SGLT2 inhibitor lowers serum uric acid through alteration of uric acid transport activity in renal tubule by increased glycosuria

Effects and Mechanisms of Dapagliflozin Treatment on Ambulatory Blood Pressure in Diabetic Patients with Hypertension

Background

Studies have shown that dapagliflozin has antihypertensive effects. However, the effects and mechanisms of dapagliflozin on ambulatory blood pressure (ABP) have not been fully evaluated. In this study, we aimed to evaluate the effects of dapagliflozin treatment on ABP in patients with type 2 diabetes and hypertension.

Material/Methods

Patients were prospectively enrolled and divided into 2 groups: dapagliflozin treatment group (n=182) and no dapagliflozin treatment group (n=304). Clinical characteristics and measures of treatment, serum uric acid (SUA), 24-h urinary UA (UUA) excretion, and 24-h ABP were collected. The effects and mechanisms of dapagliflozin on 24-h ABP were evaluated.

Results

After 3 months, the patients without dapagliflozin treatment had higher SUA, lower 24-h UUA excretion, and higher 24-h and daytime systolic blood pressure (SBP) (P<0.05) compared to patients with dapagliflozin treatment. After adjusting for covariates, results showed that dapagliflozin treatment was significantly associated with reduced 24-h SBP (β=−0.29 and P=0.02) and reduced daytime SBP (β=−0.33 and P=0.009). After additionally adjusting for SUA and 24-h UUA excretion, there were no significant relationships found between dapagliflozin treatment and 24-h (β=−012, P=0.10) and daytime SBP (β=−0.20, P=0.06).

Conclusions

In patients with diabetes and hypertension, dapagliflozin treatment was associated with reduced 24-h and daytime SBP, which could be related to the drug’s effect of increasing 24-h UUA excretion.

Sodium-Glucose Cotransporter-2 Inhibitor Immediately Decreases Serum Uric Acid Levels in Type 2 Diabetic Patients

BACKGROUND Sodium-glucose cotransporter-2 (SGLT2) inhibitors are new antihyperglycemic drugs for type 2 diabetes. SGLT2 inhibitors ameliorate cardiovascular morbidity and mortality as well as kidney disease progression by reducing body weight (BW), blood pressure (BP), visceral adiposity, albuminuria, and serum uric acid and blood glucose levels. However, it is not clear which effects are pronounced, and what mechanisms are associated with these effects. MATERIAL AND METHODS This study recruited patients with type 2 diabetes who were prescribed an SGLT2 inhibitor for the first time in our outpatient department. Clinical parameters were measured before and 6 months after the administration of the SGLT2 inhibitor, without the addition of new drugs and dose changes for all prescribed drugs. RESULTS This study recruited 24 patients with type 2 diabetes. No significant differences in BP, glycated hemoglobin (HbA1c) levels, and low-density lipoprotein cholesterol levels were observed after SGLT2 inhibitor administration. In contrast, BW and serum uric acid levels decreased significantly, and the fractional excretion of uric acid (FEUA) increased significantly after administration. While no significant relationships were observed between serum uric acid and FEUA with respect to the percentage changes from baseline values, the percentage changes in serum uric acid levels from baseline were significantly and positively associated with those in serum creatinine levels. CONCLUSIONS Serum uric acid levels were immediately decreased owing to the administration of SGLT2 inhibitor, but BP, blood glucose, and serum lipid levels were unchanged. These changes in serum uric acid levels may be associated with changes in renal function.

Glucose, Fructose, and Urate Transporters in the Choroid Plexus Epithelium

The choroid plexus plays a central role in the regulation of the microenvironment of the central nervous system by secreting the majority of the cerebrospinal fluid and controlling its composition, despite that it only represents approximately 1% of the total brain weight. In addition to a variety of transporter and channel proteins for solutes and water, the choroid plexus epithelial cells are equipped with glucose, fructose, and urate transporters that are used as energy sources or antioxidative neuroprotective substrates. This review focuses on the recent advances in the understanding of the transporters of the SLC2A and SLC5A families (GLUT1, SGLT2, GLUT5, GLUT8, and GLUT9), as well as on the urate-transporting URAT1 and BCRP/ABCG2, which are expressed in choroid plexus epithelial cells. The glucose, fructose, and urate transporters repertoire in the choroid plexus epithelium share similar features with the renal proximal tubular epithelium, although some of these transporters exhibit inversely polarized submembrane localization. Since choroid plexus epithelial cells have high energy demands for proper functioning, a decline in the expression and function of these transporters can contribute to the process of age-associated brain impairment and pathophysiology of neurodegenerative diseases.

Glucose transporters in the kidney in health and disease

The kidneys filter large amounts of glucose. To prevent the loss of this valuable fuel, the tubular system of the kidney, particularly the proximal tubule, has been programmed to reabsorb all filtered glucose. The machinery involves the sodium-glucose cotransporters SGLT2 and SGLT1 on the apical membrane and the facilitative glucose transporter GLUT2 on the basolateral membrane. The proximal tubule also generates new glucose, particularly in the post-absorptive phase but also to enhance bicarbonate formation and maintain acid-base balance. The glucose reabsorbed or formed by the proximal tubule is primarily taken up into peritubular capillaries and returned to the systemic circulation or provided as an energy source to further distal tubular segments that take up glucose by basolateral GLUT1. Recent studies provided insights on the coordination of renal glucose reabsorption, formation, and usage. Moreover, a better understanding of renal glucose transport in disease states is emerging. This includes the kidney in diabetes mellitus, when renal glucose retention becomes maladaptive and contributes to hyperglycemia. Furthermore, enhanced glucose reabsorption is coupled to sodium retention through the sodium-glucose cotransporter SGLT2, which induces secondary deleterious effects. As a consequence, SGLT2 inhibitors are new anti-hyperglycemic drugs that can protect the kidneys and heart from failing. Recent studies discovered unique roles for SGLT1 with implications in acute kidney injury and glucose sensing at the macula densa. This review discusses established and emerging concepts of renal glucose transport, and outlines the need for a better understanding of renal glucose handling in health and disease.

Effects of luseogliflozin on arterial properties in patients with type 2 diabetes mellitus: The multicenter, exploratory LUSCAR study

Sodium-glucose cotransporter 2 (SGLT2) inhibitors reduce the occurrence of cardiovascular and renal complications in patients with type 2 diabetes mellitus (T2DM) and represent guideline-recommended therapy in this indication. However, precise mechanisms underlying the beneficial cardiovascular effects of SGLT2 inhibitors are not fully understood. This study investigated the effects of the SGLT2 inhibitor, luseogliflozin, on arterial properties and home blood pressure (BP) in patients with T2DM. This multicenter, single-arm study enrolled adults with T2DM, glycosylated hemoglobin (HbA1c) 6.5%-8.9% in the previous 4 weeks, and an indication for new/additional antidiabetic therapy. Luseogliflozin 2.5 mg/d was given for 12 weeks. Primary outcome was change in cardio-ankle vascular index (CAVI) from baseline to Week 4 and Week 12. Home and office BP, BP variability, and metabolic parameters were secondary endpoints. Forty-seven patients (mean age 63.5 ± 10.7 years) treated with luseogliflozin were included in the full analysis set. CAVI did not change significantly from baseline (mean [95% confidence interval] 8.67 [8.37-8.97]) to Week 12 (8.64 [8.38-8.91]; P = .750), but there were significant reductions from baseline in morning home BP, HbA1c, body weight, body mass index, and serum uric acid levels during luseogliflozin therapy. The reduction in morning home systolic BP was ≥ 5 mm Hg and was independent of baseline BP and BP control status. In conclusion, there was no change in arterial stiffness (based on CAVI) during treatment with luseogliflozin, but changes in BP and metabolic parameters were consistent with the known beneficial effects of SGLT2 inhibitors in T2DM.

