Effects of liraglutide on cardiovascular risk biomarkers in patients with type 2 diabetes and albuminuria: A sub-analysis of a randomized, placebo-controlled, double-blind, crossover trial

Comparative Analysis of the Anti-Inflammatory Effects of Liraglutide and Dulaglutide

Inflammation plays a pathophysiological role in atherosclerosis and its clinical consequences. In addition to glycemic control, glucagon-like peptide-1 receptor agonists (GLP-1RAs) are of wide concern for cardioprotective effects. The structure, half-life, homology, and clinical efficacy of GLP-1RAs exhibit remarkable disparity. Several studies have compared the disparities in anti-inflammatory effects between daily and weekly GLP-1RAs. This study aimed to compare the similarities and differences between liraglutide and dulaglutide in terms of inhibiting atherosclerotic inflammation and improving co-cultured endothelial cell function. The expression of inflammation markers was examined by immunofluorescence, Western blotting, and real-time PCR. The tube-forming ability of endothelial cells was tested on Matrigel. The results verify that 10/50/100 nmol/L liraglutide and 100 nmol/L dulaglutide markedly suppressed the expression of inflammatory factors in LPS-induced atherosclerosis after 24 and 72 hours, respectively. Moreover, they promoted the polarization of M1 macrophages toward the M2 phenotype and improved the function of co-cultured endothelial cells. Both liraglutide and dulaglutide ameliorate atherosclerosis development. The difference between the two resided in the extended intervention duration required to observe the effect of dulaglutide, and liraglutide demonstrated a superior dose-dependent manner. We provide a potential strategy to understand the dynamics of drug action and possible timing administration.

GLP-1 receptor agonists and atherosclerosis protection: the vascular endothelium takes center stage

Atherosclerotic cardiovascular disease is a chronic condition that often copresents with type 2 diabetes and obesity. Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are incretin mimetics endorsed by major professional societies for improving glycemic status and reducing atherosclerotic risk in people living with type 2 diabetes. Although the cardioprotective efficacy of GLP-1RAs and their relationship with traditional risk factors are well established, there is a paucity of publications that have summarized the potentially direct mechanisms through which GLP-1RAs mitigate atherosclerosis. This review aims to narrow this gap by providing comprehensive and in-depth mechanistic insight into the antiatherosclerotic properties of GLP-1RAs demonstrated across large outcome trials. Herein, we describe the landmark cardiovascular outcome trials that triggered widespread excitement around GLP-1RAs as a modern class of cardioprotective agents, followed by a summary of the origins of GLP-1RAs and their mechanisms of action. The effects of GLP-1RAs at each major pathophysiological milestone of atherosclerosis, as observed across clinical trials, animal models, and cell culture studies, are described in detail. Specifically, this review provides recent preclinical and clinical evidence that suggest GLP-1RAs preserve vessel health in part by preventing endothelial dysfunction, achieved primarily through the promotion of angiogenesis and inhibition of oxidative stress. These protective effects are in addition to the broad range of atherosclerotic processes GLP-1RAs target downstream of endothelial dysfunction, which include systemic inflammation, monocyte recruitment, proinflammatory macrophage and foam cell formation, vascular smooth muscle cell proliferation, and plaque development.

Liraglutide and not lifestyle intervention reduces soluble CD163 after comparable weight loss in obese participants with prediabetes or type 2 diabetes mellitus

BACKGROUND

The GLP-1 receptor agonist liraglutide is used to treat hyperglycemia in type 2 diabetes but is also known to induce weight loss, preserve the beta cell and reduce cardiovascular risk. The mechanisms underlying these effects are however still not completely known. Herein we explore the effect of liraglutide on markers of immune cell activity in a population of obese individuals with prediabetes or newly diagnosed type 2 diabetes mellitus.

METHOD

Plasma levels of the monocyte/macrophage markers, soluble (s)CD163 and sCD14, the neutrophil markers myeloperoxidase (MPO) and neutrophil gelatinase-associated lipocalin (NGAL),the T-cell markers sCD25 and T-cell immunoglobulin mucin domain-3 (sTIM-3) and the inflammatory marker TNF superfamily (TNFSF) member 14 (LIGHT/TNFSF14) were measured by enzyme-linked immunosorbent assays in obese individuals with prediabetes or diabetes diagnosed within the last 12 months, prior to and after comparable weight loss achieved with lifestyle changes (n = 20) or liraglutide treatment (n = 20), and in healthy subjects (n = 13).

RESULTS

At baseline, plasma levels of the macrophage marker sCD163, and the inflammatory marker LIGHT were higher in cases as compared to controls. Plasma levels of sCD14, NGAL, sTIM-3 and sCD25 did not differ at baseline between patients and controls. After weight reduction following lifestyle intervention or liraglutide treatment, sCD163 decreased significantly in the liraglutide group vs. lifestyle (between-group difference p = 0.023, adjusted for visceral adipose tissue and triglycerides basal values). MPO and LIGHT decreased significantly only in the liraglutide group (between group difference not significant). Plasma levels of MPO and in particular sCD163 correlated with markers of metabolic dysfunction and inflammation. After weight loss, only sCD163 showed a trend for decreased levels during OGTT, both in the whole cohort as in those of liraglutide vs lifestyle group.

CONCLUSION

Weight loss following treatment with liraglutide was associated with reduced circulating levels of sCD163 when compared to the same extent of weight loss after lifestyle changes. This might contribute to reduced cardiometabolic risk in individuals receiving treatment with liraglutide.

Safety and Efficacy of Liraglutide on Cardiovascular Outcomes in Patients With Diabetes Mellitus: A Meta-Analysis of Randomized Controlled Trials

Diabetes mellitus (DM) is a chronic metabolic disorder, with type 2 diabetes (T2DM) significantly impacting the cardiovascular (CV) system. Our comprehensive study on the cardiovascular effects of liraglutide, conducted concurrently with the formulation of diabetes treatment guidelines, aims to provide healthcare providers and patients with reassurance regarding the safety and effectiveness of liraglutide. From the beginning until August 20, 2023, we conducted searches in databases including PubMed, Web of Science, Embase, Cochrane Library, Scopus, and Google Scholar. These searches aimed to identify studies comparing liraglutide to control in terms of symptom resolution among patients with T2DM. For all relevant outcomes, we calculated risk ratios along with their corresponding 95% confidence intervals. Thirteen randomized controlled trials (RCTs) were included in this analysis. The results demonstrated a significant reduction in the risk of major adverse cardiovascular events (MACE), myocardial infarction, CV mortality, and all-cause mortality. No significant difference was found between the liraglutide and control groups for the outcome of stroke. However, sensitivity analysis revealed a significant reduction in the risk of stroke among patients taking liraglutide. Our comprehensive meta-analysis strongly supports the use of liraglutide for managing cardiovascular disease (CVD) due to its established safety and effectiveness. Further RCTs and meta-analyses are needed to more thoroughly evaluate liraglutide's therapeutic potential, with the aim of enhancing the quality of life for those with CVD.

The anti-inflammatory and immunological properties of GLP-1 Receptor Agonists

In the last few years, a great interest has emerged in investigating the pleiotropic effects of Glucagon Like Peptide-1 Receptor Agonists (GLP-1RAs). While GLP-1RAs ability to lower plasma glucose and to induce weight loss has allowed them to be approved for the treatment of diabetes and obesity, consistent evidences from in vitro studies and preclinical models suggested that GLP-1RAs have anti-inflammatory properties and that may modulate the immune-system. Notably, such anti-inflammatory effects target different pathways in different tissues, underling the broad spectrum of GLP-1RAs actions. This review examines some of the currently proposed molecular mechanisms of GLP-1RAs actions and explores their potential benefits in reducing inflammatory responses, which may well suggest a future therapeutic use of GLP-1RAs in new indications.

