EMPA-REG: Glucose excretion and lipid mobilization - not storage - saves lives

The role of empagliflozin-induced metabolic changes for cardiac function in patients with type 2 diabetes. A randomized cross-over magnetic resonance imaging study with insulin as comparator

BACKGROUND

Metabolic effects of empagliflozin treatment include lowered glucose and insulin concentrations, elevated free fatty acids and ketone bodies and have been suggested to contribute to the cardiovascular benefits of empagliflozin treatment, possibly through an improved cardiac function. We aimed to evaluate the influence of these metabolic changes on cardiac function in patients with T2D.

METHODS

In a randomized cross-over design, the SGLT2 inhibitor empagliflozin (E) was compared with insulin (I) treatment titrated to the same level of glycemic control in 17 patients with type 2 diabetes, BMI of > 28 kg/m2, C-peptide > 500 pM. Treatments lasted 5 weeks and were preceded by 3-week washouts (WO). At the end of treatments and washouts, cardiac diastolic function was determined with magnetic resonance imaging from left ventricle early peak-filling rate and left atrial passive emptying fraction (primary and key secondary endpoints); systolic function from left ventricle ejection fraction (secondary endpoint). Coupling between cardiac function and fatty acid concentrations, was studied on a separate day with a second scan after reduction of plasma fatty acids with acipimox. Data are Mean ± standard error. Between treatment difference (ΔT: E-I) and treatments effects (ΔE: E-WO or ΔI: I -WO) were evaluated using Students' t-test or Wilcoxon signed rank test as appropriate.

RESULTS

Glucose concentrations were similar, fatty acids, ketone bodies and lipid oxidation increased while insulin concentrations decreased on empagliflozin compared with insulin treatment. Cardiac diastolic and systolic function were unchanged by either treatment. Acipimox decreased fatty acids with 35% at all visits, and this led to reduced cardiac diastolic (ΔT: -51 ± 22 ml/s (p < 0.05); ΔE: -33 ± 26 ml/s (ns); ΔI: 37 ± 26 (ns, p < 0.05 vs ΔE)) and systolic function (ΔT: -3 ± 1% (p < 0.05); ΔE: -3 ± 1% (p < 0.05): ΔI: 1 ± 2 (ns, ns vs ΔE)) under chronotropic stress during empagliflozin compared to insulin treatment.

CONCLUSIONS

Despite significant metabolic differences, cardiac function did not differ on empagliflozin compared with insulin treatment. Impaired cardiac function during acipimox treatment, could suggest greater cardiac reliance on lipid metabolism for proper function during empagliflozin treatment in patients with type 2 diabetes.

TRIAL REGISTRATION

EudraCT 2017-002101-35, August 2017.

Investigating the roles of hyperglycaemia, hyperinsulinaemia and elevated free fatty acids in cardiac function in patients with type 2 diabetes via treatment with insulin compared with empagliflozin: protocol for the HyperCarD2 randomised, crossover trial

INTRODUCTION

Type 2 diabetes (T2D) is characterised by elevated plasma glucose, free fatty acid (FFA) and insulin concentrations, and this metabolic profile is linked to diabetic cardiomyopathy, a diastolic dysfunction at first and increased cardiovascular disease (CVD) risk. Shifting cardiac metabolism towards glucose utilisation has been suggested to improve cardiovascular function and CVD risk, but insulin treatment increases overall glucose oxidation and lowers lipid oxidation, without reducing CVD risk, whereas SGLT2 inhibitors (SGLT2i) increase FFA, ketone body concentrations and lipid oxidation, while decreasing insulin concentrations and CVD risk. The aim of the present study is to elucidate the importance of different metabolic profiles obtained during treatment with a SGLT2i versus insulin for myocardial function in patients with T2D.

METHODS AND ANALYSES

Randomised, crossover study, where 20 patients with T2D and body mass index>28 kg/m² receive 25 mg empagliflozin daily or NPH insulin two times per day first for 5 weeks followed by a 3-week washout before crossing over to the remaining treatment. Insulin treatment is titrated to achieve similar glycaemic control as with empagliflozin. In those randomised to insulin first, glycaemia during an initial empagliflozin run-in period prior to randomisation serves as target glucose. Metabolic and cardiac evaluation is performed before and at the end of each treatment period.The primary endpoint is change (treatment-washout) in left ventricular peak filling rate, as assessed by cardiac MRI with and without acute lowering of plasma FFAs with acipimox. Secondary and explorative endpoints are changes in left atrial passive emptying fraction, left ventricular ejection fraction, central blood volume and metabolic parameters.

ETHICS AND DISSEMINATION

This study is approved by the Danish Medicines Agency (ref. nr.: 2017061587), the Danish Data Protection Agency (ref. nr.: AHH-2017-093) and the Capital Region Ethics Committee (ref. nr.: H-17018846). The trial will be conducted in accordance with ICH-GCP guidelines and the Declaration of Helsinki and all participants will provide oral and written informed consent. Our results, regardless of outcome, will be published in relevant scientific journals and we also will seek to disseminate results through presentations at scientific meetings.

