The SGLT2 Inhibitor Dapagliflozin Significantly Improves the Peripheral Microvascular Endothelial Function in Patients with Uncontrolled Type 2 Diabetes Mellitus

Antifibrotic effects of sodium-glucose cotransporter-2 inhibitors: A comprehensive review

BACKGROUND AND AIMS

Scar tissue accumulation in organs is the underlying cause of many fibrotic diseases. Due to the extensive array of organs affected, the long-term nature of fibrotic processes and the large number of people who suffer from the negative impact of these diseases, they constitute a serious health problem for modern medicine and a huge economic burden on society. Sodium-glucose cotransporter-2 inhibitors (SGLT2is) are a relatively new class of anti-diabetic pharmaceuticals that offer additional benefits over and above their glucose-lowering properties; these medications modulate a variety of diseases, including fibrosis. Herein, we have collated and analyzed all available research on SGLT2is and their effects on organ fibrosis, together with providing a proposed explanation as to the underlying mechanisms.

METHODS

PubMed, ScienceDirect, Google Scholar and Scopus were searched spanning the period from 2012 until April 2023 to find relevant articles describing the antifibrotic effects of SGLT2is.

RESULTS

The majority of reports have shown that SGLT2is are protective against lung, liver, heart and kidney fibrosis as well as arterial stiffness. According to the results of clinical trials and animal studies, many SGLT2 inhibitors are promising candidates for the treatment of fibrosis. Recent studies have demonstrated that SGLT2is affect an array of cellular processes, including hypoxia, inflammation, oxidative stress, the renin-angiotensin system and metabolic activities, all of which have been linked to fibrosis.

CONCLUSION

Extensive evidence indicates that SGLT2is are promising treatments for fibrosis, demonstrating protective effects in various organs and influencing key cellular processes linked to fibrosis.

Dapagliflozin improves erectile dysfunction in patients with type 2 diabetes mellitus: An open-label, non-randomized pilot study

INTRODUCTION

The role of dapagliflozin on erectile dysfunction (ED), a condition widely affecting patients with type 2 diabetes mellitus (T2DM), has not yet been studied.

AIM

The aim of the study was to evaluate the effects of dapagliflozin alone or in combination with tadalafil on ED in patients with T2DM.

METHODS

This was an open-label, non-randomized pilot study involving 30 Caucasian male patients with T2DM and severe ED. They were equally divided into three groups, assigned to treatment with tadalafil 5 mg/day (Group 1), tadalafil 5 mg/day plus dapagliflozin 10 mg/day (Group 2) and dapagliflozin 10 mg/day (Group 3) for 3 months. The presence and the severity of ED were evaluated at enrolment and after treatment, by the International Index of Erectile Function 5-item (IIEF-5) questionnaire and the dynamic penile echo colour Doppler ultrasound (PCDU) examination.

RESULTS

At the end of treatment, the three groups showed a significant improvement in IIEF-5 score, by 294%, 375% and 197%, in Groups 1, 2 and 3, respectively. PCDU evaluation showed a significant increase in peak systolic velocity by 178.9%, 339% and 153%; acceleration time was significantly shortened in Group 2 (-26.2%) and was significantly lower than in Group 1 and 3 (-7.2% and -6.6%), while no significant difference was found in end-diastolic velocity after treatment. The greatest rates of improvement were observed in Group 2 for all the end points.

CONCLUSIONS

Dapagliflozin improves ED in patients with T2DM and enhances the efficacy of tadalafil. Further studies are needed to confirm our results explain the mechanism(s) by which dapagliflozin exerts its effects on ED.

The effect of SGLT2 inhibitors on the endothelium and the microcirculation: from bench to bedside and beyond

AIMS

The beneficial cardiovascular effects of sodium-glucose cotransporter 2 (SGLT2) inhibitors irrespective of the presence of diabetes mellitus are nowadays well established and they already constitute a significant pillar for the management of heart failure, irrespective of the ejection fraction. The exact underlying mechanisms accountable for these effects, however, remain largely unknown. The direct effect on endothelial function and microcirculation is one of the most well studied. The broad range of studies presented in this review aims to link all available data from the bench to bedside and highlight the existing gaps as well as the future directions in the investigations concerning the effects of SGLT2 inhibitors on the endothelium and the microcirculation.

METHODS AND RESULTS

An extensive search has been conducted using the MEDLINE/PubMed database in order to identify the relevant studies. Preclinical data suggest that SGLT2 inhibitors directly affect endothelial function independently of glucose and specifically via several interplaying molecular pathways, resulting in improved vasodilation, increased NO production, enhanced mitochondrial homeostasis, endothelial cell viability, and angiogenesis as well as attenuation of oxidative stress and inflammation. Clinical data systematically confirm this beneficial effect on the endothelium, whereas the evidence concerning the effect on the microcirculation is conflicting.

CONCLUSION

Preclinical and clinical studies indicate that SGLT2 inhibitors attenuate endothelial and microvascular dysfunction via a combination of mechanisms, which play a role in their beneficial cardiovascular effect.

Changes in Cardiovascular and Renal Biomarkers Associated with SGLT2 Inhibitors Treatment in Patients with Type 2 Diabetes Mellitus

Type 2 diabetes mellitus is a major health problem worldwide with a steadily increasing prevalence reaching epidemic proportions. The major concern is the increased morbidity and mortality due to diabetic complications. Traditional but also nontraditional risk factors have been proposed to explain the pathogenesis of type 2 diabetes mellitus and its complications. Hyperglycemia has been considered an important risk factor, and the strict glycemic control can have a positive impact on microangiopathy but not macroangiopathy and its related morbidity and mortality. Thus, the therapeutic algorithm has shifted focus from a glucose-centered approach to a strategy that now emphasizes target-organ protection. Sodium-glucose transporter 2 inhibitors is an extremely important class of antidiabetic medications that, in addition to their glucose lowering effect, also exhibit cardio- and renoprotective effects. Various established and novel biomarkers have been described, reflecting kidney and cardiovascular function. In this review, we investigated the changes in established but also novel biomarkers of kidney, heart and vascular function associated with sodium-glucose transporter 2 inhibitors treatment in patients with type 2 diabetes mellitus.

Metabolic Syndrome and Cardiac Remodeling Due to Mitochondrial Oxidative Stress Involving Gliflozins and Sirtuins

PURPOSE OF REVIEW

To address the mechanistic pathways focusing on mitochondria dysfunction, oxidative stress, sirtuins imbalance, and other contributors in patient with metabolic syndrome and cardiovascular disease. Sodium glucose co-transporter type 2 (SGLT-2) inhibitors deeply influence these mechanisms. Recent randomized clinical trials have shown impressive results in improving cardiac function and reducing cardiovascular and renal events. These unexpected results generate the need to deepen our understanding of the molecular mechanisms able to generate these effects to help explain such significant clinical outcomes.

RECENT FINDINGS

Cardiovascular disease is highly prevalent among individuals with metabolic syndrome and diabetes. Furthermore, mitochondrial dysfunction is a principal player in its development and persistence, including the consequent cardiac remodeling and events. Another central protagonist is the renin-angiotensin system; the high angiotensin II (Ang II) activity fuel oxidative stress and local inflammatory responses. Additionally, sirtuins decline plays a pivotal role in the process; they enhance oxidative stress by regulating adaptive responses to the cellular environment and interacting with Ang II in many circumstances, including cardiac and vascular remodeling, inflammation, and fibrosis. Fasting and lower mitochondrial energy generation are conditions that substantially reduce most of the mentioned cardiometabolic syndrome disarrangements. In addition, it increases sirtuins levels, and adenosine monophosphate-activated protein kinase (AMPK) signaling stimulates hypoxia-inducible factor-1β (HIF-1 beta) and favors ketosis. All these effects favor autophagy and mitophagy, clean the cardiac cells with damaged organelles, and reduce oxidative stress and inflammatory response, giving cardiac tissue protection. In this sense, SGLT-2 inhibitors enhance the level of at least four sirtuins, some located in the mitochondria. Moreover, late evidence shows that SLGT-2 inhibitors mimic this protective process, improving mitochondria function, oxidative stress, and inflammation. Considering the previously described protection at the cardiovascular level is necessary to go deeper in the knowledge of the effects of SGLT-2 inhibitors on the mitochondria function. Various of the protective effects these drugs clearly had shown in the trials, and we briefly describe it could depend on sirtuins enhance activity, oxidative stress reduction, inflammatory process attenuation, less interstitial fibrosis, and a consequent better cardiac function. This information could encourage investigating new therapeutic strategies for metabolic syndrome, diabetes, heart and renal failure, and other diseases.