Semaglutide treatment attenuates vessel remodelling in ApoE-/- mice following vascular injury and blood flow perturbation

Background and aims

Randomized clinical studies have shown a reduction in cardiovascular outcomes with glucagon-like peptide 1 receptor agonist (GLP-1RA) treatment with the hypothesized mechanisms being an underlying effect on atherosclerosis. Here, we aimed to assess the pharmacological effects of semaglutide in an atheroprone murine model that recapitulates central mechanisms related to vascular smooth muscle cell (VSMC) phenotypic switching and endothelial dysfunction known to operate within the atherosclerotic plaque.

Methods

In study A, we employed an electrical current to the carotid artery in ApoE-/- mice to induce severe VSMC injury and death, after which the arteries were allowed to heal for 4 weeks. In study B, a constrictive cuff was added for 6 h at the site of the healed segment to induce a disturbance in blood flow.

Results

Compared to vehicle, semaglutide treatment reduced the intimal and medial area by ∼66% (p = 0.007) and ∼11% (p = 0.0002), respectively. Following cuff placement, expression of the pro-inflammatory marker osteopontin and macrophage marker Mac-2 was reduced (p < 0.05) in the semaglutide-treated group compared to vehicle. GLP-1R were not expressed in murine carotid artery and human coronary vessels with and without atherosclerotic plaques, and semaglutide treatment did not affect proliferation of cultured primary human VSMCs.

Conclusions

Semaglutide treatment reduced vessel remodelling following electrical injury and blood flow perturbation in an atheroprone mouse model. This effect appears to be driven by anti-inflammatory and -proliferative mechanisms independent of GLP-1 receptor-mediated signalling in the resident vascular cells. This mechanism of action may be important for cardiovascular protection.

Proinflammatory biomarkers are associated with prediabetes in patients with schizophrenia

BACKGROUND

Treatment with antipsychotics is associated with an increased risk of type 2 diabetes mellitus (T2D), and increased levels of inflammatory biomarkers are present in patients with T2D. We previously demonstrated that the glucagon-like peptide-1 receptor agonist liraglutide significantly reduced glucometabolic disturbances and body weight in prediabetic, overweight/obese schizophrenia-spectrum disorder patients treated with clozapine or olanzapine. This study aims to assess the involvement of cytokines in the therapeutic effects of liraglutide.

METHODS

Serum concentrations of 10 cytokines (interferon-γ [IFN-γ], tumor necrosis factor-α, interleukin 1β [IL-1β], IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p70, and IL-13) from fasting prediabetic and normal glucose-tolerant (NGT) patients with schizophrenia-spectrum disorders were measured using multiplexed immunoassays. Prediabetic patients were randomized to 16 weeks of treatment with liraglutide or placebo, and cytokines were measured again at the end of the treatment.

RESULTS

IFN-γ (1.98 vs 1.17 pg/ml, P = .001), IL-4 (0.02 vs 0.01 pg/ml, P < .001), and IL-6 (0.73 vs 0.46 pg/ml, P < .001) were significantly higher in prediabetic (n = 77) vs NGT patients (n = 31). No significant changes in cytokine levels following treatment with liraglutide (n = 37) vs placebo (n = 40) were found.

CONCLUSION

Prediabetic vs NGT patients with schizophrenia treated with clozapine or olanzapine had increased serum levels of several proinflammatory cytokines, further substantiating the link between inflammation and T2D. Treatment with liraglutide did not affect the investigated cytokines. Further testing of these findings in larger numbers of individuals is needed.

Effect of a 3-Week Treatment with GLP-1 Receptor Agonists on Vasoactive Hormones in Euvolemic Participants

CONTEXT

Glucagon-like-peptide-1 receptor agonists (GLP-1 RAs) exert cardiovascular benefits by reducing plasma glucose, body weight, and blood pressure. The blood pressure-lowering effect may be mediated by angiotensin II (ANG II) suppression and consecutive natriuresis. However, the role of ANG II and other vasoactive hormones on GLP-1 RA treatment has not been clearly defined.

OBJECTIVE

This work aimed to investigate the effect of a 3-week treatment with the GLP-1 RA dulaglutide on vasoactive hormones, that is, renin, ANG II, aldosterone, mid-regional proatrial natriuretic peptide (MP-proANP), and natriuresis in euvolemic participants.

METHODS

Randomized, double-blinded, placebo-controlled, crossover trials were conducted at University Hospital Basel, Switzerland. A total of 54 euvolemic participants, including 20 healthy individuals and 34 patients with primary polydipsia, received a subcutaneous injection of dulaglutide (Trulicity) 1.5 mg and placebo (0.9% sodium chloride) once weekly over a 3-week treatment phase.

RESULTS

After a 3-week treatment phase, dulaglutide showed no effect on plasma renin, plasma ANG II, or plasma aldosterone levels in comparison to placebo. Natriuresis remained unchanged or decreased on dulaglutide depending on the measured parameter. Dulaglutide significantly decreased plasma MR-proANP levels (treatment effect: 10.60 pmol/L; 95% CI, -14.70 to -7.90; P < .001) and systolic blood pressure (median: 3 mm Hg; 95% CI, -5 to 0; P = .036), whereas heart rate increased (median: 5 bpm; 95% CI, 3-11; P < .001).

CONCLUSION

In euvolemic participants, a 3-week treatment of dulaglutide reduced systolic blood pressure independently of plasma renin, ANG II, or aldosterone levels and urinary sodium excretion. The reduction in MR-proANP might be secondary to reduced arterial pulse pressure.

Skeletal Muscle Microvascular Dysfunction in Obesity-Related Insulin Resistance: Pathophysiological Mechanisms and Therapeutic Perspectives

Obesity is a worrisomely escalating public health problem globally and one of the leading causes of morbidity and mortality from noncommunicable disease. The epidemiological link between obesity and a broad spectrum of cardiometabolic disorders has been well documented; however, the underlying pathophysiological mechanisms are only partially understood, and effective treatment options remain scarce. Given its critical role in glucose metabolism, skeletal muscle has increasingly become a focus of attention in understanding the mechanisms of impaired insulin function in obesity and the associated metabolic sequelae. We examined the current evidence on the relationship between microvascular dysfunction and insulin resistance in obesity. A growing body of evidence suggest an intimate and reciprocal relationship between skeletal muscle microvascular and glucometabolic physiology. The obesity phenotype is characterized by structural and functional changes in the skeletal muscle microcirculation which contribute to insulin dysfunction and disturbed glucose homeostasis. Several interconnected etiologic molecular mechanisms have been suggested, including endothelial dysfunction by several factors, extracellular matrix remodelling, and induction of oxidative stress and the immunoinflammatory phenotype. We further correlated currently available pharmacological agents that have deductive therapeutic relevance to the explored pathophysiological mechanisms, highlighting a potential clinical perspective in obesity treatment.

Effects of GLP-1 receptor agonists on myokine levels and pro-inflammatory cytokines in patients with type 2 diabetes mellitus

BACKGROUND AND AIMS

To evaluate the change in circulating serum irisin and interleukin-6 (IL-6), in patients with type 2 diabetes mellitus (T2DM) after 6 and 12 months of GLP-1 treatment.

METHODS AND RESULTS

Eighty-five patients with T2DM inadequately controlled with insulin or other hypoglycaemic drugs were added to dulaglutide (N° = 44) and liraglutide (N° = 41) treatment. After 6 months of GLP-1 analogues a significant decrease in BMI (p < 0.001), waist circumference (WC) (p < 0.001), fasting blood glucose (p < 0.001), HbA1c (p < 0.001), total cholesterol (p < 0.001), LDL-cholesterol (p = 0.003), triglycerides (p = 0.017), IL-6 (p = 0.045) and a significant increase in serum irisin (p < 0.001) were observed compared to baseline. After 12 months of treatment no significant differences were found compared to the levels at 6 months. The change in irisin from baseline (Δ_irisin) was significantly related to the changes in total-cholesterol (Δ_total-cholesterol) (r = -0.293; p = 0.020), while the change in IL-6 (Δ_IL-6) was significantly related to the changes in WC (Δ_WC) (r = 0.347; p = 0.006).

