Glucagon-like peptide-1 and the islet beta-cell: augmentation of cell proliferation and inhibition of apoptosis

Glucagon-like peptide-1 receptor: mechanisms and advances in therapy

The glucagon-like peptide-1 (GLP-1) receptor, known as GLP-1R, is a vital component of the G protein-coupled receptor (GPCR) family and is found primarily on the surfaces of various cell types within the human body. This receptor specifically interacts with GLP-1, a key hormone that plays an integral role in regulating blood glucose levels, lipid metabolism, and several other crucial biological functions. In recent years, GLP-1 medications have become a focal point in the medical community due to their innovative treatment mechanisms, significant therapeutic efficacy, and broad development prospects. This article thoroughly traces the developmental milestones of GLP-1 drugs, from their initial discovery to their clinical application, detailing the evolution of diverse GLP-1 medications along with their distinct pharmacological properties. Additionally, this paper explores the potential applications of GLP-1 receptor agonists (GLP-1RAs) in fields such as neuroprotection, anti-infection measures, the reduction of various types of inflammation, and the enhancement of cardiovascular function. It provides an in-depth assessment of the effectiveness of GLP-1RAs across multiple body systems-including the nervous, cardiovascular, musculoskeletal, and digestive systems. This includes integrating the latest clinical trial data and delving into potential signaling pathways and pharmacological mechanisms. The primary goal of this article is to emphasize the extensive benefits of using GLP-1RAs in treating a broad spectrum of diseases, such as obesity, cardiovascular diseases, non-alcoholic fatty liver disease (NAFLD), neurodegenerative diseases, musculoskeletal inflammation, and various forms of cancer. The ongoing development of new indications for GLP-1 drugs offers promising prospects for further expanding therapeutic interventions, showcasing their significant potential in the medical field.

Chronic exposure to incretin metabolites GLP-1(9-36) and GIP(3-42) affect islet morphology and beta cell health in high fat fed mice

The incretin hormones, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), are rapidly degraded by dipeptidyl peptidase-4 (DPP-4) to their major circulating metabolites GLP-1(9-36) and GIP(3-42). This study investigates the possible effects of these metabolites, and the equivalent exendin molecule Ex(9-39), on pancreatic islet morphology and constituent alpha and beta cells in high-fat diet (HFD) fed mice. Male Swiss TO-mice (6-8 weeks-old) were maintained on a HFD or normal diet (ND) for 4 months and then received twice-daily subcutaneous injections of GLP-1(9-36), GIP(3-42), Ex(9-39) (25 nmol/kg bw) or saline vehicle (0.9% (w/v) NaCl) over a 60-day period. Metabolic parameters were monitored and excised pancreatic tissues were used for immunohistochemical analysis. Body weight and assessed metabolic indices were not changed by peptide administration. GLP-1(9-36) significantly (p<0.001) increased islet density per mm2 tissue, that was decreased (p<0.05) by HFD. Islet, beta and alpha cell areas were increased (p<0.01) following HFD and subsequently reduced (p<0.01-p<0.001) by GIP(3-42) and Ex(9-39) treatment. While GLP-1(9-36) did not affect islet and beta cell areas in HFD mice, it significantly (p<0.01) decreased alpha cell area. Compared to ND and HFD mice, GIP(3-42) treatment significantly (p<0.05) increased beta cell proliferation. Whilst HFD increased (p<0.001) beta cell apoptosis, this was reduced (p<0.01-p<0.001) by both GLP-1(9-36) and GIP(3-42). These data indicate that the major circulating forms of GLP-1 and GIP, namely GLP-1(9-36) and GIP(3-42) previously considered largely inactive, may directly impact pancreatic morphology, with an important protective effect on beta cell health under conditions of beta cell stress.

Gαz-independent and -dependent Improvements With EPA Supplementation on the Early Type 1 Diabetes Phenotype of NOD Mice

Prostaglandin E2 (PGE2) is a key mediator of inflammation and is derived from the omega-6 polyunsaturated fatty acid, arachidonic acid (AA). In the β-cell, the PGE2 receptor, Prostaglandin EP3 receptor (EP3), is coupled to the unique heterotrimeric G protein alpha subunit, Gɑz to reduce the production of cyclic adenosine monophosphate (cAMP), a key signaling molecule that activates β-cell function, proliferation, and survival pathways. Nonobese diabetic (NOD) mice are a strong model of type 1 diabetes (T1D), and NOD mice lacking Gɑz are protected from hyperglycemia. Therefore, limiting systemic PGE2 production could potentially improve both the inflammatory and β-cell dysfunction phenotype of T1D. Here, we sought to evaluate the effect of eicosapentaenoic acid (EPA) feeding, which limits PGE2 production, on the early T1D phenotype of NOD mice in the presence and absence of Gαz. Wild-type and Gαz knockout NOD mice were fed a control or EPA-enriched diet for 12 weeks, beginning at age 4 to 5 weeks. Oral glucose tolerance, splenic T-cell populations, islet cytokine/chemokine gene expression, islet insulitis, measurements of β-cell mass, and measurements of β-cell function were quantified. EPA diet feeding and Gɑz loss independently improved different aspects of the early NOD T1D phenotype and coordinated to alter the expression of certain cytokine/chemokine genes and enhance incretin-potentiated insulin secretion. Our results shed critical light on the Gαz-dependent and -independent effects of dietary EPA enrichment and provide a rationale for future research into novel pharmacological and dietary adjuvant therapies for T1D.

Berberine-induced glucagon-like peptide-1 and its mechanism for controlling type 2 diabetes mellitus: a comprehensive pathway review

Introduction: A growing number of studies have thus far showed the association between type 2 diabetes mellitus (DM) and the intestinal microbiome homoeostasis. As reported, the gut microflora can be significantly different in patients with type 2 DM (T2DM) compared to those in healthy individuals.Methods: The authors collected the relevant articles published until 2022 and these are carefully selected from three scientific databases based on keywords.Discussion: This review highlights research on the anti-diabetic properties of berberine (BBR)-induced glucagon-like peptide-1 (GLP-1), as a glucose-lowering factor and a balance regulator in the microbial flora of the intestines, which plays an important role in adjusting the signalling pathways affecting insulin secretion.Results: Considering the anti-diabetic characteristics of the BBR-induced GLP-1, BBR makes a promising complementary treatment for reducing the clinical symptoms of DM by reducing the hyperglycaemia. Berberin might be a safe and effective drug for T2DM with little or no adverse effects.HighlightsBerberine induces GLP-1 insulin secretion by PLC2 pathway in the intestinalBerberine-induced GLP-1 decreases mitochondrial stress and relocates cytochrome c out of the mitochondria.Berberine induces GLP-1 secretion in the intestine by altering the bacterial profile, thus could possibly lighten diabetes symptomsBerberine-induced SCFA production, SCFA causes GLP-1 secretion from the intestinal L-Cell.Preventing mitochondrial damage, reducing adipose tissue fat, and reducing oxidative stress are thus among the results of BBR-induced GLP-1.The lower costs of BBR, and its limited side effects and higher availability, make it a promising supplementary medicine for DM.

MK2 Promotes the Development and Progression of Pancreatic Neuroendocrine Tumors Mediated by Macrophages and Metabolomic Factors

Cases of pancreatic neuroendocrine tumors (PNETs) are growing in number, and new treatment options are needed in order to improve patient outcomes. The mitogen-activated protein kinase-activated protein kinase 2 (MK2) is a crucial regulator of cytokine/chemokine production. The significance of MK2 expression and signaling pathway mediated by MK2 in PNETs has not been investigated. To characterize the impact of MK2 on PNET growth, we used the RipTag2 transgenic murine model of PNETs, and we developed a primary PNET cell line for both in vitro and in vivo studies. In the transgenic murine model of PNETs, we found that MK2 inhibition improves survival of mice and prevents PNET progression. MK2 blockade abolished cytokine/chemokine production, which was related to macrophage function. A role for MK2 in the regulation of metabolic factor secretion in PNETs was identified, making this the first study to identify a potential role for the MK2 pathway in regulation of tumor metabolism. Moreover, using an in vitro approach and allograft model of PNETs, we were able to show that macrophages with MK2 depletion exhibit increased cytotoxicity against PNET cells and substantially decreased production of pro-inflammatory cytokines and chemokines, as well as metabolic factors. Taken together, our work identifies MK2 as a potent driver of immune response and metabolic effectors in PNETs, suggesting it is a potential therapeutic target for patients with PNETs.

