Exenatide acutely increases heart rate in parallel with augmented sympathetic nervous system activation in healthy overweight males

Cyclic Adenosine Monophosphate in Cardiac and Sympathoadrenal GLP-1 Receptor Signaling: Focus on Anti-Inflammatory Effects

Glucagon-like peptide-1 (GLP-1) is a multifunctional incretin hormone with various physiological effects beyond its well-characterized effect of stimulating glucose-dependent insulin secretion in the pancreas. An emerging role for GLP-1 and its receptor, GLP-1R, in brain neuroprotection and in the suppression of inflammation, has been documented in recent years. GLP-1R is a G protein-coupled receptor (GPCR) that couples to Gs proteins that stimulate the production of the second messenger cyclic 3',5'-adenosine monophosphate (cAMP). cAMP, acting through its two main effectors, protein kinase A (PKA) and exchange protein directly activated by cAMP (Epac), exerts several anti-inflammatory (and some pro-inflammatory) effects in cells, depending on the cell type. The present review discusses the cAMP-dependent molecular signaling pathways elicited by the GLP-1R in cardiomyocytes, cardiac fibroblasts, central neurons, and even in adrenal chromaffin cells, with a particular focus on those that lead to anti-inflammatory effects by the GLP-1R. Fully elucidating the role cAMP plays in GLP-1R's anti-inflammatory properties can lead to new and more precise targets for drug development and/or provide the foundation for novel therapeutic combinations of the GLP-1R agonist medications currently on the market with other classes of drugs for additive anti-inflammatory effect.

Anti-Diabetic Therapy and Heart Failure: Recent Advances in Clinical Evidence and Molecular Mechanism

Diabetic patients have a two- to four-fold increase in the risk of heart failure (HF), and the co-existence of diabetes and HF is associated with poor prognosis. In randomized clinical trials (RCTs), compelling evidence has demonstrated the beneficial effects of sodium-glucose co-transporter-2 inhibitors on HF. The mechanism includes increased glucosuria, restored tubular glomerular feedback with attenuated renin-angiotensin II-aldosterone activation, improved energy utilization, decreased sympathetic tone, improved mitochondria calcium homeostasis, enhanced autophagy, and reduced cardiac inflammation, oxidative stress, and fibrosis. The RCTs demonstrated a neutral effect of the glucagon-like peptide receptor agonist on HF despite its weight-reducing effect, probably due to it possibly increasing the heart rate via increasing cyclic adenosine monophosphate (cAMP). Observational studies supported the markedly beneficial effects of bariatric and metabolic surgery on HF despite no current supporting evidence from RCTs. Bromocriptine can be used to treat peripartum cardiomyopathy by reducing the harmful cleaved prolactin fragments during late pregnancy. Preclinical studies suggest the possible beneficial effect of imeglimin on HF through improving mitochondrial function, but further clinical evidence is needed. Although abundant preclinical and observational studies support the beneficial effects of metformin on HF, there is limited evidence from RCTs. Thiazolidinediones increase the risk of hospitalized HF through increasing renal tubular sodium reabsorption mediated via both the genomic and non-genomic action of PPARγ. RCTs suggest that dipeptidyl peptidase-4 inhibitors, including saxagliptin and possibly alogliptin, may increase the risk of hospitalized HF, probably owing to increased circulating vasoactive peptides, which impair endothelial function, activate sympathetic tones, and cause cardiac remodeling. Observational studies and RCTs have demonstrated the neutral effects of insulin, sulfonylureas, an alpha-glucosidase inhibitor, and lifestyle interventions on HF in diabetic patients.

Links between Metabolic Syndrome and Hypertension: The Relationship with the Current Antidiabetic Drugs

Hypertension poses a significant burden in the general population, being responsible for increasing cardiovascular morbidity and mortality, leading to adverse outcomes. Moreover, the association of hypertension with dyslipidaemia, obesity, and insulin resistance, also known as metabolic syndrome, further increases the overall cardiovascular risk of an individual. The complex pathophysiological overlap between the components of the metabolic syndrome may in part explain how novel antidiabetic drugs express pleiotropic effects. Taking into consideration that a significant proportion of patients do not achieve target blood pressure values or glucose levels, more efforts need to be undertaken to increase awareness among patients and physicians. Novel drugs, such as incretin-based therapies and renal glucose reuptake inhibitors, show promising results in decreasing cardiovascular events in patients with metabolic syndrome. The effects of sodium-glucose co-transporter-2 inhibitors are expressed at different levels, including renoprotection through glucosuria, natriuresis and decreased intraglomerular pressure, metabolic effects such as enhanced insulin sensitivity, cardiac protection through decreased myocardial oxidative stress and, to a lesser extent, decreased blood pressure values. These pleiotropic effects are also observed after treatment with glucagon-like peptide-1 receptor agonists, positively influencing the cardiovascular outcomes of patients with metabolic syndrome. The initial combination of the two classes may be the best choice in patients with type 2 diabetes mellitus and multiple cardiovascular risk factors because of their complementary mechanisms of action. In addition, the novel mineralocorticoid receptor antagonists show significant cardio-renal benefits, as well as anti-inflammatory and anti-fibrotic effects. Overall, the key to better control of hypertension in patients with metabolic syndrome is to consider targeting multiple pathogenic mechanisms, using a combination of the different therapeutic agents, as well as drastic lifestyle changes. This article will briefly summarize the association of hypertension with metabolic syndrome, as well as take into account the influence of antidiabetic drugs on blood pressure control.

Effect of the Glucagon-Like Peptide-1 Receptor Agonists on Autonomic Function in Subjects with Diabetes: A Systematic Review and Meta-Analysis

BACKGROUND

In addition to the metabolic effects in diabetes, glucagon-like peptide 1 receptor (GLP-1R) agonists lead to a small but substantial increase in heart rate (HR). However, the GLP-1R actions on the autonomic nervous system (ANS) in diabetes remain debated. Therefore, this meta-analysis evaluates the effect of GLP-1R agonist on measures of ANS function in diabetes.

METHODS

According to the Cochrane Collaboration and Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement, we conducted a meta-analysis considering clinical trials in which the autonomic function was evaluated in diabetic subjects chronically treated with GLP-1R agonists. The outcomes were the change of ANS function measured by heart rate variability (HRV) and cardiac autonomic reflex tests (CARTs).

RESULTS

In the studies enrolled, HR significantly increased after treatment (P<0.001), whereas low frequency/high frequency ratio did not differ (P=0.410); no changes in other measures of HRV were detected. Considering CARTs, only the 30:15 value derived from lying-to-standing test was significantly lower after treatment (P=0.002), but only two studies reported this measurement. No differences in other CARTs outcome were observed.

CONCLUSION

The meta-analysis confirms the HR increase but seems to exclude an alteration of the sympatho-vagal balance due to chronic treatment with GLP-1R agonists in diabetes, considering the available measures of ANS function.

Mechanisms underlying the blood pressure lowering effects of dapagliflozin, exenatide, and their combination in people with type 2 diabetes: a secondary analysis of a randomized trial

Background

Sodium-glucose cotransporter-2 inhibitors (SGLT2i) and glucagon-like peptide-1 receptor agonists (GLP-1RA) lower blood pressure (BP). When SGLT2i and GLP-1RA are combined, synergistic effects on BP have been observed. The mechanisms underlying these BP reductions are incompletely understood. The aim of this study was to assess the mechanisms underlying the BP reduction with the SGLT2i dapagliflozin, GLP-1RA exenatide, and dapagliflozin-exenatide compared with placebo in people with obesity and type 2 diabetes.

Methods

Sixty-six people with type 2 diabetes were randomized to 16 weeks of dapagliflozin 10 mg/day, exenatide 10 µg twice daily, dapagliflozin-exenatide, or placebo treatment. The effect of treatments on estimates of: (1) plasma volume (calculated by Strauss formula, bioimpedance spectroscopy, hematocrit, (2) autonomic nervous system activity (heart rate variability), (3) arterial stiffness (pulse wave applanometry), (4) systemic hemodynamic parameters including peripheral vascular resistance, cardiac output and stroke volume (all derived from non-invasively systemic hemodynamic monitoring), and (5) natriuresis (24-hour urine collection) were assessed after 10 days and 16 weeks of treatment.

Results

After 10 days, dapagliflozin reduced systolic BP (SBP) by − 4.7 mmHg, and reduced plasma volume. After 16 weeks, dapagliflozin reduced SBP by − 4.4 mmHg, and reduced sympathetic nervous system (SNS) activity. Exenatide had no effect on SBP, but reduced parasympathetic nervous system activity after 10 days and 16 weeks. After 10 days, dapagliflozin-exenatide reduced SBP by − 4.2 mmHg, and reduced plasma volume. After 16 weeks, dapagliflozin-exenatide reduced SBP by − 6.8 mmHg, and the reduction in plasma volume was still observed, but SNS activity was unaffected.

Conclusions

The dapagliflozin-induced plasma volume contraction may contribute to the initial SBP reduction, while a reduction in SNS activity may contribute to the persistent SBP reduction. Dapagliflozin-exenatide resulted in the largest decrease in SBP. The effect on plasma volume was comparable to dapagliflozin monotherapy, and SNS activity was not reduced, therefore other mechanisms are likely to contribute to the blood pressure lowering effect of this combination, which need further investigation.

Trial registration Clinicaltrials.gov, NCT03361098.

