Why Do SGLT2 inhibitors inhibit only 30-50% of renal glucose reabsorption in humans?

A safety update on sodium glucose co-transporter 2 inhibitors

Sodium glucose co-transporter 2 inhibitors (SGLT2is) are the first class of glucose lowering agent to be shown to reduce cardiovascular events. They are generally well tolerated with infrequent serious adverse events. The most frequent side effect is genital mycotic infections with candida species that are usually mild to moderate in severity, easily treated and infrequently recur. Urinary tract infections, although common in patients with diabetes, have not been shown to be increased in controlled studies with SGLT2i. Hypoglycaemia can occur when an SGLT2i is added to agents that cause hypoglycaemia, such as insulin or sulphonylureas. Volume depletion and hypotension is infrequent and can be minimized by adjusting diuretic and antihypertensive treatment in patients at risk. Acute renal failure or kidney injury was observed in early observational studies. However, in randomized controlled trials (RCTs) and in more recent observational studies a decreased incidence of acute kidney injury was observed in SGLT2-treated patients compared to those receiving either placebo or another class of glucose lowering agents. An increased incidence of amputation (largely feet and toes) was observed in the RCT with canagliflozin but not with the other SGLT2i. Observational studies have shown either an increased risk of amputation with other agents whereas another study showed no increase. Although the increased risk of amputation is very low, avoidance of SGLT2i in patients at high risk seems prudent. Increased incidence of fractures was observed with canagliflozin but not with SGLT2i nor in a meta-analysis that included canagliflozin, empagliflozin and dapagliflozin. No increased incidence of cancer has been observed in either RCTs or observational studies.

Direct cardiovascular impact of SGLT2 inhibitors: mechanisms and effects

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

Ion channels and transporters in diabetic kidney disease

Type 1 and 2 diabetes mellitus are major medical epidemics affecting millions of patients worldwide. Diabetes mellitus is the leading cause of diabetic kidney disease (DKD), which is the most common cause of end-stage renal disease (ESRD). DKD is associated with significant changes in renal hemodynamics and electrolyte transport. Alterations in renal ion transport triggered by pathophysiological conditions in diabetes can exacerbate hypertension, accelerate renal injury, and are integral to the development of DKD. Renal ion transporters and electrolyte homeostasis play a fundamental role in functional changes and injury to the kidney during DKD. With the large number of ion transporters involved in DKD, understanding the roles of individual transporters as well as the complex cascades through which they interact is essential in the development of effective treatments for patients suffering from this disease. This chapter aims to gather current knowledge of the major renal ion transporters with altered expression and activity under diabetic conditions, and provide a comprehensive overview of their interactions and collective functions in DKD.

Diuretic Effects of Sodium Glucose Cotransporter 2 Inhibitors and Their Influence on the Renin-Angiotensin System

The renin-angiotensin system (RAS) plays an important role in regulating body fluids and blood pressure. However, inappropriate activation of the RAS contributes to the pathogenesis of cardiovascular and renal diseases. Recently, sodium glucose cotransporter 2 (SGLT2) inhibitors have been used as anti-diabetic agents. SGLT2 inhibitors induce glycosuria and improve hyperglycemia by inhibiting urinary reabsorption of glucose. However, in the early stages of treatment, these inhibitors frequently cause polyuria and natriuresis, which potentially activate the RAS. Nevertheless, the effects of SGLT2 inhibitors on RAS activity are not straightforward. Available data indicate that treatment with SGLT2 inhibitors transiently activates the systemic RAS in type 2 diabetic patients, but not the intrarenal RAS. In this review article, we summarize current evidence of the diuretic effects of SGLT2 inhibitors and their influence on RAS activity.

Adverse Effect Profile and Effectiveness of Sodium Glucose Co-transporter 2 Inhibitors (SGLT2i) - A Prospective Real-world Setting Study

BACKGROUND

Clinical trials have shown promising results in terms of glycemic control and weight reduction with the use of sodium glucose co-transporter 2 inhibitors (SGLT2i) in type 2 diabetes mellitus (T2DM). However, real-world evidence from standard clinical practice especially from Asia is still limited. The aim of this study was to evaluate the safety and effectiveness of SGLT2i in patients with T2DM in real-world setting.

METHODS

This was a prospective observational longitudinal study involving consecutive patients with T2DM, initiated on SGLT2i from 1 April 2015 to 31 March 2016. The adverse effects and metabolic parameters were evaluated at 3 monthly intervals up to 1 year.

RESULTS

Total 486 patients were initiated on SGLT2i. At baseline, mean age, glycosylated haemoglobin (HbA1c), and weight was 51.03 ± 9.82 years, 8.76 ± 1.59%, and 89.32 ± 16.04 kg, respectively. Data of 388 patients were available at 6 months of follow-up for analysis of adverse effects profile. About 38.6% patients experienced adverse effects. Genitourinary tract infection was the most common adverse effect (20.6%) followed by generalized weakness (10.5%). Significant reduction in mean weight and HbA1c reduction seen at 6 months (n = 202): 3.2 kg and 1.26%, respectively, and at 12 months (n = 104): 3.9 kg and 1.27%, respectively.

CONCLUSION

In this real-world study of patients with T2DM living in hot climate, use of SGLT2i was associated with adverse effects in higher proportion of patients than those reported in clinical trials, but effectiveness was comparable. Patient guidance regarding adequate hydration and hygiene can maximize the benefits of this promising class of drugs.

Hormonal, Metabolic and Hemodynamic Adaptations to Glycosuria in Type 2 Diabetes Patients Treated with Sodium-Glucose Co-Transporter Inhibitors

BACKGROUND & INTRODUCTION

The advent of the sodium-glucose cotransporter-2 inhibitors [SGLT-2i] provides an additional tool to combat diabetes and complications. The use of SGLT-2i leads to effective and durable glycemic control with important reductions in body weight/fat and blood pressure. These agents may delay beta-cell deterioration and improve tissue insulin sensitivity, which might slow the progression of the disease.

METHODS & RESULTS

In response to glycosuria, a compensatory rise in endogenous glucose production, sustained by a decrease in plasma insulin with an increase in glucagon has been described. Other possible mediators have been implicated and preliminary findings suggest that a sympathoadrenal discharge and/or rapid elevation in circulating substrates (i.e., fatty acids) or some yet unidentified humoral factors may have a role in a renal-hepatic inter-organ relationship. A possible contribution of enhanced renal gluconeogenesis to glucose entry into the systemic circulation has not yet been ruled out. Additionally, tissue glucose utilization decreases, whereas adipose tissue lipolysis is stimulated and, there is a switch to lipid oxidation with the formation of ketone bodies; the risk for keto-acidosis may limit the use of SGLT-2i. These metabolic adaptations are part of a counter-regulatory response to avoid hypoglycemia and, as a result, limit the SGLT-2i therapeutic efficacy. Recent trials revealed important cardiovascular [CV] beneficial effects of SGLT-2i drugs when used in T2DM patients with CV disease. Although the underlying mechanisms are not fully understood, there appears to be "class effect". Changes in hemodynamics and electrolyte/body fluid distribution are likely involved, but there is no evidence for anti-atherosclerotic effects.

CONCLUSION

It is anticipated that, by providing durable diabetes control and reducing CV morbidity and mortality, the SGLT-2i class of drugs is destined to become a priority choice in diabetes management.