CONCLUSIONS

Additive treatment with GLP1-analogues results in an increase in serum circulating irisin levels and a decrease in IL-6. The post-treatment change in irisin was correlated with a decrease in total cholesterol, while the change in IL-6 was correlated with a decrease in WC.

Effect of liraglutide on expression of inflammatory genes in type 2 diabetes

Anti-inflammatory effects of glucagon-like peptide 1 receptor agonist (GLP-1 RA) treatment in T2D may contribute to the cardiovascular benefits observed with GLP-1 RAs in outcome studies. We investigated if the GLP-1 RA liraglutide exerts anti-inflammatory effects through modulation of inflammatory gene expression in peripheral blood mononuclear cells (PBMCs). From 54 participants of a double-blinded trial where individuals with type 2 diabetes (T2D) were randomized to liraglutide (1.8 mg/day) or placebo for 26 weeks, a sub-study was performed in which PBMCs were extracted from fresh blood at study start and at end-of-treatment. The expression of selected inflammatory genes in PBMCs were measured by quantitative real-time polymerase chain reaction (PCR). Moreover, the expression of the GLP-1 receptor (GLP1R) was examined in a subset (n = 40) of the PBMC samples. The human monocytic cell line THP-1 was used for in vitro GLP-1 exposure experiments. The expression of tumor necrosis factor-α (TNFA) (p = 0.004) and interleukin-1β (IL1B) was downregulated (p = 0.046) in the liraglutide-treated group (n = 31), and unchanged in the placebo group (n = 21, p ≥ 0.11), with no significant differences between the two groups (p ≥ 0.67). The expression of interferon-γ (IFNG) and cluster of differentiation 163 (CD163) were upregulated in both groups (p ≤ 0.006) with no differences between groups (p ≥ 0.47). C–C Motif Chemokine Ligand 5 (CCL5) was upregulated in the liraglutide-treated group (p = 0.002) and unchanged in the placebo group (p = 0.14), with no significant difference between groups (p = 0.36). Intercellular adhesion molecule 1 (ICAM1) was unchanged in both groups (p ≥ 0.43). GLP1R expression in the PBMCs was undetectable. In vitro experiments showed no effect of GLP-1 treatment on inflammatory gene expression in THP-1 cells. GLP1R expression in THP-1 cells was not detectable. In summary, we observed a discrete modulatory effect of liraglutide on the expression of inflammatory genes in PBMCs. The lack of evidence for GLP1R expression in PBMCs and THP-1 cells suggests that possible effects of liraglutide on the PBMCs’ gene expression are most likely indirect. Further investigations are needed to establish the anti-inflammatory potential of GLP-1 RAs.

Effect of Liraglutide on Vascular Inflammation Evaluated by [64Cu]DOTATATE

Quantification of vascular inflammation before and after treatment with glucagon-like peptide-1 receptor agonists (GLP-1 RAs) may help reveal mechanistic pathways underlying the cardiovascular benefits of these drugs. We assessed change in vascular inflammation in the carotid arteries over 26 weeks by copper-64-labeled [1,4,7,10-tetraazacyclododecane-N,N′,N″,N‴-tetraacetic acid]-D-Phe1, Tyr3-octreotate ([⁶⁴Cu]DOTATATE) PET in 30 participants included in a substudy of a double-blind trial where persons with type 2 diabetes (T2D) were randomized to liraglutide (n = 15) or placebo (n = 15) for 26 weeks. Mean age (SD) was 66.4 (7.2) years, HbA_1c 56.4 (9.2) mmol/mol and BMI 28.9 (4.6) kg/m². Weight and HbA_1c were significantly reduced by liraglutide vs. placebo (p ≤ 0.01). The [⁶⁴Cu]DOTATATE uptake (mean standardized uptake values) was significantly reduced in the liraglutide-treated group (−0.11 [95% confidence interval −0.19 to −0.03], p = 0.01) and not changed significantly in the placebo group (−0.07 [−0.14 to 0.01], p = 0.08). The mean difference between groups did not reach significance (−0.04 [−0.15 to 0.07], p = 0.44). In conclusion, [⁶⁴Cu]DOTATATE uptake was reduced in persons with T2D treated with liraglutide. However, the reduction compared to placebo did not reach statistical significance, perhaps due to limited power. A reduction in vascular inflammation with liraglutide could help explain the cardiovascular protection observed with GLP-1 RAs in outcome studies but warrants further and larger studies.

Glucagon-like peptide-1 receptor agonists improve biomarkers of inflammation and oxidative stress: A systematic review and meta-analysis of randomised controlled trials

AIM

To conduct a meta-analysis and systematic review to examine the effects of glucagon-like peptide-1 receptor agonists (GLP-1RAs) on clinical biomarkers of inflammation and oxidative stress in patients with type 2 diabetes.

METHODS

Medline, Embase and the Cochrane Library were searched for randomised controlled trials (RCTs) that examined changes with GLP-1RAs in a priori selected biomarkers of inflammation: C-reactive protein (CRP), adiponectin, tumour necrosis factor-alpha (TNFα), plasminogen activator inhibitor-1, interleukin-6, leptin; and of oxidative stress: malondialdehyde (MDA); 8-iso-prostaglandin F2α; and 8-hydroxy-2'-deoxyguanosine (8-OHdG).

RESULTS

We included 40 eligible RCTs (n = 6749) with a median follow-up of 6 months, a mean participant age of 53.1 years, 56.3% females, glycated haemoglobin (HbA1c) 55.6 mmol/mol, body mass index 28.8 kg/m² and diabetes duration 7.46 years. Analysis of GLP-1RAs versus standard diabetes therapies or placebo revealed significant reductions in CRP, TNFα and MDA, and significant increases in adiponectin for (mean difference -0.54 mg/L [-0.75, -0.34]; standard mean difference [SMD] -0.39 [-0.62, -0.15]; SMD -0.84 [-1.61, -0.06] and SMD 0.30 [0.12, 0.49], respectively [95% confidence intervals]). Systolic blood pressure decreased significantly and was significantly and strongly correlated with a reduction in CRP. Homeostatic model assessment of insulin resistance was also significantly correlated with a reduction in CRP, but HbA1c was not.

CONCLUSIONS

There is strong evidence supporting clinically relevant anti-inflammatory and antioxidant effects of GLP-1RAs. This may be used to guide future targeted clinical use of GLP-1RAs and the development of medications seeking to target the cardioprotective properties of GLP-1RAs.

Effect of Liraglutide on Arterial Inflammation Assessed as [18F]FDG Uptake in Patients With Type 2 Diabetes: A Randomized, Double-Blind, Placebo-Controlled Trial

BACKGROUND

The mechanism behind the cardiovascular protection observed with human GLP-1 RA (glucagon-like peptide-1 receptor agonists) in type 2 diabetes is unknown. We hypothesized that treatment with the GLP-1 RA liraglutide had a positive effect on vascular inflammation.

METHODS

LIRAFLAME (Effect of liraglutide on vascular inflammation in type-2 diabetes: A randomized, placebocontrolled, double-blind, parallel clinical PET/CT trial) was a double-blind, randomized controlled trial performed at a single university hospital clinic in Denmark. Patients with type 2 diabetes were via computer-generated randomization list assigned (1:1) liraglutide up to 1.8 mg or placebo once daily for 26 weeks. The primary end point was change in vascular inflammation over 26 weeks assessed by [¹⁸F]-fluorodeoxyglucose positron emission tomography/computed tomography. Analyses were based on intention-to-treat. Key secondary outcomes included change in other indices of atherosclerosis.

