EMPA-REG OUTCOME: The Cardiologist's Point of View

Cardiovascular benefits of SGLT2 inhibitors and GLP-1 receptor agonists through effects on mitochondrial function and oxidative stress

Overloaded glucose levels in several metabolic diseases such as type 2 diabetes (T2D) can lead to mitochondrial dysfunction and enhanced production of reactive oxygen species (ROS). Oxidative stress and altered mitochondrial homeostasis, particularly in the cardiovascular system, contribute to the development of chronic comorbidities of diabetes. Diabetes-associated hyperglycemia and dyslipidemia can directly damage vascular vessels and lead to coronary artery disease or stroke, and indirectly damage other organs and lead to kidney dysfunction, known as diabetic nephropathy. The new diabetes treatments include Na+-glucose cotransporter 2 inhibitors (iSGLT2) and glucagon-like 1 peptide receptor agonists (GLP-1RA), among others. The iSGLT2 are oral anti-diabetic drugs, whereas GLP-1RA are preferably administered through subcutaneous injection, even though GLP-1RA oral formulations have recently become available. Both therapies are known to improve both carbohydrate and lipid metabolism, as well as to improve cardiovascular and cardiorenal outcomes in diabetic patients. In this review, we present an overview of current knowledge on the relationship between oxidative stress, mitochondrial dysfunction, and cardiovascular therapeutic benefits of iSGLT2 and GLP-1RA. We explore the benefits, limits and common features of the treatments and remark how both are an interesting target in the prevention of obesity, T2D and cardiovascular diseases, and emphasize the lack of a complete understanding of the underlying mechanism of action.

Metformin, Empagliflozin, and Their Combination Modulate Ex-Vivo Macrophage Inflammatory Gene Expression

Type-2 Diabetes Mellitus is a complex, chronic illness characterized by persistent high blood glucose levels. Patients can be prescribed anti-diabetes drugs as single agents or in combination depending on the severity of their condition. Metformin and empagliflozin are two commonly prescribed anti-diabetes drugs which reduce hyperglycemia, however their direct effects on macrophage inflammatory responses alone or in combination are unreported. Here, we show that metformin and empagliflozin elicit proinflammatory responses on mouse bone-marrow-derived macrophages with single agent challenge, which are modulated when added in combination. In silico docking experiments suggested that empagliflozin can interact with both TLR2 and DECTIN1 receptors, and we observed that both empagliflozin and metformin increase expression of Tlr2 and Clec7a. Thus, findings from this study suggest that metformin and empagliflozin as single agents or in combination can directly modulate inflammatory gene expression in macrophages and upregulate the expression of their receptors.

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.

Evolving Evidence of Diabetic Ketoacidosis in Patients Taking Sodium-Glucose Cotransporter 2 Inhibitors

INTRODUCTION

Sodium glucose cotransporter 2 inhibitors (SGLT2i) have emerged as an important class of blood glucose-lowering medications, due to cardiovascular, metabolic, and renal benefits. However, there is a small but significant risk of diabetic ketoacidosis (DKA) associated with their use.

METHODS

A literature search was conducted in Ovid MEDLINE and Embase to July 2019 using variants on the key search terms sodium-glucose cotransporter 2, diabetic ketoacidosis, and type 2 diabetes. A broad spectrum of evidence was incorporated to facilitate a comprehensive narrative review. Further sources were identified through hand searching of reference lists.

DISCUSSION

Although cardiovascular outcome trials demonstrated mixed evidence of SGLT2i associated DKA, increasing evidence from case reports and cohort studies has identified an increased risk. SGLT2i use is associated with a ketotic state caused by an increased glucagon:insulin ratio and stimulated by factors including stress-induced hormonal changes, insufficient insulin, decreased glucose, increased ketone resorption, and hypovolemia. Atypical presentations of DKA with lower-than-expected blood glucose levels are possible with SGLT2i use, so clinical and biochemical monitoring is vital for early identification and management. DKA risk is particularly increased with precipitating factors, therefore optimization of risk factors is vital. Recommendations for perioperative and sick day management of patients taking SGLT2i have been suggested based on available evidence.

CONCLUSION

SGLT2i are an excellent class of drug in the physician's toolkit for managing type 2 diabetes. However, both clinicians and patients must be aware of the potential for DKA and the need for increased monitoring, both clinically and biochemically, when potential precipitating factors are present. In acutely unwell patients, these medications should be withheld to reduce the risk of DKA.

Effects of sodium-glucose cotransporter-2 inhibitors on the cardiovascular and renal complications of type 2 diabetes

Sodium-glucose cotransporter-2 inhibitors (SGLT-2is) have been shown to mitigate the risks of cardiovascular (CV) and renal complications in patients with type 2 diabetes (T2D) and CV risk factors or CV disease (CVD). In CV outcomes trials (CVOTs) of patients with T2D and established CVD or multiple CV risk factors, empagliflozin and canagliflozin were associated with significant reductions in the risks of major adverse CV events (MACE), hospitalization for heart failure (HF) and kidney disease progression. In the DECLARE-TIMI 58 study, in which the majority of patients did not have established CVD, dapagliflozin was associated with significant reductions in the composite end point of CV death or hospitalization for HF and was noninferior to placebo with regard to MACE; although patients had relatively good renal function, dapagliflozin also showed renal benefits similar to those seen with empagliflozin and canagliflozin. This article reviews the increased risk of CVD and renal disease in patients with T2D and discusses the potential mechanisms of the cardioprotective and renoprotective effects of SGLT-2i therapy. The observed improvements in CV and renal outcomes with SGLT-2is in CVOTs suggest a class effect in this patient population and have influenced treatment guidelines for the way add-on therapy to metformin is initiated in patients with T2D and high CV risk. The overall cardioprotective and renoprotective effects of SGLT-2is in patients with T2D and high CV risk are most likely attributable to multiple mechanisms, including cardiac, haemodynamic, metabolic, anti-inflammatory and renal effects.