Pharmacological evaluation of HM41322, a novel SGLT1/2 dual inhibitor, in vitro and in vivo

HM41322 is a novel oral sodium-glucose cotransporter (SGLT) 1/2 dual inhibitor. In this study, the in vitro and in vivo pharmacokinetic and pharmacologic profiles of HM41322 were compared to those of dapagliflozin. HM41322 showed a 10-fold selectivity for SGLT2 over SGLT1. HM41322 showed an inhibitory effect on SGLT2 similar to dapagliflozin, but showed a more potent inhibitory effect on SGLT1 than dapagliflozin. The maximum plasma HM41322 level after single oral doses at 0.1, 1, and 3 mg/kg were 142, 439, and 1830 ng/ml, respectively, and the T_1/2 was 3.1 h. HM41322 was rapidly absorbed and reached the circulation within 15 min. HM41322 maximized urinary glucose excretion by inhibiting both SGLT1 and SGLT2 in the kidney. HM41322 3 mg/kg caused the maximum urinary glucose excretion in normoglycemic mice (19.32±1.16 mg/g) at 24 h. In normal and diabetic mice, HM41322 significantly reduced glucose excursion. Four-week administration of HM41322 in db/db mice reduced HbA1c in a dose dependent manner. Taken together, HM41322 showed a favorable preclinical profile of postprandial glucose control through dual inhibitory activities against SGLT1 and SGLT2.

The potential for improving cardio-renal outcomes by sodium-glucose co-transporter-2 inhibition in people with chronic kidney disease: a rationale for the EMPA-KIDNEY study

Diabetes is a common cause of chronic kidney disease (CKD), but in aggregate, non-diabetic diseases account for a higher proportion of cases of CKD than diabetes in many parts of the world. Inhibition of the renin–angiotensin system reduces the risk of kidney disease progression and treatments that lower blood pressure (BP) or low-density lipoprotein cholesterol reduce cardiovascular (CV) risk in this population. Nevertheless, despite such interventions, considerable risks for kidney and CV complications remain. Recently, large placebo-controlled outcome trials have shown that sodium-glucose co-transporter-2 (SGLT-2) inhibitors reduce the risk of CV disease (including CV death and hospitalization for heart failure) in people with type 2 diabetes who are at high risk of atherosclerotic disease, and these effects were largely independent of improvements in hyperglycaemia, BP and body weight. In the kidney, increased sodium delivery to the macula densa mediated by SGLT-2 inhibition has the potential to reduce intraglomerular pressure, which may explain why SGLT-2 inhibitors reduce albuminuria and appear to slow kidney function decline in people with diabetes. Importantly, in the trials completed to date, these benefits appeared to be maintained at lower levels of kidney function, despite attenuation of glycosuric effects, and did not appear to be dependent on ambient hyperglycaemia. There is therefore a rationale for studying the cardio-renal effects of SGLT-2 inhibition in people at risk of CV disease and hyperfiltration (i.e. those with substantially reduced nephron mass and/or albuminuria), irrespective of whether they have diabetes.

A review of clinical trials: mesenchymal stem cell transplant therapy in type 1 and type 2 diabetes mellitus

Type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) are widely prevalent metabolic diseases with differing pathologies. T1DM manifests due to autoimmune destruction of the pancreatic beta cells, resulting in a diminished secretion of insulin. T2DM originates from a state of insulin resistance, resulting in hyperglycemia and reduction in beta cell mass. Both diseases can cause severe health consequences. Despite the globally increasing prevalence of both T1DM and T2DM there remains to be a medically defined cure for either of these diseases. Recently, mesenchymal stem cells (MSCs) have been proposed as a possible curative treatment method. In this review, we explain the molecular mechanisms underlying MSCs and their potential ability to treat T1DM and T2DM. We describe the capability of MSCs to differentiate into insulin-producing cells and regenerate pancreatic beta cells, as well as assess their role in modulating the immune system. Lastly, we evaluate the current literature focusing on the clinical application of MSC transplantation in T1DM and T2DM. Despite the favorable results, study designs and analyses cast doubt on the effectiveness of MSCs for the management of T1DM. Conversely, the positive metabolic effects consistently demonstrated in the literature offer hope for MSCs as a treatment for T2DM, at least in the short-term.

Sodium-Glucose Cotransporter-2 (SGLT-2) Inhibitors and the Treatment of Type 2 Diabetes

Clinical studies evaluating the cardiovascular safety/impact of sodium-glucose cotransporter-2 (SGLT-2) inhibitors demonstrated a reduction in major adverse cardiovascular events driven primarily by a reduced cardiovascular mortality in individuals with type 2 diabetes and previous cardiovascular disease. These somewhat unexpected results are coupled with SGLT-2 inhibitors' known acute effect of improvement in glycemia, reduction in blood pressure, and weight loss. In this review, we summarize the mechanism of action of SGLT-2 inhibitors, the metabolic effects of this class of medication, and the remarkable results of cardiovascular safety trials. In addition, we discuss adverse effects associated with these medications and the current recommendations for the use of these agents in the management of diabetes.

Empagliflozin and Cardio-renal Outcomes in Patients with Type 2 Diabetes and Cardiovascular Disease - Implications for Clinical Practice

In patients with type 2 diabetes (T2D), the excretion of glucose by the kidney with sodium-glucose cotransporter 2 (SGLT2) inhibitors lowers glycosylated haemoglobin (HbA1c) levels, decreases body weight and visceral adiposity, as well as improving cardio-renal haemodynamics. Currently, four SGLT2 inhibitors are approved in the US and Europe to improve glycaemic control - empagliflozin, dapagliflozin, canagliflozin, and ertuglifozin. Recently, the SGLT2 inhibitor empagliflozin was approved by the FDA for the reduction of cardiovascular (CV) death in adults with T2D and CV disease (CVD). This approval was based on the findings of the Empagliflozin, Cardiovascular Outcomes, and Mortality in Type 2 Diabetes (EMPA-REG OUTCOME) study, which was the first study to show a significant reduction of a primary CV endpoint with a glucose-lowering agent. In this study, the primary outcome (CV mortality, non-fatal myocardial infarction [MI] and non-fatal stroke) was reduced by empagliflozin (10.5%; 490/4,687) compared with placebo (12.1%; 282/2,333); hazard ratio (HR), 0.86 (95% confidence interval [CI]: 0.74, 0.99). The primary outcome was driven by a large reduction of CV mortality (relative risk reduction [RRR], 38%). Empagliflozin also reduced all-cause mortality (RRR, 32%). Furthermore, empagliflozin reduced the adjudicated outcome of heart failure (HF) hospitalisation by 35% (HR, 0.65; 95% CI: 0.50, 0.85). Other non-adjudicated measures of HF outcomes were similarly reduced including investigator reported HF, the introduction of loop diuretics and death from HF. In the analysis of renal outcomes, incident or worsening nephropathy was reduced for empagliflozin (12.7%) compared with placebo (18.8%); HR, 0.61 (95% CI: 0.53, 0.70). Empagliflozin significantly reduced the risk of progression to macroalbuminuria (38%) and doubling of creatinine (44%), as well as the need of starting renal-replacement therapy (55%). The benefits of empagliflozin for the reduction of CV death, all-cause death and hospitalisation for HF were observed across a range of baseline subgroups such as HbA1c level and renal function (down to estimated glomerular filtration rate [eGFR] 30 ml/min/1.73 m2). The rapid reduction of HF outcomes with empagliflozin is observed across the spectrum of CVD and HF risk and represents a therapeutic advance in the prevention and perhaps also in the treatment of HF, an often poorly recognised complication of T2D. This review discusses the EMPA-REG OUTCOME study and the implications for treating patients with T2D and CVD.

