Exenatide improves diastolic function and attenuates arterial stiffness but does not alter exercise capacity in individuals with type 2 diabetes

The effect of SGLT2 inhibitors and GLP1 receptor agonists on arterial stiffness: A meta-analysis of randomized controlled trials

BACKGROUND

Pulse wave velocity (PWV) and augmentation index (AIx) are indices used to assess arterial stiffness. We evaluated the effect of sodium glucose co-transporter-2 inhibitors (SGLT2i) and glucagon-like peptide-1 receptor agonists (GLP1-RA) on arterial stiffness indices.

METHODS

We searched PubMed (up to January 2024) for RCTs assessing the effect of SGLT2i or GLP1-RA on arterial stiffness with reporting outcomes PWV and AIx. Effect sizes of the included studies were expressed as weighted mean difference (WMD) and 95 % confidence interval. Subgroup analyses were performed based on comparator (placebo vs. active comparator), design (RCT vs. crossover), population (diabetic vs. all) and blindness (yes vs. no).

RESULTS

A total of 19 studies (SGLT2i, 12 studies; GLP1-RA, 5 studies; SGLT2i/GLP1-RA combination, 2 studies) assessing 1212 participants were included. We did not find any statistically significant association between GLP1-RA or SGLT2i and PWV or AIx. None of the subgroup analyses showed any statistically significant result.

CONCLUSION

No evidence of a favorable change in arterial stiffness indices (PWV, AIx) was found following the administration of SGLT2i or GLP1-RA.

Glucagon-Like Peptide-1 Receptor Agonists and Sodium Glucose Cotransporter-2 Inhibitors and Cardiorespiratory Fitness Interaction

INTRODUCTION

Cardiorespiratory fitness (CRF) is a stronger predictor of mortality than traditional risk factors and is a neglected vital sign of health. Enhanced fitness is a cornerstone in diabetes management and is most often delivered concurrently with pharmacological agents, which can have an opposing impact, as has been reported with metformin. Considering the rapid evolution of diabetes medications with improved cardiovascular outcomes, such as glucagon-like peptide-1 receptor agonists and sodium glucose cotransporter-2 inhibitors, it is of importance to consider the influence of these vis-a-vis effects on CRF.

MATERIALS AND METHODS

Combining the words glucagon-like peptide-1 receptor agonists and sodium glucose cotransporter-2 inhibitors with cardiorespiratory fitness, an online search was done using PubMed, Embase, Scopus, Web of Science, Scientific Electronic Library Online, and Cochrane.

RESULTS

There were only a few randomized controlled studies that included CRF, and the results were mostly neutral. A handful of smaller studies detected improved CRF using sodium glucose cotransporter-2 inhibitors in patients with congestive heart failure.

CONCLUSIONS

Since CRF is a superior prognosticator for cardiovascular outcomes and both medications can cause lean muscle mass loss, the current review highlights the paucity of relevant interactive analysis.

The effect of glucagon-like peptide-1 receptor agonists on cardiac function and structure in patients with or without type 2 diabetes mellitus: An updated systematic review and meta-analysis

AIMS

To conduct an updated systematic review and meta-analysis to evaluate the efficacy of glucagon-like peptide-1 receptor agonists (GLP-1RAs) with regard to cardiac function and structure in people with or without type 2 diabetes mellitus (T2DM).

MATERIALS AND METHODS

We conducted a systematic search using the PubMed, Embase and ClinicalTrials.gov online databases. The primary outcome of interest was changes in mitral inflow E-velocity to tissue Doppler e' velocity (E/e') ratio. Secondary outcomes included other indicators of cardiac reverse remodelling and functional capacity comprising changes in left ventricular mass (LVM), left ventricular global longitudinal strain, left ventricular end-diastolic volume, left ventricular end-systolic volume, left ventricular ejection fraction (LVEF), early to atrial mitral inflow velocity ratio, left atrial volume (LAV), N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels and 6-min walk test (6MWT) results.

RESULTS

A total of 15 trials involving 898 patients were included in this analysis. GLP-1RAs significantly improved E/e' ratio (mean difference [MD] = -0.73; 95% confidence interval [CI] -1.34, -0.13), LVM (MD = -3.86 g; 95% CI -7.60, -0.12), LAV (MD = -8.20 mL; 95% CI -12.37, -4.04), NT-proBNP level (standardized MD = -0.27; 95% CI -0.47, -0.06), and 6MWT result (MD = +22.31 m; 95% CI 1.64, 42.99). However, GLP-1RAs had no effect on LVEF (MD = +0.31%; 95% CI -1.02, 1.64).

CONCLUSIONS

In this systematic review and meta-analysis, GLP-1RAs were found to have a positive impact on left ventricle diastolic function, hypertrophy, and exercise capacity, but had no effect on systolic function.

Separate and combined effects of empagliflozin and semaglutide on vascular function: A 32-week randomized trial

AIM

Despite the increasing use of combination treatment with sodium-glucose cotransporter 2 inhibitors and glucagon-like peptide-1 receptor agonists, data are limited on the effects of combination treatment on markers of cardiovascular disease. This study aimed to investigate the effect of empagliflozin, semaglutide, and their combination on vascular function.

MATERIALS AND METHODS

In total, 120 patients with type 2 diabetes were randomized into four groups (n = 30 in each) for 32 weeks: placebo, semaglutide, empagliflozin, and their combination. The study had two co-primary outcomes: change in arterial stiffness and kidney oxygenation. This paper reports on arterial stiffness assessed as carotid-femoral pulse wave velocity. Secondary outcomes included 24-h blood pressure (BP), 24-h central BP, urinary albumin to creatinine ratio and glycaemic control assessed by both continuous glucose monitoring and glycated haemoglobin.

RESULTS

The carotid-femoral pulse wave velocity did not change significantly in any of the groups compared with placebo. Twenty-four-hour systolic BP was reduced by 10 mmHg (95% CI 6-14), p < .001 in the combination group, significantly superior to both placebo and monotherapy (p < .05). Combination treatment increased glycaemic time in range from 72% at baseline to 91% at week 32, p < .001, without increasing time below range. The urinary albumin to creatinine ratio decreased by 36% (95% CI 4-57), p = .03 in the combination group compared with placebo.

CONCLUSIONS

Empagliflozin, semaglutide, or their combination did not reduce arterial stiffness. Combination treatment showed a substantial and clinically important reduction in 24-h systolic BP compared with either treatment alone. Combination treatment increased glycaemic time in range without increasing the risk of hypoglycaemia.

Effects of Glucagon-Like Peptide-1 Receptor Agonist (GLP-1RA) on Cardiac Structure and Function: A Systematic Review and Meta-Analysis of Randomized-Controlled Trials

PURPOSE

Recent trials suggest glucagon-like peptide-1 receptor agonists (GLP-1RAs) may have a cardioprotective role by reducing major adverse cardiac events, stroke mortality and heart failure-related hospitalisations. We examined whether and how GLP-1RAs affect cardiac function in cardiovascular and metabolic diseases including type 2 diabetes, heart failure and post-myocardial infarction.

METHODS

In this PRISMA-adherent systematic review and meta-analysis, three databases were searched from inception to July 2021 and registered on PROSPERO (CRD42021259661).

RESULTS

20 reports of 19 randomized placebo-controlled trials including 2062 participants were meta-analyzed. Among type 2 diabetes patients, GLP-1RA resulted in improved systolic function measured by circumferential strain (mean difference [MD]= -5.48; 95% CI: -10.47 to -0.49; P= 0.03; I2= 89%) and diastolic dysfunction measured by E / A (MD= -0.15; 95% CI: -0.25 to -0.05; P= 0.003; I2= 0%). For post-myocardial infarction patients, GLP-1RA reduced infarct size (g) (MD= -5.36; 95% CI: -10.68 to -0.04; P= 0.05; I2= 78%). Liraglutide, but not exenatide, demonstrated improved systolic function, by increasing left ventricular ejection fraction (MD= 4.89; 95% CI: 3.62 to 6.16; P< 0.00001; I2= 0%) and reducing left ventricular end-systolic volume (MD= -4.15; 95% CI: -7.49 to -0.81; P = 0.01; I2= 0%). Among heart failure patients, no significant changes were noted.

CONCLUSION

GLP-1RA drugs may improve systolic and diastolic function in type 2 diabetes and reduce infarct size post-acute myocardial infarction with no demonstrable effect on cardiac function in heart failure. Tailored recommendations for the use of GLP-1RAs for cardioprotection should be considered for each patient's condition.

Obesity dominates early effects on cardiac structure and arterial stiffness in people with type 2 diabetes

OBJECTIVE

Type 2 diabetes (T2D) and obesity are global epidemics leading to excess cardiovascular disease (CVD). This study investigates standard and novel cardiac MRI parameters to detect subclinical cardiac and central vascular dysfunction in inactive people with and without T2D.

