Surgical treatment of type 2 diabetes in subjects with mild obesity: mechanisms underlying metabolic improvements

Enteroendocrine Reprogramming by Altered Epithelial-Mesenchymal Crosstalk in Metabolic Surgery

Metabolic surgery is an effective treatment option for type 2 diabetes. However, the therapeutic scope has been limited by unexpected inconsistent outcomes. This study aims to overcome these obstacles by determining fundamental mechanisms from a novel perspective by analyzing and comparing the surgical anatomy, clinical characteristics, and outcomes of metabolic surgery, including duodenal-jejunal bypass, Roux-en-Y gastric bypass, biliopancreatic diversion, one anastomosis gastric bypass, and their modified procedures, predominantly focusing on nonobese patients to mitigate confounding effects from overweighted type 2 diabetes. Regional epithelial cell growth and unique villus formation along the anterior-posterior axis of the small intestine depend on crosstalk between the epithelium and the underlying mesenchyme. Due to altered crosstalk between the epithelium and the opposite mesenchyme at the anastomotic site, the enteroendocrine lineage of the distal intestine is replaced by the proximal epithelium after the bypass procedure. Subsequent intestinal compensatory proliferation accelerates the expansion of the replaced epithelium, including enteroendocrine cells. The primary reasons for unsatisfactory results are incomplete duodenal exclusion and insufficient biliopancreatic limb length. We anticipate that this novel mechanism will have a significant impact on metabolic surgery outcomes and provide valuable insight into optimizing its effectiveness in type 2 diabetes.

Change in Adipokines and Gastrointestinal Hormones After Bariatric Surgery: a Meta-analysis

PURPOSE

The study aimed to perform a meta-analysis about the change in adipokines and gastrointestinal hormones after bariatric surgery in patients with obesity.

MATERIALS AND METHODS

We searched the Cochrane Central Register of Controlled Trials, EMBASE, and PubMed for related articles and used Review Manager 5.4 for data aggregation. Sensitivity and subgroup analysis were also conducted when feasible.

RESULTS

As a result, 95 articles involving 6232 patients were included in the meta-analysis. After bariatric surgery, the levels of leptin, ghrelin, C-reactive protein (CRP), interleukin-6 (IL-6), high-sensitivity C-reactive protein (Hs-CRP), tumor necrosis, factor-α (TNF-α), and interleukin-1β (IL-1β) reduced, while adiponectin, glucagon-like peptide-1 (GLP-1), and peptide YY (PYY) levels increased significantly. Subgroup analysis indicated that there was a more significant reduction in leptin level with a longer follow-up time. OAGB had a greater effect on increasing adiponectin level compared with other procedures. SG procedure would bring about reduced ghrelin, while BPD resulted in increased ghrelin. Meta-regression analysis found that publication year, study design, number of patients, preoperative age, preoperative BMI, and quality assessment score were not significantly related to change in leptin, adiponectin, and ghrelin levels.

CONCLUSION

Bariatric surgery was associated with a significant decrease in leptin, ghrelin, CRP, IL-6, Hs-CRP, TNF-α, and IL-1β, as well as increase in adiponectin, GLP-1, and PYY levels.

The Role of Beta Cell Recovery in Type 2 Diabetes Remission

Type 2 diabetes (T2D) has been considered a relentlessly worsening disease, due to the progressive deterioration of the pancreatic beta cell functional mass. Recent evidence indicates, however, that remission of T2D may occur in variable proportions of patients after specific treatments that are associated with recovery of beta cell function. Here we review the available information on the recovery of beta cells in (a) non-diabetic individuals previously exposed to metabolic stress; (b) T2D patients following low-calorie diets, pharmacological therapies or bariatric surgery; (c) human islets isolated from non-diabetic organ donors that recover from “lipo-glucotoxic” conditions; and (d) human islets isolated from T2D organ donors and exposed to specific treatments. The improvement of insulin secretion reported by these studies and the associated molecular traits unveil the possibility to promote T2D remission by directly targeting pancreatic beta cells.