Association Between Sodium-Glucose Cotransporter 2 Inhibitors and Lower Extremity Amputation Among Patients With Type 2 Diabetes

IMPORTANCE

Results of clinical trials suggest that canagliflozin, a sodium-glucose cotransporter 2 (SGLT-2) inhibitor for treating type 2 diabetes, may be associated with lower extremity amputation.

OBJECTIVE

To quantify the association between the use of oral medication for type 2 diabetes and 5 outcomes (lower extremity amputation, peripheral arterial disease, critical limb ischemia, osteomyelitis, and ulcer).

DESIGN, SETTING, AND PARTICIPANTS

A retrospective cohort study was conducted using Truven Health MarketScan Commercial Claims and Encounters data on new users between September 1, 2012, and September 30, 2015. The study focused on 2.0 million commercially insured individuals and used propensity score weighting to balance baseline differences among groups. Sensitivity analyses varied statistical models, assessed the effect of combining dipeptidyl peptidase 4 (DPP-4) inhibitors and glucagon-like peptide 1 (GLP-1) agonists as a single referent group, adjusted for baseline use of older oral agents, and included people with baseline amputation.

EXPOSURES

New use of SGLT-2 inhibitors alone, DPP-4 inhibitors alone, GLP-1 agonists alone, or other antidiabetic agents (sulfonylurea, metformin hydrochloride, or thiazolidinediones).

MAIN OUTCOMES AND MEASURES

Foot and leg amputation, defined by validated International Classification of Diseases, Ninth Revision and Current Procedural Terminology codes.

RESULTS

Among 2.0 million potentially eligible individuals, a total of 953 906 (516 046 women and 437 860 men; mean [SD] age, 51.8 [10.9] years) were included in the final analyses, including 39 869 new users of SGLT-2 inhibitors (4.2%), 105 023 new users of DPP-4 inhibitors (11.0%), and 39 120 new users of GLP-1 agonists (4.1%). The median observation time ranged from 99 days for new users of GLP-1 agonists to 127 days for those using metformin, sulfonylureas, and thiazolidinediones, while the crude incident rates ranged from 4.90 per 10 000 person-years for those using metformin, sulfonylureas, and thiazolidinediones to 10.53 per 10 000 person-years for new users of SGLT-2 inhibitors. After propensity score weighting and adjustment for demographics, severity of diabetes, comorbidities, and medications, there was a nonstatistically significant increased risk of amputation associated with new use of SGLT-2 inhibitors compared with DPP-4 inhibitors (adjusted hazard ratio, 1.50; 95% CI, 0.85-2.67) and GLP-1 agonists (adjusted hazard ratio, 1.47; 95% CI, 0.64-3.36). New use of SGLT-2 inhibitors was statistically significantly associated with amputation compared with sulfonylureas, metformin, or thiazolidinediones (adjusted hazard ratio, 2.12; 95% CI, 1.19-3.77). These results persisted in sensitivity analyses.

CONCLUSIONS AND RELEVANCE

Use of SGLT-2 inhibitors may be associated with increased risk of amputation compared with some oral treatments for type 2 diabetes. Further observational studies are needed with extended follow-up and larger sample sizes.

Sotagliflozin: a dual sodium-glucose co-transporter-1 and -2 inhibitor for the management of Type 1 and Type 2 diabetes mellitus

AIMS

To evaluate the evidence for the novel dual sodium-glucose co-transporter-1 (SGLT1) and -2 (SGLT2) inhibitor, sotagliflozin, which may enhance the efficacy of SGLT2 inhibitors by additionally reducing intestinal glucose absorption.

METHODS

The search terms 'sotagliflozin', 'LX4211', 'SGLT' and 'diabetes' were entered into PubMed. Evidence for the pharmacokinetics, pharmacodynamics, safety and efficacy of sotagliflozin in Type 1 and 2 diabetes was extracted from the retrieved literature, critically evaluated, and contextualized in relation to data on existing SGLT2 inhibitors.

RESULTS

There is convincing evidence from a range of phase II and III clinical trials that sotagliflozin significantly improves glycaemic control in both Type 1 and Type 2 diabetes. Additional benefits, such as smaller postprandial plasma glucose excursions, lower insulin requirements, appetite suppression and weight loss have been documented. While this is encouraging, several safety concerns remain; a dose-dependent increase in the rate of diabetic ketoacidosis, diarrhoea and genital mycotic infection is apparent, although statistical exploration of the data regarding such events is currently lacking. Speculatively, use of a 200-mg rather than a 400-mg dose may help to limit unwanted effects.

CONCLUSIONS

The current evidence for sotagliflozin in diabetes appears promising. Further studies sufficiently powered to assess present and emerging safety concerns, as well as to identify individuals for whom sotagliflozin may be of particular benefit/harm would now be informative for regulatory decision-making. Direct comparisons with existing SGLT2 inhibitors are also needed to determine relative safety/efficacy profiles for the different indications.

Renal protection by sodium-glucose cotransporter 2 inhibitors and its underlying mechanisms in diabetic kidney disease

AIM

Diabetic kidney disease (DKD) is the most frequent cause of mortality and morbidity, leading a global health burden. This review will focus on the potential therapeutic interventions using Sodium-glucose cotransporter-2 (SGLT2) inhibitors that could prevent the development and progression of DKD.

RESULTS

SGLT2 inhibitors have been widely used as anti-diabetic drugs. Recent clinical studies have demonstrated that these drugs, which improve glycemic control and hypertension and decrease body weight, decrease the risk of renal function impairment and heart failure in patients with type 2 diabetes. With regard to long-term clinical outcomes, the Empagliflozin, Cardiovascular Outcomes, and Mortality in Type 2 Diabetes (EMPA-REG OUTCOME), the EMPA-REG Renal OUTCOME, and the CANagliflozin cardioVascular Assessment Study (CANVAS) program which have been integrated from CANVAS and CANVAS-Renal (CANVAS-R) trials reported significant risk reductions in primary combined major adverse cardiovascular events. Furthermore, regarding renal outcomes, the EMPA-REG Renal OUTCOME and CANVAS program clearly showed improvements in renal outcomes, including decreases in albuminuria and progression of nephropathy, doubling of serum creatinine levels, and initiation of renal replacement therapy.

CONCLUSIONS

Potential mechanisms of SGLT2 inhibitors related to renoprotection can be divided into two categories: hemodynamic actions and metabolic actions.

Molecular Mechanisms Underlying the Cardiovascular Benefits of SGLT2i and GLP-1RA

PURPOSE OF REVIEW

In addition to their effects on glycemic control, two specific classes of relatively new anti-diabetic drugs, namely the sodium glucose co-transporter-2 inhibitors (SGLT2i) and glucagon-like peptide-1 receptor agonists (GLP-1RA) have demonstrated reduced rates of major adverse cardiovascular events (MACE) in subjects with type 2 diabetes (T2D) at high risk for cardiovascular disease (CVD). This review summarizes recent experimental results that inform putative molecular mechanisms underlying these benefits.