METHODS

Physically inactive age and BMI-similar premenopausal women and men with ( n  = 22) and without [ n  = 34, controls with overweight/obesity (CWO)] uncomplicated T2D were compared to an age-similar and sex-similar reference control cohort ( n  = 20). Left ventricular (LV) structure, function, and aortic stiffness were assessed by MRI. Global arterial pulse wave velocity (PWV) was assessed using carotid-to-femoral applanation tonometry. Regional PWV was measured via 2D phase-contrast MRI and 4D flow MRI.

RESULTS

Global arterial PWV did not differ between CWO and T2D. 2D PC-MRI PWV in the ascending aorta was higher in people with T2D compared with CWOs ( P  < 0.01). 4D flow PWV in the thoracic aorta was higher in CWO ( P  < 0.01), and T2D ( P  < 0.001) compared with RC. End-diastolic volume, end-systolic volume, stroke volume, and cardiac output were lower in CWO and T2D groups compared with reference control.

CONCLUSION

Subclinical changes in arterial stiffening and cardiac remodeling in inactive CWO and T2D compared with reference control support obesity and/or physical inactivity as determinants of incipient CVD complications in uncomplicated T2D. Future studies should determine the mechanistic causes of the CVD complications in greater detail in order to create therapeutic targets.

CLINICAL TRIAL REGISTRATION

Cardiovascular Mechanisms of Exercise Intolerance in Diabetes and the Role of Sex (NCT03419195).

The Cardioprotective Effects of Semaglutide Exceed Those of Dietary Weight Loss in Mice With HFpEF

Obesity-related heart failure with preserved ejection fraction (HFpEF) has become a well-recognized HFpEF subphenotype. Targeting the unfavorable cardiometabolic profile may represent a rational treatment strategy. This study investigated semaglutide, a glucagon-like peptide-1 receptor agonist that induces significant weight loss in patients with obesity and/or type 2 diabetes mellitus and has been associated with improved cardiovascular outcomes. In a mouse model of HFpEF that was caused by advanced aging, female sex, obesity, and type 2 diabetes mellitus, semaglutide, compared with weight loss induced by pair feeding, improved the cardiometabolic profile, cardiac structure, and cardiac function. Mechanistically, transcriptomic, and proteomic analyses revealed that semaglutide improved left ventricular cytoskeleton function and endothelial function and restores protective immune responses in visceral adipose tissue. Strikingly, treatment with semaglutide induced a wide array of favorable cardiometabolic effects beyond the effect of weight loss by pair feeding. Glucagon-like peptide-1 receptor agonists may therefore represent an important novel therapeutic option for treatment of HFpEF, especially when obesity-related.

Effects of Incretin-Based Treatment on the Diastolic (Dys)Function in Patients with Uncontrolled Type 2 Diabetes Mellitus: A Prospective Study with 1-Year Follow-Up

Left ventricular diastolic dysfunction (DD) is a subclinical cardiac abnormality in patients with type 2 diabetes mellitus (T2DM) that can progress to heart failure (HF) and increase cardiovascular risk. This prospective study evaluated the DD in T2DM patients without atherosclerotic cardiovascular disease after one year of incretin-based drugs added to standard treatment. Of the 138 enrolled patients (49.30% male, mean age 57.86 ± 8.82, mean T2DM history 5 years), 71 were started on dipeptidyl peptidase-4 inhibitor sitagliptin/saxagliptin, 21 on glucagon-like peptide-1 receptor agonist exenatide, and 46 formed the control group (metformin and sulphonylurea/acarbose). At baseline, 71 patients had grade 1 DD, another 12 had grade 2 and 3 DD, and 15 had indeterminate DD. After one year, DD was evidenced in 50 cases. Diastolic function improved in 9 cases, and 27 patients went from grade 1 to indeterminate DD. The active group benefited more, especially patients treated with exenatide; their metabolic and inflammation profiles also improved the most. An in-depth analysis of echocardiographic parameters and paraclinical results in the context of literature data justifies the conclusion that early assessment of diastolic function in T2DM patients is necessary and the benefits of affordable incretin-based treatment may extend to subclinical cardiovascular manifestations such as DD.

Vascular Aging: Assessment and Intervention

Vascular aging represents a collection of structural and functional changes in a blood vessel with advancing age, including increased stiffness, vascular wall remodeling, loss of angiogenic ability, and endothelium-dependent vasodilation dysfunction. These age-related alterations may occur earlier in those who are at risk for or have cardiovascular diseases, therefore, are defined as early or premature vascular aging. Vascular aging contributes independently to cardio-cerebral vascular diseases (CCVDs). Thus, early diagnosis and interventions targeting vascular aging are of paramount importance in the delay or prevention of CCVDs. Here, we review the direct assessment of vascular aging by examining parameters that reflect changes in structure, function, or their compliance with age including arterial wall thickness and lumen diameter, endothelium-dependent vasodilation, arterial stiffness as well as indirect assessment through pathological studies of biomarkers including endothelial progenitor cell, lymphocytic telomeres, advanced glycation end-products, and C-reactive protein. Further, we evaluate how different types of interventions including lifestyle mediation, such as caloric restriction and salt intake, and treatments for hypertension, diabetes, and hyperlipidemia affect age-related vascular changes. As a single parameter or intervention targets only a certain vascular physiological change, it is recommended to use multiple parameters to evaluate and design intervention approaches accordingly to prevent systemic vascular aging in clinical practices or population-based studies.

The effect of exenatide (a GLP-1 analogue) and sitagliptin (a DPP-4 inhibitor) on asymmetric dimethylarginine (ADMA) metabolism and selected biomarkers of cardiac fibrosis in rats with fructose-induced metabolic syndrome

Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide (NO) synthesis, is a risk factor for endothelial dysfunction, a common pathophysiological denominator for both atherogenesis and cardiac fibrosis. We aimed to investigate whether the cardioprotective and antifibrotic effects of incretin drugs, exenatide and sitagliptin, may be associated with their ability to affect circulating and cardiac ADMA metabolism. Normal and fructose-fed rats were treated with sitagliptin (5.0/10 mg/kg) or exenatide (5/10 µg/kg) for 4 weeks. The following methods were used: LC-MS/MS, ELISA, Real-Time-PCR, colorimetry, IHC and H&E staining, PCA and OPLS-DA projections. Eight-week fructose feeding resulted in an increase in plasma ADMA and a decrease in NO concentration. Exenatide administration into fructose-fed rats reduced the plasma ADMA level and increased NO level. In the heart of these animals exenatide administration increased NO and PRMT1 level, reduced TGF-ß1, α-SMA levels and COL1A1 expression. In the exenatide treated rats renal DDAH activity positively correlated with plasma NO level and negatively with plasma ADMA level and cardiac α-SMA concentration. Sitagliptin treatment of fructose-fed rats increased plasma NO concentration, reduced circulating SDMA level, increased renal DDAH activity and reduced myocardial DDAH activity. Both drugs attenuated the myocardial immunoexpression of Smad2/3/P and perivascular fibrosis. In the metabolic syndrome condition both sitagliptin and exenatide positively modulated cardiac fibrotic remodeling and circulating level of endogenous NOS inhibitors but had no effects on ADMA levels in the myocardium.

Multifaceted Roles of GLP-1 and Its Analogs: A Review on Molecular Mechanisms with a Cardiotherapeutic Perspective

Diabetes is one of the chronic metabolic disorders which poses a multitude of life-debilitating challenges, including cardiac muscle impairment, which eventually results in heart failure. The incretin hormone glucagon-like peptide-1 (GLP-1) has gained distinct recognition in reinstating glucose homeostasis in diabetes, while it is now largely accepted that it has an array of biological effects in the body. Several lines of evidence have revealed that GLP-1 and its analogs possess cardioprotective effects by various mechanisms related to cardiac contractility, myocardial glucose uptake, cardiac oxidative stress and ischemia/reperfusion injury, and mitochondrial homeostasis. Upon binding to GLP-1 receptor (GLP-1R), GLP-1 and its analogs exert their effects via adenylyl cyclase-mediated cAMP elevation and subsequent activation of cAMP-dependent protein kinase(s) which stimulates the insulin release in conjunction with enhanced Ca²⁺ and ATP levels. Recent findings have suggested additional downstream molecular pathways stirred by long-term exposure of GLP-1 analogs, which pave the way for the development of potential therapeutic molecules with longer lasting beneficial effects against diabetic cardiomyopathies. This review provides a comprehensive overview of the recent advances in the understanding of the GLP-1R-dependent and -independent actions of GLP-1 and its analogs in the protection against cardiomyopathies.

