Ipragliflozin and other sodium-glucose cotransporter-2 (SGLT2) inhibitors in the treatment of type 2 diabetes: preclinical and clinical data

Role of diet and exercise in aging, Alzheimer's disease, and other chronic diseases

Alzheimer's disease (AD) is a progressive neurodegenerative disease, characterized by memory loss and multiple cognitive impairments. Genetic mutations cause a small proportion (1-2%) of early-onset AD, with mutations in amyloid precursor protein (APP), presenilin 1 (PS1) and presenilin 2 (PS2). Major contributing factors of late-onset AD are ApoE4 genotype, traumatic brain injury, diabetes, obesity, hypertension, cardiovascular conditions, in addition to lifestyle factors, such as unhealthy diet and lack of physical exercise. Disease progression can be delayed and/or prevented to a greater extent by adopting healthy lifestyle with balanced and antioxidant enriched diet and daily exercise. The interaction and interplay of diet, exercise, age, and pharmacological interventions holds a crucial role in the progression, pathogenesis and management of AD and its comorbidities, including diabetes, obesity, hypertension and cardiovascular conditions. Antioxidant enriched diet contributes to brain health, glucose control, weight management, and cardiovascular well-being. Regular exercise removes toxins including free radicals and enhances insulin sensitivity, and supports cardiovascular function. In the current article, we discussed, the role of diet, and exercise in aging, AD and other conditions including diabetes, obesity, hypertension, cardiovascular conditions. This article also highlights the impact of medication, socioeconomic and lifestyle factors, and pharmacological interventions. These aspects were discussed in different races and ethnic groups in Texas, and the US.

Sodium-glucose cotransporter-2 inhibitors improve FibroScan-aspartate aminotransferase scores in patients with nonalcoholic fatty liver disease complicated by type 2 diabetes

BACKGROUND AND AIM

Nonalcoholic fatty liver disease (NAFLD) is a chronic liver disease caused by excessive lipid accumulation in the liver, and its global incidence is increasing. Sodium-glucose cotransporter-2 inhibitors (SGLT2is) are oral antidiabetes drugs that promote glucose excretion into the urine and have been reported to exert therapeutic effects in NAFLD, but liver stiffness measurements (LSMs) determined by transient elastography are inconsistent. In addition, the effects of SGLT2is on the FibroScan-aspartate aminotransferase (FAST) scores have not been reported. We evaluated the effect of SGLT2is on patients with NAFLD complicated by type 2 diabetes using biochemical tests, transient elastography, and FAST scores.

METHODS

Fifty-two patients with type 2 diabetes complicated by NAFLD who started SGLT2i treatment between 2014 and 2020 at our hospital were selected from the database. Pre- and post-treatment serum parameters, transient elastography, and FAST scores were compared.

RESULTS

After 48 weeks of SGLT2i treatment, body weight, fasting blood glucose, hemoglobin A1c, AST, alanine aminotransferase, gamma-glutamyltransferase, uric acid, fibrosis-4 index, and AST to platelet ratio index improved. Median LSM decreased from 7.0 kPa to 6.2 kPa ( P  = 0.023) and the median controlled attenuation parameter decreased from 304 dB/m to 283 dB/m ( P  = 0.022). Median FAST score decreased from 0.40 to 0.22 ( P  < 0.001), and the number of cases with a cutoff value of ≥0.35 decreased from 15 to 6 ( P  = 0.001).

CONCLUSION

SGLT2i use not only improves weight loss and blood glucose levels but also improves hepatic fibrosis by ameliorating hepatic steatosis and inflammation.

Canagliflozin protects the cardiovascular system through effects on the gut environment in non-diabetic nephrectomized rats

BACKGROUND

The gut produces toxins that contribute to the cardiovascular complications of chronic kidney disease. Canagliflozin, a sodium glucose cotransporter (SGLT) 2 inhibitor that is used as an anti-diabetic drug, has a weak inhibitory effect against SGLT1 and may affect the gut glucose concentration and environment.

METHODS

Here, we determined the effect of canagliflozin on the gut microbiota and the serum gut-derived uremic toxin concentrations in 5/6th nephrectomized (Nx) rats.

RESULTS

Canagliflozin increased the colonic glucose concentration and restored the number of Lactobacillus bacteria, which was low in Nx rats. In addition, the expression of tight junction proteins in the ascending colon was low in Nx rats, and this was partially restored by canagliflozin. Furthermore, the serum concentrations of gut-derived uremic toxins were significantly increased by Nx and reduced by canagliflozin. Finally, the wall of the thoracic aorta was thicker and there was more cardiac interstitial fibrosis in Nx rats, and these defects were ameliorated by canagliflozin.

CONCLUSIONS

The increases in colonic glucose concentration, Lactobacillus numbers and tight junction protein expression, and the decreases in serum uremic toxin concentrations and cardiac interstitial fibrosis may have been caused by the inhibition of SGLT1 by canagliflozin because similar effects were not identified in tofogliflozin-treated rats.

The impact of SGLT2 inhibitors on αKlotho in renal MDCK and HK-2 cells

αKlotho is a transmembrane protein predominantly expressed in the kidney serving as a co-receptor for phosphate homeostasis-regulating hormone FGF23 and has an extracellular domain that can be cleaved off and is a hormone. αKlotho deficiency results in accelerated aging and early onset of aging-associated diseases while its overexpression strongly expands the lifespan of mice. Moreover, αKlotho exerts health-beneficial anti-inflammatory, anti-neoplastic, anti-fibrotic, and anti-oxidant effects. Higher αKlotho levels are associated with better outcomes in renal and cardiovascular diseases. SGLT2 inhibitors are novel drugs in the treatment of diabetes by inhibiting renal glucose transport and have additional nephro- and cardioprotective effects. We explored whether SGLT2 inhibitors affect αKlotho gene expression and protein secretion. Experiments were performed in renal MDCK and HK-2 cells, and αKlotho transcripts were determined by qRT-PCR and Klotho protein by ELISA. SGLT2 inhibitors canagliflozin, sotagliflozin, and dapagliflozin enhanced whereas empagliflozin reduced αKlotho gene expression in MDCK cells. By the same token, canagliflozin, sotagliflozin, dapagliflozin, but not empagliflozin down-regulated p65 subunit of pro-inflammatory NFκB. In HK-2 cells, all SGLT2 inhibitors reduced αKlotho transcripts. Canagliflozin and sotagliflozin, however, increased Klotho protein concentration in the cell culture supernatant, an effect paralleled by up-regulation of ADAM17. Taken together, our investigations demonstrate complex effects of different SGLT2 inhibitors on αKlotho gene expression and protein secretion in renal MDCK and HK-2 cells.

Kidney outcomes in patients with diabetes mellitus did not differ between individual sodium-glucose cotransporter-2 inhibitors

Data comparing kidney outcomes between individual sodium-glucose cotransporter-2 (SGLT2) inhibitors are limited. Here, we aimed to compare the subsequent risk of developing kidney outcomes between individual inhibitors. This would be the first study to compare kidney outcomes of patients with diabetes mellitus who were newly treated with individual SGLT2 inhibitors using a large-scale real-world dataset. To do this, we analyzed results from 12,100 patients with diabetes mellitus who were taking different SGLT2 inhibitors (2,573 with empagliflozin; 2,214 with dapagliflozin; 2,100 with canagliflozin; and 5,213 with other such inhibitors). The primary outcome was the rate of estimated glomerular filtration rate (eGFR) decline as assessed using a linear mixed-effects model with an unstructured covariance. The median age of the patients was 53 years, and 84.4% of the patients were men. The median fasting plasma glucose and HbA1c levels were 147 (interquartile range 126-178) mg/dL and 7.5 (6.9-8.4)%, respectively. The median eGFR was 78 mL/min/1.73 m² (interquartile range 68-90). The mean follow-up period was 773 days. The annual eGFR slopes of empagliflozin, dapagliflozin, canagliflozin, and other SGLT2 inhibitors were -1.15 (95% confidence interval, -1.33 to -0.96), -1.14 (-1.32 to -0.96), -1.24 (-1.44 to -1.04), and -1.06 (-1.18 to -0.94) ml/min/1.73 m², respectively. No significant interaction was detected between the SGLT2 inhibitors and time using a linear mixed-effects model. A multitude of sensitivity analyses confirmed the robustness of our primary results. Thus, we found that there was no significant difference in the annual eGFR decline slopes between patients taking different SGLT2 inhibitors.