RESULTS

Between October 26, 2017, and August 16, 2019, 147 patients were screened and 102 were randomly assigned to liraglutide (n=51) or placebo (n=51) and 99 (97%) completed the trial. Change in the [¹⁸F]-fluorodeoxyglucose positron emission tomography measure of vascular inflammation (active-segment target-to-background ratio) did not differ between treatment groups: change from baseline to 26 weeks was -0.04 (95% CI, -0.17 to 0.08) in the liraglutide group compared with -0.09 (-0.19 to 0.01) in the placebo group (mean difference, 0.05 [95% CI, -0.11 to 0.21], P=0.53). Secondary analyses restricted to [¹⁸F]-fluorodeoxyglucose positron emission tomography of the carotid arteries as well as other indices of atherosclerosis confirmed the primary result. We performed an explorative analysis of interaction between treatment group and history of cardiovascular disease (P=0.052).

CONCLUSIONS

In this low to moderate risk population with type 2 diabetes, liraglutide did not change vascular inflammation assessed as [¹⁸F]-fluorodeoxyglucose uptake compared with placebo. An explorative analysis indicated a possible effect in persons with history of cardiovascular disease, in line with current guidelines where liraglutide is recommended to patients with history of cardiovascular disease. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03449654.

Current and future therapies for type 1 diabetes

In type 1 diabetes, insulin remains the mature therapeutic cornerstone; yet, the increasing number of individuals developing type 1 diabetes (predominantly children and adolescents) still face severe complications. Fortunately, our understanding of type 1 diabetes is continuously being refined, allowing for refocused development of novel prevention and management strategies. Hitherto, attempts based on immune suppression and modulation have been only partly successful in preventing the key pathophysiological feature in type 1 diabetes: the immune-mediated derangement or destruction of beta cells in the pancreatic islets of Langerhans, leading to low or absent insulin secretion and chronic hyperglycaemia. Evidence now warrants a focus on the beta cell itself and how to avoid its dysfunction, which is putatively caused by cytokine-driven inflammation and other stress factors, leading to low insulin-secretory capacity, autoantigen presentation and immune-mediated destruction. Correspondingly, beta cell rescue strategies are being pursued, which include antigen vaccination using, for example, oral insulin or peptides, as well as agents with suggested benefits on beta cell stress, such as verapamil and glucagon-like peptide-1 receptor agonists. Whilst autoimmune-focused prevention approaches are central in type 1 diabetes and will be a requirement in the advent of stem cell-based replacement therapies, managing the primarily cardiometabolic complications of established type 1 diabetes is equally essential. In this review, we outline selected recent and suggested future attempts to address the evolving profile of the person with type 1 diabetes.

Liraglutide Increases the Catabolism of Apolipoprotein B100-Containing Lipoproteins in Patients With Type 2 Diabetes and Reduces Proprotein Convertase Subtilisin/Kexin Type 9 Expression

OBJECTIVE

Dyslipidemia observed in type 2 diabetes (T2D) is atherogenic. Important features of diabetic dyslipidemia are increased levels of triglyceride-rich lipoproteins and small dense LDL particles, which all have apolipoprotein B100 (apoB100) as a major apolipoprotein. This prompted us to study the effect of the GLP-1 agonist liraglutide on the metabolism of apoB100-containing lipoproteins.

RESEARCH DESIGN AND METHODS

We performed an in vivo kinetic study with stable isotopes (L-[1-¹³C]leucine) in 10 patients with T2D before and after 6 months of treatment with liraglutide (1.2 mg/day). We also evaluated in mice the effect of liraglutide on the expression of genes involved in apoB100-containing lipoprotein clearance.

RESULTS

In patients with T2D, liraglutide treatment significantly reduced plasma apoB100 (0.93 ± 0.13 vs. 1.09 ± 0.11 g/L, P = 0.011) and fasting triglycerides (1.76 ± 0.37 vs. 2.48 ± 0.69 mmol/L, P = 0.005). The kinetic study showed a significant increase in indirect catabolism of VLDL₁-apoB100 (4.11 ± 1.91 vs. 2.96 ± 1.61 pools/day, P = 0.005), VLDL₂-apoB100 (5.17 ± 2.53 vs. 2.84 ± 1.65 pools/day, P = 0.008), and IDL-apoB100 (5.27 ± 2.77 vs. 3.74 ± 1.85 pools/day, P = 0.017) and in catabolism of LDL-apoB100 (0.72 ± 0.22 vs. 0.56 ± 0.22 pools/day, P = 0.005). In mice, liraglutide increased lipoprotein lipase (LPL) gene expression and reduced proprotein convertase subtilisin/kexin type 9 (PCSK9), retinol-binding protein 4 (RBP4), and tumor necrosis factor-α (TNF-α) gene expression in adipose tissue and decreased PCSK9 mRNA and increased LDL receptor protein expression in liver. In vitro, liraglutide directly reduced the expression of PCSK9 in the liver.

CONCLUSIONS

Treatment with liraglutide induces a significant acceleration of the catabolism of triglyceride-rich lipoproteins (VLDL₁, VLDL₂, IDL) and LDL. Liraglutide modifies the expression of genes involved in apoB100-containing lipoprotein catabolism. These positive effects on lipoprotein metabolism may reduce cardiovascular risk in T2D.

Dulaglutide exerts beneficial anti atherosclerotic effects in ApoE knockout mice with diabetes: the earlier, the better

There has been no report about the mechanism for anti-atherosclerotic effects of dulaglutide (Dula) and/or about the difference of its effectiveness between in an early and a late phase of diabetes. To address such questions, streptozotocin (STZ) was intraperitoneally injected to ApoE knockout mice at 8 weeks of age. Either Dula or vehicle was administered to STZ-induced diabetic ApoE knockout mice from 10 to 18 weeks of age as an early intervention group and from 18 to 26 weeks as a late intervention group. Next, non-diabetic ApoE knockout mice without STZ injection were subcutaneously injected with either Dula or vehicle. In an early intervention group, atherosclerotic lesion in aortic arch and Mac-2 and CD68-positive areas in aortic root were significantly smaller in Dula group. In abdominal aorta, expression levels of some villain factors were lower in Dula group. In a late intervention group, there were no immunohistological differences in aortic root and expression levels of various factors between two groups. Furthermore, even in non-diabetic ApoE knockout mice, expression levels of inflammatory and macrophage markers were reduced by treatment with Dula. Taken together, Dula exerts more beneficial anti-atherosclerotic effects in an early phase of diabetes rather than in a late phase.

Effects of Liraglutide on Left Ventricular Function: A Meta-Analysis of Randomized, Placebo-Controlled Trials

BACKGROUND

The effects of liraglutide treatment on the left ventricular systolic and diastolic function remain unclear.

METHODS

This meta-analysis was conducted according to the preferred reporting items for systematic reviews and meta-analysis (PRISMA) statement. All relevant randomized, placebo-controlled trials (RCTs) were identified by searching PubMed, EMBASE, Cochrane Library, and ISI Web of Science from the establishment to January 2021 without language limitations. The weighted mean difference (WMD) with 95% confidence intervals (CIs) was calculated.

RESULTS

Ten placebo-controlled RCTs involving a total of 732 cases were included in the meta-analysis. Compared with the placebo group, liraglutide therapy showed no beneficial effect on the left ventricular ejection fraction (LVEF) at the end of the study (WMD: 2.120, 95% CI: -0.688 to 4.929, P=0.139) and ΔLVEF during the trial period (WMD: -0.651, 95% CI: -1.649 to 0.348, P=0.202). Similarly, no statistical differences were noted in diastolic function parameters between the two groups, including the value early diastolic filling velocity (E)/the mitral annular early diastolic velocity (e') (WMD: -0.763, 95% CI: -2.157 to 0.630, P=0.283), Δe' (WMD: -0.069, 95% CI: -0.481 to 0.343, P=0.742), and ΔE/e' (WMD: -0.683, 95% CI: -1.663 to 0.298, P=0.172).

