SGLT2 Inhibitor-Induced Sympathoinhibition: A Novel Mechanism for Cardiorenal Protection

Heart failure and its treatment from the perspective of sympathetic nerve activity

Heart failure is the end-stage phenotype of several cardiac diseases. The number of heart failure patients is increasing in accordance with an increase in the number of elderly people. The prognosis of heart failure is poor and its 5-year death rate is comparable to that of stage III cancer. It is important to understand the essential mechanism of the worsening prognosis of heart failure and to practice effective treatment from the perspective of improving the prognosis of heart failure based on its essential mechanism. Plasma noradrenaline level is a good predictor of the survival rate of heart failure patients, and sympathetic nerve activity is augmented in patients with heart failure as evidenced by a higher noradrenaline release rate (spillover) from the sympathetic nerve endings especially in the heart and kidney. Noradrenaline release is regulated by presynaptic receptors at the sympathetic nerve endings, and the kidney affects the sympathetic nerve activity. Although the short-term reflex augmentation of sympathetic nerve activity caused by reduced cardiac function may help to improve cardiac function, long-term augmentation of sympathetic nerve activity damages the heart and deteriorates the prognosis of heart failure. Currently, drugs such as angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, β-blockers, mineralocorticoid antagonists, ivabradine, angiotensin receptor-neprilysin inhibitor, and sodium-glucose transport protein 2 inhibitors, are used for the treatment of heart failure, and had a good prognosis in large randomized, controlled clinical trials. Interestingly, the same characteristics in common of these drugs is the ability to optimize excessively augmented sympathetic nerve activity. This review discusses insights into essential mechanism of heart failure that determines the prognosis of heart failure, focusing on the interaction between sympathetic nerve activity and anti-heart failure drugs currently recommended by the 2021 guidelines of the Japanese Circulation Society and the Japanese Heart Failure Society for heart failure treatment.

Enhanced Expression and Function of Renal SGLT2 (Sodium-Glucose Cotransporter 2) in Heart Failure: Role of Renal Nerves

BACKGROUND

Recent clinical studies demonstrate that SGLT2 (sodium-glucose cotransporter 2) inhibitors ameliorate heart failure (HF). The present study was conducted to assess the expression and function of renal SGLT2 and the influence of enhanced renal sympathetic tone in HF.

METHODS

Four weeks after coronary artery ligation surgery to induce HF, surgical bilateral renal denervation (RDN) was performed in rats. Four groups of rats (Sham-operated control [Sham], Sham+RDN, HF and HF+RDN; n=6/group) were used. Immunohistochemistry and Western blot analysis were performed to evaluate the renal SGLT2 expression. One week after RDN (5 weeks after induction of HF), intravenous injection of SGLT2 inhibitor dapagliflozin were performed to assess renal excretory responses. In vitro, human embryonic kidney cells were used to investigate the fractionation of SGLT2 after norepinephrine treatment.

RESULTS

In rats with HF, (1) SGLT2 expression in the proximal tubule of the kidney was increased; (2) the response of increases in urine flow, sodium excretion, and glucose excretion to dapagliflozin were greater; and (3) RDN attenuated renal SGLT2 expression and normalized renal functional responses to dapagliflozin. In vitro, norepinephrine promoted translocation of SGLT2 to the cell membrane.

CONCLUSIONS

These results indicate that the enhanced tonic renal sympathetic nerve activation in HF increases the expression and functional activity of renal SGLT2. Potentiated trafficking of SGLT2 to cell surface in renal proximal tubules mediated by norepinephrine may contribute to this functional activation of SGLT2 in HF. These findings provide critical insight into the underlying mechanisms for the beneficial effects of SGLT2 inhibitors on HF reported in the clinical studies.

Effect of Empagliflozin on Blood Volume Redistribution in Patients With Chronic Heart Failure and Reduced Ejection Fraction: An Analysis from the Empire HF Randomized Clinical Trial

Background: Stressed blood volume (SBV) is a major determinant of systemic and pulmonary venous pressures which, in turn, determine left and right ventricular fillings and regulates cardiac output via the Frank-Starling mechanism. It is not known whether inhibition of the sodium-glucose cotransporter-2 (SGLT2) favorably affects SBV. We investigated the effect of empagliflozin on estimated stressed blood volume (eSBV) in patients with heart failure andreduced ejection fraction (HFrEF) compared to placebo. Methods: This was a post-hoc analysis of an investigator-initiated, double-blinded, placebo controlled, randomized trial. Seventy patients were assigned to empagliflozin 10 mg or matching placebo once-daily for 12 weeks. Patients underwent right heart catheterization at rest and during exercise at baseline and follow-up. The outcome was change in eSBV after 12 weeks of empagliflozin treatment over the full range of exercise, determined using a recently introduced analytical approach based on invasive hemodynamic assessment. Results: Patients with HFrEF, mean age, 57 years and mean ejection fraction 27 %, with 47 patients (71%) receiving diuretics were randomized. The effect of empagliflozin on eSBV over the full range of exercise loads showed a statistically significant reduction compared with placebo (-198.4 mL, 95%CI: -317.4; -79.3, p=0.001), a 9% decrease. The decrease in eSBV by empagliflozin was significantly correlated with the decrease in PCWP ((R= ̶ 0.33, p<0.0001). The effect of empagliflozin was consistent across subgroup analysis. Conclusions: Empagliflozin treatment significantly reduced stressed blood volume compared with placebo after 12 weeks of treatment in patients with stable chronic HFrEF during sub maximal exercise. Registration: URL: https://www.clinicaltrials.gov, Unique identifier: NCT03198585.

The diuretic effects of SGLT2 inhibitors: A comprehensive review of their specificities and their role in renal protection

Sodium-glucose cotransporter type 2 inhibitors (SGLT2is) are new oral glucose-lowering agents that provide cardiovascular and renal protection in both patients with and without type 2 diabetes. Because of their unique mechanism of action, increased glucosuria is associated with osmotic diuresis and some natriuresis, yet the latter seems mostly transient. The potential role of the diuretic effect in overall cardiovascular and renal protection by SGLT2is remains a matter of debate. Precise evaluation of the diuretic effect is not so easy and most studies relied upon indirect estimations that led to divergent results, presumably also explained by different study designs and population characteristics. Everybody agrees upon the fact that SGLT2is are different from other classical diuretics (thiazides and loop diuretics) as they present some favourable properties, i.e. reduced sympathetic activity, preserved potassium balance, lower risk of acute renal injury, decrease of serum uric acid level. The potential role of the diuretic effect of SGLT2is on renal outcomes is still unclear, yet their ability to reduce albuminuria and dampen the risk of heart failure may contribute to improve renal prognosis besides other complex underlying mechanisms. In this comprehensive review we first critically analyse the results obtained with indirect methods that assess a diuretic effect of SGLT2is, second we describe the specificities of the diuretic activity of SGLT2is compared with other classical diuretics, and third we discuss the potential mechanisms by which the diuretic effect of SGLT2is could contribute to the improvement of renal outcomes consistently reported with this innovative amazing pharmacological class.

A registry-based randomised trial comparing an SGLT2 inhibitor and metformin as standard treatment of early stage type 2 diabetes (SMARTEST): Rationale, design and protocol

AIM

SGLT2 inhibitors have been shown to reduce cardiovascular and renal complications in type 2 diabetes (T2D) patients at high cardiovascular risk. Metformin is currently widely used as initial monotherapy in T2D but lacks convincing data to show that it reduces risk of complications. We aim to compare the SGLT2 inhibitor dapagliflozin and metformin as first-line T2D medication with regard to development of complications in a registry-based randomised controlled trial.

METHODS

The SGLT2 inhibitor or metformin as standard treatment of early stage type 2 diabetes (SMARTEST) trial will enrol 4300 subjects at 30-40 study sites in Sweden who will be randomised 1:1 to either metformin or dapagliflozin. Participants must have T2D duration <4 years, no prior cardiovascular disease, and be either drug-naïve or on monotherapy for T2D.