Carbohydrate-based drugs launched during 2000-2021

Carbohydrates are fundamental molecules involved in nearly all aspects of lives, such as being involved in formating the genetic and energy materials, supporting the structure of organisms, constituting invasion and host defense systems, and forming antibiotics secondary metabolites. The naturally occurring carbohydrates and their derivatives have been extensively studied as therapeutic agents for the treatment of various diseases. During 2000 to 2021, totally 54 carbohydrate-based drugs which contain carbohydrate moities as the major structural units have been approved as drugs or diagnostic agents. Here we provide a comprehensive review on the chemical structures, activities, and clinical trial results of these carbohydrate-based drugs, which are categorized by their indications into antiviral drugs, antibacterial/antiparasitic drugs, anticancer drugs, antidiabetics drugs, cardiovascular drugs, nervous system drugs, and other agents.

Effects of Sodium-Glucose Cotransporter 2 Inhibitors on Water and Sodium Metabolism

Sodium-glucose cotransporter 2 (SGLT2) inhibitors exert hypoglycemic and diuretic effects by inhibiting the absorption of sodium and glucose from the proximal tubule. Currently available data indicate that SGLT2 inhibitors transiently enhance urinary sodium excretion and urinary volume. When combined with loop diuretics, SGLT2 inhibitors exert a synergistic natriuretic effect. The favorable diuretic profile of SGLT2 inhibitors may confer benefits to volume management in patients with heart failure but this natriuretic effect may not be the dominant mechanism for the superior long-term outcomes observed with these agents in patients with heart failure. The first part of this review explores the causes of transient natriuresis and the diuretic mechanisms of SGLT2 inhibitors. The second part provides an overview of the synergistic effects of combining SGLT2 inhibitors with loop diuretics, and the third part summarizes the mechanisms of cardiovascular protection associated with the diuretic effects of SGLT2 inhibitors.

Sodium-Glucose Cotransporter 2 Inhibitors and Cardiac Remodeling

Sodium-glucose cotransporter 2 (SGLT2) inhibitors have evident cardiovascular benefits in patients with type 2 diabetes with or at high risk for atherosclerotic cardiovascular disease, heart failure with reduced ejection fraction, heart failure with preserved ejection fraction (only empagliflozin and dapagliflozin have been investigated in this group so far), and chronic kidney disease. Prevention and reversal of adverse cardiac remodeling is one of the mechanisms by which SGLT2 inhibitors may exert cardiovascular benefits, especially heart failure-related outcomes. Cardiac remodeling encompasses molecular, cellular, and interstitial changes that result in favorable changes in the mass, geometry, size, and function of the heart. The pathophysiological mechanisms of adverse cardiac remodeling are related to increased apoptosis and necrosis, decreased autophagy, impairments of myocardial oxygen supply and demand, and altered energy metabolism. Herein, the accumulating evidence from animal and human studies is reviewed investigating the effects of SGLT2 inhibitors on these mechanisms of cardiac remodeling.

Effects of canagliflozin on human myocardial redox signalling: clinical implications

AIMS

Recent clinical trials indicate that sodium-glucose cotransporter 2 (SGLT2) inhibitors improve cardiovascular outcomes in heart failure patients, but the underlying mechanisms remain unknown. We explored the direct effects of canagliflozin, an SGLT2 inhibitor with mild SGLT1 inhibitory effects, on myocardial redox signalling in humans.

METHODS AND RESULTS

Study 1 included 364 patients undergoing cardiac surgery. Right atrial appendage biopsies were harvested to quantify superoxide (O2.-) sources and the expression of inflammation, fibrosis, and myocardial stretch genes. In Study 2, atrial tissue from 51 patients was used ex vivo to study the direct effects of canagliflozin on NADPH oxidase activity and nitric oxide synthase (NOS) uncoupling. Differentiated H9C2 and primary human cardiomyocytes (hCM) were used to further characterize the underlying mechanisms (Study 3). SGLT1 was abundantly expressed in human atrial tissue and hCM, contrary to SGLT2. Myocardial SGLT1 expression was positively associated with O2.- production and pro-fibrotic, pro-inflammatory, and wall stretch gene expression. Canagliflozin reduced NADPH oxidase activity via AMP kinase (AMPK)/Rac1signalling and improved NOS coupling via increased tetrahydrobiopterin bioavailability ex vivo and in vitro. These were attenuated by knocking down SGLT1 in hCM. Canagliflozin had striking ex vivo transcriptomic effects on myocardial redox signalling, suppressing apoptotic and inflammatory pathways in hCM.

CONCLUSIONS

We demonstrate for the first time that canagliflozin suppresses myocardial NADPH oxidase activity and improves NOS coupling via SGLT1/AMPK/Rac1 signalling, leading to global anti-inflammatory and anti-apoptotic effects in the human myocardium. These findings reveal a novel mechanism contributing to the beneficial cardiac effects of canagliflozin.

SGLT2 Inhibitors and Their Mode of Action in Heart Failure-Has the Mystery Been Unravelled?

PURPOSE OF REVIEW

SGLT2 inhibitors (SGLT2i) are new drugs for patients with heart failure (HF) irrespective of diabetes. However, the mechanisms of SGLT2i in HF remain elusive. This article discusses the current clinical evidence for using SGLT2i in different types of heart failure and provides an overview about the possible underlying mechanisms.

RECENT FINDINGS

Clinical and basic data strongly support and extend the use of SGLT2i in HF. Improvement of conventional secondary risk factors is unlikely to explain the prognostic benefits of these drugs in HF. However, different multidirectional mechanisms of SGLT2i could improve HF status including volume regulation, cardiorenal mechanisms, metabolic effects, improved cardiac remodelling, direct effects on cardiac contractility and ion-homeostasis, reduction of inflammation and oxidative stress as well as an impact on autophagy and adipokines. Further translational studies are needed to determine the mechanisms of SGLT2i in HF. However, basic and clinical evidence encourage the use of SGLT2i in HFrEF and possibly HFpEF.

New Aspects of Diabetes Research and Therapeutic Development

Both type 1 and type 2 diabetes mellitus are advancing at exponential rates, placing significant burdens on health care networks worldwide. Although traditional pharmacologic therapies such as insulin and oral antidiabetic stalwarts like metformin and the sulfonylureas continue to be used, newer drugs are now on the market targeting novel blood glucose-lowering pathways. Furthermore, exciting new developments in the understanding of beta cell and islet biology are driving the potential for treatments targeting incretin action, islet transplantation with new methods for immunologic protection, and the generation of functional beta cells from stem cells. Here we discuss the mechanistic details underlying past, present, and future diabetes therapies and evaluate their potential to treat and possibly reverse type 1 and 2 diabetes in humans. SIGNIFICANCE STATEMENT: Diabetes mellitus has reached epidemic proportions in the developed and developing world alike. As the last several years have seen many new developments in the field, a new and up to date review of these advances and their careful evaluation will help both clinical and research diabetologists to better understand where the field is currently heading.

