Cardiovascular effects of glucagon-like peptide 1 (GLP-1) receptor agonists

Lipid profile changes induced by glucagon-like peptide-1 receptor agonists in patients with type 2 diabetes: a systematic review and network meta-analysis

OBJECTIVE

This study was conducted to investigate the effects of glucagon-like peptide-1 receptor (GLP-1) agonists on the lipid profiles of patients with type 2 diabetes.

METHODS

We retrieved the data of phase 3 randomized controlled trials on GLP-1 agonists in patients with type 2 diabetes from the PubMed, Embase, and Cochrane library up to 11 February 2024. We extracted % changes in low-density lipoprotein cholesterol (LDL-C)/high-density lipoprotein cholesterol/total cholesterol (T-CHO) and triglycerides levels from baseline. Using Bayesian network meta-analysis, mean differences and 95% credible intervals for lipid changes were estimated as a unit of percentage points (%p) by class.

RESULTS

Twenty-six studies covering 22,290 participants were included. The glucose-dependent insulinotropic polypeptide (GIP)/GLP-1 dual agonist showed significant differences in LDL-C (range of mean differences: -11.61 to -6.77%p), triglycerides (-19.94 to -13.31%p), and T-CHO (-7.94 to -5.09%p) levels compared to placebo, insulin, and sodium-glucose co-transporter 2 (SGLT2) inhibitors. The GLP-1 agonist significantly reduced T-CHO (-5.20%p; -6.39%p) and LDL-C (-4.32%p; -8.17%p) levels compared to placebo and SGLT2 inhibitors, respectively.

CONCLUSIONS

The GIP/GLP-1 dual agonist positively affects the lipid profiles of patients with type 2 diabetes. This may contribute to a lower risk of cardiovascular disease in patients with type 2 diabetes.

PROTOCOL REGISTRATION

PROSPERO (CRD42021282668).

A comprehensive in-vitro/in-vivo screening toolbox for the elucidation of glucose homeostasis modulating properties of plant extracts (from roots) and its bioactives

Plant extracts are increasingly recognized for their potential in modulating (postprandial) blood glucose levels. In this context, root extracts are of particular interest due to their high concentrations and often unique spectrum of plant bioactives. To identify new plant species with potential glucose-lowering activity, simple and robust methodologies are often required. For this narrative review, literature was sourced from scientific databases (primarily PubMed) in the period from June 2022 to January 2024. The regulatory targets of glucose homeostasis that could be modulated by bioactive plant compounds were used as search terms, either alone or in combination with the keyword "root extract". As a result, we present a comprehensive methodological toolbox for studying the glucose homeostasis modulating properties of plant extracts and its constituents. The described assays encompass in-vitro investigations involving enzyme inhibition (α-amylase, α-glucosidase, dipeptidyl peptidase 4), assessment of sodium-dependent glucose transporter 1 activity, and evaluation of glucose transporter 4 translocation. Furthermore, we describe a patch-clamp technique to assess the impact of extracts on KATP channels. While validating in-vitro findings in living organisms is imperative, we introduce two screenable in-vivo models (the hen's egg test and Drosophila melanogaster). Given that evaluation of the bioactivity of plant extracts in rodents and humans represents the current gold standard, we include approaches addressing this aspect. In summary, this review offers a systematic guide for screening plant extracts regarding their influence on key regulatory elements of glucose homeostasis, culminating in the assessment of their potential efficacy in-vivo. Moreover, application of the presented toolbox might contribute to further close the knowledge gap on the precise mechanisms of action of plant-derived compounds.

The impact of GLP-1 receptor agonist liraglutide on blood pressure profile, hydration, natriuresis in diabetic patients with severely impaired kidney function

Chronic treatment with GLP-1R agonists may moderately lower blood pressure due to increased natriuresis and RAAS inhibition. Short-term effect of these drugs on blood pressure may be opposite and its mechanism remains unclear. We investigated the effect of a single dose of liraglutide on diurnal blood pressure profile, natriuresis, hydration and serum concentration of renin, aldosterone and atrial natriuretic peptide (ANP) in diabetic kidney disease (DKD). 17 patients with eGFR < 30 ml/min/1.73 m2 and 17 with > 60 ml/min/1.73 m2 received in a random order a single subcutaneous dose 1.2 mg liraglutide and placebo with subsequent 24 h blood pressure and natriuresis monitoring. Before and after each medication thoracic fluid index and plasma renin, aldosterone and ANP were also assessed. The blood pressure load in the daytime and nighttime were significantly increased after liraglutide compared to placebo in patients with eGFR < 30 ml/min/1.73 m2. In patients with eGFR > 60 ml/min/1.73 m2 the changes of arterial pressure were comparable, while the morning surge was significantly reduced after liraglutide compared to placebo. After liraglutide 24 h urine sodium excretion increased in both groups vs. placebo (p < 0.001), the effect was greatest in subjects with eGFR > 60 ml/min/1.73 m2. Plasma ANP increased after liraglutide in both groups, most in patients with eGFR < 30 ml/min/1.73 m2 group. Plasma aldosterone (p = 0.013) and thoracic fluid index (p = 0.01) decreased after liraglutide compared to placebo (p = 0.013 and p + 0.01, respectively. Plasma renin concentration remained unchanged. In severe chronic kidney disease liraglutide induces a transient increase of blood pressure due to reduced natriuresis. The natriuretic effect of liraglutide in DKD may be related to increased ANP and decreased aldosterone secretion.

Glucagon-Like Peptide Receptor Agonist Inhibits Angiotensin II-Induced Proliferation and Migration in Vascular Smooth Muscle Cells and Ameliorates Phosphate-Induced Vascular Smooth Muscle Cells Calcification

BACKGRUOUND

Glucagon-like peptide-1 receptor agonist (GLP-1RA), which is a therapeutic agent for the treatment of type 2 diabetes mellitus, has a beneficial effect on the cardiovascular system.

METHODS

To examine the protective effects of GLP-1RAs on proliferation and migration of vascular smooth muscle cells (VSMCs), A-10 cells exposed to angiotensin II (Ang II) were treated with either exendin-4, liraglutide, or dulaglutide. To examine the effects of GLP-1RAs on vascular calcification, cells exposed to high concentration of inorganic phosphate (Pi) were treated with exendin-4, liraglutide, or dulaglutide.

RESULTS

Ang II increased proliferation and migration of VSMCs, gene expression levels of Ang II receptors AT1 and AT2, proliferation marker of proliferation Ki-67 (Mki-67), proliferating cell nuclear antigen (Pcna), and cyclin D1 (Ccnd1), and the protein expression levels of phospho-extracellular signal-regulated kinase (p-Erk), phospho-c-JUN N-terminal kinase (p-JNK), and phospho-phosphatidylinositol 3-kinase (p-Pi3k). Exendin-4, liraglutide, and dulaglutide significantly decreased the proliferation and migration of VSMCs, the gene expression levels of Pcna, and the protein expression levels of p-Erk and p-JNK in the Ang II-treated VSMCs. Erk inhibitor PD98059 and JNK inhibitor SP600125 decreased the protein expression levels of Pcna and Ccnd1 and proliferation of VSMCs. Inhibition of GLP-1R by siRNA reversed the reduction of the protein expression levels of p-Erk and p-JNK by exendin-4, liraglutide, and dulaglutide in the Ang II-treated VSMCs. Moreover, GLP-1 (9-36) amide also decreased the proliferation and migration of the Ang II-treated VSMCs. In addition, these GLP-1RAs decreased calcium deposition by inhibiting activating transcription factor 4 (Atf4) in Pi-treated VSMCs.

CONCLUSION

These data show that GLP-1RAs ameliorate aberrant proliferation and migration in VSMCs through both GLP-1Rdependent and independent pathways and inhibit Pi-induced vascular calcification.

Pharmacological modulation of vascular ageing: A review from VascAgeNet

Vascular ageing, characterized by structural and functional changes in blood vessels of which arterial stiffness and endothelial dysfunction are key components, is associated with increased risk of cardiovascular and other age-related diseases. As the global population continues to age, understanding the underlying mechanisms and developing effective therapeutic interventions to mitigate vascular ageing becomes crucial for improving cardiovascular health outcomes. Therefore, this review provides an overview of the current knowledge on pharmacological modulation of vascular ageing, highlighting key strategies and promising therapeutic targets. Several molecular pathways have been identified as central players in vascular ageing, including oxidative stress and inflammation, the renin-angiotensin-aldosterone system, cellular senescence, macroautophagy, extracellular matrix remodelling, calcification, and gasotransmitter-related signalling. Pharmacological and dietary interventions targeting these pathways have shown potential in ameliorating age-related vascular changes. Nevertheless, the development and application of drugs targeting vascular ageing is complicated by various inherent challenges and limitations, such as certain preclinical methodological considerations, interactions with exercise training and sex/gender-related differences, which should be taken into account. Overall, pharmacological modulation of endothelial dysfunction and arterial stiffness as hallmarks of vascular ageing, holds great promise for improving cardiovascular health in the ageing population. Nonetheless, further research is needed to fully elucidate the underlying mechanisms and optimize the efficacy and safety of these interventions for clinical translation.