Reprogramming—Evolving Path to Functional Surrogate β-Cells

Numerous cell sources are being explored to replenish functional β-cell mass since the proof-of -concept for cell therapy of diabetes was laid down by transplantation of islets. Many of these cell sources have been shown to possess a degree of plasticity permitting differentiation along new lineages into insulin-secreting β-cells. In this review, we explore emerging reprograming pathways that aim to generate bone fide insulin producing cells. We focus on small molecules and key transcriptional regulators that orchestrate phenotypic conversion and maintenance of engineered cells.

Modifying a Hydroxyl Patch in Glucagon-like Peptide 1 Produces Biased Agonists with Unique Signaling Profiles

Glucagon-like peptide-1 (GLP-1) lowers blood glucose by inducing insulin but also has other poorly understood properties. Here, we show that hydroxy amino acids (Thr11, Ser14, Ser17, Ser18) in GLP-1(7-36) act in concert to direct cell signaling. Mutating any single residue to alanine removes one hydroxyl group, thereby reducing receptor affinity and cAMP 10-fold, with Ala11 or Ala14 also reducing β-arrestin-2 10-fold, while Ala17 or Ala18 also increases ERK1/2 phosphorylation 5-fold. Multiple alanine mutations more profoundly bias signaling, differentially silencing or restoring one or more signaling properties. Mutating three serines silences only ERK1/2, the first example of such bias. Mutating all four residues silences β-arrestin-2, ERK1/2, and Ca²⁺ maintains the ligand and receptor at the membrane but still potently stimulates cAMP and insulin secretion in cells and mice. These novel findings indicate that hydrogen bonding cooperatively controls cell signaling and highlight an important regulatory hydroxyl patch in hormones that activate class B G protein-coupled receptors.

GIP receptor antagonist treatment causes a reduction in weight gain in ovariectomised high fat diet-fed mice

Background and purpose

The incretin hormone, gastric inhibitory peptide/glucose‐dependent insulinotropic polypeptide (GIP), secreted by the enteroendocrine K‐cells in the proximal intestine, may regulate lipid metabolism and adiposity, but its exact role in these processes is unclear.

Experimental approach

We characterized in vitro and in vivo antagonistic properties of a novel GIP analogue, mGIPAnt‐1. We further assessed the in vivo pharmacokinetic profile of this antagonist, as well as its ability to affect high‐fat diet (HFD)‐induced body weight gain in ovariectomised mice during an 8‐week treatment period.

Key results

mGIPAnt‐1 showed competitive antagonistic properties to the GIP receptor in vitro as it inhibited GIP‐induced cAMP accumulation in COS‐7 cells. Furthermore, mGIPAnt‐1 was capable of inhibiting GIP‐induced glucoregulatory and insulinotropic effects in vivo and has a favourable pharmacokinetic profile with a half‐life of 7.2 h in C57Bl6 female mice. Finally, sub‐chronic treatment with mGIPAnt‐1 in ovariectomised HFD mice resulted in a reduction of body weight and fat mass.

Conclusion and Implications

mGIPAnt‐1 successfully inhibited acute GIP‐induced effects in vitro and in vivo and sub‐chronically induces resistance to HFD‐induced weight gain in ovariectomised mice. Our results support the development of GIP antagonists for the therapy of obesity.

Neuroprotective Mechanisms of Glucagon-Like Peptide-1-Based Therapies in Ischemic Stroke: An Update Based on Preclinical Research

The public and social health burdens of ischemic stroke have been increasing worldwide. Hyperglycemia leads to a greater risk of stroke. This increased risk is commonly seen among patients with diabetes and is in connection with worsened clinical conditions and higher mortality in patients with acute ischemic stroke (AIS). Therapy for stroke focuses mainly on restoring cerebral blood flow (CBF) and ameliorating neurological impairment caused by stroke. Although choices of stroke treatment remain limited, much advance have been achieved in assisting patients in recovering from ischemic stroke, along with progress of recanalization therapy through pharmacological and mechanical thrombolysis. However, it is still necessary to develop neuroprotective therapies for AIS to protect the brain against injury before and during reperfusion, prolong the time window for intervention, and consequently improve neurological prognosis. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are broadly regarded as effective drugs in the treatment of type 2 diabetes mellitus (T2DM). Preclinical data on GLP-1 and GLP-1 RAs have displayed an impressive neuroprotective efficacy in stroke, Parkinson's disease (PD), Alzheimer's disease (AD), Amyotrophic lateral sclerosis (ALS), and other neurodegenerative diseases. Based on the preclinical studies in the past decade, we review recent progress in the biological roles of GLP-1 and GLP-1 RAs in ischemic stroke. Emphasis will be placed on their neuroprotective effects in experimental models of cerebral ischemia stroke at cellular and molecular levels.

Fructose prevents the development of hyperglycemia in WBN/Kob diabetic fatty rats via maintaining high insulin levels

Fructose is considered to negatively affect type 2 diabetes mellitus (T2DM); however, there are contradictory reports. The present study aimed to elucidate the effects of fructose-rich diet (FRD) on glucose metabolism of WBN/Kob fatty diabetic (WBKDF) rats, a spontaneous T2DM model, and Wistar rats. WBKDF and Wistar rats were fed either FRD or standard diet (STD) for 4 weeks. The food intake, body weight, plasma glucose and insulin were measured weekly. After the 4-week challenge, rats were subjected to an intravenous glucose tolerance test (IVGTT). The liver and pancreas were used for histological analysis. The 4-week challenge of FRD in Wistar rats did not cause hyperglycemia, but increased insulin resistance (HOMA-IR). Feeding WBKDF rats with a FRD accelerated obesity but prevented the onset of severe hyperglycemia via maintaining high plasma insulin levels. HOMA-IR in WBKDF rats was not changed by FRD feeding. IVGTT revealed that FRD feeding in Wistar rats did not affect glucose tolerance, but slightly increased the plasma insulin level. In contrast, FRD feeding in WBKDF rats significantly reduced the glucose tolerance, but insulin response was not improved. FRD feeding did not alter the beta cell area in Wistar rats, but significantly increased it in WBKDF rats. In conclusion, FRD caused insulin resistance in Wistar rats, suggesting that fructose overconsumption is a risk factor for T2DM, whereas FRD inhibited severe hyperglycemia by maintaining high insulin levels　in WBKDF rats. Fructose may be a beneficial sugar for T2DM patients with severe obesity-induced insulin resistance.

Glucagon-Like Peptide-1 Receptor Agonists and Dual Glucose-Dependent Insulinotropic Polypeptide/Glucagon-Like Peptide-1 Receptor Agonists in the Treatment of Obesity/Metabolic Syndrome, Prediabetes/Diabetes and Non-Alcoholic Fatty Liver Disease-Current Evidence

The obesity pandemic is accompanied by increased risk of developing metabolic syndrome (MetS) and related conditions: non-alcoholic fatty liver disease (NAFLD)/non-alcoholic steatohepatitis (NASH), type 2 diabetes mellitus (T2DM) and cardiovascular (CV) disease (CVD). Lifestyle, as well as an imbalance of energy intake/expenditure, genetic predisposition, and epigenetics could lead to a dysmetabolic milieu, which is the cornerstone for the development of cardiometabolic complications. Glucagon-like peptide-1 (GLP-1) receptor agonists (RAs) and dual glucose-dependent insulinotropic polypeptide (GIP)/GLP-1 RAs promote positive effects on most components of the "cardiometabolic continuum" and consequently help reduce the need for polypharmacy. In this review, we highlight the main pathophysiological mechanisms and risk factors (RFs), that could be controlled by GLP-1 and dual GIP/GLP-1 RAs independently or through synergism or differences in their mode of action. We also address the evidence on the use of GLP-1 and dual GIP/GLP-1 RAs in the treatment of obesity, MetS and its related conditions (prediabetes, T2DM and NAFLD/NASH). In conclusion, GLP-1 RAs have already been established for the treatment of T2DM, obesity and cardioprotection in T2DM patients, while dual GIP/GLP-1 RAs appear to have the potential to possibly surpass them for the same indications. However, their use in the prevention of T2DM and the treatment of complex cardiometabolic metabolic diseases, such as NAFLD/NASH or other metabolic disorders, would benefit from more evidence and a thorough clinical patient-centered approach. There is a need to identify those patients in whom the metabolic component predominates, and whether the benefits outweigh any potential harm.

