Liraglutide suppresses non-esterified free fatty acids and soluble vascular cell adhesion molecule-1 compared with metformin in patients with recent-onset type 2 diabetes

The Beneficial Effects of GLP-1 Receptor Agonists Other than Their Anti-Diabetic and Anti-Obesity Properties

As an incretin hormone, Glucagon-like peptide-1 (GLP-1) has obvious effects on blood glucose regulation and weight loss. GLP-1 receptor (GLP-1R) agonists are synthetic products that have similar effects to GLP-1 but are less prone to degradation, and they are widely used in the treatment of type 2 diabetes and obesity. In recent years, different beneficial effects of GLP-1R agonists were discovered, such as reducing ischemia-reperfusion injury, improving the function of various organs, alleviating substance use disorder, affecting tumorigenesis, regulating bone metabolism, changing gut microbiota composition, and prolonging graft survival. Therefore, GLP-1R agonists have great potential for clinical application in various diseases. Here, we briefly summarized the beneficial effects of GLP-1R agonists other than the anti-diabetic and anti-obesity effects.

Novel Therapeutics for Type 2 Diabetes Mellitus-A Look at the Past Decade and a Glimpse into the Future

Cardiovascular disease (CVD) and kidney disease are the main causes of morbidity and mortality in type 2 diabetes mellitus (T2DM). Globally, the incidence of T2DM continues to rise. A substantial increase in the burden of CVD and renal disease, alongside the socioeconomic implications, would be anticipated. Adopting a purely glucose-centric approach focusing only on glycemic targets is no longer adequate to mitigate the cardiovascular risks in T2DM. In the past decade, significant advancement has been achieved in expanding the pharmaceutical options for T2DM, with novel agents such as the sodium-glucose cotransporter type 2 (SGLT2) inhibitors and glucagon-like peptide receptor agonists (GLP-1 RAs) demonstrating robust evidence in cardiorenal protection. Combinatorial approaches comprising multiple pharmacotherapies combined in a single agent are an emerging and promising way to not only enhance patient adherence and improve glycemic control but also to achieve the potential synergistic effects for greater cardiorenal protection. In this review, we provide an update on the novel antidiabetic agents in the past decade, with an appraisal of the mechanisms contributing to cardiorenal protection. Additionally, we offer a glimpse into the landscape of T2DM management in the near future by providing a comprehensive summary of upcoming agents in early-phase trials.

A mathematical model of obesity-induced type 2 diabetes and efficacy of anti-diabetic weight reducing drug

The dominant paradigm for modeling the obesity-induced T2DM (type 2 diabetes mellitus) today focuses on glucose and insulin regulatory systems, diabetes pathways, and diagnostic test evaluations. The problem with this approach is that it is not possible to explicitly account for the glucose transport mechanism from the blood to the liver, where the glucose is stored, and from the liver to the blood. This makes it inaccurate, if not incorrect, to properly model the concentration of glucose in the blood in comparison to actual glycated hemoglobin (A1C) test results. In this paper, we develop a mathematical model of glucose dynamics by a system of ODEs. The model includes the mechanism of glucose transport from the blood to the liver, and from the liver to the blood, and explains how obesity is likely to lead to T2DM. We use the model to evaluate the efficacy of an anti-T2DM drug that also reduces weight.