RESULTS

The primary endpoint is a composite of all-cause death, major adverse cardiovascular events and occurrence or progression of microvascular complications (retinopathy, nephropathy, diabetic foot lesions). Secondary endpoints include individual components of the primary endpoint, start of insulin therapy, risk factor biomarkers, patient-reported outcome measures, and cost-effectiveness analysis. Outcomes will primarily be assessed using nationwide healthcare registries.

CONCLUSIONS

The SMARTEST trial will investigate whether dapagliflozin is superior to metformin in preventing complications in early stage T2D. (Clinicaltrials.gov identifier NCT03982381, EudraCT 2019-001046-17).

Bexagliflozin for type 2 diabetes: an overview of the data

Introduction: Sodium-glucose cotransporter-2 (SGLT2) inhibitors are a relatively novel glucose-lowering drugs (GLDs) which additionally promote weight loss and blood pressure reduction among other beneficial effects.Areas covered: This review reflects on the extra-glycemic effects of SGLT2 inhibitors and their impact on important clinical endpoints, and provides an overview of data relating to a newer member of the SGLT2 inhibitor class, bexagliflozin.Expert opinion: SGLT2 inhibitors, while consolidating glycemic control as adjunctive therapy, indisputably affect cardio-renal benefits in the T2D population which is prevalently afflicted by heightened cardiovascular risk and a disproportionately increased incidence of unfavorable cardiovascular and renal outcomes. The data from landmark trials demonstrate that beneficial effects of SGLT2 inhibitors extend to non-diabetic patients with chronic kidney disease (CKD) and/or heart failure with reduced ejection fraction (HFrEF). Preliminary findings from the BEST trial suggest that Bexagliflozin's effects reflect those of other licensed drugs in its class. Bexagliflozin has also been shown to be safe and effective in patients with diabetes and CKD stage 3b. If and when approved, it presents physicians with the prospect of an additional therapeutic option in managing patients with type 2 diabetes mellitus (T2D), and conceivably also, nondiabetic patients with established CKD and/or HFrEF.

Could Sodium/Glucose Co-Transporter-2 Inhibitors Have Antiarrhythmic Potential in Atrial Fibrillation? Literature Review and Future Considerations

The global burden of atrial fibrillation (AF) is constantly increasing, necessitating novel and effective therapeutic options. Sodium glucose co-transporter 2 (SGLT2) inhibitors have been introduced in clinical practice as glucose-lowering medications. However, they have recently gained prominence for their potential to exert substantial cardiorenal protection and are being evaluated in large clinical trials including patients with type 2 diabetes and normoglycemic adults. In this review we present up-to-date available evidence in a pathophysiology-directed manner from cell to bedside. Preclinical and clinical data regarding a conceivable antiarrhythmic effect of SGLT2 inhibitors are beginning to accumulate. Herein we comprehensively present data that explore the potential pathophysiological link between SGLT2 inhibitors and AF. With regard to clinical data, no randomized controlled trials evaluating SGLT2 inhibitors effects on AF as a pre-specified endpoint are available. However, data from randomized controlled trial post-hoc analysis as well as observational studies point to a possible beneficial effect of SGLT2 inhibitors on AF. Meta-analyses addressing this question report inconsistent results and the real magnitude of AF prevention by SGLT2 inhibition remains unclear. Still, while (i) pathophysiologic mechanisms involved in AF might be favorably affected by SGLT2 inhibitors and (ii) emerging, yet inconsistent, clinical data imply that SGLT2 inhibitor-mediated cardiorenal protection could also exert antiarrhythmic effects, the argument of whether these novel drugs will reduce AF burden is unsettled and mandates appropriately designed and adequately sized randomized controlled studies.

Sympatholytic Mechanisms for the Beneficial Cardiovascular Effects of SGLT2 Inhibitors: A Research Hypothesis for Dapagliflozin's Effects in the Adrenal Gland

Heart failure (HF) remains the leading cause of morbidity and death in the western world, and new therapeutic modalities are urgently needed to improve the lifespan and quality of life of HF patients. The sodium-glucose co-transporter-2 (SGLT2) inhibitors, originally developed and mainly indicated for diabetes mellitus treatment, have been increasingly shown to ameliorate heart disease, and specifically HF, in humans, regardless of diabetes co-existence. Indeed, dapagliflozin has been reported to reduce cardiovascular mortality and hospitalizations in patients with HF and reduced ejection fraction (HFrEF). This SGLT2 inhibitor demonstrates these benefits also in non-diabetic subjects, indicating that dapagliflozin's efficacy in HF is independent of blood glucose control. Evidence for the effectiveness of various SGLT2 inhibitors in providing cardiovascular benefits irrespective of their effects on blood glucose regulation have spurred the use of these agents in HFrEF treatment and resulted in FDA approvals for cardiovascular indications. The obvious question arising from all these studies is, of course, which molecular/pharmacological mechanisms underlie these cardiovascular benefits of the drugs in diabetics and non-diabetics alike. The fact that SGLT2 is not significantly expressed in cardiac myocytes (SGLT1 appears to be the dominant isoform) adds even greater perplexity to this answer. A variety of mechanisms have been proposed over the past few years and tested in cell and animal models and prominent among those is the potential for sympatholysis, i.e., reduction in sympathetic nervous system activity. The latter is known to be high in HF patients, contributing significantly to the morbidity and mortality of the disease. The present minireview first summarizes the current evidence in the literature supporting the notion that SGLT2 inhibitors, such as dapagliflozin and empagliflozin, exert sympatholysis, and also outlines the main putative underlying mechanisms for these sympatholytic effects. Then, we propose a novel hypothesis, centered on the adrenal medulla, for the sympatholytic effects specifically of dapagliflozin. Adrenal medulla is responsible for the production and secretion of almost the entire amount of circulating epinephrine and of a significant percentage of circulating norepinephrine in the human body. If proven true experimentally, this hypothesis, along with other emerging experimental evidence for sympatholytic effects in neurons, will shed new light on the pharmacological effects that mediate the cardiovascular benefits of SGLT2 inhibitor drugs, independently of their blood glucose-lowering effects.

Relationship Between HbA1c Level and Effectiveness of SGLT2 Inhibitors in Decompensated Heart Failure Patients with Type 2 Diabetes Mellitus

The DAPA-HF trial demonstrated that sodium-glucose cotransporter 2 inhibitors (SGLT2i) reduced worsening heart failure (HF) events in chronic HF patients with or without type 2 diabetic mellitus (T2DM). However, it remains unclear whether the effectiveness of SGLT2i is also observed in patients with decompensated HF irrespective of HbA1c level. Eighty-one T2DM patients hospitalized due to decompensated HF were enrolled and divided into 2 groups according to their HbA1c levels (group H, HbA1c 6.9-13.0%, n = 41; group L, HbA1c < 6.9%, n = 40). After the initial management of HF, one of the SGLT2i (canagliflozin 100 mg/day or dapagliflozin 5 mg/day or empagliflozin 10 mg/day) was non-randomly administered, and clinical parameters associating with HF and T2DM were followed for 7 days. No symptomatic hypoglycemia was observed in any patient. In both groups, urine glucose excretion was increased significantly after the administration of SGLT2i. However, its amount was greater in group H than group L. Urine volume was increased significantly at day 1 in both groups. Urine volume returned to the baseline after one week in group L. In contrast, the increase in urine volume persisted at least for one week in group H. Of note, a decrease in B-type natriuretic peptide levels after the initiation of SGLT2i was observed in both groups similarly despite differences in urine output and excretion of urine glucose. In conclusion, SGLT2i can improve decompensated HF in patients with T2DM irrespective of the HbA1c level.

