Early Metabolic Improvement After Bariatric Surgery: The First Steps Toward Remission of Type 2 Diabetes

Metabolic disorders induced the changes in the expressions of TNFα, E-cadherin and ultrastructural alteration of liver cells in a typical animal model of type 2 diabetes: Psammomys obesus

By using a unique animal model of type 2 diabetes mellitus, Psammomys obesus induced by a high-calorie diet (HCD) for nine months, we showed for the first time, in the liver, the impact of inflammation on the remodeling of intercellular junction molecules E-cadherins during the progression of steatohepatitis. Under the effect of HCD, the expressions of immunohistochemical markers, Tumor Necrosis Factor alpha (TNFα) and E-cadherins were inversely correlated. Ultrastructural examination revealed the involvement of destabilization and loss of E-cadherins in the process of hepatic pathogenesis. This mechanical maintenance stress was favored by the recruitment of immune cells which contributed to the triggering and progression of fibrosis by the enlargement of the intercellular space and the invasion of collagen fibers. Furthermore to escape cell death, loss of E-cadherins played a major role in mediating fibrosis. Psammomys obesus is a promising model for experimental research, enabling the extrapolation of observed structural and functional alterations in humans, the objective to find new therapeutic targets. The physiological resemblance between Psammomys obesus and humans enhances the precision and relevance of biomedical research efforts.

Contemporary Clinical Perspectives on Targeting Remission of Type 2 Diabetes

It has long been known that some patients with type 2 diabetes (T2DM) can experience sustained metabolic improvement to near-normal levels of glycemia either spontaneously or after medical intervention. Now recognized as remission of diabetes, this intriguing state is currently more feasible than ever before due to profound advances in metabolic surgery, pharmacologic therapy, and regimens of lifestyle modification. This enhanced capacity to induce remission has revealed new pathophysiologic insights, including the presence of a reversible component of the pancreatic beta-cell dysfunction that otherwise drives the chronic progressive nature of T2DM. In doing so, it has changed the therapeutic landscape by offering new potential management objectives and considerations for patients and providers. However, the excitement around these developments must also be tempered by the sobering realities of our current understanding of remission, including the recognition that this condition may not be permanent (resulting in glycemic relapse over time) and that beta-cell function may not be normalized in the setting of remission. These limitations highlight both the many gaps in our current understanding of remission and the caution with which clinical discussions must be handled for clear patient-directed communication of the pros and cons of targeting this outcome in practice. In this mini-review, we consider this rapidly growing literature, including its implications and its limitations, and thereby seek to provide objective balanced perspectives on targeting remission of T2DM in current clinical care.

Baseline determinants of remission of type 2 diabetes in response to short-term insulin-based therapy: The pivotal role of beta-cell function

AIM

To identify baseline determinants of diabetes remission in response to short-term insulin-based therapy.

METHODS

In this study, adult patients with type 2 diabetes (T2D) of less than 7 years duration were randomized to 8 weeks of treatment with (a) insulin glargine, (b) glargine + thrice-daily lispro, or (c) glargine + twice-daily exenatide, followed by 12 weeks of washout that enabled assessment of remission (defined as HbA1c < 6.5% after ≥ 3 months without glucose-lowering therapy). At baseline, 8 weeks and washout, beta-cell function was assessed with four measures: Insulin Secretion-Sensitivity Index-2 (ISSI-2), insulinogenic index/Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), ΔC-peptide_0-120 /Δglucose_0-120  × Matsuda and Δinsulin secretion rate (ISR)_0-120 /Δgluc_0-120  × Matsuda.