Arterial responses to infusion of glucagon-like peptide-1 in humans: A randomized trial study

Glucagon-like-peptide-1 (GLP-1) is an incretin hormone implicated in several metabolic and neurological disorders. GLP-1 induces vasodilation and increases blood flow in the peripheral circulation. Whether GLP-1 alters cerebral hemodynamics in humans is yet to be elucidated. In a crossover, double-blind, placebo-controlled, and randomized design, 21 healthy volunteers were assigned to receive intravenous GLP-1 infusion (2.5 pmol/kg/min) or placebo over 20 min on two different days separated by at least one week. We used a noninvasive, well-validated transcranial doppler (TCD) and ultrasound dermascan to reveal the effect of GLP-1 on intra- and extracerebral arteries. The mean blood flow velocity in the middle cerebral artery (V_MCA), the diameter of the superficial temporal artery (STA) and radial artery (RA), and facial skin blood flow were measured. In addition, we documented headache and its associated symptoms during and after infusion. Twenty participants were included in the final analysis. We found no difference in the V_MCA (P = 0.227), diameter of the STA (P = 0.096) and the RA (P = 0.221) and facial blood flow (P = 0.814) after GLP-1 compared to placebo. There were no differences in HR, SAT, EtCO₂, or RF (P > 0.05) on the GLP-1 day compared to the placebo day. We found no differences in the incidence of headache after GLP-1 (n = 10) compared to placebo (n = 7) (P = 0.250). GLP-1 infusion did not affect cerebral hemodynamics and induce headache in humans. Further preclinical studies with validated methods are required to determine if intra - and extracerebral vasculature express GLP-1Rs in humans.

Glucagon-like Peptide-1 Receptor Agonists in the Management of Type 2 Diabetes Mellitus and Obesity: The Impact of Pharmacological Properties and Genetic Factors

Glucagon-like peptide-1 (GLP-1) receptor agonists are a new class of antihyperglycemic drugs that enhance appropriate pancreatic β-cell secretion, pancreatic α-cell (glucagon) suppression, decrease liver glucose production, increase satiety through their action on the central nervous system, slow gastric emptying time, and increase insulin action on peripheral tissue. They are effective in the management of type 2 diabetes mellitus and have a favorable effect on weight loss. Their cardiovascular and renal safety has been extensively investigated and confirmed in many clinical trials. Recently, evidence has shown that in addition to the existing approaches for the treatment of obesity, semaglutide in higher doses promotes weight loss and can be used as a drug to treat obesity. However, some T2DM and obese patients do not achieve a desired therapeutic effect of GLP-1 receptor agonists. This could be due to the multifactorial etiologies of T2DM and obesity, but genetic variability in the GLP-1 receptor or signaling pathways also needs to be considered in non-responders to GLP-1 receptor agonists. This review focuses on the pharmacological, clinical, and genetic factors that may influence the response to GLP-1 receptor agonists in the treatment of type 2 diabetes mellitus and obesity.

Effects of GLP-1 receptor agonists on arrhythmias and its subtypes in patients with type 2 diabetes: A systematic review and meta-analysis

PURPOSE

An update of a systematic review and meta-analysis of the risk of arrhythmias and their subtypes in type 2 diabetic patients receiving glucagon-like peptide 1 receptor agonist (GLP-1RA) medication according to data from the Cardiovascular Outcome Trial(CVOT).

METHODS

Randomized controlled trials (RCT) on GLP-1RA therapy and cardiovascular outcomes in type 2 diabetes mellitus patients published in full-text journal databases such as MEDLINE (via PubMed), Embase, Clinical Trials.gov, and the Cochrane Library from establishment to March 1, 2022 were searched. We assessed the quality of individual studies by the Cochrane risk-of-bias algorithm. RevMan 5.4.1 software was use for calculating meta-analysis.

RESULTS

A total of 60,081 randomized participants were included in the data of these 8 GLP-1RA cardiovascular outcomes trials. Pooled analysis reported no significant effect on total arrhythmia [RR=0.96, 95% CI (0.96, 1.05), p =0.36], and its subtypes such as atrial fibrillation [RR=0.96, 95% CI (0.86, 1.07), p =0.43], atrial flutter [RR= 0.82, 95% CI (0.57, 1.19), p =0.30], atrial tachycardia [RR=0.64, 95% CI (0.20, 2.01), p =0.44)], sinoatrial node dysfunction [RR=0.74, 95% CI (0.44, 1.25), p =0.26], ventricular preterm systole [RR=1.42, 95% CI (0.62, 3.26), p =0.41], second degree AV block [RR=0.96, 95% CI (0.53, 1.72), p =0.88], complete AV block [RR=0.75, 95% CI (0.49, 1.17), p =0.21], ventricular fibrillation [RR=1.00, 95% CI (0.50, 2.02), p =1.00], ventricular tachycardia [RR=1.37, 95% CI (0.91, 2.08), p =0.13] from treatment with GLP-1RA versus placebo. However, the risk of hypoglycemia was reduced by about 30% [RR=0.70, 95% CI (0.57, 0.87), p=0.001] and the risk of pneumonia by about 25% [RR=0.85, 95% CI (0.75, 0.97), p=0.01], both statistically significant differences.

CONCLUSION

In type 2 diabetic patients, treatment with GLP-1RA has no significant effect on the risk of major arrhythmias but significantly reduces the risk of hypoglycemia and pneumonia.

Safety of Semaglutide

The glucagon-like peptide-1 receptor agonist (GLP-1RA) semaglutide is the most recently approved agent of this drug class, and the only GLP-1RA currently available as both subcutaneous and oral formulation. While GLP-1RAs effectively improve glycemic control and cause weight loss, potential safety concerns have arisen over the years. For semaglutide, such concerns have been addressed in the extensive phase 3 registration trials including cardiovascular outcome trials for both subcutaneous (SUSTAIN: Semaglutide Unabated Sustainability in Treatment of Type 2 Diabetes) and oral (PIONEER: Peptide InnOvatioN for the Early diabEtes tReatment) semaglutide and are being studied in further trials and registries, including real world data studies. In the current review we discuss the occurrence of adverse events associated with semaglutide focusing on hypoglycemia, gastrointestinal side effects, pancreatic safety (pancreatitis and pancreatic cancer), thyroid cancer, gallbladder events, cardiovascular aspects, acute kidney injury, diabetic retinopathy (DRP) complications and injection-site and allergic reactions and where available, we highlight potential underlying mechanisms. Furthermore, we discuss whether effects are specific for semaglutide or a class effect. We conclude that semaglutide induces mostly mild-to-moderate and transient gastrointestinal disturbances and increases the risk of biliary disease (cholelithiasis). No unexpected safety issues have arisen to date, and the established safety profile for semaglutide is similar to that of other GLP-1RAs where definitive conclusions for pancreatic and thyroid cancer cannot be drawn at this point due to low incidence of these conditions. Due to its potent glucose-lowering effect, patients at risk for deterioration of existing DRP should be carefully monitored if treated with semaglutide, particularly if also treated with insulin. Given the beneficial metabolic and cardiovascular actions of semaglutide, and the low risk for severe adverse events, semaglutide has an overall favorable risk/benefit profile for patient with type 2 diabetes.

Effects of dapagliflozin and gliclazide on the cardiorenal axis in people with type 2 diabetes

OBJECTIVES

There is a bidirectional relationship between cardiovascular and renal disease. The drug-class of SGLT2 inhibitors improves outcomes at both ends of this so called cardiorenal axis. We assessed the effects of SGLT2 inhibition and sulfonylurea treatment on systemic hemodynamic function and investigated whether SGLT2 inhibitor-induced changes in systemic hemodynamics correlate with changes in renal hemodynamics.

METHODS

Forty-four people with type 2 diabetes were randomized to 12 weeks of dapagliflozin 10 mg/day or gliclazide 30 mg/day treatment. Systemic hemodynamic function, autonomic nervous system activity, and vascular stiffness were measured noninvasively, whereas renal hemodynamics, glomerular filtration rate (GFR) and effective renal plasma flow, were assessed with gold-standard urinary clearances of inulin or iohexol and para-aminohippuric acid, respectively. Correlation analyses were performed to assess relationships between dapagliflozin-induced changes in cardiovascular and renal variables.

RESULTS

Dapagliflozin reduced stroke volume by 4%, cardiac output by 5%, vascular stiffness by 11%, and mean arterial pressure by 5% from baseline, without increasing heart rate or sympathetic activity, while simultaneously lowering glomerular filtration rate by 8%. Despite similar improvements in glycemic control by dapagliflozin and gliclazide (-0.5 ± 0.5 versus-0.7 ± 0.5%; P = 0.12), gliclazide did not affect any of these measurements. There was no clear association between the dapagliflozin-induced changes in cardiovascular and renal physiology.

CONCLUSION

Dapagliflozin seemingly influences systemic and renal hemodynamics independently and beyond glucose lowering in people with type 2 diabetes.This clinical trial was registered at https://clinicalTrials.gov (ID: NCT02682563).

The impact of weight loss related to risk of new-onset atrial fibrillation in patients with type 2 diabetes mellitus treated with sodium-glucose cotransporter 2 inhibitor

Background

Sodium–glucose cotransporter 2 inhibitor (SGLT2i) use reduces body weight (BW) in patients with type 2 diabetes mellitus (T2DM). Obesity and T2DM are strong risk factors of new-onset atrial fibrillation (AF). However, whether BW loss following SGLT2i treatment reduces AF risk in patients with T2DM remains unclear.

Methods

We used a medical database from a multicenter health care provider in Taiwan, which included 10,237 patients with T2DM, from June 1, 2016 to December 31, 2018, whose BW data at baseline and at 12 weeks of SGLT2i treatment were available. Patients were followed up from the drug index date until the occurrence of new-onset AF, discontinuation of the SGLT2i, or the end of the study period, whichever occurred first.