SGLT-2 inhibitors and nephroprotection: current evidence and future perspectives

Chronic kidney disease (CKD) is a major public health issue and an independent risk factor for cardiovascular and all-cause mortality. Diabetic kidney disease develops in 30-50% of diabetic patients and it is the leading cause of end-stage renal disease in the Western world. Strict blood pressure control and renin-angiotensin system (RAS) blocker use are the cornerstones of CKD treatment; however, their application in everyday clinical practice is not always ideal and in many patients CKD progression still occurs. Accumulated evidence in the past few years clearly suggests that sodium-glucose co-transporter-2 (SGLT-2) inhibitors present potent nephroprotective properties. In clinical trials in patients with type 2 diabetes mellitus, these agents were shown to reduce albuminuria and proteinuria by 30-50% and the incidence of composite hard renal outcomes by 40-50%. Furthermore, their mechanism of action appears rather solid, as they interfere with the major mechanism of proteinuric CKD progression, i.e., glomerular hypertension and hyperfiltration. The present review summarizes the current evidence from human trials on the effects of SGLT-2 inhibitors on nephroprotection and discusses their position in everyday clinical practice.

Tubular effects of sodium-glucose cotransporter 2 inhibitors: intended and unintended consequences

PURPOSE OF REVIEW

Sodium-glucose cotransporter 2 (SGLT2) inhibitors are antihyperglycemic drugs that act by inhibiting renal sodium-glucose cotransport. Here we present new insights into 'off target', or indirect, effects of SGLT2 inhibitors.

RECENT FINDINGS

SGLT2 inhibition causes an acute increase in urinary glucose excretion. In addition to lowering blood glucose, there are several other effects that contribute to the overall beneficial renal and cardiovascular effects. Reabsorption of about 66% of sodium is accomplished in the proximal tubule and dependent on the sodium-hydrogen exchanger isoform 3 (NHE3). SGLT2 colocalizes with NHE3, and high glucose levels reduce NHE3 activity. The proximal tubule is also responsible for the majority of phosphate (Pi) reabsorption. SGLT2 inhibition is associated with increases in plasma Pi, fibroblast growth factor 23 and parathyroid hormone levels in nondiabetics and type 2 diabetes mellitus. Studies in humans identified a urate-lowering effect by SGLT2 inhibition which is possibly mediated by urate transporter 1 (URAT1) and/or glucose transporter member 9 in the proximal tubule. Of note, magnesium levels were also found to increase under SGLT2 inhibition, an effect that was preserved in nondiabetic patients with hypomagnesemia.

SUMMARY

Cardiorenal effects of SGLT2 inhibition might involve, in addition to direct effects on glucose homeostasis, effects on NHE3, phosphate, urate, and magnesium homeostasis.

Mathematical modeling analysis of hepatic uric acid disposition using human sandwich-cultured hepatocytes

Uric acid is biosynthesized from purine by xanthine oxidase (XO) mainly in the liver and is excreted into urine and feces. Although several transporters responsible for renal and intestinal handling of uric acid have been reported, information on hepatic transporters is limited. In the present study, we studied quantitative contribution of transporters for hepatic handling of uric acid by mathematical modeling analysis in human sandwich-cultured hepatocytes (hSCH). Stable isotope-labeled hypoxanthine, hypoxanthine-¹³C2,¹⁵N (HX), was incubated with hSCH and formed ¹³C2,¹⁵N-labeled xanthine (XA) and uric acid (UA) were measured by LC-MS/MS time dependently. Rate constants for metabolism and efflux and uptake transport across sinusoidal and bile canalicular membranes of HX, XA and UA were estimated in the presence of inhibitors of XO and uric acid transporters. An XO inhibitor allopurinol significantly decreased metabolisms of HX and XA. Efflux into bile canalicular lumen was negligible and sinusoidal efflux was considered main efflux pathway of formed UA. Transporter inhibition study highlighted that GLUT9 strongly and MRP4 intermediately contribute to the sinusoidal efflux of UA with minor contribution of NPT1/4. Modeling analysis developed in the present study should be useful for quantitative prediction of uric acid disposition in liver.

[Advantages of therapy with sodium glucose cotransporter type 2 inhibitors in patients with type 2 diabetes mellitus in combination with hyperuricemia and gout]

Currently, only two drugs for reducing uric acid (UA), allopurinol and febuxostat, are registered in the Russian Federation, but their use does not allow to achieve the target level of UA in all cases. According to the results of numerous randomized trials, hyperuricemia and gout are associated with the corresponding components of the metabolic syndrome, including diabetes mellitus. The influence of factors is due to the need to search for new drugs that have a complex effect on several components of metabolic syndrome at once. Potentially attractive in this regard is a new group of drugs for the treatment of type 2 diabetes mellitus inhibitors of the sodium-glucose cotransporter of type 2, which, in addition to the main hypoglycemic actions, showed positive effects on the cardiovascular system, kidneys, as well as lowering UA.

Mechanisms of Cardiovascular Benefits of Sodium Glucose Co-Transporter 2 (SGLT2) Inhibitors: A State-of-the-Art Review

Recent clinical trials have shown that sodium glucose co-transport 2 (SGLT2) inhibitors have dramatic beneficial cardiovascular outcomes. These include a reduced incidence of cardiovascular death and heart failure hospitalization in people with and without diabetes, and those with and without prevalent heart failure. The actual mechanism(s) responsible for these beneficial effects are not completely clear. Several potential theses have been proposed to explain the cardioprotective effects of SGLT2 inhibition, which include diuresis/natriuresis, blood pressure reduction, erythropoiesis, improved cardiac energy metabolism, inflammation reduction, inhibition of the sympathetic nervous system, prevention of adverse cardiac remodeling, prevention of ischemia/reperfusion injury, inhibition of the Na+/H+-exchanger, inhibition of SGLT1, reduction in hyperuricemia, increasing autophagy and lysosomal degradation, decreasing epicardial fat mass, increasing erythropoietin levels, increasing circulating pro-vascular progenitor cells, decreasing oxidative stress, and improving vascular function. The strengths and weaknesses of these proposed mechanisms are reviewed in an effort to try to synthesize and prioritize the mechanisms as they relate to clinical event reduction.

Autophagy-dependent and -independent modulation of oxidative and organellar stress in the diabetic heart by glucose-lowering drugs

Autophagy is a lysosome-dependent intracellular degradative pathway, which mediates the cellular adaptation to nutrient and oxygen depletion as well as to oxidative and endoplasmic reticulum stress. The molecular mechanisms that stimulate autophagy include the activation of energy deprivation sensors, sirtuin-1 (SIRT1) and adenosine monophosphate-activated protein kinase (AMPK). These enzymes not only promote organellar integrity directly, but they also enhance autophagic flux, which leads to the removal of dysfunctional mitochondria and peroxisomes. Type 2 diabetes is characterized by suppression of SIRT1 and AMPK signaling as well as an impairment of autophagy; these derangements contribute to an increase in oxidative stress and the development of cardiomyopathy. Antihyperglycemic drugs that signal through insulin may further suppress autophagy and worsen heart failure. In contrast, metformin and SGLT2 inhibitors activate SIRT1 and/or AMPK and promote autophagic flux to varying degrees in cardiomyocytes, which may explain their benefits in experimental cardiomyopathy. However, metformin and SGLT2 inhibitors differ meaningfully in the molecular mechanisms that underlie their effects on the heart. Whereas metformin primarily acts as an agonist of AMPK, SGLT2 inhibitors induce a fasting-like state that is accompanied by ketogenesis, a biomarker of enhanced SIRT1 signaling. Preferential SIRT1 activation may also explain the ability of SGLT2 inhibitors to stimulate erythropoiesis and reduce uric acid (a biomarker of oxidative stress)—effects that are not seen with metformin. Changes in both hematocrit and serum urate are the most important predictors of the ability of SGLT2 inhibitors to reduce the risk of cardiovascular death and hospitalization for heart failure in large-scale trials. Metformin and SGLT2 inhibitors may also differ in their ability to mitigate diabetes-related increases in intracellular sodium concentration and its adverse effects on mitochondrial functional integrity. Differences in the actions of SGLT2 inhibitors and metformin may reflect the distinctive molecular pathways that explain differences in the cardioprotective effects of these drugs.