RESULTS

Diabetes remission was achieved in 31 of 90 participants (34.4%). Compared with their peers, those who went on to remission had lower HbA1c (P < .001) and better beta-cell function at baseline (all four measures P ≤ .01). The non-remission and remission groups did not otherwise differ in baseline insulin sensitivity/resistance (Matsuda, HOMA-IR), body mass index, duration of diabetes, pretrial diabetes medications or allocated insulin-based therapy during the trial. On logistic regression analyses, each baseline measure of beta-cell function emerged as a significant predictor of remission (log ISSI-2: adjusted OR 4.41 [95% CI: 1.71-11.34]; log insulinogenic index/HOMA-IR: 2.21 [1.26-3.89]; log ΔC-peptide_0-120 /Δglucose_0-120  × Matsuda: 1.62 [1.00-2.64]; log ΔISR_0-120 /Δgluc_0-120  × Matsuda: 1.87 [1.09-3.23]). Similarly, higher baseline ISSI-2 tertile predicted longer time to glycaemic relapse after cessation of the insulin-based therapy (log-rank P = .029).

CONCLUSION

Beta-cell function is the dominant baseline pathophysiological determinant of the likelihood of achieving remission of diabetes in response to short-term insulin-based therapy.

Novel Insight into the Mechanism of Metabolic Surgery Causing the Diversity in Glycemic Status in Type 2 Diabetes

Metabolic surgery results in diverse glycemic status in patients with type 2 diabetes (T2D), including hyperglycemia without remission, significant amelioration of hyperglycemia with partial remission, complete restoration of euglycemia, or with prolonged remission, hyperglycemia recurrence in relapses after remission, or post-bariatric hypoglycemia. Unfortunately, it is not known how metabolic surgery leads to this diverse consequence. Here, we discuss the diversity of glycemic status associated with metabolic surgery and the potential mechanisms of T2D remission. We also highlight the relationship between the change in low-grade inflammation and T2D remission after metabolic surgery. We hypothesize that the level of inflammatory and anti-inflammatory cytokines controls the efficacy of metabolic surgery in patients with T2D. This hypothesis may provide further insight into the mechanism of the beneficial effects of metabolic surgery patients with T2D.

Remission of Diabetes Following Bariatric Surgery: Plasma Proteomic Profiles

Bariatric surgery restores glucose tolerance in many, but not all, severely obese subjects with type 2 diabetes (T2D). We aimed to evaluate the plasma protein profiles associated with the T2D remission after obesity surgery. We recruited seventeen women with severe obesity submitted to bariatric procedures, including six non-diabetic patients and eleven patients with T2D. After surgery, diabetes remitted in 7 of the 11 patients with T2D. Plasma protein profiles at baseline and 6 months after bariatric surgery were analyzed by two-dimensional differential gel electrophoresis (2D-DIGE) and matrix-assisted laser desorption/ionization-time-of-flight/time-of-flight coupled to mass spectrometry (MALDI-TOF/TOF MS). Remission of T2D following bariatric procedures was associated with changes in alpha-1-antichymotrypsin (SERPINA 3, p < 0.05), alpha-2-macroglobulin (A2M, p < 0.005), ceruloplasmin (CP, p < 0.05), fibrinogen beta chain (FBG, p < 0.05), fibrinogen gamma chain (FGG, p < 0.05), gelsolin (GSN, p < 0.05), prothrombin (F2, p < 0.05), and serum amyloid p-component (APCS, p < 0.05). The resolution of diabetes after bariatric surgery is associated with specific changes in the plasma proteomic profiles of proteins involved in acute-phase response, fibrinolysis, platelet degranulation, and blood coagulation, providing a pathophysiological basis for the study of their potential use as biomarkers of the surgical remission of T2D in a larger series of severely obese patients.

Which predictors could effect on remission of type 2 diabetes mellitus after the metabolic surgery: A general perspective of current studies?

BACKGROUND

The alarming rise in the worldwide prevalence of obesity is paralleled by an increasing burden of type 2 diabetes mellitus (T2DM). Metabolic surgery is the most effective means of obtaining substantial and durable weight loss in individual obese patients with T2DM. There are randomized trials that justify the inclusion of metabolic surgery into the treatment algorithm for patients with T2DM, but remission rates of T2DM after metabolic surgery can display great variability.

AIM

To discuss the most commonly used surgical options including vertical sleeve gastrectomy, adjustable gastric banding, Roux-en-Y gastric bypass, and biliopancreatic diversion with duodenal switch.

METHODS

We also report from observational and randomized controlled studies on rate of remission of T2DM after the surgical procedures.