Effectiveness and Safety of Laparoscopic Sleeve Gastrectomy for Weight Loss in Mild Obesity: Prospective Cohort Study with 3-Year Follow-up

PURPOSE

Patients with mild obesity especially in absence of associated medical problems (OAMP) are commonly managed by non-surgical approaches. Laparoscopic sleeve gastrectomy (LSG) has proved itself to be effective and it is now the most performed weight loss procedure. We aimed to study the effectiveness and safety of LSG for weight loss in mild obesity.

METHODS

A prospective cohort study. Group A; BMI (30-34.9 kg/m²), and group B; BMI ≥ 40 or BMI ≥ 35 with OAMP. Demographic data, perioperative complications, % excess weight loss (EWL), % total weight loss (TWL), nutritional profile, and evolution of OAMP were recorded and statistically analyzed.

RESULTS

A total of 250 patients, with 80 patients (32%) in group A, and 170 (68%) in group B. The majority were female. The mean preoperative weight, BMI, and excess weight were 90.1 ± 9.52, 32.7 ± 1.4, and 21.5 ± 4.9 in group A, and 129.88 ± 26.12, 47.8 ± 8.2, and 62.3 ± 23.6 kg in group B respectively. The low BMI group had significantly lower OAMP, with higher pre-LSG non-surgical procedures rate. Overall post-operative morbidity rate was significantly higher in group B. %TWL was significantly lower in low BMI group. Nutritional profile was within the normal range in both groups at 3-year follow-up.

CONCLUSION

Laparoscopic sleeve gastrectomy is a safe and effective weight loss solution for mild obesity with better outcome than for higher BMI. Further studies are warranted to reconsider NIH's statement for medicolegal aspects, and for matching the current changes in bariatric surgery practice, safety evidence, and patients' demand.

Determinants of type 2 diabetes remission after bariatric surgery in obese Japanese patients: a retrospective cohort study

Objective

Bariatric surgery (BS) improves glycemic control in type 2 diabetes; however, some patients show insufficient improvement. Understanding the pathophysiology of type 2 diabetes in obese patients can facilitate appropriate treatment for type 2 diabetes after BS. The homeostatic model assessment (HOMA) 2 enables the calculation of the values from C-peptide data and evaluation of insulin users. We aimed to evaluate the pathophysiology of type 2 diabetes using pre- and postoperative parameters and HOMA2 in obese patients who underwent BS.

Methods

We retrospectively reviewed data from 45 obese patients with type 2 diabetes who underwent BS. They were followed-up for 12 months. The relationship between the HOMA2 score and complete remission (CR) of type 2 diabetes after BS was analyzed. Patients with and without CR were assigned to the CR and non-CR groups, respectively. Multiple regression analysis was used to identify factors associated with improvement in type 2 diabetes after BS.

Results

BS significantly improved body weight and glucose metabolism. The preoperative glycosylated hemoglobin A1c level and insulin secretion (HOMA2-%B) significantly differed between the CR and non-CR groups. Postoperative weight reduction and improved insulin sensitivity correlated significantly with CR; multiple regression showed that the preoperative HOMA 2-%B independently predicted CR of type 2 diabetes after BS.

Conclusion

Preoperative insulin secretion, improvement in insulin sensitivity, and weight reduction after BS are related to CR of type 2 diabetes after BS. The results better reveal the pathophysiology of and treatment for type 2 diabetes in obese patients who undergo BS.

Does Roux-en-Y Construction Really Bring Benefit of Type 2 Diabetes Mellitus Remission After Gastrectomy in Patients with Gastric Cancer? A Systematic Review and Meta-Analysis

INTRODUCTION

To evaluate whether the extent of gastrectomy or the reconstruction method brings benefit of type 2 diabetes mellitus (T2DM) remission after gastrectomy in patients with gastric cancer.

METHODS

PUBMED, EMBASE, the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library were searched to find eligible studies published from inception to July 31, 2020.