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.

The effects of dapagliflozin on cardio-renal risk factors in patients with type 2 diabetes with or without renin-angiotensin system inhibitor treatment: a post hoc analysis

AIMS

Renin-angiotensin system inhibitors (RASi) are the most effective treatments for diabetic kidney disease but significant residual renal risk remains, possibly because of other mechanisms of kidney disease progression unrelated to RAS that may be present. Sodium-glucose co-transporter-2 inhibitors reduce albuminuria and may complement RASi by offering additional renal protection. This post hoc analysis investigated the effects of dapagliflozin on cardio-renal risk factors in patients with type 2 diabetes (T2D) with increased albuminuria treated with or without RASi at baseline.

MATERIALS AND METHODS

We evaluated the effects of dapagliflozin 10 mg/day over 12-24 weeks across 13 placebo-controlled studies in patients with T2D with a urinary albumin-to-creatinine ratio (UACR) ≥30 mg/g at baseline. Patients were divided into two subgroups based on treatment with or without RASi at baseline.

RESULTS

Compared with patients with RASi at baseline (n = 957), patients without RASi (n = 302) were younger, had a shorter duration of diabetes (7 vs. 12 years), higher estimated glomerular filtration rate (eGFR) and lower UACR, serum uric acid (sUA), body weight and systolic blood pressure. Placebo-adjusted treatment effects of dapagliflozin on UACR, eGFR, glycated haemoglobin and haematocrit over 24 weeks were similar across groups. Mean reductions in body weight and sUA were more distinct in patients without RASi treatment at baseline.

CONCLUSIONS

Treatment with dapagliflozin over 24 weeks provides similar clinically relevant improvements in metabolic and haemodynamic parameters, and similar reductions in UACR, in patients with T2D with elevated albuminuria treated with or without RASi at baseline.

The tubular hypothesis of nephron filtration and diabetic kidney disease

Kidney size and glomerular filtration rate (GFR) often increase with the onset of diabetes, and elevated GFR is a risk factor for the development of diabetic kidney disease. Hyperfiltration mainly occurs in response to signals passed from the tubule to the glomerulus: high levels of glucose in the glomerular filtrate drive increased reabsorption of glucose and sodium by the sodium-glucose cotransporters SGLT2 and SGLT1 in the proximal tubule. Passive reabsorption of chloride and water also increases. The overall capacity for proximal reabsorption is augmented by growth of the proximal tubule, which (alongside sodium-glucose cotransport) further limits urinary glucose loss. Hyperreabsorption of sodium and chloride induces tubuloglomerular feedback from the macula densa to increase GFR. In addition, sodium-glucose cotransport by SGLT1 on macula densa cells triggers the production of nitric oxide, which also contributes to glomerular hyperfiltration. Although hyperfiltration restores sodium and chloride excretion it imposes added physical stress on the filtration barrier and increases the oxygen demand to drive reabsorption. Tubular growth is associated with the development of a senescence-like molecular signature that sets the stage for inflammation and fibrosis. SGLT2 inhibitors attenuate the proximal reabsorption of sodium and glucose, normalize tubuloglomerular feedback signals and mitigate hyperfiltration. This tubule-centred model of diabetic kidney physiology predicts the salutary effect of SGLT2 inhibitors on hard renal outcomes, as shown in large-scale clinical trials.

Assessing the Risk for Gout With Sodium-Glucose Cotransporter-2 Inhibitors in Patients With Type 2 Diabetes: A Population-Based Cohort Study

BACKGROUND

Hyperuricemia is common in patients with type 2 diabetes mellitus and is known to cause gout. Sodium-glucose cotransporter-2 (SGLT2) inhibitors prevent glucose reabsorption and lower serum uric acid levels.

OBJECTIVE

To compare the rate of gout between adults prescribed an SGLT2 inhibitor and those prescribed a glucagon-like peptide-1 (GLP1) receptor agonist.

DESIGN

Population-based new-user cohort study.

SETTING

A U.S. nationwide commercial insurance database from March 2013 to December 2017.

PATIENTS

Persons with type 2 diabetes newly prescribed an SGLT2 inhibitor were 1:1 propensity score matched to patients newly prescribed a GLP1 agonist. Persons were excluded if they had a history of gout or had received gout-specific treatment previously.

MEASUREMENTS

The primary outcome was a new diagnosis of gout. Cox proportional hazards regression was used to estimate hazard ratios (HRs) of the primary outcome and 95% CIs.

RESULTS

The study identified 295 907 adults with type 2 diabetes mellitus who were newly prescribed an SGLT2 inhibitor or a GLP1 agonist. The gout incidence rate was lower among patients prescribed an SGLT2 inhibitor (4.9 events per 1000 person-years) than those prescribed a GLP1 agonist (7.8 events per 1000 person-years), with an HR of 0.64 (95% CI, 0.57 to 0.72) and a rate difference of -2.9 (CI, -3.6 to -2.1) per 1000 person-years.

LIMITATION

Unmeasured confounding, missing data (namely incomplete laboratory data), and low baseline risk for gout.

CONCLUSION

Adults with type 2 diabetes prescribed an SGLT2 inhibitor had a lower rate of gout than those prescribed a GLP1 agonist. Sodium-glucose cotransporter-2 inhibitors may reduce the risk for gout among adults with type 2 diabetes mellitus, although future studies are necessary to confirm this observation.

PRIMARY FUNDING SOURCE

Brigham and Women's Hospital.

Extraglycemic Effects of SGLT2 Inhibitors: A Review of the Evidence

Patients with type 2 diabetes (T2D) are often overweight/obese and affected by arterial hypertension, dyslipidaemia, and have high serum levels of uric acid. Moreover, T2D patient have a higher risk of developing cardiovascular or renal complications, which are leading causes of morbidity and mortality in this population. Sodium-glucose cotransporter-2 inhibitors (SGLT2i) are a new class of glucose-lowering medications that block the reabsorption of glucose in the kidney, thereby increasing urinary glucose excretion, and lowering blood glucose levels. The beneficial effects of SGLT2 inhibition extend beyond glycaemic control, and include improvement in blood pressure, body weight, uric acid concentrations, liver steatosis, oxidative stress, and inflammation. In dedicated cardiovascular outcome trials, SGLT2i treatment was associated with a significant reduction in the rate of cardiovascular events and renal endpoints. In this review, we summarize the evidence for extra-glycemic effects of SGLT2i and the potential mechanisms driving cardiorenal protection exerted by this class of medications.

