The Forgotten Antiproteinuric Properties of Diuretics

Tailored management strategies for IgA nephropathy based on clinical presentations

The treatment landscape for immunoglobulin A nephropathy is rapidly evolving with the introduction of novel therapies targeting diverse disease pathways. Some have already been approved in different countries, while others are under investigation in randomized controlled trials (RCTs) with encouraging results. However, almost all performed RCTs have included only patients with refractory non-nephrotic proteinuria and preserved renal function. Other clinical presentations (rapidly progressive forms, malignant hypertension, thrombotic microangiopathy, nephrotic syndrome) have received less attention and are systematically excluded from RCTs. In contrast, certain aspects, such as the impact of haematuria or management in special populations (e.g. pregnant patients or transplant recipients), remain underexplored. This review proposes therapeutic algorithms to guide treatment decisions in different clinical scenarios while highlighting gaps in current research.

Temporal prevalence and prognostic impact of diabetes mellitus and albuminuria in heart failure with preserved ejection fraction

BACKGROUND

Most patients with heart failure with preserved ejection fraction (HFpEF) have a metabolic phenotype in which comorbidities including diabetes mellitus play an important role. Factors related to impaired glucose metabolism, such as kidney disease, may contribute to adverse clinical events. Albuminuria is an early marker of kidney disease. We assessed the prevalence of impaired glucose metabolism and albuminuria in HFpEF over time, and evaluated its prognostic implications.

METHODS

Consecutive patients referred to our outpatient clinic and diagnosed with HFpEF between March 2015-November 2023 were included in this study. Patients with type 1 diabetes were excluded. Patients were stratified according to baseline glucose metabolism status (DM + for prediabetes and diabetes, or DM-) and albuminuria status (ALB+ or ALB- for albuminuria > 3.0 mg/mmol and normoalbuminuria, respectively). The primary outcome was a composite of HF hospitalizations (HFH) and all-cause mortality, and was analysed using multivariable-adjusted Cox-regression models.

RESULTS

Among 332 patients with HFpEF (median age 77 years; 67% female), 121 (36.4%) were classified as DM-/ALB-, 106 (31.9%) as DM+ /ALB-, 44 (13.3%) as DM-/ALB+, and 61 (18.4%) as DM+ /ALB+. Both baseline DM and ALB were independently associated with the primary outcome after approximately 3 years: adjusted hazard ratio (aHR) 1.93; 95% confidence interval (CI) 1.25-2.97 and 1.58; 95%CI 1.04-2.41, respectively. Patients in the DM+ /ALB+ group showed the highest risk (aHR 2.85; 95%CI 1.57-5.15). After one year, DM/ALB status was re-evaluated in 250 (75%) patients. New DM+ and ALB+ incidence was 3.9% and 22%in those at risk, respectively. Patients particularly changed ALB groups compared to baseline (n = 63, 25.2%); 27 (10.8%) patients recovered from albuminuria. At 3 years follow-up, the primary outcome mainly occurred in patients who consistently showed albuminuria (27.1%) or who recovered from albuminuria (22.2%), and less so in patients who developed albuminuria after one year (13.9%) or who remained free of albuminuria (8.6%) (p = 0.008).

CONCLUSIONS

DM and albuminuria are prevalent in HFpEF at baseline, and re-evaluation one year later still reveals new diagnoses. Both factors are independently associated with adverse outcomes. Albuminuria at any time point remains predictive of adverse outcomes in HFpEF.

RESEARCH INSIGHTS

WHAT IS CURRENTLY KNOWN ABOUT THIS TOPIC?: Diabetes mellitus is an important cardiovascular risk factor in patients with HFpEF, contributing to disease progression and worse outcomes. Albuminuria is a prognostic marker in heart failure patients and more prevalent in patients with diabetes WHAT IS THE KEY RESEARCH QUESTION?: What is prevalence of impaired glucose metabolism and albuminuria in HFpEF over time and how does this translate to prognosis? WHAT IS NEW?: Both DM and albuminuria each independently associated with worse prognosis in HFpEF. Screening 1 year after HFpEF diagnosis yielded incidence rates of 3.9% and 10.8% for DM and prediabetes, respectively, and 22% for albuminuria. Albuminuria at any time point appeared prognostic in HFpEF, also when albuminuria recovered HOW MIGHT THIS STUDY INFLUENCE CLINICAL PRACTICE?: Intermittent screening of HFpEF patients for abnormal glucose metabolism and albuminuria is warranted to optimize risk management.