Direct cardiovascular impact of SGLT2 inhibitors: mechanisms and effects

Diabetes is a global epidemic and a leading cause of death with more than 422 million patients worldwide out of whom around 392 million alone suffer from type 2 diabetes (T2D). Sodium-glucose cotransporter 2 inhibitors (SGLT2i) are novel and effective drugs in managing glycemia of T2D patients. These inhibitors gained recent clinical and basic research attention due to their clinically observed cardiovascular protective effects. Although interest in the study of various SGLT isoforms and the effect of their inhibition on cardiovascular function extends over the past 20 years, an explanation of the effects observed clinically based on available experimental data is not forthcoming. The remarkable reduction in cardiovascular (CV) mortality (38%), major CV events (14%), hospitalization for heart failure (35%), and death from any cause (32%) observed over a period of 2.6 years in patients with T2D and high CV risk in the EMPA-REG OUTCOME trial involving the SGLT2 inhibitor empagliflozin (Empa) have raised the possibility that potential novel, more specific mechanisms of SGLT2 inhibition synergize with the known modest systemic improvements, such as glycemic, body weight, diuresis, and blood pressure control. Multiple studies investigated the direct impact of SGLT2i on the cardiovascular system with limited findings and the pathophysiological role of SGLTs in the heart. The direct impact of SGLT2i on cardiac homeostasis remains controversial, especially that SGLT1 isoform is the only form expressed in the capillaries and myocardium of human and rodent hearts. The direct impact of SGLT2i on the cardiovascular system along with potential lines of future research is summarized in this review.

Cardiovascular Effects of New Oral Glucose-Lowering Agents: DPP-4 and SGLT-2 Inhibitors

Cardiovascular disease (CVD) is a major challenge in the management of type 2 diabetes mellitus. Glucose-lowering agents that reduce the risk of major cardiovascular events would be considered a major advance, as recently reported with liraglutide and semaglutide, 2 glucagon-like peptide-1 receptor agonists, and with empagliflozin and canagliflozin, 2 SGLT-2 (sodium-glucose cotransporter type 2) inhibitors, but not with DPP-4 (dipeptidyl peptidase-4) inhibitors. The present review is devoted to CV effects of new oral glucose-lowering agents. DPP-4 inhibitors (gliptins) showed some positive cardiac and vascular effects in preliminary studies, and initial data from phase 2 to 3 clinical trials suggested a reduction in major cardiovascular events. However, subsequent CV outcome trials with alogliptin, saxagliptin, and sitagliptin showed noninferiority but failed to demonstrate any superiority compared with placebo in patients with type 2 diabetes mellitus and high CV risk. An unexpected higher risk of hospitalization for heart failure was reported with saxagliptin. SGLT-2 inhibitors (gliflozins) promote glucosuria, thus reducing glucose toxicity and body weight, and enhance natriuresis, thus lowering blood pressure. Two CV outcome trials in type 2 diabetes mellitus patients mainly in secondary prevention showed remarkable positive results. Empagliflozin in EMPA-REG-OUTCOME (EMPAgliflozin Cardiovascular OUTCOME Events in Type 2 Diabetes Mellitus Patients) reduced major cardiovascular events, CV mortality, all-cause mortality, and hospitalization for heart failure. In CANVAS (Canagliflozin Cardiovascular Assessment Study), the reduction in CV mortality with canagliflozin failed to reach statistical significance despite a similar reduction in major cardiovascular events. The underlying protective mechanisms of SGLT-2 inhibitors remain unknown and both hemodynamic and metabolic explanations have been proposed. CVD-REAL studies (Comparative Effectiveness of Cardiovascular Outcomes in New Users of Sodium-Glucose Cotransporter-2 Inhibitors; with the limitation of an observational approach) suggested that these favorable results may be considered as a class effect shared by all SGLT-2 inhibitors (including dapagliflozin) and be extrapolated to a larger population of patients with type 2 diabetes mellitus in primary prevention. Ongoing CV outcome trials with other DPP-4 (linagliptin) and SGLT-2 (dapagliflozin, ertugliflozin) inhibitors should provide additional information about CV effects of both pharmacological classes.

EMPA-REG OUTCOME: The Endocrinologist's Point of View

For many years, it was widely accepted that control of plasma lipids and blood pressure could lower macrovascular risk in patients with type 2 diabetes mellitus (T2DM), whereas the benefits of lowering plasma glucose were largely limited to improvements in microvascular complications. The Empagliflozin Cardiovascular Outcome Event Trial in Type 2 Diabetes Mellitus Patients-Removing Excess Glucose (EMPA-REG OUTCOME) study demonstrated for the first time that a glucose-lowering agent, the sodium glucose cotransporter 2 (SGLT2) inhibitor empagliflozin, could reduce major adverse cardiovascular events, cardiovascular mortality, hospitalization for heart failure, and overall mortality when given in addition to standard care in patients with T2DM at high cardiovascular risk. These results were entirely unexpected and have led to much speculation regarding the potential mechanisms underlying cardiovascular benefits. In this review, the results of EMPA-REG OUTCOME are summarized and put into perspective for the endocrinologist who is treating patients with T2DM and cardiovascular disease.