In Vitro and In Vivo Antidiabetic Potential of Monoterpenoids: An Update

Diabetes mellitus (DM) is a chronic metabolic condition characterized by persistent hyperglycemia due to insufficient insulin levels or insulin resistance. Despite the availability of several oral and injectable hypoglycemic agents, their use is associated with a wide range of side effects. Monoterpenes are compounds extracted from different plants including herbs, vegetables, and fruits and they contribute to their aroma and flavor. Based on their chemical structure, monoterpenes are classified into acyclic, monocyclic, and bicyclic monoterpenes. They have been found to exhibit numerous biological and medicinal effects such as antipruritic, antioxidant, anti-inflammatory, and analgesic activities. Therefore, monoterpenes emerged as promising molecules that can be used therapeutically to treat a vast range of diseases. Additionally, monoterpenes were found to modulate enzymes and proteins that contribute to insulin resistance and other pathological events caused by DM. In this review, we highlight the different mechanisms by which monoterpenes can be used in the pharmacological intervention of DM via the alteration of certain enzymes, proteins, and pathways involved in the pathophysiology of DM. Based on the fact that monoterpenes have multiple mechanisms of action on different targets in in vitro and in vivo studies, they can be considered as lead compounds for developing effective hypoglycemic agents. Incorporating these compounds in clinical trials is needed to investigate their actions in diabetic patients in order to confirm their ability in controlling hyperglycemia.

Lessons from bariatric surgery: Can increased GLP-1 enhance vascular repair during cardiometabolic-based chronic disease?

Type 2 diabetes (T2D) and obesity represent entangled pandemics that accelerate the development of cardiovascular disease (CVD). Given the immense burden of CVD in society, non-invasive prevention and treatment strategies to promote cardiovascular health are desperately needed. During T2D and obesity, chronic dysglycemia and abnormal adiposity result in systemic oxidative stress and inflammation that deplete the vascular regenerative cell reservoir in the bone marrow that impairs blood vessel repair and exacerbates the penetrance of CVD co-morbidities. This novel translational paradigm, termed 'regenerative cell exhaustion' (RCE), can be detected as the depletion and dysfunction of hematopoietic and endothelial progenitor cell lineages in the peripheral blood of individuals with established T2D and/or obesity. The reversal of vascular RCE has been observed after administration of the sodium-glucose cotransporter-2 inhibitor (SGLT2i), empagliflozin, or after bariatric surgery for severe obesity. In this review, we explore emerging evidence that links improved dysglycemia to a reduction in systemic oxidative stress and recovery of circulating pro-vascular progenitor cell content required for blood vessel repair. Given that bariatric surgery consistently increases systemic glucagon-like-peptide 1 (GLP-1) release, we also focus on evidence that the use of GLP-1 receptor agonists (GLP-1RA) during obesity may act to inhibit the progression of systemic dysglycemia and adiposity, and indirectly reduce inflammation and oxidative stress, thereby limiting the impact of RCE. Therefore, therapeutic intervention with currently-available GLP-1RA may provide a less-invasive modality to reverse RCE, bolster vascular repair mechanisms, and improve cardiometabolic risk in individuals living with T2D and obesity.

Future perspectives in diabesity treatment: Semaglutide, a glucagon-like peptide 1 receptor agonist (Review)

Given their endemic prevalence in the past decades, obesity and type 2 diabetes mellitus (T2DM) have become a major sanitary burden with an important economic impact. Novel treatment options have been designed with the aim of reducing the numerous complications associated with these metabolic disorders, as well as reducing morbidity and mortality and improving the quality of life of those who suffer from these disorders. Glucagon-like peptide 1 receptor agonists (GLP-1 RAs) are among the most modern therapeutics that target ‘diabesity’, a term used to describe the pathophysiological link between obesity and T2DM. Their glucose-lowering effects are mainly attributed to glucose-dependent insulin secretion, glucagon inhibition and decreased gastric emptying. Given the effects on the central nervous system, GLP-1 RA usage may lead to body weight reduction. GLP-1 RAs are classified based on their pharmacokinetic properties as short- and long-acting agents, with both types being administered by subcutaneous injection. The latest agent from this drug class approved for use in T2DM is semaglutide, a long-acting compound that is the only GLP-1 RA available as an oral pill. The present narrative review highlights the most recently published data on the effects and safety of semaglutide in diabetic obesity, also emphasizing its cardiovascular benefits and potential side effects. In addition, an overview of the role of semaglutide in the treatment of non-diabetic obesity is provided.

A 2021 Update on the Use of Liraglutide in the Modern Treatment of 'Diabesity': A Narrative Review

Obesity and type 2 diabetes mellitus have become a significant public health problem in the past decades. Their prevalence is increasing worldwide each year, greatly impacting the economic and personal aspects, mainly because they frequently coexist, where the term “diabesity” may be used. The drug class of glucagon-like peptide 1 receptor agonists (GLP-1 RAs) is one of the most modern therapy options in managing these metabolic disorders. This review focuses on the effects of liraglutide, a long-acting GLP-1 RA, in diabesity and non-diabetic excess weight. This drug class improves glycemic control by enhancing insulin secretion from the beta-pancreatic cells and inhibiting glucagon release. Furthermore, other effects include slowing gastric emptying, increasing postprandial satiety, and reducing the appetite and food consumption by influencing the central nervous system, with weight reduction effects. It also reduces cardiovascular events and has positive effects on blood pressure and lipid profile. A lower-dose liraglutide (1.2 or 1.8 mg/day) is used in patients with diabetes, while the higher dose (3.0 mg/day) is approved as an anti-obesity drug. In this review, we have summarized the role of liraglutide in clinical practice, highlighting its safety and efficacy as a glucose-lowering agent and a weight-reduction drug in patients with and without diabetes.

Continuous stimulation of dual-function peptide PGLP-1-VP inhibits the morbidity and mortality of NOD mice through anti-inflammation and immunoregulation

Multiple animal and human studies have shown that administration of GLP-1RA can enhance β-cell recovery, reduce insulin dosage, reduce HbA1c content in the blood, reduce the risk of hypoglycemia and reduce inflammation. In the NOD mouse model, peptide VP treatment can prevent and treat type 1 diabetes through immunomodulation. Therefore, we designed a new dual-functional PGLP-1-VP, which is expected to combine the anti-inflammatory effect of PGLP-1 and the immunomodulatory effect of VP peptide. In streptozotocin-induced hyperglycemic mice model, we demonstrated that PGLP-1-VP can act as a GLP-1R agonist to improve hyperglycemia and increase insulin sensitivity. In the NOD mouse model, PGLP-1-VP treatment reduced morbidity, mortality, and pancreatic inflammation, and showed superior effect to PGLP-1 or VP treatment alone, confirming that PGLP-1-VP may act as a dual-function peptide. PGLP-1-VP provided immunomodulatory effect through increasing Th2 cell percentage and balancing the ratio of Th2/Th1 in spleen and PLN, similar to P277 and VP. Additionally, PGLP-1-VP and PGLP-1 act the anti-inflammation by increasing Treg cells and TGF-β1 content like DPP-IV inhibitor. Taken together, our data shows that the dual-functional PGLP-1-VP reduces morbidity and mortality in the NOD model, suggesting a potential role in preventing and treating type 1 diabetes.