Blood Pressure Management Strategies and Podocyte Health

Hypertension (HTN) is one of the key global cardiovascular risk factors, which is tightly linked to kidney health and disease development. Podocytes, glomerular epithelial cells that play a pivotal role in maintenance of the renal filtration barrier, are significantly affected by increased glomerular capillary pressure in HTN. Damage or loss of these cells causes proteinuria, which marks the initiation of the HTN-driven renal damage. It goes without saying that effective blood pressure (BP) management should not only mitigate cardiovascular risks but also preserve renal function by protecting podocyte integrity. This review offers a comprehensive examination of current BP management strategies and their implications for podocyte structure and function and emphasizes strategies for the reduction of proteinuria in HTN. We explore primary and secondary antihypertensive agents, including angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, calcium channel blockers, and diuretics, as well as newer therapies (sodium-glucose cotransporter-2 blocking and endothelin receptor antagonism), emphasizing their mechanistic roles in safeguarding podocytes and curtailing proteinuria.

Proteinuria Assessment and Therapeutic Implementation in Chronic Kidney Disease Patients-A Clinical Audit on KDIGO ("Kidney Disease: Improving Global Outcomes") Guidelines

Background/Objectives: Chronic kidney disease (CKD) is a major health problem with a rising prevalence due to comorbidities like diabetes and hypertension. The aim of this research was to audit the assessment and therapeutic management of proteinuria in CKD patients at the Cantonal Hospital Baselland (KSBL) in Switzerland and determine associations between patient comorbidities, rehospitalisation, death, and the quality of therapeutic management. Methods: We analysed data from 427 adults with CKD (eGFR < 45 mL/min/1.73 m2) hospitalised on the internal medicine ward in 2022. Results: The mean age was 85 years (range: 79-89), 45.9% were female, and the median eGFR was 32.8 mL/min/1.73 m2 (range: 25-40). Proteinuria assessment was performed in 120 (28.1%) patients (the ProtU group), and a corresponding treatment was prescribed in 59%. The ProtU group had a higher quota of patients with diabetes (44.1% vs. 33%, p = 0.048) and obesity (21.2% vs. 12.5%, p = 0.039) when compared to the group without proteinuria assessment (the Ustix group). Twelve-month survival was not significantly different between the groups (HR: 0.75; 95% CI: 0.488-1.154; p-value = 0.191). However, survival was significantly better in patients who received an antiproteinuric treatment compared to those who did not (HR: 0.30; 95% CI: 0.121-0.0761; p = 0.011). Conclusions: Improvements need to be made in managing CKD at the KSBL in accordance with the guidelines.

Albuminuria: An Underappreciated Risk Factor for Cardiovascular Disease

Albuminuria, an established biomarker of the progression of chronic kidney disease, is also recognized as a biomarker for the risk of cardiovascular disease. Elevated urinary albumin excretion indicates kidney damage and systemic vascular disease, including myocardial capillary disease and arterial stiffness. Albuminuria is associated with an increased risk of coronary artery disease, stroke, heart failure, arrhythmias, and microvascular disease. There are now several therapeutic agents that can lead to albuminuria lowering and a reduction in cardiovascular risk. However, screening for albuminuria is still low. Considering the importance of multidisciplinary management of patients with cardiovascular disease, it is crucial that health care professionals managing such patients are aware of the benefits of albuminuria surveillance and management.