A Comparative Study on the Efficacy and Safety of Dose Escalation of Luseogliflozin in Type 2 Diabetes Mellitus Patients With Poor Glycemic Control

Objective In this study, we aimed to assess the safety and efficacy of the dose escalation of luseogliflozin (LUSEO) in type 2 diabetes mellitus (T2DM) patients with poor glycemic control. To that end, we compared two groups assigned to two different doses of luseogliflozin (LUSEO) for 12 weeks. Methods Patients with a hemoglobin A1c (HbA1c) level of 7% or higher already on treatment with luseogliflozin 2.5 mg/day for 12 weeks or longer were randomly assigned to either the 2.5-mg/day group (control group) or the 5-mg/day group (dose-escalation group) of luseogliflozin through the envelope method and were treated for 12 weeks. Blood and urine samples were collected at two different time points: at weeks 0 and 12 after randomization. The primary outcome was the change in HbA1c from the baseline to 12 weeks. The secondary outcomes were changes in the body mass index (BMI), body weight (BW), blood pressure (BP), fasting plasma glucose (FPG), lipid parameters, hepatic function, or renal function from the baseline to 12 weeks. Results Based on our findings, HbA1c levels significantly decreased in the dose-escalation group when compared to the control group (p<0.001) at week 12. Conclusion For T2DM patients with poor glycemic control under treatment with LUSEO at a dose of 2.5 mg, dose escalation of LUSEO to 5 mg safely improved glycemic control, and this might prove to be an effective and safe treatment option.

Antiarrhythmic effects and mechanisms of sodium-glucose cotransporter 2 inhibitors: A mini review

Sodium-glucose cotransporter 2 inhibitors (SGLT2i) are a new type of oral hypoglycaemic agent with good cardiovascular protective effects. There are several lines of clinical evidence suggest that SGLT2i can significantly reduce the risks of heart failure, cardiovascular death, and delay the progression of chronic kidney disease. In addition, recent basic and clinical studies have also reported that SGLT2i also has good anti-arrhythmic effects. However, the exact mechanism is poorly understood. The aim of this review is to summarize recent clinical findings, studies of laboratory animals, and related study about this aspect of the antiarrhythmic effects of SGLT2i, to further explore its underlying mechanisms, safety, and prospects for clinical applications of it.

SGLT2 inhibitor dapagliflozin reduces endothelial dysfunction and microvascular damage during cardiac ischemia/reperfusion injury through normalizing the XO-SERCA2-CaMKII-coffilin pathways

Background: Given the importance of microvascular injury in infarct formation and expansion, development of therapeutic strategies for microvascular protection against myocardial ischemia/reperfusion injury (IRI) is of great interest. Here, we explored the molecular mechanisms underlying the protective effects of the SGLT2 inhibitor dapagliflozin (DAPA) against cardiac microvascular dysfunction mediated by IRI. Methods: DAPA effects were evaluated both in vivo, in mice subjected to IRI, and in vitro, in human coronary artery endothelial cells (HCAECs) exposed to hypoxia/reoxygenation (H/R). DAPA pretreatment attenuated luminal stenosis, endothelial swelling, and inflammation in cardiac microvessels of IRI-treated mice. Results: In H/R-challenged HCAECs, DAPA treatment improved endothelial barrier function, endothelial nitric oxide synthase (eNOS) activity, and angiogenic capacity, and inhibited H/R-induced apoptosis by preventing cofilin-dependent F-actin depolymerization and cytoskeletal degradation. Inhibition of H/R-induced xanthine oxidase (XO) activation and upregulation, sarco(endo)plasmic reticulum calcium-ATPase 2 (SERCA2) oxidation and inactivation, and cytoplasmic calcium overload was further observed in DAPA-treated HCAECs. DAPA also suppressed calcium/Calmodulin (CaM)-dependent kinase II (CaMKII) activation and cofilin phosphorylation, and preserved cytoskeleton integrity and endothelial cell viability following H/R. Importantly, the beneficial effects of DAPA on cardiac microvascular integrity and endothelial cell survival were largely prevented in IRI-treated SERCA2-knockout mice. Conclusions: These results indicate that DAPA effectively reduces cardiac microvascular damage and endothelial dysfunction during IRI through inhibition of the XO-SERCA2-CaMKII-cofilin pathway.

Mechanisms and Clinical Implications of Endothelial Dysfunction in Arterial Hypertension

The endothelium is composed of a monolayer of endothelial cells, lining the interior surface of blood and lymphatic vessels. Endothelial cells display important homeostatic functions, since they are able to respond to humoral and hemodynamic stimuli. Thus, endothelial dysfunction has been proposed as a key and early pathogenic mechanism in many clinical conditions. Given the relevant repercussions on cardiovascular risk, the complex interplay between endothelial dysfunction and systemic arterial hypertension has been a matter of study in recent years. Numerous articles have been published on this issue, all of which contribute to providing an interesting insight into the molecular mechanisms of endothelial dysfunction in arterial hypertension and its role as a biomarker of inflammation, oxidative stress, and vascular disease. The prognostic and therapeutic implications of endothelial dysfunction have also been analyzed in this clinical setting, with interesting new findings and potential applications in clinical practice and future research. The aim of this review is to summarize the pathophysiology of the relationship between endothelial dysfunction and systemic arterial hypertension, with a focus on the personalized pharmacological and rehabilitation strategies targeting endothelial dysfunction while treating hypertension and cardiovascular comorbidities.

Cellular interplay between cardiomyocytes and non-myocytes in diabetic cardiomyopathy

Patients with Type 2 diabetes mellitus (T2DM) frequently exhibit a distinctive cardiac phenotype known as diabetic cardiomyopathy. Cardiac complications associated with T2DM include cardiac inflammation, hypertrophy, fibrosis and diastolic dysfunction in the early stages of the disease, which can progress to systolic dysfunction and heart failure. Effective therapeutic options for diabetic cardiomyopathy are limited and often have conflicting results. The lack of effective treatments for diabetic cardiomyopathy is due in part, to our poor understanding of the disease development and progression, as well as a lack of robust and valid preclinical human models that can accurately recapitulate the pathophysiology of the human heart. In addition to cardiomyocytes, the heart contains a heterogeneous population of non-myocytes including fibroblasts, vascular cells, autonomic neurons and immune cells. These cardiac non-myocytes play important roles in cardiac homeostasis and disease, yet the effect of hyperglycaemia and hyperlipidaemia on these cell types are often overlooked in preclinical models of diabetic cardiomyopathy. The advent of human induced pluripotent stem cells provides a new paradigm in which to model diabetic cardiomyopathy as they can be differentiated into all cell types in the human heart. This review will discuss the roles of cardiac non-myocytes and their dynamic intercellular interactions in the pathogenesis of diabetic cardiomyopathy. We will also discuss the use of sodium-glucose cotransporter 2 inhibitors as a therapy for diabetic cardiomyopathy and their known impacts on non-myocytes. These developments will no doubt facilitate the discovery of novel treatment targets for preventing the onset and progression of diabetic cardiomyopathy.

Phenomapping-Derived Tool to Individualize the Effect of Canagliflozin on Cardiovascular Risk in Type 2 Diabetes

OBJECTIVE

Sodium-glucose cotransporter 2 (SGLT2) inhibitors have well-documented cardioprotective effects but are underused, partly because of high cost. We aimed to develop a machine learning-based decision support tool to individualize the atherosclerotic cardiovascular disease (ASCVD) benefit of canagliflozin in type 2 diabetes.

RESEARCH DESIGN AND METHODS

We constructed a topological representation of the Canagliflozin Cardiovascular Assessment Study (CANVAS) using 75 baseline variables collected from 4,327 patients with type 2 diabetes randomly assigned 1:1:1 to one of two canagliflozin doses (n = 2,886) or placebo (n = 1,441). Within each patient's 5% neighborhood, we calculated age- and sex-adjusted risk estimates for major adverse cardiovascular events (MACEs). An extreme gradient boosting algorithm was trained to predict the personalized ASCVD effect of canagliflozin using features most predictive of topological benefit. For validation, this algorithm was applied to the CANVAS-Renal (CANVAS-R) trial, comprising 5,808 patients with type 2 diabetes randomly assigned 1:1 to canagliflozin or placebo.

RESULTS

In CANVAS (mean age 60.9 ± 8.1 years; 33.9% women), 1,605 (37.1%) patients had a neighborhood hazard ratio (HR) more protective than the effect estimate of 0.86 reported for MACEs in the original trial. A 15-variable tool, INSIGHT, trained to predict the personalized ASCVD effects of canagliflozin in CANVAS, was tested in CANVAS-R (mean age 62.4 ± 8.4 years; 2,164 [37.3%] women), where it identified patient phenotypes with greater ASCVD canagliflozin effects (adjusted HR 0.60 [95% CI 0.41-0.89] vs. 0.99 [95% CI 0.76-1.29]; Pinteraction = 0.04).

CONCLUSIONS

We present an evidence-based, machine learning-guided algorithm to personalize the prescription of SGLT2 inhibitors for patients with type 2 diabetes for ASCVD effects.