Local administration of high-dose diabetes medicine exendin-4 inhibits orthodontic tooth movement in mice

OBJECTIVES

To investigate the effects of exendin-4 on orthodontic tooth movement distance, root resorption, and expression levels of osteoclast-related cytokines in a mouse model.

MATERIALS AND METHODS

A 10-g NiTi coil spring was placed between the anterior alveolar bone and upper left first molar of 8-week-old male C57BL/6 mice. Twenty microliters of exendin-4 solution (containing 0.2 μg, 4 μg, or 20 μg exendin-4) or phosphate-buffered saline (PBS) were injected on the buccal side of the upper left first molar at 2-day intervals (4 mice per group). Mice were sacrificed on day 12; silicone impressions were taken to record tooth movement distance. The left maxillae of the PBS and 20 μg exendin-4 groups were also excised for histological analysis and quantitative reverse transcription polymerase chain reaction analysis.

RESULTS

Orthodontic tooth movement distance was smaller in the 20 μg exendin-4 group than in the PBS group (P < .01). Compared with the PBS group, the 20 μg exendin-4 group showed lower osteoclast number (P < .05), odontoclast number (P < .05), and root resorption surface percentage (P < .05). Relative to maxillae with PBS injections, maxillae with 20 μg exendin-4 injections had lower receptor activator of nuclear factor kappa-B ligand (RANKL) mRNA expression (P < .05), TNF-α mRNA expression (P < .05), and RANKL/osteoprotegerin (OPG) ratio (P < .01). There were no differences in the expression of OPG mRNA.

CONCLUSIONS

Exendin-4 inhibits orthodontic tooth movement. Therefore, additional attention is needed for orthodontic patients who receive exendin-4 for diabetes treatment. GLP-1 receptor may be a treatment target for patients with severe root resorption.

The Short-Term Effects of Transit Bipartition with Sleeve Gastrectomy and Distal-Roux-en-Y Gastric Bypass on Glycemic Control, Weight Loss, and Nutritional Status in Morbidly Obese and Type 2 Diabetes Mellitus Patients

PURPOSE

The aim of this study was to compare the postoperative metabolic and nutritional outcomes after transit bipartition with sleeve gastrectomy (TB-SG) and distal-Roux-en-Y gastric bypass (D-RYGB).

MATERIALS AND METHODS

A retrospective evaluation was made of 109 morbidly obese patients who underwent TB-SG or D-RYGB. Primary outcomes included metabolic variables such as glycemic control and serum lipid levels, and secondary outcomes consisted of nutritional deficiencies and weight loss after surgical procedures.

RESULTS

During the study period, 83 and 26 patients underwent D-RYGB and TB-SG, respectively. The preoperative characteristics and nutritional status of the groups were similar. D-RYGB resulted in significantly higher weight loss rates in the first 3 months, but the percentage of excess weight loss (EWL %) was not different in the 12-month follow-up period. Although D-RYGB provided faster glycemic control due to early weight loss, there was no difference between the two groups. At the end of the follow-up period, the TB-SG was associated with significantly less deficiency of vitamin D, vitamin B12, iron, and folic acid. Anastomosis leakage was more common in the D-RYGB technique. The overall complication rates of the groups were similar.

CONCLUSION

TB-SG is a safe and effective alternative to D-RYGB for the treatment of obesity-related metabolic disorders with fewer nutritional deficiencies.

EGLP-1 lowers body weight better than exendin-4 by reducing food intake and increasing basal energy expenditure in diet-induced obese mice

It is well known that GLP-1 activates GLP-1R to reduce body weight by inhibiting eating. GLP-1 is cleaved by the neutral endopeptidase (NEP) 24.11 into a pentapeptide GLP-1 (32-36) amide, which increases basal energy expenditure and inhibits weight gain in obese mice. It is well known that GLP-1 analogs can reduce weight by suppressing eating. However, there are few reports of reducing weight through the dual effects of inhibiting eating and increasing basic energy. Here, we report the peptide EGLP-1, a GLP-1 analogue, which can reduce food intake and increase basal energy expenditure. In C2C12 myotubes, EGLP-1 can increase both phosphorylation of acetyl CoA carboxylase (ACC) and the ratio between phosphorylation of ACC and the total expression of ACC (pACC/ACC). In diet-induced obese mice, EGLP-1 is more effective than exendin-4 in reducing body weight, reducing fat mass and improving hepatic steatosis. At the same time, EGLP-1 can improve hyperglycemia, reduce food intake, and improve insulin resistance, just like exendin-4. In addition, EGLP-1, not exendin-4, can improve physiological parameters associated with lipid metabolism and increase oxygen consumption by increasing uncoupling proteins 3 (UCP3) expression and pACC/ACC ratio in skeletal muscle. Taken together, this data showed that EGLP-1 is able to reduce body weight by reducing food intake and increasing basal energy expenditure, suggesting it may be more effective in treating diabetic and non-diabetic overweight or obese people than pure GLP-1R agonist exendin-4.

Glucagon-Like Peptide 1 Attenuates Lipotoxicity-Induced Islet Dysfunction in ApoE-/- Mice

AIM

Glucagon-like peptide-1 (GLP1) is known to decrease glucagon release and may be beneficial for the reduction of elevated blood glucose. However, its role and mechanism of action in diabetes remain elusive. This study aimed to examine the function of GLP1 and analyze the mechanism of effect that GLP1exerts on inducible nitric oxide synthase (iNOS) in diabetic mice.

METHODS

A diabetes model was established in ApoE-/- mice fed a high-fat diet and treated with GLP1 and/or lentivirus-expressing PARP1. PARP1, iNOS, and inflammatory factors in islets were detected by Western blot and ELISA. Islet α cells and β cells and CD8+ T lymphocytes were detected by immunostaining. Islet-cell apoptosis was detected by TUNEL.

RESULTS

GLP1 inhibited the expression of PARP1 and iNOS in islets, alleviated decrease in β cells, and suppressed cell apoptosis induced by the high-fat diet. Moreover, GLP1 recovered the decline in insulin sensitivity and glucose tolerance in ApoE-/- mice fed the high-fat diet, and the effects of GLP1 were related to the inhibition of COX2 and NFκB expression.

CONCLUSION

GLP1 significantly alleviated the decrease in β-cell numbers, suppressed β-cell apoptosis induced by the high-fat diet, inhibited the expression of iNOS, and alleviated inflammatory islet injury via inhibiting the COX2-NFκB pathway.

Can dipeptidyl peptidase-4 inhibitors treat cognitive disorders?

The linkage of neurodegenerative diseases with insulin resistance (IR) and type 2 diabetes mellitus (T2DM), including oxidative stress, mitochondrial dysfunction, excessive inflammatory responses and abnormal protein processing, and the correlation between cerebrovascular diseases and hyperglycemia has opened a new window for novel therapeutics for these cognitive disorders. Various antidiabetic agents have been studied for their potential treatment of cognitive disorders, among which the dipeptidyl peptidase-4 (DPP-4) inhibitors have been investigated more recently. So far, DPP-4 inhibitors have demonstrated neuroprotection and cognitive improvements in animal models, and cognitive benefits in diabetic patients with or without cognitive impairments. This review aims to summarize the potential mechanisms, advantages and limitations, and currently available evidence for developing DPP-4 inhibitors as a treatment of cognitive disorders.

The Synergistic Effect of Glucagon-Like Peptide-1 and Chamomile Oil on Differentiation of Mesenchymal Stem Cells into Insulin-Producing Cells

OBJECTIVE

Glucagon-like peptide-1 (GLP-1) has attracted tremendous attention for treatment of diabetes. Likewise, it seems that active ingredients of chamomile oil might have anti-diabetic effects. This work was conducted to investigate the effects of the combination of GLP-1 and chamomile oil on differentiation of mesenchymal stem cells (MSCs) into functional insulin-producing cells (IPCs).