The effects of weight-lowering pharmacotherapies on physical activity, function and fitness: A systematic review and meta-analysis of randomized controlled trials

Weight-lowering pharmacotherapies provide an option for weight management; however, their effects on physical activity, function, and cardiorespiratory fitness are not fully understood. We conducted a systematic review and meta-analysis of randomized controlled trials to investigate the effect of licensed weight loss pharmacotherapies on physical activity, physical function, and cardiorespiratory fitness in individuals with obesity. Fourteen trials met our prespecified inclusion criteria: Five investigated liraglutide, four semaglutide, three naltrexone/bupropion, and two phentermine/topiramate. All 14 trials included a self-reported measure of physical function, with the pooled findings suggesting an improvement favoring the pharmacotherapy intervention groups (SMD: 0.27; 95% CI: 0.22 to 0.32) and effects generally consistent across different therapies. Results were also consistent when stratified by the two most commonly used measures: The Short-Form 36-Item Questionnaire (SF-36) (0.24; 0.17 to 0.32) and the Impact of Weight on Quality Of Life-Lite (IWQOL-Lite) (0.29; 0.23 to 0.35). Meta-regression confirmed a significant association between pharmacotherapy induced weight loss and improved physical function for IWQOL-Lite (p = 0.003). None of the studies reported a physical activity outcome, and only one study reported objectively measured cardiorespiratory fitness. Improvements in self-reported physical function were observed with weight loss therapy, but the effect on physical activity or objectively measured physical function and fitness could not be determined.

The effect of SGLT2 inhibitors, GLP1 agonists, and their sequential combination on cardiometabolic parameters: A randomized, prospective, intervention study

BACKGROUND

Pulse wave velocity (PWV) and augmentation index (AIx) are indices used to assess arterial stiffness. We aim to compare the effect of empagliflozin, liraglutide and their sequential combination on arterial stiffness indices in patients with type 2 diabetes (T2D).

METHODS

This was a randomized single blind study evaluating the effect of empagliflozin vs liraglutide in adult patients with T2D. Patients were randomized to liraglutide titrated gradually to 1.8 mg or empagliflozin 25 mg in 1:1 ratio. Three months later empagliflozin was added to the liraglutide group, and liraglutide was added to the empagliflozin group. Patients were assessed with non-invasive tests for arterial stiffness (i.e., carotid-femoral PWV and AIx of aortic pressure) at baseline, 3-month and 9-month visits (final visit was extended for 3 months from the initial design due to Covid 19 pandemic). The primary outcome was the between-group difference of PWV change (ΔPWV) and ΔAIx at 3 months. Secondary outcomes included the between-group difference of ΔPWV and ΔAIx at 9 months, as well as the ΔPWV and ΔAIx between baseline and 9-month visit when total study population was assessed.

RESULTS

A total of 62 patients with T2D (30 started liraglutide; 32 empagliflozin, mean age 63 years, 25 % with established cardiovascular disease) participated in the study. We failed to show any significant between-group differences of ΔPWV and ΔΑΙx at 3 and 9 months, as well as between-group difference of ΔPWV and ΔAIx for the total study population between baseline and 9-month visit. In contrast, systemic vascular resistance and lipoprotein(a) levels improved, showing better results with liraglutide than empagliflozin. Favorable effects were also observed on body weight, body mass index, body and visceral fat, blood pressure, HbA1c, and uric acid levels.

CONCLUSION

No evidence of a favorable change in arterial stiffness indices was seen with empagliflozin or liraglutide or their combination in this study. Well-designed powerful studies are needed to address any potential effects on arterial stiffness in selected populations.

Impact of novel glucose-lowering therapies on physical function in people with type 2 diabetes: A systematic review and meta-analysis of randomised placebo-controlled trials

AIMS

We investigated evidence from randomised, placebo-controlled trials of novel glucose-lowering therapies; sodium-glucose co-transporter-2 inhibitors (SGLT2i), dipeptidyl peptidase-4 inhibitors (DPP4i) and glucagon-like peptide-1 receptor agonists (GLP-1RA), on physical function in people with type 2 diabetes (T2D).

METHODS

PubMed, Medline, Embase and Cochrane library were searched from 1 April 2005 to 20 January 2022. The primary outcome was change in physical function in groups receiving a novel glucose-lowering therapy versus placebo at the trial end-point.

RESULTS

Eleven studies met our criteria including nine for GLP-1RA and one each for SGLT2i and DPP4i. Eight studies included a self-reported measure of physical function, seven with GLP-1RA. Pooled meta-analysis showed an improvement of 0.12 (0.07, 017) points in favour of novel glucose-lowering therapies, mainly GLP-1RA. These findings were consistent when assessed individually for commonly used subjective assessments of physical function; namely the Short-Form 36 item-questionnaire (SF-36; all investigating GLP-1RA) and the Impact of Weight on Quality of Life-Lite (IWQOL-LITE; all, except one, exploring GLP-1RA) with estimated treatment differences (ETDs) of 0.86 (0.28, 1.45) and 3.72 (2.30, 5.15) respectively in favour of novel GLTs. For objective measures of physical function (VO_2max and 6-minute walk test (6MWT)) no significant between-group differences between the intervention and the placebo were found.

CONCLUSIONS

GLP-1RAs showed improvements in self-reported outcomes of physical function. However, there is limited evidence to draw definitive conclusions especially because of lack of studies exploring the impact of SGLT2i and DPP4i on physical function. There is a need for dedicated trials to establish the association between novel agents and physical function.

Effect of Glucagon-like Peptide-1 Receptor Agonists on Prognosis of Heart Failure and Cardiac Function: A Systematic Review and Meta-analysis of Randomized Controlled Trials

PURPOSE

Whether an antidiabetic drug, glucagon-like peptide-1 receptor agonist (GLP-1RA), could improve the prognosis of heart failure and cardiac function remains controversial. We conducted a systematic review and meta-analysis of randomized controlled trials to explore the influence of GLP-1RAs on heart failure in patients regardless of diabetes diagnosis.

METHODS

Literature in English from the PubMed, EMBASE, and Cochrane Library databases was searched from inception to July 2022. The study aim was to identify published, randomized, placebo-controlled trials testing GLP-1RAs in patients with or without diabetes. Outcomes were heart failure hospitalization, cardiac function, and structure measures.

FINDINGS

Twenty-two randomized controlled trials involving 61,412 patients are included in the meta-analysis. Overall, compared with the placebo group, GLP-1RA treatment could not significantly decrease heart failure hospitalization in patients with a history of heart failure (hazard ratio [HR], 1.07; 95% CI, 0.91 to 1.25; P = 0.422). Six-minute walking test distances (WMD, 19.08 m; 95% CI, 4.81 to 33.36; P = 0.01), E-wave (SMD, -0.40; 95% CI, -0.60 to -0.20; P < 0.001), early diastolic to late diastolic velocities ratio (WMD, -0.10; 95% CI, -0.18 to -0.02; P = 0.01), mitral inflow E velocity to tissue Doppler e' ratio (WMD, -0.97; 95% CI, -1.54 to -0.41; P < 0.001), and E-wave deceleration time (WMD, -9.96 milliseconds; 95% CI, -18.52 to -1.41; P = 0.02) increased significantly after administration of GLP-1RAs. However, GLP-1RAs do not significantly influence N-terminal pro-B-type natriuretic peptide levels (WMD, -20.02 pg/mL; 95% CI, -53.12 to 13.08; P = 0.24), Minnesota Living with Heart Failure Questionnaire quality of life scores (WMD, -1.08; 95% CI, -3.99 to 1.84; P = 0.47), or left ventricular ejection fractions (WMD, -0.37%; 95% CI, -1.19 to 0.46; P = 0.38).

IMPLICATIONS

GLP-1RAs did not reduce heart failure readmissions in patients with a history of heart failure and elevated N-terminal pro-B-type natriuretic peptide levels. Thus, the prognosis of heart failure was not improved, although GLP-1RAs did significantly improve left ventricular diastolic function in patients. PROSPERO identifier: CRD42021226231.

Glucose Uptake by Skeletal Muscle within the Contexts of Type 2 Diabetes and Exercise: An Integrated Approach

Type 2 diabetes continues to negatively impact the health of millions. The inability to respond to insulin to clear blood glucose (insulin resistance) is a key pathogenic driver of the disease. Skeletal muscle is the primary tissue for maintaining glucose homeostasis through glucose uptake via insulin-dependent and -independent mechanisms. Skeletal muscle is also responsive to exercise-meditated glucose transport, and as such, exercise is a cornerstone for glucose management in people with type 2 diabetes. Skeletal muscle glucose uptake requires a concert of events. First, the glucose-rich blood must be transported to the skeletal muscle. Next, the glucose must traverse the endothelium, extracellular matrix, and skeletal muscle membrane. Lastly, intracellular metabolic processes must be activated to maintain the diffusion gradient to facilitate glucose transport into the cell. This review aims to examine the physiology at each of these steps in healthy individuals, analyze the dysregulation affecting these pathways associated with type 2 diabetes, and describe the mechanisms by which exercise acts to increase glucose uptake.

Research Progress on the Cardiovascular Protective Effect of Glucagon-Like Peptide-1 Receptor Agonists

The risk of cardiovascular diseases is closely related to diabetes. Macrovascular disease is the main cause of death and disability in patients with type 2 diabetes. In recent years, the glucagon-like peptide-1 receptor agonist (GLP-1RA), a new type of hypoglycemic drug, has been shown to regulate blood sugar levels, improve myocardial ischemia, regulate lipid metabolism, improve endothelial function, and exert a protective role in the cardiovascular system. This study reviewed the protective effects of GLP-1RA on the cardiovascular system.