CONCLUSIONS

Liraglutide treatment did not improve the left ventricular systolic and diastolic function. Given the study's limitations, further investigation may be warranted.

Management of post-transplant diabetes: immunosuppression, early prevention, and novel antidiabetics

Post‐transplant diabetes mellitus (PTDM) shows a relationship with risk factors including obesity and tacrolimus‐based immunosuppression, which decreases pancreatic insulin secretion. Several of the sodium–glucose‐linked transporter 2 inhibitors (SGLT2is) and glucagon‐like peptide 1 receptor agonists (GLP1‐RAs) dramatically improve outcomes of individuals with type 2 diabetes with and without chronic kidney disease, which is, as heart failure and atherosclerotic cardiovascular disease, differentially affected by both drug classes (presumably). Here, we discuss SGLT2is and GLP1‐RAs in context with other PTDM management strategies, including modification of immunosuppression, active lifestyle intervention, and early postoperative insulin administration. We also review recent studies with SGLT2is in PTDM, reporting their safety and antihyperglycemic efficacy, which is moderate to low, depending on kidney function. Finally, we reference retrospective case reports with GLP1‐RAs that have not brought forth major concerns, likely indicating that GLP1‐RAs are ideal for PTDM patients suffering from obesity. Although our article encompasses PTDM after solid organ transplantation in general, data from kidney transplant recipients constitute the largest proportion. The PTDM research community still requires data that treating and preventing PTDM will improve clinical conditions beyond hyperglycemia. We therefore suggest that it is time to collaborate, in testing novel antidiabetics among patients of all transplant disciplines.

The impact of the glucagon-like peptide-1 receptor agonist liraglutide on natriuretic peptides in heart failure patients with reduced ejection fraction with and without type 2 diabetes

AIM

To assess the effect of liraglutide, a glucagon-like peptide-1 receptor agonist, on urinary sodium excretion as well as on circulating adrenomedullin and copeptin levels in patients with type 2 diabetes (T2D).

MATERIALS AND METHODS

In the LIVE study, patients (n = 241) with left ventricular ejection fraction ≤45% were randomized to liraglutide 1.8 mg daily or placebo for 24 weeks, and 30% had a concomitant diagnosis of T2D. Plasma levels of N-terminal brain-natriuretic-peptide (NT-proBNP) (a predefined secondary endpoint), midregional pro-atrial-natriuretic-peptide (MR-proANP), midregional pro-adrenomedullin (MR-proADM) and copeptin were measured at baseline and after 24 weeks in this substudy. The potential effect modification of T2D was assessed.

RESULTS

In the eligible subgroup of 231 patients with available biomarkers (115 randomized to liraglutide and 116 to placebo), MR-proANP decreased by 12% (P = .002) and NT-proBNP by 9% (P = .009) during liraglutide treatment compared with placebo at week 24. Interaction with T2D for the treatment effect of change in MR-proANP and NT-proBNP levels was P = .003 and P = .03, respectively. Consequently, in patients with T2D, liraglutide decreased MR-proANP by 27% (P < .001) and NT-proBNP by 25% (P = .02) compared with placebo, whereas no change was observed in patients without T2D. There was no effect of liraglutide on MR-proADM (P = .10) or copeptin (P = .52).

CONCLUSION

Liraglutide decreased the A- and B-type natriuretic peptides significantly in patients with heart failure with reduced ejection fraction (HFrEF) and concomitant T2D, suggesting a beneficial mechanism of liraglutide in T2D patients with HFrEF.

SGLT2 Inhibitor and GLP-1 Receptor Agonist Combination Therapy Substantially Improved the Renal Function in a Patient with Type 2 Diabetes: Implications for Additive Renoprotective Effects of the Two Drug Classes

A 72-year-old man had type 2 diabetes (T2D) that had been diagnosed at 54 years old. Macroalbuminuria was first detected at age 64. While his HbA1c had been kept below 7%, his estimated glomerular filtration rate (eGFR) was declining rapidly. At 70 years old, his eGFR dropped below 50 mL/min/1.73 m². A renal biopsy revealed diabetic nephropathy. Sodium glucose transporter 2 inhibitors (SGLT2i)/glucagon-like peptide-1 receptor agonists (GLP-1RA) combination therapy substantially improved his eGFR and urinary albumin level, and the renoprotective effect persisted for the two-year study period. These findings suggest that SGLT2i and GLP-1RA can additively improve the renal function in patients with T2D.

Soluble Urokinase Plasminogen Activator Receptor (suPAR) Concentrations Are Elevated in Patients with Neuroendocrine Malignancies

Neuroendocrine neoplasia (NEN) comprises heterogeneous tumors that are challenging to diagnose and, especially in cases of poorly differentiated (G3) NEN, are associated with very limited survival. Novel biomarkers allowing an early diagnosis as well as an optimal selection of suitable treatment options are urgently needed to improve the outcome of these patients. Recently, alterations of soluble urokinase-type plasminogen activator receptor (suPAR) serum levels were described in various types of cancers. However, the role of circulating suPAR as a biomarker in patients with NEN is unknown. In this study, we measured suPAR serum levels in a large and well-characterized cohort of 187 patients with NEN (neuroendocrine carcinomas (NEC) n = 30; neuroendocrine tumors (NET), n = 157) as well as 44 healthy controls. suPAR concentrations were significantly elevated in patients compared to controls. However, suPAR concentrations were independent of tumor-related factors such as the proliferation activity according to Ki-67, tumor grading, TNM (TNM classification of malignant tumors) stage, somatostatin receptor expression or clinical features such as functional or nonfunctional disease and the presence of tumor relapse. Interestingly, suPAR concentrations in NET patients were similar when compared to those measured in NEC patients. In contrast to previous results from other malignancies, in our analysis suPAR levels were not a significant predictor of overall survival. In conclusion, our data suggests that suPAR serum concentrations are elevated in NEN patients but do not allow prediction of outcome.

Heart Failure With Preserved Ejection Fraction and Diabetes: JACC State-of-the-Art Review

Heart failure with preserved ejection fraction (HFpEF) is now the most common form of HF, affecting over 3 million adults in the United States alone. HFpEF is a heterogenous syndrome. One important phenotype may be related to comorbid conditions, including diabetes mellitus (DM). DM has a prevalence of approximately 45% in HFpEF, but characteristics and outcomes of this population are poorly understood. In this review, the authors summarize data from several clinical trials of HFpEF therapeutics and provide original data from a large cohort using the Get With The Guidelines-HF registry, which together suggest that DM is associated with increased morbidity and long-term mortality in HFpEF. The authors then discuss several common pathological mechanisms in HFpEF and DM, including sodium retention, metabolic derangements, impaired skeletal muscle function, and potential therapeutic targets. As the understanding of comorbid HFpEF and DM improves, it is hoped clinicians will be better equipped to offer effective, patient-centered treatments.

Cardiovascular outcomes of liraglutide in patients with type 2 diabetes: A systematic review and meta-analysis

BACKGROUND

Liraglutide is a novel, long-acting glucagon-like peptide-1 (GLP-1) analogue used to treat type 2 diabetes mellitus. However, the cardiovascular safety and benefits of liraglutide treatment on type 2 diabetes patients remain in debate. In this study, we aimed to examine the overall cardiovascular outcomes of liraglutide in patients with type 2 diabetes.