MATERIALS AND METHODS

In this experimental study, adipose MSCs derived from the adult male New Zealand white rabbits were assigned into four groups: control (without any treatment); GLP-1 (in which cells were treated with 10 nM GLP-1 every other day for 5 days); chamomile oil (in which cells were treated with 100 ug/ml Matricaria chamomilla L. flower oil every other day for 5 days); and GLP-1+ chamomile oil (in which cells were treated with 10 nM GLP-1 and 100 μg/ml M. chamomilla flower oil every other day for 5 days). Characterization of isolated MSCs was performed using flow cytometry, Alizarin red S staining and Oil red O staining. The expressions of genes specific for IPCs were measured using reverse transcriptase-polymerase chain reaction (RT-PCR) assay. Measurement of insulin and the cleaved connecting peptide (C-peptide) in response to different concentrations of glucose, were performed using ELISA kits.

RESULTS

Our results demonstrated that isolated cells highly expressed MSC markers and were able to differentiate into osteocytes and adipocytes. Additionally, using GLP-1 in combination with chamomile oil exhibited higher levels of IPCs gene markers including NK homeobox gene 2.2 (NKX-2.2), paired box gene 4 (PAX4), insulin (INS) and pancreatic duodenal homeobox-1 (PDX1) as well as insulin and C-peptide secretion in response to different glucose concentrations compared to GLP-1 or chamomile oil alone (P<0.05).

CONCLUSION

Collectively, these findings establish a substantial foundation for using peptides in combination with natural products to obtain higher efficiency in regenerative medicine and peptide therapy.

Remission of Type 2 Diabetes Mellitus after Bariatric Surgery: Fact or Fiction?

Although type 2 diabetes mellitus (T2DM) has been traditionally viewed as an intractable chronic medical condition, accumulating evidence points towards the notion that a complete remission of T2DM is feasible following a choice of medical and/or surgical interventions. This has been paralleled by increasing interest in the establishment of a universal definition for T2DM remission which, under given circumstances, could be considered equivalent to a “cure”. The efficacy of bariatric surgery in particular for achieving glycemic control has highlighted surgery as a candidate curative intervention for T2DM. Herein, available evidence regarding available surgical modalities and the mechanisms that drive metabolic amelioration after bariatric surgery are reviewed. Furthermore, reports from observational and randomized studies with regard to T2DM remission are reviewed, along with concepts relevant to the variety of definitions used for T2DM remission and other potential sources of discrepancy in success rates among different studies.

Addition of glucagon-like peptide-1 receptor agonist therapy to insulin in C-peptide-positive patients with type 1 diabetes

We aimed to test the hypothesis that addition of glucagon-like peptide-1 receptor agonists (GLP-1RAs) to insulin in C-peptide-positive patients with type 1 diabetes (T1D) will result in a reduction in glycated haemoglobin (HbA1c) with reduced insulin requirements and a rise in C-peptide concentrations. We conducted a retrospective analysis of 11 normal-weight patients with T1D consecutively treated with a GLP-1RA in addition to insulin. Paired t tests were used to compare the changes in HbA1c, insulin doses, body weight, body mass index, and C-peptide concentrations prior to and 12 ± 1 weeks after GLP-1RA therapy. At the end of 12 ± 1 weeks of GLP-1RA therapy, HbA1c fell from 10.74 ± 0.96% (95 ± 10.5 mmol/mol) to 7.4 ± 0.58% (58 ± 6.3mmol/mol) (P < 0.01), body weight fell from 71 ± 2.0 to 69 ± 2 kg (P = 0.06), and total insulin dose was reduced by 64% from 33 ± 6 to 11 ± 5 units (P < 0.01). Five out of 10 patients did not require any insulin. C-peptide concentrations increased significantly from 0.43 ± 0.09 ng/ml (0.14 ± 0.02 nmol/L) to 1.42 ± 0.42ng/ml (0.47 ± 0.13 nmol/L) (P = 0.01). Addition of GLP-1RA therapy to insulin in normal-weight patients with T1D led to a reduction in HbA1c with reduced insulin requirements, a 3.5-fold increase in C-peptide concentrations and freedom from insulin therapy in 50% of patients who tolerated the GLP-1RA therapy over a period of 12 ± 1 weeks.

Current Progress in Pharmacogenetics of Second-Line Antidiabetic Medications: Towards Precision Medicine for Type 2 Diabetes

Precision medicine is a scientific and medical practice for personalized therapy based on patients’ individual genetic, environmental, and lifestyle characteristics. Pharmacogenetics and pharmacogenomics are also rapidly developing and expanding as a key element of precision medicine, in which the association between individual genetic variabilities and drug disposition and therapeutic responses are investigated. Type 2 diabetes (T2D) is a chronic metabolic disorder characterized by hyperglycemia mainly associated with insulin resistance, with the risk of clinically important cardiovascular, neurological, and renal complications. The latest consensus report from the American Diabetes Association and European Association for the Study of Diabetes (ADA-EASD) on the management of T2D recommends preferential use of glucagon-like peptide-1 (GLP-1) receptor agonists, sodium-glucose cotransporter-2 (SGLT2) inhibitors, and some dipeptidyl peptidase-4 (DPP-4) inhibitors after initial metformin monotherapy for diabetic patients with established atherosclerotic cardiovascular or chronic kidney disease, and with risk of hypoglycemia or body weight-related problems. In this review article, we summarized current progress on pharmacogenetics of newer second-line antidiabetic medications in clinical practices and discussed their therapeutic implications for precision medicine in T2D management. Several biomarkers associated with drug responses have been identified from extensive clinical pharmacogenetic studies, and functional variations in these genes have been shown to significantly affect drug-related glycemic control, adverse reactions, and risk of diabetic complications. More comprehensive pharmacogenetic research in various clinical settings will clarify the therapeutic implications of these genes, which may be useful tools for precision medicine in the treatment and prevention of T2D and its complications.

Evaluation and management of ketosis-prone diabetes

INTRODUCTION

Patients presenting with diabetic ketoacidosis (DKA) who lack the classic phenotype of autoimmune type 1 diabetes have become increasingly identified in recent decades. This has led to the recognition of heterogeneous syndromes of 'ketosis-prone diabetes' (KPD). Evaluation and optimal management of KPD differs from that of 'typical' type 1 or type 2 diabetes. Awareness of these differences and a systematic approach to diagnosis and treatment can improve glycemic control and prevent both acute and chronic complications of diabetes.

AREAS COVERED

This article reviews the Aß classification scheme ('A' for autoantibody status and 'ß' for beta cell functional reserve) which accurately delineates subgroups of KPD, and addresses the relevance of defining these subgroups for clinical outcomes and long-term insulin dependence. Subsequently, the detailed evaluation and management of KPD patients after their index DKA episode is described.

EXPERT COMMENTARY

Among patients presenting with DKA, it is important to diagnose specific subgroups of KPD and not assume that they represent exclusively patients with autoimmune type 1 diabetes. The Aß classification is an accurate aid to diagnosis, and permits optimal management of the subgroups (e.g., insulin treatment for the ß- subgroups; follow-up testing and a range of treatment options for the ß+ subgroups).