Effects of SGLT2 inhibitor ipragliflozin alone and combined with pioglitazone on fluid retention in type 2 diabetic mice with NASH

Several antidiabetic agents, including thiazolidinediones and sodium-glucose cotransporter (SGLT) 2 inhibitors, attenuate the symptoms of nonalcoholic steatohepatitis (NASH). However, thiazolidinediones have serious side effects such as fluid retention and increased risk of congestive heart failure. We examined the effects of SGLT2 inhibitor ipragliflozin, pioglitazone, and ipragliflozin + pioglitazone on fluid retention in type 2 diabetic mice with NASH. Four-week repeated administration of pioglitazone caused significant increases in heart weight (31% increase in 30 mg/kg pioglitazone-treated group compared to vehicle-treated group) concomitant with fluid retention, as estimated by a decrease in plasma osmolality and increase in water intake/urine volume ratio. In addition, pioglitazone significantly increased (by 1.5 to 2-fold) mRNA expression of α, β, and γ subtypes of ENaC and AQP2 and 3 subtypes in the renal medulla. Thus, pioglitazone-induced fluid retention may arise from enhanced reabsorption of sodium and water associated with increased expression of these channels in the kidney. In contrast, ipragliflozin alone did not induce these symptoms and did not affect ENaC or AQP expression. Combination treatment with ipragliflozin + pioglitazone attenuated these symptoms by ipragliflozin-induced osmotic diuresis. These findings demonstrate that treatment with ipragliflozin monotherapy or coadministered with pioglitazone may be a potential therapeutic option for the treatment of type 2 diabetes with NASH without fluid retention as a side effect.

Pharmacokinetics, pharmacodynamics and tolerability of single and multiple doses of janagliflozin, a sodium-glucose co-transporter-2 inhibitor, in Chinese people with type 2 diabetes mellitus

AIMS

To evaluate the pharmacokinetic (PK) and pharmacodynamic (PD) characteristics, and tolerability of janagliflozin, a novel sodium-glucose co-transporter-2 inhibitor, in Chinese people with type 2 diabetes mellitus (T2DM).

MATERIALS AND METHODS

In this study, 36 people with T2DM were randomly assigned in a 1:1:1:1 ratio to receive janagliflozin 25 mg, janagliflozin 50 mg, dapagliflozin 10 mg or placebo. Participants received a single dose on day 1, and were treated once daily from day 4 to day 17.

RESULTS

Following oral administration, janagliflozin was rapidly absorbed, reaching C_max at 2 hours. The mean half-life (t_1/2 ) at steady state was approximately 21 to 23 hours. There was no significant accumulation with multiple doses (accumulation factor < 2). In participants treated with janagliflozin 25 mg, janagliflozin 50 mg, dapagliflozin 10 mg or placebo, change in mean 24-hour urinary glucose excretion from baseline was 92.35, 94.17, 87.61 and 6.26 g after multiple doses, and change in mean fasting plasma glucose level from baseline to day 17 was -2.18, -2.66, -2.79 and 1.70%, respectively. Most adverse events (AEs) were mild or moderate with no deaths, serious AEs, or discontinuations due to AEs.

CONCLUSIONS

Single and multiple oral administration (14 days) of janagliflozin 25 mg and 50 mg exhibited favourable PK, PD and tolerability profiles in Chinese people with T2DM, which were comparable to those of dapagliflozin 10 mg. Janagliflozin 25 mg and 50 mg are recommended for further clinical investigation.

Glucose transporters in pancreatic islets

The fine-tuning of glucose uptake mechanisms is rendered by various glucose transporters with distinct transport characteristics. In the pancreatic islet, facilitative diffusion glucose transporters (GLUTs), and sodium-glucose cotransporters (SGLTs) contribute to glucose uptake and represent important components in the glucose-stimulated hormone release from endocrine cells, therefore playing a crucial role in blood glucose homeostasis. This review summarizes the current knowledge about cell type-specific expression profiles as well as proven and putative functions of distinct GLUT and SGLT family members in the human and rodent pancreatic islet and further discusses their possible involvement in onset and progression of diabetes mellitus. In context of GLUTs, we focus on GLUT2, characterizing the main glucose transporter in insulin-secreting β-cells in rodents. In addition, we discuss recent data proposing that other GLUT family members, namely GLUT1 and GLUT3, render this task in humans. Finally, we summarize latest information about SGLT1 and SGLT2 as representatives of the SGLT family that have been reported to be expressed predominantly in the α-cell population with a suggested functional role in the regulation of glucagon release.

SGLT2 inhibitor ipragliflozin alone and combined with pioglitazone prevents progression of nonalcoholic steatohepatitis in a type 2 diabetes rodent model

Nonalcoholic steatohepatitis (NASH) has become the most common cause of chronic liver disease worldwide in recent years. The pathogenesis of NASH is closely linked to metabolic diseases such as insulin resistance, obesity, dyslipidemia, and type 2 diabetes. However, there is currently no pharmacological agent for preventing the progression of NASH. Sodium-glucose cotransporter (SGLT) 2 inhibitors increase urinary glucose excretion by inhibiting renal glucose reabsorption, and improve various pathological conditions of type 2 diabetes, including insulin resistance. In the present study, we examined the effects of ipragliflozin, a SGLT2-selective inhibitor, alone and in combination with pioglitazone on NASH in high-fat diet-fed KK/A^y type 2 diabetic mice. Type 2 diabetic mice with NASH exhibited steatosis, inflammation, and fibrosis in the liver as well as hyperglycemia, insulin resistance, and obesity, features that are observed in human NASH. Four-week repeated administration of ipragliflozin (0.1-3 mg/kg) led to significant improvements in hyperglycemia, insulin resistance, and obesity in addition to hyperlipidemia and liver injury including hepatic steatosis and fibrosis. Moreover, ipragliflozin reduced inflammation and oxidative stress in the liver. Repeated administration of pioglitazone (3-30 mg/kg) also significantly improved various parameters of diabetes and NASH, excluding obesity. Furthermore, combined treatment comprising ipragliflozin (1 mg/kg) and pioglitazone (10 mg/kg) additively improved these parameters. These findings indicate that the SGLT2-selective inhibitor ipragliflozin improves hyperglycemia as well as NASH in type 2 diabetic mice. Therefore, treatment with ipragliflozin monotherapy or coadministered with pioglitazone is expected to be a potential therapeutic option for the treatment of type 2 diabetes with NASH.

Sodium-coupled glucose transport, the SLC5 family, and therapeutically relevant inhibitors: from molecular discovery to clinical application

Sodium glucose transporters (SGLTs) belong to the mammalian solute carrier family SLC5. This family includes 12 different members in human that mediate the transport of sugars, vitamins, amino acids, or smaller organic ions such as choline. The SLC5 family belongs to the sodium symporter family (SSS), which encompasses transporters from all kingdoms of life. It furthermore shares similarity to the structural fold of the APC (amino acid-polyamine-organocation) transporter family. Three decades after the first molecular identification of the intestinal Na⁺-glucose cotransporter SGLT1 by expression cloning, many new discoveries have evolved, from mechanistic analysis to molecular genetics, structural biology, drug discovery, and clinical applications. All of these advances have greatly influenced physiology and medicine. While SGLT1 is essential for fast absorption of glucose and galactose in the intestine, the expression of SGLT2 is largely confined to the early part of the kidney proximal tubules, where it reabsorbs the bulk part of filtered glucose. SGLT2 has been successfully exploited by the pharmaceutical industry to develop effective new drugs for the treatment of diabetic patients. These SGLT2 inhibitors, termed gliflozins, also exhibit favorable nephroprotective effects and likely also cardioprotective effects. In addition, given the recent finding that SGLT2 is also expressed in tumors of pancreas and prostate and in glioblastoma, this opens the door to potential new therapeutic strategies for cancer treatment by specifically targeting SGLT2. Likewise, further discoveries related to the functional association of other SGLTs of the SLC5 family to human pathologies will open the door to potential new therapeutic strategies. We furthermore hope that the herein summarized information about the physiological roles of SGLTs and the therapeutic benefits of the gliflozins will be useful for our readers to better understand the molecular basis of the beneficial effects of these inhibitors, also in the context of the tubuloglomerular feedback (TGF), and the renin-angiotensin system (RAS). The detailed mechanisms underlying the clinical benefits of SGLT2 inhibition by gliflozins still warrant further investigation that may serve as a basis for future drug development.