RESULTS

In light of the recent findings, metabolic surgery is a safe and effective treatment option for obese patient with T2DM, but further studies are needed to clarify better the rate of diabetes remission.

CONCLUSION

In light of the recent findings, metabolic surgery is a safe and effective treatment option for obese patients with T2DM, but further studies are needed to clarify better the rate of diabetes remission.

Metabolic shift precedes the resolution of inflammation in a cohort of patients undergoing bariatric and metabolic surgery

Bariatric and metabolic surgery has shown to promote weight loss and reduce systemic inflammation. However, the sequence and timing of events regarding metabolic improvement and inflammation resolution has been rarely explored. Furthermore, data on inflammatory markers of Th17 and Th1 cell responses after bariatric surgery is scarce. We conducted a prospective study in subjects with obesity that underwent bariatric and metabolic surgery, with follow-ups at 3 and 6 months. Anthropometric and metabolic markers such as insulin levels, HOMA-IR, and lipid parameters declined significantly 3 months after surgery; while hs-CRP, TNF-α, IL-1β, IL-6, and IL-8 serum concentrations decreased 6 months after the procedure. Concentrations of Th1 signature and driver cytokines, particularly IFN-γ, IL-12, and IL-18, and of Th17 driver IL-23 also decreased significantly after 6 months. Significant positive correlations between triglyceride levels and hs-CRP, IL-1β, and IFN-γ concentrations, and between Apo B and IFN-γ levels were observed 6 months after bariatric and metabolic surgery. In addition, BMI was associated with hs-CRP and TNF-α concentrations. Fat mass correlated with hs-CRP, TNF-α, and IL-12. Analysis of the temporality of metabolic and inflammatory events suggests that improvement in the metabolic status occurs before resolution of systemic inflammation and may be a requisite for the later event.

Comparative Effectiveness of Roux-en Y Gastric Bypass Versus Vertical Sleeve Gastrectomy for Sustained Remission of Type 2 Diabetes Mellitus

BACKGROUND

Bariatric surgery results in rapid weight loss and resolution of comorbidities such as type 2 diabetes mellitus (T2DM). We aimed to determine whether the type of surgical procedure-vertical sleeve gastrectomy (VSG) versus Roux-en-Y gastric bypass (RYGB)-was associated with sustained remission from T2DM, and to identify other independent predictors of sustained remission.

METHODS

Using the IBM MarketScan database of privately insured patients in the United States, we performed a retrospective cohort study on individuals aged 18-65 y with T2DM on hypoglycemic medication, who underwent either VSG or RYGB from 2010 to 2016. Remission was defined as no refill of antidiabetic medication 180 d after a patient's medication was expected to run out and recurrence as medication refill after at least 180 d of remission.

RESULTS

Of 5119 patients in our cohort, 4127 (81%) experienced remission of T2DM, and 816 (19.8%) of the 4127 patients experienced recurrence. Patients who underwent RYGB had a 24% (HR = 1.24, 95% CI: 1.16, 1.32) increased probability of achieving remission compared with VSG. RYGB had a 36% (HR = 0.64, 95% CI: 0.55, 0.74) decreased risk of recurrence compared with VSG. A higher number of diabetic medications at the time of surgery and a higher Charlson index score were associated with decreased probability of remission and an increased risk of recurrence of T2DM.

CONCLUSIONS

While both procedures are initially effective, RYGB may be better than VSG at providing lasting remission of T2DM.

Association between changes in bioactive osteocalcin and glucose homeostasis after biliopancreatic diversion

PURPOSE

Bone may regulate glucose homeostasis via uncarboxylated bioactive osteocalcin (ucOCN). This study explored whether changes in ucOCN and bone remodeling are associated with change in glucose homeostasis after biliopancreatic diversion (BPD).