Empagliflozin Attenuates Hyperuricemia by Upregulation of ABCG2 via AMPK/AKT/CREB Signaling Pathway in Type 2 Diabetic Mice

Hyperuricemia (HUA) is a metabolic disease characterized by elevated serum uric acid (SUA). Empagliflozin, a kind of sodium-glucose cotransporter 2 inhibitors, has recently emerged as a new antidiabetic agent by facilitating glucose excretion in urine. Moreover, there was evidence of SUA reduction following treatment with empagliflozin in addition to glycaemic control, while the molecular mechanisms remain unknown. To investigate the potential mechanisms, the model of type 2 diabetes (T2DM) with HUA was established by combination of peritoneal injection of potassium oxonate and intragastric administration of hypoxanthine in KK-Ay mice. A series of method such as RT-PCR, western blot, immunochemistry, immunofluorescence were conducted to explore the mechanism. Our results showed that empagliflozin significantly ameliorated the levels of SUA and blood glucose in T2DM mice with HUA. Furthermore, in both kidney and ileum, empagliflozin obviously promoted protein expression of uric acid (UA) transporter ABCG2, p-AMPK, p-AKT and p-CREB. The same trend was observed in human tubular epithelial (HK-2) cells. Additionally, through application of an AMPK inhibitor (Compound C), it was further confirmed empagliflozin exerted its anti-hyperuricemic effects in an AMPK dependent manner. Meanwhile, with the help of ChIP assay and luciferase reporter gene assay, we found that CREB further activated ABCG2 via binding to the promoter of ABCG2 to induce transcription. Taken together, our study demonstrated that empagliflozin treatment played an essential role in attenuating HUA by upregulation of ABCG2 via AMPK/AKT/CREB signaling pathway.

EMPAGLIFLOZIN IS MORE EFFECTIVE IN REDUCING MICROALBUMINURIA AND ALT LEVELS COMPARED WITH DAPAGLIFLOZIN: REAL LIFE EXPERIENCE

CONTEXT

Sodium Glucose Co-Transporter-2 inhibitors (SGLT2i) are oral antidiabetic agents that can be used with insulin in the treatment of type 2 diabetes mellitus, known for cardiovascular and renal benefits. Dapagliflozin and empagliflozin are available in Turkey and we aimed to evaluate real-life data of using these two molecules with other oral antidiabetic drugs (OAD) or insulin.

SUBJECTS AND METHODS

119 patients (59 women, 60 men) files who had started SGLT2i between 2017-2019 were examined retrospectively until 6 months after the treatment change. Patients' weight, body mass index (BMI), insulin doses, fasting blood glucose, HbA1c, lipid profile, spot urine albumin/creatinine ratio, e-GFR values, ALT, AST, uric acid levels were evaluated at baseline, 3 months and 6 months.

RESULTS

41.2% of patients were using dapagliflozin and 58.8% were using empagliflozin. After 6 months of follow-up, HbA1c decreased from 8.27% to 7.45% (p<0.001). Daily total insulin dose decreased from 84.75 to 75.58 U/day in 3 months (p<0.004). Weight and BMI decreased significantly at 6 months. ALT, AST decreased significantly in patients using insulin (p 0.001 and 0.007), whereas spot urine microalbumin/creatinine ratio decreased at 3 and 6 months (p 0.005 and 0.020). A significant decrease was also observed in uric acid levels (p: 0.026).

CONCLUSIONS

Dapagliflozin and empagliflozin have beneficial effects on decreasing glycemic parameters, weight, transaminases, uric acid and microalbuminuria in the real life environment. We also observed that SGLT2i and insulin combination is as safe and effective as combination with OAD.

Beneficial Effects of Ipragliflozin on the Renal Function and Serum Uric Acid Levels in Japanese Patients with Type 2 Diabetes: A Randomized, 12-week, Open-label, Active-controlled Trial

Objective To examine the add-on effects, compared to the existing antidiabetes treatment, of the sodium-glucose cotransporter 2 inhibitor ipragliflozin on glycemic control and the risk factors of cardiovascular disease (CVD) and chronic kidney disease (CKD) in patients with inadequately controlled type 2 diabetes. Methods This 12-week, randomized, open-label, active-controlled trial included 30 patients with type 2 diabetes who were randomized 1:1 to ipragliflozin and control groups (n=15 each). The ipragliflozin group received 50 mg of ipragliflozin once daily in addition to conventional therapy. The primary outcome was the change in hemoglobin A1c (HbA1c) from the baseline. Secondary outcomes were changes from the baseline in indices of glycemic control, uric acid (UA), renal function, and arterial stiffness. Results The patients' diminished estimated glomerular filtration rate (eGFR) was alleviated in the ipragliflozin group compared to the control group [difference between groups (Δ) =4.6 (95% confidence interval (CI): 1.5-7.7) mL/min/1.73 m², p=0.006] prior to significant improvements in HbA1c and other parameters, including anthropometric indices and arterial stiffness. Furthermore, ipragliflozin add-on therapy resulted in a greater reduction in serum UA levels than control therapy [Δ=-52.3 (95% CI: -85.5-19.1) μmol/L, p=0.003]. The changes in the eGFR with ipragliflozin treatment were associated with ipragliflozin-mediated changes in the UA, even after adjusting for the age, sex, baseline HbA1c, baseline UA, and baseline eGFR (standardized regression coefficient=-0.535, p=0.010). Conclusion Ipragliflozin add-on therapy was associated with beneficial renal effects in parallel with reducing serum UA levels.

Renal Effects of Sodium-Glucose Co-Transporter Inhibitors

Sodium-glucose co-transporter 2 (SGLT2) inhibitors immediately reduce the glomerular filtration rate (GFR) in patients with type 2 diabetes mellitus. When given chronically, they confer benefit by markedly slowing the rate at which chronic kidney disease progresses and are the first agents to do so since the advent of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs). Salutary effects on the kidney were first demonstrated in cardiovascular outcomes trials and have now emerged from trials enriched in subjects with type 2 diabetes mellitus and chronic kidney disease. A simple model that unifies the immediate and long-term effects of SGLT2 inhibitors on kidney function is based on the assumption that diabetic hyperfiltration puts the kidney at long-term risk and evidence that hyperfiltration is an immediate response to a reduced signal for tubuloglomerular feedback, which occurs to the extent that SGLT2 activity mediates a primary increase in sodium and fluid reabsorption by the proximal tubule. This model will likely continue to serve as a useful description accounting for the beneficial effect of SGLT2 inhibitors on the diabetic kidney, similar to the hemodynamic explanation for the benefit of ACEIs and ARBs. A more complex model will be required to incorporate positive interactions between SGLT2 and sodium-hydrogen exchanger 3 in the proximal tubule and between sodium-glucose co-transporter 1 (SGLT1) and nitric oxide synthase in the macula densa. The implication of these latter nuances for day-to-day clinical medicine remains to be determined.

The effects of canagliflozin on gout in type 2 diabetes: a post-hoc analysis of the CANVAS Program

BACKGROUND

Sodium glucose co-transporter 2 inhibitors have been shown to reduce serum urate concentration. The Canagliflozin Cardiovascular Assessment Study (CANVAS) Program integrated data from two similarly designed, randomised, double-blind, placebo-controlled trials (CANVAS and CANVAS-Renal) assessing the cardiovascular and renal safety of canagliflozin compared with placebo in patients with type 2 diabetes. In this post-hoc analysis, we aimed to investigate the effect of canagliflozin compared with placebo on gout in the CANVAS Program.

METHODS

In the CANVAS Program, individuals with type 2 diabetes and an elevated risk of cardiovascular disease were randomly assigned to receive either canagliflozin (100 or 300 mg) or placebo. In this post-hoc analysis, we assessed the effects of canagliflozin versus placebo on serum urate concentration using mixed linear models and the occurrence of either an adverse event attributed to gout flare or the commencement of a drug for gout using Kaplan-Meier analysis with Cox proportional hazards models to determine a hazard ratio (HR) and 95% CIs. All analyses were done according to the principle of intention to treat, and there was no imputation for missing data.

