Role of sodium-glucose cotransporter 2 (SGLT 2) inhibitors in the treatment of type 2 diabetes

Dapagliflozin Binds Specifically to Sodium-Glucose Cotransporter 2 in the Proximal Renal Tubule

Kidneys contribute to glucose homeostasis by reabsorbing filtered glucose in the proximal tubules via sodium-glucose cotransporters (SGLTs). Reabsorption is primarily handled by SGLT2, and SGLT2-specific inhibitors, including dapagliflozin, canagliflozin, and empagliflozin, increase glucose excretion and lower blood glucose levels. To resolve unanswered questions about these inhibitors, we developed a novel approach to map the distribution of functional SGLT2 proteins in rodents using positron emission tomography with 4-[¹⁸F]fluoro-dapagliflozin (F-Dapa). We detected prominent binding of intravenously injected F-Dapa in the kidney cortexes of rats and wild-type and Sglt1-knockout mice but not Sglt2-knockout mice, and injection of SGLT2 inhibitors prevented this binding. Furthermore, imaging revealed only low levels of F-Dapa in the urinary bladder, even after displacement of kidney binding with dapagliflozin. Microscopic ex vitro autoradiography of kidney showed F-Dapa binding to the apical surface of early proximal tubules. Notably, in vivo imaging did not show measureable specific binding of F-Dapa in heart, muscle, salivary glands, liver, or brain. We propose that F-Dapa is freely filtered by the kidney, binds to SGLT2 in the apical membranes of the early proximal tubule, and is subsequently reabsorbed into blood. The high density of functional SGLT2 transporters detected in the apical membrane of the proximal tubule but not detected in other organs likely accounts for the high kidney specificity of SGLT2 inhibitors. Overall, these data are consistent with data from clinical studies on SGLT2 inhibitors and provide a rationale for the mode of action of these drugs.

New perspectives on research of sodium-glucose cotransporters 1 and 2

Sodium-glucose cotransporters (SGLTs) are a family of glucose transporters located in the mucosa of the small intestine and the proximal tubule of the nephron. They are important mediators of glucose uptake across cell membranes. According to recent basic studies and clinical trials, SGLT2 controls renal glucose reabsorption and its inhibitors not only act as antihyperglycemia agents via increment of urinary glucose excretion but also decrease blood pressure to exert a cardioprotective effect. When SGLT2 is inhibited, SGLT1 compensates for the function of SGLT2 in renal glucose reabsorption, weakening the hypoglycemic action of SGLT2 inhibitors. In the small intestine, SGLT1 also mediates almost the whole sodium-dependent glucose uptake. As a result, SGLT1 inhibitors have therapeutic potential for diabetes. In addition, the expression of SGLT1 is associated with gastrointestinal hormones such as glucagon-like peptide 1 (GLP-1) and taste receptors. Therefore, it can have an impact on human feeding behaviors and appetite and be involved in the pathogenesis of obesity. This review focuses on the physiological functions of SGLT1 and SGLT2, their interaction with taste receptors and intestinal hormone, and their prospects as new therapeutic targets for diabetes management.

The effects of canagliflozin, a sodium glucose co-transporter 2 inhibitor, on mineral metabolism and bone in patients with type 2 diabetes mellitus

BACKGROUND

Sodium glucose co-transporter 2 (SGLT2) inhibitors lower blood glucose levels in patients with type 2 diabetes mellitus (T2DM) by increasing urinary glucose excretion. This review provides a comprehensive summary of preclinical and clinical data on the effects of the SGLT2 inhibitor canagliflozin on mineral balance and bone.

METHODS

Published articles and internal study reports through November 2015 were included.

RESULTS

In clinical studies, canagliflozin was not associated with meaningful changes in serum or urine calcium, parathyroid hormone, or vitamin D. Canagliflozin was associated with increases in serum magnesium and phosphate without changes in their urinary excretion. Increases in serum collagen type-1 beta-carboxy-telopeptide (beta-CTX), a bone resorption marker, and osteocalcin, a bone formation marker, were observed with canagliflozin. Decreases in total hip bone mineral density (BMD) of up to 1.2% were seen with canagliflozin after 2 years; no changes in BMD were seen at other skeletal sites. Changes in total hip BMD and serum beta-CTX with canagliflozin correlated with decreases in body weight. In a clinical program-wide analysis, canagliflozin was associated with increased fracture risk that was driven by a higher incidence in the cardiovascular safety study (CANVAS), with no fracture imbalance seen in pooled data from other Phase 3 studies. The fracture imbalance occurred within 12 weeks after initiating treatment, most frequently in the distal portion of the upper and lower extremities.

CONCLUSIONS

Across clinical studies, canagliflozin did not meaningfully affect calcium homeostasis or hormones regulating calcium homeostasis. Increases in bone turnover markers and decreases in BMD at the total hip, but not at other sites, that correlated with weight loss were seen with canagliflozin. Canagliflozin was associated with a higher fracture incidence within 12 weeks, primarily in distal extremities. Data from ongoing canagliflozin studies will provide additional information on fracture risk.

Positioning SGLT2 Inhibitors/Incretin-Based Therapies in the Treatment Algorithm

Sodium-glucose cotransporter 2 inhibitors (SGLT2i) are the most recent addition to the therapeutic options available for the treatment of type 2 diabetes and became available after the introduction of incretin-based therapies, dipeptidyl peptidase 4 inhibitors and glucagon-like peptide 1 receptor agonists (GLP-1 RAs). These agents have potential advantages with regard to their weight loss-promoting effect, low risk of hypoglycemia, reduction in blood pressure, and reduction in cardiovascular events in high-risk patients (with empagliflozin). Apart from these clinically important outcomes, they may also correct core defects present in type 2 diabetes (i.e., improvement in β-cell function and insulin sensitivity). They do, however, have some adverse effects, notably, nausea with GLP-1 RAs and genital tract infections and potential for volume depletion with SGLT2i. Whether incretin-based therapies are associated with an increased risk of pancreatitis is unclear. Most recently, diabetic ketoacidosis has been reported with SGLT2i. Therefore, a key clinical question in relation to guidelines is whether these clinical advantages, in the context of the adverse effect profile, outweigh the additional cost compared with older, more established therapies. This article reviews the therapeutic rationale for the use of these newer drugs for diabetes treatment, considers their place in current guidelines, and discusses how this may change as new data emerge about their long-term efficacy and safety from ongoing outcome trials.

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.