Empagliflozin suppresses inflammation and protects against acute septic renal injury

BACKGROUND

Sepsis-induced systemic inflammation response syndrome is the leading cause of morbidity and mortality among patients in intensive care units in North America. While sepsis is associated with multiple organ damage, acute renal injury represents a hallmark of sepsis. Since systemic and renal inflammation is known to play a vital role in morbidity and mortality associated with sepsis, identifying a potent anti-inflammatory agent may help minimize morbidity and mortality associated with acute septic kidney injury. Since recent work has suggested that empagliflozin, a renal sodium-glucose cotransporter 2 (SGLT2) inhibitor, may assist in the treatment of inflammatory diseases, our objective was to examine the effect of empagliflozin on acute sepsis-induced renal injury.

METHOD

Mice were treated with three daily doses of empagliflozin or vehicle, with lipopolysaccharide (LPS) administered on the third day, at the same time as the third dose of empagliflozin or vehicle. In another cohort, mice were injected with a single dose of LPS 3 h before a dose of empagliflozin.

RESULTS

Our results show that empagliflozin improves survival in a mouse model of LPS-induced septic shock. We further demonstrate that the beneficial effects of empagliflozin are likely mediated via reducing LPS-induced acute renal injury. Moreover, our data indicate that empagliflozin significantly reduces systemic and renal inflammation to contribute to the improvements observed in an LPS-model of acute septic renal injury.

CONCLUSION

Overall, the findings of this study suggest that empagliflozin could be repurposed to reduce morbidity and mortality in patients with acute septic renal injury.

TRIAL REGISTRATION

Not applicable.

Functional Expression of Sodium-Dependent Glucose Transporter in Amelogenesis

Glucose is an essential source of energy for mammalian cells and is transported into the cells by glucose transporters. There are 2 types of glucose transporters: one is a passive glucose transporter, GLUT (SLC2A), and the other is a sodium-dependent active glucose transporter, SGLT (SLC5A). We previously reported that the expression of GLUTs during tooth development is precisely and spatiotemporally controlled and that the glucose uptake mediated by GLUT1 plays a crucial role in early tooth morphogenesis and tooth size determination. This study aimed to clarify the localization and roles of SGLT1 and SGLT2 in murine ameloblast differentiation by using immunohistochemistry, immunoelectron microscopy, an in vitro tooth organ culture experiment, and in vivo administration of an inhibitor of SGLT1/2, phloridzin. SGLT1, which has high affinity with glucose, was immunolocalized in the early secretory ameloblasts and the ruffle-ended ameloblasts in the maturation stage. However, SGLT2, which has high glucose transport capacity, was observed in the stratum intermedium, papillary layer, and ameloblasts at the maturation stage and colocalized with Na⁺-K⁺-ATPase. The inhibition of SGLT1/2 by phloridzin in the tooth germs induced the disturbance of ameloblast differentiation and enamel matrix formation both in vitro (organ culture) and in vivo (mouse model). The expression of SGLT1 and SGLT2 was significantly upregulated in hypoxic conditions in the ameloblast-lineage cells. These findings suggest that the active glucose uptake mediated by SGLT1 and SGLT2 is strictly regulated and dependent on the intra- and extracellular microenvironments during tooth morphogenesis and that the appropriate passive and active glucose transport is an essential event in amelogenesis.

Therapeutic Effects of SGLT2 Inhibitor Ipragliflozin and Metformin on NASH in Type 2 Diabetic Mice

Background and aim: Sodium-glucose cotransporter (SGLT) 2 is responsible for most of the glucose reabsorption in the kidneys and has been proposed as a novel therapeutic target for the treatment of type 2 diabetes. In recent years, nonalcoholic steatohepatitis (NASH), the pathogenesis of which is strongly associated with insulin resistance, obesity, and type 2 diabetes, has become a considerable healthcare burden worldwide. However, there is currently no established pharmacotherapy for NASH. Here, we investigated the therapeutic effects of the SGLT2 selective inhibitor ipragliflozin alone and in combination with metformin on NASH in high fat and cholesterol diet-fed KK/A^y type 2 diabetic mice.Results: This diabetic model had hyperglycemia, insulin resistance, and obesity, and also exhibited steatosis, inflammation, and fibrosis in the liver, pathological features resembling those in human NASH. Four-week repeated administration of ipragliflozin significantly improved not only hyperglycemia, insulin resistance, and obesity but also hyperlipidemia and NASH-associated symptoms including hepatic steatosis and fibrosis. In addition, ipragliflozin attenuated inflammation and oxidative stress in the liver. Repeated administration of metformin also significantly improved symptoms of type 2 diabetes with NASH to a comparable degree to that by ipragliflozin. In addition, combination treatment with ipragliflozin and metformin additively improved these symptoms.Conclusions: These results demonstrate that the SGLT2 selective inhibitor ipragliflozin improves not only hyperglycemia but also NASH in type 2 diabetic mice, suggesting that treatment with ipragliflozin alone and in combination with metformin may be effective for treating type 2 diabetes with NASH.

Empagliflozin Blunts Worsening Cardiac Dysfunction Associated With Reduced NLRP3 (Nucleotide-Binding Domain-Like Receptor Protein 3) Inflammasome Activation in Heart Failure

BACKGROUND

Although empagliflozin was shown to profoundly reduce cardiovascular events in diabetic patients and blunt the decline in cardiac function in nondiabetic mice with established heart failure (HF), the mechanism of action remains unknown.

METHODS AND RESULTS

We treated 2 rodent models of HF with 10 mg/kg per day empagliflozin and measured activation of the NLRP3 (nucleotide-binding domain-like receptor protein 3) inflammasome in the heart. We show for the first time that beneficial effects of empagliflozin in HF with reduced ejection fraction (HF with reduced ejection fraction [HFrEF]; n=30-34) occur in the absence of changes in circulating ketone bodies, cardiac ketone oxidation, or increased cardiac ATP production. Of note, empagliflozin attenuated activation of the NLRP3 inflammasome and expression of associated markers of sterile inflammation in hearts from mice with HFrEF, implicating reduced cardiac inflammation as a mechanism of empagliflozin that contributes to sustained function in HFrEF in the absence of diabetes mellitus. In addition, we validate that the beneficial cardiac effects of empagliflozin in HF with preserved ejection fraction (HFpEF; n=9-10) are similarly associated with reduced activation of the NLRP3 inflammasome. Lastly, the ability of empagliflozin to reduce inflammation was completely blunted by a calcium (Ca²⁺) ionophore, suggesting that empagliflozin exerts its benefit upon restoring optimal cytoplasmic Ca²⁺ levels in the heart.

CONCLUSIONS

These data provide evidence that the beneficial cardiac effects of empagliflozin are associated with reduced cardiac inflammation via blunting activation of the NLRP3 inflammasome in a Ca²⁺-dependent manner and hence may be beneficial in treating HF even in the absence of diabetes mellitus.

Canagliflozin Increases Postprandial Total Glucagon-Like Peptide 1 Levels in the Absence of α-Glucosidase Inhibitor Therapy in Patients with Type 2 Diabetes: A Single-Arm, Non-randomized, Open-Label Study

INTRODUCTION

To investigate canagliflozin-induced changes in postprandial total glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) levels in patients with type 2 diabetes mellitus (T2DM).