Cardio-Renal Benefits of SGLT2 Inhibitors in Heart Failure with Reduced Ejection Fraction: Mechanisms and Clinical Evidence

The heart and the kidneys are closely interconnected, and disease in one organ system can lead to disease in the other. This interdependence is illustrated in heart failure with reduced ejection fraction (HFrEF), where worsening heart failure can lead to renal dysfunction and vice versa. Further complicating this situation is the fact that drugs that serve as guideline directed medical therapy (GDMT) for HFrEF can affect renal function. Sodium glucose co-transporter 2 (SGLT2) inhibitors are a new class of medication with an evolving role in heart failure (HF) and chronic kidney disease (CKD). Initially found to have benefits in diabetics, new research established potential cardiovascular and renal benefits in patients with HF independent of their diabetic status and in populations with CKD. This has been established by landmark trials such as EMPEROR-Reduced, EMPA-TROPISM, CREDENCE, DAPA-CKD, DAPA-HF, and DEFINE-HF. Multiple mechanisms responsible for these benefits have been suggested by clinical and non-clinical studies, and involve cardiac and renal energetic efficiency, cardiac remodeling, preservation of renal function, immunomodulation, changes in hematocrit, and control of risk factors. As such, SGLT2 inhibitors have tremendous potential to improve outcomes in populations with HF and CKD. The purpose of this review is to discuss the current evidence and underlying mechanisms for the cardio-renal benefits of SGLT2 inhibitors in patients with HFrEF.

Mechanisms and Models in Heart Failure: A Translational Approach

Despite multiple attempts to develop a unifying hypothesis that explains the pathophysiology of heart failure with a reduced ejection fraction (HFrEF), no single conceptual model has withstood the test of time. In the present review, we discuss how the results of recent successful phase III clinical development programs in HFrEF are built upon existing conceptual models for drug development. We will also discuss where recent successes in clinical trials do not fit existing models to identify areas where further refinement of current paradigms may be needed. To provide the necessary structure for this review, we will begin with a brief overview of the pathophysiology of HFrEF, followed by an overview of the current conceptual models for HFrEF, and end with an analysis of the scientific rationale and clinical development programs for 4 new therapeutic classes of drugs that have improved clinical outcomes in HFrEF. The 4 new therapeutic classes discussed are ARNIs, SGLT2 (sodium-glucose cotransporter 2) inhibitors, soluble guanylate cyclase stimulators, and myosin activators. With the exception of SGLT2 inhibitors, each of these therapeutic advances was informed by the insights provided by existing conceptual models of heart failure. Although the quest to determine the mechanism of action of SGLT2 inhibitors is ongoing, this therapeutic class of drugs may represent the most important advance in cardiovascular therapeutics of recent decades and may lead to rethinking or expanding our current conceptual models for HFrEF.

Implications of ADAM17 activation for hyperglycaemia, obesity and type 2 diabetes

In this review, we focus specifically on the role that the metalloproteinase, A Disintegrin and Metalloproteinase 17 [ADAM17] plays in the development and progression of the metabolic syndrome. There is a well-recognised link between the ADAM17 substrate tumour necrosis factor α (TNF-α) and obesity, inflammation and diabetes. In addition, knocking out ADAM17 in mice leads to an extremely lean phenotype. Importantly, ADAM17-deficient mice exhibit one of the most pronounced examples of hypermetabolism in rodents to date. It is vital to further understand the mechanistic role that ADAM17 plays in the metabolic syndrome. Such studies will demonstrate that ADAM17 is a valuable therapeutic target to treat obesity and diabetes.

Sodium-Glucose Cotransporter 2 Inhibitors in Patients with Non-Diabetic Chronic Kidney Disease

BACKGROUND

Sodium-glucose cotransporter 2 (SGLT2) inhibitors can reduce cardiovascular morbidity and mortality in patients with type 2 diabetes. Furthermore, recent clinical studies have revealed that SGLT2 inhibitors decrease the risk of renal function impairment in patients with type 2 diabetes. However, the effects of SGLT2 inhibitors on non-diabetic chronic kidney disease (CKD) remains unclear. Regarding long-term clinical outcomes, the Dapagliflozin and Prevention of Adverse Outcomes in Heart Failure (DAPA-HF) trial explicitly showed improvements in cardiovascular outcomes in patients presenting with heart failure, even in the absence of diabetes. The reduction in heart failure in patients without diabetes was confirmed following empagliflozin administration in the EMPagliflozin outcomE tRial in patients with chrOnic heart failure with Reduced ejection fraction (EMPEROR-Reduced) trial. A recent systematic review and meta-analysis of DAPA-HF and EMPEROR-Reduced showed improvements in the composite renal endpoint regardless of the presence of diabetes or baseline estimated glomerular filtration rate. The Dapagliflozin and Prevention of Adverse outcomes in Chronic Kidney Disease (DAPA-CKD) trial evaluated patients with CKD with or without type 2 diabetes, irrespective of whether SGLT2 inhibitor dapagliflozin was added for renin-angiotensin system blockade as background renoprotective therapy. In this trial, dapagliflozin reduced the hazard ratio for a composite renal and cardiovascular death endpoint in patients with CKD attributed to various causes, with or without type 2 diabetes.

SGLT2-inhibitors; more than just glycosuria and diuresis

Heart failure (HF) continues to be a serious public health challenge despite significant advancements in therapeutics and is often complicated by multiple other comorbidities. Of particular concern is type 2 diabetes mellitus (T2DM) which not only amplifies the risk, but also limits the treatment options available to patients. The sodium-glucose linked cotransporter subtype 2 (SGLT2)-inhibitor class, which was initially developed as a treatment for T2DM, has shown great promise in reducing cardiovascular risk, particularly around HF outcomes - regardless of diabetes status.There are ongoing efforts to elucidate the true mechanism of action of this novel drug class. Its primary mechanism of inducing glycosuria and diuresis from receptor blockade in the renal nephron seems unlikely to be responsible for the rapid and striking benefits seen in clinical trials. Early mechanistic work around conventional therapeutic targets seem to be inconclusive. There are some emerging theories around its effect on myocardial energetics and calcium balance as well as on renal physiology. In this review, we discuss some of the cutting-edge hypotheses and concepts currently being explored around this drug class in an attempt better understand the molecular mechanics of this novel agent.

A kidney perspective on the mechanism of action of sodium glucose co-transporter 2 inhibitors

Sodium glucose co-transporter (SGLT) 2 inhibitors reduce the risk of kidney failure in patients with and without type 2 diabetes (T2D). Although the precise underlying mechanisms for these nephroprotective effects are incompletely understood, various hypotheses have been proposed including reductions in intraglomerular pressure through restoration of tubuloglomerular feedback, blood pressure reduction and favorable effects on vascular function, reduction in tubular workload and hypoxia, and metabolic effects resulting in increased autophagy. Here, we review these mechanisms, which may also explain the beneficial effects of SGLT2 inhibitors on kidney function in patients without T2D.

Impact of SGLT-2 Inhibition on Cardiometabolic Abnormalities in a Rat Model of Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in reproductive-age women. PCOS is characterized by hyperandrogenism and ovulatory dysfunction. Women with PCOS have a high prevalence of obesity, insulin resistance (IR), increased blood pressure (BP), and activation of the renin angiotensin system (RAS). Effective evidence-based therapeutics to ameliorate the cardiometabolic complications in PCOS are lacking. The sodium-glucose cotransporter-2 (SGLT2) inhibitor Empagliflozin (EMPA) reduces BP and hyperglycemia in type 2 diabetes mellitus. We hypothesized that hyperandrogenemia upregulates renal SGLT2 expression and that EMPA ameliorates cardiometabolic complications in a hyperandrogenemic PCOS model. Four-week-old female Sprague Dawley rats were treated with dihydrotestosterone (DHT) for 90 days, and EMPA was co-administered for the last three weeks. DHT upregulated renal SGLT2, SGLT4, and GLUT2, but downregulated SGLT3 mRNA expression. EMPA decreased DHT-mediated increases in fat mass, plasma leptin, and BP, but failed to decrease plasma insulin, HbA1c, or albuminuria. EMPA decreased DHT-mediated increase in renal angiotensin converting enzyme (ACE), angiotensin converting enzyme 2 (ACE2), and angiotensin II type 1 receptor (AGT1R) mRNA and protein expression. In summary, SGLT2 inhibition proved beneficial in adiposity and BP reduction in a hyperandrogenemic PCOS model; however, additional therapies may be needed to improve IR and renal injury.