Sodium-Glucose Cotransporter 2 Inhibitor and a Low Carbohydrate Diet Affect Gluconeogenesis and Glycogen Content Differently in the Kidney and the Liver of Non-Diabetic Mice

A low carbohydrate diet (LCHD) as well as sodium glucose cotransporter 2 inhibitors (SGLT2i) may reduce glucose utilization and improve metabolic disorders. However, it is not clear how different or similar the effects of LCHD and SGLT2i are on metabolic parameters such as insulin sensitivity, fat accumulation, and especially gluconeogenesis in the kidney and the liver. We conducted an 8-week study using non-diabetic mice, which were fed ad-libitum with LCHD or a normal carbohydrate diet (NCHD) and treated with/without the SGLT-2 inhibitor, ipragliflozin. We compared metabolic parameters, gene expression for transcripts related to glucose and fat metabolism, and glycogen content in the kidney and the liver among the groups. SGLT2i but not LCHD improved glucose excursion after an oral glucose load compared to NCHD, although all groups presented comparable non-fasted glycemia. Both the LCHD and SGLT2i treatments increased calorie-intake, whereas only the LCHD increased body weight compared to the NCHD, epididimal fat mass and developed insulin resistance. Gene expression of certain gluconeogenic enzymes was simultaneously upregulated in the kidney of SGLT2i treated group, as well as in the liver of the LCHD treated group. The SGLT2i treated groups showed markedly lower glycogen content in the liver, but induced glycogen accumulation in the kidney. We conclude that LCHD induces deleterious metabolic changes in the non-diabetic mice. Our results suggest that SGLT2i induced gluconeogenesis mainly in the kidney, whereas for LCHD it was predominantly in the liver.

Apoptosis in pancreatic β-islet cells in Type 2 diabetes

Apoptosis plays important roles in the pathophysiology of Type 2 diabetes mellitus (T2DM). The etiology of T2DM is multifactorial, including obesity-associated insulin resistance, defective insulin secretion, and loss of β-cell mass through β-cell apoptosis. β-cell apoptosis is mediated through a milliard of caspase family cascade machinery in T2DM. The glucose-induced insulin secretion is the principle pathophysiology of diabetes and insufficient insulin secretion results in chronic hyperglycemia, diabetes. Recently, hyperglycemia-induced β-cell apoptosis has been extensively studied on the balance of pro-apoptotic Bcl-2 proteins (Bad, Bid, Bik, and Bax) and anti-apoptotic Bcl family (Bcl-2 and Bcl-xL) toward apoptosis in vitro isolated islets and insulinoma cell culture. Apoptosis can only occur when the concentration of pro-apoptotic Bcl-2 exceeds that of anti-apoptotic proteins at the mitochondrial membrane of the intrinsic pathway. A bulk of recent research on hyperglycemia-induced apoptosis on β-cells unveiled complex details on glucose toxicity on β-cells in molecular levels coupled with cell membrane potential by adenosine triphosphate generation through K+ channel closure, opening Ca2+ channel and plasma membrane depolarization. Furthermore, animal models using knockout mice will shed light on the basic understanding of the pathophysiology of diabetes as a glucose metabolic disease complex, on the balance of anti-apoptotic Bcl family and pro-apoptotic genes. The cumulative knowledge will provide a better understanding of glucose metabolism at a molecular level and will lead to eventual prevention and therapeutic application for T2DM with improving medications.

EMPA-REG and Other Cardiovascular Outcome Trials of Glucose-lowering Agents: Implications for Future Treatment Strategies in Type 2 Diabetes Mellitus

During the last decade, the armamentarium for glucose-lowering drugs has increased enormously by the development of DPP-4 inhibitors, GLP-1 receptor agonists and SGLT2 inhibitors, allowing individualization of antidiabetic therapy for patients with type 2 diabetes (T2DM). Some combinations can now be used without an increased risk for severe hypoglycemia and weight gain. Following a request of the US Food and Drug Administration, many large cardiovascular (CV) outcome studies have been performed in patients with longstanding disease and established CV disease. In the majority of CV outcome studies, CV risk factors were well controlled and a high number of patients were already treated with ACE inhibitors/angiotensin receptor blockers, statins and antiplatelet drugs. Most studies with insulin glargine and newer glucose-lowering drugs (saxagliptin, alogliptin, sitagliptin, lixisenatide) demonstrated safety of newer glucose-lowering agents but did not show superiority in the CV outcomes compared with placebo. By contrast, in the EMPA-REG OUTCOME (Empagliflozin Cardiovascular Outcome Event Trial in Type 2 Diabetes Mellitus Patients) study, CV death, all-cause mortality, and hospitalization for heart failure were significantly decreased when empagliflozin was added instead of placebo to therapy for patients with high CV risk and T2DM already well treated with statins, glucose-lowering drugs, and blood pressure-lowering drugs as well as antiplatelet agents. In addition, renal endpoints including endstage renal disease were also significantly reduced when empagliflozin was added instead of placebo. Interestingly, the reduction of these clinically relevant end points was observed after a few months, making antiatherogenic effects an unlikely cause. The fact that the incidence of myocardial infarction (MI) and stroke were not reduced is in line with the hypothesis that hemodynamic factors in particular have contributed to the impressive improvement of the prognosis. To reduce the CV burden of patients with T2DM, drugs influencing factors involved in atherogenesis (eg, insulin resistance, chronic inflammation, increase of HDL, prothrombotic state) are more promising. The recent IRIS (Insulin Resistance Intervention after Stroke) study documented a significant reduction in stroke and MI when pioglitazone instead of placebo was given to nondiabetic patients presenting with both stroke/transient ischemic attack and insulin resistance, confirming results from the PROactive (Prospective Pioglitazone Clinical Trial in Macrovascular Events) study in patients with T2DM. Based on these new data, we suggest that the addition of both empagliflozin and pioglitazone to metformin might be the relative best option to reduce the high CV morbidity and mortality of patients with T2DM and already established CV complications. The very recent announcement that the CV outcome study with liraglutide (LEADER) also demonstrated a significant reduction of the composite endpoint (cardiovascular death, non-fatal myocardial infarction or non-fatal stroke) gives new hope for further beneficial treatment options for T2DM patients with established CVD.

Revitalization of pioglitazone: the optimum agent to be combined with a sodium-glucose co-transporter-2 inhibitor

The recently completed EMPA-REG study showed that empagliflozin significantly decreased the major adverse cardiac events (MACE) endpoint, which comprised cardiovascular death, non-fatal myocardial infarction (MI) and stroke, in patients with high-risk type 2 diabetes (T2DM), primarily through a reduction in cardiovascular death, without a significant decrease in either MI or stroke. In the PROactive study, pioglitazone decreased the MACE endpoint by a similar degree to that observed in the EMPA-REG study, through a marked reduction in both recurrent MI and stroke and a modest reduction in cardiovascular death. These observations suggest that pioglitazone might be an ideal agent to combine with empagliflozin to further reduce cardiovascular events in patients with high-risk diabetes as empagliflozin also promotes salt/water loss and would be expected to offset any fluid retention associated with pioglitazone therapy. In the present paper, we provide an overview of the potential benefits of combined pioglitazone/empagliflozin therapy to prevent cardiovascular events in patients with T2DM.

Glucose-lowering therapy in type 2 diabetes. New hope after the EMPA-REG outcome trial

Prevention of cardiovascular morbidity and mortality remains the key factor in the treatment of type 2 diabetes (T2DM). In the early phase of T2DM, multifactorial intervention is mandatory and glucose levels should be near normal, in particular in younger patients presenting with the highest cardiovascular risk. Anti-diabetic drugs without any risk for hypoglycaemia should be preferred in order to reduce clinical inertia and increase the long-term adherence to the treatment. In patients already presenting with cardiovascular disease, the best outcome may be expected with the triple oral therapy of metformin, pioglitazone, and empagliflozin, although a controlled prospective study versus insulin therapy is needed to confirm the expectation.