Results

The patients’ baseline body mass index (BMI) was 28.08 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\pm$$\end{document}± 4.88 kg/m². SGLT2i treatment was associated with a BW loss of 1.35 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\pm$$\end{document}± 3.28 kg (1.78%\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\pm$$\end{document}± 4.47%). There were 37.4%, 47.0%, and 15.6% of patients experienced no-BW loss (n = 3832), BW loss 0.0–4.9% (n = 4814), and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\ge$$\end{document}≥ 5.0% (n = 1591) following SGLT2i treatment, respectively. Compared with patients with baseline BMI < 23 kg/m², AF risk significantly increased in patients with baseline BMI \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\ge$$\end{document}≥ 27.5 kg/m² (P for trend = 0.015). Compared with those without BW loss after SGLT2i treatment, AF risk significantly decreased with a BW loss of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\ge$$\end{document}≥ 5.0% (adjusted hazard ratios [95% confidence intervals]: 0.39[0.22–0.68]). Use of diuretics, old age, high-dose SGLT2i, higher estimated glomerular filtration rate, and baseline BMI were independent factors associated with a BW loss of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\ge$$\end{document}≥ 5.0% following SGLT2i initiation. By contrast, neither baseline BMI nor BW loss after SGLT2i treatment predicted major cardiovascular adverse events or heart failure hospitalization risk (P for trend > 0.05).

Conclusion

BW loss of ≥ 5.0% following SGLT2i treatment was associated with a lower risk of new-onset AF in patients with T2DM in real-world practice.

Glucagon-Like Peptide-1 (GLP-1) in the Integration of Neural and Endocrine Responses to Stress

Glucagon like-peptide 1 (GLP-1) within the brain is produced by a population of preproglucagon neurons located in the caudal nucleus of the solitary tract. These neurons project to the hypothalamus and another forebrain, hindbrain, and mesolimbic brain areas control the autonomic function, feeding, and the motivation to feed or regulate the stress response and the hypothalamic-pituitary-adrenal axis. GLP-1 receptor (GLP-1R) controls both food intake and feeding behavior (hunger-driven feeding, the hedonic value of food, and food motivation). The activation of GLP-1 receptors involves second messenger pathways and ionic events in the autonomic nervous system, which are very relevant to explain the essential central actions of GLP-1 as neuromodulator coordinating food intake in response to a physiological and stress-related stimulus to maintain homeostasis. Alterations in GLP-1 signaling associated with obesity or chronic stress induce the dysregulation of eating behavior. This review summarized the experimental shreds of evidence from studies using GLP-1R agonists to describe the neural and endocrine integration of stress responses and feeding behavior.

Cardiovascular effects of glucagon-like peptide 1 receptor agonists: from mechanistic studies in humans to clinical outcomes

Type 2 diabetes mellitus (T2DM) is currently one of the most prevalent diseases, with as many as 415 million patients worldwide. T2DM is characterized by elevated blood glucose levels and is often accompanied by several comorbidities, such as cardiovascular disease. Treatment of T2DM is focused on reducing glucose levels by either lifestyle changes or medical treatment. One treatment option for T2DM is based on the gut-derived hormone glucagon-like peptide 1 (GLP-1). GLP-1 reduces blood glucose levels by stimulating insulin secretion, however, it is rapidly degraded, and thereby losing its glycaemic effect. GLP-1 receptor agonists (GLP-1RAs) are immune to degradation, prolonging the glycaemic effect. Lately, GLP-1RAs have spiked the interest of researchers and clinicians due to their beneficial effects on cardiovascular disease. Preclinical and clinical data have demonstrated that GLP-1 receptors are abundantly present in the heart and that stimulation of these receptors by GLP-1 has several effects. In this review, we will discuss the effects of GLP-1RA on heart rate, blood pressure, microvascular function, lipids, and inflammation, as measured in human mechanistic studies, and suggest how these effects may translate into the improved cardiovascular outcomes as demonstrated in several trials.

Glucagon-Like Peptide 1 Receptor Agonists and Heart Failure

With worsening epidemiological trends for both the incidence and prevalence of type 2 diabetes mellitus (T2DM) and heart failure (HF) worldwide, it is critical to implement optimal prevention and treatment strategies for patients with these comorbidities, either alone or concomitantly. Several guidelines and consensus statements have recommended glucagon-like peptide-1 receptor agonists and sodium-glucose cotransporter type 2 inhibitors as add-ons to lifestyle interventions with or without metformin in those at high atherosclerotic cardiovascular disease risk. However, these recommendations are either silent about HF or fail to differentiate between the prevention of HF in those at risk versus the treatment of individuals with manifest HF. Furthermore, these documents do not differentiate among those with different HF phenotypes. This distinction, even though important, may not be critical for sodium-glucose cotransporter type 2 inhibitors in view of the consistent data for benefit for both atherosclerotic cardiovascular disease– and HF-related outcomes that have emerged from the regulatory-mandated cardiovascular outcome trials for all sodium-glucose cotransporter type 2 inhibitors and the recent DAPA-HF trial (Dapagliflozin in Patients with Heart Failure and Reduced Ejection Fraction)demonstrating the benefit of dapagliflozin on HF-related outcomes in patients with HF with reduced ejection fraction with or without T2DM. However, the distinction may be crucial for glucagon-like peptide-1 receptor agonists and other antihyperglycemic agents. Indeed, in several of the new statements, glucagon-like peptide-1 receptor agonists are suggested treatment not only for patients with T2DM and atherosclerotic cardiovascular disease, but also in those with manifest HF, despite a lack of evidence for the latter recommendation. Although glucagon-like peptide-1 receptor agonists may be appropriate to use in patients at risk for HF, mechanistic insights and observations from randomized trials suggest no clear benefit on HF-related outcomes and even uncertainty regarding the safety in those with HF with reduced ejection fraction. Conversely, theoretical rationales suggest that these agents may benefit patients with HF with preserved ejection fraction. Considering that millions of patients with T2DM have HF, these concerns have public health implications that necessitate the thoughtful use of these therapies. Achieving this aim will require dedicated trials with these drugs in both patients who have HF with reduced ejection fraction and HF with preserved ejection fraction with T2DM to assess their efficacy, safety, and risk-benefit profile.

Twelve weeks of exenatide treatment increases [18F]fluorodeoxyglucose uptake by brown adipose tissue without affecting oxidative resting energy expenditure in nondiabetic males

AIMS/HYPOTHESIS

Brown adipose tissue (BAT) improves energy metabolism by combusting glucose and lipids into heat. Agonism of the glucagon-like peptide-1 receptor (GLP-1R) within the central nervous system activates BAT in mice. Moreover, in patients with type 2 diabetes, GLP-1R agonism lowers body weight and improves glucose and lipid levels, possibly involving BAT activation. Interestingly, people from South Asian descent are prone to develop cardiometabolic disease. We studied the effect of GLP-1R agonism on BAT in humans, specifically in South Asians and Europids without obesity or type 2 diabetes.

METHODS

Twelve Dutch South Asian and 12 age- and BMI-matched Europid nondiabetic men received 12 weeks extended-release exenatide (Bydureon) in this single-arm prospective study. Before and after treatment, BAT was visualized by a cold-induced [¹⁸F]FDG-PET/CT scan and a thermoneutral MRI scan, and resting energy expenditure (REE), substrate oxidation, body composition and fasting plasma glucose and serum lipids were determined. Appetite was rated using a visual analogue scale.

RESULTS

Since the effect of exenatide on metabolic parameters did not evidently differ between ethnicities, data of all participants were pooled. Exenatide decreased body weight (-1.5 ± 0.4 kg, p < 0.01), without affecting REE or substrate oxidation, and transiently decreased appetite ratings during the first weeks. Exenatide also lowered triglycerides (-15%, p < 0.05) and total cholesterol (-5%, p < 0.05), and tended to lower glucose levels. Notably, exenatide increased BAT metabolic volume (+28%, p < 0.05) and mean standardized uptake value (+11%, p < 0.05) ([¹⁸F]FDG-PET/CT), without affecting supraclavicular adipose tissue fat fraction (MRI).

CONCLUSIONS/INTERPRETATION

We show for the first time that GLP-1R agonism increases [¹⁸F]FDG uptake by BAT in South Asian and Europid men without obesity or type 2 diabetes.

TRIAL REGISTRY

Clinicaltrials.gov NCT03002675.

Glucagon-like peptide-1 receptors in the kidney: impact on renal autoregulation

Glucagon-like peptide-1 (GLP-1) and strategies based on this blood sugar-reducing and appetite-suppressing hormone are used to treat obesity and type 2 diabetes. However, the GLP-1 receptor (GLP-1R) is also present in the kidney, where it influences renal function. The effect of GLP-1 on the kidney varies between humans and rodents. The effect of GLP-1 on kidney function also seems to vary depending on its concentration and the physiological or pathological state of the kidney. In studies with rodents or humans, acute infusion of pharmacological doses of GLP-1 stimulates natriuresis and diuresis. However, the effect on the renal vasculature is less clear. In rodents, GLP-1 infusion increases renal plasma flow and glomerular filtration rate, suggesting renal vasodilation. In humans, only a subset of the study participants exhibits increased renal plasma flow and glomerular filtration rate. Differential status of kidney function and changes in renal vascular resistance of the preglomerular arterioles may account for the different responses of the human study participants. Because renal function in patients with type 2 diabetes is already at risk or compromised, understanding the effects of GLP-1R activation on kidney function in these patients is particularly important. This review examines the distribution of GLP-1R in the kidney and the effects elicited by GLP-1 or GLP-1R agonists. By integrating results from acute and chronic studies in healthy individuals and patients with type 2 diabetes along with those from rodent studies, we provide insight into how GLP-1R activation affects renal function and autoregulation.