Diabetic cardiomyopathy: Clinical phenotype and practice

Diabetic cardiomyopathy (DCM) is a pathophysiological condition of cardiac structure and function changes in diabetic patients without coronary artery disease, hypertension, and other types of heart diseases. DCM is not uncommon in people with diabetes, which increases the risk of heart failure. However, the treatment is scarce, and the prognosis is poor. Since 1972, one clinical study after another on DCM has been conducted. However, the complex phenotype of DCM still has not been fully revealed. This dilemma hinders the pace of understanding the essence of DCM and makes it difficult to carry out penetrating clinical or basic research. This review summarizes the literature on DCM over the last 40 years and discusses the overall perspective of DCM, phase of progression, potential clinical indicators, diagnostic and screening criteria, and related randomized controlled trials to understand DCM better.

Association of Glucagon-like Peptide 1 Analogs and Agonists Administered for Obesity with Weight Loss and Adverse Events: A Systematic Review and Network Meta-analysis

BACKGROUND

Comparative effectiveness of 7 glucagon-like peptide 1 (GLP-1) agents on weight loss (WL) in obesity remains unknown.

METHODS

We performed a systematic review, network meta-analysis (NMA) utilizing the following data sources: MEDLINE, EMBASE, Scopus, Cochrane Central and clinical trial registries, from inception to March 2, 2021. The prespecified criteria for study inclusion were randomized clinical trials (RCTs) of ≥12 weeks' duration. The data appraisal and extraction were performed by two investigators independently, using the published reports. The main outcomes and statistical methods were weight loss over placebo (WLOP) and adverse events (AEs) among GLP-1 agents using random-effects NMA (frequentist approach); relative ranking using surface under the cumulative ranking (SUCRA) method and certainty of evidence using grading of recommendations, assessment, development and evaluations (GRADE).

FINDINGS

64 RCTs (from 2004 to 2021) included 27018 patients (median of age, 55.1 years old; 57.4% women; baseline weight 94.8kg and BMI 33.0kg/m²; trial duration 26 weeks). Direct meta-analysis showed significant WLOP with: -1.44kg (95% CI, -2.14 to -0.74) with dulaglutide ≥1.5 mg; -1.82kg (-2.42 to -1.23) with exenatide immediate release (IR); -2.20kg (-4.31 to -0.08) with exenatide extended release (ER); -3.20kg (-6.53 to 0.15) with efpeglenatide; -2.72kg (-3.35 to -2.09) with liraglutide ≤1.8mg; -4.49kg (-5.26 to -3.72) with liraglutide >1.8mg; -0.62kg (-1.22 to -0.02) with lixisenatide; -4.33kg (-5.71 to -3.00) with semaglutide SQ <2.4mg; -9.88kg (-13.17 to -6.59) with semaglutide SQ 2.4mg; -2.73kg (-4.81 to -0.65) with semaglutide oral; and -1.71kg (-2.64 to -0.78) with taspoglutide. Highest WLOP were with semaglutide SQ 2.4mg and <2.4mg, and liraglutide >1.8mg (SUCRAs 100, 86.1, 82.8 respectively). Highest SUCRAs for discontinuation due to AEs were with taspoglutide and liraglutide >1.8mg. Risk of bias was high or unclear for random sequence generation (29.7%), allocation concealment (26.6%), and incomplete outcome data (26.6%). Heterogeneity (I² >50%) in WL and AEs reflected magnitude, not direction of effect.

Effect of glycemic control on markers of subclinical atherosclerosis in patients with type 2 diabetes mellitus: A review

Cardiovascular disease is the predominant cause of death in type 2 diabetes mellitus (T2DM). Evidence suggests a strong association between duration and degree of hyperglycemia and vascular disease. However, large trials failed to show cardiovascular benefit after intensive glycemic control, especially in patients with longer diabetes duration. Atherosclerosis is a chronic and progressive disease, with a long asymptomatic phase. Subclinical atherosclerosis, which is impaired in T2DM, includes impaired vasodilation, increased coronary artery calcification (CAC), carotid intima media thickness, arterial stiffness, and reduced arterial elasticity. Each of these alterations is represented by a marker of subclinical atherosclerosis, offering a cost-effective alternative compared to classic cardiac imaging. Their additional use on top of traditional risk assessment strengthens the predictive risk for developing coronary artery disease (CAD). We, herein, review the existing literature on the effect of glycemic control on each of these markers separately. Effective glycemic control, especially in earlier stages of the disease, attenuates progression of structural markers like intima-media thickness and CAC. Functional markers are improved after use of newer anti-diabetic agents, such as incretin-based treatments or sodium-glucose co-transporter-2 inhibitors, especially in T2DM patients with shorter disease duration. Larger prospective trials are needed to enhance causal inferences of glycemic control on clinical endpoints of CAD.

Role of newer antidiabetic drugs on cardiovascular prevention and heart failure

Beyond glucemic control there are other important goals when it comes to providing integral care to patients with diabetes mellitus. A bibliographic review was made in order to identify the role played by new antidiabetic drugs in cardiovascular prevention and heart failure. The use of SLGT2i and GLP1a leads to a significant decrease in cardiovascular events, with no difference between the two, except when it comes to hospitalizations for heart failure, where the superiority of the last ones (especially dapaglifozin and empaglifozin) is evident. The current evidence regarding the effect of dpp-4i is diverse, although an increased risk of hospitalizations for heart failure is observed with the use of some drugs of this class (saxagliptin).

Exendin-4 Protects Against Myocardial Ischemia-Reperfusion Injury by Upregulation of SIRT1 and SIRT3 and Activation of AMPK

This study evaluated if the cardioprotective effect of Exendin-4 against ischemia/reperfusion (I/R) injury in male rats involves modulation of AMPK and sirtuins. Adult male rats were divided into sham, sham + Exendin-4, I/R, I/R + Exendin-4, and I/R + Exendin-4 + EX-527, a sirt1 inhibitor. Exendin-4 reduced infarct size and preserved the function and structure of the left ventricles (LV) of I/R rats. It also inhibited oxidative stress and apoptosis and upregulated MnSOD and Bcl-2 in their infarcted myocardium. With no effect on SIRTs 2/6/7, Exendin-4 activated and upregulated mRNA and protein levels of SIRT1, increased levels of SIRT3 protein, activated AMPK, and reduced the acetylation of p53 and PGC-1α as well as the phosphorylation of FOXO-1. EX-527 completely abolished all beneficial effects of Exendin-4 in I/R-induced rats. In conclusion, Exendin-4 cardioprotective effect against I/R involves activation of SIRT1 and SIRT3. Graphical Abstract Exendin-4 could scavenge free radical directly, upregulate p53, and through upregulation of SIRT1 and stimulating SIRT1 nuclear accumulation. In addition, Exendin-4 also upregulates SIRT3 which plays an essential role in the upregulation of antioxidants, inhibition of reactive oxygen species (ROS) generation, and prevention of mitochondria damage. Accordingly, SIRT1 induces the deacetylation of PGC-1α and p53 and is able to bind p-FOXO-1. This results in inhibition of cardiomyocyte apoptosis through increasing Bcl-2 levels, activity, and levels of MnSOD; decreasing expression of Bax; decreasing cytochrome C release; and improving mitochondria biogenesis through upregulation of Mfn-2.

New antidiabetic therapy and HFpEF: light at the end of tunnel?

New antidiabetic therapy that includes sodium-glucose co-transporter 2 (SGLT2) inhibitors, glucagon-like peptide-1 receptor (GLP-1R) agonists, and dipeptidyl peptidase 4 (DPP-4) inhibitors showed significant benefit on cardiovascular outcomes in patients with and without type 2 diabetes mellitus, and this was particularly confirmed for SGLT2 inhibitors in subjects with heart failure (HF) with reduced ejection fraction (HFrEF). Their role on patients with HF with preserved ejection fraction (HFpEF) is still not elucidated, but encouraging results coming from the clinical studies indicate their beneficial role. The role of GLP-1R agonists and particularly DPP-4 inhibitors is less clear and debatable. Findings from the meta-analyses are sending positive message about the use of GLP-1R agonists in HFrEF therapy and revealed the improvement of left ventricular (LV) diastolic function in HFpEF. Nevertheless, the relevant medical societies still consider their effect as neutral or insufficiently investigated in HF patients. The impact of DPP-4 inhibitors in HF is the most controversial due to conflicting data that range from negative impact and increased risk of hospitalization due to HF, throughout neutral effect, to beneficial influence on LV diastolic dysfunction. However, this is a very heterogeneous group of medications and some professional societies made clear discrepancy between saxagliptin that might increase risk of HF hospitalization and those DPP-4 inhibitors that have no effect on hospitalization. The aim of this review is to summarize current clinical evidence about the effect of new antidiabetic medications on LV diastolic function and their potential benefits in HFpEF patients.

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

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

Exenatide improves cardiovascular risk factors in obese patients with type 2 diabetes mellitus: a prospective study

Background/aim

The aim of this study was to evaluate the effects of a 6-month treatment regimen with exenatide on the lipid profile, high-sensitivity C-reactive protein (hsCRP), carotid intima media thickness (CIMT), visceral adiposity, and nonalcoholic fatty liver disease (NAFLD), all of which are important cardiovascular risk factors.