SGLT2 Inhibitors and Cardiovascular Risk: Lessons Learned From the EMPA-REG OUTCOME Study

Although cardiovascular (CV) mortality is the principal cause of death in individuals with type 2 diabetes (T2DM), reduction of plasma glucose concentration has little effect on CV disease (CVD) risk. Thus, novel strategies to reduce CVD risk in T2DM patients are needed. The recently published BI 10773 (Empagliflozin) Cardiovascular Outcome Event Trial in Type 2 Diabetes Mellitus Patients (EMPA-REG OUTCOME) study demonstrated that in T2DM patients with high CVD risk empagliflozin reduced the primary major adverse cardiac event end point (CV death, nonfatal myocardial infarction, nonfatal stroke) by 14%. This beneficial effect was driven by a 38% reduction in CV mortality with no significant decrease in nonfatal myocardial infarction or stroke. Empagliflozin also caused a 35% reduction in hospitalization for heart failure without affecting hospitalization for unstable angina. Although sodium-glucose cotransporter 2 inhibitors exert multiple metabolic benefits (decreases in HbA1c, body weight, and blood pressure and an increase in HDL cholesterol), all of which could reduce CVD risk, it is unlikely that the reduction in CV mortality can be explained by empagliflozin's metabolic effects. More likely, hemodynamic effects, specifically reduced blood pressure and decreased extracellular volume, are responsible for the reduction in CV mortality and heart failure hospitalization. In this Perspective, we will discuss possible mechanisms for these beneficial effects of empagliflozin and their implications for the care of T2DM patients.

Sodium-glucose co-transporter-2 inhibitors and dipeptidyl peptidase-4 inhibitors combination therapy in type 2 diabetes: A systematic review of current evidence

As type 2 diabetes mellitus (T2DM) is a chronic and progressive disease with multiple pathophysiologic defects, no single anti-diabetic agent can tackle all these multi-factorial pathways. Consequently, multiple agents working through the different mechanisms will be required for the optimal glycemic control. Moreover, the combination therapies of different anti-diabetic agents may complement their actions and possibly act synergistic. Furthermore, these combinations could possess the additional properties to counter their undesired physiological compensatory response. Sodium-glucose co-transporter-2 inhibitors (SGLT-2I) are newly emerging class of drugs, with a great potential to reduce glucose effectively with an additional quality of lowering cardiovascular events as demonstrated very recently by one of the agents of this class. However, increase in endogenous glucose production (EGP) from the liver, either due to the increase in glucagon or compensatory response to glucosuria can offset the glucose-lowering potential of SGLT-2I. Interestingly, another class of drugs such as dipeptidyl peptidase-4 inhibitors (DPP-4I) effectively decrease glucagon and reduce EGP. In light of these findings, combination therapies with SGLT-2I and DPP-4I are particularly appealing and are expected to produce a synergistic effect. Preclinical studies of combination therapies with DPP-4I and SGLT-2I have already demonstrated a significant lowering of hemoglobin A1c potential and human studies also find no drug-drug interaction between these agents. This article aims to systematically review the efficacy and safety of combination therapy of SGLT-2I and DPP-4I in T2DM.

Effect of Dapagliflozin With and Without Acipimox on Insulin Sensitivity and Insulin Secretion in T2DM Males

AIM

To investigate the effect of lowering the plasma glucose and free fatty acid (FFA) concentrations with dapagliflozin and acipimox, respectively, on insulin sensitivity and insulin secretion in T2DM individuals.

METHODS

Fourteen male T2DM patients received an oral glucose tolerance test and euglycemic hyperinsulinemic clamp at baseline and were treated for 3 weeks with dapagliflozin (10 mg per day). During week 3, acipimox (250 mg four times per day) treatment was added to dapagliflozin. The oral glucose tolerance test and insulin clamp were repeated at the end of weeks 2 and 3.

RESULTS

Dapagliflozin caused glucosuria and significantly lowered the plasma glucose concentration (by 35 mg/dL; P < .01), whereas the fasting plasma FFA concentration was unaffected. Acipimox caused a further decrease in the fasting plasma glucose concentration (by 20 mg/dL; P < .01) and a significant decrease in the fasting plasma FFA concentration. Compared to baseline, insulin-mediated glucose disposal increased significantly at week 2 (from 4.48 ± 0.50 to 5.30 ± 0.50 mg/kg · min; P < .05). However, insulin-mediated glucose disposal at week 3 (after the addition of acipimox) did not differ significantly from that at week 2. Glucose-stimulated insulin secretion at week 2 increased significantly compared to baseline, and it increased further and significantly at week 3 compared to week 2.

CONCLUSION

Lowering the plasma glucose concentration with dapagliflozin improves both insulin sensitivity and β-cell function, whereas lowering plasma FFA concentration by addition of acipimox to dapagliflozin improves β-cell function without significantly affecting insulin sensitivity.

Pharmacokinetics, Pharmacodynamics and Clinical Use of SGLT2 Inhibitors in Patients with Type 2 Diabetes Mellitus and Chronic Kidney Disease

Inhibitors of sodium-glucose cotransporters type 2 (SGLT2) are proposed as a novel approach for the management of type 2 diabetes mellitus. SGLT2 cotransporters are responsible for reabsorption of 90 % of the glucose filtered by the kidney. The glucuretic effect resulting from SGLT2 inhibition contributes to reduce hyperglycaemia and also assists weight loss and blood pressure reduction. Several SGLT2 inhibitors are already available in many countries (dapagliflozin, canagliflozin, empagliflozin) and in Japan (ipragliflozin, tofogliflozin). These SGLT2 inhibitors share similar pharmacokinetic characteristics with a rapid oral absorption, a long elimination half-life allowing once-daily administration, an extensive hepatic metabolism mainly via glucuronidation to inactive metabolites and a low renal elimination as a parent drug. Pharmacokinetic parameters are slightly altered in the case of chronic kidney disease (CKD). While no dose adjustment is required in the case of mild CKD, SGLT2 inhibitors may not be used or only at a lower daily dose in patients with moderate CKD. Furthermore, the pharmacodynamic response to SGLT2 inhibitors as assessed by urinary glucose excretion declines with increasing severity of renal impairment as assessed by a reduction in the estimated glomerular filtration rate. Nevertheless, the glucose-lowering efficacy and safety of SGLT2 inhibitors are almost comparable in patients with mild CKD as in patients with normal kidney function. In patients with moderate CKD, the efficacy tends to be dampened and safety concerns may occur. In patients with severe CKD, the use of SGLT2 inhibitors is contraindicated. Thus, prescribing information should be consulted regarding dosage adjustments or restrictions in the case of renal dysfunction for each SGLT2 inhibitor. The clinical impact of SGLT2 inhibitors on renal function and their potential to influence the course of diabetic nephropathy deserve attention because of preliminary favourable results in animal models.

A Safety Evaluation of Empagliflozin for the Treatment of Type 2 Diabetes

INTRODUCTION

Empagliflozin is a sodium glucose co-transporter 2 inhibitor used to improve glycemic control in adults with type 2 diabetes mellitus (T2DM) by enhancing urinary glucose excretion. Empagliflozin is effective at lowering glycosylated hemoglobin and was recently proven superior to placebo for reduction of cardiovascular disease (CVD) risk. As with any new drug, there are safety considerations that inform its potential use in patients with T2DM.