An Overview of the Cardiorenal Protective Mechanisms of SGLT2 Inhibitors

Sodium-glucose co-transporter 2 (SGLT2) inhibitors block glucose reabsorption in the renal proximal tubule, an insulin-independent mechanism that plays a critical role in glycemic regulation in diabetes. In addition to their glucose-lowering effects, SGLT2 inhibitors prevent both renal damage and the onset of chronic kidney disease and cardiovascular events, in particular heart failure with both reduced and preserved ejection fraction. These unexpected benefits prompted changes in treatment guidelines and scientific interest in the underlying mechanisms. Aside from the target effects of SGLT2 inhibition, a wide spectrum of beneficial actions is described for the kidney and the heart, even though the cardiac tissue does not express SGLT2 channels. Correction of cardiorenal risk factors, metabolic adjustments ameliorating myocardial substrate utilization, and optimization of ventricular loading conditions through effects on diuresis, natriuresis, and vascular function appear to be the main underlying mechanisms for the observed cardiorenal protection. Additional clinical advantages associated with using SGLT2 inhibitors are antifibrotic effects due to correction of inflammation and oxidative stress, modulation of mitochondrial function, and autophagy. Much research is required to understand the numerous and complex pathways involved in SGLT2 inhibition. This review summarizes the current known mechanisms of SGLT2-mediated cardiorenal protection.

Effects of dapagliflozin in the progression of atherosclerosis in patients with type 2 diabetes: a meta-analysis of randomized controlled trials

AIMS

At present, an increasing number of studies are trying to determine whether dapagliflozin has a significant effect on the occurrence and development of atherosclerosis in patients with type 2 diabetes mellitus (T2DM), but there is no consensus. In addition, the former meta-analyses, relying on only a few previous studies and a minimal number of research indicators, have not been able to draw sufficient conclusions simultaneously. Consequently, we conducted a meta-analysis to evaluate the effectiveness of dapagliflozin in the occurrence and development of atherosclerosis in patients with T2DM.

METHODS

We searched electronic databases (PubMed, Embase, Cochrane, and Scopus) and reference lists in relevant papers for articles published in 2011-2021. We selected studies that evaluated the effects of dapagliflozin on the risk factors related to the occurrence or development of atherosclerosis in patients with T2DM. A fixed or random-effect model calculated the weighted average difference of dapagliflozin on efficacy, and the factors affecting heterogeneity were determined by Meta-regression analysis.

RESULTS

Twelve randomized controlled trials (18,758 patients) were incorporated in our meta-analysis. In contrast with placebo, dapagliflozin was associated with a significantly increase in high density lipoprotein-cholesterol (HDL-C) [MD = 1.39; 95% CI (0.77, 2.01); P < 0.0001], Δflow-mediated vasodilatation (ΔFMD) [MD = 1.22; 95% CI (0.38, 2.06); P = 0.005] and estimated Glomerular Filtration Rate(eGFR) [MD = 1.94; 95% CI (1.38, 2.51); P < 0.00001]. Furthermore, dapagliflozin had a tremendous advantage in controlling triglycerides (TG) in subgroups whose baseline eGFR < 83 ml/min/1.73m2 [MD = - 10.38; 95% CI (- 13.15, - 7.60); P < 0.00001], systolic blood pressure (SBP) [MD = - 2.82; 95% CI (- 3.22, - 2.42); P < 0.00001], HbA1c, BMI, body weight and waist circumference. However, dapagliflozin has an adverse effect on increasing total cholesterol (TC) and low-density lipoprotein-cholesterol (LDL-C). Besides, there were no significant changes in other indicators, including adiponectin and C-peptide immunoreactivity.

CONCLUSIONS

Our pooled analysis suggested that dapagliflozin has a terrifically better influence over HDL-C, ΔFMD, and eGFR, and it concurrently had a tremendous advantage in controlling TG, SBP, DBP, HbA1c, BMI, body weight, and waist circumference, but it also harms increasing TC and LDL-C. Furthermore, this study found that the effect of dapagliflozin that decreases plasma levels of TG is only apparent in subgroups of baseline eGFR < 83 ml/min/1.73m2, while the subgroup of baseline eGFR ≥ 83 ml/min/1.73m2 does not. Finally, the above results summarize that dapagliflozin could be a therapeutic option for the progression of atherosclerosis in patients with T2DM. Systematic review registration PROSPERO CRD42021278939.

The Enhanced Cardiac Outcome of Conjugated SGLT2 Inhibitors and GLP-1RA Therapy in Diabetic Patients

PURPOSE OF REVIEW

Cardiovascular disease secondary to diabetes continues to threaten the survivability of many people all over the world. We assess the most recent findings of synergistic effects of combined glucagon-like peptide 1 receptor agonists (GLP-1RAs) and sodium-glucose cotransporter 2 (SGLT2) inhibitors in lowering cardiac complications in the diabetic population. We describe drug therapies' mechanism of action, postulated cardioprotective process, the additive value of conjugated therapy, and analyze recently reported study and its limitation.

RECENT FINDINGS

SGLT2 inhibitors and GLP-1RAs have gained popularity due to their ability to reduce major adverse cardiovascular events in diabetic patients. There is emerging evidence of the additional cardiovascular benefit from the combined application of SGLT2 inhibitors and GLP-1RAs therapy demonstrated by a recent real-world cohort study. Reducing cardiac mortality in patients with diabetes by administering dual antihyperglycemic therapies (GLP-1Rs and SGLT2 inhibitors) might play a key role in the future treatment of the diabetic population.

Effects of SGLT-2 Inhibitors on Vascular Endothelial Function and Arterial Stiffness in Subjects With Type 2 Diabetes: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

OBJECTIVE

This systematic review and meta-analysis aimed to evaluate the effects of SGLT-2 inhibitors (SGLT-2i) on endothelial function and arteriosclerosis in diabetic patients.

METHODS

Randomized controlled trials (RCTs) were retrieved from PubMed, Embase, Cochrane Library, and Web of Science databases to evaluate the effects of SGLT-2i on endothelial function and atherosclerosis in type 2 diabetic patients.

RESULTS

We selected 9 RCTs and 2 cohort studys involving 868 patients. Of these, six studies provided flow-mediated dilation (FMD) levels before and after the intervention. The pooled analysis showed that SGLT-2i could significantly improve the FMD compared to the control group (SMD: 0.18, 95% CI: 0.02 ~ 0.34, P = 0.03). Three studies provided the change in FMD before and after the intervention. Pooled analysis showed no significant differences in FMD change between the SGLT-2i group and the control group. (MD: 2.1, 95%-CI: -0.11~4.31, P = 0.06). Five studies showed pulse wave velocity (PWV) results. Pooled analysis showed no significant differences in the change in PWV between the SGLT-2i group and the control group (SMD: 0.11, 95%-CI: - 0.15 ~ 0.37, P = 0.4).

CONCLUSIONS

The ability of SGLT-2 inhibitors to improve FMD was significant, but there was no significant effect on PWV levels. SGLT-2i was superior to other antidiabetic agents in improving arterial endothelial function.

Cardiovascular Benefits from Gliflozins: Effects on Endothelial Function

Type 2 diabetes mellitus (T2DM) is a known independent risk factor for atherosclerotic cardiovascular disease (CVD) and solid epidemiological evidence points to heart failure (HF) as one of the most common complications of diabetes. For this reason, it is imperative to consider the prevention of CV outcomes as an effective goal for the management of diabetic patients, as important as lowering blood glucose. Endothelial dysfunction (ED) is an early event of atherosclerosis involving adhesion molecules, chemokines, and leucocytes to enhance low-density lipoprotein oxidation, platelet activation, and vascular smooth muscle cell proliferation and migration. This abnormal vascular phenotype represents an important risk factor for the genesis of any complication of diabetes, contributing to the pathogenesis of not only macrovascular disease but also microvascular damage. Gliflozins are a novel class of anti-hyperglycemic agents used for the treatment of Type 2 diabetes mellitus (T2DM) that selectively inhibit the sodium glucose transporter 2 (SGLT2) in the kidneys and have provoked large interest in scientific community due to their cardiovascular beneficial effects, whose underlying pathophysiology is still not fully understood. This review aimed to analyze the cardiovascular protective mechanisms of SGLT2 inhibition in patients T2DM and their impact on endothelial function.

Pathophysiological Association between Diabetes Mellitus and Endothelial Dysfunction

Endothelial dysfunction plays a critical role in atherosclerosis progression, leading to cardiovascular complications. There are significant associations between diabetes mellitus, oxidative stress, and endothelial dysfunction. Oxidative stress is increased by chronic hyperglycemia and acute glucose fluctuations induced by postprandial hyperglycemia in patients with diabetes mellitus. In addition, selective insulin resistance in the phosphoinositide 3-kinase/Akt/endothelial nitric oxide (NO) synthase pathway in endothelial cells is involved in decreased NO production and increased endothelin-1 production from the endothelium, resulting in endothelial dysfunction. In a clinical setting, selecting an appropriate therapeutic intervention that improves or augments endothelial function is important for preventing diabetic vascular complications. Hypoglycemic drugs that reduce glucose fluctuations by decreasing the postprandial rise in blood glucose levels, such as glinides, α-glucosidase inhibitors and dipeptidyl peptidase 4 inhibitors, and hypoglycemic drugs that ameliorate insulin sensitivity, such as thiazolidinediones and metformin, are expected to improve or augment endothelial function in patients with diabetes. Glucagon-like peptide 1 receptor agonists, metformin, and sodium-glucose cotransporter 2 inhibitors may improve endothelial function through multiple mechanisms, some of which are independent of glucose control or insulin signaling. Oral administration of antioxidants is not recommended in patients with diabetes due to the lack of evidence for the efficacy against diabetic complications.