FINDINGS

10 142 participants were included in analyses. At baseline, mean age was 63 years (SD 8), 3633 (36%) participants were female, mean serum urate concentration was 348·9 μmol/L (95·5), and 471 (5%) of participants had a history of gout. Mean follow-up was 3·6 years (SD 2·0) and mean serum urate concentration was -23·3 μmol/L (95% CI -25·4 to -21·3) lower in participants treated with canagliflozin than in those who received placebo, equating to a 6·7% reduction in serum urate (percentage difference -6·7%, 95% CI -7·3 to -6·1). During follow-up, 80 individuals reported an episode of gout flare and 147 commenced a drug for gout. The occurrence of gout flare or the need for treatment for gout was lower in participants treated with canagliflozin than in those who received placebo (HR 0·53, 95% CI 0·40-0·71; p<0·0001). The proportional reduction for gout flare adverse events (2·0 patients with an event per 1000 patient-years in the canagliflozin group vs 2·6 patients with an event per 1000 patient-years in the placebo group; 0·64, 95% CI 0·41-0·99; p=0·046) was similar in size to that for commencement of a drug for gout (3·3 vs 5·4 patients with an event per 1000 patient-years; 0·52, 0·38-0·72; p<0·0001) and hyperuricaemia (1·8 vs 2·5 patients with an event per 1000 patient-years; 0·59, 0·37-0·93; p=0·023).

INTERPRETATION

In this post-hoc analysis, compared with placebo, canagliflozin reduced serum urate concentration and also reduced events related to gout flare among patients with type 2 diabetes. A trial explicitly designed to test the effects of sodium glucose co-transporter 2 inhibition on gout is required to confirm these observations.

FUNDING

Janssen Research & Development.

Cardioprotection conferred by sodium-glucose cotransporter 2 inhibitors: a renal proximal tubule perspective

Sodium-glucose cotransporter 2 (SGLT2) inhibitors, also known as gliflozins, improve glycemia by suppressing glucose reuptake in the renal proximal tubule. Currently, SGLT2 inhibitors are primarily indicated as antidiabetic agents; however, their benefits extend far beyond glucose control. Cardiovascular outcome trials indicated that all studied SGLT2 inhibitors remarkably and consistently reduce cardiovascular mortality and hospitalization for heart failure (HF) in type 2 diabetes (T2D) patients. Nevertheless, the mechanisms underlying the unprecedented cardiovascular benefits of gliflozins remain elusive. Multiple processes that directly or indirectly improve myocardial performance may be involved, including the amelioration of proximal tubular dysfunction. Therefore, this paper provides a perspective on the potential cellular and molecular mechanisms of the proximal tubule that may, at least in part, mediate the cardioprotection conferred by SGLT2 inhibitors. Specifically, we focus on the effects of SGLT2 on extracellular volume homeostasis, including its plausible functional and physical association with the apical Na⁺/H⁺ exchanger isoform 3 as well as its complex and its possible bidirectional interactions with the intrarenal angiotensin system and renal sympathetic nervous system. We also discuss evidence supporting a potential benefit of gliflozins in reducing cardiovascular risk, attributable to their effect on proximal tubule handling of uric acid and albumin as well as in erythropoietin production. Unraveling the mechanisms behind the beneficial actions of SGLT2 inhibitors may not only contribute to a better understanding of the pathophysiology of cardiovascular diseases but also enable repurposing of gliflozins to improve the routine management of HF patients with or without T2D.

Mechanisms of Protective Effects of SGLT2 Inhibitors in Cardiovascular Disease and Renal Dysfunction

Type 2 diabetes mellitus is one of the most common forms of the disease worldwide. Hyperglycemia and insulin resistance play key roles in type 2 diabetes mellitus. Renal glucose reabsorption is an essential feature in glycaemic control. Kidneys filter 160 g of glucose daily in healthy subjects under euglycaemic conditions. The expanding epidemic of diabetes leads to a prevalence of diabetes-related cardiovascular disorders, in particular, heart failure and renal dysfunction. Cellular glucose uptake is a fundamental process for homeostasis, growth, and metabolism. In humans, three families of glucose transporters have been identified, including the glucose facilitators GLUTs, the sodium-glucose cotransporter SGLTs, and the recently identified SWEETs. Structures of the major isoforms of all three families were studied. Sodium-glucose cotransporter (SGLT2) provides most of the capacity for renal glucose reabsorption in the early proximal tubule. A number of cardiovascular outcome trials in patients with type 2 diabetes have been studied with SGLT2 inhibitors reducing cardiovascular morbidity and mortality. The current review article summarises these aspects and discusses possible mechanisms with SGLT2 inhibitors in protecting heart failure and renal dysfunction in diabetic patients. Through glucosuria, SGLT2 inhibitors reduce body weight and body fat, and shift substrate utilisation from carbohydrates to lipids and, possibly, ketone bodies. These pleiotropic effects of SGLT2 inhibitors are likely to have contributed to the results of the EMPA-REG OUTCOME trial in which the SGLT2 inhibitor, empagliflozin, slowed down the progression of chronic kidney disease and reduced major adverse cardiovascular events in high-risk individuals with type 2 diabetes. This review discusses the role of SGLT2 in the physiology and pathophysiology of renal glucose reabsorption and outlines the unexpected logic of inhibiting SGLT2 in the diabetic kidney.

Mediators of the Effects of Canagliflozin on Heart Failure in Patients With Type 2 Diabetes

OBJECTIVES

The purpose of this study was to explore potential mediators of the effects of canagliflozin on heart failure in the CANVAS Program (CANagliflozin cardioVascular Assessment Study; NCT01032629 and CANagliflozin cardioVascular Assessment Study-Renal; NCT01989754).

BACKGROUND

Canagliflozin reduced the risk of heart failure among patients with type 2 diabetes in the CANVAS Program. The mechanism of protection is uncertain.

METHODS

The percentages of mediating effects of 19 biomarkers were determined by comparing the hazard ratios for the effect of randomized treatment from an unadjusted model and from a model adjusting for the biomarker of interest. Multivariable analyses were used to assess the joint effects of biomarkers that mediated most strongly in univariable analyses.

RESULTS

Early changes after randomization in levels of 3 biomarkers (urinary albumin:creatinine ratio, serum bicarbonate, and serum urate) were identified as mediating the effect of canagliflozin on heart failure. Average post-randomization levels of 14 biomarkers (systolic blood pressure, low-density lipoprotein and high-density lipoprotein cholesterol, total cholesterol, urinary albumin:creatinine ratio, weight, body mass index, gamma glutamyltransferase, hematocrit, hemoglobin concentration, serum albumin, erythrocyte concentration, serum bicarbonate, and serum urate) were identified as significant mediators. Individually, the 3 biomarkers with the largest mediating effect were erythrocyte concentration (45%), hemoglobin concentration (43%), and serum urate (40%). In a parsimonious multivariable model, erythrocyte concentration, serum urate, and urinary albumin:creatinine ratio were the 3 biomarkers that maximized cumulative mediation (102%).

CONCLUSIONS

A diverse set of potential mediators of the effect of canagliflozin on heart failure were identified. Some mediating effects were anticipated, whereas others were not. The mediators that were identified support existing and novel hypothesized mechanisms for the prevention of heart failure with sodium glucose cotransporter 2 inhibitors.