AREAS COVERED

Here, we evaluate the safety of empagliflozin and provide an expert opinion as to its current and future role in the treatment of patients with T2DM. A search of the English language literature was performed using PubMed search terms: "empagliflozin", "sodium glucose cotransporter 2 inhibitors", and "drug safety". Articles and bibliographies relevant to the subject were reviewed and additional references known to the authors were included.

EXPERT OPINION

The evidence for empagliflozin is robust with regard to glycemic efficacy and safety. Low risk of hypoglycemia, absence of weight gain, and demonstrated cardiovascular risk reduction support its consideration as a first line medication in addition to metformin for patients with T2DM and CVD. Ongoing trials will continue to address the safety and efficacy of empagliflozin and expand our clinical knowledge of this medication.

The SGLT2 inhibitor empagliflozin improves insulin sensitivity in db/db mice both as monotherapy and in combination with linagliptin

AIMS

Combining different drug classes to improve glycemic control is one treatment strategy for type 2 diabetes. The effects on insulin sensitivity of long-term treatment with the sodium glucose co-transporter 2 (SGLT2) inhibitor empagliflozin alone or co-administered with the dipeptidyl peptidase-4 inhibitor linagliptin (both approved antidiabetes drugs) were investigated in mice using euglycemic-hyperinsulinemic clamps.

MATERIALS AND METHODS

db/db mice (n=15/group) were treated for 8weeks with 10mg/kg/day empagliflozin monotherapy, 10mg/kg/day empagliflozin plus 3mg/kg/day linagliptin combination therapy, or 3mg/kg/day linagliptin monotherapy. At the end of the study, euglycemic-hyperinsulinemic clamp studies were performed 4days after the last dose of treatment.

RESULTS

HbA1c and 2-hour fasting glucose concentrations were improved with empagliflozin monotherapy and combination therapy compared with vehicle and linagliptin monotherapy. During the clamp, glucose disposal rates increased and hepatic glucose production decreased with empagliflozin monotherapy and combination therapy compared with vehicle and linagliptin monotherapy. Glucose uptake in liver and kidney was higher with empagliflozin monotherapy and combination therapy compared with vehicle; glucose uptake into both muscle and adipose tissue was only affected by linagliptin treatment. Empagliflozin and combination therapy altered the expression of genes involved in the inflammatory response, fatty acid synthesis and oxidation.

CONCLUSIONS

These findings suggest that the insulin-sensitizing effects of SGLT2 inhibition contribute to improvements in glycemic control in insulin-resistant states.

Impact of the 8-week Administration of Tofogliflozin for Glycemic Control and Body Composition in Japanese Patients with Type 2 Diabetes Mellitus

Objective The adverse effects of selective sodium-glucose co-transporter 2 (SGLT2) inhibitors generally appear within about two or three months after treatment initiation in Japan. Therefore, we investigated the impact of tofogliflozin, a class of SGLT2 inhibitors, on glycemic control and body composition during this period in Japanese patients with type 2 diabetes mellitus. Methods This single-arm open-label study enrolled 20 patients. Patients received tofogliflozin 20 mg once daily for 8 weeks. At week 8, changes from baseline in body weight, serum metabolic markers, and body composition were evaluated. Results A total of 17 patients completed the 8-week administration of tofogliflodin. No serious adverse events were noted. Hemoglobin A1c (HbA1c) decreased significantly, from 7.8% to 7.3% with 8-week administration of tofogliflozin. Both the body weight and body mass index (BMI) also decreased. In addition, a decreased renal function of the boundary zone and hemoconcentration were detected. As for body composition, the free fat mass, total body water, extracellular water and intracellular water were all decreased significantly. Interestingly, the amount of fat mass did not change. The degree of improvement in HbA1c was correlated with the baseline fat mass and BMI. Conclusion An eight-week administration of tofogliflozin improved glycemic control and reduced the body weight and free fat mass in type 2 diabetic patients without affecting the fat mass. In this period, the hematocrit level and renal function should be monitored to guard against hemoconcentration and renal impairment, respectively.

Circulating SerpinB1 levels and clinical features in patients with type 2 diabetes

OBJECTIVE

The main purpose of this study was to investigate the association of serum SerpinB1 levels and various parameters in patients with type 2 diabetes. The effect of canagliflozin (a sodium glucose cotransporter 2 (SGLT2) inhibitor), which can decrease circulating insulin levels, on serum SerpinB1 levels was also investigated. A recent study suggests that the serum levels of SerpinB1, also known as monocyte neutrophil elastase inhibitor, increase with insulin resistance, may have a protective effect for pancreatic β cells, and may decrease insulin resistance.

RESEARCH DESIGN AND METHODS

The study included 30 patients with type 2 diabetes hospitalized for glycemic control and 10 control subjects.

RESULTS

SerpinB1 levels were significantly higher in patients with type 2 diabetes, compared with that in heathy control subjects (10.01±3.59 vs 5.69±1.64 ng/mL, p<0.0001). Serum SerpinB1 levels had a significant negative correlation with low-density lipoprotein cholesterol (LDL-C) (p=0.0123). Serum SerpinB1 levels had a significant positive association or trend toward a positive association with age and with hemoglobin A1c (HbA1c), and significant negative association with LDL-C levels in some multiple regression analysis models. Patients treated with statins had a tendency toward higher serum SerpinB1 levels, compared with those patients not treated with statins. During a 3-day observation period both with and without canagliflozin treatment, the serum SerpinB1 levels did not change.

CONCLUSIONS

Serum SerpinB1 levels are elevated in patients with type 2 diabetes compared with that in healthy subjects and are negatively correlated with serum LDL-C.

Combination therapy of sodium-glucose co-transporter-2 inhibitors and dipeptidyl peptidase-4 inhibitors in type 2 diabetes: rationale and evidences

No single antidiabetic agent can correct all the pathophysiologic defects manifested in type 2 diabetes mellitus (T2DM) and, therefore, multiple agents are often required to achieve optimal glycemic control. Combination therapies, having different mechanisms of action, not only have the potential to complement their action, but may possess the properties to counter the undesired compensatory response. Recent finding suggests that sodium-glucose co-transporter-2 inhibitors (SGLT2i) increase endogenous glucose production (EGP) from liver, due to the increase in glucagon which may offset its glucose-lowering potential. In contrast, dipeptidyl peptidase-4 inhibitors (DPP4i) decrease glucagon and EGP. Especially in the light of this finding, combination therapies with SGLT2i and DPP4i are particularly appealing, and are expected to produce an additive effect. Indeed, studies find no drug-drug interaction between SGLT2i and DPP4i. Moreover, significant reduction in glycated hemoglobin has also been observed. This article aims to review the efficacy and safety of combination therapy of SGLT2i and DPP4i in T2DM.

Renal effects of canagliflozin in type 2 diabetes mellitus

BACKGROUND

Chronic kidney disease is commonly associated with type 2 diabetes mellitus (T2DM) and may impact the efficacy and safety of glucose-lowering therapies. Canagliflozin, a sodium glucose co-transporter 2 inhibitor, reduces blood glucose levels in patients with T2DM by lowering the renal threshold for glucose, thereby promoting urinary glucose excretion. This review describes the pharmacology, efficacy and safety of canagliflozin according to kidney function in participants with T2DM.