Effects of Sodium-Glucose Co-Transporter 2 Inhibitors on Vascular Cell Function and Arterial Remodeling

Cardiovascular disease is the leading cause of morbidity and mortality in diabetes. Recent clinical studies indicate that sodium-glucose co-transporter 2 (SGLT2) inhibitors improve cardiovascular outcomes in patients with diabetes. The mechanism underlying the beneficial effect of SGLT2 inhibitors is not completely clear but may involve direct actions on vascular cells. SGLT2 inhibitors increase the bioavailability of endothelium-derived nitric oxide and thereby restore endothelium-dependent vasodilation in diabetes. In addition, SGLT2 inhibitors favorably regulate the proliferation, migration, differentiation, survival, and senescence of endothelial cells (ECs). Moreover, they exert potent antioxidant and anti-inflammatory effects in ECs. SGLT2 inhibitors also inhibit the contraction of vascular smooth muscle cells and block the proliferation and migration of these cells. Furthermore, studies demonstrate that SGLT2 inhibitors prevent postangioplasty restenosis, maladaptive remodeling of the vasculature in pulmonary arterial hypertension, the formation of abdominal aortic aneurysms, and the acceleration of arterial stiffness in diabetes. However, the role of SGLT2 in mediating the vascular actions of these drugs remains to be established as important off-target effects of SGLT2 inhibitors have been identified. Future studies distinguishing drug- versus class-specific effects may optimize the selection of specific SGLT2 inhibitors in patients with distinct cardiovascular pathologies.

The Potential Roles of Osmotic and Nonosmotic Sodium Handling in Mediating the Effects of Sodium-Glucose Cotransporter 2 Inhibitors on Heart Failure

Concomitant type 2 diabetes and chronic kidney disease increases the risk of heart failure. Recent studies demonstrate beneficial effects of sodium-glucose cotransporter 2 (SGLT2) inhibitors on chronic kidney disease progression and heart failure hospitalization in patients with and without diabetes. In addition to inhibiting glucose reabsorption, SGLT2 inhibitors decrease proximal tubular sodium reabsorption, possibly leading to transient natriuresis. We review the hypothesis that SGLT2 inhibitor’s natriuretic and osmotic diuretic effects mediate their cardioprotective effects. The degree to which these benefits are related to changes in sodium, independent of the kidney, is currently unknown. Aside from effects on osmotically active sodium, we explore the intriguing possibility that SGLT2 inhibitors could also modulate nonosmotic sodium storage. This alternative hypothesis is based on emerging literature that challenges the traditional 2-compartment model of sodium balance to provide support for a 3-compartment model that includes the binding of sodium to glycosaminoglycans, such as those in muscles and skin. This recent research on nonosmotic sodium storage, as well as direct cardiac effects of SGLT2 inhibitors, provides possibilities for other ways in which SGLT2 inhibitors might mitigate heart failure risk. Overall, we review the effects of SGLT2 inhibitors on sodium balance and sensitivity, cardiac tissue, interstitial fluid and plasma volume, and nonosmotic sodium storage.

SGLT2 inhibitors have cardiovascular benefits that include HF outcomes in patients with and without diabetes. Because the underlying mechanisms are only partly explained by improvements in BP, body weight, or glucose control, other mechanisms have been proposed. We focus here on a central role for effects on sodium as underlying the positive benefits of SGLT2 inhibitors in HF. We explore the new (although still unconfirmed) idea that SGLT2 inhibitors exert some of their positive effects by affecting nonosmotic sodium (ie, sodium bound to muscles and skin and not dissolved in the blood).

SGLT2 inhibitors have emerged as a class of drugs, previously prescribed for patients with T2D, that have in more recent years been shown to have substantial heart and kidney clinical benefits in patients with and without T2D.

The degree to which these benefits are related to kidney-independent changes in sodium homeostasis is currently unknown.

A better understanding of the nonosmotic mechanisms underpinning the benefits of SGLT2 inhibition on HF (with reduced or preserved left ventricular ejection fraction) may allow researchers to assess the effects of SGLT2 inhibitors in combination with other treatments that affect sodium balance.

Impact of Sodium-Glucose Co-Transporter 2 Inhibitors on Cardiac Protection

Sodium–glucose co-transporter 2 (SGLT2) inhibitors have been approved as a new class of anti-diabetic drugs for type 2 diabetes mellitus (T2DM). The SGLT2 inhibitors reduce glucose reabsorption through renal systems, thus improving glycemic control in all stages of diabetes mellitus, independent of insulin. This class of drugs has the advantages of no clinically relevant hypoglycemia and working in synergy when combined with currently available anti-diabetic drugs. While improving sugar level control in these patients, SGLT2 inhibitors also have the advantages of blood-pressure improvement and bodyweight reduction, with potential cardiac and renal protection. In randomized control trials for patients with diabetes, SGLT2 inhibitors not only improved cardiovascular and renal outcomes, but also hospitalization for heart failure, with this effect extending to those without diabetes mellitus. Recently, dynamic communication between autophagy and the innate immune system with Beclin 1-TLR9-SIRT3 complexes in response to SGLT2 inhibitors that may serve as a potential treatment strategy for heart failure was discovered. In this review, the background molecular pathways leading to the clinical benefits are examined in this new class of anti-diabetic drugs, the SGLT2 inhibitors.

Impact of SGLT2 Inhibitors on Heart Failure: From Pathophysiology to Clinical Effects

Heart failure (HF) affects up to over 20% of patients with type 2 diabetes (T2DM), even more in the elderly. Although, in T2DM, both hyperglycemia and the proinflammatory status induced by insulin resistance are crucial in cardiac function impairment, SGLT2i cardioprotective mechanisms against HF are several. In particular, these beneficial effects seem attributable to the significant reduction of intracellular sodium levels, well-known to exert a cardioprotective role in the prevention of oxidative stress and consequent cardiomyocyte death. From a molecular perspective, patients’ exposure to gliflozins’ treatment mimics nutrient and oxygen deprivation, with consequent autophagy stimulation. This allows to maintain the cellular homeostasis through different degradative pathways. Thus, since their introduction in the clinical practice, the hypotheses on SGLT2i mechanisms of action have changed: from simple glycosuric drugs, with consequent glucose lowering, erythropoiesis enhancing and ketogenesis stimulating, to intracellular sodium-lowering molecules. This provides their consequent cardioprotective effect, which justifies its significant reduction in CV events, especially in populations at higher risk. Finally, the updated clinical evidence of SGLT2i benefits on HF was summarized. Thus, this review aimed to analyze the cardioprotective mechanisms of sodium glucose transporter 2 inhibitors (SGLT2i) in patients with HF, as well as their clinical impact on cardiovascular events.

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.

Endothelial function and dysfunction: Impact of sodium-glucose cotransporter 2 inhibitors

Diabetes mellitus is associated with endothelial dysfunction that leads to cardiovascular complications. Sodium-glucose cotransporter 2 (SGLT2) inhibitors demonstrated efficacy in glycemic control in type 2 diabetes patients with positive cardiovascular outcome. Recent research revealed a link between SGLT2 inhibition and improved macro- and microvascular endothelial functions. Mechanisms underlying this phenomenon could be due to the role of SLGT2 in the regulation of endothelial physiology. In this review, current knowledge and hypothesis on the link between SGLT2 and endothelial function were critically appraised and the impact of SGLT2 inhibitors on endothelial dysfunction in pre-clinical and clinical studies was discussed.

Association between lipid profile and endothelial dysfunction as assessed by the reactive hyperemia index

INTRODUCTION

We investigated the associations between endothelial dysfunction (ED) as evaluated by the reactive hyperemia index (RHI) obtained using Endo-PAT2000® and atherosclerotic risk factors in patients who underwent coronary artery angiography (CAG).

METHODS

The subjects consisted of 191 patients who were clinically suspected to have CAD and underwent CAG, and in whom we could perform Endo-PAT2000®. We divided the patients into ED (RHI<1.67, n = 71) and non-ED (RHI≥1.67, n = 120) groups.