Long circulating genetically encoded intrinsically disordered zwitterionic polypeptides for drug delivery

The clinical utility of many peptide and protein drugs is limited by their short in-vivo half-life. To address this limitation, we report a new class of polypeptide-based materials that have a long plasma circulation time. The design of these polypeptides is motivated by the hypothesis that incorporating a zwitterionic sequence, within an intrinsically disordered polypeptide motif, would impart "stealth" behavior to the polypeptide and increase its plasma residence time, a behavior akin to that of synthetic stealth polymers. We designed these zwitterionic polypeptides (ZIPPs) with a repetitive (VPX₁X₂G)_n motif, where X₁ and X₂ are cationic and anionic amino acids, respectively, and n is the number of repeats. To test this hypothesis, we synthesized a set of ZIPPs with different pairs of cationic and anionic residues with varied chain length. We show that a combination of lysine and glutamic acid in the ZIPP confer superior pharmacokinetics, for both intravenous and subcutaneous administration, compared to uncharged control polypeptides. Finally, to demonstrate their clinical utility, we fused the best performing ZIPP sequence to glucagon-like peptide-1 (GLP1), a peptide drug used for treatment of type-2 diabetes and show that the ZIPP-GLP1 fusion outperforms an uncharged polypeptide of the same molecular weight in a mouse model of type-2 diabetes.

The main participation of the enterohormone GLP-1 after bariatric surgery

BACKGROUND

Numerous hypotheses are called to explain the beneficial effect on glucose metabolism after bariatric surgery. Some authors advocate for the secretion and release of various substances with endocrine functions for the explanation on this event. One of the substances most marked as effector, with contrasting effects but controversial data, is GLP-1.

METHODS

Our study was performed in healthy male Wistar rats, to avoid the absence of confounding factors such as T2DM and obesity. In order to know the adaptation of GLP-1 secretion after surgery 5 groups were designated: two control groups (fasting and surgical stress), and three surgical groups (gastric sleeve, 50% resection of the midgut and the Roux en Y gastric bypass). After three months the GLP-1 synthesis in the different portions of the small intestine and the expression of the membrane receptors in pancreatic islet cells were studied by immunohistochemical techniques.

RESULTS

There was a significant increase in the number of secretory cells in ileum, duodenum and jejunum in mixed (RYGB) and malabsorptive (RI50) surgical groups. An elevation of pancreatic receptors signal was also observed in the same techniques versus controls.

CONCLUSIONS

Our data indicate that intestinal secretion of GLP-1 and its sensitivity to the pancreatic changes were increased like a response of an adaptive effect to the mechanical aggression of the digestive tube and as alteration of nutrient flow after surgery.

Exendin-4 protects INS-1 cells against palmitate-induced apoptosis through the IRE1α-Xbp1 signaling pathway

The anti-apoptotic effect of the incretin analog, exendin-4 (EX-4) on pancreatic β cells is mediated via the activation of protein kinase B (Akt) signaling, and its effect is partly produced through the inhibition of endoplasmic reticulum (ER) stress. However, the molecular mechanisms that underlie the effect of EX-4 on the suppression of ER stress and the upregulation of Akt signaling are poorly understood. Inositol-requiring enzyme 1 (IRE1), a member of the ER-localized transmembrane protein family, activates its downstream transcription factor X-box binding protein 1 (XBP1) to mediate a key part of the cellular unfolded protein response in order to cope with ER stress. Using the clonal rat pancreatic β cell line INS-1, the present study produced an in vitro model of ER stress using palmitate (PA) in order to determine whether the beneficial effect of EX-4 under ER stress was regulated by the IRE1α-Xbp1 signaling pathway. The results demonstrated that the reduction in ER stress and the activation Akt by EX-4 may be associated with the upregulation of IRE1α phosphorylation and the splicing of Xbp1 mRNA, which improved PA-reduced cell viability. This effect was partially abrogated by the knockdown of IRE1α with small interfering RNA. Additionally, cellular IRE1α was phosphorylated by the protein kinase A (PKA) associated with EX-4 and the activation of IRE1α, as IRE1α phosphorylation was attenuated by the inhibition of PKA with its inhibitor. In conclusion, the data identified the IRE1α-Xbp1 signaling pathway as an essential mediator that associates EX-4 with the intracellular mechanism that inhibits ER stress and activates Akt in order to regulate β cell survival. This may provide important evidence for the use of EX-4 in treatments for type 2 diabetes.

The EP3 Receptor/Gz Signaling Axis as a Therapeutic Target for Diabetes and Cardiovascular Disease

Cardiovascular disease is a common co-morbidity found with obesity-linked type 2 diabetes. Current pharmaceuticals for these two diseases treat each of them separately. Yet, diabetes and cardiovascular disease share molecular signaling pathways that are increasingly being understood to contribute to disease pathophysiology, particularly in pre-clinical models. This review will focus on one such signaling pathway: that mediated by the G protein-coupled receptor, Prostaglandin E2 Receptor 3 (EP3), and its associated G protein in the insulin-secreting beta-cell and potentially the platelet, Gz. The EP3/Gz signaling axis may hold promise as a dual target for type 2 diabetes and cardiovascular disease.

Diabetes drugs and the incidence of solid cancers: a survey of the current evidence

INTRODUCTION

The evaluation of the relationship between the use of antidiabetic drug and the occurrence of cancer is extremely challenging, both from the clinical and pharmacoepidemiological standpoint. This narrative review described the current evidence supporting a relationship between the use of antidiabetic drugs and the incidence of solid cancers. Areas covered: Data from pharmacoepidemiological studies on cancer incidence were presented for the main antidiabetic drugs and drug classes, including human insulin and insulin analogues, metformin, sulfonylureas, glinides, alpha-glucosidase inhibitors, thiazolidinediones, incretin mimetics, and sodium glucose co-transporter 2 inhibitors. The relationship between the use of antidiabetics and the incidence of solid cancer was described in strata by any cancer and by organ-specific cancer and by drug and by drug classes. Information supporting biological evidence and putative mechanisms were also provided. Expert opinion: The history of exploration of the relationship between antidiabetic drugs and the risk of solid cancers has showed several issues. Unrecognized biases and misinterpretations of study results have had important consequences that delayed the identification of actual risk and benefits of the use of antidiabetic drugs associated with cancer occurrence or progression. The lesson learned from the past should address the future research in this area, since in the majority of cases findings are controversial and confirmatory studies are warranted.

One-week glucose control via zero-order release kinetics from an injectable depot of glucagon-like peptide-1 fused to a thermosensitive biopolymer

Stimulation of the glucagon-like peptide-1 (GLP1) receptor is a useful treatment strategy for type 2 diabetes because of pleiotropic effects, including the regulation of islet hormones and the induction of satiety. However, the native ligand for the GLP1 receptor has a short half-live owing to enzymatic inactivation and rapid clearance. Here, we show that a subcutaneous depot formed after a single injection of GLP1 recombinantly fused to a thermosensitive elastin-like polypeptide results in zero-order release kinetics and circulation times of up to 10 days in mice and 17 days in monkeys. The optimized pharmacokinetics leads to 10 days of glycemic control in three different mouse models of diabetes, as well as to the reduction of glycosylated hemoglobin levels and weight gain in ob/ob mice treated once weekly for 8 weeks. Our results suggest that the optimized GLP1 formulation could enhance therapeutic outcomes by eliminating peak-and-valley pharmacokinetics and improving overall safety and tolerability. The design principles that we established should be broadly applicable for improving the pharmacological performance of other peptide and protein therapeutics.

Efficacy and Safety of the Dipeptidyl Peptidase-4 Inhibitor Sitagliptin on Atherosclerosis, β-Cell Function, and Glycemic Control in Japanese Patients with Type 2 Diabetes Mellitus Who are Treatment Naïve or Poorly Responsive to Antidiabetes Agents: A Multicenter, Prospective Observational, Uncontrolled Study

BACKGROUND

Sitagliptin, a dipeptidyl peptidase-4 inhibitor, is widely used in patients with type 2 diabetes. However, the pleiotropic effects of sitagliptin is not well understood.

OBJECTIVE

To assess the clinical efficacy and safety of sitagliptin on atherosclerosis, β-cell function, and glycemic control in Japanese patients with type 2 diabetes.

METHODS

A prospective observational study of 270 patients with type 2 diabetes mellitus was carried out. Patients (aged 64.3 [12.4] years, body mas index 25.2 [4.3]) with glycated hemoglobin >6.9% (52 mmol/mol) or fasting plasma glucose >130 mg/dL were treated with sitagliptin for 12 months. The primary end point was glycated hemoglobin level changes from baseline to 3 months. The secondary end points included changes in several biomarkers related to inflammation and β-cell function from baseline to 3 months, as well as changes in glycated hemoglobin level from baseline to 12 months.