Searching for optimal blood pressure targets in type 2 diabetic patients with coronary artery disease

BACKGROUND

Controversies exist regarding the optimal blood pressure (BP) level that is safe and provides cardiovascular protection in patients with type 2 diabetes mellitus (T2DM) and coexistent coronary artery disease. Several new glucose-lowering agents have been found to lower BP as well, making the interaction between BP and T2DM even more complex.

METHODS

With the reference to recent literature, this review article describes the potential mechanisms of increased risk of hypertension in T2DM and outlines the possible optimal BP levels based upon recommendations on the management of hypertension by the current guidelines, in combination with our research findings, for type 2 diabetic patients with coronary artery disease.

RESULTS

The development of hypertension in T2DM involves multiple processes, including enhanced sympathetic output, inappropriate activation of renin-angiotensin- aldosterone system, endothelial dysfunction induced through insulin resistance, and abnormal sodium handling by the kidney. Both AGE-RAGE axis and adipokine dysregulation activate intracellular signaling pathways, increase oxidative stress, and aggravate vascular inflammation. Pancreatic β-cell specific microRNAs are implicated in gene expression and diabetic complications. Non-pharmacological intervention with lifestyle changes improves BP control, and anti-hypertensive medications with ACEI/ARB, calcium antagonists, β-blockers, diuretics and new hypoglycemic agent SGLT2 inhibitors are effective to decrease mortality and prevent major adverse cardiovascular events. For hypertensive patients with T2DM and stable coronary artery disease, control of BP < 130/80 mmHg but not < 120/70 mmHg is reasonable, whereas for those with chronic total occlusion or acute coronary syndromes, an ideal BP target may be somewhat higher (< 140/90 mmHg). Caution is advised with aggressive lowering of diastolic BP to a critical threshold (< 60 mmHg).

CONCLUSIONS

Hypertension and T2DM share certain similar aspects of pathophysiology, and BP control should be individualized to minimize adverse events and maximize benefits especially for patients with T2DM and coronary artery disease.

Glucagon-like peptide-1 receptor agonists and cardiovascular protection in type 2 diabetes: a pathophysiology-based review of clinical implications

PURPOSE OF REVIEW

Cardiovascular outcome trials (CVOT) with glucagon-like peptide-1 receptor agonists (GLP-1 RA) have had variable results to date: with two CVOTs being positive and two concluding neutrality/safety results for primary cardiovascular outcome. Mechanistic insights delving into the pathophysiologic mechanisms that may link certain GLP-1 RA to cardioprotection may help define the application of this medication class in clinical practice based on the evidence of the CVOT data. We discuss the various mechanisms that have been postulated from animal and preclinical human studies to help explain the benefits observed in CVOTs with GLP-1 RA.

RECENT FINDINGS

Cardiovascular benefits of GLP-1 may be dependent on the complex interactions of this incretin hormone with the atherosclerotic pathways, either through its direct actions on the cardiovascular system or indirectly through intermediary actions on metabolism, energy transfer, inflammation or thrombosis. An indirect metabolic action of GLP-1 RA, via an initial step of achieving glucose homeostasis or balancing inter-organ energy metabolism, leading to favorable downstream effects on the inflammation-thrombosis pathways, finally impacting atherosclerosis, appears compelling.

SUMMARY

In addition to their metabolic benefits, specific GLP-1 RA medications offer cardiovascular protection in high-risk type 2 diabetes. Further mechanistic studies and clinical trials in lower cardiovascular risk populations may help cement the place of this class of medications across the spectrum of type 2 diabetes.

Association of Antihyperglycemic Therapy with Risk of Atrial Fibrillation and Stroke in Diabetic Patients

Type 2 diabetes mellitus (DM) is associated with an increased risk of cardiovascular disease (CVD). Atrial fibrillation (AF) and stroke are both forms of CVD that have major consequences in terms of disabilities and death among patients with diabetes; however, they are less present in the preoccupations of scientific researchers as a primary endpoint of clinical trials. Several publications have found DM to be associated with a higher risk for both AF and stroke; some of the main drugs used for glycemic control have been found to carry either increased, or decreased risks for AF or for stroke in DM patients. Given the risk for thromboembolic cerebrovascular events seen in AF patients, the question arises as to whether stroke and AF occurring with modified incidences in diabetic individuals under therapy with various classes of antihyperglycemic medications are interrelated and should be considered as a whole. At present, the medical literature lacks studies specifically designed to investigate a cause-effect relationship between the incidences of AF and stroke driven by different antidiabetic agents. In default of such proof, we reviewed the existing evidence correlating the major classes of glucose-controlling drugs with their associated risks for AF and stroke; however, supplementary proof is needed to explore a hypothetically causal relationship between these two, both of which display peculiar features in the setting of specific drug therapies for glycemic control.

Heart rate variability in type 2 diabetic subjects randomized to liraglutide or glimepiride treatment, both in combination with metformin: A randomized, open, parallel-group study

AIMS

Reduced heart rate variability (HRV) and increased heart rate (HR) are associated with cardiovascular (CV) mortality. In the Liraglutide Effect and Action in Diabetes outcome trial, it was demonstrated a lower rate of CV events in type 2 diabetes (T2D) patients treated with liraglutide compared to placebo. We aimed to investigate the effects of liraglutide compared with glimepiride treatment in T2D patients on the CV risk parameters HR and HRV.

METHODS

This was a post hoc study whereas sixty-two T2D individuals (45 males) were randomized to once daily 1.8 mg liraglutide or once daily 4 mg glimepiride, both in combination with 1 g metformin. HR and measurement of sympathetic activity, that is standard deviation (SD) of beat-to-beat (NN) intervals (SDNN), was assessed by 24-hour Holter monitoring system. Parasympathetic activity was analysed by root mean square of successive differences (RMSSD) in NN intervals and high-frequency (HF), low-frequency (LF) and very low-frequency power.

RESULTS

Baseline clinical characteristics for liraglutide (n = 33) and glimepiride (n = 29) groups were well matched. There was a persistent increase in diurnal HR followed by a significantly increased HR at daytime 5.4 beats per minute, P = 0.011 in the liraglutide-treated group. There was no treatment change between groups in SDNN and RMSSD, or in HF and LF frequency power analysis.

CONCLUSIONS

Liraglutide treatment increased diurnal variation in hourly mean HR followed by an increase in mean daytime HR, independently of changes in sympathetic or parasympathetic activity.

Update on the Impact, Diagnosis and Management of Cardiovascular Autonomic Neuropathy in Diabetes: What Is Defined, What Is New, and What Is Unmet

The burden of diabetic cardiovascular autonomic neuropathy (CAN) is expected to increase due to the diabetes epidemic and its early and widespread appearance. CAN has a definite prognostic role for mortality and cardiovascular morbidity. Putative mechanisms for this are tachycardia, QT interval prolongation, orthostatic hypotension, reverse dipping, and impaired heart rate variability, while emerging mechanisms like inflammation support the pervasiveness of autonomic dysfunction. Efforts to overcome CAN under-diagnosis are on the table: by promoting screening for symptoms and signs; by simplifying cardiovascular reflex tests; and by selecting the candidates for screening. CAN assessment allows for treatment of its manifestations, cardiovascular risk stratification, and tailoring therapeutic targets. Risk factors for CAN are mainly glycaemic control in type 1 diabetes mellitus (T1DM) and, in addition, hypertension, dyslipidaemia, and obesity in type 2 diabetes mellitus (T2DM), while preliminary data regard glycaemic variability, vitamin B12 and D changes, oxidative stress, inflammation, and genetic biomarkers. Glycaemic control prevents CAN in T1DM, whereas multifactorial intervention might be effective in T2DM. Lifestyle intervention improves autonomic function mostly in pre-diabetes. While there is no conclusive evidence for a disease-modifying therapy, treatment of CAN manifestations is available. The modulation of autonomic function by SGLT2i represents a promising research field with possible clinical relevance.

Exendin-4 Exacerbates Burn-Induced Morbidity in Mice by Activation of the Sympathetic Nervous System

Background

Although glucagon-like peptide 1- (GLP-1-) based therapy of hyperglycemia in burn injury has shown great potential in clinical trials, its safety is seldom evaluated. We hypothesize that exendin-4, a GLP-1 analogue, might affect the immune response via the activation of the sympathetic nervous system in burn injury.

Methods

Male Balb/c mice were subjected to sham or thermal injury of 15% total body surface area. Exendin-4 on T cell function in vitro was examined in cultured splenocytes in the presence of β-adrenoceptor antagonist propranolol (1 nmol/L) or GLP-1R antagonist exendin (9-39) (1 μmol/L), whereas its in vivo effect was determined by i.p. injection of exendin-4 (2.4 nmol/kg) in mice. To further elucidate the sympathetic mechanism, propranolol (30 mg/kg) or vehicle was applied 30 min prior to injury.

Results

Although the exacerbated burn-induced mortality by exendin-4 was worsened by propranolol pretreatment, the inhibition of T cell proliferation by exendin-4 in vitro could be restored by propranolol instead of exendin (9-39). However, a Th2 switch by exendin-4 in vitro could only be reversed by exendin (9-39). Likewise, the inhibition of splenic T cell function and NFAT activity by exendin-4 in vivo was restored by propranolol. By contrast, the increased splenic NF-κB translocation by exendin-4 in vivo was potentiated by propranolol in sham mice but suppressed in burn mice. Accordingly, propranolol abrogated the heightened inflammatory response in the lung and the accelerated organ injuries by exendin-4 in burn mice. On the contrary, a Th2 switch and higher serum levels of inflammatory mediators by exendin-4 were potentiated by propranolol in burn mice. Lastly, exendin-4 raised serum stress hormones which could be remarkably augmented by propranolol.