Comparative effectiveness of SGLT2 inhibitors, GLP-1 receptor agonists, DPP-4 inhibitors, and sulfonylureas on risk of major adverse cardiovascular events: emulation of a randomised target trial using electronic health records

BACKGROUND

Randomised clinical trials showed that compared with placebo, SGLT2 inhibitors and GLP-1 receptor agonists reduced risk of adverse cardiovascular events. The evidence base for the older antihyperglycaemic drug classes (DPP-4 inhibitors and sulfonylureas) is generally less well developed. Because most randomised trials evaluated one antihyperglycaemic medication versus placebo, a head-to-head comparative effectiveness analysis of the newer drug classes (SGLT2 inhibitors vs GLP-1 receptor agonists) or newer (SGLT2 inhibitors or GLP-1 receptor agonists) versus older (DPP-4 inhibitors or sulfonylureas) drug classes on risk of major adverse cardiovascular events (MACE) is not available. In this study, we aimed to evaluate the comparative effectiveness of incident use of SGLT2 inhibitors, GLP-1 receptor agonists, DPP-4 inhibitors, or sulfonylureas on risk of MACE.

METHODS

We first specified the protocol of a four-arm randomised pragmatic clinical trial and then emulated it using the health-care databases of the US Department of Veterans Affairs. We built a cohort of metformin users with incident use of SGLT2 inhibitors, GLP-1 receptor agonists, DPP-4 inhibitors, or sulfonylureas between Oct 1, 2016 and Sept 30, 2021, and followed up until Dec 31, 2022. We used the overlap weighting approach to balance the treatment groups using a battery of predefined variables and a set of algorithmically selected variables from high-dimensional data domains. Both intention-to-treat and per-protocol analyses (the latter estimated the effect of maintained use of the antihyperglycaemic throughout follow-up) were conducted to estimate risk of MACE-defined as a composite endpoint of stroke, myocardial infarction, and all-cause mortality.

FINDINGS

The final cohort consisted of 283 998 new users of SGLT2 inhibitors (n=46 516), GLP-1 receptor agonists (n=26 038), DPP-4 inhibitors (n=55 310), or sulfonylureas (n=156 134). In intention-to-treat analyses, compared with sulfonylureas, SGLT2 inhibitors, GLP-1 receptor agonists, and DPP-4 inhibitors were associated with lower risk of MACE (hazard ratio [HR] 0·77 [95% CI 0·74-0.80], 0·78 [0·74-0·81), and 0·90 [0·86-0.93], respectively). Both SGLT2 inhibitors and GLP-1 receptor agonists were associated with a lower risk of MACE when compared with DPP-4 inhibitors (HR 0·86 [0·82-0·89] and 0·86 [0·82-0·90], respectively). The risk of MACE between SGLT2 inhibitors and GLP-1 receptor agonists yielded an HR of 0·99 (0·94-1·04). In per-protocol analyses, compared with sulfonylureas, SGLT2 inhibitors, GLP1 receptor agonists, and DPP-4 inhibitors were associated with reduced risk of MACE (HR 0·77 [95% CI 0·73-0·82], 0·77 [0·72-0·82], and 0·88 [0·83-0·93], respectively). Both SGLT2 inhibitors and GLP-1 receptor agonists were associated with a lower risk of MACE when compared with DPP-4 inhibitors (HR 0·88 [0·83-0·93] and 0·88 [0·82-0·93], respectively). The risk of MACE between SGLT2 inhibitors and GLP-1 receptor agonists yielded an HR of 1·01 (0·94-1·07).

INTERPRETATION

Both SGLT2 inhibitors and GLP-1 receptor agonists were associated with reduced risk of MACE compared with DPP-4 inhibitors or sulfonylureas. DPP-4 inhibitors were associated with reduced risk of MACE compared with sulfonylureas. There was no statistically significant difference in risk of MACE between SGLT2 inhibitors and GLP-1 receptor agonists. The results provide evidence of the real-world comparative effectiveness of the four most commonly used second-line antihyperglycaemics and could guide choice of antihyperglycaemic therapy.

FUNDING

US Department of Veterans Affairs and the American Society of Nephrology.

Role of the protein kinase A signaling pathway and identification of mediators in the cardioprotective effects of enteral lactoferrin for ischemia-reperfusion injury in an isolated rat heart model

OBJECTIVE

Lactoferrin is an iron-binding glycoprotein. Enteral lactoferrin attenuates myocardial ischemia-reperfusion (IR) injury, but the underlying mechanism remains unknown. The aim of this study was to investigate protein kinase A (PKA) signaling pathway activation and levels of serum glucagonlike peptide-1 (GLP-1), secreted by intestinal endocrine L cells, and adiponectin, secreted by adipose tissue, after enteral lactoferrin administration.

METHODS

Hearts (N = 32) were excised from Wistar rats and perfused using a Langendorff system. To assess the role of the PKA pathway in the cardioprotective effects of lactoferrin, an inhibitor of PKA (H89) was applied before no-flow ischemia. Rats were randomly divided into four groups: control, lactoferrin (LF), control+H89, and LF+H89. The control and control+H89 groups were administered normal saline by gavage, and the LF and L +H89 groups were administered bovine lactoferrin (1000 mg/kg) by gavage 15 min before intraperitoneal pentobarbital injection. Muscle sampling was performed at the end of reperfusion. When rats were sacrificed, blood was sampled to measure hormone levels. The primary outcome was maximum left ventricular pressure derivative (LV dP/dt max) 15 min after reperfusion.

RESULTS

LV dP/dt max at 10 and 15 min after reperfusion was significantly higher in the LF group than in the control group (P < 0.05), and the effect was diminished by H89. The PKA pathway was significantly activated in the LF group. Enteral lactoferrin increased serum GLP-1 but not serum adiponectin levels.

CONCLUSIONS

Enteral lactoferrin induces cardioprotective effects against myocardial IR injury via the PKA signaling pathway and increases serum GLP-1 levels.

Treatment of HFpEF beyond the SGLT2-Is: Does the Addition of GLP-1 RA Improve Cardiometabolic Risk and Outcomes in Diabetic Patients?

Heart failure with preserved ejection fraction (HFpEF) is a common clinical syndrome frequently seen in elderly patients, the incidence of which is steadily increasing due to an ageing population and the increasing incidence of diseases, such as diabetes, hypertension, obesity, chronic renal failure, and so on. It is a multifactorial disease with different phenotypic aspects that share left ventricular diastolic dysfunction, and is the cause of about 50% of hospitalizations for heart failure in the Western world. Due to the complexity of the disease, no specific therapies have been identified for a long time. Sodium-Glucose Co-Transporter 2 Inhibitors (SGLT2-Is) and Glucagon-Like Peptide Receptor Agonists (GLP-1 RAs) are antidiabetic drugs that have been shown to positively affect heart and kidney diseases. For SGLT2-Is, there are precise data on their potential benefits in heart failure with reduced ejection fraction (HFrEF) as well as in HFpEF; however, insufficient evidence is available for GLP-1 RAs. This review addresses the current knowledge on the cardiac effects and potential benefits of combined therapy with SGLT2-Is and GLP-1RAs in patients with HFpEF.

Liraglutide increases islet Ca2+ oscillation frequency and insulin secretion by activating hyperpolarization-activated cyclic nucleotide-gated channels

AIM

To determine whether hyperpolarization-activated cyclic nucleotide-gated (HCN) channels impact glucagon-like peptide-1 (GLP-1) receptor (GLP-1R) modulation of islet Ca²⁺ handling and insulin secretion.

METHODS

The impact of liraglutide (GLP-1 analogue) on islet Ca²⁺ handling, HCN currents and insulin secretion was monitored with fluorescence microscopy, electrophysiology and enzyme immunoassays, respectively. Furthermore, liraglutide-mediated β-to-δ-cell cross-communication was assessed following selective ablation of either mouse islet δ or β cells.

RESULTS

Liraglutide increased β-cell Ca²⁺ oscillation frequency in mouse and human islets under stimulatory glucose conditions. This was dependent in part on liraglutide activation of HCN channels, which also enhanced insulin secretion. Similarly, liraglutide activation of HCN channels also increased β-cell Ca²⁺ oscillation frequency in islets from rodents exposed to a diabetogenic diet. Interestingly, liraglutide accelerated Ca²⁺ oscillations in a majority of islet δ cells, which showed synchronized Ca²⁺ oscillations equivalent to β cells; therefore, we assessed if either cell type was driving this liraglutide-mediated islet Ca²⁺ response. Although δ-cell loss did not impact liraglutide-mediated increase in β-cell Ca²⁺ oscillation frequency, β-cell ablation attenuated liraglutide-facilitated acceleration of δ-cell Ca²⁺ oscillations.

CONCLUSION

The data presented here show that liraglutide-induced stimulation of islet HCN channels augments Ca²⁺ oscillation frequency. As insulin secretion oscillates with β-cell Ca²⁺ , these findings have important implications for pulsatile insulin secretion that is probably enhanced by liraglutide activation of HCN channels and therapeutics that target GLP-1Rs for treating diabetes. Furthermore, these studies suggest that liraglutide as well as GLP-1-based therapies enhance δ-cell Ca²⁺ oscillation frequency and somatostatin secretion kinetics in a β-cell-dependent manner.