METHODS

In this systematic review and meta-analysis, we searched the PubMed, Embase, and Web of Knowledge databases up to September 1st, 2017 for randomized trials in which type 2 diabetes patients were assigned to liraglutide and placebo or other comparators groups.

RESULTS

Eight studies fulfilled the eligibility criteria for inclusion and 14,608 patients were analyzed in this systematic review and meta-analysis. We found patients in the liraglutide group had a lower risk of major cardiovascular events (MACE) (RR = 0.89, 95% CI: 0.82-0.96, P = .002), acute myocardial infarction (AMI) (RR = 0.85, 95% CI: 0.74-0.99, P = .036), all-cause death (RR = 0.84, 95% CI: 0.74-0.96, P = .009), and cardiovascular death (RR = 0.77, 95% CI: 0.65-0.91, P = .002) than all comparator groups. However, liraglutide treatment did not decrease incidence of stroke (RR = 0.86, 95% CI: 0.70-1.04, P = .124). But among the MACE subgroups analysis, a significant reduction of MACE with liraglutide was only observed in placebo-controlled trials (RR = 0.89, 95% CI: 0.83-0.96, P = .004) but not in studies concerning other comparators (RR = 0.58, 95% CI: 0.29-1.16, P = .122).

CONCLUSIONS

In conclusion, our results suggest that liraglutide treatment decreases the risk of MACE, AMI, all-cause death and cardiovascular death among patients with type 2 diabetes.

Effect of Once-Weekly Exenatide in Patients With Type 2 Diabetes Mellitus With and Without Heart Failure and Heart Failure-Related Outcomes: Insights From the EXSCEL Trial

BACKGROUND

Once-weekly exenatide (EQW) had a neutral effect on hospitalization for heart failure (HHF) in the EXSCEL study (Exenatide Study of Cardiovascular Event Lowering), with no differential treatment effect on major adverse cardiac events by baseline heart failure (HF) status. EQW's effects on secondary end points based on HHF status have not been reported. The objective was to explore the effects of EQW on secondary end points in patients with and without baseline HF and test the effects of EQW on recurrent HHF events.

METHODS

The prespecified analysis of the randomized controlled EXSCEL trial, which enrolled patients with type 2 diabetes mellitus with and without additional cardiovascular disease, analyzed EQW effects on all-cause death, each major adverse cardiac event component, first HHF, and repeat HHF, by baseline HF status (regardless of ejection fraction). A subgroup analysis of the population stratified by preserved or reduced baseline ejection fraction was performed.

RESULTS

Of 14 752 EXSCEL participants, 2389 (16.2%) had HF at baseline. Compared with those without HF at baseline, patients with preexisting HF were older, and more likely to be male and white, with a higher burden of other cardiovascular diseases. Overall, those assigned to EQW had a lower incidence of all-cause death (hazard ratio [HR], 0.86 [95% CI, 0.77-0.97]) and the composite outcome of all-cause death or HHF (HR, 0.89 [95% CI, 0.80-0.99]). When stratified by presence or absence of baseline HF, there was no observed reduction in all-cause death with EQW with baseline HF (HR, 1.05 [95% CI, 0.85-1.29]), while the risk of mortality was reduced with EQW in the no-HF group (HR, 0.79 [95% CI, 0.68-0.92]) with an interaction P value of 0.031. The reduction in all-cause death or HHF seen with EQW in patients without baseline HF (HR, 0.81 [95% CI, 0.71-0.93]) was not seen in patients with baseline HF (HR, 1.07 [95% CI, 0.89-1.29]; interaction P=0.015). First, plus recurrent, HHF was reduced in the exenatide group versus placebo (HR, 0.82 [95% CI, 0.68-0.99]; P=0.038).

CONCLUSIONS

In EXSCEL, the use of EQW in patients with or without HF was well tolerated, but benefits of EQW on reduction in all-cause death and first hospitalization for HF were attenuated in patients with baseline HF.

CLINICAL TRIAL REGISTRATION

https://www.clinicaltrials.gov. Unique identifier: NCT01144338.

The future of new drugs for diabetes management

The future of the newer classes of glucose-lowering drugs, namely dipeptidyl peptidase-4 (DPP-4) inhibitors, glucagon-like peptide-1 receptor agonists (GLP-1RAs) and sodium/glucose co-transporter-2 (SGLT-2) inhibitors, is being redefined by the large prospective cardiovascular outcome trials (CVOTs). These trials have more than confirmed cardiovascular (CV) safety: indeed, various cardio-renal parameters have improved during some of the trials with GLP-1RAs and SGLT-2 inhibitors in type 2 diabetes. Benefits have included reductions in major adverse cardiovascular events such as fatal and non-fatal myocardial infarction and stroke, decreased hospitalization for heart failure, a slower decline in glomerular filtration rate and reduced onset and progression of albuminuria. In consequence, the CVOTs have raised expectations that newer glucose-lowering agents should offer advantages that extend beyond glycaemic control and weight management to address complications and comorbidities of type 2 diabetes, particularly cardio-renal diseases. Although large prospective outcome trials incur a high cost which may prompt reconsideration of their design, these trials are generating evidence to enable more exacting and more effective management of type 2 diabetes and its accompanying cardio-renal diseases.

Liraglutide treatment reduced interleukin-6 in adults with type 1 diabetes but did not improve established autonomic or polyneuropathy

AIMS

Type 1 diabetes can be complicated with neuropathy that involves immune-mediated and inflammatory pathways. Glucagon-like peptide-1 receptor agonists such as liraglutide, have shown anti-inflammatory properties, and thus we hypothesized that long-term treatment with liraglutide induced diminished inflammation and thus improved neuronal function.

METHODS

The study was a randomized, double-blinded, placebo-controlled trial of adults with type 1 diabetes and confirmed symmetrical polyneuropathy. They were randomly assigned (1:1) to receive either liraglutide or placebo. Titration was 6 weeks to 1.2-1.8 mg/d, continuing for 26 weeks. The primary endpoint was change in latency of early brain evoked potentials. Secondary endpoints were changes in proinflammatory cytokines, cortical evoked potential, autonomic function and peripheral neurophysiological testing.

RESULTS

Thirty-nine patients completed the study, of whom 19 received liraglutide. In comparison to placebo, liraglutide reduced interleukin-6 (-22.6%; 95% confidence interval [CI]: -38.1, -3.2; P = .025) with concomitant numerical reductions in other proinflammatory cytokines. However neuronal function was unaltered at the central, autonomic or peripheral level. Treatment was associated with -3.38 kg (95% CI: -5.29, -1.48; P < .001] weight loss and a decrease in urine albumin/creatinine ratio (-40.2%; 95% CI: -60.6, -9.5; P = .02).

CONCLUSION

Hitherto, diabetic neuropathy has no cure. Speculations can be raised whether mechanism targeted treatment, e.g. lowering the systemic level of proinflammatory cytokines may lead to prevention or treatment of the neuroinflammatory component in early stages of diabetic neuropathy. If ever successful, this would serve as an example of how fundamental mechanistic principles are translated into clinical practice similar to those applied in the cardiovascular and nephrological clinic.

Liraglutide in combination with metformin may improve the atherogenic lipid profile and decrease C-reactive protein level in statin treated obese patients with coronary artery disease and newly diagnosed type 2 diabetes: A randomized trial

BACKGROUND AND AIMS

Atherosclerosis in obesity and type 2 diabetes (T2DM) is associated with low-grade inflammation (LGI) and dyslipidemia, where especially small, dense lipoprotein particles are atherogenic. The glucagon-like peptide-1 receptor agonist, liraglutide, reduces cardiovascular events by poorly understood mechanisms. We investigated the effect of liraglutide combined with metformin on LGI and lipoprotein density profiles in patients with stable coronary artery disease (CAD) and newly diagnosed T2DM.