Inhibition of the sodium-glucose co-transporter SGLT2 by canagliflozin ameliorates diet-induced obesity by increasing intra-adipose sympathetic innervation

BACKGROUND AND PURPOSE

Inhibition of the sodium-glucose cotransporter 2 (SGLT2) induces hypoglycaemia by increasing urinary glucose excretion and increasing the use of fat. However, the underlying mechanism is poorly understood. This study was aimed to determine the effects of canagliflozin, a selective SGLT2 inhibitor, on diet-induced obesity and the underlying mechanism(s).

EXPERIMENTAL APPROACH

Adult C57BL/6J male mice were fed with a standard chow diet or high-fat diet supplemented with vehicle or canagliflozin. Whole body energy expenditure was monitored by metabolic cages, noradrenaline levels were measured by HPLC, glucose uptake was measured by PET/CT, and mRNA and protein expression were measured by RT-PCR and western blotting analysis.

KEY RESULTS

Mice treated with canagliflozin were resistant to high-fat diet-induced obesity and its metabolic consequences. Canagliflozin treatment decreased fat mass and increased energy expenditure via increasing thermogenesis and lipolysis in adipose tissue. Mechanistically, SGLT2 inhibition by canagliflozin elevated adipose sympathetic innervation and fat mobilization via a β₃ -adrenoceptor-cAMP-PKA signalling pathway. Finally, we showed that canagliflozin improved insulin resistance and hepatic steatosis in mice fed with a high-fat diet.

CONCLUSIONS AND IMPLICATIONS

Chronic inhibition of SGLT2 increased energy consumption by increasing intra-adipose sympathetic innervation to counteract diet-induced obesity. The present study reveals a new therapeutic function for SGLT2 inhibitors in regulating energy homeostasis.

Renal protection: a leading mechanism for cardiovascular benefit in patients treated with SGLT2 inhibitors

Initially developed as glucose-lowering drugs, sodium-glucose co-transporter type 2 inhibitors (SGLT2i) have demonstrated to be effective agents for the risk reduction of cardiovascular (CV) events in patients with type 2 diabetes mellitus (T2DM). Subsequently, data has emerged showing a significant CV benefit in patients treated with SGLT2i regardless of diabetes status. Renal protection has been initially evaluated in CV randomized trials only as secondary endpoints; nonetheless, the positive results gained have rapidly led to the evaluation of nephroprotection as primary outcome in the CREDENCE trial. Different renal and vascular mechanisms can account for the CV and renal benefits enlightened in recent literature. As clinical guidelines rapidly evolve and the role of SGLT2i appears to become pivotal for CV, T2DM, and kidney disease management, in this review, we analyze the renal effects of SGLT2, the benefits derived from its inhibition, and how this may result in the multiple CV and renal benefits evidenced in recent clinical trials.

Effects of SGLT2 Inhibitors on Kidney and Cardiovascular Function

SGLT2 inhibitors are antihyperglycemic drugs that protect kidneys and the heart of patients with or without type 2 diabetes and preserved or reduced kidney function from failing. The involved protective mechanisms include blood glucose-dependent and -independent mechanisms: SGLT2 inhibitors prevent both hyper- and hypoglycemia, with expectedly little net effect on HbA1C. Metabolic adaptations to induced urinary glucose loss include reduced fat mass and more ketone bodies as additional fuel. SGLT2 inhibitors lower glomerular capillary hypertension and hyperfiltration, thereby reducing the physical stress on the filtration barrier, albuminuria, and the oxygen demand for tubular reabsorption. This improves cortical oxygenation, which, together with lesser tubular gluco-toxicity, may preserve tubular function and glomerular filtration rate in the long term. SGLT2 inhibitors may mimic systemic hypoxia and stimulate erythropoiesis, which improves organ oxygen delivery. SGLT2 inhibitors are proximal tubule and osmotic diuretics that reduce volume retention and blood pressure and preserve heart function, potentially in part by overcoming the resistance to diuretics and atrial-natriuretic-peptide and inhibiting Na-H exchangers and sympathetic tone.

Blood Pressure Effects of Canagliflozin and Clinical Outcomes in Type 2 Diabetes and Chronic Kidney Disease: Insights From the CREDENCE Trial

BACKGROUND

People with type 2 diabetes and chronic kidney disease experience a high burden of hypertension, but the magnitude and consistency of blood pressure (BP) lowering with canagliflozin in this population are uncertain. Whether the effects of canagliflozin on kidney and cardiovascular outcomes vary by baseline BP or BP-lowering therapy is also unknown.

METHODS

The CREDENCE trial (Canagliflozin and Renal Events in Diabetes with Established Nephropathy Clinical Evaluation) randomized people with type 2 diabetes and chronic kidney disease to canagliflozin or placebo. In a post hoc analysis, we investigated the effect of canagliflozin on systolic BP across subgroups defined by baseline systolic BP, number of BP-lowering drug classes, and history of apparent treatment-resistant hypertension (BP ≥130/80 mm Hg while receiving ≥3 classes of BP-lowering drugs, including a diuretic). We also assessed whether effects on clinical outcomes differed across these subgroups.

RESULTS

The trial included 4401 participants, of whom 3361 (76.4%) had baseline systolic BP ≥130 mm Hg, and 1371 (31.2%) had resistant hypertension. By week 3, canagliflozin reduced systolic BP by 3.50 mm Hg (95% CI, -4.27 to -2.72), an effect maintained over the duration of the trial, with similar reductions across BP and BP-lowering therapy subgroups (all P interaction ≥0.05). Canagliflozin also reduced the need for initiation of additional BP-lowering agents during the trial (hazard ratio, 0.68 [95% CI, 0.61-0.75]). The effect of canagliflozin on kidney failure, doubling of serum creatinine, or death caused by kidney or cardiovascular disease (hazard ratio, 0.70 [95% CI, 0.59-0.82]) was consistent across BP and BP-lowering therapy subgroups (all P interaction ≥0.35), as were effects on other key kidney, cardiovascular, and safety outcomes.

CONCLUSIONS

In people with type 2 diabetes and chronic kidney disease, canagliflozin lowers systolic BP across all BP-defined subgroups and reduces the need for additional BP-lowering agents. These findings support use of canagliflozin for end-organ protection and as an adjunct BP-lowering therapy in people with chronic kidney disease. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02065791.

Natriuretic Effect of Two Weeks of Dapagliflozin Treatment in Patients With Type 2 Diabetes and Preserved Kidney Function During Standardized Sodium Intake: Results of the DAPASALT Trial

OBJECTIVE

Sodium-glucose cotransporter 2 (SGLT2) inhibitors reduce the risk for heart failure hospitalization potentially by inducing sodium excretion, osmotic diuresis, and plasma volume contraction. Few studies have investigated this hypothesis, but none have assessed cumulative sodium excretion with SGLT2 inhibition during standardized sodium intake in patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

The DAPASALT trial was a mechanistic, nonrandomized, open-label study in patients with type 2 diabetes with preserved kidney function on a controlled standardized sodium diet (150 mmol/day). It evaluated the effects of dapagliflozin on sodium excretion, 24-h blood pressure, and extracellular, intracellular, and plasma volumes at the start of treatment (ST) (days 2-4), end of treatment (ET) (days 12-14), and follow-up (FU) (days 15-18).