Conclusions

Exendin-4 suppresses T cell function and promotes organ inflammation through the activation of the sympathetic nervous system, while elicits Th2 switch via GLP-1R in burn injury.

A Drug Repurposing Method Based on Drug-Drug Interaction Networks and Using Energy Model Layouts

Complex network representations of reported drug-drug interactions foster computational strategies that can infer pharmacological functions which, in turn, create incentives for drug repositioning. Here, we use Gephi (a platform for complex network visualization and analysis) to represent a drug-drug interaction network with drug interaction information from DrugBank 4.1. Both modularity class- and force-directed layout ForceAtlas2 are employed to generate drug clusters which correspond to nine specific drug properties. Most drugs comply with their cluster's dominant property; however, some of them seem not to be in a proper position (i.e., in accordance with their already known functions). Such cases, along with cases of drugs that are topologically placed in the overlapping or bordering zones between clusters, may indicate previously unaccounted pharmacologic functions, thus leading to potential repositionings. Out of the 1141 drugs with relevant information on their interactions in DrugBank 4.1, we confirm the predicted properties for 85% of the drugs. The high prediction rate of our methodology suggests that, at least for some of the 15% drugs that seem to be inconsistent with the predicted property, we can get very good repositioning hints. As such, we present illustrative examples of recovered well-known repositionings, as well as recently confirmed pharmacological properties.

Different mechanisms involved in liraglutide and glucagon-like peptide-1 vasodilatation in rat mesenteric small arteries

BACKGROUND AND PURPOSE

Glucagon-like peptide-1 (GLP-1) is an incretin hormone that regulates insulin biosynthesis and secretion in a glucose-dependent manner and has been reported to induce vasodilatation. Here, we examined the possible vasorelaxant effect of GLP-1 and its underlying mechanisms.

EXPERIMENTAL APPROACH

Rat mesenteric arteries (diameter ≈ 200-400 μm) and human s.c. arteries were mounted in microvascular myographs for isometric tension recordings. The effect of GLP-1 on vascular responses was examined under normoglycaemic conditions and at high glucose concentrations.

KEY RESULTS

In rat mesenteric arteries and human s.c. arteries without branches, physiological concentrations (1-100 nM) of GLP-1(7-36) and liraglutide failed to cause relaxation or affect contractions evoked by electrical field stimulation. In contrast to GLP-1(7-36), liraglutide induced relaxations antagonized by the GLP-1 receptor antagonist, exendin-(9-39), in branched mesenteric arteries. In contrast to liraglutide, GLP-1 leftward shifted the concentration relaxation curves for bradykinin in s.c. arteries from patients with peripheral arterial disease, an effect resistant to exendin-(9-39). Under normoglycaemic conditions, neither GLP-1 nor liraglutide affected ACh relaxation in rat mesenteric arteries. In arteries exposed to 40 mM glucose, GLP-1, in contrast to liraglutide, potentiated ACh-induced relaxation by a mechanism that was not antagonized by exendin-(9-39). GLP-1 decreased superoxide levels measured with dihydroethidium in rat mesenteric arteries exposed to 40 mM glucose.

CONCLUSIONS AND IMPLICATIONS

GLP-1 receptors are involved in the liraglutide-induced relaxation of branched arteries, under normoglycaemic conditions, while GLP-1 inhibition of vascular superoxide levels contributes to GLP-1 receptor-independent potentiation of endothelium-dependent vasodilatation in hyperglycaemia.

Lixisenatide Versus Insulin Glulisine on Fasting and Postbreakfast Systemic Hemodynamics in Type 2 Diabetes Mellitus Patients

The prolonged treatment effects of a short-acting GLP-1RA (glucagon-like peptide-1 receptor agonist), such as lixisenatide, on fasting and postprandial systemic hemodynamics in type 2 diabetes mellitus patients are unknown. In this secondary analysis, we included 34 overweight insulin glargine-treated type 2 diabetes mellitus patients (mean±SD age, 62±7 years; HbA_1c, 8.0±0.9%; systolic blood pressure [BP], 133.9±16.1 mm Hg; diastolic BP, 75.4±8.39 mm Hg) that were randomized to once-daily lixisenatide 20 μg or once-daily titrated insulin glulisine for 8 weeks. Systemic hemodynamics (oscillometric device and finger photoplethysmography), arterial stiffness (applanation tonometry), and cardiac sympathovagal balance (heart rate variability) were measured in the fasting state and repetitively (up to minute 175) after a standardized mixed breakfast. Acetaminophen was given orally to estimate gastric emptying rate. Lixisenatide did not affect fasting systemic hemodynamics compared with insulin glulisine from baseline to week 8. Postbreakfast overall, lixisenatide compared with insulin glulisine tended to increase systolic BP by 5.2±2.9 mm Hg (P=0.087) and increased diastolic BP by 5.4±1.4 mm Hg (P<0.001), with respective maximal differences of +10.2±3.7 mm Hg (P=0.007) and +7.2±1.5 mm Hg (P<0.001). Lixisenatide increased systemic vascular resistance (P<0.001) and arterial stiffness (P=0.007). No between-group differences in overall postbreakfast heart rate, cardiac output, or cardiac sympathovagal balance, and circulating catecholamines, angiotensin II, or aldosterone were observed. Both treatments lowered HbA_1c similarly, whereas lixisenatide achieved greater reductions in postbreakfast plasma glucose excursions. Lixisenatide slowed gastric emptying rate, which statistically explained changes in postbreakfast BP. Lixisenatide compared with once-daily titrated insulin glulisine for 8 weeks does not affect fasting but increases postbreakfast BP in insulin glargine-treated type 2 diabetes mellitus patients. This effect could, at least in part, be explained by reduced passage rate of nutrients and water and activation of the gastrovascular reflex.

Changes in Heart Rate Associated with Exenatide Once Weekly: Pooled Analysis of Clinical Data in Patients with Type 2 Diabetes

INTRODUCTION

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) improve glycemia in patients with type 2 diabetes, but heart rate increases have been observed.

METHODS

A pooled post hoc analysis of 11 randomized clinical trials (N = 4595) of 10-30 weeks' duration from the exenatide once-weekly (QW) development program evaluated heart rate with exenatide QW (intervention group) and exenatide twice daily (BID), liraglutide, and non-GLP-1RAs (insulin, metformin, pioglitazone, and sitagliptin) (comparison groups). The time course and size of heart rate changes from baseline and the relationship of heart rate change with baseline heart rate were studied. A multivariate analysis (9 studies; N = 3903) examined associations between patient characteristics or treatments and heart rate increases.

RESULTS

Mean baseline heart rate ± standard deviation was 75.0 ± 8.5 beats per minute (bpm) with exenatide QW (n = 2096), 75.8 ± 8.7 bpm with exenatide BID (n = 606), 75.2 ± 8.9 bpm with liraglutide (n = 450), and 74.5 ± 8.6 bpm with non-GLP-1RAs (n = 1443). Least-squares mean ± standard error changes from baseline to final heart rate were + 2.7 ± 0.2, + 1.0 ± 0.3, and + 3.0 ± 0.4 bpm with exenatide QW, exenatide BID, and liraglutide, respectively, and - 0.8 ± 0.2 bpm with non-GLP-1RAs. The size and direction of heart rate changes in individual patients varied within each treatment group at all time points. At posttreatment follow-up, heart rate reverted to the baseline level after GLP-1RA discontinuation. Heart rate changes correlated negatively with baseline heart rate for all therapies (r = - 0.3 to - 0.4). Baseline heart rate was the strongest predictor of increased heart rate.

CONCLUSIONS

Small increases in heart rate were associated with exenatide QW, exenatide BID, and liraglutide treatments but reverted to baseline after discontinuation. Increases were more likely in patients with a low baseline heart rate. The clinical relevance of these heart rate increases is unknown but will be clarified by several ongoing and recently completed cardiovascular outcome studies.

Augmentation of glucagon-like peptide-1 receptor signalling by neprilysin inhibition: potential implications for patients with heart failure

Augmentation of glucagon-like peptide-1 (GLP-1) receptor signalling is an established approach to the treatment of type 2 diabetes. However, endogenous GLP-1 and long-acting GLP-1 receptor analogues are degraded not only by dipeptidyl peptidase-4, but also by neprilysin. This observation raises the possibilities that endogenous GLP-1 contributes to the clinical effects of neprilysin inhibition and that patients concurrently treated with sacubitril/valsartan and incretin-based drugs may experience important drug-drug interactions. Specifically, potentiation of GLP-1 receptor signalling may underlie the antihyperglycaemic actions of sacubitril/valsartan. Neprilysin inhibitors may also be able to augment the effects of long-acting GLP-1 analogues to increase heart rate and myocardial cyclic AMP, and thus, potentiate these deleterious actions; if so, concomitant treatment with GLP-1 receptor agonists may limit the efficacy of neprilysin inhibitors in patients with both heart failure and diabetes. For patients not concurrently treated with GLP-1 analogues, the action of neprilysin to enhance the effects of GLP-1 may be particularly relevant in the brain, where augmentation of GLP-1 and other endogenous peptides may act to inhibit amyloid-induced neuroinflammation and cytotoxicity and improve memory formation and executive functioning. Experimentally, neprilysin inhibitors may also potentiate the effects of endogenous GLP-1 and GLP-1 receptor agonists on blood vessels and the kidney. The role of neprilysin in the metabolism of endogenous GLP-1 and long-acting GLP-1 analogues points to a range of potential pathophysiological effects that may be clinically relevant to patients with heart failure, with or without diabetes.