RESULTS

The ED group was significantly older and showed a higher ratio of low-density lipoprotein cholesterol (LDL-C) to high-density lipoprotein cholesterol (HDL-C) (L/H) than the non-ED group. A multivariate logistic regression analysis was performed to examine the associations between the presence of ED and age, gender, and BMI in addition to L/H. Age [odds ratio (OR) = 1.03, p = .02] and L/H (OR = 1.64, p = .01) were identified as significant independent markers of the presence of ED. Next, we divided 122 patients with statin treatment into ED (n = 40) and non-ED (n = 82) groups. The ED group tended to have higher L/H and lower HDL-C than the non-ED group. HDL-C (OR = 0.95, p = .01) and age (OR = 1.05, p = .04) were identified as independent markers of the presence of ED.

CONCLUSIONS

L/H was an independent marker of the presence of ED in patients without dyslipidemia. In addition, among patients with statin treatment, HDL-C was an independent marker of the presence of ED.

Ketogenic Diets and Cardio-Metabolic Diseases

While the prevalence of cardio-metabolic diseases (CMDs) has become a worldwide epidemic, much attention is paid to managing CMDs effectively. A ketogenic diet (KD) constitutes a high-fat and low-carbohydrate diet with appropriate protein content and calories. KD has drawn the interests of clinicians and scientists regarding its application in the management of metabolic diseases and related disorders; thus, the current review aimed to examine the evidences surrounding KD and the CMDs to draw the clinical implications. Overall, KD appears to play a significant role in the therapy of various CMDs, which is manifested by the effects of KDs on cardio-metabolic outcomes. KD therapy is generally promising in obesity, heart failure, and hypertension, though different voices still exist. In diabetes and dyslipidemia, the performance of KD remains controversial. As for cardiovascular complications of metabolic diseases, current evidence suggests that KD is generally protective to obese related cardiovascular disease (CVD), while remaining contradictory to diabetes and other metabolic disorder related CVDs. Various factors might account for the controversies, including genetic background, duration of therapy, food composition, quality, and sources of KDs. Therefore, it's crucial to perform more rigorous researches to focus on clinical safety and appropriate treatment duration and plan of KDs.

Effects of external counter-pulsation on endothelial function assessed by peripheral artery tonometry, levels of glycaemia and metabolic markers in individuals with type 2 diabetes mellitus

BACKGROUND AND AIMS

External counter-pulsation (ECP) generates sheer stress thereby improving endothelial function and anginal symptoms in coronary artery disease. Endothelial dysfunction is also involved in the pathogenesis of T2DM. The aim of this pilot study was to investigate the use of ECP at different doses in improving endothelial function and glycaemic markers in T2DM.

METHODS

This prospective study involved 46 subjects with T2DM randomly assigned to receive 35 sessions of ECP at different regimens (0.5 h versus 1 h) and duration (7 versus 12 weeks). Endothelial function was evaluated by reactive hyperaemia index (RHI) via peripheral arterial tonometry at the start, midpoint and end of study. Other secondary outcomes included fasting glucose, HOMA-IR, HbA1c, blood pressure, lipid profile, weight and vibration sense.

RESULTS

There was no change in RHI across all 3 regimens of ECP individually or collectively at the end of the study (ΔRHI +0.01%, p = 0.458). Glycaemic markers also remained unchanged at endpoint. Subgroup analysis showed an improvement in RHI (ΔRHI +20.6%, p = 0.0178) in subjects with more severe endothelial dysfunction at baseline.

CONCLUSION

ECP did not show a beneficial effect on endothelial function or glycemic control in this South-East Asian population with T2DM at any of the three regimens. This may partly be explained by less severe endothelial dysfunction and less insulin resistance in our population at baseline.

Major adverse cardiovascular and limb events in patients with diabetes and concomitant peripheral artery disease treated with sodium glucose cotransporter 2 inhibitor versus dipeptidyl peptidase-4 inhibitor

Background

Whether sodium glucose co-transporter 2 inhibitors (SGLT2i) are associated with a lower risk of cardiovascular as well as adverse lower limb events in patients with type-2 diabetes mellitus (T2DM) and concomitant peripheral artery disease (PAD) is unclear.

We aimed to evaluate the risk of cardiovascular and limb events, and death associated with the use of SGLT2i compared with dipeptidyl peptidase-4 inhibitors (DPP4i) among a longitudinal and national cohort of patients with T2DM.

Methods

In this nationwide retrospective cohort study based on the Taiwan National Health Insurance Research Database, we identified a total of 11,431 and 93,972 consecutive T2DM patients with PAD taking SGLT2i and DPP4i, respectively, from May 1, 2016, to December 31, 2017. We used 1:1 propensity score matching (PSM) to balance covariates across study groups. Patients were followed from the drug index date until the occurrence of clinical outcomes, death, discontinuation of the index drug, or the end of the study period, whichever occurred first.

Results

Overall, 56% and 44% of the patients were treated with dapagliflozin and empagliflozin, respectively. The use of SGLT2i had comparable risks of ischemic stroke and acute myocardial infarction, and was associated with lower risks of congestive heart failure (CHF) [hazard ratio (HR): 0.66; 95% confidence interval (CI) 0.49–0.89; p = 0.0062], lower limb ischemia requiring revascularization (HR: 0.73; 95% CI 0.54–0.98; p = 0.0367) or amputation (HR: 0.43; 95% CI 0.30–0.62; p < 0.0001), and cardiovascular death (HR: 0.67; 95% CI 0.49–0.90; p = 0.0089) when compared with the DDP4i group after PSM. The subgroup analysis revealed consistent results for CHF and major adverse limb outcomes for SGLT2i versus DPP4i among patients aged ≥ 75 years, the presence of chronic kidney disease and established cardiovascular disease was consistent with the main analysis.

Conclusions

SGLT2i were associated with lower risks of CHF and adverse lower limb events compared with DPP4i among patients with T2DM and PAD in real-world practice.

A metabolomics-based molecular pathway analysis of how the sodium-glucose co-transporter-2 inhibitor dapagliflozin may slow kidney function decline in patients with diabetes

AIM

To investigate which metabolic pathways are targeted by the sodium-glucose co-transporter-2 inhibitor dapagliflozin to explore the molecular processes involved in its renal protective effects.

METHODS

An unbiased mass spectrometry plasma metabolomics assay was performed on baseline and follow-up (week 12) samples from the EFFECT II trial in patients with type 2 diabetes with non-alcoholic fatty liver disease receiving dapagliflozin 10 mg/day (n = 19) or placebo (n = 6). Transcriptomic signatures from tubular compartments were identified from kidney biopsies collected from patients with diabetic kidney disease (DKD) (n = 17) and healthy controls (n = 30) from the European Renal cDNA Biobank. Serum metabolites that significantly changed after 12 weeks of dapagliflozin were mapped to a metabolite-protein interaction network. These proteins were then linked with intra-renal transcripts that were associated with DKD or estimated glomerular filtration rate (eGFR). The impacted metabolites and their protein-coding transcripts were analysed for enriched pathways.

RESULTS

Of all measured (n = 812) metabolites, 108 changed (P < 0.05) during dapagliflozin treatment and 74 could be linked to 367 unique proteins/genes. Intra-renal mRNA expression analysis of the genes encoding the metabolite-associated proteins using kidney biopsies resulted in 105 genes that were significantly associated with eGFR in patients with DKD, and 135 genes that were differentially expressed between patients with DKD and controls. The combination of metabolites and transcripts identified four enriched pathways that were affected by dapagliflozin and associated with eGFR: glycine degradation (mitochondrial function), TCA cycle II (energy metabolism), L-carnitine biosynthesis (energy metabolism) and superpathway of citrulline metabolism (nitric oxide synthase and endothelial function).

CONCLUSION

The observed molecular pathways targeted by dapagliflozin and associated with DKD suggest that modifying molecular processes related to energy metabolism, mitochondrial function and endothelial function may contribute to its renal protective effect.

Secondary analyses to assess the profound effects of empagliflozin on endothelial function in patients with type 2 diabetes and established cardiovascular diseases: The placebo-controlled double-blind randomized effect of empagliflozin on endothelial function in cardiovascular high risk diabetes mellitus: Multi-center placebo-controlled double-blind randomized trial

Aims/Introduction

Recent clinical trials on sodium–glucose cotransporter 2 inhibitors showed improved outcomes in patients with type 2 diabetes at a high risk of cardiovascular events. However, the underlying effects on endothelial function remain unclear.

Materials and Methods

The effect of empagliflozin on endothelial function in cardiovascular high risk diabetes mellitus: Multi‐center placebo‐controlled double‐blind randomized (EMBLEM) trial in patients with type 2 diabetes and cardiovascular disease showed empagliflozin treatment for 24 weeks had no effect on peripheral endothelial function measured by reactive hyperemia peripheral arterial tonometry. This post‐hoc analysis of the EMBLEM trial included a detailed evaluation of the effects of empagliflozin on peripheral endothelial function in order to elucidate the clinical characteristics of responders or non‐responders to treatment.