Anti-hyperglycemic effects of propolis or metformin in type 2 diabetes mellitus

Background: The aim of this study was to evaluate the effect of propolis or metformin versus placebo on glycemic control in pharmacological treatment-naïve patients with type 2 diabetes mellitus (T2DM). Methods: A double-blind, randomized, placebo-controlled in parallel groups clinical trial was performed in 36 pharmacological treatment-naïve patients with T2DM. They received propolis (300 mg), metformin (850 mg), or placebo twice daily before breakfast and dinner for 12 weeks. At the beginning and end of the study, fasting plasma glucose (FPG), 2-h postload glucose (2-h PG) during a 75-g oral glucose tolerance test, glycated hemoglobin A1c (A1C) and a metabolic profile were measured. Areas under the curve (AUC) of glucose and insulin, total insulin secretion (insulinogenic index), the first phase of insulin secretion (Stumvoll index), and insulin sensitivity (Matsuda index) were calculated. Statistical analyses: Kruskal-Wallis, Mann-Whitney U and Wilcoxon tests. Results: The propolis and metformin groups exhibited significant reductions in FPG (p=0.009 and p=0.001, respectively), 2-h PG (p=0.034 and p=0.001, respectively) levels, AUC of insulin, Stumvoll index, and an increment in the Matsuda index. The comparison of the changes from baseline to the end showed significant differences between placebo and propolis in FPG (p=0.004) and A1C (p=0.049) levels, while between placebo and metformin were in FPG (p=0.002), 2-h PG (p=0.004) and A1C (p=0.007) levels. Conclusions: The administration of propolis and metformin compared to placebo reduced FPG and A1C levels; in addition, metformin decreased 2-h PG, AUC of glucose and insulin, high-density lipoprotein cholesterol, and increased the insulin sensitivity.

Redefining diabetes mellitus treatments according to different mechanisms beyond hypoglycaemic effect

Early epidemiologic studies in type 2 diabetes suggested that the long-term risk of microvascular and macrovascular complications increase progressively as glucose concentrations rise, inspiring the pursuit of near euglycaemia as a means of preventing these complications in type 1 and type 2 diabetes. Evidence emerging over the past decade, however, showed that the aggressive efforts often needed to achieve low HbA1c levels can ultimately lead to worse clinical outcomes, greater risk of severe hypoglycaemia, and higher burden of treatment. The acknowledgment of the disappointing results obtained with therapies aimed exclusively at improving glycaemic control has led in recent years to a substantial paradigm shift in the treatment of the diabetic patient. The results obtained first with GLP-1RAs and more recently even more with SGLT2i on mortality and CV events have made it clear how other mechanisms, beyond the hypoglycaemic effect, are at the basis of the benefits observed in several cardiovascular outcome trials. And as evidence of the great revolution of thought we are experiencing, there is the recognition of gliflozins as drugs for the treatment not only of diabetic patients but also of non-diabetic patients suffering from HF, as reported in the latest ESC/HFA guidelines. Surely, we still have a lot to understand, but it is certain that this is the beginning of a new era.

Liraglutide Lowers Endothelial Vascular Cell Adhesion Molecule-1 in Murine Atherosclerosis Independent of Glucose Levels

The authors determined the effect of the GLP-1 receptor agonist liraglutide on endothelial surface expression of vascular cell adhesion molecule (VCAM)-1 in murine apolipoprotein E knockout atherosclerosis. Contrast-enhanced ultrasound molecular imaging using microbubbles targeted to VCAM-1 and control microbubbles showed a 3-fold increase in endothelial surface VCAM-1 signal in vehicle-treated animals, whereas in the liraglutide-treated animals the signal ratio remained around 1 throughout the study. Liraglutide had no influence on low-density lipoprotein cholesterol or glycated hemoglobin, but reduced TNF-α, IL-1β, MCP-1, and OPN. Aortic plaque lesion area and luminal VCAM-1 expression on immunohistology were reduced under liraglutide treatment.

Differences in Metabolic Profiles of Healthy Dogs Fed a High-Fat vs. a High-Starch Diet

Obesity is a common problem in dogs and overconsumption of energy-rich foods is a key factor. This study compared the inflammatory response and fecal metabolome of dogs fed a high-fat vs. a high-starch diet. Ten healthy lean adult beagles were equally allocated into two groups in a cross-over design. Each group received two diets in which fat (horse fat) and starch (pregelatinized corn starch) were exchanged in an isocaloric way to compare high fat vs. high starch. There was a tendency to increase the glucose and glycine concentrations and the glucose/insulin ratio in the blood in dogs fed with the high-fat diet, whereas there was a decrease in the level of Non-esterified fatty acids and a tendency to decrease the alanine level in dogs fed with the high-starch diet. Untargeted analysis of the fecal metabolome revealed 10 annotated metabolites of interest, including L-methionine, which showed a higher abundance in dogs fed the high-starch diet. Five other metabolites were upregulated in dogs fed the high-fat diet, but could not be annotated. The obtained results indicate that a high-starch diet, compared to a high-fat diet, may promote lipid metabolism, anti-oxidative effects, protein biosynthesis and catabolism, mucosal barrier function, and immunomodulation in healthy lean dogs.