RESULTS

A total of nine studies (1424 patients) were included. At the first year and the end of follow-up time after gastrectomy, the total gastrectomy group had better T2DM remission than the subtotal gastrectomy group, and the Roux-en-Y reconstruction (R-Y) group had better T2DM remission compared with the non-R-Y group. There was no difference between R-Y and non-R-Y in terms of subtotal gastrectomy (OR 1.08, 95% CI 0.63-1.84, P = 0.78). However, total gastrectomy with R-Y had better T2DM remission than subtotal gastrectomy with R-Y (OR 2.75, 95% CI 1.19-6.35, P = 0.02).

CONCLUSION

Total gastrectomy with R-Y had better T2DM remission. The extent of gastrectomy rather than the reconstruction method might play an important role in T2DM remission after gastrectomy in patients with gastric cancer.

Metabolic Outcomes of Surgery for Non-Obese Type 2 Diabetes

The most plausible contributing factor to non-obese type 2 diabetes may be imbalanced incretin release from the intestinal epithelium in response to nutrients. Rerouting intestinal continuity through bypass surgery to modulate incretin release is therefore a reasonable treatment. We believe that a major determinant of metabolic outcomes is entire duodenal exclusion without leaving any duodenal epithelium and exclusion of sufficient length of jejunum. More importantly, the procedure should be implemented with safety and without sequelae. To achieve this, we invented a novel procedure with acceptable surgical safety and excellent and durable metabolic outcomes. Post-surgical intestinal adaptation should be considered to achieve successful outcomes.

Physiologic Mechanisms of Type II Diabetes Mellitus Remission Following Bariatric Surgery: a Meta-analysis and Clinical Implications

INTRODUCTION

As obesity prevalence grows in the USA, metabolic syndrome is becoming increasingly more common. Current theories propose that insulin resistance is responsible for the hypertension, dyslipidemia, type II diabetes mellitus (T2DM), and low HDL that comprise metabolic syndrome. Bariatric surgery is one potential treatment, and its effects include permanently altering the patient's physiology and glucose regulation. Consequently, patients with T2DM who undergo bariatric surgery often experience tighter glucose control or remission of their T2DM altogether. This meta-analysis aims to explore the physiologic mechanisms underlying T2DM remission following bariatric surgery, which demonstrates effects that could lead to expansion of the NIH criteria for bariatric surgery candidates.

METHODS

A comprehensive search was conducted in PubMed and Scopus. Two independent reviewers conducted title, abstract, and full text review of papers that met inclusion criteria. Papers that measured hormone levels before and after bariatric surgery were included in the meta-analysis. Weighted means and standard deviations were calculated for preoperative and postoperative GLP-1, GIP, ghrelin, and glucagon.

RESULTS

Total postprandial GLP-1 increased following bariatric surgery, which correlated with improvements in measures of glycemic control. Fasting GLP-1, fasting GIP, total postprandial GIP, total fasting ghrelin, and fasting glucagon all decreased, but all changes in hormones evaluated failed to reach statistical significance. Studies also demonstrated changes in hepatic and peripancreatic fat, inflammatory markers, miRNA, and gut microbiota following bariatric surgery.

CONCLUSION

While this meta-analysis sheds light on possible mechanisms, further studies are necessary to determine the dominant mechanism underlying remission of T2DM following bariatric surgery.

The Effects of Bariatric Surgery on Islet Function, Insulin Secretion, and Glucose Control

Although bariatric surgery was developed primarily to treat morbid obesity, evidence from the earliest clinical observations to the most recent clinical trials consistently demonstrates that these procedures have substantial effects on glucose metabolism. A large base of research indicates that bariatric surgeries such as Roux-en-Y gastric bypass (RYGB), vertical sleeve gastrectomy (VSG), and biliopancreatic diversion (BPD) improve diabetes in most patients, with effects frequently evident prior to substantial weight reduction. There is now unequivocal evidence from randomized controlled trials that the efficacy of surgery is superior to intensive life-style/medical management. Despite advances in the clinical understanding and application of bariatric surgery, there remains only limited knowledge of the mechanisms by which these procedures confer such large changes to metabolic physiology. The improvement of insulin sensitivity that occurs with weight loss (e.g., the result of diet, illness, physical training) also accompanies bariatric surgery. However, there is evidence to support specific effects of surgery on insulin clearance, hepatic glucose production, and islet function. Understanding the mechanisms by which surgery affects these parameters of glucose regulation has the potential to identify new targets for therapeutic discovery. Studies to distinguish among bariatric surgeries on key parameters of glucose metabolism are limited but would be of considerable value to assist clinicians in selecting specific procedures and investigators in delineating the resulting physiology. This review is based on literature related to factors governing glucose metabolism and insulin secretion after the commonly used RYGB and VSG, and the less frequently used BPD and adjustable gastric banding.