METHODS

Forty-five patients with T2DM who had inadequate glycemic control (glycated hemoglobin ≥ 6.5%) with diet and exercise alone (n = 15, drug naïve) and in combination with either a stable dose of the α-glucosidase inhibitor acarbose (n = 15) or metformin (n = 15) received canagliflozin, a sodium-glucose cotransporter 2 inhibitor, at 100 mg once daily for 12 weeks. The primary endpoint was the change from baseline to week 12 in postprandial glucose and plasma levels of total GLP-1 and GIP during a meal tolerance test (MTT).

RESULTS

Canagliflozin significantly reduced postprandial blood glucose (mean difference - 40.2 mg/mL at 60 min) and increased postprandial total GLP-1 (mean difference 1.8 pg/mL at 60 min) during an MTT. A transient reduction in the postprandial GIP level at only 30 min (mean difference - 80.3 pg/mL) during an MTT was observed. No changes in postprandial GLP-1 or GIP levels were seen after canagliflozin treatment as an add-on to acarbose in patients with T2DM. Acarbose treatment significantly decreased postprandial total GIP levels (P < 0.05) and tended to increase postprandial total GLP-1 levels (P = 0.07) compared to the other two treatments prior to canagliflozin.

CONCLUSION

Canagliflozin 100 mg increased postprandial total GLP-1 levels in the absence of acarbose, suggesting that it may upregulate GLP-1 secretion through delayed glucose absorption in the upper intestine, as with the α-glucosidase inhibitor.

TRIAL REGISTRATION

University Hospital Medical Information Network, UMIN000018345.

FUNDING

Mitsubishi Tanabe Pharma Corporation.

Empaglifozin mitigates NAFLD in high-fat-fed mice by alleviating insulin resistance, lipogenesis and ER stress

AIM

To evaluate the pleiotropic effects of empagliflozin in the liver through lipogenesis, beta-oxidation, and endoplasmic reticulum stress pathways.

METHODS

Male C57Bl/6 mice, 3 months of age, received a control diet (C, 10% lipids, n = 20) or high-fat diet (HF, 50% lipids, n = 20) for 10 weeks, after that, the groups were subdivided to receive empagliflozin, during 5 weeks at a dose of 10 mg/kg/day added to the diets, totalizing four groups: C, C-EMPA, HF, and HF-EMPA. We performed biochemical analyzes, oral glucose tolerance test, homeostasis model assessment of insulin resistance (HOMA-IR), indirect calorimetry, liver stereology, western blotting, RT-qPCR for genes related to beta-oxidation, lipogenesis, and endoplasmic reticulum stress.

RESULTS

After the treatment with empagliflozin, there was a 4% increase in energy expenditure, a 5% reduction in body mass, improvement in glucose tolerance and insulin sensitivity and insulin resistance. The expression of Ppar alpha was greater in the HF-EMPA group with a concomitant reduction in the expression of the lipogenic genes Fas, Srebp1c and Ppar gamma, according to protein expression. In addition, HF-EMPA showed a reduction in the genes related to endoplasmic reticulum stress Chop, Atf4, and Gadd45.

CONCLUSION

Empagliflozin mitigates the development of NAFLD, confirmed through reduced expression of the genes involved in hepatic lipogenesis and genes involved in endoplasmic reticulum stress. Thus, empagliflozin may be an important tool to treat the progression of hepatic steatosis.

SGLT1 inhibition boon or bane for diabetes-associated cardiomyopathy

Chronic hyperglycaemia is a peculiar feature of diabetes mellitus (DM). Sequential metabolic abnormalities accompanying glucotoxicity are some of its implications. Glucotoxicity most likely corresponds to the vascular intricacy and metabolic alterations, such as increased oxidation of free fatty acids and reduced glucose oxidation. More than half of those with diabetes also develop cardiac abnormalities due to unknown causes, posing a major threat to the currently available marketed preparations which are being used for treating these cardiac complications. Even though impairment in cardiac functioning is the principal cause of death in individuals with type 2 diabetes (T2D), reducing plasma glucose levels has little effect on cardiovascular disease (CVD) risk. In vitro and in vivo studies have demonstrated that inhibitors of sodium glucose transporter (SGLT) represent a putative therapeutic intervention for these pathological conditions. Several clinical trials have reported the efficacy of SGLT inhibitors as a novel and potent antidiabetic agent which along with its antihyperglycaemic activity possesses the potential of effectively treating its associated cardiac abnormalities. Thus, hereby, the present review highlights the role of SGLT inhibitors as a successful drug candidate for correcting the shifts in deregulation of cardiac energy substrate metabolism together with its role in treating diabetes-related cardiac perturbations.

Dioscin attenuates oxLDL uptake and the inflammatory reaction of dendritic cells under high glucose conditions by blocking p38 MAPK

Dioscin has been shown to affect the regulation of metabolic diseases, including diabetes; however, the mechanism of action is still unclear. Under high glucose (HG) conditions, the expression of scavenger receptors and the uptake of oxidized low‑density lipoprotein (oxLDL) are upregulated in dendritic cells (DCs), which are critical steps in atherogenesis and inflammation. In this study, the focus was on the impact of dioscin on the function of DCs. Immature DCs were cultured with: 5.5 mM glucose medium (control group); 30 mM glucose medium (HG group); HG + 10 mM dioscin; HG + 20 mM dioscin; HG + 30 mM dioscin; and HG + 40 mM dioscin. For subsequent experiments, 30 mM dioscin was used as the experimental concentration. Dichlorodihydrofluorescein fluorescence was used to measure the intracellular production of reactive oxygen species (ROS) in DCs. The expression levels of the scavenger receptors, including class A scavenger receptors (SR‑A), CD36 and lectin‑like oxidized low‑density lipoprotein receptor‑1 (LOX‑1) were determined via quantitative PCR. The protein expression of p38 mitogen‑activated protein kinase (MAPK) was determined by western blotting. Furthermore, ELISA was used to detect the levels of interleukin (IL)‑6, IL‑10 and IL‑12. Finally, DCs were incubated with diOlistic (Dil)‑labeled oxLDL, and flow cytometry analysis was used to investigate the Dil‑oxLDL‑incorporated fraction. The incubation of DCs with dioscin inhibited the induction of ROS production, in a dose‑dependent manner, under HG conditions. The upregulation of SR‑A, CD36 and LOX‑1 genes was partially abolished by dioscin, which also partially reversed p38 MAPK protein upregulation. Furthermore, increased secretion of IL‑6 and IL‑12, and decreased secretion of IL‑10 in DCs, induced by HG, was also reversed by dioscin. To conclude, dioscin could attenuate the production of ROS, inflammatory cytokine secretion and oxLDL uptake by DCs in HG conditions by preventing the expression of scavenger receptors and p38 MAPK, thus playing a positive role in preventing atherogenesis.