RECENT FINDINGS

SGLT2i and GLP-1RA exert cardiovascular effects by targeting in both common and distinctive ways (A) several mediators of macro- and microvascular pathophysiology: namely (A1) inflammation and atherogenesis, (A2) oxidative stress-induced endothelial dysfunction, (A3) vascular smooth muscle cell reactive oxygen species (ROS) production and proliferation, and (A4) thrombosis. These agents also exhibit (B) hemodynamic effects through modulation of (B1) natriuresis/diuresis and (B2) the renin-angiotensin-aldosterone system. This review highlights that while GLP-1RA exert direct effects on vascular (endothelial and smooth muscle) cells, the effects of SGLT2i appear to include the activation of signaling pathways that prevent adverse vascular remodeling. Both SGLT2i and GLP-1RA confer hemodynamic effects that counter adverse cardiac remodeling.

Do effects of sodium-glucose cotransporter-2 inhibitors in patients with diabetes give insight into potential use in non-diabetic kidney disease?

PURPOSE OF REVIEW

Our aim was to review the rationale for the role of sodium-glucose cotransporter-2 inhibitors (SGLT-2i) as renoprotective therapy in patients with and without diabetes.

RECENT FINDINGS

SGLT-2i are antihyperglycemic agents, approved for treating type 2 diabetes to reduce glycosylated hemoglobin, type A1c. Primary glucoregulatory effects occur through selective inhibition of SGLT-2 at the renal proximal tubule promoting glucosuria leading to blood glucose lowering. From a hemodynamic perspective, SGLT-2 inhibition is also associated with decreased glomerular hyperfiltration, an effect that is mediated through natriuresis and tubuloglomerular feedback. With renal injury and progressive nephron loss, diabetic kidney disease, and nondiabetic chronic kidney diseases share overlapping phenotypes exhibiting single nephron hyperfiltration, along with increased proteinuria. Importantly, the impact of SGLT-2 inhibition on renal and systemic hemodynamic function, including effects on lowering blood pressure, hyperfiltration, and plasma volume, are independent of blood glucose lowering and instead are because of natriuresis. Accordingly, large clinical trials with SGLT-2i investigating the potential use of SGLT-2i in patients without diabetes are now underway.

SUMMARY

Based on prominent nonglycemic effects, the clinical use of SGLT-2i as renoprotective therapy may extend to nondiabetic chronic kidney diseases subtypes, which could help to address a large, unmet clinical need.

Empagliflozin Induces Transient Diuresis Without Changing Long-Term Overall Fluid Balance in Japanese Patients With Type 2 Diabetes

INTRODUCTION

Empagliflozin, a sodium glucose co-transporter 2 (SGLT2) inhibitor, ameliorates hyperglycemia in patients with type 2 diabetes (T2D) by inducing sustained glucosuria. Empagliflozin treatment was previously associated with a transient increase in 24-h urine volume in Caucasian patients with T2D, however comparable evidence in Japanese T2D individuals is scarce. We therefore assessed acute and chronic changes in 24-h urine volume and fluid intake with empagliflozin in Japanese patients with T2D.

METHODS

In this randomized, double-blind, placebo-controlled, parallel-group, multiple-dose, 4-week trial, 100 Japanese patients with T2D were randomized to receive either 1, 5, 10, or 25 mg empagliflozin or placebo once-daily. Changes from baseline in 24-h urine volume and fluid intake were assessed at days 1, 27, and 28 after the initiation of empagliflozin.

RESULTS

The 24-h urine volume and fluid intake were comparable across all treatment groups at baseline. Patients treated with either 10 or 25 mg empagliflozin (i.e., the licensed doses in Japan) showed a significant increase in 24-h urine volume compared to placebo at day 1 (mean change from baseline: + 0.83, + 1.08, and + 0.29 L/day in the empagliflozin 10 and 25 mg groups and the placebo group, respectively; both p < 0.001 vs. placebo). However, 24-h urine volume levels in the empagliflozin groups were comparable to placebo at day 27 and 28 (differences vs placebo < 0.1 L/day; p > 0.05). The 24-h fluid intake was comparable across all study groups throughout the entire study period. No events consistent with dehydration were reported during empagliflozin treatment.

CONCLUSION

Treatment initiation with empagliflozin in Japanese patients with T2D was associated with transient diuresis; however, overall urine volume returned towards baseline levels within 4 weeks of treatment. These findings are consistent with a physiological, adaptive mechanism of the kidney to maintain overall body fluid balance in response to treatment initiation with a SGLT2 inhibitor.

TRIAL REGISTRATION NUMBER

NCT00885118.

FUNDING

Nippon Boehringer Ingelheim Co., Ltd.

New Diabetes Therapies and Diabetic Kidney Disease Progression: the Role of SGLT-2 Inhibitors

PURPOSE OF REVIEW

Sodium-glucose co-transporter 2 (SGLT-2) inhibitors have emerged as a promising drug class for the treatment of diabetic kidney disease. Developed originally as glucose-lowering drugs by enhancing urinary glucose excretion, these drugs also lower many other renal and cardiovascular risk factors such as body weight, blood pressure, albuminuria, and uric acid. Results from the EMPA-REG OUTCOME and CANVAS trials show that these salutary effects translate into a reduction in cardiovascular outcomes and have the potential to delay the progression of kidney function decline. This review summarizes recent studies on the mechanisms and rationale of renoprotective effects.

RECENT FINDINGS

Effects of SGLT-2 inhibitors on the kidney are likely explained by multiple pathways. SGLT-2 inhibitors may improve renal oxygenation and intra-renal inflammation thereby slowing the progression of kidney function decline. Additionally, SGLT-2 inhibitors are associated with a reduction in glomerular hyperfiltration, an effect which is mediated through increased natriuresis and tubuloglomerular feedback and independent of glycemic control. Analogous to diabetic kidney disease, various etiologies of non-diabetic kidney disease are also characterized by single nephron hyperfiltration and elevated albuminuria. This offers the opportunity to reposition SGLT-2 inhibitors from diabetic to non-diabetic kidney disease. Clinical trials are currently ongoing to characterize the efficacy and safety of SGLT-2 inhibitors in patients with diabetic and non-diabetic kidney disease. The glucose-independent hemodynamic mechanisms of SGLT-2 inhibitors provide the possibility to extend the use of SGLT-2 inhibitors to non-diabetic kidney disease. Ongoing dedicated trials have the potential to change clinical practice and outlook of high-risk patients with diabetic (and non-diabetic) kidney disease.

Canagliflozin, dapagliflozin and empagliflozin monotherapy for treating type 2 diabetes: systematic review and economic evaluation

BACKGROUND

Most people with type 2 diabetes are overweight, so initial treatment is aimed at reducing weight and increasing physical activity. Even modest weight loss can improve control of blood glucose. If drug treatment is necessary, the drug of first choice is metformin. However, some people cannot tolerate metformin, which causes diarrhoea in about 10%, and it cannot be used in people with renal impairment. This review appraises three of the newest class of drugs for monotherapy when metformin cannot be used, the sodium-glucose co-transporter 2 (SGLT2) inhibitors.

OBJECTIVE

To review the clinical effectiveness and cost-effectiveness of dapagliflozin (Farxiga, Bristol-Myers Squibb, Luton, UK), canagliflozin (Invokana, Janssen, High Wycombe, UK) and empagliflozin (Jardiance, Merck & Co., Darmstadt, Germany), in monotherapy in people who cannot take metformin.

SOURCES

MEDLINE (1946 to February 2015) and EMBASE (1974 to February 2015) for randomised controlled trials lasting 24 weeks or more. For adverse events, a wider range of studies was used. Three manufacturers provided submissions.

METHODS

Systematic review and economic evaluation. A network meta-analysis was carried out involving the three SGLT2 inhibitors and key comparators. Critical appraisal of submissions from three manufacturers.