Materials and methods

This study included 45 obese patients with type 2 diabetes mellitus (T2DM). Baseline clinical findings, laboratory parameters, and ultrasonography findings were recorded. An exenatide recipe was given twice daily to the patients and, after 6 months of therapy, the same variables were compared. The compared parameters were lipid profiles, hsCRP, aspartat aminotransferase, alanine aminotransferase, gamma-glutamyl transferase, liver craniocaudal diameter, visceral fat volume, subcutaneous fat thickness, and CIMT. Liver diameter, visceral fat volume, subcutaneous fat thickness, and CIMT were measured by ultrasonography.

Results

After therapy, statistically significant improvements were achieved in lipid profile, hsCRP, liver enzymes, body mass index, and waist and hip circumferences. Also, statistically significant decreases were obtained in liver craniocaudal diameter, subcutaneous fat thickness, visceral fat volume, and CIMT. The reduction of CIMT and liver diameter were not correlated with BMI and HbA_1c reduction.

Conclusion

This study showed improvement in lipid profile and hsCRP levels with exenatide treatment. We also showed decrease in both visceral fat volume and subcutaneous fat thickness. We demonstrated significant decrease in liver enzymes with significant decrease in liver diameter. These findings support the use of exenatide in patients with NAFLD and T2DM. Additionally, this study showed that exenatide treatment given twice daily reduces CIMT in obese T2DM patients.

Effects of liraglutide on diastolic function parameters in patients with type 2 diabetes and coronary artery disease: a randomized crossover study

Background

Diastolic dysfunction is highly prevalent in patients with type 2 diabetes mellitus (T2DM) and is associated with overweight, glucose dysregulation and coronary artery disease (CAD). The GLP-1 receptor agonist, liraglutide, has shown to induce weight loss and improve metabolic factors, thus modulating factors associated with diastolic dysfunction. We have previously reported the effects of liraglutide on systolic function, and in this current study we explore the effects of liraglutide on diastolic function parameters in patients with stable CAD, preserved left ventricular ejection fraction (LVEF), and newly diagnosed T2DM.

Methods

Thirty subjects were randomized to liraglutide or placebo intervention for 12 + 12-weeks in this double-blind cross-over study. 2D-echocardiography using tissue velocity imaging was used for assessment of diastolic function parameters. Early diastolic filling velocity (E), late atrial filling velocity (A), E-wave deceleration time (EDT) and E/A ratio was assessed from the pulse wave (PW)-Doppler velocity recording of the mitral inflow. Peak early diastolic annular velocities (e′) was measured from color tissue doppler images.

Results

Liraglutide, when compared to placebo, induced a significant reduction in average e′ and lateral e′ velocities (– 0.57 cm/s [– 1.05 to − 0.08] and –0.74 cm/s [–1.32 to –0.15], respectively). Adjusted for the concomitant increase in HR (+ 6.16 bpm [0.79 to 11.54], the changes were not significant. No significant changes in other diastolic function parameters were observed.

Conclusions

Liraglutide therapy did not improve any diastolic function parameters in subjects with T2DM, CAD, and preserved LVEF. Instead, a deterioration in e’ was observed, which was associated to an increase in heart rate induced by liraglutide therapy.

Trial registration Clinical Trial Registration: http://www.clinicaltrials.gov (unique identifier: NCT01595789) (first submitted May 8, 2012)

Diastolic Cardiac Function Improvement by Liraglutide Is Mainly Body Weight Reduction Dependent but Independently Contributes to B-Type Natriuretic Peptide Reduction in Patients with Type 2 Diabetes with Preserved Ejection Fraction

OBJECTIVES

A single-arm prospective study was conducted among Japanese patients with type 2 diabetes having preserved ejection fraction. The aim was to investigate (1) whether liraglutide therapy could improve B-type natriuretic peptide (BNP) levels and diastolic cardiac function assessed by the E-wave to E' ratio (E/E') using transthoracic echocardiography (TTE), and (2) whether E/E' contributed to BNP improvement independent of bodyweight reduction (UMIN000005565).

METHODS

Patients with type 2 diabetes and left ventricular ejection fraction (LVEF) ≥ 40% without heart failure symptoms were enrolled, and daily injection with liraglutide (0.9 mg) was introduced. Cardiac functions were assessed by TTE before and after 26 weeks of liraglutide treatment. Diastolic cardiac function was defined as septal E/E' ≥ 13.0.

RESULTS

Thirty-one patients were analyzed. BNP and E/E' improved, with BNP levels declining from 36.8 ± 30.5 pg/mL to 26.3 ± 25.9 pg/mL (p = 0.0014) and E/E' dropping from 12.7 ± 4.7 to 11.0 ± 3.3 (p = 0.0376). The LVEF showed no significant changes. E/E' improved only in patients with E/E' ≥ 13.0. Favorable changes in E/E' were canceled when adjusted for body mass index (BMI). Multivariate linear regression analysis revealed that the left ventricular diastolic diameter and ∆E/E'/∆BMI contributed to ∆BNP/baseline BNP (p = 0.0075, R ² = 0.49264).

CONCLUSIONS

Liraglutide had favorable effects on BNP and E/E' but not on LVEF. E/E' improvement was only seen in patients with diastolic cardiac function. Body weight reduction affected the change of E/E'. The BMI-adjusted E/E' significantly contributed to the relative change of BNP. GLP-1 analog treatment could be considered a therapeutic option against diabetic diastolic cardiac dysfunction regardless of body weight. This trial is registered with the University Hospital Medical Information Network in Japan, with clinical trial registration number: UMIN000005565.

The Impact of Antidiabetic Therapies on Diastolic Dysfunction and Diabetic Cardiomyopathy

Diabetic cardiomyopathy is more prevalent in people with type 2 diabetes mellitus (T2DM) than previously recognized, while often being characterized by diastolic dysfunction in the absence of systolic dysfunction. This likely contributes to why heart failure with preserved ejection fraction is enriched in people with T2DM vs. heart failure with reduced ejection fraction. Due to revised mandates from major health regulatory agencies, all therapies being developed for the treatment of T2DM must now undergo rigorous assessment of their cardiovascular risk profiles prior to approval. As such, we now have data from tens of thousands of subjects with T2DM demonstrating the impact of major therapies including the sodium-glucose co-transporter 2 (SGLT2) inhibitors, glucagon-like peptide-1 receptor (GLP-1R) agonists, and dipeptidyl peptidase 4 (DPP-4) inhibitors on cardiovascular outcomes. Evidence to date suggests that both SGLT2 inhibitors and GLP-1R agonists improve cardiovascular outcomes, whereas DPP-4 inhibitors appear to be cardiovascular neutral, though evidence is lacking to determine the overall utility of these therapies on diastolic dysfunction or diabetic cardiomyopathy in subjects with T2DM. We herein will review the overall impact SLGT2 inhibitors, GLP-1R agonists, and DPP-4 inhibitors have on major parameters of diastolic function, while also highlighting the potential mechanisms of action responsible. A more complete understanding of how these therapies influence diastolic dysfunction will undoubtedly play a major role in how we manage cardiovascular disease in subjects with T2DM.

Mechanistic Causes of Reduced Cardiorespiratory Fitness in Type 2 Diabetes

Type 2 diabetes (T2D) has been rising in prevalence in the United States and worldwide over the past few decades and contributes to significant morbidity and premature mortality, primarily due to cardiovascular disease (CVD). Cardiorespiratory fitness (CRF) is a modifiable cardiovascular (CV) risk factor in the general population and in people with T2D. Young people and adults with T2D have reduced CRF when compared with their peers without T2D who are similarly active and of similar body mass index. Furthermore, the impairment in CRF conferred by T2D is greater in women than in men. Various factors may contribute to this abnormality in people with T2D, including insulin resistance and mitochondrial, vascular, and cardiac dysfunction. As proof of concept that understanding the mediators of impaired CRF in T2D can inform intervention, we previously demonstrated that an insulin sensitizer improved CRF in adults with T2D. This review focuses on how contributing factors influence CRF and why they may be compromised in T2D. Functional exercise capacity is a measure of interrelated systems biology; as such, the contribution of derangement in each of these factors to T2D-mediated impairment in CRF is complex and varied. Therefore, successful approaches to improve CRF in T2D should be multifaceted and individually designed. The current status of this research and future directions are outlined.