Effects of GLP-1 receptor agonist on changes in the gut bacterium and the underlying mechanisms

There is a close relationship between the gut microbiota and metabolic disorders. In this study, acute administration of the glucagon-like peptide-1 receptor agonist (GLP-1RA) liraglutide to mice increased the cecal levels of caseinolytic protease B, a component of Escherichia coli, and of norepinephrine. Chemical sympathectomy blocked these events. Norepinephrine was found to pass into the intestinal lumen in vitro. c-Fos staining of the intermediolateral nucleus was identified as indirect evidence of sympathetic nervous system activation of the intestinal tract by GLP-1RA. Under normal conditions, the increase in E. coli did not affect the host. However, in mice with colitis, bacterial translocation was observed with attenuation of tight junction gene expression. This is the first study to investigate the unique underlying mechanisms related the effects of GLP-1RA on changes in the gut bacterium.

Liraglutide treatment improves the coronary microcirculation in insulin resistant Zucker obese rats on a high salt diet

BACKGROUND

Obesity, hypertension and prediabetes contribute greatly to coronary artery disease, heart failure and vascular events, and are the leading cause of mortality and morbidity in developed societies. Salt sensitivity exacerbates endothelial dysfunction. Herein, we investigated the effect of chronic glucagon like peptide-1 (GLP-1) receptor activation on the coronary microcirculation and cardiac remodeling in Zucker rats on a high-salt diet (6% NaCl).

METHODS

Eight-week old Zucker lean (+/+) and obese (fa/fa) rats were treated with vehicle or liraglutide (LIRA) (0.1 mg/kg/day, s.c.) for 8 weeks. Systolic blood pressure (SBP) was measured using tail-cuff method in conscious rats. Myocardial function was assessed by echocardiography. Synchrotron contrast microangiography was then used to investigate coronary arterial vessel function (vessels 50-350 µm internal diameter) in vivo in anesthetized rats. Myocardial gene and protein expression levels of vasoactive factors, inflammatory, oxidative stress and remodeling markers were determined by real-time PCR and Western blotting.

RESULTS

We found that in comparison to the vehicle-treated fa/fa rats, rats treated with LIRA showed significant improvement in acetylcholine-mediated vasodilation in the small arteries and arterioles (< 150 µm diameter). Neither soluble guanylyl cyclase or endothelial NO synthase (eNOS) mRNA levels or total eNOS protein expression in the myocardium were significantly altered by LIRA. However, LIRA downregulated Nox-1 mRNA (p = 0.030) and reduced ET-1 protein (p = 0.044) expression. LIRA significantly attenuated the expressions of proinflammatory and profibrotic associated biomarkers (NF-κB, CD68, IL-1β, TGF-β1, osteopontin) and nitrotyrosine in comparison to fa/fa-Veh rats, but did not attenuate perivascular fibrosis appreciably.

CONCLUSIONS

In a rat model of metabolic syndrome, chronic LIRA treatment improved the capacity for NO-mediated dilation throughout the coronary macro and microcirculations and partially normalized myocardial remodeling independent of changes in body mass or blood glucose.

Nonesterified fatty acids, cognitive decline, and dementia

PURPOSE OF REVIEW

Dementia is rapidly growing as sources of morbidity and mortality as the US population ages, but its pathophysiology remains poorly understood. As a result, no disease-modifying treatments currently exist. We review the evidence that nonesterified fatty acids may play a key role in this condition.

RECENT FINDINGS

Nonesterified fatty acids appear to influence several pathways leading to dementia. In addition to their vascular effects, these moieties cross the blood-brain barrier, where they are toxic to several cell types. They may also influence insulin metabolism in the brain directly and indirectly, and some drugs that lower circulating levels appear to slow cognitive decline and brain atrophy in diabetes.