Postprandial renal haemodynamic effect of lixisenatide vs once-daily insulin-glulisine in patients with type 2 diabetes on insulin-glargine: An 8-week, randomised, open-label trial

AIM

To determine whether lixisenatide, a prandial short-acting glucagon-like peptide receptor agonist (GLP-1RA), ameliorates postprandial glomerular hyperfiltration in patients with type 2 diabetes mellitus (T2DM) compared with insulin-glulisine (iGlu).

METHODS

Postprandial renal haemodynamic effects of 8-week treatment with lixisenatide 20 µg vs once-daily titrated iGlu were measured in 35 overweight patients with T2DM inadequately controlled on insulin-glargine, with or without metformin [mean ± SD age 62 ± 7 years, HbA1c 8.0% ± 0.9%, estimated glomerular filtration rate (GFR) 85 ± 12 mL/min/1.73 m² , median (IQR) urinary albumin/creatinine ratio 1.5 (0.9-3.0) mg/mmol]. After a standardised breakfast, GFR (primary endpoint) and effective renal plasma flow (ERPF) were determined by inulin and para-aminohippuric acid renal clearance, respectively, based on timed urine sampling. Intrarenal haemodynamic functions were estimated using Gomez equations.

RESULTS

Compared with iGlu, lixisenatide did not affect GFR [+0.1 mL/min/1.73 m² (95% CI -9 to 9)], ERPF [-17 mL/min/1.73 m² (-61 to 26)], other (intra-)renal haemodynamics or renal damage markers, but increased fractional sodium excretion [+0.25% (0.09-0.41)] and urinary pH [+0.7 (0.3-1.2)]. Plasma renin, angiotensin-II and aldosterone were unchanged. Lixisenatide and iGlu reduced HbA1c similarly, by 0.8% ± 0.1% and 0.6% ± 0.1%, respectively, while postprandial glucose was lower with lixisenatide (P = .002). Compared with iGlu, lixisenatide reduced bodyweight [-1.4 kg (-2.5 to -0.2)] and increased postprandial mean arterial pressure [+9 mm Hg (4-14)].

CONCLUSION

Eight-week lixisenatide treatment does not affect postprandial (intra-)renal haemodynamics compared with iGlu when added to insulin-glargine in patients with T2DM without overt nephropathy. Prolonged lixisenatide treatment has a sustained natriuretic effect, which is in contrast to previous reports on long-acting GLP-1RA, reduces body weight and increases postprandial blood pressure compared with iGlu.

TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT02276196.

Long-Acting GLP-1 Receptor Agonist Exenatide Influence on the Autonomic Cardiac Sympatho-Vagal Balance

Long-acting glucagon-like peptide 1 receptor agonists are increasingly used to treat type 2 diabetes. An increase of heart rate (HR) has been observed with their use. To elucidate the role of the cardiac sympatho-vagal balance as a possible mediator of the reported increase in HR, we performed power spectral analysis of HR variability (HRV) in patients receiving exenatide extended-release (ER). Twenty-eight ambulatory patients with type 2 diabetes underwent evaluation at initiation of exenatide-ER and thereafter at 3 and at 6 months. To obtain spectral analyses of HRV, a computerized acquisition of 10 minutes of RR electrocardiogram intervals (mean values of ~700 RR intervals) were recorded both in lying and in standing positions. All patients showed a substantial increase of HR both in lying and in standing positions. Systolic blood pressure, body weight, and glycated hemoglobin A1c significantly decreased both at 3 and 6 months compared with basal levels. The low-frequency/high-frequency ratio varied from 3.05 ± 0.4 to 1.64 ± 0.2 (P < 0.001) after 3 months and to 1.57 ± 0.3 (P < 0.001) after 6 months in a lying position and from 4.56 ± 0.8 to 2.24 ± 0.3 (P < 0.001) after 3 months and to 2.38 ± 0.4 (P < 0.001) after 6 months in a standing position compared with basal values, respectively. HR variations, induced by exenatide-ER treatment, do not appear to be related to sympathetic autonomic tone. Of note, we observed a relative increase of vagal influence on the heart.

Glucagon-like peptide-1 receptor agonists and atrial fibrillation: a systematic review and meta-analysis of randomised controlled trials

BACKGROUND

The pharmacological stimulation of GLP-1 receptors is associated with an increase in heart rate. A pooled analysis of patient-level data from phase III trials with albiglutide revealed a significant increase in the risk of atrial fibrillation. Aim of the present meta-analysis is to summarize all available evidence on the effects of individual GLP-1 receptor agonists (RA), and of the whole class, on the incidence of atrial fibrillation.

METHODS

A Medline search for GLP-1 RA (exenatide, liraglutide, lixisenatide, albiglutide, dulaglutide, or semaglutide) was performed, collecting all randomized clinical trials with a duration ≥12 weeks, enrolling patients with type 2 diabetes and comparing a GLP-1 RA with placebo or any other non-GLP-1 RA drug.

RESULTS

Of the 113 trials fulfilling the inclusion criteria, 19 did not report information on atrial fibrillation, whereas 63 reported zero events in all treatment groups. In the remaining trials (enrolling 17,966 and 15,305 patients in GLP-1 RA and comparator arms, respectively, 55.3% women, with a mean age of 57.0 ± 3.8 years), treatment with GLP-1 RA was not associated with a significant increase in the incidence of atrial fibrillation [Mantel-Haenszel OR (95% CI) 0.87 (0.71-1.05), p = 0.15].

CONCLUSIONS

In conclusion, available data suggest that GLP-1 RA is not associated with atrial fibrillation, with the only possible exception of albiglutide. Newly onset atrial fibrillation deserves to be investigated as an event of special interest in future trials with GLP-1 RA.

Cardiovascular Actions and Clinical Outcomes With Glucagon-Like Peptide-1 Receptor Agonists and Dipeptidyl Peptidase-4 Inhibitors

Potentiation of glucagon-like peptide-1 (GLP-1) action through selective GLP-1 receptor (GLP-1R) agonism or by prevention of enzymatic degradation by inhibition of dipeptidyl peptidase-4 (DPP-4) promotes glycemic reduction for the treatment of type 2 diabetes mellitus by glucose-dependent control of insulin and glucagon secretion. GLP-1R agonists also decelerate gastric emptying, reduce body weight by reduction of food intake and lower circulating lipoproteins, inflammation, and systolic blood pressure. Preclinical studies demonstrate that both GLP-1R agonists and DPP-4 inhibitors exhibit cardioprotective actions in animal models of myocardial ischemia and ventricular dysfunction through incompletely characterized mechanisms. The results of cardiovascular outcome trials in human subjects with type 2 diabetes mellitus and increased cardiovascular risk have demonstrated a cardiovascular benefit (significant reduction in time to first major adverse cardiovascular event) with the GLP-1R agonists liraglutide (LEADER trial [Liraglutide Effect and Action in Diabetes: Evaluation of Cardiovascular Ourcome Results], -13%) and semaglutide (SUSTAIN-6 trial [Trial to Evaluate Cardiovascular and Other Long-term Outcomes with Semaglutide], -24%). In contrast, cardiovascular outcome trials examining the safety of the shorter-acting GLP-1R agonist lixisenatide (ELIXA trial [Evaluation of Lixisenatide in Acute Coronary Syndrom]) and the DPP-4 inhibitors saxagliptin (SAVOR-TIMI 53 trial [Saxagliptin Assessment of Vascular Outcomes Recorded in Patients With Diabetes Mellitus-Thrombolysis in Myocardial Infarction 53]), alogliptin (EXAMINE trial [Examination of Cardiovascular Outcomes With Alogliptin Versus Standard of Care in Patients With Type 2 Diabetes Mellitus and Acute Coronary Syndrome]), and sitagliptin (TECOS [Trial Evaluating Cardiovascular Outcomes With Sitagliptin]) found that these agents neither increased nor decreased cardiovascular events. Here we review the cardiovascular actions of GLP-1R agonists and DPP-4 inhibitors, with a focus on the translation of mechanisms derived from preclinical studies to complementary findings in clinical studies. We highlight areas of uncertainty requiring more careful scrutiny in ongoing basic science and clinical studies. As newer more potent GLP-1R agonists and coagonists are being developed for the treatment of type 2 diabetes mellitus, obesity, and nonalcoholic steatohepatitis, the delineation of the potential mechanisms that underlie the cardiovascular benefit and safety of these agents have immediate relevance for the prevention and treatment of cardiovascular disease.

Treatment Strategy for Type 2 Diabetes with Obesity: Focus on Glucagon-like Peptide-1 Receptor Agonists

PURPOSE

The progressive nature of type 2 diabetes mellitus (T2DM) calls for step-wise intensification of therapy for maintaining normal glycemic levels and lowering cardiovascular (CV) risk. Because obesity is a prominent risk factor and comorbidity of T2DM, it further elevates the CV risk in T2DM. Therefore, it is vital to manage weight, obesity, and glycemic parameters for effective T2DM management. Few oral antidiabetic drugs (sulfonylureas and thiazolidinediones) and insulin are not suitable for obese patients with T2DM because these drugs cause weight gain. The present review discusses the place of glucagon-like peptide-1 receptor agonists (GLP-1RAs) in the treatment of obese patients with T2DM and the significance of these drugs in the prevention of future CV risk in patients with T2DM.

METHODS

A literature search of PubMed and EMBASE was conducted by using the search terms T2DM, GLP-1RAs, obesity, and cardiovascular complication. Randomized controlled trials measuring the effect of GLP-1RAs versus that of placebo on CV outcomes were included in the review.