RESULTS

Fourteen patients were included in the efficacy analysis. Mean (SD) baseline sodium excretion (150 [32] mmol/24-h) did not significantly change during treatment (change at ST: -7.0 mmol/24-h [95% CI -22.4, 8.4]; change at ET: 2.1 mmol/24-h [-28.8, 33.0]). Mean baseline 24-h systolic blood pressure was 128 (10) mmHg and significantly reduced at ST (-6.1 mmHg [-9.1, -3.1]; P < 0.001) and ET (-7.2 mmHg [-10.0, -4.3]; P < 0.001). Dapagliflozin did not significantly alter plasma volume or intracellular volume, while extracellular volume changed at ST (-0.7 L [-1.3, -0.1]; P = 0.02). As expected, 24-h urinary glucose excretion significantly increased during dapagliflozin treatment and reversed during FU.

CONCLUSIONS

During standardized sodium intake, dapagliflozin reduced blood pressure without clear changes in urinary sodium excretion, suggesting that factors other than natriuresis and volume changes may contribute to the blood pressure-lowering effects.

Nitric oxide signalling in kidney regulation and cardiometabolic health

The prevalence of cardiovascular and metabolic disease coupled with kidney dysfunction is increasing worldwide. This triad of disorders is associated with considerable morbidity and mortality as well as a substantial economic burden. Further understanding of the underlying pathophysiological mechanisms is important to develop novel preventive or therapeutic approaches. Among the proposed mechanisms, compromised nitric oxide (NO) bioactivity associated with oxidative stress is considered to be important. NO is a short-lived diatomic signalling molecule that exerts numerous effects on the kidneys, heart and vasculature as well as on peripheral metabolically active organs. The enzymatic L-arginine-dependent NO synthase (NOS) pathway is classically viewed as the main source of endogenous NO formation. However, the function of the NOS system is often compromised in various pathologies including kidney, cardiovascular and metabolic diseases. An alternative pathway, the nitrate-nitrite-NO pathway, enables endogenous or dietary-derived inorganic nitrate and nitrite to be recycled via serial reduction to form bioactive nitrogen species, including NO, independent of the NOS system. Signalling via these nitrogen species is linked with cGMP-dependent and independent mechanisms. Novel approaches to restoring NO homeostasis during NOS deficiency and oxidative stress have potential therapeutic applications in kidney, cardiovascular and metabolic disorders.

Lower cardiorenal risk with sodium-glucose cotransporter-2 inhibitors versus dipeptidyl peptidase-4 inhibitors in patients with type 2 diabetes without cardiovascular and renal diseases: A large multinational observational study

AIMS

We compared the new use of sodium-glucose cotransporter-2 inhibitor (SGLT2i) versus dipeptidyl peptidase-4 inhibitor (DPP4i) and the risk of cardiorenal disease, heart failure (HF) or chronic kidney disease (CKD), in patients with type 2 diabetes without a history of prevalent cardiovascular and renal disease, defined as cardiovascular and renal disease (CVRD) free, managed in routine clinical practice.

MATERIALS AND METHODS

In this observational cohort study, patients were identified from electronic health records from England, Germany, Japan, Norway, South Korea and Sweden, during 2012-2018. In total, 1 006 577 CVRD-free new users of SGLT2i or DPP4i were propensity score matched 1:1. Unadjusted Cox regression was used to estimate hazard ratios (HRs) for outcomes: cardiorenal disease, HF, CKD, stroke, myocardial infarction (MI), cardiovascular and all-cause mortality.

RESULTS

Baseline characteristics were well balanced between the treatment groups (n = 105 130 in each group) with total follow-up of 187 955 patient years. Patients had a mean age of 56 years, 43% were women and they were indexed between 2013 and 2018. The most commonly used agents were dapagliflozin (91.7% of exposure time) and sitagliptin/linagliptin (55.0%), in the SGLT2i and DPP4i, groups, respectively. SGLT2i was associated with lower risk of cardiorenal disease, HF, CKD, all-cause and cardiovascular mortality; HR (95% confidence interval), 0.56 (0.42-0.74), 0.71 (0.59-0.86), 0.44 (0.28-0.69), 0.67 (0.59-0.77), and 0.61 (0.44-0.85), respectively. No differences were observed for stroke [0.87 (0.69-1.09)] and MI [0.94 (0.80-1.11)].

CONCLUSION

In this multinational observational study, SGLT2i was associated with a lower risk of HF and CKD versus DPP4i in patients with type 2 diabetes otherwise free from both cardiovascular and renal disease.

Role of peripheral 5-HT5A receptors in 5-HT-induced cardiac sympatho-inhibition in type 1 diabetic rats

5-HT inhibits cardiac sympathetic neurotransmission in normoglycaemic rats, via 5-HT1B, 5-HT1Dand 5-HT5Areceptor activation. Since type 1 diabetes impairs the cardiac sympathetic innervation leading to cardiopathies, this study aimed to investigate whether the serotonergic influence on cardiac noradrenergic control is altered in type 1 diabetic rats. Diabetes was induced in male Wistar rats by streptozotocin (50 mg/kg, i.p.). Four weeks later, the rats were anaesthetized, pithed and prepared for producing tachycardic responses by electrical preganglionic stimulation (C7-T1) of the cardioaccelerator sympathetic outflow or i.v. noradrenaline bolus injections. Immunohistochemistry was performed to study 5-HT1B, 5-HT1Dand 5-HT5Areceptor expression in the stellate ganglion from normoglycaemic and diabetic rats. In the diabetic group, i) i.v. continuous infusions of 5-HT induced a cardiac sympatho-inhibition that was mimicked by the 5-HT1/5Aagonist 5-carboxamidotryptamine (without modifying noradrenaline-induced tachycardia), but not by the agonists indorenate (5-HT1A), CP 93,129 (5-HT1B), PNU 142633 (5-HT1D), or LY344864 (5-HT1F); ii) SB 699551 (5-HT5Aantagonist; i.v.) completely reversed 5-CT-induced cardiac sympatho-inhibition; and iii) 5-HT5Areceptors were more expressed in the stellate ganglion compared to normoglycaemic rats. These results show the prominent role of the peripheral 5-HT5Areceptors prejunctionally inhibiting the cardiac sympathetic drive in type 1 diabetic rats.

Effects of Canagliflozin in Patients with Baseline eGFR <30 ml/min per 1.73 m2: Subgroup Analysis of the Randomized CREDENCE Trial

BACKGROUND AND OBJECTIVES

The Canagliflozin and Renal Events in Diabetes with Established Nephropathy Clinical Evaluation (CREDENCE) trial demonstrated that the sodium glucose cotransporter 2 (SGLT2) inhibitor canagliflozin reduced the risk of kidney failure and cardiovascular events in participants with type 2 diabetes mellitus and CKD. Little is known about the use of SGLT2 inhibitors in patients with eGFR <30 ml/min per 1.73 m². The participants in the CREDENCE study had type 2 diabetes mellitus, a urinary albumin-creatinine ratio >300-5000 mg/g, and an eGFR of 30 to <90 ml/min per 1.73 m² at screening. This post hoc analysis evaluated participants with eGFR <30 ml/min per 1.73 m² at randomization.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Effects of eGFR slope through week 130 were analyzed using a piecewise, linear, mixed-effects model. Efficacy was analyzed in the intention-to-treat population, on the basis of Cox proportional hazard models, and safety was analyzed in the on-treatment population. At randomization (an average of 29 days after screening), 174 of 4401 (4%) participants had an eGFR <30 ml/min per 1.73 m² (mean [SD] eGFR, 26 [3] ml/min per 1.73 m²).