SUMMARY

Nonesterified fatty acids may contribute to dementia, much as they do to diabetes and cardiovascular disease. Several therapeutic agents lower circulating levels of nonesterified fatty acids and should be tested for their potential preventive effects on cognitive decline in healthy populations before irreversible neuronal attrition occurs.

Liraglutide improves lipid metabolism by enhancing cholesterol efflux associated with ABCA1 and ERK1/2 pathway

BACKGROUND

Reverse cholesterol transport (RCT) is an important cardioprotective mechanism and the decrease in cholesterol efflux can result in the dyslipidemia. Although liraglutide, a glucagon like peptide-1 analogue, has mainly impacted blood glucose, recent data has also suggested a beneficial effect on blood lipid. However, the exact mechanism by which liraglutide modulates lipid metabolism, especially its effect on RCT, remain undetermined. Hence, the aim of the present study was to investigate the potential impacts and potential underlying mechanisms of liraglutide on the cholesterol efflux in both db/db mice and HepG2 cells.

METHODS

Six-week old db/db mice with high fat diet (HFD) and wild type mice were administered either liraglutide (200 μg/kg) or equivoluminal saline subcutaneously, twice daily for 8 weeks and body weight was measured every week. After the 8-week treatment, the blood was collected for lipid evaluation and liver was obtained from the mice for hematoxylin-eosin (HE) staining, red O staining and Western blotting. Cholesterol efflux was assessed by measuring the radioactivity in the plasma and feces after intraperitoneal injection of 3H-labeled cholesterol. HepG2 Cells were treated with different concentrations of glucose (0, 5, 25, and 50 mmol/L) with or without liraglutide (1000 nmol/L) for 24 h. The intracellular cholesterol efflux was detected by BODIPY-cholesterol fluorescence labeling. Real-time PCR or Western blotting was used to examine the expression levels of ABCA1, ABCG1 and SR-B1.

RESULTS

Liraglutide significantly decreased blood glucose, serum total cholesterol (TC), triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C). It also reduced liver lipid deposition in db/db mice fed with HFD. Moreover, the movement of 3H-cholesterol from macrophages to plasma and feces was significantly enhanced in db/db mice fed with HFD after liraglutide adminstration. In vitro study, liraglutide could promote the cholesterol efflux of HepG2 cells under high glucose, and also increase the expression of ABCA1 by activating the ERK1/2 pathway.

CONCLUSIONS

Liraglutide could improve lipid metabolism and hepatic lipid accumulation in db/db mice fed with HFD by promoting reversal of cholesterol transport, which was associated with the up-regulation of ABCA1 mediated by the ERK1/2 phosphorylation.

Short-term treatment with high dose liraglutide improves lipid and lipoprotein profile and changes hormonal mediators of lipid metabolism in obese patients with no overt type 2 diabetes mellitus: a randomized, placebo-controlled, cross-over, double-blind clinical trial

OBJECTIVE

Long-term treatment with up to 1.8 mg liraglutide improves cardiovascular and all-cause mortality in patients with type 2 diabetes at high risk for cardiovascular disease (CVD) and is currently under investigation in subjects without diabetes. Aim of our study was to investigate whether high dose (3 mg) short-term (5 weeks) treatment with liraglutide in obese patients with no overt type 2 diabetes affects metabolites, lipid and lipoprotein profile and components of activin-follistatin axis in cardiovascular beneficial or detrimental way.

RESEARCH DESIGN AND METHODS

Twenty obese patients participated in a randomized, placebo-controlled, cross-over, double-blind study and were administrated liraglutide 3 mg or placebo for 5 weeks. Metabolites, fatty acids, lipid-lipoprotein profile and concentrations of activins and follistatins (250 parameters) were assessed in serum at start and completion of each treatment.

RESULTS

Concentrations of important cardiovascular markers such as total, free and remnant cholesterol were reduced with liraglutide before and after adjusting for weight loss. Similarly, reductions in number of small and medium size LDL particles and in their total lipid concentration were observed with liraglutide and partially weight-loss related. Tyrosine levels were reduced and behenic acid levels were increased whereas only minor changes were observed in HDL, VLDL and IDL. Concentrations of activin AB and follistatin were significantly reduced in liraglutide-treated group.