FINDINGS

GLP-1RAs have emerged as a therapeutic alternative; these drugs exert their actions by providing glycemic control, improving insulin resistance and ö̇-cell function, and reducing weight. The risk of hypoglycemia with GLP-1RAs is minimal; however, GLP-1RAs are associated with gastrointestinal adverse events and raise concerns regarding pancreatitis. Combining GLP-1RAs with insulin analogues results in higher efficacy, a lowered insulin dose, and reduced insulin-related hypoglycemia and weight gain. Longer acting GLP-1RAs are also associated with improvement in medication adherence. Improvement in CV risk factors such as blood pressure and lipid profile further increases their usability for improving CV outcomes.

IMPLICATIONS

Overall, the properties of GLP-1RAs make them suitable for combination with oral antidiabetic drugs in the early stages of T2DM and with insulins in the later stages for optimizing comprehensive management of the disease.

Albiglutide for the treatment of type 2 diabetes mellitus: An integrated safety analysis of the HARMONY phase 3 trials

AIMS

Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) stimulate the incretin system and lower glycaemic parameters in type 2 diabetes mellitus (T2DM). This analysis of clinical studies of up to 3years evaluated the safety of albiglutide, a GLP-1 RA, in people with T2DM.

METHODS

Integrated safety analysis included seven phase-3 T2DM studies of albiglutide compared with placebo and/or active comparators (a dipeptidyl peptidase-4 inhibitor, GLP-1 RA, insulin, sulphonylurea, and thiazolidinedione).

RESULTS

Studies of 32months (HARMONY 7), 1year (HARMONY 6), and 3years (HARMONY 1-5), reported similar rates of adverse events (AEs) (84.8%, 82.3%), and serious AEs (13.1%, 12.9%) between albiglutide and all comparators, respectively. AEs that did not differ between the groups included symptomatic or severe hypoglycaemia as well as nausea (12.0%, 11.3%) and vomiting (5.3%, 4.7%) for albiglutide and all comparators, respectively. According to the Medical Dictionary for Regulatory Activities preferred terms, only diarrhoea (13.7%, 9.9%), injection-site reaction (9.0%, 2.0%), and peripheral oedema (4.5%, 6.8%) had at least 2% difference between the albiglutide and all-comparator groups. In a similar integrated analysis, pancreatitis occurred more often with albiglutide (0.3%, 0.1%). Renal and cardiac function did not differ between the two groups.

CONCLUSIONS

In an integrated analysis of seven phase 3 clinical trials, albiglutide-treated patients experienced frequencies of AEs (including cardiovascular and renal) similar to the all-comparators group treated with other T2DM medications or placebo. Albiglutide treatment was associated with higher rates of diarrhoea and injection-site reactions, but not increased nausea and vomiting, versus all comparators.

The effects of GLP-1 based therapies on postprandial haemodynamics: Two randomised, placebo-controlled trials in overweight type 2 diabetes patients

AIMS

To assess the effects of glucagon-like peptide (GLP)-1 receptor agonists and dipeptidyl peptidase (DPP)-4 inhibitors on postprandial haemodynamics.

METHODS

57 patients with type 2 diabetes (mean±SD age 62.8±6.9years; BMI 31.8±4.1kg/m²; HbA_1c 7.3±0.6%) were included in an acute (exenatide- or placebo-infusion) and 12-week (liraglutide, sitagliptin or placebo) randomised, placebo-controlled, double-blind trial. Systemic haemodynamics (oscillometric technique and finger photoplethysmography), vascular stiffness (tonometry), and sympathetic nervous system (SNS)-activity (heart rate variability) were determined in the fasting state and following a standardised mixed meal.

RESULTS

In both studies, postprandial blood pressure (BP) decreased during placebo-intervention. Compared with placebo, acute exenatide-infusion increased postprandial diastolic BP (6.7 [95%-confidence interval 3.6-9.9]mmHg, p<0.001) and vascular resistance (683.6 [438.5-928.8]dyn*s/cm⁵/1.73m², p<0.001), while cardiac index decreased (0.6 [0.40.8]L/min/1.73m²; p<0.001). Systolic BP, augmentation index and SNS-activity were unaffected. Twelve-week liraglutide-treatment did not affect postprandial haemodynamics, while sitagliptin decreased diastolic BP (3.5 [0.0-6.9] mmHg; p=0.050), vascular resistance (309.9 [66.6-553.1]dyn*s/cm⁵/1.73m²; p=0.013) and cardiac index (0.3 [0.0-0.6]L/min/1.73m²; p=0.040), compared with placebo. Neither liraglutide nor sitagliptin affected SNS-activity or augmentation index. All treatments significantly lowered postprandial glucose levels.

CONCLUSIONS

Acute exenatide-infusion prevented the meal-induced decline in diastolic BP, although prolonged liraglutide intervention did not affect postprandial haemodynamics. The meal-induced drop in BP was augmented during sitagliptin-treatment.

Blood pressure control in type 2 diabetic patients

Diabetes mellitus (DM) and essential hypertension are common conditions that are frequently present together. Both are considered risk factors for cardiovascular disease and microvascular complications and therefore treatment of both conditions is essential. Many papers were published on blood pressure (BP) targets in diabetic patients, including several works published in the last 2 years. As a result, guidelines differ in their recommendations on BP targets in diabetic patients. The method by which to control hypertension, whether pharmacological or non-pharmacological, is also a matter of debate and has been extensively studied in the literature. In recent years, new medications were introduced for the treatment of DM, some of which also affect BP and the clinician treating hypertensive and diabetic patients should be familiar with these medications and their effect on BP. In this manuscript, we discuss the evidence supporting different BP targets in diabetics and review the various guidelines on this topic. In addition, we discuss the various options available for the treatment of hypertension in diabetics and the recommendations for a specific treatment over the other. Finally we briefly discuss the new diabetic drug classes and their influence on BP.

Effects of Liraglutide on Heart Rate and Heart Rate Variability: A Randomized, Double-Blind, Placebo-Controlled Crossover Study

OBJECTIVE

Reduced heart rate variability (HRV) and increased heart rate (HR) have been associated with cardiovascular mortality. Glucagon-like peptide 1 receptor agonists (GLP-1 RAs) increase HR, and studies have suggested that they may reduce HRV. We examined the effect of the GLP-1 RA liraglutide on HRV and diurnal variation of HR in overweight patients with newly diagnosed type 2 diabetes (T2D) and stable coronary artery disease (CAD).

RESEARCH DESIGN AND METHODS

Liraglutide or placebo was administrated to a backbone therapy of metformin in this double-blind, placebo-controlled 12 + 12-week crossover study. SD of beat-to-beat (NN) intervals (SDNN) was assessed by 24-h Holter monitoring as a measure of HRV. Diurnal HR variation and sympathovagal balance analyzed by root mean square of successive differences (RMSSD) in NN intervals and high-frequency (HF) and low-frequency (LF) power were assessed.

RESULTS

Compared with placebo, liraglutide decreased SDNN in 27 subjects (-33.9 ms; P < 0.001, paired analysis); decreased RMSSD (-0.3 log-ms; P = 0.025); and increased the mean HR (8.1 beats/min; P = 0.003), daytime HR (5.7; P = 0.083), and nighttime HR (6.3; P = 0.026). In a multivariable regression analysis, the decrease in SDNN remained significant after adjustment for metabolic and HR changes. Liraglutide reduced HF power (-0.7 log-ms²; P = 0.026) without any change in LF/HF ratio.

CONCLUSIONS

In overweight patients with CAD and newly diagnosed T2D, liraglutide increased HR and reduced HRV despite significant weight loss and improvement in metabolic parameters. The increase in nightly HR in conjunction with a decrease in parameters of parasympathetic activity suggests that liraglutide may affect sympathovagal balance.

Heart rate acceleration with GLP-1 receptor agonists in type 2 diabetes patients: an acute and 12-week randomised, double-blind, placebo-controlled trial

OBJECTIVE

To examine mechanisms underlying resting heart rate (RHR) increments of GLP-1 receptor agonists in type 2 diabetes patients.

DESIGN

Acute and 12-week randomised, placebo-controlled, double-blind, single-centre, parallel-group trial.

METHODS

In total, 57 type 2 diabetes patients (mean ± s.d. age: 62.8 ± 6.9 years; BMI: 31.8 ± 4.1 kg/m²; HbA1c: 7.3 ± 0.6%), treated with metformin and/or sulfonylureas, were included between July 2013 and August 2015. In the acute study, the GLP-1 receptor agonist exenatide (n = 29) or placebo (saline 0.9%; n = 28) was infused intravenously. Subsequently, patients were again randomised to receive the GLP-1 receptor agonist liraglutide (n = 19) or matching placebo (n = 17) for 12 weeks. RHR and blood pressure (BP) were measured by oscillometric technique, systemic haemodynamics by finger photoplethysmography, sympathetic nervous system (SNS) activity by heart rate variability and arterial stiffness by applanation tonometry. This trial was registered at ClinicalTrials.gov (Nbib1744236).

RESULTS

Exenatide-infusion increased RHR (mean ± s.e.m. +7.5 ± 0.9 BPM, P < 0.001), and systolic and diastolic BP (both P < 0.05), compared with placebo. Vascular resistance increased during exenatide-infusion, whereas stroke volume and arterial stiffness decreased (P < 0.05). SNS activity and cardiac output were unaffected. Twelve-week treatment with liraglutide increased RHR (+6.6 ± 2.1 BPM), while reducing systolic BP (-12.6 ± 4.7 mmHg) and stroke volume (all P < 0.01). Cardiac output, vascular resistance, arterial stiffness and SNS activity remained unchanged (all P > 0.05).

CONCLUSIONS

RHR acceleration with acute and 12-week GLP-1 receptor agonist treatment in type 2 diabetes patients is not explained by changes in SNS activity, and our data argue against vasodilation. In line with pre-clinical data, direct sino-atrial stimulation may be involved.