Lipid oxidation in pathophysiology of atherosclerosis: Current understanding and therapeutic strategies

A marked increase in the global prevalence of ischemic heart disease demands focused research for novel and more effective therapeutic strategies. At present, atherosclerotic cardiovascular disease (ACVD) is the leading cause of the global incidence of heart attacks and a major contributor to many peripheral cardiac diseases. Decades of research have unearthed the complex and multidimensional pathophysiology of ACVD encompassing oxidative stress, redox imbalance, lipid peroxidation, pro-inflammatory signaling, hyperglycemic stress and diabetes mellitus, chronic low-grade inflammation and aging, immune dysregulation, vascular dysfunction, loss of hemostasis, thrombosis, and fluid shear stress. However, the scientific basis of therapeutic interventions using conventional understandings of the disease mechanisms has been subject to renewed scrutiny with novel findings in recent years. This critical review attempts to revise the pathophysiological mechanisms of atherosclerosis using a recent body of literature, with a focus on lipid metabolism and associated cellular and biochemical processes. The comprehensive study encompasses different molecular perspectives in the development and progression of coronary atherosclerosis. The review also summarizes currently prescribed small molecule therapeutics in inflammation and ACVD, and overviews prospective management measures under development including peptides and microRNA therapeutics. The study provides updated insights into the current knowledge of coronary atherosclerosis, and highlights the need for effective prevention, management and development of novel intervention approaches to overcome this chronic epidemic.

DPP-4 inhibitors and GLP-1RAs: cardiovascular safety and benefits

Glucagon-like peptide-1 receptor agonists and dipeptidyl peptidase-4 inhibitors are commonly used treatments for patients with type 2 diabetes mellitus (T2DM). Both anti-diabetic treatments function by playing key modulatory roles in the incretin system. Though these drugs have been deemed effective in treating T2DM, the Food and Drug Administration (FDA) and some members of the scientific community have questioned the safety of these therapeutics relative to important cardiovascular endpoints. As a result, since 2008, the FDA has required all new drugs for glycemic control in T2DM patients to demonstrate cardiovascular safety. The present review article strives to assess the safety and benefits of incretin-based therapy, a new class of antidiabetic drug, on the health of patient cardiovascular systems. In the process, this review will also provide a physiological overview of the incretin system and how key components function in T2DM.

Structural basis of peptidomimetic agonism revealed by small- molecule GLP-1R agonists Boc5 and WB4-24

Glucagon-like peptide-1 receptor (GLP-1R) agonists are efficacious in the treatment of type 2 diabetes and obesity. While most clinically used agents require subcutaneous injection, Boc5, as the first orthosteric nonpeptidic agonist of GLP-1R, suffers from poor oral bioavailability that hinders its therapeutic development. The cryoelectron microscopy structures of Boc5 and its closely related analog WB4-24 presented here reveal a binding pocket located deeper in the transmembrane domain for nonpeptidic GLP-1R agonists. Molecular interaction with this site may facilitate a broad spectrum of in vivo agonistic activities, in addition to that with the upper helical bundles presumably responsible for biased signaling. These findings deepen our understanding of peptidomimetic agonism at GLP-1R and may help design better drug leads against this important target.

Glucagon-like peptide-1 receptor (GLP-1R) agonists are effective in treating type 2 diabetes and obesity with proven cardiovascular benefits. However, most of these agonists are peptides and require subcutaneous injection except for orally available semaglutide. Boc5 was identified as the first orthosteric nonpeptidic agonist of GLP-1R that mimics a broad spectrum of bioactivities of GLP-1 in vitro and in vivo. Here, we report the cryoelectron microscopy structures of Boc5 and its analog WB4-24 in complex with the human GLP-1R and G_s protein. Bound to the extracellular domain, extracellular loop 2, and transmembrane (TM) helices 1, 2, 3, and 7, one arm of both compounds was inserted deeply into the bottom of the orthosteric binding pocket that is usually accessible by peptidic agonists, thereby partially overlapping with the residues A8 to D15 in GLP-1. The other three arms, meanwhile, extended to the TM1-TM7, TM1-TM2, and TM2-TM3 clefts, showing an interaction feature substantially similar to the previously known small-molecule agonist LY3502970. Such a unique binding mode creates a distinct conformation that confers both peptidomimetic agonism and biased signaling induced by nonpeptidic modulators at GLP-1R. Further, the conformational difference between Boc5 and WB4-24, two closed related compounds, provides a structural framework for fine-tuning of pharmacological efficacy in the development of future small-molecule therapeutics targeting GLP-1R.

A Glucagon-like Peptide 1 Analog Protects Mitochondria and Attenuates Hypoxia-Reoxygenation Injury in Cultured Cardiomyocytes

ABSTRACT

Glucagon-like peptide 1 (GLP-1) analogs improve glycemic control in diabetes and protect the heart against ischemia-reperfusion injury. However, the mechanisms underlying this protection remain unclear. Mitochondria are essential for myocyte homeostasis. Therefore, we herein examined the effects of a GLP-1 analog on mitochondria after the hypoxia-reoxygenation of rat neonatal cultured cardiomyocytes. Cardiomyocytes were subjected to hypoxia for 5 hours followed by reoxygenation for 30 minutes in the presence or absence of exendin-4 (50 nmol/L), a GLP-1 analog. Hypoxia-reoxygenation increased lactate dehydrogenase and caspase-3 activities, indicators of lethal myocyte injury and apoptosis, respectively, and exendin-4 attenuated these increases. The content of ATP in myocytes decreased after hypoxia-reoxygenation but was preserved by exendin-4. The membrane potential and shape of mitochondria were assessed using a fluorescent probe. Exendin-4 attenuated the hypoxia-reoxygenation-induced disruption of the mitochondrial membrane potential and shortening. Mitochondrial quality control-related factors, such as optic atrophy protein 1, mitofusin 2, dynamin-related protein 1, and parkin, were examined by Western blotting. Exendin-4 significantly increased the expression of the fusion proteins, optic atrophy protein 1 and mitofusin 2, and decreased that of the mitophagy-related protein, parkin, without altering dynamin-related protein 1 expression levels. Exendin-4 also preserved Akt phosphorylation levels after hypoxia-reoxygenation, whereas wortmannin, an inhibitor of the phosphoinositide 3-kinase-Akt pathway, blunted exendin-4-induced myocyte protection and its effects on mitochondrial quality control factors. In conclusion, exendin-4 protected mitochondria by preserving the phosphorylation of Akt and fusion proteins, leading to the attenuation of hypoxia-reoxygenation-induced injury in cultured myocytes.

Anti-inflammatory effects of GLP-1 in patients with COVID-19

INTRODUCTION

Understanding the pathogenesis and risk factors to control the coronavirus disease 2019 (COVID-19) is necessary. Due to the importance of the inflammatory pathways in the pathogenesis of COVID-19 patients, evaluating the effects of anti-inflammatory medications is important. Glucagon-like peptide 1 receptor agonist (GLP-1 RA) is awell-known glucose-lowering agent with anti-inflammatory effects.

AREAS COVERED

Resources were extracted from the PubMed database, using keywords such as glucagon-like peptide-1, GLP-1 RA, SARS-CoV-2, COVID-19, inflammation, in April2021. In this review, the effects of GLP-1RA in reducing inflammation and modifying risk factors of COVID-19 severe complications are discussed. However, GLP-1 is degraded by DPP-4 with aplasma half-life of about 2-5 minutes, which makes it difficult to measure GLP-1 plasma level in clinical settings.

EXPERT OPINION

Since no definitive treatment is available for COVID-19 so far, determining promising targets to design and/or repurpose effective medications is necessary.

A Review of Oral Semaglutide Available Evidence: A New Era of Management of Diabetes with Peptide in a Pill Form

Glucagon-like peptide 1 receptor agonists (GLP-1RAs) have gained an important place in the management of diabetes management because of their exceptional glucose-lowering, weight lowering and cardiovascular (CV) benefits. Despite recommendations by various clinical practice guidelines and benefits, their usage in clinical practice was limited because of being injectable in nature. Oral semaglutide is a novel GLP-1RA with 94% homology to human GLP-1 which is co-formulated with absorption enhancer sodium N-(8-[2-hydroxybenzoyl] amino) caprylate (SNAC), that overcomes the challenges of peptide absorption in the acidic conditions of the stomach. Oral semaglutide has been evaluated in an extensive phase 3 clinical trial programme named Peptide Innovation for Early Diabetes Treatment (PIONEER) which demonstrated its robust glucose and weight lowering effects against other comparators. The evolution of the GLP-1RA class to include an oral pill will facilitate the use of this class of agents much earlier in the diabetes treatment cascade owing to wider acceptance from patients and clinicians alike. The current review discusses the various aspects of oral semaglutide and its place in clinical practice.