Exendin-4 protects the hearts of rats from ischaemia/reperfusion injury by boosting antioxidant levels and inhibition of JNK/p66 Shc/NADPH axis

Exendin-4, a glucagon-like peptide-1 receptor agonist, was shown to protect against cardiac ischaemia/reperfusion (I/R) injury by suppressing oxidative stress. p⁶⁶ Shc, a pro-oxidant and an apoptotic protein, is activated in the infarcted left ventricles (LVs) after induction of I/R. This study investigated if the cardiac protective effect of Exendin-4 against I/R injury in rats involves inhibition of p⁶⁶ Shc and to determine the underlying mechanisms behind this. Adult male rats (n = 12/group) were divided into four groups as a sham, a sham + Exendin-4, an I/R, and an I/R + Exendin-4. Exendin-4 was administered to rats 7 days before the induction of I/R. Ischaemia was induced by ligating the left anterior descending (LAD) coronary artery for 40 minutes followed by reperfusion for 10 minutes. The infarct myocardium was used for further analysis. Exendin-4 significantly reduced infarct area (by 62%), preserved LV function and lowered serum levels of LDH and CK-MB in I/R-induced rats. Also, it significantly reduced LV levels of ROS and MDA and protein levels of cytochrome-c and cleaved caspase-3 but significantly increased levels of glutathione (GSH) and manganese superoxide dismutase (MnSOD) in LVs of I/R rats indicating antioxidant and anti-apoptotic effects. Furthermore, it inhibited JNK and p⁶⁶ Shc activation and downregulated protein levels of p⁶⁶ Shc and NADPH oxidase with no effect on protein levels/activity of p53 and PKCβII. Of note, Exendin-4 also increased GSH and MnSOD in LVs of control rats. In conclusion, Exendin-4 cardioprotective effect in I/R hearts is mediated mainly by antioxidant effect and inhibition of JNK/P⁶⁶ Shc/NADPH oxidase.

Effects of oral antidiabetic drugs and glucagon-like peptide-1 receptor agonists on left ventricular diastolic function in patients with type 2 diabetes mellitus: a systematic review and network meta-analysis

The present study aimed to compare the effects of oral antidiabetic drugs (OADs) and glucagon-like peptide-1 receptor agonists (GLP-1RAs) on left ventricular diastolic function in patients with type 2 diabetes mellitus using a network meta-analysis of randomized controlled trials (RCTs). Literature searches were conducted on Medline, the Cochrane Controlled Trials Registry, and ClinicalTrials.gov . RCTs that assessed the effects on left ventricular diastolic function of OADs and GLP-1RAs in patients with type 2 diabetes were included. The outcome was the value (E/e') obtained by dividing peak early diastolic transmitral flow velocity (E) by the mitral annular early diastolic velocity (e'). Standardized mean differences (SMD) and 95% confidence intervals (CIs) were calculated from a random-effects network meta-analysis. Eight RCTs (592 patients) identified in a literature search met the eligibility criteria for this study and were included in the network meta-analysis. Compared with placebo, liraglutide was the only drug that caused a significant improvement in left ventricular diastolic function (SMD, - 0.65; 95% CI, - 1.23 to - 0.08). In addition, when the effects on left ventricular diastolic function were evaluated across drugs, liraglutide alone caused a significant improvement in left ventricular diastolic function compared with OADs (sitagliptin, linagliptin, pioglitazone, rosiglitazone, voglibose, and glimepiride). From the perspective of preventing the onset of heart failure, the administration of liraglutide for type 2 diabetes is promising.

Therapy for heart failure with preserved ejection fraction: current status, unique challenges, and future directions

Heart failure (HF) with preserved ejection fraction (HFpEF) is the most common form of HF. Among elderly women, HFpEF comprises more than 80% of incident HF cases. Adverse outcomes-exercise intolerance, poor quality of life, frequent hospitalizations, and reduced survival-approach those of classic HF with reduced EF (HFrEF). However, despite its importance, our understanding of the pathophysiology of HFpEF is incomplete, and despite intensive efforts, optimal therapy remains uncertain, as most trials to date have been negative. This is in stark contrast to management of HFrEF, where dozens of positive trials have established a broad array of effective, guidelines-based therapies that definitively improve a range of clinically meaningful outcomes. In addition to providing an overview of current management status, we examine evolving data that may help explain this paradox, overcome past challenges, provide a roadmap for future success, and that underpin a wave of new trials that will test novel approaches based on these insights.

Sodium-glucose co-transporter inhibitors: Medications that mimic fasting for cardiovascular prevention

Recent evidence that some diabetes drugs can prevent cardiovascular disease (CVD) has profoundly modified the treatment approach to type 2 diabetes mellitus. Sodium-glucose co-transporter-2 (SGLT2) inhibitors and almost all glucagon-like peptide-1 receptor agonists (GLP-1RAs) have been shown, beyond their effect on glucose control, to lead to a significant decrease in the cardiovascular burden of diabetes. Although these results are well known, the mechanisms of action by which they prevent cardiovascular events are still poorly understood. Both GLP-1RAs and SGLT2 inhibitors promote weight loss, although through different mechanisms. SGLT2 inhibitors promote glycosuria, leading to significant caloric deficit and weight loss. Similarly, GLP-1RAs, probably through an anorexic effect on certain brain areas, inhibit calorie intake, with ensuing weight loss. Although it features less prominently in current treatment pathways, pioglitazone has also demonstrated cardiovascular benefits. Pioglitazone profoundly modifies several mechanisms and risk factors responsible for CVD; however, these mechanisms certainly do not include weight loss. Obesity, and consequent insulin resistance, are well known risk factors for CVD, and it would appear logical to attribute the positive cardiovascular effects of these two classes of drugs to weight loss. The direct metabolic effects of these two classes, however, are profoundly different. The present review proposes a unifying hypothesis to explain the reduction in CVD through three different mechanisms of curbing free fatty acid excess, all leading to the common mechanism of cellular caloric restriction. If this hypothesis is correct, the excellent results obtained with SGLT2 inhibitors could be attributed to their close simulation of fasting.

Gut microbiota regulates cardiac ischemic tolerance and aortic stiffness in obesity

The gut microbiota has emerged as an important regulator of host physiology, with recent data suggesting a role in modulating cardiovascular health. The present study determined if gut microbial signatures could transfer cardiovascular risk phenotypes between lean and obese mice using cecal microbiota transplantation (CMT). Pooled cecal contents collected from obese leptin-deficient (Ob) mice or C57Bl/6j control (Con) mice were transplanted by oral gavage into cohorts of recipient Ob and Con mice maintained on identical low-fat diets for 8 wk (n = 9-11/group). Cardiovascular pathology was assessed as the degree of arterial stiffness (aortic pulse wave velocity) and myocardial infarct size following a 45/120 min ex vivo global cardiac ischemia-reperfusion protocol. Gut microbiota was characterized by 16S rDNA sequencing, along with measures of intestinal barrier function and cecal short-chain fatty acid (SCFA) composition. Following CMT, the gut microbiota of recipient mice was altered to resemble that of the donors. Ob CMT to Con mice increased arterial stiffness, left ventricular (LV) mass, and myocardial infarct size, which were associated with greater gut permeability and reduced cecal SCFA concentrations. Conversely, Con CMT to Ob mice increased cecal SCFA, reduced LV mass, and attenuated myocardial infarct size, with no effects on gut permeability or arterial stiffness. Collectively, these data demonstrate that obesity-related changes in the gut microbiota, independent of dietary manipulation, regulate hallmark measures of cardiovascular pathology in mice and highlight the potential of microbiota-targeted therapeutics for reducing cardiovascular pathology and risk in obesity.NEW & NOTEWORTHY These data are the first to demonstrate that cecal microbiota transplantation (CMT) can alter cardiovascular pathology in lean and obese mice independent from alterations in dietary intake. Myocardial infarct size was reduced in obese mice receiving lean CMT and worsened in lean mice receiving obese CMT. Lean mice receiving obese CMT also displayed increased aortic stiffness. These changes were accompanied by alterations in short-chain fatty acids and gut permeability.

Sitagliptin improves diastolic cardiac function but not cardiorespiratory fitness in adults with type 2 diabetes

BACKGROUND

People with type 2 diabetes mellitus (T2D) have preclinical cardiac and vascular dysfunction associated with low cardiorespiratory fitness (CRF). This is especially concerning because CRF is a powerful predictor of cardiovascular mortality, a primary issue in T2D management. Glucagon-like pepetide-1 (GLP-1) augments cardiovascular function and our previous data in rodents demonstrate that potentiating the GLP-1 signal with a dipeptidyl peptidase-4 (DPP4) inhibitor augments CRF. Lacking are pharmacological treatments which can target T2D-specific physiological barriers to exercise to potentially permit adaptations necessary to improve CRF and thereby health outcomes in people with T2D. We therefore hypothesized that administration of a DPP4-inhibitor (sitagliptin) would improve CRF in adults with T2D.

METHODS AND RESULTS

Thirty-eight participants (64 ± 1 years; mean ± SE) with T2D were randomized in a double-blinded study to receive 100 mg/day sitagliptin, 2 mg/day glimepiride, or placebo for 3 months after baseline measurements. Fasting glucose decreased with both glimepiride and sitagliptin compared with placebo (P = 0.002). CRF did not change in any group (Placebo: Pre: 15.4 ± 0.9 vs. Post: 16.1 ± 1.1 ml/kg/min vs. Glimepiride: 18.5 ± 1.0 vs. 17.7 ± 1.2 ml/kg/min vs. Sitagliptin: 19.1 ± 1.2 vs. 18.3 ± 1.1 ml/kg/min; P = 0.3). Sitagliptin improved measures of cardiac diastolic function, however, measures of vascular function did not change with any treatment.