Decreased Associated Risk of Gout in Diabetes Patients with Uric Acid Urolithiasis

Uric acid urolithiasis constitutes approximately 7–10% of all urinary stones. Previous studies have revealed that patients with gout do not equally have uric acid stones. Instead, the risk of gout in patients with uric acid stones remains controversial. This study aimed to investigate whether there is different associated risk of gout for diabetes mellitus (DM) and non-diabetes patients with uric acid urolithiasis. Therefore, we examined all baseline chemistries to determine any risk factors or protective factors related to developing gout in patients with uric acid stones. Ninety-nine patients from a single medical center, who had a uric acid component in their stone specimen were enrolled and their medical records were reviewed retrospectively between January 2010 and December 2016. All patients were divided into gout and non-gout groups. Gout was confirmed in 24 patients in this study (24.2%). The proportion of DM was significantly higher in the non-gout group (34.7%) than in the gout group (4.3%, p < 0.05). Renal function was decreased and serum triglyceride was higher in patients with gout. Uric acid urolithiasis patients with DM had a lower risk for gout (adjusted odds ratio: 0.08; 95% confidence interval (CI) = 0.01–0.61, p = 0.015). In 89 patients with predominant uric acid stones (>50% uric acid composition), the risk for gout was still lower in patients with diabetes than non-diabetes (adjusted odds ratio: 0.08; 95% confidence interval (CI) = 0.01–0.61, p = 0.015). These findings suggest that decreased risk of gout is found in uric acid urolithiasis patients with diabetes. Our results imply that patients with uric acid stones should have complete diabetes evaluation before the administration of uric acid controlling medication.

Differential pharmacology and clinical utility of dapagliflozin in type 2 diabetes

Dapagliflozin belongs in the family of sodium-glucose cotransporter 2 (SGLT2) inhibitors and acts by reducing glucose reabsorption in the proximal tubule. The aim of this review is to present the differential pharmacology and clinical utility of dapagliflozin. Dapagliflozin is orally administered, has a long half-life of 12.9 hours and (similar to empagliflozin) is a much weaker SGLT1 inhibitor compared with canagliflozin. Dapagliflozin significantly decreases glycated hemoglobin and fasting glucose levels in patients with type 2 diabetes mellitus (T2DM). The drug improves body weight, blood pressure, uric acid, triglycerides and high-density lipoprotein cholesterol. In the DECLARE-TIMI 58 trial, a large trial of 17,160 T2DM patients with established cardiovascular disease (CVD) or without established CVD but with multiple risk factors, dapagliflozin compared with placebo resulted in a significantly lower rate of the composite outcome of CVD death or hospitalization for heart failure (HHF); this effect was mainly due to a lower rate of HHF in the dapagliflozin group (HR: 0.73; 95%CI: 0.61–0.88), whereas no difference was observed in the rate of CVD death (HR: 0.98; 95%CI: 0.82–1.17). Moreover, dapagliflozin was noninferior to placebo with respect to major adverse CVD events. Dapagliflozin exerts beneficial effects on albuminuria. Additionally, in the DECLARE-TIMI 58 trial it significantly reduced the composite renal endpoint (40% decrease in glomerular filtration rate, end stage renal disease, or renal death) in both patients with established CVD and patients with multiple risk factors (overall HR: 0.53; 95%CI: 0.43–0.66). However dapagliflozin, like the other SGLT2 inhibitors, is associated with an increased risk of genital and urinary tract infections (usually mild mycotic infections) and acute kidney injury in cases of reduced extracellular volume. Dapagliflozin is a useful antidiabetic treatment which also exerts beneficial effects in the management of heart failure and diabetic kidney disease.

Sodium-glucose cotransporter 2 inhibitors for diabetic kidney disease: a primer for deprescribing

Chronic kidney disease (CKD) is a critical global public health problem associated with high morbidity and mortality, poorer quality of life and increased health care expenditures. CKD and its associated comorbidities are one of the most complex clinical constellations to manage. Treatments for CKD and its comorbidities lead to polypharmacy, which exponentiates the morbidity and mortality. Sodium-glucose cotransporter 2 inhibitors (SGLT2is) have shown remarkable benefits in cardiovascular and renal protection in patients with type 2 diabetes mellitus (T2DM). The pleiotropic effects of SGLT2is beyond glycosuria suggest a promising role in reducing polypharmacy in diabetic CKD, but the potential adverse effects of SGLT2is should also be considered. In this review, we present a typical case of a patient with multiple comorbidities seen in a CKD clinic, highlighting the polypharmacy and complexity in the management of proteinuria, hyperkalemia, volume overload, hyperuricemia, hypoglycemia and obesity. We review the cardiovascular and renal protection effects of SGLT2is in the context of clinical trials and current guidelines. We then discuss the roles of SGLT2is in the management of associated comorbidities and review the adverse effects and controversies of SGLT2is. We conclude with a proposal for deprescribing principles when initiating SGLT2is in patients with diabetic CKD.

Differences in the association between glycemia and uric acid levels in diabetic and non-diabetic populations

AIMS

Our study aimed to investigate the influence of different glycemic statuses and their fasting plasma glucose/2-hour post-load glucose on uric acid level.

METHODS

A total of 14,787 subjects were recruited after excluding subjects with medication for hyperuricemia or diabetes. Fasting plasma glucose (FPG), 2-hour post-load glucose (2hPG), and uric acid (UA) were measured. Then, subjects were divided into normal glucose tolerance (NGT), impaired fasting glucose (IFG), impaired glucose tolerance (IGT), and diabetes.

RESULTS

After adjustment for clinical variables, in NGT group, there was no significant relationship found between UA level and FPG. However, there was a positive association between UA level and 2hPG (β = 0.003, 95% CI: 0.002~0.004). A similar trend was also observed between UA level and 2hPG in IFG group (β = 0.004, 95% CI: 0.000~0.009) and IGT group (β = 0.005, 95% CI: 0.002~0.008), but relationship between UA level and FPG remained insignificant. In diabetes group, UA level was negatively associated with both FPG (β = -0.008, 95% CI: -0.010 ~ -0.007) and 2hPG (β = -0.005, 95% CI: -0.006 ~-0.003).

CONCLUSIONS

In non-diabetic individuals, UA level increased with 2hPG, but not with FPG, and UA level was inversely associated with both FPG and 2hPG in diabetic population.

The case for uric acid-lowering treatment in patients with hyperuricaemia and CKD

Hyperuricaemia is common among patients with chronic kidney disease (CKD), and increases in severity with the deterioration of kidney function. Although existing guidelines for CKD management do not recommend testing for or treatment of hyperuricaemia in the absence of a diagnosis of gout or urate nephrolithiasis, an emerging body of evidence supports a direct causal relationship between serum urate levels and the development of CKD. Here, we review randomized clinical trials that have evaluated the effect of urate-lowering therapy (ULT) on the rate of CKD progression. Among trials in which individuals in the control arm experienced progressive deterioration of kidney function (which we define as ≥4 ml/min/1.73 m² over the course of the study - typically 6 months to 2 years), treatment with ULT conferred consistent clinical benefits. In contrast, among trials where clinical progression was not observed in the control arm, treatment with ULT was ineffective, but this finding should not be used as an argument against the use of uric acid-lowering therapy. Although additional studies are needed to identify threshold values of serum urate for treatment initiation and to confirm optimal target levels, we believe that sufficient evidence exists to recommend routine measurement of serum urate levels in patients with CKD and consider initiation of ULT among those who are hyperuricaemic with evidence of deteriorating renal function, unless specific contraindications exist.

Increased urinary glucose excretion is associated with a reduced risk of hyperuricaemia

AIM

To investigate the association of urinary glucose excretion with levels of serum uric acid in adults with newly diagnosed diabetes.