Luseogliflozin, a sodium-glucose cotransporter-2 inhibitor, reverses cerebrovascular dysfunction and cognitive impairments in 18-mo-old diabetic animals

Diabetes mellitus (DM) is a leading risk factor for age-related dementia, but the mechanisms involved are not well understood. We previously discovered that hyperglycemia induced impaired myogenic response (MR) and cerebral blood flow (CBF) autoregulation in 18-mo-old DM rats associated with blood-brain barrier (BBB) leakage, impaired neurovascular coupling, and cognitive impairment. In the present study, we examined whether reducing plasma glucose with a sodium-glucose cotransporter-2 inhibitor (SGLT2i) luseogliflozin can ameliorate cerebral vascular and cognitive function in diabetic rats. Plasma glucose and HbA1c levels of 18-mo-old DM rats were reduced, and blood pressure was not altered after treatment with luseogliflozin. SGLT2i treatment restored the impaired MR of middle cerebral arteries (MCAs) and parenchymal arterioles and surface and deep cortical CBF autoregulation in DM rats. Luseogliflozin treatment also rescued neurovascular uncoupling, reduced BBB leakage and cognitive deficits in DM rats. However, SGLT2i did not have direct constrictive effects on vascular smooth muscle cells and MCAs isolated from normal rats, although it decreased reactive oxygen species production in cerebral vessels of DM rats. These results provide evidence that normalization of hyperglycemia with an SGLT2i can reverse cerebrovascular dysfunction and cognitive impairments in rats with long-standing hyperglycemia, possibly by ameliorating oxidative stress-caused vascular damage.NEW & NOTEWORTHY This study demonstrates that luseogliflozin, a sodium-glucose cotransporter-2 inhibitor, improved CBF autoregulation in association with reduced vascular oxidative stress and AGEs production in the cerebrovasculature of 18-mo-old DM rats. SGLT2i also prevented BBB leakage, impaired functional hyperemia, neurodegeneration, and cognitive impairment seen in DM rats. Luseogliflozin did not have direct constrictive effects on VSMCs and MCAs isolated from normal rats. These results provide evidence that normalization of hyperglycemia with an SGLT2i can reverse cerebrovascular dysfunction and cognitive impairments in rats with long-standing hyperglycemia, possibly by ameliorating oxidative stress-caused vascular damage.

Imaging techniques for the assessment of adverse cardiac remodeling in metabolic syndrome

Metabolic syndrome (MetS) includes different metabolic conditions (i.e. abdominal obesity, impaired glucose tolerance, hypertriglyceridemia, decreased HDL cholesterol, and/or hypertension) that concour in the development of cardiovascular disease and diabetes. MetS individuals often show adverse cardiac remodeling and myocardial dysfunction even in the absence of overt coronary artery disease or valvular affliction. Diastolic impairment and hypertrophy are hallmarks of MetS-related cardiac remodeling and represent the leading cause of heart failure with preserved ejection fraction (HFpEF). Altered cardiomyocyte function, increased neurohormonal tone, interstitial fibrosis, coronary microvascular dysfunction, and a myriad of metabolic abnormalities have all been implicated in the development and progression of adverse cardiac remodeling related to MetS. However, despite the enormous amount of literature produced on this argument, HF remains a leading cause of morbidity and mortality in such population. The early detection of initial adverse cardiac remodeling would enable the optimal implementation of effective therapies aiming at preventing the progression of the disease to the symptomatic phase. Beyond conventional imaging techniques, such as echocardiography, cardiac tomography, and magnetic resonance, novel post-processing tools and techniques provide information on the biological processes that underlie metabolic heart disease. In this review, we summarize the pathophysiology of MetS-related cardiac remodeling and illustrate the relevance of state-of-the-art multimodality cardiac imaging to identify and quantify the degree of myocardial involvement, prognosticate long-term clinical outcome, and potentially guide therapeutic strategies.

Exploring potential mediators of the cardiovascular benefit of dulaglutide in type 2 diabetes patients in REWIND

BACKGROUND

The REWIND trial demonstrated cardiovascular (CV) benefits to patients with type 2 diabetes and multiple CV risk factors or established CV disease. This exploratory analysis evaluated the degree to which the effect of dulaglutide on CV risk factors could statistically account for its effects on major adverse cardiovascular events (MACE) in the REWIND trial.

METHODS

Potential mediators of established CV risk factors that were significantly reduced by dulaglutide were assessed in a post hoc analysis using repeated measures mixed models and included glycated hemoglobin (HbA1c), body weight, waist-to-hip ratio, systolic blood pressure, low-density lipoprotein (LDL), and urine albumin/creatinine ratio (UACR). These factors, for which the change in level during follow-up was significantly associated with incident MACE, were identified using Cox regression modeling. Each identified variable was then included as a covariate in the Cox model assessing the effect of dulaglutide on MACE to estimate the degree to which the hazard ratio of dulaglutide vs placebo was attenuated. The combined effect of the variables associated with attenuation was assessed by including all variables in an additional Cox model.

RESULTS

Although all evaluated variables were significantly improved by treatment, only changes in HbA1c and UACR were associated with MACE and a reduction in the effect of dulaglutide on this outcome was observed. The observed hazard ratio for MACE for dulaglutide vs placebo reduced by 36.1% by the updated mean HbA1c, and by 28.5% by the updated mean UACR. A similar pattern was observed for change from baseline in HbA1c and UACR and a reduction of 16.7% and 25.4%, respectively in the hazard ratio for MACE with dulaglutide vs placebo was observed. When HbA1c and UACR were both included, the observed hazard ratio reduced by 65.4% for the updated mean and 41.7% for the change from baseline with no HbA1c-UACR interaction (P interaction = 0.75 and 0.15, respectively).

CONCLUSIONS

Treatment-induced improvement in HbA1c and UACR, but not changes in weight, systolic blood pressure, or LDL cholesterol, appear to partly mediate the beneficial effects of dulaglutide on MACE outcomes. These observations suggest that the proven effects of dulaglutide on cardiovascular disease benefit are partially related to changes in glycemic control and albuminuria, with residual unexplained benefit. Clinicaltrials.gov; Trial registration number: NCT01394952. URL: https://clinicaltrials.gov/ct2/show/NCT01394952.

Molecular insights into ago-allosteric modulation of the human glucagon-like peptide-1 receptor

The glucagon-like peptide-1 (GLP-1) receptor is a validated drug target for metabolic disorders. Ago-allosteric modulators are capable of acting both as agonists on their own and as efficacy enhancers of orthosteric ligands. However, the molecular details of ago-allosterism remain elusive. Here, we report three cryo-electron microscopy structures of GLP-1R bound to (i) compound 2 (an ago-allosteric modulator); (ii) compound 2 and GLP-1; and (iii) compound 2 and LY3502970 (a small molecule agonist), all in complex with heterotrimeric G_s. The structures reveal that compound 2 is covalently bonded to C347 at the cytoplasmic end of TM6 and triggers its outward movement in cooperation with the ECD whose N terminus penetrates into the GLP-1 binding site. This allows compound 2 to execute positive allosteric modulation through enhancement of both agonist binding and G protein coupling. Our findings offer insights into the structural basis of ago-allosterism at GLP-1R and may aid the design of better therapeutics.

The glucagon-like peptide-1 (GLP-1) receptor is a key regulator of glucose homeostasis and a drug target for type 2 diabetes but available GLP-1R agonists are suboptimal due to several side-effects. Here authors report the cryo-EM structure of GLP-1R bound to an ago-allosteric modulator in complex with heterotrimeric G_s which offers insights into the molecular details of ago-allosterism.

Therapeutic potential of targeting intestinal bitter taste receptors in diabetes associated with dyslipidemia

Intestinal release of incretin hormones after food intake promotes glucose-dependent insulin secretion and regulates glucose homeostasis. The impaired incretin effects observed in the pathophysiologic abnormality of type 2 diabetes have triggered the pharmacological development of incretin-based therapy through the activation of glucagon-like peptide-1 (GLP-1) receptor, including GLP-1 receptor agonists (GLP-1 RAs) and dipeptidyl peptidase 4 (DPP4) inhibitors. In the light of the mechanisms involved in the stimulation of GLP-1 secretion, it is a fundamental question to explore whether glucose and lipid homeostasis can be manipulated by the digestive system in response to nutrient ingestion and taste perception along the gastrointestinal tract. While glucose is a potent stimulant of GLP-1 secretion, emerging evidence highlights the importance of bitter tastants in the enteroendocrine secretion of gut hormones through activation of bitter taste receptors. This review summarizes bitter chemosensation in the intestines for GLP-1 secretion and metabolic regulation based on recent advances in biological research of bitter taste receptors and preclinical and clinical investigation of bitter medicinal plants, including bitter melon, hops strobile, and berberine-containing herbs (e.g. coptis rhizome and barberry root). Multiple mechanisms of action of relevant bitter phytochemicals are discussed with the consideration of pharmacokinetic studies. Current evidence suggests that specific agonists targeting bitter taste receptors, such as human TAS2R1 and TAS2R38, may provide both metabolic benefits and anti-inflammatory effects with the modulation of the enteroendocrine hormone secretion and bile acid turnover in metabolic syndrome individuals or diabetic patients with dyslipidemia-related comorbidities.

High protein diet leads to prediabetes remission and positive changes in incretins and cardiovascular risk factors

BACKGROUND AND AIMS

High Protein diets may be associated with endocrine responses that favor improved metabolic outcomes. We studied the response to High Protein (HP) versus High Carbohydrate (HC) Diets in terms of incretin hormones GLP-1 and GIP, the hunger hormone ghrelin and BNP, which is associated with cardiac function. We hypothesized that HP diets induce more pronounced release of glucose lowering hormones, suppress hunger and improve cardiac function.