METHODS

We conducted a randomized, double-blind, placebo-controlled, cross-over trial over a 12 + 12-week period, with ≥2-week wash-out.

INTERVENTION

liraglutide/metformin vs. placebo/metformin. Lipoproteins were separated by continuous density gradient ultracentrifugation, and LDL divided into five subfractions between 226 and 270 Å, considering particle size ≤255 Å as the atherogenic pattern. Plasma C-reactive protein and tumor necrosis factor-α were assessed by the enzyme-linked immunosorbent-assay.

RESULTS

28 out of 41 randomized patients completed all visits. Intention-to-treat analysis was performed but one patient had statin dosage and was excluded from the analysis. 95% of the patients were on statin therapy. Overall, liraglutide did not affect lipid subfractions or markers of LGI compared to placebo. The combination of liraglutide and metformin reduced the total LDL subfractions, primarily by reducing the most atherogenic subfraction LDL₅, and reduced CRP but not TNF-α. Explorative analyses suggested that the subfraction LDL₅ during the wash-out period rebounded significantly at least in a per-protocol analysis of the sub-group of patients starting the liraglutide therapy.

CONCLUSIONS

In patients with CAD and newly diagnosed T2DM on stable statin therapy, liraglutide combined with metformin may improve the atherogenic LDL lipid profile and CRP.

The GLP-1 Analogs Liraglutide and Semaglutide Reduce Atherosclerosis in ApoE-/- and LDLr-/- Mice by a Mechanism That Includes Inflammatory Pathways

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The GLP-1RAs liraglutide and semaglutide reduce cardiovascular risk in type 2 diabetes patients.

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In ApoE^−/− mice and LDLr^−/− mice, liraglutide and semaglutide treatment significantly attenuated plaque lesion development, in part independently of body weight and cholesterol lowering.

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Semaglutide decreased levels of plasma markers of systemic inflammation in an acute inflammation model (lipopolysaccharide), and transcriptomic analysis of aortic atherosclerotic tissue revealed that multiple inflammatory pathways were down-regulated by semaglutide.

The glucagon-like peptide-1 receptor agonists (GLP-1RAs) liraglutide and semaglutide reduce cardiovascular risk in type 2 diabetes patients. The mode of action is suggested to occur through modified atherosclerotic progression. In this study, both of the compounds significantly attenuated plaque lesion development in apolipoprotein E-deficient (ApoE^−/−) mice and low-density lipoprotein receptor-deficient (LDLr^−/−) mice. This attenuation was partly independent of weight and cholesterol lowering. In aortic tissue, exposure to a Western diet alters expression of genes in pathways relevant to the pathogenesis of atherosclerosis, including leukocyte recruitment, leukocyte rolling, adhesion/extravasation, cholesterol metabolism, lipid-mediated signaling, extracellular matrix protein turnover, and plaque hemorrhage. Treatment with semaglutide significantly reversed these changes. These data suggest GLP-1RAs affect atherosclerosis through an anti-inflammatory mechanism.

The emerging role of novel antihyperglycemic agents in the treatment of heart failure and diabetes: A focus on cardiorenal outcomes

Heart failure (HF) and type 2 diabetes mellitus (T2DM) are two global pandemics, affecting over 25 and 420 million people, respectively. The prevalence of comorbid HF and T2DM is rising, and the prognosis remains poor. One central area of overlap of these two disease processes is renal dysfunction, which contributes to poor cardiovascular outcomes and mortality. As such, there is a growing need for antihyperglycemic agents with cardio- and renoprotective effects. Three classes of novel antihyperglycemic agents, sodium-glucose cotransporter-2 (SGLT2) inhibitors, glucagon-like peptide-1 receptor agonists (GLP-1RA), and dipeptidyl peptidase-4 (DPP4) inhibitors have demonstrated varied cardiorenal outcomes in recent cardiovascular outcomes trials. Understanding the differential effects of these agents, together with their proposed mechanisms, is crucial for the development of safe and effective treatment regimens and future pharmacologic targets for HF and T2DM. In this review, we discuss the overlapping pathophysiology of HF and T2DM, summarize outcomes data for the novel antihyperglycemic agents and proposed mechanisms of action, and review how the current evidence informs future management of comorbid HF and T2DM.

Cardiovascular benefits of GLP-1 agonists in type 2 diabetes: a comparative review

Type 2 diabetes (T2D) carries risks of both cardiovascular (CV) (myocardial infarction, stroke, and peripheral vascular disease) and microvascular (retinopathy/nephropathy/neuropathy) complications. Glucose-lowering is an effective strategy for preventing microvascular complications, but the extent to which it can reduce CV complications is less certain. Glucagon-like peptide-1 (GLP-1) agonists are potent glucose-lowering agents but also have potentially beneficial effects on other traditional (body weight, blood pressure (BP), and LDL cholesterol) and non-traditional risk factors (low grade inflammation and endothelial dysfunction). The results of four large CV outcome trials with GLP-1 agonists are now available. These have compared lixisenatide (ELIXA), liraglutide (LEADER), semaglutide (SUSTAIN-6), and long-acting exenatide (EXSCEL) with placebo and standard of care over 2–4 years; four others (including with dulaglutide and albiglutide) are ongoing. LEADER and SUSTAIN-6 have demonstrated reductions in rates of major adverse CV events with active GLP-1 treatment but ELIXA and EXSCEL have not. In this review, we discuss the mechanisms by which GLP-1 receptor agonists act on the CV system and the design and conduct of these trials. Contrary to the assertions that (a) all GLP-1 agonists reduce CV disease in T2D but to different extents or (b) the magnitude of CV protection is predominantly related to glucose-lowering, we argue that CV benefit is specific to agents that provide longer acting agonism at the GLP-1 receptor. The mechanisms involve reduction in body weight and BP, and lowering of LDL-cholesterol and glucose, but pleiotropic effects—including suppression of low grade inflammation, vasodilation, and natriuresis—are also likely relevant.

Diabetes, Hypertension, and Cardiovascular Disease: Clinical Insights and Vascular Mechanisms

Hypertension and type 2 diabetes are common comorbidities. Hypertension is twice as frequent in patients with diabetes compared with those who do not have diabetes. Moreover, patients with hypertension often exhibit insulin resistance and are at greater risk of diabetes developing than are normotensive individuals. The major cause of morbidity and mortality in diabetes is cardiovascular disease, which is exacerbated by hypertension. Accordingly, diabetes and hypertension are closely interlinked because of similar risk factors, such as endothelial dysfunction, vascular inflammation, arterial remodelling, atherosclerosis, dyslipidemia, and obesity. There is also substantial overlap in the cardiovascular complications of diabetes and hypertension related primarily to microvascular and macrovascular disease. Common mechanisms, such as upregulation of the renin-angiotensin-aldosterone system, oxidative stress, inflammation, and activation of the immune system likely contribute to the close relationship between diabetes and hypertension. In this article we discuss diabetes and hypertension as comorbidities and discuss the pathophysiological features of vascular complications associated with these conditions. We also highlight some vascular mechanisms that predispose to both conditions, focusing on advanced glycation end products, oxidative stress, inflammation, the immune system, and microRNAs. Finally, we provide some insights into current therapies targeting diabetes and cardiovascular complications and introduce some new agents that may have vasoprotective therapeutic potential in diabetes.

The cardiovascular effect of incretin-based therapies among type 2 diabetes: a systematic review and network meta-analysis

OBJECTIVE

To evaluate the comparative cardiovascular safety of incretin-based therapies in patients with type 2 diabetes mellitus (T2DM).