RESULTS

We included three trials of dapagliflozin and two each for canagliflozin and empagliflozin. The trials were of good quality. The canagliflozin and dapagliflozin trials compared them with placebo, but the two empagliflozin trials included active comparators. All three drugs were shown to be effective in improving glycaemic control, promoting weight loss and lowering blood pressure (BP).

LIMITATIONS

There were no head-to-head trials of the different flozins, and no long-term data on cardiovascular outcomes in this group of patients. Most trials were against placebo. The trials were done in patient groups that were not always comparable, for example in baseline glycated haemoglobin or body mass index. Data on elderly patients were lacking.

CONCLUSIONS

Dapagliflozin, canagliflozin and empagliflozin are effective in improving glycaemic control, with added benefits of some reductions in BP and weight. Adverse effects are urinary and genital tract infections in a small proportion of users. In monotherapy, the three drugs do not appear cost-effective compared with gliclazide or pioglitazone, but may be competitive against sitagliptin (Januvia, Boehringer Ingelheim, Bracknell, UK).

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

SGLT1 and SGLT1 Inhibitors: A Role to Be Assessed in the Current Clinical Practice

Diabetes is a complex disease of increasingly common occurrence worldwide. Attaining optimal glycemic control is the main challenge to prevent the development of diabetes-related complications and/or to stop their progression. In recent years, the pharmacologic toolkit for the treatment of diabetes has considerably expanded, thus paving the way to more pathophysiology-oriented therapies. For instance, the sodium-glucose cotransporters SGLT2 and SGLT1 have been in the spotlight because of better knowledge of their physiology and therapeutic potential. At present, whereas the SGLT2 inhibitors are widely applied in current clinical practice as an effective and well-tolerated treatment that increases the urinary excretion of glucose, less is known about the use of SGLT1 inhibitors. SGLT1s are of primary importance in the small intestine, an organ that does not express SGLT2, while in the kidney they are expressed in the late renal proximal tubules, where it reabsorbs the glucose escaped from the upstream SGLT2. Hence, SGLT1-mediated glucose reabsorption in the kidney is increased when the tubular glucose load overwhelms the capacity of SGLT2 or when the latter is inhibited. The role of SGLT1 in intestinal and renal glucose transport makes the transporter a potential target for antidiabetic therapy. Here, we briefly report the evidence on LX2761, a new inhibitor against SGLT1 and SGLT2 in vitro, which acts in vivo as a selective inhibitor of SGLT1 in the gastrointestinal tract. LX2761 improves glycemic control without the glycosuria-related side effects of SGLT2 inhibitors, particularly genitourinary tract infections. However, whether it represents a valid therapeutic option for all patients with diabetes or is more appropriate for specific phenotypes, e.g., patients with concomitant diabetes and chronic kidney disease, who may benefit less from the renal mechanism of selective SGLT2 inhibitors, remains to be tested in large randomized controlled trials.

Sodium Glucose Cotransporter-2 Inhibition in Heart Failure: Potential Mechanisms, Clinical Applications, and Summary of Clinical Trials

Despite current established therapy, heart failure (HF) remains a leading cause of hospitalization and mortality worldwide. Novel therapeutic targets are therefore needed to improve the prognosis of patients with HF. The EMPA-REG OUTCOME trial ([Empagliflozin] Cardiovascular Outcome Event Trial in Type 2 Diabetes Mellitus Patients) demonstrated significant reductions in mortality and HF hospitalization risk in patients with type 2 diabetes mellitus (T2D) and cardiovascular disease with the antihyperglycemic agent, empagliflozin, a sodium glucose cotransporter 2 (SGLT2) inhibitor. The CANVAS trial (Canagliflozin Cardiovascular Assessment Study) subsequently reported a reduction in 3-point major adverse cardiovascular events and HF hospitalization risk. Although SGLT2 inhibition may have potential application beyond T2D, including HF, the mechanisms responsible for the cardioprotective effects of SGLT2 inhibitors remain incompletely understood. SGLT2 inhibition promotes natriuresis and osmotic diuresis, leading to plasma volume contraction and reduced preload, and decreases in blood pressure, arterial stiffness, and afterload as well, thereby improving subendocardial blood flow in patients with HF. SGLT2 inhibition is also associated with preservation of renal function. Based on data from mechanistic studies and clinical trials, large clinical trials with SGLT2 inhibitors are now investigating the potential use of SGLT2 inhibition in patients who have HF with and without T2D. Accordingly, in this review, we summarize the key pharmacodynamic effects of SGLT2 inhibitors and the clinical evidence that support the rationale for the use of SGLT2 inhibitors in patients with HF who have T2D. Because these favorable effects presumably occur independent of blood glucose lowering, we also explore the potential use of SGLT2 inhibition in patients without T2D with HF or at risk of HF, such as in patients with coronary artery disease or hypertension. Finally, we provide a detailed overview and summary of ongoing cardiovascular outcome trials with SGLT2 inhibitors.

Development of a microphysiological model of human kidney proximal tubule function

The kidney proximal tubule is the primary site in the nephron for excretion of waste products through a combination of active uptake and secretory processes and is also a primary target of drug-induced nephrotoxicity. Here, we describe the development and functional characterization of a 3-dimensional flow-directed human kidney proximal tubule microphysiological system. The system replicates the polarity of the proximal tubule, expresses appropriate marker proteins, exhibits biochemical and synthetic activities, as well as secretory and reabsorptive processes associated with proximal tubule function in vivo. This microphysiological system can serve as an ideal platform for ex vivo modeling of renal drug clearance and drug-induced nephrotoxicity. Additionally, this novel system can be used for preclinical screening of new chemical compounds prior to initiating human clinical trials.

Sodium-glucose co-transporter (SGLT) and glucose transporter (GLUT) expression in the kidney of type 2 diabetic subjects

The sodium-glucose co-transporters (SGLTs) are responsible for the tubular reabsorption of filtered glucose from the kidney into the bloodstream. The inhibition of SGLT2-mediated glucose reabsorption is a novel and highly effective strategy to alleviate hyperglycaemia in patients with type 2 diabetes mellitus (T2DM). However, the effectiveness of SGLT2 inhibitor therapy is diminished due, in part, to a compensatory increase in the maximum reabsorptive capacity (Tm) for glucose in patients with T2DM. We hypothesized that this increase in Tm could be explained by an increase in the tubular expression of SGLT and glucose transporters (GLUT) in these patients. To examine this, we obtained human kidney biopsy specimens from patients with or without T2DM and examined the mRNA expression of SGLTs and GLUTs. The expression of SGLT1 is markedly increased in the kidney of patients with T2DM, and SGLT1 mRNA is highly and significantly correlated with fasting and postprandial plasma glucose and HbA1c. In contrast, our data demonstrate that the levels of SGLT2 and GLUT2 mRNA are downregulated in diabetic patients, but not to a statistically significant level. These important findings are clinically significant and may have implications for the treatment of T2DM using strategies that target SGLT transporters in the kidney.

A single dose of dapagliflozin, an SGLT-2 inhibitor, induces higher glycosuria in GCK- and HNF1A-MODY than in type 2 diabetes mellitus

AIMS

SGLT2 inhibitors are a new class of oral hypoglycemic agents used in type 2 diabetes (T2DM). Their effectiveness in maturity onset diabetes of the young (MODY) is unknown. We aimed to assess the response to a single dose of 10 mg dapagliflozin in patients with Hepatocyte Nuclear Factor 1 Alpha (HNF1A)-MODY, Glucokinase (GCK)-MODY, and type 2 diabetes.