METHODS AND RESULTS

24 obese women and men with prediabetes were recruited and randomized to either a High Protein (HP) (n = 12) or High Carbohydrate (HC) (n = 12) diet for 6 months with all food provided. OGTT and MTT were performed and GLP-1, GIP, Ghrelin, BNP, insulin and glucose were measured at baseline and 6 months on the respective diets. Our studies showed that subjects on the HP diet had 100% remission of prediabetes compared to only 33% on the HC diet with similar weight loss. HP diet subjects had a greater increase in (1) OGTT GLP-1 AUC(p = 0.001) and MTT GLP-1 AUC(p = 0.001), (2) OGTT GIP AUC(p = 0.005) and MTT GIP AUC(p = 0.005), and a greater decrease in OGTT ghrelin AUC(p = 0.005) and MTT ghrelin AUC(p = 0.001) and BNP(p = 0.001) compared to the HC diet at 6 months.

CONCLUSIONS

This study demonstrates that the HP diet increases GLP-1 and GIP which may be responsible in part for improved insulin sensitivity and β cell function compared to the HC diet. HP ghrelin results demonstrate the HP diet can reduce hunger more effectively than the HC diet. BNP and other CVRF, metabolic parameters and oxidative stress are significantly improved compared to the HC diet. CLINICALTRIALS.

GOV IDENTIFIER

NCT01642849.

Dulaglutide Alleviates LPS-Induced Injury in Cardiomyocytes

BACKGROUND AND PURPOSE

Sepsis is a severe infection-induced disease with multiple organ failure, and sepsis-induced cardiomyopathy is a fatal condition. Inflammatory response and oxidative stress are reported to be involved in the development of sepsis-induced cardiomyopathy. Dulaglutide is a novel antidiabetic agent that is currently reported to exert an anti-inflammatory effect. The present study aims to explore the potential protective property of dulaglutide on lipopolysaccharide (LPS)-induced injury on cardiomyocytes.

METHODS

LPS was used to induce an in vitro injury model on cardiomyocytes. The mitochondrial reactive oxygen species (ROS) level was detected using MitoSOX red, and reduced glutathione (GSH) was measured to evaluate the status of oxidative stress in H9c2 myocardial cells. The expressions of NADPH oxidase-1 (NOX-1) and inducible nitric oxidesynthase (iNOS) were determined using real-time PCR and western blot analysis. Real-time PCR and enzyme-linked immunosorbent assay (ELISA) were both used to detect the expressions and concentrations of tumor necrosis factor-α, interleukin-1β, interleukin-17, matrix metalloproteinase-2, and matrix metalloproteinase-9 in H9c2 myocardial cells, respectively. The production of nitric oxide (NO) was measured using the Griess reagent. The levels of creatine kinase isoenzyme-MB (CK-MB) and cardiac troponin I (cTnI) were detected using ELISA. Western blot was utilized to determine the expressions of toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88), and p-NF-κB p65 in H9c2 myocardial cells in the nucleus.

RESULTS

First, dulaglutide ameliorated LPS-induced oxidative stress by suppressing the production of mitochondrial ROS and elevating the level of reduced GSH, as well as downregulating NOX-1. Second, the LPS-induced cardiomyocyte injury was alleviated by dulaglutide through downregulating CK-MB and cTnI, accompanied by inhibiting iNOS expression and NO production. Lastly, the production of inflammatory factors and upregulation of MMPs induced by LPS were both significantly reversed by dulaglutide through suppressing the TLR4/Myd88/NF-κB signaling pathway.

CONCLUSIONS

Dulaglutide alleviated LPS-induced injury in cardiomyocytes by inhibiting inflammation and oxidative stress.

Treating Arterial Ageing in Patients with Diabetes: From Mechanisms to Effective Drugs

Diabetes mellitus is a major healthcare problem. It is not only characterized by hyperglycemia and chronic complications, but in longer lasting diabetes and a longer living population, it is also associated with accelerated arterial ageing, which importantly contributes to cardiovascular complications. The accelerated arterial ageing in patients with diabetes should be considered separately from arterial ageing in patients without diabetes. Basic and clinical research have allowed better insight into the mechanisms of arterial ageing. In a simplified mechanistic way, it could be considered that the three tightly connected cornerstone characteristics of arterial ageing in patients with diabetes are: phenotypic presentation as endothelial dysfunction and arterial stiffness, and the underlying basic ageing-facilitating mechanism represented as the impaired expression of genetic longevity pathways. Currently, specific drugs for preventing/treating arterial ageing are not available. Therefore, we aimed to review the capacity of available drugs, particularly antidiabetic drugs, to interfere with the arterial ageing process. In the near future, these characteristics could help to guide therapy in patients with diabetes. Overall, it appears that arterial ageing could become a new target in diabetes. The expanding knowledge regarding the capability of antidiabetic drugs and other available drugs to inhibit/delay arterial aging is therefore essential.

Association between fasting insulin and C-reactive protein among adults without diabetes using a two-part model: NHANES 2005-2010

INTRODUCTION

Chronic inflammation is associated with the development, progression and long-term complications of type 2 diabetes. Hyperglycemia is associated with chronic low-grade inflammation, and thus has become the focus of many screening and treatment recommendations. We hypothesize that insulin may also be associated with inflammation and may be an additional factor to consider in screening and treatment.

METHODS

This study used National Health and Nutrition Examination Survey data from 2005 to 2010 to analyze the association between fasting insulin and C-reactive protein (CRP). A two-part model was used due to the high number of values reported as 0.1 mg/L. Two models were analyzed, both with and without the addition of waist circumference to other covariates in the model.

RESULTS

The final sample included 4527 adults with a mean age of 43.31 years. In the first model, higher fasting insulin was associated with increased odds of CRP > 0.1 mg/L (OR = 1.02, p < .001) and with higher CRP (β = 0.03, p < .001). In the adjusted model, including waist circumference as a covariate, higher fasting insulin was not associated with CRP > 0.1 mg/L (OR = 1.00, p = .307) but the association between higher fasting insulin and higher continuous CRP remained significant (β = 0.01, p = .012).

CONCLUSION

This study found that higher fasting insulin is associated with higher CRP. These results suggest that treatment approaches that simultaneously decrease insulin levels as well as glucose levels may provide additive anti-inflammatory effects, and therefore may improve long-term outcomes for adults with type 2 diabetes.

Effects of bariatric surgery on lipid-lipoprotein profile

Most patients with severe obesity will present some lipid-lipoprotein abnormalities. The atherogenic dyslipidemia associated with severe obesity is characterized by elevated fasting and postprandial triglyceride levels, low high-density lipoprotein cholesterol concentrations, and increased proportion of small and dense low-density lipoproteins. Bariatric surgery has been proven safe and successful in terms of long-term weight loss and improvement in obesity co-existing metabolic conditions including lipid-lipoprotein abnormalities. Nevertheless, bariatric surgery procedures are not all equivalent. We conducted a comprehensive critical analysis of the literature related to severe obesity, bariatric surgery and lipid-lipoprotein metabolism/profile. In this review, we described the metabolic impacts of different bariatric surgery procedures on the lipid-lipoprotein profile, and the mechanisms linking bariatric surgery and dyslipidemia remission based on recent epidemiological, clinical and preclinical studies. Further mechanistic studies are essential to assess the potential of bariatric/metabolic surgery in the management of lipid-lipoprotein abnormalities associated with severe obesity. Understanding the beneficial effects of various bariatric surgery procedures on the lipid-lipoprotein metabolism and profile may result in a wider acceptance of this strategy as a long-term metabolic treatment of lipid-lipoprotein abnormalities in severe obesity and help clinician to develop an individualized and optimal approach in the management of dyslipidemia associated with severe obesity. BRIEF SUMMARY: Abnormal lipid-lipoprotein profile is frequent in patients with severe obesity. Significant improvements in lipid-lipoprotein profile following bariatric surgery occur early in the postoperative period, prior to weight loss, and persists throughout the follow-up. The mechanisms that facilitate the remission of dyslipidemia after bariatric surgery, may involve positive effects on adipose tissue distribution/function, insulin sensitivity, liver fat content/function and lipid-lipoprotein metabolism.

Characterizing Effects of Antidiabetic Drugs on Heart Rate, Systolic and Diastolic Blood Pressure

A model-based meta-analysis was performed with reported data from obese subjects and patients with type 2 diabetes (T2DM) to characterize the effects of dipeptidyl peptidase 4 (DPP4) inhibitors, gastric inhibitory polypeptides (GIPs), glucagon-like peptide-1 (GLP1), and dual GIP/GLP1 agonists, or a combination of these antidiabetic drugs (ADs) on heart rate (HR), diastolic blood pressure (DBP), and systolic blood pressure (SBP). A systematic literature search and review after the Cochrane method identified sources for investigational and approved ADs resulted in a comprehensive database with data from 178 clinical studies in obese subjects and patients with T2DM. Results indicated that there were AD class-dependent effects on HR and SBP, whereas no clear AD-related effects on DBP were found. All AD classes, except for DPP4 inhibitors, increased HR. The largest increase of 12 bpm was seen with GLP1 receptor agonists. All AD classes appeared to decrease SBP. DPP4 inhibitors were associated with a marginal decrease of ~ 1 mmHg, whereas GLP1 and GIP/GLP1 dual agonists exhibited the largest decrease of ~ 3 mmHg in SBP. AD-related effects were similar in obese subjects and patients with T2DM. In conclusion, there are clinically relevant AD-related effects on both HR and SBP, but not on DBP. DPP4 inhibitors are associated with the smallest (if at all) effects on HR and SBP, whereas GLP1 inhibitors exhibited the largest effects on these two cardiovascular end points. Additional studies are warranted to further investigate how AD-related SBP decreases combined with HR increases affect long-term cardiovascular mortality.