Results

Of the 47 patients randomized into the empagliflozin group, 21 (44.7%) showed an increase in the reactive hyperemia index (RHI) after 24 weeks of intervention, with no apparent difference in the clinical characteristics between patients whose RHI either increased (at least >0) or did not increase. There was also no obvious difference between the treatment groups in the proportion of patients who had a clinically meaningful change (≥15%) in log‐transformed RHI. No correlation was found between changes in RHI and clinical variables, such as vital signs and laboratory parameters.

Conclusions

Treatment with empagliflozin for 24 weeks in patients with type 2 diabetes and cardiovascular disease did not affect peripheral endothelial function, and was not related to changes in clinical variables, including glycemic parameters. These findings suggest that the actions of sodium–glucose cotransporter 2 inhibitors other than direct improvement in peripheral endothelial function were responsible, at least in the early phase, for the clinical benefits found in recent cardiovascular outcome trials.

Rationale and design of an investigator-initiated, multicenter, prospective open-label, randomized trial to evaluate the effect of ipragliflozin on endothelial dysfunction in type 2 diabetes and chronic kidney disease: the PROCEED trial

Background

Type 2 diabetes (T2D) is associated with renal impairment and vascular endothelial dysfunction. Therefore, this pathological connection is an important therapeutic target. Recent cardiovascular and renal outcome trials demonstrated that sodium glucose cotransporter 2 inhibitors (SGLT2is) consistently reduced the risks of cardiovascular and renal events and mortality in patients with T2D and various other background risks including chronic kidney disease (CKD). However, the precise mechanisms by which SGLT2is accords these therapeutic benefits remain uncertain. It is also unknown whether these SGLT2is-associated benefits are associated with the amelioration of endothelial dysfunction in patients with T2D and CKD.

Methods

The PROCEED trial is an investigator-initiated, prospective, multicenter, open-label, randomized-controlled trial. The target sample size is 110 subjects. After they furnish informed consent and their endothelial dysfunction is confirmed from their decreased reactive hyperemia indices (RHI), eligible participants with T2D (HbA1c, 6.0–9.0%) and established CKD (30 mL/min/1.73 m² ≤ estimated glomerular filtration ratio [eGFR] < 60 and/or ≥ urine albumin-to-creatinine ratio 30 mg/g Cr) will be randomized (1:1) to receive either 50 mg ipragliflozin daily or continuation of background treatment (non-SGLT2i). The primary endpoint is the change in RHI from baseline after 24 weeks. To compare the treatment effects between groups, the baseline-adjusted means and their 95% confidence intervals will be estimated by analysis of covariance adjusted for HbA1c (< 7.0% or ≥ 7.0%), age (< 70 y or ≥ 70 y), RHI (< 1.67 or ≥ 1.67), eGFR (< 45 mL/min/1.73 m² or ≥ 45 mL/min/1.73 m²), and smoking status. Prespecified responder analyses will be also conducted to determine the proportions of patients with clinically meaningful changes in RHI at 24 weeks.

Discussion

PROCEED is the first trial to examine the effects of ipragliflozin on endothelial dysfunction in patients with T2D and CKD. This ongoing trial will establish whether endothelial dysfunction is a therapeutic target of SGLT2is in this population. It will also provide deep insights into the potential mechanisms by which SGLT2is reduced the risks of cardiovascular and renal events in recent outcome trials.

Trial registration Unique Trial Number, jRCTs071190054 (https://jrct.niph.go.jp/en-latest-detail/jRCTs071190054).

Reactive Hyperemia Index Associated With Atherosclerotic Cardiovascular Disease Under Treatment for Lifestyle Diseases

Background

Endothelial dysfunction is an early phase of atherosclerosis and causes atherosclerotic cardiovascular disease (ASCVD), but the cutoff reactive hyperemia index (RHI) for identifying ASCVD patients under treatment for lifestyle diseases is unknown.

Methods

Patients who visited Cardiology Section, Izumi General Medical Center, Kagoshima, Japan and were measured RHI using Endo-PAT 2000 during May 2014 and March 2016 were enrolled. We divided them into ASCVD and non-ASCVD groups and investigated the association with RHI between the groups.

Results

ASCVD group included 195 patients and non-ASCVD group included 288 patients. Age, body mass index and the rate of male, hypertension, diabetes, dyslipidemia and chronic kidney disease in the ASCVD group were significantly higher than those in non-ASCVD group. RHI in the ASCVD group (1.65 (1.40 - 1.92)) was significantly lower than that in the non-ASCVD group (1.73 (1.45 - 2.24)) (P < 0.05). In multi-regression analysis, RHI (odds ratio: 0.67, 95% confidence interval: 0.45 - 0.99, P = 0.04) was independently associated with ASCVD after adjusted by age, sex, body mass index, smoking, hypertension, diabetes, dyslipidemia and chronic kidney disease. The cutoff RHI value between the groups was 1.80.

Conclusion

RHI was significantly associated with ASCVD under treatment for lifestyle diseases and the cutoff value was 1.80.

Endothelium as a Therapeutic Target in Diabetes Mellitus: From Basic Mechanisms to Clinical Practice

Endothelium plays an essential role in human homeostasis by regulating arterial blood pressure, distributing nutrients and hormones as well as providing a smooth surface that modulates coagulation, fibrinolysis and inflammation. Endothelial dysfunction is present in Diabetes Mellitus (DM) and contributes to the development and progression of macrovascular disease, while it is also associated with most of the microvascular complications such as diabetic retinopathy, nephropathy and neuropathy. Hyperglycemia, insulin resistance, hyperinsulinemia and dyslipidemia are the main factors involved in the pathogenesis of endothelial dysfunction. Regarding antidiabetic medication, metformin, gliclazide, pioglitazone, exenatide and dapagliflozin exert a beneficial effect on Endothelial Function (EF); glimepiride and glibenclamide, dipeptidyl peptidase-4 inhibitors and liraglutide have a neutral effect, while studies examining the effect of insulin analogues, empagliflozin and canagliflozin on EF are limited. In terms of lipid-lowering medication, statins improve EF in subjects with DM, while data from short-term trials suggest that fenofibrate improves EF; ezetimibe also improves EF but further studies are required in people with DM. The effect of acetylsalicylic acid on EF is dose-dependent and lower doses improve EF while higher ones do not. Clopidogrel improves EF, but more studies in subjects with DM are required. Furthermore, angiotensin- converting-enzyme inhibitors /angiotensin II receptor blockers improve EF. Phosphodiesterase type 5 inhibitors improve EF locally in the corpus cavernosum. Finally, cilostazol exerts favorable effect on EF, nevertheless, more data in people with DM are required.

The New Biology of Diabetic Kidney Disease-Mechanisms and Therapeutic Implications

Diabetic kidney disease remains the most common cause of end-stage kidney disease in the world. Despite reductions in incidence rates of myocardial infarction and stroke in people with diabetes over the past 3 decades, the risk of diabetic kidney disease has remained unchanged, and may even be increasing in younger individuals afflicted with this disease. Accordingly, changes in public health policy have to be implemented to address the root causes of diabetic kidney disease, including the rise of obesity and diabetes, in addition to the use of safe and effective pharmacological agents to prevent cardiorenal complications in people with diabetes. The aim of this article is to review the mechanisms of pathogenesis and therapies that are either in clinical practice or that are emerging in clinical development programs for potential use to treat diabetic kidney disease.

Why the endothelium? The endothelium as a target to reduce diabetes-associated vascular disease

Over the past 66 years, our knowledge of the role of the endothelium in the regulation of cardiovascular function and dysfunction has advanced from the assumption that it is a single layer of cells that serves as a barrier between the blood stream and vascular smooth muscle to an understanding of its role as an essential endocrine-like organ. In terms of historical contributions, we pay particular credit to (1) the Canadian scientist Dr. Rudolf Altschul who, based on pathological changes in the appearance of the endothelium, advanced the argument in 1954 that "one is only as old as one's endothelium" and (2) the American scientist Dr. Robert Furchgott, a 1998 Nobel Prize winner in Physiology or Medicine, who identified the importance of the endothelium in the regulation of blood flow. This review provides a brief history of how our knowledge of endothelial function has advanced and now recognize that the endothelium produces a plethora of signaling molecules possessing paracrine, autocrine, and, arguably, systemic hormone functions. In addition, the endothelium is a therapeutic target for the anti-diabetic drugs metformin, glucagon-like peptide I (GLP-1) receptor agonists, and inhibitors of the sodium-glucose cotransporter 2 (SGLT2) that offset the vascular disease associated with diabetes.

Prognostic value of arterial stiffness measurements in cardiovascular disease, diabetes, and its complications: The potential role of sodium-glucose co-transporter-2 inhibitors

Type 2 diabetes mellitus (T2DM) constitutes a global pandemic, representing the 7th cause of death worldwide. Morbidity and mortality of patients with T2DM are gradually increasing, while prevalence of cardiovascular disease (CVD) among these patients is almost 14% greater compared to the general population. Arterial stiffness is nowadays a valuable biomarker of CVD and a promising treatment target in specific patient groups, including those suffering from T2DM. Despite that fact, design of the available studies cannot prove causal relationship. Recently, a new antidiabetic drug class, namely sodium-glucose co-transporter-2 (SGLT-2) inhibitors, has attracted scientific interest, due to their multiple, beneficial, pleiotropic effects, especially those focused on CVD. There is limited relevant literature concerning the effects of SGLT-2 inhibitors on arterial stiffness, while retrieved results might be considered as conflicting. The aim of the present review article is to summarize acquired knowledge regarding the prognostic role of arterial stiffness in T2DM, along with the presentation of retrieved data on the potential role of SGLT-2 inhibitors.