RESULTS

Glycated hemoglobin levels were significantly lower in patients treated with sitagliptin for 3 months than at baseline (8.1% [1.4%]-7.3% [1.2%]) (65 [16.9]-56 [13.1] mmol/mol]) (P < 0.0001), which continued after 12 months (7.4% [1.3%]) (56 [15.2] mmol/mol) (P < 0.0001). In addition, a marker of vascular-specific inflammation, pentraxin-3, and a marker of β-cell function (proinsulin/insulin ratio), respectively, were lower after treatment with sitagliptin for 3 months than at baseline (1.88 [0.78]-1.65 [0.63] ng/mL [P = 0.0038] and 0.20 [0.14]-0.17 [0.11] [P = 0.01], respectively). On the other hand, a biomarker reflecting whole body inflammation; that is, high-sensitivity C-reactive protein level, was unchanged. Adverse events occurred in 14 patients (5.18%).

CONCLUSIONS

Sitagliptin may have beneficial effects on vascular inflammation and β-cell function in Japanese patients with type 2 diabetes. Pentraxin-3 may be an early predictive marker for detecting the antiatherosclerotic effects of dipeptidyl peptidase-4.

THE ROLE OF METABOLIC SURGERY FOR PATIENTS WITH OBESITY GRADE I AND TYPE 2 DIABETES NOT CONTROLLED CLINICALLY

Introduction

Even considering the advance of the medical treatment in the last 20 years with new and more effective drugs, the outcomes are still disappointing as the control of obesity and type 2 Diabetes Mellitus (T2DM) with a large number of patients under the medical treatment still not reaching the desired outcomes.

Objective:

To present a Metabolic Risk Score to better guide the surgical indication for T2DM patients with body mass index (BMI) where surgery for obesity is still controversial.

Method:

Research was conducted in Pubmed, Medline, Pubmed Central, Scielo and Lilacs between 2003-2015 correlating headings: metabolic surgery, obesity and type 2 diabetes mellitus. In addition, representatives of the societies involved, as an expert panel, issued opinions.

Results:

Forty-five related articles were analyzed by evidence-based medicine criteria. Grouped opinions sought to answer the following questions: Why metabolic and not bariatric surgery?; Mechanisms involved in glycemic control; BMI as a single criterion for surgical indication for uncontrolled T2DM; Results of metabolic surgery studies in BMI<35 kg/m²; Safety of metabolic surgery in patients with BMI<35 kg/m²; Long-term effects of surgery in patients with baseline BMI<35 kg/m² and Proposal for a Metabolic Risk Score.

Conclusion:

Metabolic surgery has well-defined mechanisms of action both in experimental and human studies. Gastrointestinal interventions in T2DM patients with IMC≤35 kg/m² has similar safety and efficacy when compared to groups with greater BMIs, leading to the improvement of diabetes in a superior manner than clinical treatment and lifestyle changes, in part through weight loss independent mechanisms . There is no correlation between baseline BMI and weight loss in the long term with the success rate after any surgical treatment. Gastrointestinal surgery treatment may be an option for patients with T2DM without adequate clinical control, with a BMI between 30 and 35, after thorough evaluation following the parameters detailed in Metabolic Risk Score defined by the surgical societies. Roux-en-Y gastric bypass (RYGB), because of its well known safety and efficacy and longer follow-up studies, is the main surgical technique indicated for patients eligible for surgery through the Metabolic Risk Score. The vertical sleeve gastrectomy may be considered if there is an absolute contraindication for the RYGB. T2DM patients should be evaluated by the multiprofessional team that will assess surgical eligibility, preoperative work up, follow up and long term monitoring for micro and macrovascular complications.

The Impact of Bariatric Surgery on Type 2 Diabetes Mellitus and the Management of Hypoglycemic Events

Recent studies discussed the benefit of bariatric surgery on obese patients diagnosed with type 2 diabetes mellitus (T2DM). Several factors play an essential role in predicting the impact of bariatric surgery on T2DM, such as ABCD score (age, BMI, C-peptide, and duration of the disease), HbA1c, and fasting blood glucose, incretins [glucagon-like peptide-1 (GLP-1) and gastric inhibitory peptide (GIP)]. DiaRem score known to include factors such as age, HbA1c, medication, and insulin usage used to predict the remission of T2DM, but it has some limitations. An extensive literature search was conducted on PubMed and Google Scholar using keywords such as gastric bypass, T2DM, bariatric surgery, GLP-1, GIP, and post bariatric hypoglycemia. Restrictive-malabsorptive procedures are most effective in treating T2DM patients based on changes induced in appetite through regulation of gastrointestinal hormones, with decreased hunger and increased satiation. We provide a review of bariatric surgery influence on T2DM and management of post-intervention hypoglycemic events. Post-bariatric surgery hypoglycemia is a serious complication especially when patients develop life-threatening neuroglycopenia with loss of consciousness and seizure. The avoidance of this adverse event may be achieved by strict dietary modification including a restriction on carbohydrates as well as foods with high glycemic index. Further research will provide more information on post-bariatric surgery hyperinsulinemic hypoglycemia pathophysiology and management.

Lactobacillus rhamnosus NCDC17 ameliorates type-2 diabetes by improving gut function, oxidative stress and inflammation in high-fat-diet fed and streptozotocintreated rats

Restoration of dysbiosed gut microbiota through probiotic may have profound effect on type 2 diabetes. In the present study, rats were fed high fat diet (HFD) for 3 weeks and injected with low dose streptozotocin to induce type 2 diabetes. Diabetic rats were then fed Lactobacillus rhamnosus NCDC 17 and L. rhamnosus GG with HFD for six weeks. L. rhamnosus NCDC 17 improved oral glucose tolerance test, biochemical parameters (fasting blood glucose, plasma insulin, glycosylated haemoglobin, free fatty acids, triglycerides, total cholesterol, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol), oxidative stress (thiobarbituric acid reactive substance and activities of catalase, superoxide dismutase and glutathione peroxidase in blood and liver), bifidobacteria and lactobacilli in cecum, expression of glucagon like peptide-1 producing genes in cecum, and adiponection in epididymal fat, while decreased propionate proportions (%) in caecum, and expression of tumour necrosis factor-α and interlukin-6 in epididymal fat of diabetic rats as compared to diabetes control group. These findings offered a base for the use of L. rhamnosus NCDC 17 for the improvement and early treatment of type 2 diabetes.

The Development of Diabetes after Subtotal Gastrectomy with Billroth II Anastomosis for Peptic Ulcer Disease

PURPOSE

A duodenal bypass after a Roux-en-Y gastric bypass operation for obesity can ameliorate the development of diabetes mellitus (DM). We attempted to determine the subsequent risk of developing DM after subtotal gastrectomy with Billroth II anastomosis (SGBIIA) for peptic ulcer disease (PUD).

METHODS

We identified 662 patients undergoing SGBIIA for PUD between 2000 and 2011 from the Longitudinal Health Insurance Database as the study cohort, and we randomly selected 2647 controls from the peptic ulcer population not undergoing SGBIIA and were frequency-matched by age, sex, and index year for the control cohort. All patient cases in both cohorts were followed until the end of 2011 to measure the incidence of DM. We analyzed DM risk by using a Cox proportional hazards regression model.