METHODS

Published articles that reported efficacy, safety and pharmacokinetics/pharmacodynamics data for canagliflozin in patients with T2DM and impaired renal function, and renal safety data with canagliflozin in various populations of patients with T2DM through May 2015 were included.

RESULTS

Early transient reductions in estimated glomerular filtration rate were observed with canagliflozin; these changes generally stabilized or attenuated over time and reversed after discontinuation, suggesting no renal (glomerular or tubular) damage with canagliflozin treatment. Urinary albumin-to-creatinine ratios were reduced with canagliflozin. Canagliflozin was generally well tolerated in patients with normal or mild to moderately impaired renal function, with a modestly higher incidence of renal-related adverse events and volume depletion-related adverse events in patients with moderate renal impairment. Adverse events related to potassium elevations were infrequent with canagliflozin 100 mg regardless of kidney function status; however, patients with moderately impaired kidney function experienced hyperkalemia more frequently with canagliflozin 300 mg compared with patients treated with either canagliflozin 100 mg or placebo. Canagliflozin was not associated with increased cardiovascular risk across studies; however, relatively few events among patients with impaired renal function meant that the analysis was not adequately powered to examine this outcome, and results from separate trials are awaited.

CONCLUSIONS

Overall, canagliflozin is associated with small, transient changes in kidney function, and is well tolerated in patients with T2DM with varying kidney function status.

Dapagliflozin combination therapy in type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a progressive disease, and most patients ultimately require two or more antidiabetes drugs in addition to lifestyle changes to achieve and maintain glycemic control. Current consensus statements and guidelines recommend metformin as first-line pharmacotherapy for the treatment of T2DM in most patients. When glycemic control cannot be maintained with metformin alone, the sequential, stepwise addition of other agents is recommended. Agents such as thiazolidinediones or sulfonylureas have typically been added to metformin therapy. Although effective in reducing glycated hemoglobin, these drugs are often associated with adverse effects, most notably weight gain, and in the case of sulfonylureas, hypoglycemia. Sodium-glucose cotransporter 2 inhibitors, such as dapagliflozin, are the newest class of antidiabetes drugs approved for the treatment of T2DM. Dapagliflozin effectively improves glycemic control by increasing the renal excretion of excess glucose. In clinical trials, dapagliflozin has been well tolerated and has additional benefits of weight loss, low risk of hypoglycemia and reduction in blood pressure. This review discusses the clinical evidence and rationale for the use of dapagliflozin as add-on therapy in T2DM. The results suggest that dapagliflozin add-on therapy is a promising new treatment option for a wide range of patients with T2DM. Results from an ongoing cardiovascular outcomes trial are needed to establish the long-term safety of dapagliflozin.

Combination therapy in type 2 diabetes mellitus: adding empagliflozin to basal insulin

Type 2 diabetes mellitus (T2DM) management is complex, with few patients successfully achieving recommended glycemic targets with monotherapy, most progressing to combination therapy, and many eventually requiring insulin. Sodium glucose cotransporter 2 (SGLT2) inhibitors are an emerging class of antidiabetes agents with an insulin-independent mechanism of action, making them suitable for use in combination with any other class of antidiabetes agents, including insulin. This review evaluates a 78-week, randomized, double-blind, placebo-controlled trial investigating the impact of empagliflozin, an SGLT2 inhibitor, as add-on to basal insulin in patients with inadequate glycemic control on basal insulin, with or without metformin and/or a sulfonylurea. Empagliflozin added on to basal insulin resulted in significant and sustained reductions in glycated hemoglobin (HbA1c) levels compared with placebo. Empagliflozin has previously been shown to induce weight loss, and was associated with sustained weight loss in this study. This combination therapy was well tolerated, with similar levels of hypoglycemic adverse events in the empagliflozin and placebo groups over the 78-week treatment period. Urinary tract infections and genital infections, side effects associated with SGLT2 inhibitors, were reported more commonly in the empagliflozin group; however, such events led to treatment discontinuation in very few patients. These findings suggest that, with their complementary mechanisms of action, empagliflozin added on to basal insulin may be a useful treatment option in patients on basal insulin who need additional glycemic control without weight gain.

Empagliflozin in the treatment of type 2 diabetes: evidence to date

In the last decade, researchers have gained a greater understanding of the pathophysiologic mechanisms of type 2 diabetes as a chronic and progressive disease. One of the more recent treatment targets is the kidney. The kidneys become maladaptive in diabetes by increasing the reabsorption of glucose above the normal physiologic renal threshold. This discovery has led to the development of the sodium/glucose cotransporter 2 inhibitors (SGLT2). These agents readjust the renal threshold for glucose reabsorption to a lower level and decrease glucose reabsorption, while increasing urinary glucose when the glucose is above the renal threshold and subsequently lowering plasma glucose. The mechanism of action of the SGLT2 inhibitors is insulin independent, which makes them a novel treatment of diabetes. At the time of preparation of this manuscript, there were three SGLT2 inhibitors available in the US. This manuscript focuses on empagliflozin, the newest SGLT2 inhibitor, the trials in its development, and the clinical data available to date. Further, the authors propose future applications of empagliflozin, including in the treatment of type 1 diabetes, and its potential role in renoprotection.

SGLT2 inhibition: efficacy and safety in type 2 diabetes treatment

INTRODUCTION

Inhibitors of sodium-glucose cotransporters type 2 (SGLT2) offer a new opportunity for the management of type 2 diabetes mellitus. These agents reduce hyperglycemia by decreasing the renal glucose threshold and thereby increasing urinary glucose excretion. Subsequent reduction of glucotoxicity improves beta-cell sensitivity to glucose and tissue insulin sensitivity.

AREAS COVERED

This article analyzes the efficacy and safety data of canagliflozin, dapagliflozin and empagliflozin in randomized controlled trials of 24 - 104 weeks duration, compared with placebo or an active comparator, in patients treated with diet/exercise, metformin, dual oral therapy or insulin.

EXPERT OPINION

SGLT2 inhibitors significantly and consistently reduce glycated hemoglobin, with a minimal risk of hypoglycemia. The improvement of glucose control is similar or slightly better compared with metformin, sulfonylureas or sitagliptin, with the add-on value of significant reductions in body weight and blood pressure. However, caution is recommended in fragile elderly patients and patients with chronic kidney disease. An increased risk of genital mycotic infections is observed, but urinary tract infections are rare. Concern about an unexpected risk of euglycemic ketoacidosis has been recently reported. A possible renal protection deserves further attention. A remarkable reduction in cardiovascular mortality was reported in EMPA-REG OUTCOME with empagliflozin.

Better response to the SGLT2 inhibitor dapagliflozin in young adults with type 2 diabetes

BACKGROUND AND AIM

A variation of the response to Sodium glucose co-transporter 2 (SGLT2) inhibitors with age has not been investigated in patients with diabetes. The aim of this study was to assess renal threshold of glucose (RTg) before and after administration of an SGLT2 inhibitor in young adult patients (≤40 years) and older adult patients (>40 years) with type 2 diabetes (T2DM).