RESULTS

From weeks 3 to 130, there was a 66% difference in the mean rate of eGFR decline with canagliflozin versus placebo (mean slopes, -1.30 versus -3.83 ml/min per 1.73 m² per year; difference, -2.54 ml/min per 1.73 m² per year; 95% confidence interval [CI], 0.90 to 4.17). Effects of canagliflozin on kidney, cardiovascular, and mortality outcomes were consistent for those with eGFR <30 and ≥30 ml/min per 1.73 m² (all P interaction >0.20). The estimate for kidney failure in participants with eGFR <30 ml/min per 1.73 m² (hazard ratio, 0.67; 95% CI, 0.35 to 1.27) was similar to those with eGFR ≥30 ml/min per 1.73 m² (hazard ratio, 0.70; 95% CI, 0.54 to 0.91; P interaction=0.80). There was no imbalance in the rate of kidney-related adverse events or AKI associated with canagliflozin between participants with eGFR <30 and ≥30 ml/min per 1.73 m² (all P interaction >0.12).

CONCLUSIONS

This post hoc analysis suggests canagliflozin slowed progression of kidney disease, without increasing AKI, even in participants with eGFR <30 ml/min per 1.73 m².

SGLT2 Inhibitor-Induced Sympathoexcitation in White Adipose Tissue: A Novel Mechanism for Beiging

Recent preclinical data show that sodium glucose cotransporter 2 (SGLT2) inhibitors are able to reduce weight gain and induce beiging in white adipose tissue (WAT). We have previously shown that in neurogenic hypertensive Schlager (BPH/2J) mice, treatment with the SGLT2 inhibitor, Dapagliflozin, reduced blood pressure and prevented weight gain. Here we show that chemical sympathetic denervation achieved by systemic administration of 6-hydroxy-dopamine (6-OHDA) reduces body weight and the heightened sympathetic nervous system (SNS) innervation in WAT. Furthermore, we demonstrate that 2 weeks of Dapagliflozin treatment increases SNS innervation in WAT of hypertensive mice. This increase is accompanied by a non-significant elevation in mRNA levels of the Ucp1 and Pgc-1α genes, which are markers of beiging. No significant difference in the mRNA levels of the inflammatory mediators Il-6 and Tnf-α were detected in WAT of Dapagliflozin treated mice. These findings suggest that SGLT-2 inhibitor-associated prevention of weight gain may be mediated, at least in part, by inducing the beiging of WAT.

Neural tone and cardio-renal outcomes in patients with type 2 diabetes mellitus: a review of the literature with a focus on SGLT2 inhibitors

Recent clinical trials involving the systemic effects of sodium-glucose cotransporter 2 inhibitors (SGLT2i) have revealed beneficial outcomes pertaining to the microvascular sequelae of type 2 diabetes mellitus (T2DM) such as nephropathy, as well as macrovascular effects such as major adverse cardiovascular effects (MACE). Such findings have spurred the elevation of these agents to level A-tiers of recommendation within clinical guidelines addressing the management of complicated T2DM. While the mechanisms of SGLTi (-flozin drugs) are still being elucidated, a paucity of data exists within the literature appraising the role of neuromodulation and associated mechanisms in the aforementioned outcome studies. Given the role of the nervous system in orchestrating the pathologic processes that hamper cardio-renal status, insight into this topic offers an expanded perspective on T2DM. In this review we investigate the mechanisms by which SGLTi improve cardio-renal function in T2DM patients with emphases on neural tone and nervous system physiology.

Role of peripheral 5-HT5A receptors in 5-HT-induced cardiac sympatho-inhibition in type 1 diabetic rats

5-HT inhibits cardiac sympathetic neurotransmission in normoglycaemic rats, via 5-HT_1B, 5-HT_1D and 5-HT_5A receptor activation. Since type 1 diabetes impairs the cardiac sympathetic innervation leading to cardiopathies, this study aimed to investigate whether the serotonergic influence on cardiac noradrenergic control is altered in type 1 diabetic rats. Diabetes was induced in male Wistar rats by streptozotocin (50 mg/kg, i.p.). Four weeks later, the rats were anaesthetized, pithed and prepared for producing tachycardic responses by electrical preganglionic stimulation (C₇-T₁) of the cardioaccelerator sympathetic outflow or i.v. noradrenaline bolus injections. Immunohistochemistry was performed to study 5-HT_1B, 5-HT_1D and 5-HT_5A receptor expression in the stellate ganglion from normoglycaemic and diabetic rats. In the diabetic group, i) i.v. continuous infusions of 5-HT induced a cardiac sympatho-inhibition that was mimicked by the 5-HT_1/5A agonist 5-carboxamidotryptamine (without modifying noradrenaline-induced tachycardia), but not by the agonists indorenate (5-HT_1A), CP 93,129 (5-HT_1B), PNU 142633 (5-HT_1D), or LY344864 (5-HT_1F); ii) SB 699551 (5-HT_5A antagonist; i.v.) completely reversed 5-CT-induced cardiac sympatho-inhibition; and iii) 5-HT_5A receptors were more expressed in the stellate ganglion compared to normoglycaemic rats. These results show the prominent role of the peripheral 5-HT_5A receptors prejunctionally inhibiting the cardiac sympathetic drive in type 1 diabetic rats.

Making a case for the combined use of SGLT2 inhibitors and GLP1 receptor agonists for cardiorenal protection

Sodium glucose cotransporter-2 (SGLT2) inhibitors and glucagon-like peptide-1 receptor agonists (GLP-1RA) were initially approved to improve glycemic control in the treatment of type 2 diabetes. Clinical trials have also demonstrated beneficial effects with regards to cardiovascular and renal parameters. Beyond improving glycemic control, these therapies promote weight loss and lower blood pressure when used individually, and in an additive manner when used together. Accordingly, taking advantage of complementary mechanisms of action with the combined use of these two classes of agents to further improve cardiorenal outcomes is conceptually appealing, but has yet to be explored in detail in clinical trials. In this review, we discuss proposed mechanisms for renal protection, clinical benefits, and adverse events associated with the individual and combined use of SGLT2 inhibitors and GLP-1RA. The management of type 2 diabetes has significantly changed over the last few years, moving away from solely glycemic control towards the concurrent management of associated comorbidities in a patient population at significant risk of cardiovascular disease and progression of chronic kidney disease. It is from this perspective that we seek to outline the rationale for the sequential and/or combined use of SGLT2 inhibitors and GLP-1RA in patients with type 2 diabetes.

Sodium glucose cotransporter (SGLT)-2 inhibitors alleviate the renal stress responsible for sympathetic activation

This review focuses on the pathogenic role of sodium glucose cotransporter (SGLT)-2 in the development of renal dysfunction and heart failure in patients with diabetes, by emphasizing the concept of reno-cardiac syndrome (kidney injury worsens cardiac condition) and by substantiating the deleterious effect of sympathetic overdrive in this context. Furthermore, the review proposes a mechanistic hypothesis to explain the benefits of SGLT2 inhibitors, specifically that SGLT-2 inhibitors reduce sympathetic activation at the renal level. To illustrate this point, several examples from both animal experiments and clinical observations are introduced. The bidirectional interaction of the heart and kidney were deeply implicated as an exacerbator of heart failure and renal failure without diabetes. Renal cortical ischemia and abnormal glucose metabolism of tubular epithelial cells are likely to exist as common pathologies in nondiabetic heart failure patients. It is no wonder why SGLT-2 inhibitors are specifically being studied even in the absence of diabetes, both for heart failure and also for renal failure.

Empagliflozin in Heart Failure: Diuretic and Cardiorenal Effects

BACKGROUND

Sodium-glucose cotransporter-2 inhibitors improve heart failure-related outcomes. The mechanisms underlying these benefits are not well understood, but diuretic properties may contribute. Traditional diuretics such as furosemide induce substantial neurohormonal activation, contributing to the limited improvement in intravascular volume often seen with these agents. However, the proximal tubular site of action of the sodium-glucose cotransporter-2 inhibitors may help circumvent these limitations.