METHODS

We examined 14 HNF1A-MODY, 19 GCK-MODY, and 12 type 2 diabetes patients. All studied individuals received a single morning dose of 10 mg of dapagliflozin added to their current therapy of diabetes. To assess the response to dapagliflozin we analyzed change in urinary glucose to creatinine ratio and serum 1,5-Anhydroglucitol (1,5-AG) level.

RESULTS

There were only four patients with positive urine glucose before dapagliflozin administration (one with HNF1A-MODY, two with GCK-MODY, and one with T2DM), whereas after SGLT-2 inhibitor use, glycosuria occurred in all studied participants. Considerable changes in mean glucose to creatinine ratio after dapagliflozin administration were observed in all three groups (20.51 ± 12.08, 23.19 ± 8.10, and 9.84 ± 6.68 mmol/mmol for HNF1A-MODY, GCK-MODY, and T2DM, respectively, p < 0.001 for all comparisons). Post-hoc analysis revealed significant differences in mean glucose to creatinine ratio change between type 2 diabetes and each monogenic diabetes in response to dapagliflozin (p = 0.02, p = 0.003 for HNF1-A and GCK MODY, respectively), but not between the two MODY forms (p = 0.7231). Significant change in serum 1,5-AG was noticed only in T2DM and it was -6.57 ± 7.34 mg/ml (p = 0.04).

CONCLUSIONS

A single dose of dapagliflozin, an SGLT-2 inhibitor, induces higher glycosuria in GCK- and HNF1A-MODY than in T2DM. Whether flozins are a valid therapeutic option in these forms of MODY requires long-term clinical studies.

The roles of sodium-glucose cotransporter 2 inhibitors in preventing kidney injury in diabetes

Diabetic nephropathy (DN) is the leading cause of end stage renal disease (ESRD) worldwide. The early effective treatment of high plasma glucose could delay or prevent the onset of DN. Sodium-glucose cotransporter 2 (SGLT2) inhibitors are new target treatments for ameliorating high plasma glucose and help to maintain glucose homeostasis in diabetic patients. Reduced renal glucose reabsorption by SGLT2 inhibition seems to have high potential to improve glycemic control in diabetes mellitus (DM) not only through glucose lowering but also through glucose-independent effects such as blood pressure-lowering and direct renal effects in diabetes. Of note, the important events in the pathogenesis of glucose-induced renal injury and DN including oxidative stress, inflammation, fibrosis and apoptosis conditions have shown to be ameliorate after the treatment with SGLT2 inhibitors. Interestingly, SGLT2 inhibitors have been reported to reduce albuminuria in DM via an activation of renal tubuloglomerular feedback by increased macula densa sodium and chloride delivery, leading to afferent vasoconstriction and attenuated diabetes-induced renal hyperfiltration. These effects also help to conserve glomerular integrity. Thus, the treatment of diabetes mellitus using SGLT2 inhibitors could be one of the effective approach for the management of diabetic-associated kidney disease like DN. This review summarizes the up to date information and discusses the bidirectional relationship between the SGLT2 inhibitor treatments and the renal functions that are available from both basic research and clinical reports. The details of renal outcomes of SGLT2 inhibitors in DN are also provide in this review.

[Role of the kidneys in glucose homeostasis. Implication of sodium-glucose cotransporter 2 (SGLT2) in diabetes mellitus treatment]

Kidney plays an important role in glucose homeostasis, both in the post-absorptive and postprandial period. Kidney produces glucose by gluconeogenesis in the renal cortex and uses glucose for covering energy needs of the medulla. Kidney participates also to the reabsorption of filtered glucose in order the terminal urine was devoided of glucose, as long as blood glucose did not exceed 180mg/dL. Reabsorption of glucose is mediated by sodium-glucose cotransporters (SGLT1 et SGLT2) expressed in S1 and S3 segments of proximal tubule. SGLT2 is the main sodium-glucose cotransporter responsible for 90% of glucose reabsorption. In type 2 diabetics, renal gluconeogenesis and glucose utilisation are increased by 30%. Surprisingly, renal glucose reabsorption is increased, participating to worsening of hyperglycemia. This results from the increase in the renal threshhold of glucose reabsorption (220mg/dL) and from an overexpression of SGLT2 in response to hyperglycemia and of cytokine secretion. The administration of SGLT2 inhibitors to type 2 diabetic patients induced a decreased in the renal threshhold of glucose reabsorption (80mg/dL) and strongly reduced kidney glucose reabsorption. The inhibitors of SGLT2 are the only antidiabetic molecules able to correct the excessive renal glucose reabsorption in type 2 diabetics and thus to contribute, by an original mechanism, to the lowering of blood glucose level.

Combined HQSAR, topomer CoMFA, homology modeling and docking studies on triazole derivatives as SGLT2 inhibitors

Aim: Sodium–glucose cotransporter 2 (SGLT2) is a promising target for diabetes therapy. We aimed to develop computational approaches to identify structural features for more potential SGLT2 inhibitors. Materials & methods: In this work, 46 triazole derivatives as SGLT2 inhibitors were studied using a combination of several approaches, including hologram quantitative structure–activity relationships (HQSAR), topomer comparative molecular field analysis (CoMFA), homology modeling, and molecular docking. HQSAR and topomer CoMFA were used to construct models. Molecular docking was conducted to investigate the interaction of triazole derivatives and homology modeling of SGLT2, as well as to validate the results of the HQSAR and topomer CoMFA models. Results: The most effective HQSAR and topomer CoMFA models exhibited noncross-validated correlation coefficients of 0.928 and 0.891 for the training set, respectively. External predictions were made successfully on a test set and then compared with previously reported models. The graphical results of HQSAR and topomer CoMFA were proven to be consistent with the binding mode of the inhibitors and SGLT2 from molecular docking. Conclusion: The models and docking provided important insights into the design of potent inhibitors for SGLT2.

Empagliflozin: a new strategy for nephroprotection in diabetes

Empagliflozin, an inhibitor of sodiumglucose symporter type 2 (SGLT2), is a new class of antidiabetic agents with numerous pleiotropic effects. The review summarises data on the influence of empagliflozin on the structural and functional changes in the kidneys of the models of diabetes mellitus (DM) and of patients with DM. A literature search was conducted using the databases of Medline/PubMed, Scopus, Web of Science, ClinicalTrials.gov and eLibrary. The experimental results showed a decrease in the blood glucose level, blood pressure, glomerular hyperfiltration and overexpression of proinflammatory and fibrogenic factors in the kidneys under the influence of empagliflozin. Most clinical studies have demonstrated the albuminuria-lowering effect of empagliflozin in patients with type 2 DM. The EMPA-REG OUTCOME study has demonstrated slowing of the chronic kidney disease progression, decrease in the incidence of end-stage renal failure and death from renal causes in patients with type 2 DM undergoing the empagliflozin treatment compared with those receiving placebo. The mechanisms of the nephroprotective effect of empagliflozin included systemic and renal effects. The decrease in hyperglycaemia, blood pressure and body weight; reduction in glomerular hyperfiltration; enhancement of sodium excretion and suppression of inflammatory and fibrogenic signalling pathways in the kidneys may help slow the development of diabetic kidney damage under the influence of empagliflozin. The possibility of extrapolating the confirmed properties of empagliflozin to other SGLT2 inhibitors needs further investigation.