Empagliflozin reduces the levels of CD36 and cardiotoxic lipids while improving autophagy in the hearts of Zucker diabetic fatty rats

The EMPA-REG OUTCOME (Empagliflozin, Cardiovascular Outcome Event Trial in patients with Type 2 Diabetes Mellitus (T2DM)) trial made evident the potentiality of pharmacological sodium-glucose cotransporter 2 (SGLT2) inhibition for treating patients with diabetes and cardiovascular disease. Since the effect of empagliflozin or other SGLT2 inhibitors on the whole cardiac metabolic profile was never analysed before, and with the purpose to contribute to elucidate the benefits at cardiac level of the use of empagliflozin, we explored the effect of the treatment with empagliflozin for six weeks on the cardiac metabolomic profile of Zucker diabetic fatty rats, a model of early stage T2DM, using untargeted metabolomics approach. Empagliflozin reduced significantly the cardiac content of sphingolipids (ceramides and sphingomyelins) and glycerophospholipids (major bioactive contributing factors linking insulin resistance to cardiac damage) and decreased the cardiac content of the fatty acid transporter cluster of differentiation 36 (CD36); induced significant decreases of the cardiac levels of essential glycolysis intermediaries 2,3-bisphosphoglycerate and phosphoenolpyruvate, and regulated the abundance of several amino acids of relevance as tricarboxylic acid suppliers and/or in the metabolic control of the cardiac function as glutamic acid, gamma-aminobutyric acid and sarcosine. Empagliflozin treatment activated the cardioprotective master regulator of cellular energyhomeostasis AMP-activatedproteinkinase (AMPK) and enhanced autophagy at cardiac level, while it decreased significantly the cardiac mRNA levels of the pro-inflammatory cytokines interleukin-6 (IL-6), chemerin, TNF-α and MCP-1, reinforcing the hypothesis of a direct role for empagliflozin in attenuating cardiac inflammation. Our results provide an advancement on the knowledge of the mechanisms linking the therapy with empagliflozin with protective effects on the development of cardiometabolic diseases whose course is associated with remarkable cardiac bioenergetics dysregulation and disarrangement in cardiac metabolome and lipidome.

Comparison of Canagliflozin, Dapagliflozin and Empagliflozin Added to Heart Failure Treatment in Decompensated Heart Failure Patients With Type 2 Diabetes Mellitus

Background: Three sodium-glucose cotransporter-2 inhibitors (SGLT2i), canagliflozin, dapagliflozin and empagliflozin, successfully reduced hospitalization for heart failure (HF) in patients with type 2 diabetes mellitus (T2DM). It remains unclear, however, whether the efficacy of the 3 SGLT2i for HF in T2DM patients is similar.

Methods and Results: Eighty-one T2DM patients hospitalized due to decompensated HF were enrolled. After treatment for HF, one of the 3 SGLT2i was non-randomly used, and clinical parameters for HF and T2DM were followed for 7 days. The attending physician was allowed to adjust the dose of furosemide. No differences were observed between the 3 groups in the increase of glycosuria, or in the decreases of body weight and blood pressure 7 days after SGLT2i (interaction P>0.05). Urine volume was similarly increased on day 1, and returned to the baseline on day 7 in each group. Decrease in B-type natriuretic peptide and increase in plasma renin activity were significant in each group. Plasma aldosterone concentration, however, was significantly increased in the empagliflozin and canagliflozin groups (P<0.01, respectively), but not in the dapagliflozin group. Additionally, plasma noradrenaline was significantly increased in the empagliflozin group (P<0.01), but not in the canagliflozin and dapagliflozin groups.

Conclusions: The neurohumoral responses to the 3 SGLT2i are different under similar volume correction in HF patients with T2DM.

An update of SGLT1 and SGLT2 inhibitors in early phase diabetes-type 2 clinical trials

Introduction: More than 424 million adults have diabetes mellitus (DM). This number is expected to increase to 626 million by 2045. The majority (90-95%) of people with DM has type 2-diabetes (T2DM). The continued prevalence of DM and associated complications has prompted investigators to find new therapies. One of the most recent additions to the anti-diabetic armamentarium are inhibitors of sodium-glucose co-transporters 1 and 2 (SGLT1, SGLT2). Areas covered: The authors review the status of SGLT2 inhibitors for the treatment of T2DM and place an emphasis on those agents in early phase clinical trials. Data and information were retrieved from American Diabetes Association, Diabetes UK, ClinicalTrials.gov, PubMed, and Scopus websites. The keywords used in the search were T2DM, SGLT1, SGLT2, and clinical trials. Expert opinion: The benefits of SGLT inhibitors include reductions in serum glycated hemoglobin (HbA1c), body weight, blood pressure and cardiovascular and renal events. However, SGLT inhibitors increase the risk of genitourinary tract infections, diabetic ketoacidosis, and bone fractures. The development of SGLT inhibitors with fewer side effects and as combination therapies are the key to maximizing the therapeutic effects of this important class of anti-diabetic drug.

Efficacy and Safety of Tofogliflozin on 24-h Glucose Profile Based on Continuous Glucose Monitoring: Crossover Study of Sodium-Glucose Cotransporter 2 Inhibitor

Background: To compare the impact of two sodium-glucose cotransporter 2 (SGLT2) inhibitors, tofogliflozin and ipragliflozin, on hypoglycemia in patients with type 2 diabetes mellitus (T2DM), treated with sulfonylureas. Methods: Thirty patients with T2DM were allocated to treatment with either 20 mg/day tofogliflozin or 50 mg/day ipragliflozin and underwent continuous glucose monitoring (CGM) for 5 days at three times in a crossover manner. Results: The percent time spent at glucose <70 mg/dL per 24 h was 0.48, 2.77, and 0.06%, before treatment with SGLT2 inhibitors and treatment with ipragliflozin and tofogliflozin, respectively (P = 0.1135, difference between SGLT2 inhibitors). The addition of either ipragliflozin or tofogliflozin to sulfonylureas markedly and significantly improved other CGM-derived parameters, including average plasma glucose, standard deviation of glucose, mean postprandial glucose excursion, percent time with glucose >140, >180 mg/dL, and >200 mg/dL, area over the curve <70, area under the curve >140, >180, and >200, and maximum and minimum plasma glucose. However, there were no significant differences in these parameters between the two SGLT2 inhibitors. Conclusions: Based on the CGM, the addition of tofogliflozin to sulfonylureas tended to decrease the percent time spent in hypoglycemia in T2DM patients. The addition of SGLT2 inhibitors to sulfonylureas improved the average glucose level and reduced glucose fluctuations without increasing the time in hypoglycemia.

Efficacy and safety of sodium-glucose cotransporter-2 inhibitors in type 2 diabetes mellitus with inadequate glycemic control on metformin: a meta-analysis

OBJECTIVES

To provide a meta-analysis of the clinical efficacy and safety of sodium glucose co-transporter 2 inhibitors (SGLT2-i), as a combination treatment with metformin in type 2 diabetes mellitus (T2DM) patients with inadequate glycemic control with metformin alone.

MATERIALS AND METHODS

We have searched randomized controlled trials (RCTs) in the database: MEDLINE, Embase and Cochrane Collaborative database. We used mean differences (MD) to assess the efficacy of glycemic and other clinical parameters, and risk ratios (RR) to evaluate the adverse events for safety endpoints. The heterogeneity was evaluated by I2.

RESULTS

Finally 9 studies were included. SGLT2-i plus metformin had higher reduction level in HbA1C [MD = -0.50, 95% CI (-0.62, -0.38), p < 0.00001], FPG [MD = -1.12, 95%CI (-1.38, -0.87), p < 0.00001], body weight [MD = -1.72, 95% CI (-2.05, -1.39), p < 0.00001], SBP [MD = -4.44, 95% CI (-5.45, -3.43), p < 0.00001] and DBP [MD = -1.74, 95% CI (-2.40, -1.07), p < 0.00001] compared with metformin monotherapy. However, SGLT2-i plus metformin group had higher risk of genital infection [RR = 3.98, 95% CI (2.38, 6.67), p < 0.00001]. No significant difference was found in the risk of hypoglycemia, urinary tract infection or volume related adverse events.

CONCLUSIONS

Although the risk of genital infection may increase, SGLT2-i plus metformin may provide an attractive treatment option to those T2DM patients who are unable to achieve glycemic control with metformin alone, based on its effects on glycemic control, reducing body weight and lowering blood pressure.