Role of berries in vascular function: a systematic review of human intervention studies

CONTEXT

Berries are a source of polyphenols with recognized health-promoting activities. Several studies suggest that consumption of berries may improve vascular function.

OBJECTIVE

The aim of this systematic review is to provide evidence of short- and long-term benefits of berries on outcomes of vascular function.

DATA SOURCES

Human intervention studies were collected from PubMed and Scopus databases.

STUDY SELECTION

Studies were eligible if they investigated the effects of acute or chronic berry consumption on one or more markers of vascular function in humans and provided a characterization of the berry polyphenolic content. Only randomized controlled trials were included, and studies were excluded if berries were combined with other foods.

DATA EXTRACTION

After selection, 22 randomized controlled trials were included and analyzed, most of which were performed in healthy individuals or patients with cardiovascular risk factors.

RESULTS

The overall results seem to suggest a protective role of berries in vascular function, likely dependent on the time of exposure, the type and dose of berry, and the biomarkers analyzed. Flow-mediated dilation and reactive hyperemia index (markers of vascular reactivity) improved following short-term interventions, while pulse wave velocity and augmentation index (markers of arterial stiffness) improved only after medium- to long-term intervention.

CONCLUSIONS

Current evidence suggests that berries, at physiological relevant doses, may have a role in the modulation of vascular function and stiffness. High-quality human intervention trials are encouraged in order to strengthen these findings and to better elucidate the mechanisms involved in such modulation.

Current Data Regarding the Relationship between Type 2 Diabetes Mellitus and Cardiovascular Risk Factors

Reducing cardiovascular risk (CVR) is the main focus of diabetes mellitus (DM) management nowadays. Complex pathogenic mechanisms that are the subject of this review lead to early and severe atherosclerosis in DM patients. Although it is not a cardiovascular disease equivalent at the moment of diagnosis, DM subjects are affected by numerous cardiovascular complications, such as acute coronary syndrome, stroke, or peripheral artery disease, as the disease duration increases. Therefore, early therapeutic intervention is mandatory and recent guidelines focus on intensive CVR factor management: hyperglycaemia, hypertension, and dyslipidaemia. Most important, the appearance of oral or injectable antidiabetic medication such as SGLT-2 inhibitors or GLP-1 agonists has proven that an antidiabetic drug not only reduces glycaemia, but also reduces CVR by complex mechanisms. A profound understanding of intimate mechanisms that generate atherosclerosis in DM and ways to inhibit or delay them are of the utmost importance in a society where cardiovascular morbidity and mortality are predominant.

Metabolic and cardiovascular benefits of GLP-1 agonists, besides the hypoglycemic effect (Review)

Patients with type 2 diabetes exhibit higher cardiovascular risk than normal individuals. Optimal blood glucose levels are rarely achieved in diabetic patients. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) have emerged as a new antidiabetic drug class with multiple metabolic effects. Some trials have evaluated their safety, but it has been recently demonstrated that this new class has cardiovascular benefits, through other mechanisms than glycemic control. The use of GLP-1RAs was associated with a significant reduction of cardiovascular and all-cause mortality, with a safe profile related to pancreatitis or thyroid cancer, as compared with placebo. This review presents the cardiovascular and metabolic benefits of GLP-1 RAs versus placebo, in patients with type 2 diabetes. Semaglutide and liraglutide demonstrated a reduction in cardiovascular events, with similar rates on cardiovascular mortality. Ongoing trials assess the cardiovascular benefits and side effects of dulaglutide treatment. Exenatide and liraglutide demonstrated the decrease of blood pressure values, weight reduction and improvement of dyslipidemia. Liraglutide induced, both in vivo and in vitro, an improvement of blood circulation, increasing the nitric oxide level and inhibiting the adhesion and procoagulant factors. Also, liraglutide demonstrated beneficial effects on cardiac remodeling after myocardial infarction, but more large trials are required. However, the international guidelines recommend using GLP-1 RAs as first-line therapy in type 2 diabetes patients with high cardiovascular risk or as first-line agents in patients intolerant to metformin.

An Overview of Prospective Drugs for Type 1 and Type 2 Diabetes

Aims:

The aim of this study is to provide an overview of several emerging anti-diabetic molecules.

Background:

Diabetes is a complex metabolic disorder involving the dysregulation of glucose homeostasis at various levels. Insulin, which is produced by β-pancreatic cells, is a chief regulator of glucose metabolism, regulating its consumption within cells, which leads to energy generation or storage as glycogen. Abnormally low insulin secretion from β-cells, insulin insensitivity, and insulin tolerance lead to higher plasma glucose levels, resulting in metabolic complications. The last century has witnessed extraordinary efforts by the scientific community to develop anti-diabetic drugs, and these efforts have resulted in the discovery of exogenous insulin and various classes of oral anti-diabetic drugs.

Objective:

Despite these exhaustive anti-diabetic pharmaceutical and therapeutic efforts, long-term glycemic control, hypoglycemic crisis, safety issues, large-scale economic burden and side effects remain the core problems.

Method:

The last decade has witnessed the development of various new classes of anti-diabetic drugs with different pharmacokinetic and pharmacodynamic profiles. Details of their FDA approvals and advantages/disadvantages are summarized in this review.

Results:

The salient features of insulin degludec, sodium-glucose co-transporter 2 inhibitors, glucokinase activators, fibroblast growth factor 21 receptor agonists, and GLP-1 agonists are discussed.

Conclusion :

In the future, these new anti-diabetic drugs may have broad clinical applicability. Additional multicenter clinical studies on these new drugs should be conducted.

Antihyperglycemic therapies and cardiovascular outcomes in patients with type 2 diabetes mellitus: State of the art and future directions

Type 2 diabetes mellitus is a progressive chronic disease and is an established risk factor for cardiovascular disease. Until recently, the cardiovascular safety and efficacy of antihyperglycemic drugs remained uncertain. However, after the changes in regulatory guidance in 2008, a wealth of data has been generated, expanding the focus of the treatment of diabetes from blood glucose control to the prevention of macro-and microvascular complications and improvement in mortality. This article will review cardiovascular outcome trials of antihyperglycemic agents and provide overview of ongoing trials.

Dulaglutide-combined basal plus correction insulin therapy contributes to ideal glycemic control in non-critical hospitalized patients

AIMS/INTRODUCTION

We investigated whether dulaglutide (DU)-combined conventional insulin therapy is beneficial for glycemic control in non-critically ill hospitalized patients with type 2 diabetes.

MATERIALS AND METHODS

This study was a prospective, randomized controlled pilot study. Participants were randomized to either basal-plus (BP) therapy, where basal insulin and corrective doses of regular insulin were administered before meals, or BP + DU therapy, where BP therapy was combined with DU. Blood glucose (BG) levels before and after every meal were measured for 7 days after assignment to groups. Because we consider the ideal BG during hospitalization to be within 100-180 mg/dL, we defined this range as the hospitalized ideal glucose range (hIGR). We compared the percentage of BG measurements within the hIGR among all BG measurements (%hIGR), mean BG, glucose variability and insulin dose between the two groups.

RESULTS

Of 54 patients, 27 were assigned to the BP group and 27 to the BP + DU group. The %hIGR was significantly higher (44% vs 56%, P < 0.001), and the frequency of BG >240 mg/dL and BG <70 mg/dL was significantly lower in the BP + DU group than in the BP group (both P < 0.001). The mean BG (183 ± 29 vs 162 ± 30 mg/dL, P < 0.05), standard deviation (P < 0.01), coefficient of variation (P < 0.01) and total regular insulin dose (P < 0.05) in the BP + DU group were significantly lower than those in the BP group. No significant side-effects were observed in either group.

CONCLUSIONS

BP + DU therapy reduced the frequency of hyperglycemia and hypoglycemia, and resulted in a lower glucose variability.