Dapagliflozin modulates glucagon secretion in an SGLT2-independent manner in murine alpha cells

AIM

SGLT2 inhibitors reduce renal glucose uptake through an insulin-independent mechanism. They also increase glucagon concentration, although the extent to which this is due to a direct effect on pancreatic alpha cells remains unclear.

METHODS

In the present work, αTC1 cells treated with the SGLT2 inhibitor dapagliflozin (Dapa) were analyzed for glucose transporters, molecular mediators of hormone secretion, glucagon and GLP-1 release, and the effects of somatostatin. Data were validated in murine and human pancreatic islets.

RESULTS

SLC5A2 (the SGLT2-encoding gene) was nearly undetectable in αTC1 cells, not even by a digital PCR technique using different probes. In contrast, SLC5A1 (the SGLT1-encoding gene) was constitutively abundant in αTC1 cells and in islets, and increased with Dapa. This was associated with greater glucagon release, preceded by increased expression of preproglucagon and HNF4α. Looking at the candidate intracellular signalling pathway, reduced PASK and increased AMPK-α2 expression were also detected. GLUT1 and GLUT2, as well as regulators of glucagon release and alpha-cell phenotype (chromogranin A, paired box 6, proprotein convertase 1/2, synaptophysin), were unaffected by Dapa, as were GLP-1 receptor expression and GLP-1 release. Low glucose did not influence the stimulatory effect of Dapa on glucagon release, but was instead almost fully reverted by SLC5A1 silencing. When the effect of Dapa on AMPK and PASK, emerging regulators of lipid and glucose metabolism, was tested, upregulated AMPK-α2 appeared to be involved in molecular signalling.

CONCLUSION

Our study has shown that, in αTC1 cells, Dapa acutely upregulates SGLT1 expression and increases glucagon release through an SGLT1-dependent mechanism, with SGLT2 expression virtually undetectable. These results suggest the involvement of SGLT1 in modulating glucagon increases following SGLT2 inhibition.

SGLT2 inhibitor/DPP-4 inhibitor combination therapy - complementary mechanisms of action for management of type 2 diabetes mellitus

Type 2 diabetes mellitus is a progressive disease with multiple underlying pathophysiologic defects. Monotherapy alone cannot maintain glycemic control and leads to treatment failure. Ideally, a combination of glucose-lowering agents should have complementary mechanisms of action that address multiple pathophysiologic pathways, can be used at all stages of the disease, and be generally well tolerated with no increased risk of hypoglycemia, cardiovascular events, or weight gain. The combination should also provide conveniences for patients, such as oral dosing, single-pill formulations, and once-daily administration, potentially translating to improved adherence. Two classes of glucose-lowering agents that meet these criteria are the sodium glucose cotransporter-2 (SGLT2) inhibitors and dipeptidyl peptidase-4 (DPP-4) inhibitors. This article reviews the rationale for combination therapy with these agents, and evidence from clinical trials with empagliflozin and linagliptin or dapagliflozin and saxagliptin in the management of type 2 diabetes mellitus. Both combinations have been approved as single-pill formulations.

Active Brown Fat During 18F-FDG PET/CT Imaging Defines a Patient Group with Characteristic Traits and an Increased Probability of Brown Fat Redetection

Brown adipose tissue (BAT) provides a means of nonshivering thermogenesis. In humans, active BAT can be visualized by ¹⁸F-FDG uptake as detected by PET combined with CT. The retrospective analysis of clinical scans is a valuable source to identify anthropometric parameters that influence BAT mass and activity and thus the potential efficacy of envisioned drugs targeting this tissue to treat metabolic disease. Methods: We analyzed 2,854 ¹⁸F-FDG PET/CT scans from 1,644 patients and identified 98 scans from 81 patients with active BAT. We quantified the volume of active BAT depots (mean values in mL ± SD: total BAT, 162 ± 183 [n = 98]; cervical, 40 ± 37 [n = 53]; supraclavicular, 66 ± 68 [n = 71]; paravertebral, 51 ± 53 [n = 69]; mediastinal, 43 ± 40 [n = 51]; subphrenic, 21 ± 21 [n = 29]). Because only active BAT is detectable by ¹⁸F-FDG uptake, these numbers underestimate the total amount of BAT. Considering only 32 scans of the highest activity as categorized by a visual scoring strategy, we determined a mean total BAT volume of 308 ± 208 mL. In 30 BAT-positive patients with 3 or more repeated scans, we calculated a much higher mean probability to redetect active BAT (52% ± 25%) as compared with the overall prevalence of 4.9%. We calculated a BAT activity index (BFI) based on volume and intensity of individual BAT depots. Results: We detected higher total BFI in younger patients (P = 0.009), whereas sex, body mass index, height, mass, outdoor temperature, and blood parameters did not affect total or depot-specific BAT activity. Surprisingly, renal creatinine clearance as estimated from mass, age, and plasma creatinine was a significant predictor of BFI on the total (P = 0.005) as well as on the level of several individual depots. In summary, we detected a high amount of more than 300 mL of BAT tissue. Conclusion: BAT-positive patients represent a group with a higher than usual probability to activate BAT during a scan. Estimated renal creatinine clearance correlated with the extent of activated BAT in a given scan. These data imply an efficacy of drugs targeting BAT to treat metabolic disease that is at the same time higher and subject to a larger individual variation than previously assumed.

Novel SGLT2 inhibitor: first-in-man studies of antisense compound is associated with unexpected renal effects

The antisense compound ISIS 388626 selectively inhibits renal glucose reabsorption by inhibiting the sodium–glucose cotransporter‐2 (SGLT2) mRNA expression. It is developed as an insulin‐independent treatment approach for type 2 diabetes mellitus (T2DM). The safety, tolerability, pharmacokinetics, and pharmacodynamics after subcutaneous administration of the drug were planned to be evaluated in healthy volunteers in a single‐ascending‐dose study (50–400 mg) and a multiple‐ascending‐dose study (6 weeks; weekly doses of 50–400 mg with loading dose regimen of three doses during the first week). The study was halted early because increases in serum creatinine occurred in the subjects participating in the 100 mg multiple‐dose cohort. The pronounced changes in serum creatinine were accompanied by increased urinary excretion of beta‐2‐microglobulin and KIM1. The possible mechanisms for these findings remain elusive and are in contrast to preclinical findings as comparable treatment with ISIS 388626 of animals did not reveal similar changes. Although exposure was limited, there was an indication that glucosuria increased upon active treatment. Before the concept of antisense‐mediated blocking of SGLT2 with ISIS 388626 can be explored further, more preclinical data are needed to justify further investigations.

Role of SGLT2 inhibitors in the treatment of type 2 diabetes mellitus

In the last ten years, knowledge on pathophysiology of type 2 diabetes (T2DM) has significantly increased, with multiple failures (decreased incretin effect, increased lipolysis, increased glucagon secretion, neurotransmitters dysfunction) recognized as important contributors, together with decreased insulin secretion and reduced peripheral glucose uptake. As a consequence, the pharmacologic therapy of T2DM has been progressively enriched by several novel classes of drugs, trying to overcome these defects. The last, intriguing compounds come into the market are SGLT2 inhibitors, framing the kidney in a different scenario, not as site of a harmful disease complication, but rather as the means to correct hyperglycemia and fight the disease. This review aims to offer a short, updated overview of the role of these compounds in the treatment of T2DM, focusing on efficacy, ancillary albeit relevant clinical effects, safety, potential cardiovascular protection, positioning in common therapeutic algorithms.