CONCLUSIONS

Treatment of obese patients without overt type 2 diabetes with high dose of liraglutide for a short period of time induces changes in lipid-lipoprotein and hormonal profile that are suggestive of lower risk of atherosclerosis and CVD. Trial registration ClinicalTrials.gov Identifier: NCT02944500. Study ID Number 2015P000327. Registered November 2016.

Impact of free fatty acids on prognosis in coronary artery disease patients under different glucose metabolism status

BACKGROUND

The aim of the present study is to examine the effects of free fatty acids (FFAs) on major cardiovascular events (MACEs) in patients with stable coronary artery disease (CAD) and different glucose metabolism status.

METHODS

In this study, we consecutively enrolled 5443 patients from March 2011 to May 2015. Patients were categorized according to both status of glucose metabolism status [diabetes mellitus (DM), pre-diabetes (Pre-DM), normal glycaemia regulation (NGR)] and FFAs levels. All subjects were followed up for the occurrence of the MACEs.

RESULTS

During a median of 6.7 years' follow-up, 608 MACEs occurred. A twofold higher FFAs level was independently associated with MACEs after adjusting for confounding factors [Hazard Ratio (HR): 1.242, 95% confidence interval (CI) 1.084-1.424, p value = 0.002]. Adding FFAs to the Cox model increased the C-statistic by 0.015 (0.005-0.027). No significant difference in MACEs was observed between NGR and Pre-DM groups (p > 0.05). When patients were categorized by both status of glucose metabolism and FFAs levels, medium and high FFAs were associated with significantly higher risk of MACEs in Pre-DM [1.736 (1.018-2.959) and 1.779 (1.012-3.126), all p-value < 0.05] and DM [2.017 (1.164-3.494) and 2.795 (1.619-4.824), all p-value < 0.05].

CONCLUSIONS

The present data indicated that baseline FFAs levels were associated with the prognosis in DM and Pre-DM patients with CAD, suggesting that FFAs may be a valuable predictor in patients with impaired glucose metabolism.

Cardiovascular outcomes in trials of new antidiabetic drug classes: a network meta-analysis

BACKGROUND

Recent trials suggested that glucagon-like peptide-1 receptor agonists (GLP-1 RAs) and sodium-glucose co-transporter-2 (SGLT-2) inhibitors reduced cardiovascular events. Comparative effectiveness of these new antidiabetic drug classes remains unclear. We therefore performed a network meta-analysis to compare the effect on cardiovascular outcomes among GLP-1 RAs, SGLT-2 and dipeptidyl peptidase-4 (DPP-4) inhibitors.

METHODS

MEDLINE, EMBASE, Cochrane database, ClinicalTrials.gov, and congress proceedings from recent cardiology conferences were searched up to April 20, 2019. Cardiovascular outcome trials and renal outcome trials reporting cardiovascular outcomes on GLP-1 RAs, SGLT-2 and DPP-4 inhibitors in patients with type 2 diabetes mellitus were included. The primary outcome was major adverse cardiovascular events (MACE). Secondary outcomes were nonfatal myocardial infarction, nonfatal stroke, cardiovascular mortality, all-cause mortality, hospitalisation for heart failure (HF), and renal composite outcome. ORs and 95% CI were calculated using random-effects models.

RESULTS

Fourteen trials enrolling 121,047 patients were included. SGLT-2 inhibitors reduced cardiovascular deaths and all-cause deaths compared to placebo (OR 0.82, 95% CI 0.73-0.93 and OR 0.84, 95% CI 0.77-0.92) and DPP-4 inhibitors (OR 0.83, 95% CI 0.70-0.99 and OR 0.83, 95% CI 0.73-0.94), respectively. SGLT-2 inhibitors and GLP-1 RAs significantly reduced MACE (OR 0.88, 95% CI 0.82-0.95 and OR 0.87, 95% CI 0.82-0.93), hospitalisation for HF (OR 0.68, 95% CI 0.61-0.77 and OR 0.87, 95% CI 0.82-0.93), and renal composite outcome (OR 0.59, 95% CI 0.52-0.67 and OR 0.86, 95% CI 0.78-0.94) compared to placebo, but SGLT-2 inhibitors reduced hospitalisation for HF (OR 0.79, 95% CI 0.69-0.90) and renal composite outcome (OR 0.69, 95% CI 0.59-0.80) more than GLP-1 RAs. Only GLP-1 RAs reduced nonfatal stroke (OR 0.88, 95% CI 0.77-0.99). DPP-4 inhibitors did not lower the risk of these outcomes when compared to placebo and were associated with higher risks of MACE, hospitalisation for HF, and renal composite outcome when compared to the other two drug classes.