TRIAL REGISTRATION NUMBER

EudraCT: 2017-002101.

Empagliflozin Blunts Worsening Cardiac Dysfunction Associated With Reduced NLRP3 (Nucleotide-Binding Domain-Like Receptor Protein 3) Inflammasome Activation in Heart Failure

BACKGROUND

Although empagliflozin was shown to profoundly reduce cardiovascular events in diabetic patients and blunt the decline in cardiac function in nondiabetic mice with established heart failure (HF), the mechanism of action remains unknown.

METHODS AND RESULTS

We treated 2 rodent models of HF with 10 mg/kg per day empagliflozin and measured activation of the NLRP3 (nucleotide-binding domain-like receptor protein 3) inflammasome in the heart. We show for the first time that beneficial effects of empagliflozin in HF with reduced ejection fraction (HF with reduced ejection fraction [HFrEF]; n=30-34) occur in the absence of changes in circulating ketone bodies, cardiac ketone oxidation, or increased cardiac ATP production. Of note, empagliflozin attenuated activation of the NLRP3 inflammasome and expression of associated markers of sterile inflammation in hearts from mice with HFrEF, implicating reduced cardiac inflammation as a mechanism of empagliflozin that contributes to sustained function in HFrEF in the absence of diabetes mellitus. In addition, we validate that the beneficial cardiac effects of empagliflozin in HF with preserved ejection fraction (HFpEF; n=9-10) are similarly associated with reduced activation of the NLRP3 inflammasome. Lastly, the ability of empagliflozin to reduce inflammation was completely blunted by a calcium (Ca²⁺) ionophore, suggesting that empagliflozin exerts its benefit upon restoring optimal cytoplasmic Ca²⁺ levels in the heart.

CONCLUSIONS

These data provide evidence that the beneficial cardiac effects of empagliflozin are associated with reduced cardiac inflammation via blunting activation of the NLRP3 inflammasome in a Ca²⁺-dependent manner and hence may be beneficial in treating HF even in the absence of diabetes mellitus.

Dehydration and insulinopenia are necessary and sufficient for euglycemic ketoacidosis in SGLT2 inhibitor-treated rats

Sodium-glucose transport protein 2 (SGLT2) inhibitors are a class of anti-diabetic agents; however, concerns have been raised about their potential to induce euglycemic ketoacidosis and to increase both glucose production and glucagon secretion. The mechanisms behind these alterations are unknown. Here we show that the SGLT2 inhibitor (SGLT2i) dapagliflozin promotes ketoacidosis in both healthy and type 2 diabetic rats in the setting of insulinopenia through increased plasma catecholamine and corticosterone concentrations secondary to volume depletion. These derangements increase white adipose tissue (WAT) lipolysis and hepatic acetyl-CoA content, rates of hepatic glucose production, and hepatic ketogenesis. Treatment with a loop diuretic, furosemide, under insulinopenic conditions replicates the effect of dapagliflozin and causes ketoacidosis. Furthermore, the effects of SGLT2 inhibition to promote ketoacidosis are independent from hyperglucagonemia. Taken together these data in rats identify the combination of insulinopenia and dehydration as a potential target to prevent euglycemic ketoacidosis associated with SGLT2i.

The use of sodium-glucose transport protein 2 (SGLT2) inhibitors for the treatment of diabetes has been associated with euglycemic ketoacidosis and increased glucose production and glucagon secretion. Here Perry et al. show that these effects rely on both insulinopenia and dehydration, and thus suggest ways to manage the side effects associated with the use of SGLT2 inhibitors.

Empagliflozin reduces blood pressure and uric acid in patients with type 2 diabetes mellitus: a systematic review and meta-analysis

The antidiabetic effect of empagliflozin in patients with type 2 diabetes mellitus has been explored in several trials. We performed this meta-analysis determining the effects of empagliflozin on blood pressure, uric acid, estimated glomerular filtration rate, blood lipids, blood glucose, and body weight in patients with type 2 diabetes mellitus. We searched three electronic databases (Pubmed, Web of Science, and Cochrane Central) for all published articles evaluating the effects of empagliflozin on blood glucose or blood pressure in subjects with type 2 diabetes mellitus. Total 5781 patients were included in 12 randomized controlled trials with a follow-up of 28 ± 22 weeks. Empagliflozin 10 or 25 mg reduced systolic and diastolic blood pressure, uric acid, hemoglobin A1c, fasting plasma glucose, and body weight in patients with type 2 diabetes mellitus (all p < 0.001). There were no differences for changes of estimated glomerular filtration rate between empagliflozin 10 or 25 mg and placebo in these patients (all p > 0.05). In conclusion, empagliflozin reduces systolic and diastolic blood pressure, uric acid, hemoglobin A1c, fasting plasma glucose, and body weight. These data suggest the beneficial effects of empagliflozin on these cardiovascular risk factors in patients with type 2 diabetes mellitus.

MECHANISMS IN ENDOCRINOLOGY: SGLT2 inhibitors: clinical benefits by restoration of normal diurnal metabolism?