METHODS

In this secondary exploratory analysis of a 1-year prospective observational study, 16 participants (11 men/5 women; 69% with type 2 diabetes; mean BMI 49.4 kg/m²) were assessed before, 3 days, 3 months and 12 months after BPD. Changes in plasma ucOCN and bone markers (C-terminal telopeptide (CTX), total osteocalcin (OCN)) were correlated with changes in insulin resistance or sensitivity indices (HOMA-IR; adipose tissue insulin resistance index (ADIPO-IR) and insulin sensitivity index (SI) from the hyperinsulinemic-euglycemic clamp), insulin secretion rate (ISR) from the hyperglycemic clamp, and disposition index (DI: SI × ISR) using Spearman correlations before and after adjustment for weight loss.

RESULTS

ucOCN was unchanged at 3 days but increased dramatically at 3 months (+257%) and 12 months (+498%). Change in ucOCN correlated significantly with change in CTX at 3 months (r = 0.62, p = 0.015) and 12 months (r = 0.64, p = 0.025) before adjustment for weight loss. It also correlated significantly with change in fasting insulin (r = -0.53, p = 0.035), HOMA-IR (r = -0.54, p = 0.033) and SI (r = 0.52, p = 0.041) at 3 days, and ADIPO-IR (r = -0.69, p = 0.003) and HbA_1c (r = -0.69, p = 0.005) at 3 months. Change in OCN did not correlate with any glucose homeostasis indices. Results were similar after adjustment for weight loss.

CONCLUSION

The increase in ucOCN may be associated with the improvement in insulin resistance after BPD, independently of weight loss. These findings need to be confirmed in larger, less heterogeneous populations.

Obesity Phenotypes, Diabetes, and Cardiovascular Diseases

This review addresses the interplay between obesity, type 2 diabetes mellitus, and cardiovascular diseases. It is proposed that obesity, generally defined by an excess of body fat causing prejudice to health, can no longer be evaluated solely by the body mass index (expressed in kg/m²) because it represents a heterogeneous entity. For instance, several cardiometabolic imaging studies have shown that some individuals who have a normal weight or who are overweight are at high risk if they have an excess of visceral adipose tissue-a condition often accompanied by accumulation of fat in normally lean tissues (ectopic fat deposition in liver, heart, skeletal muscle, etc). On the other hand, individuals who are overweight or obese can nevertheless be at much lower risk than expected when faced with excess energy intake if they have the ability to expand their subcutaneous adipose tissue mass, particularly in the gluteal-femoral area. Hence, excessive amounts of visceral adipose tissue and of ectopic fat largely define the cardiovascular disease risk of overweight and moderate obesity. There is also a rapidly expanding subgroup of patients characterized by a high accumulation of body fat (severe obesity). Severe obesity is characterized by specific additional cardiovascular health issues that should receive attention. Because of the difficulties of normalizing body fat content in patients with severe obesity, more aggressive treatments have been studied in this subgroup of individuals such as obesity surgery, also referred to as metabolic surgery. On the basis of the above, we propose that we should refer to obesities rather than obesity.

Bariatric Surgery Rapidly Decreases Cardiac Dietary Fatty Acid Partitioning and Hepatic Insulin Resistance Through Increased Intra-abdominal Adipose Tissue Storage and Reduced Spillover in Type 2 Diabetes

Reduced storage of dietary fatty acids (DFAs) in abdominal adipose tissues with enhanced cardiac partitioning has been shown in subjects with type 2 diabetes (T2D) and prediabetes. We measured DFA metabolism and organ partitioning using positron emission tomography with oral and intravenous long-chain fatty acid and glucose tracers during a standard liquid meal in 12 obese subjects with T2D before and 8-12 days after bariatric surgery (sleeve gastrectomy or sleeve gastrectomy and biliopancreatic diversion with duodenal switch). Bariatric surgery reduced cardiac DFA uptake from a median (standard uptake value [SUV]) 1.75 (interquartile range 1.39-2.57) before to 1.09 (1.04-1.53) after surgery (P = 0.01) and systemic DFA spillover from 56.7 mmol before to 24.7 mmol over 6 h after meal intake after surgery (P = 0.01), with a significant increase in intra-abdominal adipose tissue DFA uptake from 0.15 (0.04-0.31] before to 0.49 (0.20-0.59) SUV after surgery (P = 0.008). Hepatic insulin resistance was significantly reduced in close association with increased DFA storage in intra-abdominal adipose tissues (r = -0.79, P = 0.05) and reduced DFA spillover (r = 0.76, P = 0.01). We conclude that bariatric surgery in subjects with T2D rapidly reduces cardiac DFA partitioning and hepatic insulin resistance at least in part through increased intra-abdominal DFA storage and reduced spillover.