Prevention of cardiac allograft vasculopathy - A new possible indication for SGLT-2 inhibitors?

One of the main risk factors influencing patient survival after heart transplantation is cardiac allograft vasculopathy, the leading cause of death after the first year of transplantation. It is an entity of multifactorial origin including both humoral and cellular alloimmune responses as well as immunologic-independent factors such as graft injury, ischaemia-reperfusion injury, oxidative stress, cytomegalovirus infection, hyperlipidaemia, diabetes mellitus and hypertension. A fundamental characteristic of cardiac allograft vasculopathy is vascular remodelling, initially driven by the injury and apoptosis of endothelial cells, then by the migration of smooth muscle cells leading to intimal thickening and ultimately allograft vessel occlusion. Since cardiac allograft vasculopathy occurs within the first year of transplantation, prevention strategies should be implemented early. The disease could be partially prevented with overall cardiovascular risk reduction, mainly by controlling diabetes, hyperlipidemia and hypertension that can be related to the recipient but also induced or augmented by immunosuppressive drugs used. Current therapeutic options are only partially effective in postponing the development of vascular lesions. Diabetes is an important issue in the management of patients following cardiac transplantation. Although it is highly prevalent among heart transplant recipients (23% at 1 year increasing to 37% at 5 years after the procedure), no specific therapeutic protocols have been recommended yet. Sodium-glucose cotransporter-2 (SGLT-2) inhibitors are a novel class of antidiabetic drugs that produce glycosuric and natriuretic effects by inhibiting glucose and sodium reabsorption from the renal proximal tubules and have already shown benefits in cardiovascular outcome trials. Our hypothesis is that SGLT-2 inhibitors could prevent or delay the development of cardiac allograft vasculopathy targeting various mechanisms underpinning its pathogenesis due to their antidiabetic, antihypertensive, anti-inflammatory, antifibrotic, antioxidative and antiapoptotic effects, as well as through amelioration of endothelial dysfunction, ischaemia-reperfusion injury and modification of neurohumoral system. All the segments of the proposed theory that could interfere with evolution of vasculopathy are discussed separately within the main text. The implications for the science if the hypothesis were to be confirmed are as follows: prolongation of lifespan in heart transplant patients with diabetes, reduction of polypragmasia in posttransplant patients while targeting several mechanisms with one drug, and the possibility of spreading the indications even to patients without diabetes.

The Effects of Dapagliflozin on Systemic and Renal Vascular Function Display an Epigenetic Signature

CONTEXT

Mechanisms mediating the cardiovascular and renal protection exerted by SGLT2 inhibitors are still partially unknown. We investigated whether dapagliflozin modulates systemic and renal vascular function and structure, and induces epigenetic modifications.

SUBJECTS AND METHODS

Forty hypertensive patients with type 2 diabetes were randomly assigned to 4-week treatment with dapagliflozin 10 mg or hydrochlorothiazide (HCT) 12.5 mg. Routine analyses; plasma renin activity; aldosterone, catecholamine, and 24-hour urinary electrolyte levels; flow-mediated dilation (FMD) of the brachial artery; carotid-femoral pulse-wave velocity (PWV); augmentation index; and resistive index and dynamic renal resistive index (DRIN) were measured at baseline and after treatment. Circulating miRNAs (miRs) related to heart failure (miR30e-5p, miR199a-3p), endothelial dysfunction (miR27b and miR200b), and renal function (miR130b-3p, miR21-5p) were assessed and related to the effects of treatments.

RESULTS

Dapagliflozin and HCT marginally lowered blood pressure. Fasting glucose was lowered, whereas 24-hour diuresis, glycosuria, and osmolar clearance were increased by dapagliflozin (P < 0.001 for all), without affecting sodium excretion and glomerular filtration rate. Magnesium levels significantly increased after dapagliflozin treatment (P = 0.02). Neither dapagliflozin nor HCT modified FMD or PWV. DRIN did not vary in the dapagliflozin group, whereas it increased in the HCT group (P = 0.047 for time by treatment interaction). Both treatments induced variations in the expression of some miRs; dapagliflozin, but not HCT, significantly up-regulated miR30e-5p and downregulated miR199a-3p.

CONCLUSION

A putative epigenetic regulation of the protecting cardiovascular effect exerted by SGLT2 inhibitors was found. Dapagliflozin might exert nephroprotection by preserving renal vasodilating capacity.

SGLT2 Inhibitors: A Review of Their Antidiabetic and Cardioprotective Effects

Type 2 diabetes mellitus is a chronic metabolic disease associated with high cardiovascular (CV) risk. Sodium-glucose co-transporter 2 inhibitors (SGLT2i) are the latest class of antidiabetic medication that inhibit the absorption of glucose from the proximal tubule of the kidney and hence cause glycosuria. Four SGLT2i are currently commercially available in many countries: canagliflozin, dapagliflozin, empagliflozin, and ertugliflozin. SGLT2i reduce glycated hemoglobin by 0.5%-1.0% and have shown favorable effects on body weight, blood pressure, lipid profile, arterial stiffness and endothelial function. More importantly, SGLT2i have demonstrated impressive cardioprotective and renoprotective effects. The main mechanisms underlying their cardioprotective effects have been attributed to improvement in cardiac cell metabolism, improvement in ventricular loading conditions, inhibition of the Na+/H+ exchange in the myocardial cells, alteration in adipokines and cytokines production, as well as reduction of cardiac cells necrosis and cardiac fibrosis. The main adverse events of SGLT2i include urinary tract and genital infections, as well as euglycemic diabetic ketoacidosis. Concerns have also been raised about the association of SGLT2i with lower limb amputations, Fournier gangrene, risk of bone fractures, female breast cancer, male bladder cancer, orthostatic hypotension, and acute kidney injury.

SGLT-2 (Sodium-Glucose Cotransporter 2) Inhibition Reduces Ang II (Angiotensin II)-Induced Dissecting Abdominal Aortic Aneurysm in ApoE (Apolipoprotein E) Knockout Mice

OBJECTIVE

Abdominal aortic aneurysm (AAA) is a pathological condition of permanent vessel dilatation that predisposes to the potentially fatal consequence of aortic rupture. SGLT-2 (sodium-glucose cotransporter 2) inhibitors have emerged as powerful pharmacological tools for type 2 diabetes mellitus treatment. Beyond their glucose-lowering effects, recent studies have shown that SGLT-2 inhibitors reduce cardiovascular events and have beneficial effects on several vascular diseases such as atherosclerosis; however, the potential effects of SGLT-2 inhibition on AAA remain unknown. This study evaluates the effect of oral chronic treatment with empagliflozin-an SGLT-2 inhibitor-on dissecting AAA induced by Ang II (angiotensin II) infusion in apoE (apolipoprotein E)^-/- mice. Approach and Results: Empagliflozin treatment significantly reduced the Ang II-induced increase in maximal suprarenal aortic diameter in apoE^-/- mice independently of blood pressure effects. Immunohistochemistry analysis revealed that empagliflozin diminished Ang II-induced elastin degradation, neovessel formation, and macrophage infiltration at the AAA lesion. Furthermore, Ang II infusion resulted in a marked increase in the expression of chemokines (CCL-2 [chemokine (C-C motif) ligand 2] and CCL-5 [chemokine (C-C motif) ligand 5]), VEGF (vascular endothelial growth factor), and MMP (matrix metalloproteinase)-2 and MMP-9 in suprarenal aortic walls of apoE^-/- mice, and all were reduced by empagliflozin cotreatment. Western blot analysis revealed that p38 MAPK (p38 mitogen-activated protein kinase) and NF-κB (nuclear factor-κB) activation was also reduced in the suprarenal aortas of apoE^-/- mice cotreated with empagliflozin. Finally, in vitro studies in human aortic endothelial cells and macrophages showed that empagliflozin inhibited leukocyte-endothelial cell interactions and release of proinflammatory chemokines.

CONCLUSIONS

Pharmacological inhibition of SGLT-2 by empagliflozin inhibits AAA formation. SGLT-2 inhibition might represent a novel promising therapeutic strategy to prevent AAA progression.

