist for long-term validity. Therefore, we sought to determine the utility of this score on long-term RYGB effectiveness for T2DM resolution at 2 and 10 years, respectively.

METHODS

T2DM patients (Age: 48, BMI: 49, HbA_1C: 8.1) undergoing RYGB at the University of Virginia between 2004-2006 (n = 42) and 2012-2014 (n = 59) were evaluated prospectively to assess preoperative DiaREM score, defined from insulin use, age, HbA_1C, and type of antidiabetic medication. T2DM partial remission status was based on the American Diabetes Association guidelines (HbA_1C < 6.5 % and fasting glycemia <125 mg/dL, and no anti-diabetic medications). Chi-square test was used to compare patient's T2DM status to their DiaREM probability of remission.

RESULTS

Among RYGB patients with 2-year postoperative data, 2 were lost (n = 1 no follow-up and n = 1 died) resulting in 57 patients for analysis. For the 10-year postoperative data, 11 were lost (n = 6 no follow-up and n = 5 died), thereby resulting in only 31 patients for analysis. Patients were distributed by DiaREM score to correlate with the predicted probability of remission as follows: 0-2 (Predicted 94 %, 2-year 100 % p = 0.61, 10-year 100 % p = 0.72), 3-7 (Predicted 76 %, 2-year 94 % p = 0.08, 10-year 83 % p = 0.57), 8-12 (Predicted 36 %, 2-year 47 % p = 0.38, 10-year 43 % p = 0.72), 13-17 (Predicted 22 %, 2-year 20 % p = 0.92, 10-year 33 % p = 0.64), and 18-22 (Predicted 9 %, 2-year 15 % p = 0.40, 10-year 14 % p = 0.64).

CONCLUSIONS

Preoperative DiaREM scores are a good tool for predicting both short- and long-term T2DM remissions following RYGB. This study highlights the need to identify strategies that improve T2DM remission in those at highest risk.

Perioperative Glycemic Management of Patients Undergoing Bariatric Surgery

Bariatric surgery in patients with type 2 diabetes has been shown to improve glycemic control and reduce need for glucose-lowering medications. Some of these improvements occur in the early postoperative period prior to any weight loss. These early reductions in circulating glucose can be attributed to primarily perioperative caloric restriction and prolonged fasting. Inpatient glycemic targets for patients undergoing bariatric surgery are similar to those recommended for other surgical procedures as a way of minimizing risk for complications. There is evidence that achieving perioperative and postoperative glycemic targets can improve the ability to achieve remission of type 2 diabetes following gastric bypass surgery. This review provides recommendations regarding glycemic goals, strategies for achieving these goals with minimal risk for hypoglycemia, and an examination of the data suggesting an association between perioperative glycemic management and diabetes remission following bariatric surgery.

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.

Metabolic Mechanisms in Obesity and Type 2 Diabetes: Insights from Bariatric/Metabolic Surgery

Obesity and the related diabetes epidemics represent a real concern worldwide. Bariatric/metabolic surgery emerged in last years as a valuable therapeutic option for obesity and related diseases, including type 2 diabetes mellitus (T2DM). The complicated network of mechanisms involved in obesity and T2DM have not completely defined yet. There is still a debate on which would be the first metabolic defect leading to metabolic deterioration: insulin resistance or hyperinsulinemia? Insight into the metabolic effects of bariatric/metabolic surgery has revealed that, beyond weight loss and food restriction, other mechanisms can be activated by the rearrangements of the gastrointestinal tract, such as the incretinic/anti-incretinic system, changes in bile acid composition and flow, and modifications of gut microbiota; all of them possibly involved in the remission of T2DM. The complete elucidation of these mechanisms will lead to a better understanding of the pathogenesis of this disease. Our aim was to review some of the metabolic mechanisms involved in the development of T2DM in obese patients as well as in the remission of this condition in patients submitted to bariatric/metabolic surgery.