Safety and tolerability of glucagon-like peptide-1 receptor agonists: unresolved and emerging issues

INTRODUCTION

Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are a mainstay of treatment options for type 2 diabetes. They contribute to lowering blood glucose levels, generally have a favorable tolerability profile, and can be used alone or in combination with other antidiabetic agents. Based on the duration of their effects, GLP-1 RAs can be divided into two classes: short-acting and long-acting. Differences exist between these sub-classes, and between each drug, in terms of pharmacokinetic and pharmacodynamic profiles. Therefore, prescribers cannot necessarily assume GLP-1 RA 'class effects', especially in terms of tolerability. Areas covered: This article reviews the published data on the safety and tolerability of currently available GLP-1 RAs and, recognizing the importance of safety profiles when selecting the appropriate treatment for each patient, examines the clinical implications of the differences between the drugs in this class. Cardiovascular safety, gastrointestinal tolerability, and tolerability in elderly patients are discussed as specific areas of interest to prescribers selecting between GLP-1 RAs for their patients. Expert opinion: Although further research is needed, the current evidence offers the potential to tailor treatment more accurately to each patient. Ultimately, this may improve adherence and persistence, thereby improving glycemic control and, in turn, reducing the risk of macro- and micro-vascular complications.

The physiological role of the brain GLP-1 system in stress

Glucagon-like peptide-1 (GLP-1) within the brain is a potent regulator of food intake and most studies have investigated the anorexic effects of central GLP-1. A range of brain regions have now been found to be involved in GLP-1 mediated anorexia, including some which are not traditionally associated with appetite regulation. However, a change in food intake can be indicative of not only reduced energy demand, but also changes in the organism’s motivation to eat following stressful stimuli. In fact, acute stress is well-known to reduce food intake. Recently, more research has focused on the role of GLP-1 in stress and the central GLP-1 system has been found to be activated in response to stressful stimuli. The source of GLP-1 within the brain, the preproglucagon (PPG) neurons, are ideally situated in the brainstem to receive and relay signals of stress and our recent data on the projection pattern of the PPG neurons to the spinal cord suggest a potential strong link with the sympathetic nervous system. We review here the role of central GLP-1 in the regulation of stress responses and discuss the potential involvement of the endogenous source of GLP-1 within the brain, the PPG neurons.

Acute renal effects of the GLP-1 receptor agonist exenatide in overweight type 2 diabetes patients: a randomised, double-blind, placebo-controlled trial

AIMS/HYPOTHESIS

This study aimed to investigate the acute renal effects of the glucagon-like peptide-1 receptor agonist (GLP-1RA) exenatide in type 2 diabetes patients.

METHODS

We included overweight (BMI 25-40 kg/m(2)) men and postmenopausal women, aged 35-75 years with type 2 diabetes (HbA1c 48-75 mmol/mol; 6.5-9.0%) and estimated GFR ≥ 60 ml min(-1) 1.73 m(-2). Exenatide or placebo (NaCl solution, 154 mmol/l) was administrated intravenously in an acute, randomised, double-blind, placebo-controlled trial conducted at the Diabetes Center VU University Medical Center (VUMC). GFR (primary endpoint) and effective renal plasma flow (ERPF) were determined by inulin and para-aminohippurate clearance, respectively, based on timed urine sampling. Filtration fraction (FF) and effective renal vascular resistance (ERVR) were calculated, and glomerular hydrostatic pressure (PGLO) and vascular resistance of the afferent (RA) and efferent (RE) renal arteriole were estimated. Tubular function was assessed by absolute and fractional excretion of sodium (FENa), potassium (FEK) and urea (FEU), in addition to urine osmolality, pH and free water clearance. Renal damage markers, BP and plasma glucose were also determined.

RESULTS

Of the 57 patients randomised by computer, 52 were included in the final analyses. Exenatide (n = 24) did not affect GFR (mean difference +2 ± 3 ml min(-1) 1.73 m(-2), p = 0.489), ERPF, FF, ERVR or PGLO, compared with placebo (n = 28). Exenatide increased RA (p < 0.05), but did not change RE. Exenatide increased FENa, FEK, urine osmolality and pH, while FEU, urinary flow and free water clearance were decreased (all p < 0.05). Osmolar clearance and renal damage makers were not affected. Diastolic BP and mean arterial pressure increased by 3 ± 1 and 6 ± 2 mmHg, respectively, whereas plasma glucose decreased by 1.4 ± 0.1 mmol/l (all p < 0.05).

CONCLUSIONS/INTERPRETATION

Exenatide infusion does not acutely affect renal haemodynamics in overweight type 2 diabetes patients at normal filtration levels. Furthermore, acute GLP-1RA administration increases proximal sodium excretion in these patients.

TRIAL REGISTRATION

ClincialTrials.gov NCT01744236 FUNDING : The research leading to these results has been funded from: (1) the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement number 282521 - the SAFEGUARD project; and (2) the Dutch Kidney Foundation, under grant agreement IP12.87.

Cardiovascular Effects of Glucagon-Like Peptide-1 Receptor Agonists

Glucagon-like peptide-1 (GLP-1) is a member of the proglucagon incretin family, and GLP-1 receptor agonists (RAs) have been introduced as a new class of antidiabetic medications in the past decade. The benefits of GLP-1 RAs are derived from their pleiotropic effects, which include glucose-dependent insulin secretion, suppressed glucagon secretion, and reduced appetite. Moreover, GLP-1 RAs also exert beneficial roles on multiple organ systems in which the GLP-1 receptors exist, including the cardiovascular system. Cardiovascular effects of GLP-1 RAs have been of great interest since the burden from cardiovascular diseases (CVD) has been unbearably increasing in a diabetic population worldwide, despite strict glycemic control and advanced therapeutic techniques to treat CVD. Preclinical studies have already demonstrated the beneficial effects of GLP-1 on myocardium and vascular endothelium, and many clinical studies evaluating changes in surrogate markers of CVD have suggested potential benefits from the use of GLP-1 RAs. Data from numerous clinical trials primarily evaluating the antihyperglycemic effects of multiple GLP-1 RAs have also revealed that changes in most CVD risk markers reported as secondary outcomes have been in favor of GLP-1 RAs treatment. However, to date, there is only one randomized clinical trial of GLP-1 RAs (the ELIXA study) evaluating major cardiovascular events as their primary outcomes, and in this study, a neutral cardiovascular effect of lixisenatide was observed in high-risk diabetic subjects. Therefore, the results of ongoing CVD outcome trials with the use of GLP-1 RAs should be awaited to elucidate the translation of benefits previously seen in CVD risk marker studies into large clinical trials with primary cardiovascular outcomes.

Heart Failure Considerations of Antihyperglycemic Medications for Type 2 Diabetes

Prevalent and incident heart failure (HF) is increased in people with type 2 diabetes mellitus, with risk directly associated with the severity of hyperglycemia. Furthermore, in patients with type 2 diabetes mellitus, mortality is increased ≈10-fold in patients with versus without HF. Reducing HF with antihyperglycemic therapies, however, has been unsuccessful until recently. In fact, HF as an important outcome in patients with type 2 diabetes mellitus seems to be heterogeneously modulated by antihyperglycemic medications, as evidenced by results from cardiovascular outcome trials (CVOTs) and large observational cohort studies. Appropriately powered and executed CVOTs are necessary to truly evaluate cardiovascular safety and efficacy of new antihyperglycemic medications, as reflected by the guidance of the US Food and Drug Administration and other regulatory agencies since 2008. In light of the best available evidence at present, metformin and the sodium-glucose-co-transporter 2-inhibitor empagliflozin seem to be especially advantageous with regard to HF effects, with their use associated with reduced HF events and improved mortality. Acarbose, the dipeptidyl-peptidase 4-inhibitor sitagliptin, the glucagon-like peptide 1-receptor agonist lixisenatide based on presently available CVOT results comprise reasonable additional options, as significant harm in terms of HF has been excluded for those drugs. Additions to this list are anticipated pending results of ongoing CVOTs. Although no HF harm was seen in CVOTs for insulin or sulfonylureas, they should be used only with caution in patients with HF, given their established high risk for hypoglycemia and some uncertainties on their safety in patients with HF derived from epidemiological observations. Pioglitazone is contraindicated in patients with HF>New York Heart Association I, despite some benefits suggested by CVOT subanalyses.

Exenatide acutely increases heart rate in parallel with augmented sympathetic nervous system activation in healthy overweight males

AIM

Clinical use of glucagon-like peptide-1 receptor agonists (GLP-1RA) is consistently associated with heart rate (HR) acceleration in type 2 diabetes patients. We explored the mechanisms underlying this potential safety concern.

METHODS

Ten healthy overweight males (aged 20-27 years) were examined in an open label, crossover study. Automated oscillometric blood pressure measurements and finger photoplethysmography were performed throughout intravenous administration of placebo (saline 0.9%), exenatide (targeting therapeutic concentrations) and a combination of exenatide and the nitric oxide synthase inhibitor L-N(G) -monomethyl arginine (L-NMMA). Sympathetic nervous system (SNS) activity was measured by heart rate variability and rate-pressure product.

RESULTS

Exenatide increased HR by a mean maximum of 6.8 (95% CI 1.7, 11.9) beats min(-1) (P < 0.05), systolic blood pressure (SBP) by 9.8 (95% CI 3.5, 16.1) mmHg (P < 0.01) and markers of SNS activity (P < 0.05). No changes in total peripheral resistance were observed. Increases in HR, SBP and sympathetic activity were preserved during concomitant L-NMMA infusion.

CONCLUSIONS

Our data argue against exenatide-induced reflex tachycardia as a response to vasodilation and rather suggest the involvement of SNS activation in humans.