SUBJECTS AND METHODS

Twenty Japanese patients with T2DM were enrolled. Baseline data were obtained on the first day and dapagliflozin (5 mg) was administered at 6:00 on the second day. Glucose excursions were assessed by continuous glucose monitoring and urine samples were collected every hour during the daytime (7:00 to 15:00) on both days. RTg was estimated from the regression line of the scatter plot of the hourly mean glucose concentrations.

RESULTS

After a single dose of dapagliflozin, RTg decreased from 121.5 to 6.1 mg/dl in the young adult group and from 151.0 mg/dl to -15.8 mg/dl in the older group. After dapagliflozin, the slope of the regression line was significantly steeper in the young adult group.

CONCLUSION

Dapagliflozin was more effective in young patients because they showed a larger response of urinary glucose excretion.

Efficacy and safety of dapagliflozin, a sodium glucose cotransporter 2 (SGLT2) inhibitor, in diabetes mellitus

Although antidiabetic agents have been developed to target one or more of the core defects of type 2 diabetes mellitus (T2DM), many patients do not achieve glycemic goals. Inhibition of the sodium-glucose cotransporter 2 (SGLT2) induces glycosuria, reduces glucose toxicity and improves insulin sensitivity and β-cell function. As the mechanism of action of SGLT2 inhibitors is different from other agents and completely insulin-independent, the use of these drugs might potentially be efficacious alone or in combination with any other antidiabetic drug, including insulin. Dapagliflozin is a highly selective and reversible SGLT2 inhibitor approved for use in adult patients with T2DM as monotherapy in patients intolerant of metformin or as adjunctive therapy in patients inadequately controlled on existing antidiabetic medications, including insulin. A literature search conducted using PubMed identified key publications related to the use of dapagliflozin in the treatment of patients with diabetes mellitus. No date limits were applied. This review focuses on the safety and efficacy of this SGLT2 inhibitor. Dapagliflozin produces dose-related reductions in glycosylated hemoglobin (HbA1c) as monotherapy and as add-on to other antidiabetic agents, with significant reductions in body weight. Hypoglycemia is uncommon. Preliminary data from a phase 2 pharmacokinetic/pharmacodynamic study suggest that dapagliflozin may also improve glycemic control in patients with type 1 diabetes mellitus. Clinical trials published to date show that dapagliflozin is safe and effective as monotherapy or as an add-on to insulin or oral antidiabetic agents in patients with T2DM.

The potential role of sodium glucose co-transporter 2 inhibitors in the early treatment of type 2 diabetes mellitus

BACKGROUND

Sodium glucose co-transporter 2 (SGLT2) inhibitors are a new class of pharmacologic agents developed for the treatment of type 2 diabetes mellitus (T2DM). Their unique mechanism of action is independent of pancreatic beta-cell function or the degree of insulin resistance, giving these agents the potential for use in combination with any of the existing classes of glucose-lowering agents, including insulin. This makes SGLT2 inhibitors an option for patients with long-standing T2DM, but they also have a promising role for early intervention in T2DM, and that role is explored in this review.

METHODS

A literature search was performed to identify relevant English language articles relating to SGLT2 inhibitors, particularly dapagliflozin, canagliflozin and empagliflozin.

RESULTS

Clinical trials of dapagliflozin, canagliflozin and empagliflozin, given as monotherapy or in combination with other glucose-lowering agents, reported clinically significant improvements in glycaemic control, body weight and systolic blood pressure. SGLT2 inhibitors were well tolerated and had a generally favourable safety profile. Few serious adverse events have been reported to date. The frequency of hypoglycaemic events was low, similar to that of placebo, and the choice of co-administered glucose-lowering agent was the major determinant of hypoglycaemic risk. Increased genital and urinary tract infections were consistently reported with SGLT2 inhibitors.

CONCLUSIONS

SGLT2 inhibitors, with their unique insulin-independent mode of action, could have a significant impact on the early management of T2DM, by addressing some of the specific risk factors associated with this disease. SGLT2 inhibitors induce beneficial changes in a number of cardiovascular risk factors, such as lowering blood pressure and body weight, in addition to improved glycaemic control, although information on clinical cardiovascular outcomes is currently limited.

Pharmacodynamics, efficacy and safety of sodium-glucose co-transporter type 2 (SGLT2) inhibitors for the treatment of type 2 diabetes mellitus

Inhibitors of sodium-glucose co-transporter type 2 (SGLT2) are proposed as a novel approach for the management of type 2 diabetes mellitus (T2DM). Several compounds are already available in many countries (dapagliflozin, canagliflozin, empagliflozin and ipragliflozin) and some others are in a late phase of development. The available SGLT2 inhibitors share similar pharmacokinetic characteristics, with a rapid oral absorption, a long elimination half-life allowing once-daily administration, an extensive hepatic metabolism mainly via glucuronidation to inactive metabolites, the absence of clinically relevant drug-drug interactions and a low renal elimination as parent drug. SGLT2 co-transporters are responsible for reabsorption of most (90 %) of the glucose filtered by the kidneys. The pharmacological inhibition of SGLT2 co-transporters reduces hyperglycaemia by decreasing renal glucose threshold and thereby increasing urinary glucose excretion. The amount of glucose excreted in the urine depends on both the level of hyperglycaemia and the glomerular filtration rate. Results of numerous placebo-controlled randomised clinical trials of 12-104 weeks duration have shown significant reductions in glycated haemoglobin (HbA1c), resulting in a significant increase in the proportion of patients reaching HbA1c targets, and a significant lowering of fasting plasma glucose when SGLT2 inhibitors were administered as monotherapy or in addition to other glucose-lowering therapies including insulin in patients with T2DM. In head-to-head trials of up to 2 years, SGLT2 inhibitors exerted similar glucose-lowering activity to metformin, sulphonylureas or sitagliptin. The durability of the glucose-lowering effect of SGLT2 inhibitors appears to be better; however, this remains to be more extensively investigated. The risk of hypoglycaemia was much lower with SGLT2 inhibitors than with sulphonylureas and was similarly low as that reported with metformin, pioglitazone or sitagliptin. Increased renal glucose elimination also assists weight loss and could help to reduce blood pressure. Both effects were very consistent across the trials and they represent some advantages for SGLT2 inhibitors when compared with other oral glucose-lowering agents. The pharmacodynamic response to SGLT2 inhibitors declines with increasing severity of renal impairment, and prescribing information for each SGLT2 inhibitor should be consulted regarding dosage adjustments or restrictions in moderate to severe renal dysfunction. Caution is also recommended in the elderly population because of a higher risk of renal impairment, orthostatic hypotension and dehydration, even if the absence of hypoglycaemia represents an obvious advantage in this population. The overall effect of SGLT2 inhibitors on the risk of cardiovascular disease is unknown and will be evaluated in several ongoing prospective placebo-controlled trials with cardiovascular outcomes. The impact of SGLT2 inhibitors on renal function and their potential to influence the course of diabetic nephropathy also deserve more attention. SGLT2 inhibitors are generally well-tolerated. The most frequently reported adverse events are female genital mycotic infections, while urinary tract infections are less commonly observed and generally benign. In conclusion, with their unique mechanism of action that is independent of insulin secretion and action, SGLT2 inhibitors are a useful addition to the therapeutic options available for the management of T2DM at any stage in the natural history of the disease. Although SGLT2 inhibitors have already been extensively investigated, further studies should even better delineate the best place of these new glucose-lowering agents in the already rich armamentarium for the management of T2DM.