CONCLUSIONS

Three months of sitagliptin improved diastolic cardiac function, however, CRF did not change. These data suggest that targeting the physiological contributors to CRF with sitagliptin alone is not an adequate strategy to improve CRF in people with T2D.

CLINICAL TRIALS REGISTRATION

www.clinicaltrials.gov NCT01951339.

Exenatide once-weekly improves metabolic parameters, endothelial dysfunction and carotid intima-media thickness in patients with type-2 diabetes: An 8-month prospective study

AIM

To evaluate the effect of exenatide long acting release (LAR) on carotid intima-media thickness (IMT) and endothelial function in patients with type 2 diabetes mellitus.

METHODS

Sixty subjects with type 2 diabetes mellitus were treated with exenatide LAR as add-on to stable doses of metformin for 8 months in an open label study. Anthropometric variables, lipid profile and glycemic parameters were assessed by routine analysis. Carotid IMT by Doppler ultrasound and endothelial function by flow-mediated dilation of the brachial artery were also assessed.

RESULTS

Exenatide significantly improved fasting glycaemia (from 8.8 ± 2.8 to 7.3 ± 2.2 mmol/L, p < 0.0001), HbA1c (from 8.0 ± 0.4 to 6.9 ± 1.1%, p < 0.0001), body mass index (from 33 ± 9 to 31 ± 6 kg/m², p = 0.0348) and waist circumference (from 109 ± 13 to 106 ± 13 cm, p = 0.0105). There was a significant improvement of the lipid profile, except in triglyceride level where no changes were observed. Carotid IMT and flow-mediated dilation were also improved (from 0.98 ± 0.14 to 0.87 ± 0.15 mm and from 5.8 ± 1.3 to 6.8 ± 1.7%, respectively; p < 0.0001 for both).

CONCLUSIONS

Treatment with exenatide LAR led to improved cardio-metabolic parameters, including carotid IMT and flow-mediated dilation, independently of glucometabolic control. These results may help to explain, at least in part, the cardiovascular safety of exenatide LAR, as recently reported in cardiovascular outcome trials.

Physical exercise and non-insulin glucose-lowering therapies in the management of Type 2 diabetes mellitus: a clinical review

In the UK the National Institute of Health and Care Excellence (NICE) advocates intensive lifestyle programmes that attain the levels of daily physical activity set out by the Chief Medical Officer as a first-line strategy for improving the health of people at risk of developing diabetes or reducing the risk of development of Type 2 diabetes. For people with Type 2 diabetes, lifestyle measures complement pharmacological treatments that include both oral and injectable therapies. In line with this, NICE guidelines also support intensification of efforts to improve patient lifestyle along with these glucose-lowering therapies. There is a paucity of evidence, however, in the available published literature examining the association between glucose-lowering therapies and exercise metabolism. In the present review we explore the current knowledge with regard to the potential interactions of oral and non-insulin injectable therapies with physical activity in people at risk of, or who have, Type 2 diabetes, and present evidence that may inform healthcare professionals of the need to monitor patients more closely in their adaptation to both pharmacological therapy and physical activity.

Exenatide Protects Against Cardiac Dysfunction by Attenuating Oxidative Stress in the Diabetic Mouse Heart

Cardiovascular disease is the major cause of death in patients with diabetes. Current treatment strategies for diabetes rely on lifestyle changes and glucose control to prevent angiopathy and organ failure. Exenatide, a glucagon-like peptide-1 (GLP-1) receptor agonist, is used as an add-on therapy to insulin treatment. Exenatide also has multiple beneficial effects in addition to its hypoglycemic effects, such as preventing hepatic steatosis and protecting against cardiac injury from doxorubicin-induced cardiotoxicity or ischemic reperfusion. However, the mechanisms underlying the cardioprotective effects of exenatide in diabetes have not been fully clarified. To address this issue, we investigated the cardioprotective effects of exenatide in type 1 and type 2 diabetic mice. We found that exenatide simultaneously attenuated reactive oxidative species (ROS) production through increases in the antioxidant enzymes manganese dependent superoxide dismutase (MnSOD) and catalase. Moreover, exenatide decreased tumor protein P53 (p53) expression and prevented cell apoptosis in H9c2 cells. The presence of the catalase inhibitor 3-AT attenuated the effects of exenatide. Overall, the results strongly indicate that exenatide treatment may be protective against the development of diabetic cardiomyopathy.

Effects of glucose-lowering agents on cardiorespiratory fitness

Exercise therapy is essential for the management of type 2 diabetes (T2D). However, patients with T2D show lower physical activity and reduced cardiorespiratory fitness than healthy individuals. It would be ideal for clinicians to co-prescribe glucose-lowering agents that improve cardiorespiratory fitness or exercise capacity in conjunction with exercise therapy. Metformin does not improve cardiorespiratory fitness and may attenuate any beneficial effect of exercise in patients with T2D. In contrast, thiazolidinediones appear to improve cardiorespiratory fitness in patients with T2D. Although evidence is limited, sodium-glucose cotransporter 2 (SGLT2) inhibitors may improve cardiorespiratory fitness in patients with heart failure, and the effect of glucagon-like peptide-1 (GLP-1) receptor agonists on cardiorespiratory fitness is controversial. Recent clinical trials have shown that both SGLT2 inhibitors and GLP-1 receptor agonists exert a favorable effect on cardiovascular disease. It becomes more important to choose drugs that have beneficial effects on the cardiovascular system beyond glucose-lowering effects. Further studies are warranted to determine an ideal glucose-lowering agent combined with exercise therapy for the treatment of T2D.

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

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

Glucagon-like peptide-1 receptor antagonism impairs basal exercise capacity and vascular adaptation to aerobic exercise training in rats

Cardiorespiratory fitness (CRF) inversely predicts cardiovascular (CV) mortality and CRF is impaired in people with type 2 diabetes (T2D). Aerobic exercise training (ET) improves CRF and is associated with decreased risk of premature death in healthy and diseased populations. Understanding the mechanisms contributing to ET adaptation may identify targets for reducing CV mortality of relevance to people with T2D. The antihyperglycemic hormone glucagon-like peptide-1 (GLP-1) influences many of the same pathways as exercise and may contribute to CV adaptation to ET. We hypothesized that GLP-1 is necessary for adaptation to ET. Twelve-week-old male Wistar rats were randomized (n = 8-12/group) to receive PBS or GLP-1 receptor antagonist (exendin 9-39 (Ex(9-39)) via osmotic pump for 4 weeks ± ET. CRF was greater with ET (P < 0.01). Ex(9-39) treatment blunted CRF in both sedentary and ET rats (P < 0.001). Ex(9-39) attenuated acetylcholine-mediated vasodilation, while this response was maintained with Ex(9-39)+ET (P = 0.04). Aortic stiffness was greater with Ex(9-39) (P = 0.057) and was made worse when Ex(9-39) was combined with ET (P = 0.004). Ex vivo aortic vasoconstriction with potassium and phenylephrine was lower with Ex(9-39) (P < 0.0001). Carotid strain improved with PBS + ET but did not change in the Ex(9-39) rats with ET (P < 0.0001). Left ventricular mitochondrial respiration was elevated with Ex(9-39) (P < 0.02). GLP-1 receptor antagonism impairs CRF with and without ET, attenuates the vascular adaptation to ET, and elevates cardiac mitochondrial respiration. These data suggest that GLP-1 is integral to the adaptive vascular response to ET.

Effects of 6-month treatment with the glucagon like peptide-1 analogue liraglutide on arterial stiffness, left ventricular myocardial deformation and oxidative stress in subjects with newly diagnosed type 2 diabetes

Background

Incretin-based therapies are used in the treatment of type 2 diabetes mellitus (T2DM) and obesity. We investigated the changes in arterial stiffness and left ventricular (LV) myocardial deformation after 6-month treatment with the GLP-1 analogue liraglutide in subjects with newly diagnosed T2DM.

Methods

We randomized 60 patients with newly diagnosed and treatment-naive T2DM to receive either liraglutide (n = 30) or metformin (n = 30) for 6 months. We measured at baseline and after 6-month treatment: (a) carotid-femoral pulse wave velocity (PWV) (b) LV longitudinal strain (GLS), and strain rate (GLSR), peak twisting (pTw), peak twisting velocity (pTwVel) and peak untwisting velocity (pUtwVel) using speckle tracking echocardiography. LV untwisting was calculated as the percentage difference between peak twisting and untwisting at MVO (%dpTw–Utw_MVO), at peak (%dpTw–Utw_PEF) and end of early LV diastolic filling (%dpTw–Utw_EDF) (c) Flow mediated dilatation (FMD) of the brachial artery and percentage difference of FMD (FMD%) (d) malondialdehyde (MDA), protein carbonyls (PCs) and NT-proBNP.