Renoprotective Effects of Additional SGLT2 inhibitor Therapy in Patients With Type 2 Diabetes Mellitus and Chronic Kidney Disease Stages 3b-4: A Real World Report From A Japanese Specialized Diabetes Care Center

Background

Large randomized clinical trials of patients with type 2 diabetes mellitus (T2DM) and at high risk for cardiovascular disease revealed that sodium-glucose cotransporter 2 (SGLT2) inhibitors significantly reduced renal events. However, the trials included small numbers of patients with moderate-to-severe chronic kidney disease (CKD). Therefore, the renoprotective effects of SGLT2 inhibitors remain unknown in T2DM patients complicated with impaired renal function. We examined if SGLT2 inhibitors conferred beneficial effects on kidney function in T2DM patients with CKD.

Methods

We retrospectively recruited T2DM patients who were newly treated with add-on of SGLT2 inhibitors and suffered from moderate-to-severe renal impairment with CKD stages 3b-4 (15 < estimated glomerular filtration rate (eGFR) < 45 mL/min/1.73 m²), at initiation of SGLT2 inhibitor therapy. We analyzed T2DM patients with moderate-to-severe renal impairment who continued to use SGLT2 inhibitors for at least 1 year. We investigated the effects of SGLT2 inhibitor therapy on 1-year changes in eGFR and urinary protein excretion before and after the treatment.

Results

We analyzed 42 T2DM patients with median eGFR of 40.4 mL/min/1.73 m². One-year SGLT2 inhibitor therapy lowered median hemoglobin A1c (HbA1c) levels from 7.6% to 7.5% (not significant). Body weight and blood pressure were significantly decreased, and hemoglobin was significantly increased. The median value of eGFR after 1 year of SGLT2 inhibitor therapy was 41.0 mL/min/1.73 m², with no significant difference compared with baseline. The annual decline in eGFR improved significantly after SGLT2 inhibitor therapy (eGFR: (median), pre: -3.8, vs. post: 0.1 mL/min/1.73 m² per year, P < 0.01). We also found a significant decrease in urinary protein excretion after SGLT2 inhibitor therapy (urinary protein-to-creatinine ratio: (median), pre: 0.36, vs. post: 0.23 g/g creatinine, n = 35, P < 0.01).

Conclusions

This study revealed the promising observations that add-on treatment with SGLT2 inhibitors exerted significant renoprotective effects, culminating in improvements in annual decline in eGFR and urinary protein excretion in T2DM patients with CKD stages 3b-4, but did not significantly reduce HbA1c. Further prospective clinical trials are warranted to fully elucidate the effects of SGLT2 inhibitors on glycemic control and renal function in T2DM patients with moderate-to-severe renal impairment.

Beneficial Effects of Adiponectin on Glucose and Lipid Metabolism and Atherosclerotic Progression: Mechanisms and Perspectives

Circulating adiponectin concentrations are reduced in obese individuals, and this reduction has been proposed to have a crucial role in the pathogenesis of atherosclerosis and cardiovascular diseases associated with obesity and the metabolic syndrome. We focus on the effects of adiponectin on glucose and lipid metabolism and on the molecular anti-atherosclerotic properties of adiponectin and also discuss the factors that increase the circulating levels of adiponectin. Adiponectin reduces inflammatory cytokines and oxidative stress, which leads to an improvement of insulin resistance. Adiponectin-induced improvement of insulin resistance and adiponectin itself reduce hepatic glucose production and increase the utilization of glucose and fatty acids by skeletal muscles, lowering blood glucose levels. Adiponectin has also β cell protective effects and may prevent the development of diabetes. Adiponectin concentration has been found to be correlated with lipoprotein metabolism; especially, it is associated with the metabolism of high-density lipoprotein (HDL) and triglyceride (TG). Adiponectin appears to increase HDL and decrease TG. Adiponectin increases ATP-binding cassette transporter A1 and lipoprotein lipase (LPL) and decreases hepatic lipase, which may elevate HDL. Increased LPL mass/activity and very low density lipoprotein (VLDL) receptor and reduced apo-CIII may increase VLDL catabolism and result in the reduction of serum TG. Further, adiponectin has various molecular anti-atherosclerotic properties, such as reduction of scavenger receptors in macrophages and increase of cholesterol efflux. These findings suggest that high levels of circulating adiponectin can protect against atherosclerosis. Weight loss, exercise, nutritional factors, anti-diabetic drugs, lipid-lowering drugs, and anti-hypertensive drugs have been associated with an increase of serum adiponectin level.

Empagliflozin on top of metformin treatment improves arterial function in patients with type 1 diabetes mellitus

Background

Deteriorated arterial function and high incidence of cardiovascular events characterise diabetes mellitus. Metformin and recent antidiabetic drugs, SGLT2 inhibitors, reduce cardiovascular events. We explored the possible effects of empagliflozin’s effect on top of metformin treatment on endothelial function and arterial stiffness parameters in type 1 diabetes mellitus (T1DM) patients.

Methods

Forty T1DM patients were randomised into three treatment groups: (1) empagliflozin (25 mg daily), (2) metformin (2000 mg daily) and (3) empagliflozin/metformin (25 mg daily and 2000 mg daily, respectively). The fourth group received placebo. Arterial function was assessed at inclusion and after 12 weeks treatment by: endothelial function [brachial artery flow-mediated dilation (FMD), reactive hyperaemia index (RHI)], arterial stiffness [pulse wave velocity (PWV) and common carotid artery stiffness (β-stiffness)]. For statistical analysis one-way analysis of variance with Bonferroni post-test was used.

Results

Empagliflozin on top of metformin treatment significantly improved endothelial function as did metformin after 12 weeks of treatment: FMD [2.6-fold (P < 0.001) vs. 1.8-fold (P < 0.05)] and RHI [1.4-fold (P < 0.01) vs. 1.3-fold (P < 0.05)]. Empagliflozin on top of metformin treatment was superior to metformin in improving arterial stiffness parameters; it significantly improved PWV and β-stiffness compared to metformin [by 15.8% (P < 0.01) and by 36.6% (P < 0.05), respectively]. Metformin alone did not influence arterial stiffness.

Conclusion

Empagliflozin on top of metformin treatment significantly improved arterial stiffness compared to metformin in T1DM patients. Endothelial function was similarly improved in all treatment groups. Empagliflozin seems to possess a specific capacity to decrease arterial stiffness, which could support its cardioprotective effects observed in large clinical studies.

Trial registration Clinical trial registration: NCT03639545

Effects of SGLT2 inhibitors on systemic and tissue low-grade inflammation: The potential contribution to diabetes complications and cardiovascular disease

Chronic low-grade inflammation is a recognized key feature associated with type 2 diabetes mellitus (T2DM) and its complications. In prospective randomized trials, sodium-glucose cotransporter type 2 (SGLT2) inhibitors have demonstrated benefits related to several cardiovascular and renal risk factors, including HbA_1c, blood pressure, body weight, renal hyperfiltration, and improvement of cardiorenal outcomes. SGLT2 inhibitors may improve adipose tissue function and induce decreases in serum leptin, TNF-α and IL-6 while increasing adiponectin. While data on high-sensitivity C-reactive protein and other inflammatory markers are relatively scarce in humans, in animals, a number of reports have shown reductions in cytokine and chemokine concentrations in parallel with protective effects against progression of atherosclerotic lesions. Experimental findings also suggest that part of the renoprotective effects of SGLT2 inhibition may be related to anti-inflammatory actions at the kidney level. Underlying mechanisms to explain this anti-inflammatory effect are multiple, but may involve weight loss, and reduction in adipose tissue inflammation, slight increase in ketone bodies and diminution of uric acid levels or attenuation of oxidative stress. However, further studies in diabetes patients with specific assessment of inflammatory markers are still necessary to determine the specific contribution of the anti-inflammatory action of SGLT2 inhibitors to the reduction of cardiovascular and renal complications and mortality observed with this class of antidiabetic drugs.

Exploring novel pharmacotherapeutic applications and repurposing potential of sodium glucose CoTransporter 2 inhibitors

Sodium glucose cotransporter 2 (SGLT2) inhibitors are a relatively new class of anti-hyperglycaemic drugs with a distinctive mechanism of action focusing on renal absorption of glucose. Apart from its anti-hyperglycaemic effects, a multitude of research studies on this class have revealed that these drugs have far more versatile and comprehensive pharmacological effects than previously believed. Approximately 30% of FDA approved drugs are repurposed and used for indications other than those for which they were initially intended. Repurposing already approved drugs leads to significant reduction in pre-clinical and clinical R&D costs as well as minimizing the burden with respect to obtaining regulatory approval. SGLT2 inhibitors have been found to exhibit cardioprotective, renoprotective, anti-hyperlipidaemic, anti-atherosclerotic, anti-obesity, anti-neoplastic, hepatoprotective, and renoprotective effects in in vitro, pre-clinical, and clinical studies. The pleiotropic effects of this class have been attributed to a variety of its pharmacodynamic actions such as natriuresis, haemoconcentration, deactivation of RAAS, ketone body formation, alterations in energy homeostasis, glycosuria, lipolysis, anti-inflammatory, and anti-oxidative actions. These favourable observations encourage further research on this multifaceted class in order to effectively explore and harness its full potential and consequently lead to clinical outcomes.