Inhibition of intrarenal PRR-RAS pathway by Ganoderma lucidum polysaccharide peptides in proteinuric nephropathy

Excessive proteinuria leads to renal dysfunction and damage. Ganoderma lucidum polysaccharide peptide (GL-PP) and Ganoderma lucidum polysaccharide peptide 2 (GL-PP2) are biologically active compounds extracted from Ganoderma lucidum. GL-PP has a relative molecular weight of 37,121 with 76.39 % polysaccharides and 16.35 % polypeptides, while GL-PP2 has a relative molecular weight of 31,130, composed of 64.14 % polysaccharides and 17.73 % polypeptides. The xylose: mannose: glucose monosaccharide ratios in GL-PP and GL-PP2 were 4.83:1:7.03 and 2.35:1:9.38, respectively. In this study, we investigated the protective effects of GL-PP and GL-PP2 on proteinuria-induced renal dysfunction and damage using rat and cell models. Both compounds reduced kidney injury, proteinuria, and inhibited the (pro)renin receptor (PRR)-renin-angiotensin system (RAS) pathway, inflammatory cell infiltration, oxidative stress, and fibrosis. GL-PP2 showed stronger inhibition of cyclooxygenase-2 and inducible nitric oxide synthase proteins compared to GL-PP. In cell models, both compounds displayed anti-inflammatory properties and improved cellular viability by inhibiting the PRR-RAS pathway. GL-PP2 has higher feasibility and productivity than GL-PP in pharmacology and industrial production. It shows promise in treating proteinuria-induced renal disease with superior anti-inflammatory effects and economic, safe industrial application prospects. Further research is needed to compare efficacy, mechanisms, clinical applications, and commercial feasibility of GL-PP and GL-PP2.

Nephrotic syndrome: pathophysiology and consequences

In patients with kidney disease, nephrotic syndrome can lead to several complications including progressive kidney dysfunction. Proteinuria may lead to the formation of cellular or fibrous crescents with reciprocal development of rapidly progressive glomerulonephritis or focal glomerulosclerosis. Proteinuria may also cause overload and dysfunction of tubular epithelial cells, eventually resulting in tubular atrophy and interstitial fibrosis. Hypoalbuminemia is usually associated with increased risk of mortality and kidney dysfunction. Dyslipidemia may increase the risk of atherosclerotic complications, cause podocyte dysfunction and contribute to vascular thrombosis. Urinary loss of anticoagulants and overproduction of coagulation factors may facilitate a hypercoagulable state. Edema, hypogammaglobulinemia, loss of complement factors, and immunosuppressive therapy can favor infection. Treatment of these complications may reduce their impact on the severity of NS. Nephrotic syndrome is a kidney disorder that can worsen the quality of life and increase the risk of kidney disease progression.

Sodium-glucose cotransporter-2 inhibitor use in kidney transplant recipients

Sodium-glucose cotransporter-2 inhibitors (SGLT2i) are novel oral hypoglycemic agents garnering much attention for their substantial benefits. These recent data have positioned SGLT2i at the forefront of diabetic chronic kidney disease (CKD) and heart failure management. SGLT2i use post-kidney transplant is an emerging area of research. Highlights from this mini review include the following: Empagliflozin is the most prescribed SGLT2i in kidney transplant recipients (KTRs), median time from transplant to initiation was 3 years (range: 0.88-9.6 years). Median baseline estimated glomerular filtration rate (eGFR) was 66.7 mL/min/1.73 m2 (range: 50.4-75.8). Median glycohemoglobin (HgbA1c) at initiation was 7.7% (range: 6.9-9.3). SGLT2i were demonstrated to be effective short-term impacting HgbA1c, eGFR, hemoglobin/hematocrit, serum uric acid, and serum magnesium levels. They are shown to be safe in KTRs with low rates of infections, hypoglycemia, euglycemic diabetic ketoacidosis, and stable tacrolimus levels. More data is needed to demonstrate long-term outcomes. SGLT2i appear to be safe, effective medications for select KTRs. Our present literature, though limited, is founded on precedent robust research in CKD patients with diabetes. Concurrent research/utilization of SGLT2i is vital to not only identify long-term patient, graft and cardiovascular outcomes of these agents, but also to augment management in KTRs.