Results

After 6-months treatment, subjects that received liraglutide presented with a reduced PWV (11.8 ± 2.5 vs. 10.3 ± 3.3 m/s), MDA (0.92 [0.45–2.45] vs. 0.68 [0.43–2.08] nM/L) and NT-proBNP (p < 0.05) in parallel with an increase in GLS (− 15.4 ± 3 vs. − 16.6 ± 2.7), GLSR (0.77 ± 0.2 vs. 0.89 ± 0.2), pUtwVel (− 97 ± 49 vs. − 112 ± 52°, p < 0.05), %dpTw–Utw_MVO (31 ± 10 vs. 40 ± 14), %dpTw–Utw_PEF (43 ± 19 vs. 53 ± 22) and FMD% (8.9 ± 3 vs. 13.2 ± 6, p < 0.01). There were no statistically significant differences of the measured markers in subjects that received metformin except for an improvement in FMD. In all subjects, PCs levels at baseline were negatively related to the difference of GLS (r = − 0.53) post-treatment and the difference of MDA was associated with the difference of PWV (r = 0.52) (p < 0.05 for all associations) after 6-month treatment.

Conclusions

Six-month treatment with liraglutide improves arterial stiffness, LV myocardial strain, LV twisting and untwisting and NT-proBNP by reducing oxidative stress in subjects with newly diagnosed T2DM.

ClinicalTrials.gov Identifier NCT03010683

Mechanisms of Aerobic Exercise Impairment in Diabetes: A Narrative Review

The prevalence of diabetes in the United States and globally has been rapidly increasing over the last several decades. There are now estimated to be 30.3 million people in the United States and 422 million people worldwide with diabetes. Diabetes is associated with a greatly increased risk of cardiovascular mortality, which is the leading cause of death in adults with diabetes. While exercise training is a cornerstone of diabetes treatment, people with diabetes have well-described aerobic exercise impairments that may create an additional diabetes-specific barrier to adding regular exercise to their lifestyle. Physiologic mechanisms linked to exercise impairment in diabetes include insulin resistance, cardiac abnormalities, mitochondrial function, and the ability of the body to supply oxygen. In this paper, we highlight the abnormalities of exercise in type 2 diabetes as well as potential therapeutic approaches.

Acute vitamin C improves cardiac function, not exercise capacity, in adults with type 2 diabetes

BACKGROUND

People with type 2 diabetes (T2D) have impaired exercise capacity, even in the absence of complications, which is predictive of their increased cardiovascular mortality. Cardiovascular dysfunction is one potential cause of this exercise defect. Acute infusion of vitamin C has been separately shown to improve diastolic and endothelial function in prior studies. We hypothesized that acute vitamin C infusion would improve exercise capacity and that these improvements would be associated with improved cardiovascular function.

METHODS

Adults with T2D (n = 31, 7 female, 24 male, body mass index (BMI): 31.5 ± 0.8 kg/m²) and BMI-similar healthy adults (n = 21, 11 female, 10 male, BMI: 30.4 ± 0.7 kg/m²) completed two randomly ordered visits: IV infusion of vitamin C (7.5 g) and a volume-matched saline infusion. During each visit peak oxygen uptake (VO₂peak), brachial artery flow mediated dilation (FMD), reactive hyperemia (RH; plethysmography), and cardiac echocardiography were measured. General linear mixed models were utilized to assess the differences in all study variables.

RESULTS

Acute vitamin C infusion improved diastolic function, assessed by lateral and septal E:E' (P < 0.01), but did not change RH (P = 0.92), or VO₂peak (P = 0.33) in any participants.

CONCLUSION

Acute vitamin C infusion improved diastolic function but did not change FMD, forearm reactive hyperemia, or peak exercise capacity. Future studies should further clarify the role of endothelial function as well as other possible physiological causes of exercise impairment in order to provide potential therapeutic targets.Trial registration NCT00786019. Prospectively registered May 2008.

Heart Failure with Preserved Ejection Fraction and Future Pharmacological Strategies: a Glance in the Crystal Ball

PURPOSE OF REVIEW

The current definition of heart failure is mainly based on an inappropriate measure of cardiac function, i.e., left ventricular ejection fraction (LVEF). The initial sole entity, heart failure with reduced ejection fraction (HFrEF, LVEF <40%), was complemented by the addition of heart failure with preserved ejection fraction (HFpEF, LVEF ≥50%) and most recently, heart failure with mid-range ejection fraction (HFmrEF, LVEF 40-49%). Initially, HFpEF was believed to be a purely left ventricular diastolic dysfunction. Pathophysiological concepts of HFpEF have changed considerably during the last years. In addition to intrinsic cardiac mechanisms, the heart failure pathogenesis is increasingly considered as driven by non-cardiac systemic processes including metabolic disorders, ischemic conditions, and pro-inflammatory/pro-fibrotic or immunological alterations. Presentation and pathophysiology of HFpEF is heterogeneous, and its management remains a challenge since evidence of therapeutic benefits is scarce. Up to now, there are no therapies improving survival in patients with HFpEF.

RECENT FINDINGS

Several results from clinical and preclinical interventions targeting non-cardiac mechanisms or non-pharmacological interventions including new anti-diabetic or anti-inflammatory drugs, mitochondrial-targeted anti-oxidants, anti-fibrotic strategies, microRNases incl. antagomirs, cell therapeutic options, and high-density lipoprotein-raising strategies are promising and under further investigation. This review addresses mechanisms and available data of current best clinical practice and novel approaches towards HFpEF.

Heart failure with preserved ejection fraction: current management and future strategies : Expert opinion on the behalf of the Nucleus of the "Heart Failure Working Group" of the German Society of Cardiology (DKG)

About 50% of all patients suffering from heart failure (HF) exhibit a reduced ejection fraction (EF ≤ 40%), termed HFrEF. The others may be classified into HF with midrange EF (HFmrEF 40-50%) or preserved ejection fraction (HFpEF, EF ≥ 50%). Presentation and pathophysiology of HFpEF is heterogeneous and its management remains a challenge since evidence of therapeutic benefits on outcome is scarce. Up to now, there are no therapies improving survival in patients with HFpEF. Thus, the treatment targets symptom relief, quality of life and reduction of cardiac decompensations by controlling fluid retention and managing risk factors and comorbidities. As such, renin-angiotensin-aldosterone inhibitors, diuretics, calcium channel blockers (CBB) and beta-blockers, diet and exercise recommendations are still important in HFpEF, although these interventions are not proven to reduce mortality in large randomized controlled trials. Recently, numerous new treatment targets have been identified, which are further investigated in studies using, e.g. soluble guanylate cyclase stimulators, inorganic nitrates, the angiotensin receptor neprilysin inhibitor LCZ 696, and SGLT2 inhibitors. In addition, several devices such as the CardioMEMS, interatrial septal devices (IASD), cardiac contractility modulation (CCM), renal denervation, and baroreflex activation therapy (BAT) were investigated in different forms of HFpEF populations and some of them have the potency to offer new hopes for patients suffering from HFpEF. On the basic research field side, lot of new disease-modifying strategies are under development including anti-inflammatory drugs, mitochondrial-targeted antioxidants, new anti-fibrotic and microRNA-guided interventions are under investigation and showed already promising results. This review addresses available data of current best clinical practice and management approaches based on expert experiences and summarizes novel approaches towards HFpEF.

Effect of linagliptin on pulse wave velocity in early type 2 diabetes: A randomized, double-blind, controlled 26-week trial (RELEASE)

AIMS

To evaluate the effects of the dipeptidyl peptidase-4 (DPP-4) inhibitor linagliptin on aortic pulse wave velocity (PWV) as a surrogate marker of arterial stiffness and early atherosclerosis in people with early type 2 diabetes.

METHODS

A total of 45 people with type 2 diabetes (median [interquartile range] age 63 [54-66] years, 61% men, mean ± standard deviation glycated haemoglobin [HbA1c] 6.3% ± 0.4% [45 ± 4.6 mmol/mol]), without cardiovascular disease and naïve to antidiabetic treatment, were randomized (1:1) to treatment with linagliptin 5 mg once daily or placebo for 26 weeks in a double-blind fashion. PWV was assessed at baseline, 4 and 26 weeks of treatment, and again at 30, 4 weeks after treatment. The primary endpoint was between-group difference in PWV (corrected for systolic blood pressure [SBP]) at week 26. Secondary endpoints included differences in central SBP and augmentation index (AIx).

RESULTS

Compared with placebo, 26 weeks of linagliptin decreased PWV by an average of 0.91 m/s (95% confidence interval -1.76 to -0.06; P = .035). PWV returned to baseline after 4 weeks washout. Differences in central SBP and AIx were not different between linagliptin and placebo. Linagliptin decreased HbA1c (-0.4%; P < .001), fasting plasma glucose (-0.7 mmol/L; P = .002) and triglycerides (-0.49 mmol/L; P = .019) as compared with placebo. The changes in body weight, cholesterol and high-sensitivity C-reactive protein did not differ between groups.

CONCLUSIONS

Linagliptin decreased aortic PWV in people with early-stage type 2 diabetes as compared with placebo after 26 weeks of treatment. These results suggest that linagliptin has a favourable effect on arterial stiffness.