European Society of Cardiology/Heart Failure Association position paper on the role and safety of new glucose-lowering drugs in patients with heart failure

Type 2 diabetes mellitus (T2DM) is common in patients with heart failure (HF) and associated with considerable morbidity and mortality. Significant advances have recently occurred in the treatment of T2DM, with evidence of several new glucose-lowering medications showing either neutral or beneficial cardiovascular effects. However, some of these agents have safety characteristics with strong practical implications in HF [i.e. dipeptidyl peptidase-4 (DPP-4) inhibitors, glucagon-like peptide-1 receptor agonists (GLP-1 RA), and sodium-glucose co-transporter type 2 (SGLT-2) inhibitors]. Regarding safety of DPP-4 inhibitors, saxagliptin is not recommended in HF because of a greater risk of HF hospitalisation. There is no compelling evidence of excess HF risk with the other DPP-4 inhibitors. GLP-1 RAs have an overall neutral effect on HF outcomes. However, a signal of harm suggested in two small trials of liraglutide in patients with reduced ejection fraction indicates that their role remains to be defined in established HF. SGLT-2 inhibitors (empagliflozin, canagliflozin and dapagliflozin) have shown a consistent reduction in the risk of HF hospitalisation regardless of baseline cardiovascular risk or history of HF. Accordingly, SGLT-2 inhibitors could be recommended to prevent HF hospitalisation in patients with T2DM and established cardiovascular disease or with multiple risk factors. The recently completed trial with dapagliflozin has shown a significant reduction in cardiovascular mortality and HF events in patients with HF and reduced ejection fraction, with or without T2DM. Several ongoing trials will assess whether the results observed with dapagliflozin could be extended to other SGLT-2 inhibitors in the treatment of HF, with either preserved or reduced ejection fraction, regardless of the presence of T2DM. This position paper aims to summarise relevant clinical trial evidence concerning the role and safety of new glucose-lowering therapies in patients with HF.

Consensus Recommendations on GLP-1 RA Use in the Management of Type 2 Diabetes Mellitus: South Asian Task Force

The advent of incretin mimetics such as glucagon-like peptide-1 receptor agonists (GLP-1 RAs) has enriched the armamentarium for diabetes management owing to their glycaemic as well as extra-glycaemic benefits. The approval status and availability of this class of drugs vary widely across the globe. Being a relatively newer class of drug with numerous benefits, several national and international guidelines are working towards addressing clinical questions pertaining to the optimal use of GLP-1 RAs for the management of diabetes. Although the newer class of drugs are associated with significant benefits such as patient-centric approach, these drugs demand the providers to be vigilant and knowledgeable about the medication. The South Asian population is at higher risk of type 2 diabetes mellitus (T2DM) because of their genetic predisposition and lifestyle changes. Hence, prevention and management of T2DM and its associated complications in this population are of paramount importance. The current report aims to present an overview of current knowledge on GLP-1 RAs based on pragmatic review of the available clinical evidence. In addition, this report is a consensus of expert endocrinologists representing South Asian countries including India, Pakistan, Bangladesh, Nepal, Sri Lanka, Afghanistan and the Maldives on essential recommendations related to the use of GLP-1 RAs in a real-world scenario.

The development of an oral GLP-1 receptor agonist for the management of type 2 diabetes: evidence to date

Glucagon-like peptide 1 receptor agonists (GLP1-RA) are prominent agents in the therapeutics of type 2 diabetes mellitus due to their exemplary efficacy in both preprandial and postprandial glycemia, their safety, low risk of hypoglycemia, their multilevel pathophysiological superiority, weight loss and importantly the observed benefits in cardiovascular disease reduction. Their major drawback is the subcutaneous route of administration, constituting a barrier to adoption and reason for treatment discontinuation. Thus, the development of an oral GLP1-RA agent would promote medication adherence and quality of life, further consolidating its beneficial effects in real-life clinical practice. However, this task is hampered by suboptimal gastrointestinal protein absorption. Yet, the introduction of oral semaglutide, a modified form of semaglutide with the addition of a carrier sodium N-(8-[2-hydroxybenzoyl] amino) caprylate, may have provided a safe and effective way to reach systemic circulation while other molecules are in development. Whether this molecule still has the impressive cardiovascular effects demonstrated with the use of its precursor remains to be explored. However, to date, its efficacy and safety have already been showcased in a randomized trial. More research is warranted in order to further consolidate these findings across different type 2 diabetes mellitus (T2DM) subpopulations, and adequately powered studies with a longer follow-up that would allow the exploration of microvascular and macrovascular complications are needed. Finally, studies comparing oral semaglutide and similar molecules with other currently established antidiabetic agents to evaluate the relative efficacy, the cost-effectiveness and further understand its place in T2DM therapeutic algorithm are needed. This review focuses on the development of oral GLP1-RA agents and summarizes the challenges, milestones and expected benefits associated with a successful introduction.

Glucagon-Like Peptide-1 Receptor Agonist Attenuates Autophagy to Ameliorate Pulmonary Arterial Hypertension through Drp1/NOX- and Atg-5/Atg-7/Beclin-1/LC3β Pathways

Mitochondrial dysfunction is associated with cardiovascular diseases and diabetes. Pulmonary arterial hypertension (PAH) is characterized by pulmonary vascular remodeling, and the abnormal proliferation, apoptosis and migration of pulmonary arterial smooth muscle cells (PASMCs). The glucagon-like peptide-1 (GLP-1) receptor agonist, liraglutide, has been shown to prevent pulmonary hypertension in monocrotaline-exposed rats. The aim of this study was to investigate the effect of liraglutide on autophagy, mitochondrial stress and apoptosis induced by platelet-derived growth factor BB (PDGF-BB). PASMCs were exposed to PDGF-BB, and changes in mitochondrial morphology, fusion-associated protein markers, and reactive oxygen species (ROS) production were examined. Autophagy was assessed according to the expressions of microtubule-associated protein light chain 3 (LC3)-II, LC3 puncta and Beclin-1. Western blot analysis was used to assess apoptosis, mitochondrial stress and autophagy markers. Liraglutide significantly inhibited PDGF-BB proliferation, migration and motility in PASMCs. PDGF-BB-induced ROS production was mitigated by liraglutide. Liraglutide increased the expression of α-smooth muscle actin (α-SMA) and decreased the expression of p-Yes-associated protein (p-YAP), inhibited autophagy-related protein (Atg)-5, Atg-7, Beclin-1 and the formation of LC3-β and mitochondrial fusion protein dynamin-related (Drp)1. Therefore, liraglutide can mitigate the proliferation of PASMCs via inhibiting cellular Drp1/nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOX) pathways and Atg-5/Atg-7/Beclin-1/LC3β-dependent pathways of autophagy in PAH.

Nonglycemic Effects of GLP-1 Agonists: From a Starling to Lizards to People

With the approval of exenatide in 2005, physicians had a new class of hypoglycemic agents available for the treatment of type 2 diabetes-the glucagon-like peptide-1 receptor agonists (or GLP-1 receptor agonists). As of this writing, there are seven drugs in this class available in the United States. In addition to demonstrating either cardiovascular risk neutrality or overt benefit, as now mandated by the United States Food and Drug Administration (FDA), many of these drugs have other, unexpected actions. It is our goal to outline these actions, some beneficial, some not. We have reviewed English-language articles in this area, not for an exhaustive study, but rather a broad search to define current understanding and perhaps generate further investigation.

Novel Site-Specific Fatty Chain-Modified GLP-1 Receptor Agonist with Potent Antidiabetic Effects

Glucagon-like peptide-1 receptor (GLP-1R) agonists have emerged as treatment options for type 2 diabetes mellitus (T2DM). Here, we designed a high-throughput GLP-1R extracellular domain (ECD)-based system that enabled the screening of high-potency receptor-biased GLP-1R agonists demonstrating new pharmacological virtues. Firstly, six 12-mer peptides (termed PEP01–06), screened from a large phage displayed peptide library were fused to the N-terminus of Exendin-4 (29–39) to generate PEP07–12. By the use of four lysine-altered PEP07 (PEP13–16) as the starting point, a series of fatty chain conjugates (PEP17–20) were synthesized and evaluated by in vitro GLP-1R-based cell assays. In addition, the acute and long-term in vivo effects on diet-induced obesity (DIO) mice were further evaluated. All four conjugates showed good receptor activation efficacy, and PEP20 was selected to undergo further assessment. Preclinical experiments in DIO mice demonstrated that PEP20 had significant insulinotropic activities and glucose-lowering abilities. Moreover, a prolonged antidiabetic effect of PEP20 was also observed by the hypoglycemic test in DIO mice. Furthermore, long-term treatment with PEP20 achieved beneficial effects on the food intake, weight gain, hemoglobin A1C (HbA1C) lowering activity, and glucose tolerance compared with the control and was similar to the Liraglutide. In conclusion, PEP20, a GLP-1R ECD-biased agonist, may provide a novel therapeutic approach to T2DM.

Glucagon-like peptide-1 attenuates endoplasmic reticulum stress-induced apoptosis in H9c2 cardiomyocytes during hypoxia/reoxygenation through the GLP-1R/PI3K/Akt pathways

Endoplasmic reticulum (ER) stress-induced apoptosis is a major cause of myocardial ischemia/reperfusion (I/R) injury. Emerging evidence indicates that glucagon-like peptide-1 (GLP-1) has potential cardioprotective effects. However, the precise mechanisms underlying the involvement of GLP-1 in I/R injury remain largely unknown. In the present study, we aimed to determine whether GLP-1 attenuates hypoxia/reoxygenation (H/R) injury in cardiomyocytes and to further elucidate the underlying signaling pathway. The results indicate that GLP-1 reversed the increased apoptotic ratio, the increased lactate dehydrogenase (LDH) levels, the reduced cell viability, the increased Caspase-3 activity, and the increased Bax/Bcl-2 ratio caused by H/R. Importantly, GLP-1 significantly decreased the expression of H/R-induced ER stress proteins (GRP78, CHOP) and Caspase-12. In addition, we found that GLP-1 increased the expression of p-Akt in H9c2 cells with H/R injuries, and that the protective action of GLP-1 against H/R-induced injury was blocked by the GLP-1 receptor (GLP-1R) inhibitor Exendin9-39 and the PI3K inhibitor LY294002. Exendin9-39 and LY294002 also blocked the downregulation of ER stress protein expression by GLP-1, after H/R injury. Therefore, we have shown that GLP-1 exerts its cardioprotective effects by alleviating ER stress-induced apoptosis due to H/R injury and that these effects are most likely associated with the activation of GLP-1R/PI3K/Akt signaling pathway.