Therapeutic roles of thiazides and loop diuretics in blood pressure control and renal protection against chronic kidney disease

Fluid overload secondary to loss of functional nephron mass can elevate blood pressure, which is characteristic of hypertension shown in chronic kidney disease (CKD). Therefore, it is logical to use diuretics at appropriate dose to lower blood pressure in patients with CKD and hypertension. Despite the theoretical background on the use of diuretics in CKD, there have been no definitive data on the effectiveness or safety of diuretics as first-line therapy for the management of hypertension in patients with CKD. Results from some clinical trials have demonstrated that diuretics would not lower blood pressure. They could even worsen electrolyte imbalance and kidney function when they are administered in patients with CKD. Major clinical practice guidelines on management of blood pressure or CKD have stated that evidence for benefits of thiazide diuretics is not conclusive yet in patients with advanced CKD, although loop diuretics are often effective for volume control at lower glomerular filtration rate. Recently, evidence for diuretics as effective blood pressure lowering agents in patients with advanced CKD is increasing. Renoprotective effect of thiazide or loop diuretics might represent a consequence of their influence on blood pressure or their ability to potentiate the effect of renin-angiotensin system blockade by making intraglomerular pressure more renin-angiotensin system-dependent, although their direct benefit on renal function remains controversial. This review summarizes recent data on the possible role of diuretics in lowering blood pressure, slowing the progression of kidney disease, and reducing cardiovascular risk in CKD patients.

Change in albuminuria as a surrogate endpoint for cardiovascular and renal outcomes in patients with diabetes

For the purpose of predicting clinical outcomes in patients with diabetes and chronic kidney disease, change in albuminuria is a good candidate to be a surrogate marker for future cardiovascular events and progression of kidney disease. Spot urine albumin/creatinine ratio is convenient and recognized as a viable alternative to 24-h albumin, with some limitations. Although there is sufficient evidence to validate its use in clinical trials as a surrogate endpoint for renal outcomes, this is not yet the case for cardiovascular outcomes. While change in albuminuria as a primary or secondary endpoint is trial-specific, its use should be encouraged, nonetheless.

Lupus nephropathy beyond immunosuppression: Searching for nephro and cardioprotection

Renal involvement in systemic lupus erythematosus (SLE) represents one of the most frequent organ manifestations, often leading to end-stage kidney disease (ESKD). Several therapies have been tested in patients with lupus nephritis (LN) to prevent further organ damage. The effectiveness of immunosuppressive therapy as a treatment for LN is abundant, supported by multiple clinical trials that have shown its efficacy in preventing the development of chronic kidney disease (CKD). In addition to immunosuppressive therapy, several traditional and recent therapies aimed at nephroprotection in patients with proteinuric chronic kidney disease are gaining importance in the setting of LN. Thus, immunosuppressive therapy should be accompanied by nephro- and cardioprotective measures to control cardiovascular risk factors and proteinuria to ensure a better renal prognosis. Despite this, the literature on these specific measures is relatively scarce, with recommendations focused on the blockade of the renin-angiotensin-aldosterone system (RAAS). This review explores the pharmacological options available for cardiovascular and renal protection outside the usual treatment schemes.

Use of Thiazides to Treat Hypertension and Advanced CKD

PURPOSE OF REVIEW

Hypertension is often difficult to control in patients with CKD as manifested by suboptimal control rates in this population. Use of thiazides in CKD patients has been limited as these agents are thought to be ineffective in reducing blood pressure in people with advanced CKD. This review summarizes recent studies impacting indications and safety of use of thiazide in patients with CKD and discusses the mechanism of how thiazides reduce blood pressure.