A Meta-Analysis of GLP-1 After Roux-En-Y Gastric Bypass: Impact of Surgical Technique and Measurement Strategy

BACKGROUND

Roux-en-Y gastric bypass (RYGB) is an effective treatment for diabetes. Glucagon-like peptide-1 (GLP-1) is a gut hormone that is important to glucose homeostasis.

OBJECTIVE

This study aimed to assess GLP-1 level and its predictors after RYGB.

METHODS

The study design was a meta-analysis. The data sources were MEDLINE, EMBASE, Web of Science, and the Cochrane Databases. The study selection composed of studies with pre- and post-RYGB levels. The main outcomes were as follows: Primary outcome was the change in postprandial GLP-1 levels after RYGB. Secondary outcomes included the changes in fasting glucose, fasting insulin, and fasting GLP-1 levels after RYGB. Meta-regression to determine predictors of changes in GLP-1 levels was performed. Outcomes were reported using Hedge's g.

RESULTS

Twenty-four studies with 368 patients were included. Postprandial GLP-1 levels increased after RYGB (Hedge's g = 1.29, p < 0.0001), while fasting GLP-1 did not change (p = 0.23). Peak postprandial GLP-1 levels gave the most consistent results (I ² = 9.11). Fasting glucose and insulin levels decreased after RYGB (p < 0.0001). Roux limb length was a significant predictor for amount of GLP-1 increase (β = - 0.01, p = 0.02). Diabetes status, amount of weight loss, length of biliopancreatic limb, and time of measurement were not significant predictors (p > 0.05).

CONCLUSION

Postprandial GLP-1 levels increase after RYGB, while fasting levels remain unchanged. Shorter Roux limb length is associated with greater increase in postprandial GLP-1, which may lead to better glycemic control in this population.

DIABETES REMISSION RATE IN DIFFERENT BMI GRADES FOLLOWING ROUX-EN-Y GASTRIC BYPASS

Background:

Type 2 diabetes mellitus has a high long-term remission rate after laparoscopic Roux-en-Y gastric bypass (LRYGB), but few studies have analyzed patients with BMI<35 kg/m².

Aim:

To compare glycemic control after LRYGB between BMI 30-35 kg/m² (intervention group or IG) and >35 kg/m² patients (control group or CG) and to evaluate weight loss, comorbidities and surgical morbidity.

Methods:

Sixty-six diabetic patients (30 in IG group and 36 in CG group) were submitted to LRYGB. Data collected annually after surgery were analyzed with generalized estimating equations.

Results:

Average follow-up was 4.3 years. There was no statistical difference between groups using complete remission American Diabetes Association criteria (OR 2.214, 95%CI 0.800-5.637, p=0.13). There was significant difference between groups using partial remission American Diabetes Association criteria (p=0.002), favouring the CG group (OR 6.392, 95%CI 1.922-21.260). The higher BMI group also had lower HbA1c levels (-0.77%, 95%CI -1.26 to -0.29, p=0.002). There were no significant differences in remission of hypertension, dyslipidemia and surgical morbidity, while weight was better controlled in the IG group.

Conclusion:

No differences were found in diabetes complete remission, although greater partial remission and the lower levels of glycated hemoglobin in the BMI >35 kg/m² group suggest a better response among more obese diabetic patients with LRYGB. In addition, both groups had important metabolic modifications at the expense of low morbidity.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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