Cardiovascular protection in type 2 diabetes: Insights from recent outcome trials

This review examines recent randomized controlled cardiovascular (CV) outcome trials of glucose-lowering therapies in type 2 diabetes and their impact on the treatment of patients with type 2 diabetes. The trials were designed to comply with regulatory requirements to confirm that major adverse cardiac events (MACE) are not detrimentally affected by such therapies. Trials involving dipeptidyl peptidase-4 (DPP-4) inhibitors did not alter a composite MACE outcome comprising CV deaths, non-fatal myocardial infarction and non-fatal stroke; however, the possibility that some members of this class might incur a small increased risk or worsening of heart failure cannot be excluded. Some studies on glucagon-like peptide-1 receptor agonists (liraglutide: LEADER trial; semaglutide: SUSTAIN-6 trial) found significant benefits for MACE, while treatment with sodium-glucose co-transporter-2 inhibitors (empagliflozin: EMPA-REG OUTCOME trial; canagliflozin: CANVAS trial) also significantly reduced MACE and reduced hospitalization for heart failure. Comparisons among trials are complicated by variance in the populations recruited, particularly CV status at randomization, and differences in trial design, data collection and analyses. A large proportion of patients recruited into these trials have previously experienced adverse CV events; thus, the therapies are mostly assessing secondary prevention of a further event. This contrasts with the overall type 2 diabetes population receiving glucose-lowering therapies, of whom the majority will not have had MACE and will be regarded as primary prevention. Overall, the trials provide reassuring evidence that new glucose-lowering medications do not adversely affect CV events and some of these agents may offer CV protection.

GLP-1RAs in type 2 diabetes: mechanisms that underlie cardiovascular effects and overview of cardiovascular outcome data

Patients with type 2 diabetes (T2DM) have a substantial risk of developing cardiovascular disease. The strong connection between the severity of hyperglycaemia, metabolic changes secondary to T2DM and vascular damage increases the risk of macrovascular complications. There is a challenging demand for the development of drugs that control hyperglycaemia and influence other metabolic risk factors to improve cardiovascular outcomes such as cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, hospitalization for unstable angina and heart failure (major adverse cardiovascular events). In recent years, introduction of the new drug class of glucagon-like peptide-1 receptor agonists (GLP-1RAs) has changed the treatment landscape as GLP-1RAs have become well-established therapies in T2DM. The benefits of GLP-1RAs are derived from their pleiotropic effects, which include appetite control, glucose-dependent secretion of insulin and inhibition of glucagon secretion. Importantly, their beneficial effects extend to the cardiovascular system. Large clinical trials have evaluated the cardiovascular effects of GLP-1RAs in patients with T2DM and elevated risk of cardiovascular disease and the results are very promising. However, important aspects still require elucidation, such as the specific mechanisms involved in the cardioprotective effects of these drugs. Careful interpretation is necessary because of the heterogeneity across the trials concerning the definition of cardiovascular risk or cardiovascular disease, baseline characteristics, routine care and event rates. The aim of this review is to describe the main clinical aspects of the GLP-1RAs, compare them using data from both the mechanistic and randomized controlled trials and discuss potential reasons for improved cardiovascular outcomes observed in these trials. This review may help clinicians to decide which treatment is most appropriate in reducing cardiovascular risk in patients with T2DM.

Prevalence and pathophysiology of early dumping in patients after primary Roux-en-Y gastric bypass during a mixed-meal tolerance test

BACKGROUND

Early dumping is a poorly defined and incompletely understood complication after Roux-en-Y gastric (RYGB).

OBJECTIVE

We performed a mixed-meal tolerance test in patients after RYGB to address the prevalence of early dumping and to gain further insight into its pathophysiology.

SETTING

The study was conducted in a regional hospital in the northern part of the Netherlands.

METHODS

From a random sample of patients who underwent primary RYGB between 2008 and 2011, 46 patients completed the mixed-meal tolerance test. The dumping severity score for early dumping was assessed every 30 minutes. A sum score at 30 or 60 minutes of ≥5 and an incremental score of ≥3 points were defined as indicating a high suspicion of early dumping. Blood samples were collected at baseline, every 10 minutes during the first half hour, and at 60 minutes after the start.

RESULTS

The prevalence of a high suspicion of early dumping was 26%. No differences were seen for absolute hematocrit value, inactive glucagon-like peptide-1, and vasoactive intestinal peptide between patients with or without early dumping. Patients at high suspicion of early dumping had higher levels of active glucagon-like peptide-1 and peptide YY.

CONCLUSION

The prevalence of complaints at high suspicion of early dumping in a random population of patients after RYGB is 26% in response to a mixed-meal tolerance test. Postprandial increases in both glucagon-like peptide-1 and peptide YY are associated with symptoms of early dumping, suggesting gut L-cell overactivity in this syndrome.

Effect of linagliptin on oxidative stress markers in patients with type 2 diabetes: a pilot study

Background

Dipeptidyl peptidase-4 (DPP-4) inhibitors are commonly used for the treatment of type 2 diabetes and have been previously shown to prevent diabetic renal injury via various mechanisms, including the attenuation of oxidative stress. Therefore, we hypothesized that linagliptin, a DPP-4 inhibitor, attenuates oxidized stress and diabetic renal injury.

Methods

In total, 30 patients with type 2 diabetes who were undergoing treatment with linagliptin (5 mg) during the 3-month study period were enrolled. Oxidative stress markers [serum malondialdehyde-modified LDL (MDA-LDL) and urinary 8-hydroxydeoxyguanosine (8-OHdG)], an inflammatory marker (high-sensitive CRP), urinary albumin excretion, estimated GFR, and a urinary tubulointerstitial injury marker [urinary liver-type fatty acid-binding protein (L-FABP)] were evaluated at baseline and after 3 months of treatment.

Results

Following linagliptin treatment, serum MDA-LDL, serum HbA1c, and urinary L-FABP levels significantly decreased, while urinary 8-OHdG tended to decrease. In contrast, 1,5-AG levels increased, and high-sensitive CRP and urinary albumin excretion remained unchanged.

Conclusion

In this study, we demonstrated that linagliptin partially attenuated oxidative stress. We also demonstrated that linagliptin treatment reduced urinary L-FABP excretion, suggesting that renal tubule-interstitial injury may be attenuated by linagliptin (UMIN 000015308).

Molecular Mechanisms Underlying the Cardiovascular Benefits of SGLT2i and GLP-1RA

PURPOSE OF REVIEW

In addition to their effects on glycemic control, two specific classes of relatively new anti-diabetic drugs, namely the sodium glucose co-transporter-2 inhibitors (SGLT2i) and glucagon-like peptide-1 receptor agonists (GLP-1RA) have demonstrated reduced rates of major adverse cardiovascular events (MACE) in subjects with type 2 diabetes (T2D) at high risk for cardiovascular disease (CVD). This review summarizes recent experimental results that inform putative molecular mechanisms underlying these benefits.

RECENT FINDINGS

SGLT2i and GLP-1RA exert cardiovascular effects by targeting in both common and distinctive ways (A) several mediators of macro- and microvascular pathophysiology: namely (A1) inflammation and atherogenesis, (A2) oxidative stress-induced endothelial dysfunction, (A3) vascular smooth muscle cell reactive oxygen species (ROS) production and proliferation, and (A4) thrombosis. These agents also exhibit (B) hemodynamic effects through modulation of (B1) natriuresis/diuresis and (B2) the renin-angiotensin-aldosterone system. This review highlights that while GLP-1RA exert direct effects on vascular (endothelial and smooth muscle) cells, the effects of SGLT2i appear to include the activation of signaling pathways that prevent adverse vascular remodeling. Both SGLT2i and GLP-1RA confer hemodynamic effects that counter adverse cardiac remodeling.

Cardiometabolic Effects of Anti-obesity Pharmacotherapy

PURPOSE OF REVIEW

We review recent studies discussing the impact of pharmacologic agents for weight loss on clinical cardiovascular events, as well as cardiometabolic risk factors.

RECENT FINDINGS

Pharmacotherapy with current FDA-approved medications for weight loss can significantly improve known risk factors for the development of cardiovascular disease such as hypertension, hyperlipidemia, insulin resistance, inflammatory biomarkers, and the quantity of visceral fat, as well as non-alcoholic fatty liver disease. However, data regarding the actual reduction in clinical cardiovascular events with the use of weight loss medications is scarce. Pharmacotherapy for weight loss may have additional benefit in optimizing patient's cardiometabolic comorbidities and improving their clinical cardiovascular outcomes, but each drug should be carefully selected based upon individual patient characteristics.