RESULTS

The patients who underwent SGBIIA demonstrated a lower cumulative incidence of DM compared with the control cohort (log-rank test, P < .001 and 6.73 vs 12.6 per 1000 person-y). The difference in the DM risk between patients with and without SGBIIA increased gradually with the follow-up duration. Age and sex did not affect the subsequent risk of developing DM, according to the multivariable Cox regression model. Nevertheless, the SGBIIA cohort exhibited a lower DM risk after we adjusted for the comorbidities of hypertension, hyperlipidemia, and coronary artery disease (adjusted hazard ratio (aHR): 0.56, 95% confidence interval (CI): 0.40-0.78). The incidence rate ratio (IRR) of DM in the SGBIIA cohort was lower than that in the control cohort for all age groups (age ≤ 49 y, IRR: 0.40, 95% CI: 0.16-0.99; age 50-64 y, IRR: 0.54, 95% CI: 0.31-0.96; age ≧ 65 y, IRR: 0.57, 95% CI: 0.36-0.91). Moreover, the IRR of DM was significantly lower in the SGBIIA cohort with comorbidities (IRR: 0.50, 95% CI: 0.31-0.78) compared with those without a comorbidity (IRR: 0.65, 95% CI: 0.40-1.04).

CONCLUSION

The findings of this population-based cohort study revealed that SGBIIA was associated with a reduced risk of DM development, and the inverse association was greater in the presence of a comorbidity.

Comparison of Regulation Mechanisms of Five Mulberry Ingredients on Insulin Secretion under Oxidative Stress

The effects of mulberry ingredients including 1-deoxynojrimycin (DNJ), resveratrol (RES), oxyresveratrol (OXY), cyanidin-3-glucoside (C3G), and cyanidin-3-rutinoside (C3R) on insulin secretion under oxidative stress were investigated. The results revealed that they had distinct effects on insulin secretion in H₂O₂-induced MIN 6 cells, especially DNJ, C3G, and C3R, while RES and OXY showed modest effects in low dose (12.5 μM). The mechanisms were demonstrated in signal pathway that after treatment with DNJ, C3G, and C3R, the expressions of glucokinase (GK) were up-regulated, leading to intracellular ATP accumulation and insulin secretion. They also bound to glucagon-like peptide-1 receptor (GLP-1R), improved GLP-1R, duodenal homeobox factor-1 (PDX-1) expression, and stimulated insulin secretion. Moreover, ROS production was inhibited, followed by a decreasing apoptosis rate, while RES and OXY accelerated the apoptosis at high dose (50 μM). This work expounded the potential mechanisms of mulberry ingredients on insulin secretion, indicating the potential application in the intervention against hyperglycemia.

Combination therapy of SGLT2 inhibitors with incretin-based therapies for the treatment of type 2 diabetes mellitus: Effects and mechanisms of action

Type 2 diabetes mellitus (T2DM) is a growing health problem worldwide; its pathogenesis is multifactorial and its progressive nature often necessitates a combination therapy with multiple antihyperglycemic agents. Sodium glucose cotransporter 2 (SGLT2) inhibitors and the incretin-based therapies - dipeptidyl peptidase 4(DPP-4) inhibitors and glucagon-like peptide 1 (GLP-1) receptor agonists - were introduced for the treatment of T2DM within the last decade. Evidence of the beneficial effects of these antihyperglycemic agents on micro- and macrovascular complications have started to emerge, which will become important in individualizing different combinations of antihyperglycemic agents to different patient populations. We review here the mechanisms of action, glycemic and cardiovascular effects of SGLT2 inhibitors and incretin-based therapies and their combination in the treatment of T2DM.

Subtotal Gastrectomy With Billroth II Anastomosis Is Associated With a Low Risk of Ischemic Stroke in Peptic Ulcer Disease Patients: A Nationwide Population-Based Study

Duodenal diversion can ameliorate lipid and glucose metabolism. We assessed the risk of stroke after subtotal gastrectomy with Billroth II anastomosis (SGBIIA) in peptic ulcer disease (PUD). We identified 6425 patients who received SGBIIA for PUD between 1998 and 2010 from the Taiwan National Health Insurance Research Database as the study cohort; we frequency-matched them with 25,602 randomly selected controls from the PUD population who did not receive SGBIIA according to age, sex, index year, and comorbidities including hypertension, diabetes mellitus, hyperlipidemia, coronary artery disease, congestive heart failure, chronic kidney disease, chronic obstructive pulmonary disease (COPD), and obesity. All patients were followed until the end of 2011 to determine the incidence of stroke. The incidence of stroke was lower in patients in the SGBIIA cohort than in those in the non-SGBIIA cohort (18.9 vs 22.9 per 1000 person-years, adjusted hazard ratio [aHR] 0.80, 95% confidence interval [CI] 0.72-0.89, P < 0.001). The risk of ischemic stroke (aHR 0.77, 95% CI 0.69-0.86, P < 0.001), rather than hemorrhagic stroke (aHR 1.00, 95% CI 0.78-1.28), was lower for the SGBIIA cohort than for the non-SGBIIA cohort according to the multivariable Cox proportional hazard regression analysis. The relative risk of ischemic stroke after SGBIIA was lower in men (aHR 0.77, 95% CI 0.69-0.86) than in women (aHR 0.80, 95% CI 0.65-0.99) and in patients aged ≥65 years (aHR 0.72, 95% CI 0.63-0.81) than in those of other age groups (≤49 years, aHR 0.82, 95% CI 0.48-1.39; 50-64 years, aHR 1.01, 95% CI 0.79-1.28). The relative risk of ischemic stroke after SGBIIA was also reduced in patients with comorbidities (aHR 0.84, 5% CI 0.75-0.95) rather than in those without comorbidities (aHR 0.81, 95% CI 0.59-1.12). SGBIIA is associated with a low risk of ischemic stroke for PUD patients, and its protective effect is prominent in men, patients aged ≥65 years, and those with comorbidities.

Antihyperglycemic and Antiobesity Effects of JAL2 on db/db Mice

Lonicera japonica Thunb. (LJT) and Rehmannia glutinosa Libosch. (RGL) have been used traditionally as a herbal medicine in Korean medicine. Using LC/Q-TOF was performed to profile the two herbal medicines and the mixture of LJR and RGL (JAL2, ratio 1 : 1). We performed oral glucose tolerance test (OGTT) and plasma GLP-1 and insulin secretion by multiplex assays to investigate antidiabetic effects of LJT, RGL, and JAL2 in db/db mice, the mice model of type 2 diabetes mellitus (T2DM). Also, the antiobesity-related factors such as plasma peptide YY (PYY), triglyceride, total cholesterol, HDL, LDL, and weight of liver, epididymal, and retroperitoneal fat tissue were investigated. Through the multiplex assay, it was found that JAL2 treatment more efficiently attenuated high levels of blood glucose by stimulating GLP-1 secretion and reduced LDL concentration and weight of liver and retroperitoneal fat tissue compared to LJT or RGL treated separately. These results suggest that the JAL2 has antidiabetes and antiobesity effects in T2DM mice model.

Protective Effects of Glucagon-like Peptide 1 on Endothelial Function in Hypertension

Vascular endothelial cells play a major role in maintaining cardiovascular homeostasis. Endothelial dysfunction, characterized by reduced endothelium-dependent relaxations or accompanied by enhanced endothelium-dependent contractions, is a hallmark of and plays a pivotal role in the pathogenesis of hypertension. Endothelial dysfunction in hypertension has been linked to decreases in nitric oxide (NO) bioavailability, reflecting the impaired generation of NO and/or the enhanced inactivation of NO by reactive oxygen species. Many of these conditions can be improved by glucagon-like peptide 1 (GLP-1), a proglucagon-derived hormone secreted by intestinal endocrine L-type cells, which is rapidly inactivated by an enzyme dipeptidyl peptidase 4 in circulation. On one hand, GLP-1 analogues or dipeptidyl peptidase 4 inhibitors upregulate endothelial nitric oxide synthase expression and increase endothelial nitric oxide synthase phosphorylation, resulting in improved production of NO and thus endothelium-dependent relaxations. On the other hand, GLP-1 and related agents attenuate endothelium-dependent contractions by reducing reactive oxygen species generation and cyclooxygenase-2 expression. GLP-1 elevating agents and GLP-1 receptor agonists improve endothelial function in hypertension, suggesting that GLP-1 signaling could be a therapeutic target in hypertension-related vascular events.