Type 2 diabetes (T2D) is associated with inhibition of autophagic and lysosomal housekeeping processes that detrimentally affect key organ functioning; a process likely to be exacerbated by conventional insulin-driven anabolic therapies. We propose that the cardio-renal benefits demonstrated with sodium-glucose cotransporter-2 inhibitor (SGLT2i) treatment in T2D partly may be explained by their ability to drive consistent, overnight periods of increased catabolism brought about by constant glucosuria. Key steps driving this catabolic mechanism include: a raised glucagon/insulin ratio initially depleting glycogen in the liver and ultimately activating gluconeogenesis utilizing circulating amino acids (AAs); a general fuel switch from glucose to free fatty acids (accompanied by a change in mitochondrial morphology from a fission to a sustained fusion state driven by a decrease in AA levels); a decrease in circulating AAs and insulin driving inhibition of mammalian target of rapamycin complex 1 (mTORC1), which enhances autophagy/lysosomal degradation of dysfunctional organelles, eventually causing a change in mitochondrial morphology from a fission to a sustained fusion state. Resumption of eating in the morning restores anabolic biogenesis of new and fully functional organelles and proteins. Restoration of diurnal metabolic rhythms and flexibility by SGLT2is may have therapeutic implications beyond those already demonstrated for the cardio-renal axis and may therefore affect other non-diabetes disease states.

How Does Empagliflozin Reduce Cardiovascular Mortality? Insights From a Mediation Analysis of the EMPA-REG OUTCOME Trial

OBJECTIVE

In the BI 10773 (Empagliflozin) Cardiovascular Outcome Event Trial in Type 2 Diabetes Mellitus Patients (EMPA-REG OUTCOME) trial involving 7,020 patients with type 2 diabetes and established cardiovascular (CV) disease, empagliflozin given in addition to standard of care reduced the risk of CV death by 38% versus placebo (hazard ratio [HR] 0.62 [95% CI 0.49, 0.77]). This exploratory mediation analysis assesses the extent to which treatment group differences in covariates during the trial contributed to CV death risk reduction with empagliflozin.

RESEARCH DESIGN AND METHODS

Effects of potential mediators, identified post hoc, on the HR for CV death with empagliflozin versus placebo were analyzed by Cox regression models, with treatment group adjusted for the baseline value of the variable and its change from baseline or updated mean (i.e., considering all prior values), each as a time-dependent covariate. HRs were compared with a model without adjustment for covariates. Multivariable analyses also were performed.

RESULTS

Changes in hematocrit and hemoglobin mediated 51.8% and 48.9%, respectively, of the effect of empagliflozin versus placebo on the risk of CV death on the basis of changes from baseline, with similar results in analyses on the basis of updated means. Smaller mediation effects (maximum 29.3%) were observed for uric acid, fasting plasma glucose, and HbA_1c. In multivariable models, which incorporated effects of empagliflozin on hematocrit, fasting glucose, uric acid, and urine albumin:creatinine ratio, the combined changes from baseline provided 85.2% mediation, whereas updated mean analyses provided 94.6% mediation of the effect of empagliflozin on CV death.

CONCLUSIONS

In this exploratory analysis from the EMPA-REG OUTCOME trial, changes in markers of plasma volume were the most important mediators of the reduction in risk of CV death with empagliflozin versus placebo.

Cardiovascular Protection by Sodium Glucose Cotransporter 2 Inhibitors: Potential Mechanisms

The mechanism of action of empagliflozin in reducing the risk of adverse cardiovascular outcomes vs placebo in patients with type 2 diabetes mellitus and a high risk of cardiovascular disease in the Empagliflozin Cardiovascular Outcome Event Trial in Type 2 Diabetes Mellitus Patients-Removing Excess Glucose (EMPA-REG OUTCOME) trial is currently unknown. An antiatherosclerotic effect is considered unlikely given the speed of the observed decrease in cardiovascular mortality. Hemodynamic effects, such as reductions in blood pressure and intravascular volume, and involving osmotic diuresis, may provide a more plausible explanation. Metabolic effects, such as cardiac fuel energetics, and hormonal effects, such as increased glucagon release, may also contribute to the results observed during EMPA-REG OUTCOME. This review discusses the main hypotheses suggested to date.

Cardiovascular Protection by Sodium Glucose Cotransporter 2 Inhibitors: Potential Mechanisms

The mechanism of action of empagliflozin in reducing the risk of adverse cardiovascular outcomes vs placebo in patients with type 2 diabetes mellitus and a high risk of cardiovascular disease in the Empagliflozin Cardiovascular Outcome Event Trial in Type 2 Diabetes Mellitus Patients-Removing Excess Glucose (EMPA-REG OUTCOME) trial is currently unknown. An antiatherosclerotic effect is considered unlikely given the speed of the observed decrease in cardiovascular mortality. Hemodynamic effects, such as reductions in blood pressure and intravascular volume, and involving osmotic diuresis, may provide a more plausible explanation. Metabolic effects, such as cardiac fuel energetics, and hormonal effects, such as increased glucagon release, may also contribute to the results observed during EMPA-REG OUTCOME. This review discusses the main hypotheses suggested to date.