METHODS

Medline, Embase, the Cochrane Library and www.clinicaltrials.gov were searched for randomized controlled trials (RCTs) with duration≥12 weeks. Network meta-analysis was performed, followed by subgroup analysis and meta-regression. The Grading of Recommendations Assessment, Development and Evaluation system was used to assess the quality of evidence. The outcome of interest was a composite of cardiovascular death, myocardial infarction, stroke and heart failure. Odds ratio (OR) with 95% confidence interval (CI) was calculated as the measure of effect size.

RESULTS

281 RCTs (76.9% double-blinded) with 180,000 patients were included, comparing incretin-based therapies with other six classes of anti-diabetic drugs or placebo. A statistically significant reduction in the risk of cardiovascular events was found in favour of GLP-1RAs when compared with placebo (OR 0.89, 95%CI: 0.80-0.99) and sulfonylurea (OR 0.76, 95%CI: 0.59-0.99), whereas DPP-4 inhibitors showed a neutral effect compared with placebo (OR 0.92, 95%CI: 0.83-1.01).

CONCLUSIONS

Incretin-based therapies show similar cardiovascular risk in comparison with metformin, insulin, thiazolidinediones, alpha-glucosidase inhibitor and sodium-glucose co-transporter 2. GLP-1RA could decrease the risk compared with sulfonylurea or placebo, while DPP-4I appears to have neutral effect on cardiovascular risk.

Effect of liraglutide on atrial natriuretic peptide, adrenomedullin, and copeptin in PCOS

CONTEXT

Women with polycystic ovary syndrome (PCOS) have an increased risk of cardiovascular disease (CVD), and biomarkers can be used to detect early subclinical CVD. Midregional-pro-adrenomedullin (MR-proADM), midregional-pro-atrial natriuretic peptide (MR-proANP) and copeptin are all associated with CVD and part of the delicate system controlling fluid and hemodynamic homeostasis through vascular tonus and diuresis. The GLP-1 receptor agonist liraglutide, developed for treatment of type 2 diabetes (T2D), improves cardiovascular outcomes in patients with T2D including a decrease in particular MR-proANP.

OBJECTIVE

To investigate if treatment with liraglutide in women with PCOS reduces levels of the cardiovascular biomarkers MR-proADM, MR-proANP and copeptin.

METHODS

Seventy-two overweight women with PCOS were treated with 1.8 mg/day liraglutide or placebo for 26 weeks in a placebo-controlled RCT. Biomarkers, anthropometrics, insulin resistance, body composition (DXA) and visceral fat (MRI) were examined.

RESULTS

Baseline median (IQR) levels were as follows: MR-proADM 0.52 (0.45-0.56) nmol/L, MR-proANP 44.8 (34.6-56.7) pmol/L and copeptin 4.95 (3.50-6.50) pmol/L. Mean percentage differences (95% CI) between liraglutide and placebo group after treatment were as follows: MR-proADM -6% (-11 to 2, P = 0.058), MR-proANP -25% (-37 to -11, P = 0.001) and copeptin +4% (-13 to 25, P = 0.64). Reduction in MR-proANP concentration correlated with both increased heart rate and diastolic blood pressure in the liraglutide group. Multiple regression analyses with adjustment for BMI, free testosterone, insulin resistance, visceral fat, heart rate and eGFR showed reductions in MR-proANP to be independently correlated with an increase in the heart rate.

CONCLUSION

In an RCT, liraglutide treatment in women with PCOS reduced levels of the cardiovascular risk biomarkers MR-proANP with 25% and MR-proADM with 6% (borderline significance) compared with placebo. The decrease in MR-proANP was independently associated with an increase in the heart rate.

Liraglutide dictates macrophage phenotype in apolipoprotein E null mice during early atherosclerosis

BACKGROUND

Macrophages play a pivotal role in atherosclerotic plaque development. Recent evidence has suggested the glucagon-like peptide-1 receptor (GLP-1R) agonist, liraglutide, can attenuate pro-inflammatory responses in macrophages. We hypothesized that liraglutide could limit atherosclerosis progression in vivo via modulation of the inflammatory response.

METHODS

Human THP-1 macrophages and bone marrow-derived macrophages, from both wild-type C57BL/6 (WT) and apolipoprotein E null mice (ApoE-/-) were used to investigate the effect of liraglutide on the inflammatory response in vitro. In parallel, ApoE-/- mice were fed a high-fat (60% calories from fat) high-cholesterol (1%) diet for 8 weeks to induce atherosclerotic disease progression with/without daily 300 μg/kg liraglutide administration for the final 6 weeks. Macrophages were analysed for MΦ1 and MΦ2 macrophage markers by Western blotting, RT-qPCR, ELISA and flow cytometry. Atherosclerotic lesions in aortae from ApoE-/- mice were analysed by en face staining and monocyte and macrophage populations from bone marrow derived cells analysed by flow cytometry.

RESULTS

Liraglutide decreased atherosclerotic lesion formation in ApoE-/- mice coincident with a reduction in pro-inflammatory and increased anti-inflammatory monocyte/macrophage populations in vivo. Liraglutide decreased IL-1beta in MΦ0 THP-1 macrophages and bone marrow-derived macrophages from WT mice and induced a significant increase in the MΦ2 surface marker mannose receptor in both MΦ0 and MΦ2 macrophages. Significant reduction in total lesion development was found with once daily 300 μg/kg liraglutide treatment in ApoE-/- mice. Interestingly, liraglutide inhibited disease progression at the iliac bifurcation suggesting that it retards the initiation and development of disease. These results corresponded to attenuated MΦ1 markers (CCR7, IL-6 and TNF-alpha), augmented MΦ2 cell markers (Arg-1, IL-10 and CD163) and finally decreased MΦ1-like monocytes and macrophages from bone marrow-derived cells.

CONCLUSIONS

This data supports a therapeutic role for liraglutide as an atheroprotective agent via modulating macrophage cell fate towards MΦ2 pro-resolving macrophages.

Liraglutide and Renal Outcomes in Type 2 Diabetes

BACKGROUND

In a randomized, controlled trial that compared liraglutide, a glucagon-like peptide 1 analogue, with placebo in patients with type 2 diabetes and high cardiovascular risk who were receiving usual care, we found that liraglutide resulted in lower risks of the primary end point (nonfatal myocardial infarction, nonfatal stroke, or death from cardiovascular causes) and death. However, the long-term effects of liraglutide on renal outcomes in patients with type 2 diabetes are unknown.

METHODS

We report the prespecified secondary renal outcomes of that randomized, controlled trial in which patients were assigned to receive liraglutide or placebo. The secondary renal outcome was a composite of new-onset persistent macroalbuminuria, persistent doubling of the serum creatinine level, end-stage renal disease, or death due to renal disease. The risk of renal outcomes was determined with the use of time-to-event analyses with an intention-to-treat approach. Changes in the estimated glomerular filtration rate and albuminuria were also analyzed.

RESULTS

A total of 9340 patients underwent randomization, and the median follow-up of the patients was 3.84 years. The renal outcome occurred in fewer participants in the liraglutide group than in the placebo group (268 of 4668 patients vs. 337 of 4672; hazard ratio, 0.78; 95% confidence interval [CI], 0.67 to 0.92; P=0.003). This result was driven primarily by the new onset of persistent macroalbuminuria, which occurred in fewer participants in the liraglutide group than in the placebo group (161 vs. 215 patients; hazard ratio, 0.74; 95% CI, 0.60 to 0.91; P=0.004). The rates of renal adverse events were similar in the liraglutide group and the placebo group (15.1 events and 16.5 events per 1000 patient-years), including the rate of acute kidney injury (7.1 and 6.2 events per 1000 patient-years, respectively).

CONCLUSIONS

This prespecified secondary analysis shows that, when added to usual care, liraglutide resulted in lower rates of the development and progression of diabetic kidney disease than placebo. (Funded by Novo Nordisk and the National Institutes of Health; LEADER ClinicalTrials.gov number, NCT01179048 .).