The Impact of Ethnicity on Metabolic Outcomes After Bariatric Surgery

BACKGROUND

Previous studies have demonstrated that ethnic minority patients experience significant metabolic improvements after bariatric surgery but less so than non-Hispanic whites. Previous research has primarily investigated differences between non-Hispanic white and black patients. Thus, there remains a need to assess differences in diabetic outcomes among other ethnic groups, including Hispanic and Asian patient populations.

MATERIALS AND METHODS

A retrospective analysis including 650 patients with type II diabetes mellitus (T2DM), who underwent either laparoscopic Roux-en-Y gastric bypass or laparoscopic sleeve gastrectomy (LSG) procedures, was conducted to understand ethnic disparities in diabetic metabolic outcomes, including weight loss, serum concentrations of glucose, fasting insulin, and hemoglobin A1c (HbA1c). Data were from a single academic institution in northern California. Ethnicity data were self reported. T2DM was defined as having one or more of the following criteria: a fasting glucose concentration >125 mg/dL, HbA1c >6.5%, or taking one or more diabetic oral medications. Diabetes resolution was defined as having a fasting glucose <125 mg/dL, a HbA1c <6.5%, and discontinuation of diabetic oral medications.

RESULTS

Within-group comparisons in all ethnic groups showed significant reductions in body mass index, body weight, fasting insulin, fasting glucose, and HbA1c by 6 mo, but Asian patients did not experience further improvement in body mass index or diabetic outcomes at the 12-mo visit. Black patients did not experience additional reductions in fasting insulin or glucose between the 6- and 12-mo visit and their HbA1c significantly increased. Nevertheless, the majority of patients had diabetes remission by the 12-mo postoperative visit (98%, 97%, 98%, and 92% in Non-Hispanic, Hispanic, black, and Asian, respectively).

CONCLUSIONS

The results of this study demonstrate that bariatric surgery serves as an effective treatment for normalizing glucose metabolism among patients with T2DM. However, this study suggests that additional interventions that support black and Asian patients with achieving similar metabolic outcomes as non-Hispanic white and Hispanic patients warrant further consideration.

Brown Adipose Tissue Energy Metabolism in Humans

The demonstration of metabolically active brown adipose tissue (BAT) in humans primarily using positron emission tomography coupled to computed tomography (PET/CT) with the glucose tracer 18-fluorodeoxyglucose (18FDG) has renewed the interest of the scientific and medical community in the possible role of BAT as a target for the prevention and treatment of obesity and type 2 diabetes (T2D). Here, we offer a comprehensive review of BAT energy metabolism in humans. Considerable advances in methods to measure BAT energy metabolism, including nonesterified fatty acids (NEFA), chylomicron-triglycerides (TG), oxygen, Krebs cycle rate, and intracellular TG have led to very good quantification of energy substrate metabolism per volume of active BAT in vivo. These studies have also shown that intracellular TG are likely the primary energy source of BAT upon activation by cold. Current estimates of BAT's contribution to energy expenditure range at the lower end of what would be potentially clinically relevant if chronically sustained. Yet, 18FDG PET/CT remains the gold-standard defining method to quantify total BAT volume of activity, used to calculate BAT's total energy expenditure. Unfortunately, BAT glucose metabolism better reflects BAT's insulin sensitivity and blood flow. It is now clear that most glucose taken up by BAT does not fuel mitochondrial oxidative metabolism and that BAT glucose uptake can therefore be disconnected from thermogenesis. Furthermore, BAT thermogenesis is efficiently recruited upon repeated cold exposure, doubling to tripling its total oxidative capacity, with reciprocal reduction of muscle thermogenesis. Recent data suggest that total BAT volume may be much larger than the typically observed 50-150 ml with 18FDG PET/CT. Therefore, the current estimates of total BAT thermogenesis, largely relying on total BAT volume using 18FDG PET/CT, may underestimate the true contribution of BAT to total energy expenditure. Quantification of the contribution of BAT to energy expenditure begs for the development of more integrated whole body in vivo methods.