METHODS

Twenty patients with type 2 diabetes mellitus and chronic, stable heart failure completed a randomized, placebo-controlled crossover study of empagliflozin 10 mg daily versus placebo. Patients underwent an intensive 6-hour biospecimen collection and cardiorenal phenotyping at baseline and again after 14 days of study drug. After a 2-week washout, patients crossed over to the alternate therapy with the above protocol repeated.

RESULTS

Oral empagliflozin was rapidly absorbed as evidenced by a 27-fold increase in urinary glucose excretion by 3 hours (P<0.0001). Fractional excretion of sodium increased significantly with empagliflozin monotherapy versus placebo (fractional excretion of sodium, 1.2±0.7% versus 0.7±0.4%; P=0.001), and there was a synergistic effect in combination with bumetanide (fractional excretion of sodium, 5.8±2.5% versus 3.9±1.9%; P=0.001). At 14 days, the natriuretic effect of empagliflozin persisted, resulting in a reduction in blood volume (-208 mL [interquartile range, -536 to 153 mL] versus -14 mL [interquartile range, -282 to 335 mL]; P=0.035) and plasma volume (-138 mL, interquartile range, -379 to 154±453 mL; P=0.04). This natriuresis was not, however, associated with evidence of neurohormonal activation because the change in norepinephrine was superior (P=0.02) and all other neurohormones were similar (P<0.34) during the empagliflozin versus placebo period. Furthermore, there was no evidence of potassium wasting (P=0.20) or renal dysfunction (P>0.11 for all biomarkers), whereas both serum magnesium (P<0.001) and uric acid levels (P=0.008) improved.

CONCLUSIONS

Empagliflozin causes significant natriuresis, particularly when combined with loop diuretics, resulting in an improvement in blood volume. However, off-target electrolyte wasting, renal dysfunction, and neurohormonal activation were not observed. This favorable diuretic profile may offer significant advantage in the management of volume status in patients with heart failure and may represent a mechanism contributing to the superior long-term heart failure outcomes observed with these agents. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03027960.

The Influence of Hypertensive Therapies on Circulating Factors: Clinical Implications for SCFAs, FGF21, TNFSF14 and TNF-α

Studying the role of circulatory factors in the pathogenesis of diseases has been key to the development of effective therapies. We sought to examine the effect of antihypertensive therapies on numerous circulatory factors including short chain fatty acids and growth factors in a human cohort. A subset of participants from an earlier study was characterized by their hypertensive and/or treatment status and separated into three groups: (i) normotensives; (ii) untreated hypertensive and (iii) treated hypertensive subjects. Circulating levels of short chain fatty acids, FGF21 and TNF superfamily members were measured as part of this study. Both F2-isoprostane and circulating lipid levels were reanalysed as part of this current study. We found that antihypertensive treatment increased butyrate levels and decreased acetate levels to levels similar to normotensives. We also found that antihypertensive treatments reduced levels of circulating FGF21, TNFSF14 and TNF-α. In conclusion, we identified several circulatory factors that are altered in hypertension.

Sodium-glucose cotransporter-2 inhibitors: Understanding the mechanisms for therapeutic promise and persisting risks

In a healthy person, the kidney filters nearly 200 g of glucose per day, almost all of which is reabsorbed. The primary transporter responsible for renal glucose reabsorption is sodium-glucose cotransporter-2 (SGLT2). Based on the impact of SGLT2 to prevent renal glucose wasting, SGLT2 inhibitors have been developed to treat diabetes and are the newest class of glucose-lowering agents approved in the United States. By inhibiting glucose reabsorption in the proximal tubule, these agents promote glycosuria, thereby reducing blood glucose concentrations and often resulting in modest weight loss. Recent work in humans and rodents has demonstrated that the clinical utility of these agents may not be limited to diabetes management: SGLT2 inhibitors have also shown therapeutic promise in improving outcomes in heart failure, atrial fibrillation, and, in preclinical studies, certain cancers. Unfortunately, these benefits are not without risk: SGLT2 inhibitors predispose to euglycemic ketoacidosis in those with type 2 diabetes and, largely for this reason, are not approved to treat type 1 diabetes. The mechanism for each of the beneficial and harmful effects of SGLT2 inhibitors-with the exception of their effect to lower plasma glucose concentrations-is an area of active investigation. In this review, we discuss the mechanisms by which these drugs cause euglycemic ketoacidosis and hyperglucagonemia and stimulate hepatic gluconeogenesis as well as their beneficial effects in cardiovascular disease and cancer. In so doing, we aim to highlight the crucial role for selecting patients for SGLT2 inhibitor therapy and highlight several crucial questions that remain unanswered.

Kidney and cardiovascular protection with SGLT2 inhibitors: lessons from cardiovascular outcome trials and CREDENCE

The burden of diabetic kidney disease is rising rapidly worldwide, and new therapies are of vital importance to reduce the risk of kidney failure and major cardiovascular events. Of the newer glucose-lowering agents, sodium-glucose co-transporter 2 (SGLT2) inhibitors have shown exciting potential in preventing these adverse events. The results of several large cardiovascular outcome trials, a single dedicated kidney outcome trial and a dedicated heart failure trial, demonstrate substantial clinical benefits for several different SGLT2 inhibitors. Emerging evidence raises the possibility that these benefits may extend to those with non-diabetic chronic kidney disease. This review summarises the current evidence for SGLT2 inhibitor benefits and harms, and examines which patients are most likely to gain from these therapies.

Does empagliflozin modulate the autonomic nervous system among individuals with type 2 diabetes and coronary artery disease? The EMPA-HEART CardioLink-6 Holter analysis

Context

We examined if empagliflozin was associated with modulation of cardiac autonomic tone among subjects with type 2 diabetes and stable coronary artery disease (CAD) relative to placebo.

Methods

Using ambulatory 24-h Holter electrocardiographic data prospectively collected from a randomized trial, we compared changes in heart rate variability (HRV) parameters between empagliflozin- and placebo-assigned subjects over a follow-up period of 6 months. Measured HRV domains included: standard deviation (SD) of NN intervals (SDNN), SD of average NN intervals per 5-min (SDANN), root mean square of successive RR interval differences (RMSSD), % successive NN intervals differing >50 ms (ms) (pNN50), low frequency (LF), high frequency (HF) and the LF/HF ratio (LF:HF). Differences in HRV parameters between the 2 groups were compared with analysis of covariance (ANCOVA). Statistical measures of significance were reported as adjusted differences between the 2 groups and their corresponding 95% confidence intervals.

Results

Sixty-six subjects completed 24-h Holter monitoring at baseline and 6-months. Over 6 months, the change in HRV was similar between subjects treated with empagliflozin vs. placebo for the following parameters: RMSSD -1.2 ms (-6.0 to 3.6 ms); pNN50 0.5% (-2.6 to 3.6%); VLF -907.8 ms² (-2388.8 to 573.1 ms²); LF -341 ms² (-878.7 to 196.7 ms²); HF -33.8 ms² (-111.1 to 43.5 ms²); LF:HF -0.1 (-0.4 to 0.2). Subjects who received placebo experienced an increase in SDNN 18.6 ms (2.8–34.3 ms) and SDANN 20.2 ms (3.2–37.3 ms) relative to those treated with empagliflozin.

Conclusion

Compared to placebo, empagliflozin did not result in changes in autonomic tone among individuals with type 2 diabetes and stable coronary artery disease.

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Sodium-glucose cotransporter-2 (SGLT2) inhibitors’ mechanism of cardiovascular benefit is unknown.

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Impaired autonomic tone is associated with adverse cardiac events.