METHODS

A total of 597 people with newly diagnosed diabetes, confirmed in an oral glucose tolerance test, were included in the present study. The participants were divided into two groups: 142 participants with low urinary glucose excretion and 455 with high urinary glucose excretion. Demographic characteristics and clinical variables were evaluated. The association of urinary glucose excretion with uric acid was analysed using multivariable regression analysis.

RESULTS

The low urinary glucose excretion group had a significantly higher prevalence of hyperuricaemia than the high urinary glucose excretion group. Moreover, urinary glucose excretion was negatively associated with uric acid level. The correlation remained significant after adjusting for potential confounders, including gender, age, fasting plasma glucose, 2-h plasma glucose and BMI. The results also showed that participants with high urinary glucose excretion were at decreased risk of hyperuricaemia (odds ratio 0.47, 95% CI 0.27-0.80; P = 0.006).

CONCLUSION

Urinary glucose excretion was independently associated with uric acid level in participants with newly diagnosed diabetes. In addition to lowering blood glucose, promoting urinary glucose excretion may also be an effective approach to reducing serum uric acid levels, especially for people with diabetes complicated with hyperuricaemia.

The effect of SGLT-2 inhibitors on blood pressure: a pleiotropic action favoring cardio- and nephroprotection

Strict blood pressure (BP) control in patients with diabetes is associated with reductions in cardiovascular and renal risk. SGLT-2 inhibitors act in the proximal tubule to reduce glucose reabsorption. They also have mild natriuretic and diuretic effects, combining properties of proximal tubule diuretics and osmotic diuretics, which are expected to reduce BP. Several lines of evidence suggests that SGLT-2 inhibitors produce mild but meaningful reductions in BP and also decrease the incidence of renal outcomes, cardiovascular events and mortality. Thus, recent guidelines for type 2 diabetes suggest that among oral agents to use together with metformin, SGLT-2 inhibitors should be preferred in patients at increased cardiovascular risk, kidney disease or heart failure. This review summarizes current literature on the effect of SGLT-2 inhibitors on BP, and its potential relationships with cardio- and nephroprotection.

Sodium-Glucose Cotransporter 2 Inhibitors: A Case Study in Translational Research

Sodium-glucose cotransporter 2 (SGLT2) inhibitors are the most recently approved class of diabetes drugs. Unlike other agents, SGLT2 inhibitors act on the kidney to promote urinary glucose excretion. SGLT2 inhibitors provide multiple benefits, including decreased HbA_1c, body weight, and blood pressure. These drugs have received special attention because they decrease the risk of major adverse cardiovascular events and slow progression of diabetic kidney disease (1-3). Balanced against these impressive benefits, the U.S. Food and Drug Administration-approved prescribing information describes a long list of side effects: genitourinary infections, ketoacidosis, bone fractures, amputations, acute kidney injury, perineal necrotizing fasciitis, and hyperkalemia. This review provides a physiological perspective to understanding the multiple actions of these drugs complemented by a clinical perspective toward balancing benefits and risks.

Association between uric acid, renal haemodynamics and arterial stiffness over the natural history of type 1 diabetes

AIMS

To examine the relationship between normal plasma uric acid (PUA) levels, renal haemodynamic function, arterial stiffness and plasma renin and aldosterone over a wide range of type 1 diabetes (T1D) durations in adolescents, young adults and older adults.

MATERIALS AND METHODS

PUA, glomerular filtration rate (GFR), effective renal plasma flow (ERPF), vascular stiffness parameters (aortic augmentation index [AIx], carotid AIx, carotid femoral pulse wave velocity [cfPWV]), and plasma renin and aldosterone were measured during a euglycaemic clamp in people with T1D: 27 adolescents (mean ± SD age 16.8 ± 1.9 years), 52 young adults (mean ± SD age 25.6 ± 5.5 years) and 66 older adults (mean ± SD age 65.7 ± 7.5 years).

RESULTS

PUA was highest in patients with the longest T1D duration: 197 ± 44 μmol/L in adolescents versus 264 ± 82 μmol/L in older adults (P < 0.001). Higher PUA correlated with lower GFR only in older adults, even after correcting for age, glycated haemoglobin and sex (β = -2.12 ± 0.56; P = 0.0003), but not in adolescents or young adults. Higher PUA correlated with lower carotid AIx (β = -1.90, P = 0.02) in adolescents. In contrast, PUA correlated with higher cfPWV (P = 0.02) and higher plasma renin (P = 0.01) in older adults with T1D.

CONCLUSIONS

The relationship between higher PUA with lower GFR, increased arterial stiffness and renin angiotensin aldosterone system (RAAS) activation was observed only in older adults with longstanding T1D. T1D duration may modify the association between PUA, renal haemodynamic function and RAAS activation, leading to renal vasoconstriction and ischaemia. Further work must determine whether pharmacological PUA-lowering prevents or reverses injurious haemodynamic and neurohormonal sequelae of longstanding T1D, thereby improving clinical outcomes.

Uric acid and the cardio-renal effects of SGLT2 inhibitors

Sodium/glucose co-transporter-2 (SGLT2) inhibitors, which lower blood glucose by increasing renal glucose elimination, have been shown to reduce the risk of adverse cardiovascular (CV) and renal events in type 2 diabetes. This has been ascribed, in part, to haemodynamic changes, body weight reduction and several possible effects on myocardial, endothelial and tubulo-glomerular functions, as well as to reduced glucotoxicity. This review evaluates evidence that an effect of SGLT2 inhibitors to lower uric acid may also contribute to reduced cardio-renal risk. Chronically elevated circulating uric acid concentrations are associated with increased risk of hypertension, CV disease and chronic kidney disease (CKD). The extent to which uric acid contributes to these conditions, either as a cause or an aggravating factor, remains unclear, but interventions that reduce urate production or increase urate excretion in hyperuricaemic patients have consistently improved cardio-renal prognoses. Uric acid concentrations are often elevated in type 2 diabetes, contributing to the "metabolic syndrome" of CV risk. Treating type 2 diabetes with an SGLT2 inhibitor increases uric acid excretion, reduces circulating uric acid and improves parameters of CV and renal function. This raises the possibility that the lowering of uric acid by SGLT2 inhibition may assist in reducing adverse CV events and slowing progression of CKD in type 2 diabetes. SGLT2 inhibition might also be useful in the treatment of gout and gouty arthritis, especially when co-existent with diabetes.

A model of uric acid transport in the rat proximal tubule

The objective of the present study was to theoretically investigate the mechanisms underlying uric acid transport in the proximal tubule (PT) of rat kidneys, and their modulation by factors, including Na+, parathyroid hormone, ANG II, and Na+-glucose cotransporter-2 inhibitors. To that end, we incorporated the transport of uric acid and its conjugate anion urate in our mathematical model of water and solute transport in the rat PT. The model accounts for parallel urate reabsorption and secretion pathways on apical and basolateral membranes and their coupling to lactate and α-ketoglutarate transport. Model results agree with experimental findings at the segment level. Net reabsorption of urate by the rat PT is predicted to be ~70% of the filtered load, with a rate of urate removal from the lumen that is 50% higher than the rate of urate secretion. The model suggests that apical URAT1 deletion significantly reduces net urate reabsorption across the PT, whereas ATP-binding cassette subfamily G member 2 dysfunction affects it only slightly. Inactivation of basolateral glucose transporter-9 raises fractional urate excretion above 100%, as observed in patients with renal familial hypouricemia. Furthermore, our results suggest that reducing Na+ reabsorption across Na+/H+ exchangers or Na+-glucose cotransporters augments net urate reabsorption. The model predicts that parathyroid hormone reduces urate excretion, whereas ANG II increases it. In conclusion, we have developed the first model of uric acid transport in the rat PT; this model provides a framework to gain greater insight into the numerous solutes and coupling mechanisms that affect the renal handing of uric acid.