The effect of metabolic surgery on nonobese patients (BMI<30 kg/m2) with type 2 diabetes: a systematic review

BACKGROUND

The influence of metabolic surgery on the glucose and lipid profiles of nonobese body mass index<30 kg/m² patients with type 2 diabetes, particularly the effect ≥1 year, remains unknown.

METHODS

PubMed and Ovid Embase were used.

SETTING

University hospitals.

RESULTS

In total, 21 studies including 921 patients were examined in this systematic review, the results of which revealed decrease in body mass index, waist circumference, fasting plasma glucose, glycosylated hemoglobin A1C, fasting C-peptide, fasting insulin, homeostasis model of assessment for insulin resistance index, triglycerides, total cholesterol, and low-density lipoprotein cholesterol. An increase in high-density lipoprotein cholesterol was also observed. The diabetes remission rates ranged from 13.3% to 90.2% according to 20 studies. The incidence of gastrointestinal bleeding ranged from 1% to 10% according to 9 studies. Four studies reported anemia after Roux-en-Y gastric bypass or one-anastomosis gastric bypass, with the incidence ranging from 8% to 33%.

CONCLUSIONS

Nonobese patients can achieve improvements in weight-related indices and glucose and lipid profiles in the short and medium term after metabolic surgery; however, the complications of metabolic surgery warrant further attention.

Abnormal Myocardial Dietary Fatty Acid Metabolism and Diabetic Cardiomyopathy

Patients with diabetes are at very high risk of hospitalization and death from heart failure. Increased prevalence of coronary heart disease, hypertension, autonomic neuropathy, and kidney failure all play a role in this increased risk. However, cardiac metabolic abnormalities are now recognized to play a role in this increased risk. Increased reliance on fatty acids to produce energy might predispose the diabetic heart to oxidative stress and ischemic damage. Intramyocellular accumulation of toxic lipid metabolites leads to a number of cellular abnormalities that might also contribute to cardiac remodelling and cardiac dysfunction. However, fatty acid availability from circulation and from intracellular lipid droplets to fuel the heart is critical to maintain its function. Fatty acids delivery to the heart is very complex and includes plasma nonesterified fatty acid flux as well as triglyceride-rich lipoprotein-mediated transport. Although many studies have shown a cross-sectional association between enhanced fatty acid delivery to the heart and reduction in left ventricular function in subjects with prediabetes and diabetes, these mechanisms change very rapidly during type 2 diabetes treatment. The present review focuses on the role of fatty acids in cardiac function, with particular emphasis on the possible role of early abnormalities of dietary fatty acid metabolism in the development of diabetic cardiomyopathy.

Pancreatic Exocrine Insufficiency after Bariatric Surgery

Morbid obesity is a lifelong disease, and all patients require complementary follow-up including nutritional surveillance by a multidisciplinary team after bariatric procedures. Pancreatic exocrine insufficiency (PEI) refers to an insufficient secretion of pancreatic enzymes and/or sodium bicarbonate. PEI is a known multifactorial complication after upper gastrointestinal surgery, and might constitute an important clinical problem due to the large number of bariatric surgical procedures in the world. Symptoms of PEI often overlap with sequelae of gastric bypass, making the diagnosis difficult. Steatorrhea, weight loss, maldigestion and malabsorption are pathognomonic for both clinical conditions. Altered anatomy after bypass surgery can make the diagnostic process even more difficult. Fecal elastase-1 (FE1) is a useful diagnostic test. PEI should be considered in all patients after bariatric surgery with prolonged gastrointestinal complaints that are suggestive of maldigestion and/or malabsorption. Appropriate pancreatic enzyme replacement therapy should be part of the treatment algorithm in patients with confirmed PEI or symptoms suggestive of this complication.