RECENT FINDINGS

Chlorthalidone reduces blood pressure compared to placebo in patients with advanced CKD, challenging the belief that thiazide diuretics lose efficacy at lower levels of GFR. Recent clinical trial data indicate that thiazides are effective in patients with advanced kidney disease for blood pressure lowering. However, monitoring of electrolytes and kidney function is important to ensure patient safety when prescribing these agents in patients with CKD.

Safety and efficacy of the SGLT2 inhibitor dapagliflozin in patients with systemic lupus erythematosus: a phase I/II trial

OBJECTIVE

Sodium-glucose cotransporter-2 inhibitors have been identified profound renal/cardiac protective effects in different diseases. Here, we assessed the safety and efficacy of dapagliflozin among adult patients with systemic lupus erythematosus (SLE).

METHODS

We conducted a single-arm, open-label, investigator-initiated phase I/II trial of dapagliflozin in Chinese patients with SLE with/without lupus nephritis (LN). Patients received oral dapagliflozin at a daily dose of 10 mg added to the standard of care for 6 months. The primary end point was the safety profile. The secondary efficacy end points were composite assessments of disease activity.

RESULTS

A total of 38 eligible patients were enrolled. Overall, 19 (50%) adverse events (AEs) were recorded, including 8 (21%) AEs leading to drug discontinuation, of which 4 (10.5%) were attributed to dapagliflozin. Two serious AEs (one of major lupus flare and one of fungal pneumonia) were recorded. Lower urinary tract infection was observed in one (2.63%) patient. The secondary end points revealed no improvement of SLE Disease Activity Index scores or proteinuria (among 17 patients with LN); the cumulative lupus flare rate was 18%, and a reduction of ~30% in the prednisone dose was captured. Net changes in body mass index (-0.50 kg/m2), systolic blood pressure (-3.94 mm Hg) and haemoglobin levels (+8.26 g/L) were detected. The overall estimated glomerular filtration rate (eGFR) was stable, and there was an improvement in the eGFR slope among patients with LN with a baseline eGFR <90 mL/min/1.73 m2.

CONCLUSION

Dapagliflozin had an acceptable safety profile in adult patients with SLE. Its possible renal/cardiac protective effects and long-term safety issues in patients with SLE, patients with LN in particular, call for further exploration.

TRIAL REGISTRATION NUMBER

ChiCTR1800015030.

Recent Advances in the Emerging Therapeutic Strategies for Diabetic Kidney Diseases

Diabetic kidney disease (DKD) is one of the most common causes of end-stage renal disease worldwide. The treatment of DKD is strongly associated with clinical outcomes in patients with diabetes mellitus. Traditional therapeutic strategies focus on the control of major risk factors, such as blood glucose, blood lipids, and blood pressure. Renin–angiotensin–aldosterone system inhibitors have been the main therapeutic measures in the past, but the emergence of sodium–glucose cotransporter 2 inhibitors, incretin mimetics, and endothelin-1 receptor antagonists has provided more options for the management of DKD. Simultaneously, with advances in research on the pathogenesis of DKD, some new therapies targeting renal inflammation, fibrosis, and oxidative stress have gradually entered clinical application. In addition, some recently discovered therapeutic targets and signaling pathways, mainly in preclinical and early clinical trial stages, are expected to provide benefits for patients with DKD in the future. This review summarizes the traditional treatments and emerging management options for DKD, demonstrating recent advances in the therapeutic strategies for DKD.

New Strategies for Volume Control in Patients with Diabetes Mellitus, a Narrative Review

Sodium is reabsorbed all along the renal tubules. The positive impacts of sodium-glucose cotransporter-2 inhibitors (SGLT2i), angiotensin receptor neprilysin inhibitor (ARNI) and mineralocorticoid receptor antagonists (MRA) on hard renal and/or cardiac endpoints calls for the role of diuretics in nephroprotection and cardioprotection in patients with diabetes mellitus to be reviewed. Here, we review: (a) the mechanisms of action of the available natriuretics; (b) the physiological adaptations to chronic loop diuretic usage that lead to increased sodium reabsorption in the proximal and distal convoluted tubules; (c) the physiology of sodium retention in patients with diabetes mellitus; and (d) the mechanisms of aldosterone breakthrough. We show the rationale for combined diuretics to target not only the loop of Henle, but also the proximal and distal convoluted tubules. Indeed, higher residual proteinuria in patients treated with renin-angiotensin-aldosterone system (RAAS) blockers portends poorer renal and cardiovascular outcomes. Diuretics are known to optimize the reduction of proteinuria, in addition to RAAS blockers, but may favor aldosterone breakthrough in the absence of MRA. The aim of our study is to support a combined diuretics strategy to improve the management of patients with diabetes mellitus and chronic kidney disease or heart failure.