Renal sodium-glucose cotransporter inhibition in the management of type 2 diabetes mellitus

Hyperglycemia is the primary factor responsible for the microvascular, and to a lesser extent macrovascular, complications of diabetes. Despite this well-established relationship, approximately half of all type 2 diabetic patients in the US have a hemoglobin A1c (HbA1c) ≥7.0%. This is associated in part with the side effects, i.e., weight gain and hypoglycemia, of currently available antidiabetic agents and in part with the failure to utilize medications that reverse the basic pathophysiological defects present in patients with type 2 diabetes. The kidney has been shown to play a central role in the development of hyperglycemia by excessive production of glucose throughout the sleeping hours and enhanced reabsorption of filtered glucose by the renal tubules secondary to an increase in the threshold at which glucose spills into the urine. Recently, a new class of antidiabetic agents, the sodium-glucose cotransporter 2 (SGLT2) inhibitors, has been developed and approved for the treatment of patients with type 2 diabetes. In this review, we examine their mechanism of action, efficacy, safety, and place in the therapeutic armamentarium. Since the SGLT2 inhibitors have a unique mode of action that differs from all other oral and injectable antidiabetic agents, they can be used at all stages of the disease and in combination with all other antidiabetic medications.

Sodium-glucose cotransporter-2 inhibition and the potential for renal protection in diabetic nephropathy

PURPOSE OF REVIEW

Renal hyperfiltration has been used as a surrogate marker for increased intraglomerular pressure in patients with diabetes mellitus. Previous human investigation examining the pathogenesis of hyperfiltration has focused on the role of neurohormones such as the renin-angiotensin-aldosterone system (RAAS). Unfortunately, RAAS blockade does not completely attenuate hyperfiltration or diabetic kidney injury. More recent work has therefore investigated the contribution of renal tubular factors, including the sodium-glucose cotransporter, to the hyperfiltration state, which is the topic of this review.

RECENT FINDINGS

Novel sodium-glucose cotransporter-2 (SGLT2) inhibitors reduce proximal tubular sodium reabsorption, thereby increasing distal sodium delivery to the macula densa, causing tubuloglomerular feedback, afferent vasoconstriction and decreased hyperfiltration in animals. In humans, SGLT2 inhibition was recently shown to reduce hyperfiltration in normotensive, normoalbuminuric patients with type 1 diabetes. In clinical trials of type 2 diabetes, SGLT2 is associated with significant renal effects, including modest, acute declines in estimated glomerular filtration rate followed by the maintenance of stable renal function, and reduced albuminuria.

SUMMARY

Existing data are supportive of a potential renal-protective role for SGLT2 inhibition in patients with diabetes. Dedicated renal outcome trials are ongoing and have the potential to change the clinical practice.

A comprehensive review of the pharmacodynamics of the SGLT2 inhibitor empagliflozin in animals and humans

Empagliflozin (formerly known as BI 10773) is a potent, competitive, and selective inhibitor of the sodium glucose transporter SGLT2, which mediates glucose reabsorption in the early proximal tubule and most of the glucose reabsorption by the kidney, overall. Accordingly, empagliflozin treatment increased urinary glucose excretion. This has been observed across multiple species including humans and was reported under euglycemic conditions, in obesity and, most importantly, in type 2 diabetic patients and multiple animal models of type 2 diabetes and of type 1 diabetes. This led to a reduction in blood glucose, smaller blood glucose excursions during oral glucose tolerance tests, and, upon chronic treatment, a reduction in HbA1c in animal models and patients. In rodents, such effects were observed in early and late phases of experimental diabetes and were associated with preservation of pancreatic β-cell function. Combination studies in animals demonstrated that beneficial metabolic effects of empagliflozin may also manifest when added to other types of anti-hyperglycemic treatments including linagliptin and pioglitazone. While some anti-hyperglycemic drugs lead to weight gain, empagliflozin treatment was associated with reduced body weight in normoglycemic obese and non-obese animals despite an increased food intake, largely due to a loss of adipose tissue; on the other hand, empagliflozin preserved body weight in models of type 1 diabetes. Empagliflozin improved endothelial dysfunction in diabetic rats and arterial stiffness, reduced blood pressure in diabetic patients, and attenuated early signs of nephropathy in diabetic animal models. Taken together, the SGLT2 inhibitor empagliflozin improves glucose metabolism by enhancing urinary glucose excretion; upon chronic administration, at least in animal models, the reductions in blood glucose levels are associated with beneficial effects on cardiovascular and renal complications of diabetes.

Type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is an expanding global health problem, closely linked to the epidemic of obesity. Individuals with T2DM are at high risk for both microvascular complications (including retinopathy, nephropathy and neuropathy) and macrovascular complications (such as cardiovascular comorbidities), owing to hyperglycaemia and individual components of the insulin resistance (metabolic) syndrome. Environmental factors (for example, obesity, an unhealthy diet and physical inactivity) and genetic factors contribute to the multiple pathophysiological disturbances that are responsible for impaired glucose homeostasis in T2DM. Insulin resistance and impaired insulin secretion remain the core defects in T2DM, but at least six other pathophysiological abnormalities contribute to the dysregulation of glucose metabolism. The multiple pathogenetic disturbances present in T2DM dictate that multiple antidiabetic agents, used in combination, will be required to maintain normoglycaemia. The treatment must not only be effective and safe but also improve the quality of life. Several novel medications are in development, but the greatest need is for agents that enhance insulin sensitivity, halt the progressive pancreatic β-cell failure that is characteristic of T2DM and prevent or reverse the microvascular complications. For an illustrated summary of this Primer, visit: http://go.nature.com/V2eGfN.

Metabolic effects of SGLT-2 inhibitors beyond increased glucosuria: A review of the clinical evidence

Sodium-glucose cotransporter type 2 (SGLT-2) inhibitors (canagliflozin, dapagliflozin, empagliflozin) are new glucose-lowering agents that exert their therapeutic activity independently of insulin by facilitating glucose excretion through the kidneys. However, this simple renal mechanism that results in sustained glucose urinary loss leads to more complex indirect metabolic effects. First, by reduction of chronic hyperglycaemia and attenuation of glucose toxicity, SGLT-2 inhibitors can improve both insulin secretion by beta cells and peripheraltissue insulin sensitivity. In the case of canagliflozin, because of low-potency SGLT1 inhibition, a non-renal (intestinal) effect may also be considered, which may contribute to better control of postprandial hyperglycaemia, although this contribution remains to be better analyzed in humans. Second, chronic glucose loss most probably leads to compensatory mechanisms. One of them, although not well evidenced in humans, might involve an increase in energy intake, an effect that may limit weight loss in the long run. Another could be an increase in endogenous glucose production, most probably driven by increased glucagon secretion, which may somewhat attenuate the glucoselowering effect. Nevertheless, despite these compensatory mechanisms and most probably because of the positive effects of the reduction in glucotoxicity, SGLT-2 inhibitors exert clinically relevant glucose-lowering activity while promoting weight loss, a unique dual effect among oral antidiabetic agents. Furthermore, the combination of SGLT-2 inhibitors with other drugs that either have anorectic effects (such as incretin-based therapies) or reduce hepatic glucose output (like metformin) and, thus, may dampen these two compensatory mechanisms appears appealing for the management of type 2 diabetes mellitus.