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Cardiac autonomic tone was assessed with Holter studies from a randomized trial.

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Similar autonomic tone noted between subjects treated with empagliflozin and placebo.

Sodium glucose co-transporter 2 inhibition reduces succinate levels in diabetic mice

BACKGROUND

Type 1 diabetes (T1D) is associated with major chronic microvascular complications which contribute significantly to diabetes associated morbidity. The protein primarily responsible for glucose reabsorption in the kidney is sodium glucose co-transporter 2 (SGLT2). Presently, SGLT2 inhibitors are widely used in diabetic patients to improve blood glucose levels and prevent cardiovascular and renal complications. Given the broad therapeutic application of SGLT2 inhibitors, we hypothesised that SGLT2 inhibition may exert its protective effects via alterations of the gut microbiome and tested this in a type 1 diabetic mouse model of diabetic retinopathy.

AIM

To determine whether the treatment with two independent SGLT2 inhibitors affects gut health in a type 1 diabetic mouse model.

METHODS

The SGLT2 inhibitors empagliflozin or dapagliflozin (25 mg/kg/d) or vehicle dimethylsulfoxide (DMSO) were administered to C57BL/6J, Akita, Kimba and Akimba mice at 10 wk of age for 8 wk via their drinking water. Serum samples were collected and the concentration of succinate and the short chain fatty acid (SCFA) butyric acid was measured using gas chromatography-mass spectrometry. Enzyme-linked immunosorbent assay (ELISA) was performed to determine the concentration of insulin and leptin. Furthermore, the norepinephrine content in kidney tissue was determined using ELISA. Pancreatic tissue was collected and stained with haematoxylin and eosin and analysed using brightfield microscopy.

RESULTS

Due to the presence of the Akita allele, both Akita and Akimba mice showed a reduction in insulin production compared to C57BL/6J and Kimba mice. Furthermore, Akita mice also showed the presence of apoptotic bodies within the pancreatic islets. The acinar cells of Akita and Akimba mice showed swelling which is indicative of acute injury or pancreatitis. After 8 wk of SGLT2 inhibition with dapagliflozin, the intermediate metabolite of gut metabolism known as succinate was significantly reduced in Akimba mice when compared to DMSO treated mice. In addition, empagliflozin resulted in suppression of succinate levels in Akimba mice. The beneficial SCFA known as butyric acid was significantly increased in Akita mice after treatment with dapagliflozin when compared to vehicle treated mice. The norepinephrine content in the kidney was significantly reduced with both dapagliflozin and empagliflozin therapy in Akita mice and was significantly reduced in Akimba mice treated with empagliflozin. In non-diabetic C57BL/6J and Kimba mice, serum leptin levels were significantly reduced after dapagliflozin therapy.

CONCLUSION

The inhibition of SGLT2 reduces the intermediate metabolite succinate, increases SCFA butyric acid levels and reduces norepinephrine content in mouse models of T1D. Collectively, these improvements may represent an important mechanism underlying the potential benefits of SGLT2 inhibition in T1D and its complications.

Risk of orthostatic hypotension associated with sodium-glucose cotransporter-2 inhibitor treatment: A meta-analysis of randomized controlled trials

OBJECTIVE

The aim of this study was to assess the association between sodium-glucose cotransporter-2 (SGLT2) inhibitors and the risk of orthostatic hypotension (OH) in patients with type 2 diabetes mellitus (T2DM).

METHOD

A systematic literature retrieval was performed using PubMed, Embase, and the Cochrane Central Register of Controlled Trials (CENTRAL) from inception up to 16 October 2019. Data for study characteristics and outcomes of interest were extracted from each eligible study. Pooled risk ratios (RRs) with 95% confidence intervals (CI) for OH were calculated using a random-effects model.

RESULT

A total of 16 studies (n = 12,749) were included in our meta-analysis, with a result of 44 incident OH cases (29 in the SGLT2 inhibitor group, and 15 in the control group). The pooled RR was 1.17 (95% CI: 0.65-2.09). There was no evidence that receiving SGLT2 inhibitors increased the risk of OH, when stratified by age, duration of T2DM, or placebo-control or active-control and baseline blood pressure.

CONCLUSION

This meta-analysis suggested that, in general, SGLPT2 inhibitors did not increase the risk of OH in patients with T2DM. The possibility of OH should be, therefore, considered on an individual basis, especially in patients with a history of OH, long duration of T2DM, or comorbidities.

An evaluation of empagliflozin and it's applicability to hypertension as a therapeutic option

INTRODUCTION

Sodium-glucose cotransporter 2 (SGLT2) inhibitors such as Empagliflozin are novel antihyperglycemic drugs approved for the treatment of type 2 diabetes (T2D). In addition to its glucose-lowering effects, Empagliflozin promotes weight loss, blood pressure reduction, and other beneficial metabolic benefits.

AREAS COVERED

This review outlines the pharmacokinetics, pharmacodynamics, safety, and tolerability of Empagliflozin and discusses its role in diabetes-associated hypertension.

EXPERT OPINION

Empagliflozin was the first in class to not only demonstrate safety of SGLT2 inhibition but also cardio- and reno-protective effects in an adequately powered cardiovascular outcome trial. The EMPA-REG study showed significant reductions in mortality from cardiovascular causes, hospitalization for heart failure, and progression of diabetic kidney disease. These benefits cannot be attributed to glycemic control alone, suggesting the involvement of other SGLT2 inhibition-mediated mechanisms. Recent data suggests the potential utility of SGLT2 inhibition in other conditions including type 1 diabetes (T1D) and non-diabetic heart failure patients with clinical trials currently being conducted. In concert with ongoing pre-clinical investigations to unravel the mechanisms contributing to cardiorenal protection, the full therapeutic potential of SGLT2 inhibition will become apparent over the next few years and promises to be one of the major success stories in clinical medicine.

ABBREVIATIONS

T1D: type 1 diabetes; T2D: type 2 diabetes; SGLT2: sodium-glucose cotransporter 2; CVD: cardiovascular disease; SBP: systolic blood pressure; DBP: diastolic blood pressure; SNS: sympathetic nervous system; BP: blood pressure; CV: cardiovascular; ZDF: Zucker diabetic fatty; CKD: chronic kidney disease; FDA: Food and Drug Administration.

Control of 24-hour blood pressure with SGLT2 inhibitors to prevent cardiovascular disease

The presence of hypertension (HTN) in patients with diabetes mellitus (DM) further worsens cardiovascular disease (CVD) prognosis. In addition, masked HTN and abnormal circadian blood pressure (BP) variability are common among patients with DM. Clinical trial data show that sodium-glucose cotransporter 2 inhibitors (SGLT2i) improve CVD prognosis and prevent progression of renal dysfunction in high-risk patients with type 2 DM (T2DM). Consistent reductions in 24-hour, daytime and nocturnal BP have been documented during treatment with SGLT2i in patients with DM and HTN, and these reductions are of a magnitude that is likely to be clinically significant. SGLT2i agents also appear to have beneficial effects on morning, evening and nocturnal home BP. Greater reductions in BP during treatment with SGLT2i have been reported in patient subgroups with higher body mass index, and in those with higher baseline BP. Other documented beneficial effects of SGLT2i include reductions in arterial stiffness and the potential to decrease the apnea-hypopnea index in patients with DM and obstructive sleep apnea. Recent guidelines highlight the important role of SGLT2i as part of the pharmacological management of patients with DM and HTN, and recommend consideration of SGLT2i early in the clinical course to reduce all-cause and CVD mortality in patients with T2DM and CVD. Overall, available data support a role for SGLT2i as effective BP-lowering agents in patients with T2DM and poorly controlled HTN, irrespective of baseline glucose control status. Sustained improvements in 24-hour BP and the 24-hour BP profile are likely to contribute to the CVD benefits of SGLT2i treatment.