Thiazide and the Thiazide-Like Diuretics: Review of Hydrochlorothiazide, Chlorthalidone, and Indapamide

The term thiazide is universally understood to refer to diuretics that exert their principal action in the distal tubule. The thiazide class is heterogenous and can be further subdivided into compounds containing the benzothiadiazine ring structure-the thiazide-type (e.g., hydrochlorothiazide)-and those lacking the benzothiadiazine ring-the thiazide-like (e.g., chlorthalidone and indapamide) drugs. Thiazide-like agents are longer acting and constitute the diuretics used in most of the cardiovascular outcome trials that established benefits of treatment with diuretics, but pragmatic aspects, such as lack of availability in convenient formulations, limit their use. Regardless of class heterogeneity, thiazides have retained importance in the management of hypertension for over 60 years. They are reliably effective as monotherapy in a majority of hypertensive patients, and augment the efficacy of other classes of antihypertensives when used in combination. Importantly, a thiazide-based treatment regimen lowers cardiovascular events, and their sturdy effect reinforces their place among the recommended first-line agents to treat hypertension in major domestic and international hypertension guidelines. There are few head-to-head comparisons within the class, but potential differences have been explored indirectly as well as in non-blood pressure mechanisms and potential pleiotropic properties. Until proven otherwise, the importance of these differences remains speculative, and clinicians should assume that cardiovascular events will be lowered similarly across agents when equivalent blood pressure reduction occurs. Thiazides remain underutilized, with only about one-third of hypertensive patients receiving them. For many patients, however, a thiazide is an indispensable component of their regimen to achieve adequate blood pressure control.

Integration of a multicomponent intervention for hypertension into primary healthcare services in Singapore-A cluster randomized controlled trial

BACKGROUND

Despite availability of clinical practice guidelines for hypertension management, blood pressure (BP) control remains sub-optimal (<30%) even in high-income countries. This study aims to assess the effectiveness of a potentially scalable multicomponent intervention integrated into primary care system compared to usual care on BP control.

METHODS AND FINDINGS

A cluster-randomized controlled trial was conducted in 8 government clinics in Singapore. The trial enrolled 916 patients aged ≥40 years with uncontrolled hypertension (systolic BP (SBP) ≥140 mmHg or diastolic BP (DBP) ≥90 mmHg). Multicomponent intervention consisted of physician training in risk-based treatment of hypertension, subsidized losartan-HCTZ single-pill combination (SPC) medications, nurse training in motivational conversations (MCs), and telephone follow-ups. Usual care (controls) comprised of routine care in the clinics, no MC or telephone follow-ups, and no subsidy on SPCs. The primary outcome was mean SBP at 24 months' post-baseline. Four clinics (447 patients) were randomized to intervention and 4 (469) to usual care. Patient enrolment commenced in January 2017, and follow-up was during December 2018 to September 2020. Analysis used intention-to-treat principles. The primary outcome was SBP at 24 months. BP at baseline, 12 and 24 months was modeled at the patient level in a likelihood-based, linear mixed model repeated measures analysis with treatment group, follow-up, treatment group × follow-up interaction as fixed effects, and random cluster (clinic) effects. A total of 766 (83.6%) patients completed 2-year follow-up. A total of 63 (14.1%) and 87 (18.6%) patients in intervention and in usual care, respectively, were lost to follow-up. At 24 months, the adjusted mean SBP was significantly lower in the intervention group compared to usual care (-3.3 mmHg; 95% CI: -6.34, -0.32; p = 0.03). The intervention led to higher BP control (odds ratio 1.51; 95% CI: 1.10, 2.09; p = 0.01), lower odds of high (>20%) 10-year cardiovascular risk score (OR 0.67; 95% CI: 0.47, 0.97; p = 0.03), and lower mean log albuminuria (-0.22; 95% CI: -0.41, -0.02; p = 0.03). Mean DBP, mortality rates, and serious adverse events including hospitalizations were not different between groups. The main limitation was no masking in the trial.