Effect of sodium-glucose cotransporter 2 inhibitor, empagliflozin, and α-glucosidase inhibitor, voglibose, on hepatic steatosis in an animal model of type 2 diabetes

OBJECTIVE

We investigated the effects of sodium-glucose cotransporter 2 inhibitor, empagliflozin, and α-glucosidase inhibitor, voglibose, on hepatic steatosis in an animal model of type 2 diabetes (T2DM).

METHODS

Empagliflozin (OLETF-EMPA) or voglibose (OLETF-VOG) was administered to Otsuka Long-Evans Tokushima fatty (OLETF) rats once daily for 12 weeks. Control Long-Evans Tokushima Otsuka (LETO) and OLETF (OLETF-C) rats received saline.

RESULTS

Blood glucose levels were significantly suppressed in OLETF-EMPA and OLETF-VOG compared with the OLETF-C group. The liver fat content was significantly higher in the OLETF-C group than in the OLETF-EMPA and OLETF-VOG. Hepatic gene expressions involved in gluconeogenesis (glucose 6-phosphatase [G6Pase], fructose-1,6-bisphosphatase [FBP1], and phosphoenolpyruvate carboxykinase [PEPCK]) and lipogenesis (acetyl-CoA carboxylase [ACC], fatty acid synthase [FAS], and sterol regulatory element-binding transcription factor 1c [SREBP-1c]) were significantly decreased in the OLETF-EMPA group compared with other OLETF groups (OLETF-C and OLETF-VOG). Sirtuin 1 (SIRT1) expression level and SIRT1 activity were markedly reduced in OLETF-C rats; however, its expression increased in the OLETF-EMPA and OLETF-VOG. AMP-activated protein kinase (AMPK) phosphorylation level was remarkably increased by empagliflozin treatment in OLETF rats compared with other OLETF groups. Long-term empagliflozin and voglibose treatment reduced hepatic steatosis with suppression of gluconeogenesis and lipogenesis pathway in OLETF rats.

CONCLUSION

We suggest that this metabolic improvement might be related to SIRT1 and AMPK pathway in T2DM. But empagliflozin is thought to have more advantage to prevent hepatic steatosis than voglibose in T2DM.

Canagliflozin Inhibits Human Endothelial Cell Proliferation and Tube Formation

Recent clinical trials revealed that sodium-glucose co-transporter 2 (SGLT2) inhibitors significantly reduce cardiovascular events in type 2 diabetic patients, however, canagliflozin increased limb amputations, an effect not seen with other SGLT2 inhibitors. Since endothelial cell (EC) dysfunction promotes diabetes-associated vascular disease and limb ischemia, we hypothesized that canagliflozin, but not other SGLT2 inhibitors, impairs EC proliferation, migration, and angiogenesis. Treatment of human umbilical vein ECs (HUVECs) with clinically relevant concentrations of canagliflozin, but not empagliflozin or dapagliflozin, inhibited cell proliferation. In particular, 10 μM canagliflozin reduced EC proliferation by approximately 45%. The inhibition of EC growth by canagliflozin occurred in the absence of cell death and was associated with diminished DNA synthesis, cell cycle arrest, and a striking decrease in cyclin A expression. Restoration of cyclin A expression via adenoviral-mediated gene transfer partially rescued the proliferative response of HUVECs treated with canagliflozin. A high concentration of canagliflozin (50 μM) modestly inhibited HUVEC migration by 20%, but markedly attenuated their tube formation by 65% and EC sprouting from mouse aortas by 80%. A moderate 20% reduction in HUVEC migration was also observed with a high concentration of empagliflozin (50 μM), while neither empagliflozin nor dapagliflozin affected tube formation by HUVECs. The present study identified canagliflozin as a robust inhibitor of human EC proliferation and tube formation. The anti-proliferative action of canagliflozin occurs in the absence of cell death and is due, in part, to the blockade of cyclin A expression. Notably, these actions are not seen with empagliflozin or dapagliflozin. The ability of canagliflozin to exert these pleiotropic effects on ECs may contribute to the clinical actions of this drug.

Ipragliflozin Add-on Therapy to a GLP-1 Receptor Agonist in Japanese Patients with Type 2 Diabetes (AGATE): A 52-Week Open-Label Study

INTRODUCTION

Few data are available regarding ipragliflozin treatment in combination with glucagon-like peptide-1 (GLP-1) receptor agonists. The aim of this study was to evaluate the efficacy and safety of ipragliflozin in combination with GLP-1 receptor agonists in Japanese patients with inadequately controlled type 2 diabetes mellitus (T2DM).

METHODS

This multicenter study (consisting of three periods: a 4-week washout period, a 6-week observation period, and a 52-week open-label treatment period) included patients aged ≥ 20 years who received a stable dose/regimen of a GLP-1 receptor agonist either solely or in combination therapy with a sulfonylurea for ≥ 6 weeks, with glycosylated hemoglobin (HbA1c) of ≥ 7.5% and a fasting plasma glucose (FPG) of ≥ 126 mg/dL. Ipragliflozin treatment was given at a fixed dose of 50 mg/day for 20 weeks, followed by 50 or 100 mg/day for 32 weeks. Changes from baseline in glycemic control and other parameters were examined; safety was also assessed.

RESULTS

The mean changes in HbA1c and body weight from baseline to end of treatment were - 0.92% and - 2.69 kg, respectively, in all ipragliflozin-treated patients (n = 103). Overall, sustained reductions from baseline were observed for HbA1c, FPG, self-monitored blood glucose, and body weight during the 52-week treatment. The dose increase of ipragliflozin to 100 mg/day resulted in better glycemic control and weight reduction for patients in whom the 50-mg dose was insufficient. Overall, 46.6% (48/103) of patients experienced drug-related adverse events. The most common drug-related treatment-emergent adverse events were pollakiuria (9.7%), hypoglycemia (8.7%), constipation (6.8%), and thirst (5.8%).

CONCLUSION

Combined therapy with ipragliflozin and GLP-1 receptor agonists/sulfonylureas was significantly efficacious in reducing glycemic parameters in patients with T2DM with inadequate glycemic control, and no major safety concerns were identified. The results from this study suggest that ipragliflozin can be recommended as a well-tolerated and effective add-on therapy to a GLP-1 receptor agonist for the treatment of T2DM.

TRIAL REGISTRATION

ClinicalTrials.gov (identifier: NCT02291874).

FUNDING

Astellas Pharma Inc., Tokyo, Japan.

Sodium-glucose cotransporter 2 (SGLT-2) inhibitors: a new antidiabetic drug class

Diabetes mellitus is a chronic, complex and multifactorial disease associated characteristically with hyperglycemia. One of the most recently approved antidiabetic drug classes for clinical use are sodium-glucose cotransporter type 2 (SGLT-2) inhibitors. SGLT-2 is a protein expressed in the kidneys, responsible for glucose reabsorption from the glomerular filtrate to the plasma. It is known, nowadays, that diabetic patients show an increased glucose renal reabsorption capacity, caused by the overexpression of the SGLT-2 transporter, thus contributing to hyperglycemia. From establishing this correlation, the SGLT-2 transporter started to be considered as a therapeutic target of interest, culminating in the approval of the first antidiabetic SGLT-2 inhibitor, dapagliflozin (Forxiga® or Farxiga®, Bristol-Myers Squibb & AstraZeneca), in 2012 in Europe. On the other hand, canagliflozin (Invokana®, Janssen Pharmaceutical) was the first drug in this class to be approved by the FDA, the U.S. Food and Drug Administration, in 2013. This review concerns the discovery and development of the first representatives of this class of antidiabetic drugs, and the description of new optimized analogues that are currently in the clinical and preclinical stages of development.

Distinct Glucose-Lowering Mechanisms of Ipragliflozin Depending on Body Weight Changes

BACKGROUND

Sodium-glucose co-transporter 2 inhibitors have been shown to reduce body weight. However, little is known about whether a reduction in body weight affects glycemic and non-glycemic parameters.