CONCLUSIONS

SGLT-2 inhibitors show clear superiority in reducing cardiovascular and all-cause deaths, hospitalisation for HF, and renal events among new antidiabetic drug classes. GLP-1 RAs also have cardiovascular and renal protective effects. DPP-4 inhibitors have no beneficial cardiovascular effects and are therefore inferior to the other two drug classes. SGLT-2 inhibitors should now be the preferred treatment for type 2 diabetes mellitus.

Metformin in patients with and without diabetes: a paradigm shift in cardiovascular disease management

With an increasing global burden of coronary artery disease (CAD), early detection and timely management of risk factors are crucial to reduce morbidity and mortality in such patients. Diabetes mellitus (DM) is considered an independent risk factor for the development of CAD. Metformin, an anti-diabetic drug, has been shown in pre-clinical and clinical studies, to lower the cardiovascular events in the DM patients. Growing evidence suggests that metformin has a protective effect on coronary artery beyond its hypoglycemic effects. Given its global availability, route of administration and cost, metformin provides an alternate/additional therapeutic option for primary and secondary prevention of CAD in DM and non-diabetics alike. Future prospective cohort-based studies and randomized clinical trials are needed to identify 'at-risk' population who may potentially benefit from metformin.

Liraglutide ameliorates beta-cell function, alleviates oxidative stress and inhibits low grade inflammation in young patients with new-onset type 2 diabetes

BACKGROUND

The prevalence of type 2 diabetes in youth is escalating rapidly. We aimed to evaluate the effects of liraglutide on beta-cell function, metabolic productions of oxidative stress, low grade inflammation compared with metformin in young patients with recent onset type 2 diabetes mellitus.

METHODS

Sixty patients were randomly assigned to receive 8-week liraglutide or metformin treatment. Beta-cell function was assessed by modified beta cell function index (MBCI), early phase of insulin secretion index (ΔI30/ΔG30), proinsuin to insulin ratio (P/I) and the insulin area under the curve (AUCins). The expression of 8-OH-dG and 8-iso-PGF_2α and hs-C-reactive protein (hs-CRP) were measured as indications of oxidative stress and low grade inflammation.

RESULTS

After 8 weeks liraglutide treatment, MBCI, ΔI30/ΔG30, AUCins significantly increased, 8-OH-dG, 8-iso-PGF_2α, P/I and hs-CRP remarkably reduced. The differences before and after 8-week liraglutide treatment in ΔMBCI (11.1 [2.81, 43.08] vs 0.00 [- 8.16, 10.47], P = 0.017), ΔLNΔI30/ΔG30 (0.44 [0.04, 0.85] vs - 0.09 [- 0.33, 0.36], P = 0.049), ΔAUCins (117 [- 8, 376] vs - 21 [- 314, 109] mIU/L, P = 0.013), ΔP/I (- 0.05 [- 0.09, - 0.03] vs - 0.02 [- 0.04, 0.01], P = 0.026)were remarkably enhanced compared to those of the metformin therapy. The expression of 8-OH-dG, 8-iso-PGF_2α and hs-CRP also decreased after 8-week metformin treatment.

CONCLUSIONS

These data demonstrated that liraglutide administration was more effective on ameliorating beta-cell function than metformin treatment in young patients with new-onset type 2 diabetes mellitus. Both liraglutide and metformin could alleviate the level of oxidative stress and attenuate low grade inflammatory, we speculate this effect may not the main mechanism of beta-cell function improvement by liraglutide in diabetic patients.Trial registration Chinese Clinical Trials registry, chiCTR1800018008, Registered 27 August 2018-retrospectively registered.