CONCLUSIONS

A multicomponent intervention consisting of physicians trained in risk-based treatment, subsidized SPC medications, nurse-delivered motivational conversation, and telephone follow-ups improved BP control and lowered cardiovascular risk. Wide-scale implementation of a multicomponent intervention such as the one in our trial is likely to reduce hypertension-related morbidity and mortality globally.

TRIAL REGISTRATION

Trial Registration: Clinicaltrials.gov NCT02972619.

A Shared Nephroprotective Mechanism for Renin-Angiotensin-System Inhibitors, Sodium-Glucose Co-Transporter 2 Inhibitors, and Vasopressin Receptor Antagonists: Immunology Meets Hemodynamics

A major paradigm in nephrology states that the loss of filtration function over a long time is driven by a persistent hyperfiltration state of surviving nephrons. This hyperfiltration may derive from circulating immunological factors. However, some clue about the hemodynamic effects of these factors derives from the effects of so-called nephroprotective drugs. Thirty years after the introduction of Renin-Angiotensin-system inhibitors (RASi) into clinical practice, two new families of nephroprotective drugs have been identified: the sodium-glucose cotransporter 2 inhibitors (SGLT2i) and the vasopressin receptor antagonists (VRA). Even though the molecular targets of the three-drug classes are very different, they share the reduction in the glomerular filtration rate (GFR) at the beginning of the therapy, which is usually considered an adverse effect. Therefore, we hypothesize that acute GFR decline is a prerequisite to obtaining nephroprotection with all these drugs. In this study, we reanalyze evidence that RASi, SGLT2i, and VRA reduce the eGFR at the onset of therapy. Afterward, we evaluate whether the extent of eGFR reduction correlates with their long-term efficacy. The results suggest that the extent of initial eGFR decline predicts the nephroprotective efficacy in the long run. Therefore, we propose that RASi, SGLT2i, and VRA delay kidney disease progression by controlling maladaptive glomerular hyperfiltration resulting from circulating immunological factors. Further studies are needed to verify their combined effects.

Understanding the protective effects of SGLT2 inhibitors in type 2 diabetes patients with chronic kidney disease

INTRODUCTION

Sodium-glucose co-transporter type 2 inhibitors (SGLT2is) were developed as glucose-lowering agents for the management of type 2 diabetes (T2D). Unexpectedly, they showed a significant reduction in hospitalization for heart failure and hard renal outcomes in patients with and without T2D. Underlying mechanisms remain a matter of debate.

AREAS COVERED

We summarize the protective renal effects of SGLT2is in patients with cardiovascular disease, chronic kidney disease (CKD, especially with albuminuria) or heart failure; a description of the safety of SGLT2is, with a special focus on the risk/benefit balance in people with stage 3 CKD; a comprehensive discussion of mechanisms that could explain nephro-protection; a reappraisal of the positioning of SGLT2is in recent international guidelines.

EXPERT OPINION

Several mechanisms could contribute to improved renal prognosis with SGLT2is, among which a reduction in intraglomerular pressure by restoring the tubuloglomerular feedback, a diuretic effect that contributes to lower albuminuria and renal decongestion, especially if fluid overload is present, a reduction in renal oxygen consumption, an improvement of heart failure status with less cardiorenal syndrome and a lower risk of acute renal injury. All these effects may be mutually not exclusive, and their respective contribution may differ according to patient characteristics.

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.