Changes of drug pharmacokinetics mediated by downregulation of kidney organic cation transporters Mate1 and Oct2 in a rat model of hyperuricemia

The effects of hyperuricemia on the expression of kidney drug transporters and on the pharmacokinetics of several substrate drugs were examined. We first established a rat model of hyperuricemia without marked symptoms of chronic kidney failure by 10-day co-administration of oxonic acid (uricase inhibitor) and adenine (biosynthetic precursor of uric acid). These hyperuricemic rats showed plasma uric acid concentrations of up to 6 mg/dL, which is similar to the serum uric acid level in hyperuricemic humans, with little change of inulin clearance. The mRNA levels of multidrug and toxin extrusion 1 (Mate1, Slc47a1), organic anion transporter 1 (Oat1, Slc22a6), organic cation transporter 2 (Oct2, Slc22a2), urate transporter 1 (Urat1, Slc22a12) and peptide transporter 1 (Pept1, Slc15a1) were significantly decreased in kidney of hyperuricemic rats. Since Oct2, Mate1 and Oat1 are important for renal drug elimination, we next investigated whether the pharmacokinetics of their substrates, metformin, cephalexin and creatinine, were altered. The plasma concentration of metformin was not affected, while its kidney tissue accumulation was significantly increased. The plasma concentration and kidney tissue accumulation of cephalexin and the plasma concentration of creatinine were also increased. Furthermore, the protein expression of kidney Mate1 was decreased in hyperuricemic rats. Accordingly, although multiple factors may influence renal handling of these drugs, these observations can be accounted for, at least in part, by downregulation of Mate1-mediated apical efflux from tubular cells and Oct2-mediated basolateral uptake. Our results suggest that hyperuricemia could alter the disposition of drugs that are substrates of Mate1 and/or Oct2.

A review of the mechanism of action, metabolic profile and haemodynamic effects of sodium-glucose co-transporter-2 inhibitors

Inhibition of glucose transport in the kidney, to produce glucosuria and thus directly lower blood glucose seems a remarkably simple way to treat diabetes (type 1 or type 2). The development of sodium-glucose co-transporter-2 (SGLT2) inhibitors and their subsequent clinical development has on one hand shown this to be true, but at another level has helped reveal a complex web of interacting effects starting in the kidney and modulating multiple metabolic pathways in a variety of other organs. These underlie the now clear benefits of this class of drugs in the management of type 2 diabetes from glucose lowering, weight loss and blood pressure reduction through to the reductions in cardiovascular and renal complications observed in long-term outcomes trials. They also explain some of the adverse effects that have emerged, including the risk of diabetic ketoacidosis. This review describes the effects of SGLT2 inhibition in relation to this complex physiology, and shows how this can favourably alter the pathophysiology of type 2 diabetes.

Evidence-Based Consensus on Positioning of SGLT2i in Type 2 Diabetes Mellitus in Indians

The current diabetes management strategies not only aim at controlling glycaemic parameters but also necessitate continuous medical care along with multifactorial risk reduction through a comprehensive management concept. The sodium-glucose cotransporter 2 inhibitors (SGLT2i) are a group of evolving antidiabetic agents that have the potential to play a pivotal role in the comprehensive management of patients with diabetes due to their diverse beneficial effects. SGLT2i provide moderate glycaemic control, considerable body weight and blood pressure reduction, and thus have the ability to lower the risk of macrovascular and microvascular complications. Some of the unique characteristics associated with SGLT2i, such as reduction in body weight (more visceral fat mass loss than subcutaneous fat loss), reduction in insulin resistance and improvement in β-cell function, as measured by homeostatic model assessment-β (HOMA-β) could be potentially beneficial and help in overcoming some of the challenges faced by Indian patients with diabetes. In addition, a patient-centric approach with individualised treatment during SGLT2i therapy is inevitable in order to reduce diabetic complications and improve quality of life. Despite their broad benefits profile, the risk of genital tract infections, volume depletion, amputations and diabetic ketoacidosis associated with SGLT2i should be carefully monitored. In this compendium, we systematically reviewed the literature from Medline, Cochrane Library, and other relevant databases and attempted to provide evidence-based recommendations for the positioning of SGLT2i in the management of diabetes in the Indian population.Funding: AstraZeneca Pharma India Limited.

SGLT2 inhibitors and cardioprotection: a matter of debate and multiple hypotheses

Sodium-glucose co-transporter 2 (SGLT2) inhibitors inhibit glucose re-absorption in the proximal renal tubules. Two trials have shown significant reductions of cardiovascular (CV) events with empagliflozin and canagliflozin, which could not be attributed solely to their antidiabetic effects. The aim of the review is the critical presentation of suggested mechanisms/hypotheses for the SGLT2 inhibitors' cardioprotection. The search of the literature revealed many possible cardioprotective mechanisms, because SGLT2 inhibitors (i) increase natriuresis and act as diuretics with unique properties leading to a reduction in preload and myocardial stretch (the diuretic hypothesis); (ii) decrease blood pressure and afterload (the blood pressure lowering hypothesis), (iii) favor the production of ketones, which can act as a 'superfuel' in the cardiac and renal tissue (the 'thrifty substrate' hypothesis), (iv) improve many metabolic variables (the metabolic effects hypothesis), (v) exert many anti-inflammatory effects (the anti-inflammatory effects hypothesis), (vi) can act through the angiotensin II type II receptors in the context of simultaneous renin-angiotensin-aldosterone-system (RAAS) blockade leading to vasodilation and positive inotropic effects (the RAAS hypothesis), (vii) directly decrease the activity of the upregulated in heart failure Na⁺-H⁺ exchanger in myocardial cells leading to restoration of mitochondrial calcium handling in cardiomyocytes (the sodium hypothesis). Additionally, some SGLT2 inhibitors exhibit also SGLT1 inhibitory action possibly resulting in an attenuation of oxidative stress in ischemic myocardium (the SGLT1 inhibition hypothesis). Thus, many mechanisms have been suggested (and possibly act cumulatively) for the cardioprotective effects of SGLT2 inhibitors.

Pre-treatment with Empagliflozin ameliorates Cisplatin induced acute kidney injury by suppressing apoptosis

Dose-limiting nephrotoxicity restricts Cisplatin use in high therapeutic doses. Empagliflozin showed a reno-protective effect in diabetic nephropathy. We investigated if Empagliflozin can ameliorate Cisplatin nephrotoxicity whether used prophylactically or therapeutically. Forty male Wistar rats were divided into 5 groups: (1) control; (2) Cisplatin-induced nephrotoxicity by single intraperitoneal dose; (3) Empagliflozin was given for 10 days before a single dose of Cisplatin; (4) a single dose of Cisplatin followed by Empagliflozin for 10 days; (5) received Empagliflozin only. Regular assessment of weight was done, biochemical evaluation for serum urea, creatinine, uric acid, albumin, and glucose was performed, kidney tissue nerve growth factor-β (NGF-β) and oxidative stress parameters were measured, kidneys were evaluated histopathologically and immunostained for caspase 3. Cisplatin significantly reduced body weight, NGF-β, and reduced glutathione, elevated urea, creatinine, and malondialdehyde with no effect on other serum biochemical parameters. Histopathologically, there was high acute tubular necrosis (ATN) score with strong immunostaining of caspase 3. The use of Empagliflozin significantly reduced urea and creatinine in both prophylactic and therapeutic, reduced ATN score in the prophylactic group associated with minimal staining of caspase 3 and elevated reduced glutathione. In conclusion, prophylactic Empagliflozin protected against Cisplatin-induced acute kidney injury mainly via anti-apoptotic effect.