Sodium Glucose Cotransporter 2 Inhibitors in the Treatment of Diabetes Mellitus: Cardiovascular and Kidney Effects, Potential Mechanisms, and Clinical Applications

Sodium-glucose cotransporter-2 (SGLT2) inhibitors, including empagliflozin, dapagliflozin, and canagliflozin, are now widely approved antihyperglycemic therapies. Because of their unique glycosuric mechanism, SGLT2 inhibitors also reduce weight. Perhaps more important are the osmotic diuretic and natriuretic effects contributing to plasma volume contraction, and decreases in systolic and diastolic blood pressures by 4 to 6 and 1 to 2 mm Hg, respectively, which may underlie cardiovascular and kidney benefits. SGLT2 inhibition also is associated with an acute, dose-dependent reduction in estimated glomerular filtration rate by ≈5 mL·min(-1)·1.73 m(-2) and ≈30% to 40% reduction in albuminuria. These effects mirror preclinical observations suggesting that proximal tubular natriuresis activates renal tubuloglomerular feedback through increased macula densa sodium and chloride delivery, leading to afferent vasoconstriction. On the basis of reduced glomerular filtration, glycosuric and weight loss effects are attenuated in patients with chronic kidney disease (estimated glomerular filtration rate <60 mL·min(-1)·1.73 m(-2)). In contrast, blood pressure lowering, estimated glomerular filtration rate, and albuminuric effects are preserved, and perhaps exaggerated in chronic kidney disease. With regard to long-term clinical outcomes, the EMPA-REG OUTCOME trial (Empagliflozin, Cardiovascular Outcomes, and Mortality in Type 2 Diabetes) in patients with type 2 diabetes mellitus and established cardiovascular disease randomly assigned to empagliflozin versus placebo reported a 14% reduction in the primary composite outcome of cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, and >30% reductions in cardiovascular mortality, overall mortality, and heart failure hospitalizations associated with empagliflozin, even though, by design, the hemoglobin A1c difference between the randomized groups was marginal. Aside from an increased risk of mycotic genital infections, empagliflozin-treated patients had fewer serious adverse events, including a lower risk of acute kidney injury. In light of the EMPA-REG OUTCOME results, some diabetes clinical practice guidelines now recommend that SGLT2 inhibitors with proven cardiovascular benefit be prioritized in patients with type 2 diabetes mellitus who have not achieved glycemic targets and who have prevalent atherosclerotic cardiovascular disease. With additional cardiorenal protection trials underway, sodium-related physiological effects of SGLT2 inhibitors and clinical correlates of natriuresis, such as the impact on blood pressure, heart failure, kidney protection, and mortality, will be a major management focus.

Mobilization and removing of cadmium from kidney by GMDTC utilizing renal glucose reabsorption pathway

Chronic exposure to cadmium compounds (Cd(2+)) is one of the major public health problems facing humans in the 21st century. Cd(2+) in the human body accumulates primarily in the kidneys which leads to renal dysfunction and other adverse health effects. Efforts to find a safe and effective drug for removing Cd(2+) from the kidneys have largely failed. We developed and synthesized a new chemical, sodium (S)-2-(dithiocarboxylato((2S,3R,4R,5R)-2,3,4,5,6 pentahydroxyhexyl)amino)-4-(methylthio) butanoate (GMDTC). Here we report that GMDTC has a very low toxicity with an acute lethal dose (LD50) of more than 10,000mg/kg or 5000mg/kg body weight, respectively, via oral or intraperitoneal injection in mice and rats. In in vivo settings, up to 94% of Cd(2+) deposited in the kidneys of Cd(2+)-laden rabbits was removed and excreted via urine following a safe dose of GMDTC treatment for four weeks, and renal Cd(2+) level was reduced from 12.9μg/g to 1.3μg/g kidney weight. We observed similar results in the mouse and rat studies. Further, we demonstrated both in in vitro and in animal studies that the mechanism of transporting GMDTC and GMDTC-Cd complex into and out of renal tubular cells is likely assisted by two glucose transporters, sodium glucose cotransporter 2 (SGLT2) and glucose transporter 2 (GLUT2). Collectively, our study reports that GMDTC is safe and highly efficient in removing deposited Cd(2+) from kidneys assisted by renal glucose reabsorption system, suggesting that GMDTC may be the long-pursued agent used for preventive and therapeutic purposes for both acute and chronic Cd(2+) exposure.

Sodium-glucose cotransporter 2 inhibition: cardioprotection by treating diabetes-a translational viewpoint explaining its potential salutary effects

Diabetes is a growing epidemic worldwide characterized by an elevated concentration of blood glucose, associated with a high incidence of cardiovascular disease and mortality. Although in general reduction of hyperglycaemia is considered a therapeutic goal, hypoglycaemic therapies do not necessarily reduce cardiovascular mortality and may even aggravate cardiovascular risk factors, such as body weight. A new class of antidiabetic drugs acts by inhibition of the sodium-glucose cotransporter 2 (SGLT2), which (partially) prevents reabsorption of glucose from the renal filtrate. The induction of glucose excretion via the urine (glycosuria) was turned into an effective strategy to reduce blood glucose. Ancillary advantages are the caloric and volumetric loss and thereby the reduction of body weight and blood pressure. Additionally, SGLT2 inhibition has been suggested to exert direct cardioprotective effects by the reduction of cardiac fibrosis, inflammation, and oxidative stress. This article summarizes the functional consequences of SGLT2 inhibition on the diabetic and hyperglycaemic organism. We especially focused on the effects on the kidney and the cardiovascular system as described in experimental studies. The interesting observations in experimental studies may extend to clinical medicine, as a recent trial reported a decrease in heart failure outcomes in patients at high cardiovascular risk. In conclusion, SGLT2 inhibition represents a novel treatment, which might be a promising target not only to (further) reduce blood glucose but also to target other cardiovascular risk factors. More research and long-term follow-ups will reveal the specific influence of SGLT2 inhibition on the circulatory system and cardiovascular outcomes.

Characterization and comparison of sodium-glucose cotransporter 2 inhibitors in pharmacokinetics, pharmacodynamics, and pharmacologic effects

The sodium-glucose cotransporter (SGLT) 2 offer a novel approach to treating type 2 diabetes by reducing hyperglycaemia via increased urinary glucose excretion. In the present study, the pharmacokinetic, pharmacodynamic, and pharmacologic properties of all six SGLT2 inhibitors commercially available in Japan were investigated and compared. Based on findings in normal and diabetic mice, the six drugs were classified into two categories, long-acting: ipragliflozin and dapagliflozin, and intermediate-acting: tofogliflozin, canagliflozin, empagliflozin, and luseogliflozin. Long-acting SGLT2 inhibitors exerted an antihyperglycemic effect with lower variability of blood glucose level via a long-lasting increase in urinary glucose excretion. In addition, ipragliflozin and luseogliflozin exhibited superiority over the others with respect to fast onset of pharmacological effect. Duration and onset of the pharmacologic effects seemed to be closely correlated with the pharmacokinetic properties of each SGLT2 inhibitor, particularly with respect to high distribution and long retention in the target organ, the kidney. While all six SGLT2 inhibitors were significantly effective in increasing urinary glucose excretion and reducing hyperglycemia, our findings suggest that variation in the quality of daily blood glucose control associated with duration and onset of pharmacologic effects of each SGLT2 inhibitor might cause slight differences in rates of improvement in type 2 diabetes.