Cardiovascular Risk in Diabetes Mellitus: Complication of the Disease or of Antihyperglycemic Medications

Cardiovascular disease is the principal complication and the leading cause of death for patients with diabetes (DM). The efficacy of antihyperglycemic treatments on cardiovascular disease risk remains uncertain. Cardiovascular risk factors are affected by antihyperglycemic medications, as are many intermediate markers of cardiovascular disease. Here we summarize the evidence assessing the cardiovascular effects of antihyperglycemic medications with regard to risk factors, intermediate markers of disease, and clinical outcomes.

Central obesity, type 2 diabetes and insulin: exploring a pathway full of thorns

The prevalence of type 2 diabetes (T2D) is rapidly increasing. This is strongly related to the contemporary lifestyle changes that have resulted in increased rates of overweight individuals and obesity. Central (intra-abdominal) obesity is observed in the majority of patients with T2D. It is associated with insulin resistance, mainly at the level of skeletal muscle, adipose tissue and liver. The discovery of macrophage infiltration in the abdominal adipose tissue and the unbalanced production of adipocyte cytokines (adipokines) was an essential step towards novel research perspectives for a better understanding of the molecular mechanisms governing the development of insulin resistance. Furthermore, in an obese state, the increased cellular uptake of non-esterified fatty acids is exacerbated without any subsequent β-oxidation. This in turn contributes to the accumulation of intermediate lipid metabolites that cause defects in the insulin signaling pathway. This paper examines the possible cellular mechanisms that connect central obesity with defects in the insulin pathway. It discusses the discrepancies observed from studies organized in cell cultures, animal models and humans. Finally, it emphasizes the need for therapeutic strategies in order to achieve weight reduction in overweight and obese patients with T2D.

Impact of glucose-lowering drugs on cardiovascular disease in type 2 diabetes

Type 2 diabetes mellitus (T2DM) is characterized by multiple pathophysiologic abnormalities. With time, multiple glucose-lowering medications are commonly required to reduce and maintain plasma glucose concentrations within the normal range. Type 2 diabetes mellitus individuals also are at a very high risk for microvascular complications and the incidence of heart attack and stroke is increased two- to three-fold compared with non-diabetic individuals. Therefore, when selecting medications to normalize glucose levels in T2DM patients, it is important that the agent not aggravate, and ideally even improve, cardiovascular risk factors (CVRFs) and reduce cardiovascular morbidity and mortality. In this review, we examine the effect of oral (metformin, sulfonylureas, meglitinides, thiazolidinediones, DPP4 inhibitors, SGLT2 inhibitors, and α-glucosidase inhibitors) and injectable (glucagon-like peptide-1 receptor agonists and insulin) glucose-lowering drugs on established CVRFs and long-term studies of cardiovascular outcomes. Firm evidence that in T2DM cardiovascular disease can be reversed or prevented by improving glycaemic control is still incomplete and must await large, long-term clinical trials in patients at low risk using modern treatment strategies, i.e., drug combinations designed to maximize HbA1c reduction while minimizing hypoglycaemia and excessive weight gain.

Dapagliflozin lowers plasma glucose concentration and improves β-cell function

BACKGROUND

β-Cell dysfunction is a core defect in T2DM, and chronic, sustained hyperglycemia has been implicated in progressive β-cell failure, ie, glucotoxicity. The aim of the present study was to examine the effect of lowering the plasma glucose concentration with dapagliflozin, a glucosuric agent, on β-cell function in T2DM individuals.

RESEARCH DESIGN AND METHODS

Twenty-four subjects with T2DM received dapagliflozin (n = 16) or placebo (n = 8) for 2 weeks, and a 75-g oral glucose tolerance test (OGTT) and insulin clamp were performed before and after treatment. Plasma glucose, insulin, and C-peptide concentrations were measured during the OGTT.

RESULTS

Dapagliflozin significantly lowered both the fasting and 2-hour plasma glucose concentrations and the incremental area under the plasma glucose concentration curve (ΔG0-120) during OGTT by -33 ± 5 mg/dL, -73 ± 9 mg/dL, and -60 ± 12 mg/dL · min, respectively, compared to -13 ± 9, -33 ± 13, and -18 ± 9 reductions in placebo-treated subjects (both P < .01). The incremental area under the plasma C-peptide concentration curve tended to increase in dapagliflozin-treated subjects, whereas it did not change in placebo-treated subjects. Thus, ΔC-Pep0-120/ΔG0-120 increased significantly in dapagliflozin-treated subjects, whereas it did not change in placebo-treated subjects (0.019 ± 0.005 vs 0.002 ± 0.006; P < .01). Dapagliflozin significantly improved whole-body insulin sensitivity (insulin clamp). Thus, β-cell function, measured as ΔC-Pep0-120/ ΔG0-120 ÷ insulin resistance, increased by 2-fold (P < .01) in dapagliflozin-treated vs placebo-treated subjects.

CONCLUSION

Lowering the plasma glucose concentration with dapagliflozin markedly improves β-cell function, providing strong support in man for the glucotoxic effect of hyperglycemia on β-cell function.

Continual evolution of type 2 diabetes: an update on pathophysiology and emerging treatment options

Diabetes is a complex and progressive disease that has a major societal and economic impact. The most common form of diabetes, type 2 diabetes mellitus (T2DM), is a multifactorial disease, the pathophysiology of which involves not only the pancreas but also the liver, skeletal muscle, adipose tissue, gastrointestinal tract, brain, and kidney. Novel therapies with mechanisms of action that are different from most existing drugs are emerging. One such class consists of compounds that inhibit renal sodium-glucose cotransporter 2, which is responsible for the bulk of glucose reabsorption by the kidneys. This new class of compounds improves glycemic control independently of insulin and promotes weight reduction, providing an additional tool to treat patients with T2DM. This review discusses the underlying pathophysiology of T2DM, clinical guidelines, and available and emerging treatment options, with particular emphasis on sodium-glucose cotransporter 2 inhibitors.

Development and application of a fluorescent glucose uptake assay for the high-throughput screening of non-glycoside SGLT2 inhibitors

Sodium-dependent glucose co-transporter 2 (SGLT2) inhibitors are of current interest as a treatment for type 2 diabetes. Efforts have been made to discover phlorizin-related glycosides with good SGLT2 inhibitory activity. To increase structural diversity and better understand the role of non-glycoside SGLT2 inhibitors on glycemic control, we initiated a research program to identify non-glycoside hits from high-throughput screening. Here, we report the development of a novel, fluorogenic probe-based glucose uptake system based on a Cu(I)-catalyzed [3+2] cycloaddition. The safer processes and cheaper substances made the developed assay our first priority for large-scale primary screening as compared to the well-known [(14)C]-labeled α-methyl-D-glucopyranoside ([(14)C]-AMG) radioactive assay. This effort culminated in the identification of a benzimidazole, non-glycoside SGLT2 hit with an EC50 value of 0.62 μM by high-throughput screening of 41,000 compounds.