OBJECTIVES

The aim of this study was to investigate the link between the changes in body weight and those in metabolic parameters in drug-naïve subjects with type 2 diabetes mellitus (T2DM) receiving ipragliflozin monotherapy.

METHODS

Subjects received ipragliflozin monotherapy 25-50 mg/day for 3 months (n = 33). They were then divided into two groups: group L ('lost'; n = 17) comprised patients who lost weight (change [Δ] in body mass index [BMI] ≤ -0.75, p < 0.00001), and group N ('neutral'; n = 16) comprised patients who did not lose weight (ΔBMI > -0.75, not significant [NS]).

RESULTS

In these two groups, similar reductions were observed in glycated hemoglobin (HbA_1c) levels (group L: 9.76-8.02%, p < 0.00001; group N: 10.07-8.36%, p < 0.0005). Homeostasis model assessment (HOMA)-B levels increased in both groups, with inter-group differences (p < 0.05; +38.91 vs. +96.83% in group L and N, respectively). However, some parameters showed distinct regulatory patterns. For instance, in group L, reductions were observed in HOMA-R (-20.18%, p < 0.04) and uric acid (UA; -8.91%, p < 0.02) levels. Correlations were seen between the change in HOMA-R and those in fasting blood glucose (FBG) levels (R = 0.557, p < 0.02). Non-significant increases in free fatty acid (FFA) levels and decreases in non-high-density lipoprotein cholesterol (non-HDL-C) or low-density lipoprotein cholesterol (LDL-C) levels were also noted. In group N, reductions in FFA levels (-17.07%, p < 0.05) were observed, and negative correlations were seen between ΔHOMA-B and ΔFBG (R = -0.4781, p < 0.05) and between Δ FFA and Δ HOMA-B levels (R = -0.4305, p < 0.05). Non-significant increases in non-HDL-C and LDL-C levels were also noted. Inter-group differences existed between group L and group N in the changes in non-HDL-C and LDL-C levels (both p < 0.05).

CONCLUSIONS

These results indicate that ipragliflozin may possess distinct dual glucose-lowering mechanisms depending on body weight changes. Degrees of insulin resistance decrease in subjects who lose weight. Conversely, ipragliflozin reduces lipotoxicity (FFA levels), thereby activating beta-cell function, in subjects who do not lose weight. Similar glycemic efficacies were observed in both cases. In patients who lost weight, ipragliflozin was associated with improvements in the levels of metabolic parameters related to cardiovascular risk factors, including UA and atherogenic lipid levels (non-HDL-C and LDL-C) compared with those who did not lose weight.

Sodium-glucose transporter as a novel therapeutic target in disease

Glucose is the primary energy fuel of life. A glucose transporter, the sodium-glucose transporter (SGLT), is receiving attention as a novel therapeutic target in disease. This review summarizes the physiological role of SGLT in cerebral ischemia, cancer, cardiac disease, and intestinal ischemia, which has encouraged analysis of SGLT function. In cerebral ischemia and cardiomyopathy, SGLT-1 is involved in worsening of the injury. In addition, SGLT-1 promotes the development of cancer. On the other hand, SGLT-1 has a protective effect against cardiac and intestinal ischemia. Interestingly, SGLT-1 expression levels are increased in some diseased tissue, such as in cerebral ischemia and cancer. This suggests that SGLT-1 may have an important role in many diseases. This review discusses the potential of SGLT as a target for novel therapeutic agents.

Antidiabetic and antiobesity effects of SGLT2 inhibitor ipragliflozin in type 2 diabetic mice fed sugar solution

Obesity due to excessive calorie intake is a known aggravating factor contributing to the development and progression of type 2 diabetes. Recently, excessive intake of sugar-sweetened beverages has presented challenges in stemming the tide of obesity. Here, we investigated the possible effects of sugar solution intake on the antidiabetic effects of sodium-glucose cotransporter 2 (SGLT2) inhibitor ipragliflozin in type 2 diabetic mice that were fed ordinary drinking water, water + glucose solution, or water + sucrose solution. Under all feeding conditions, all mice exhibited type 2 diabetic symptoms, including hyperglycemia, hyperinsulinemia, and obesity; ipragliflozin subsequently improved these symptoms through increases in urinary glucose excretion. Effective dose of and response to ipragliflozin for diabetes improvement did not significantly differ by feeding condition. Further, under all feeding conditions, ipragliflozin administration resulted in significantly increased intake of both water and sugar solutions in association with increased urine volume resulting from increased urinary glucose excretion. In sugar solution-fed diabetic mice, ipragliflozin administration tended to slightly increase the proportion of sugar solution intake in total drinking volume, although not significantly so. In addition, ipragliflozin significantly decreased calorie balance, as calculated using calorie intake from food and sugar solution and calorie excretion via urinary glucose excretion. Our observation that the antidiabetic and antiobesity effects of the SGLT2 inhibitor ipragliflozin were not greatly affected by sugar solution intake in type 2 diabetic mice suggests that, in a clinical setting, ipragliflozin will remain an effective treatment for type 2 diabetic patients with excessive intake of carbohydrates.

Protein tyrosine phosphatase 1B deficiency in podocytes mitigates hyperglycemia-induced renal injury

OBJECTIVE

Diabetic nephropathy is one of the most devastating complications of diabetes, and growing evidence implicates podocyte dysfunction in disease pathogenesis. The objective of this study was to investigate the contribution of protein tyrosine phosphatase 1B (PTP1B) in podocytes to hyperglycemia-induced renal injury.

METHODS

To determine the in vivo function of PTP1B in podocytes we generated mice with podocyte-specific PTP1B disruption (hereafter termed pod-PTP1B KO). Kidney functions were determined in control and pod-PTP1B KO mice under normoglycemia and high-fat diet (HFD)- and streptozotocin (STZ)-induced hyperglycemia.

RESULTS

PTP1B expression increased in murine kidneys following HFD and STZ challenges. Under normoglycemia control and pod-PTP1B KO mice exhibited comparable renal functions. However, podocyte PTP1B disruption attenuated hyperglycemia-induced albuminuria and renal injury and preserved glucose control. Also, podocyte PTP1B disruption was accompanied with improved renal insulin signaling and enhanced autophagy with decreased inflammation and fibrosis. Moreover, the beneficial effects of podocyte PTP1B disruption in vivo were recapitulated in E11 murine podocytes with lentiviral-mediated PTP1B knockdown. Reconstitution of PTP1B in knockdown podocytes reversed the enhanced insulin signaling and autophagy suggesting that they were likely a consequence of PTP1B deficiency. Further, pharmacological attenuation of autophagy in PTP1B knockdown podocytes mitigated the protective effects of PTP1B deficiency.

CONCLUSIONS

These findings demonstrate that podocyte PTP1B deficiency attenuates hyperglycemia-induced renal damage and suggest that PTP1B may present a therapeutic target in renal injury.

Effect of canagliflozin on circulating active GLP-1 levels in patients with type 2 diabetes: a randomized trial

Canagliflozin has a robust inhibitory effect on sodium glucose transporter (SGLT)-2 and a mild inhibitory effect on SGLT1. The main purpose of this study was to investigate the effect of canagliflozin on circulating active glucagon-like peptide 1 (GLP-1) levels in patients with type 2 diabetes. Patients were randomly divided into a control group (n =15) and a canagliflozin-treated group (n =15). After hospitalization, the canagliflozin-treated group took 100 mg/day canagliflozin for the entire study, and after 3 days both groups took 20 mg/day teneligliptin for an additional 3 days. In a meal test, canagliflozin significantly decreased the area under curve (AUC) (0-120 min) for plasma glucose (PG) after 3 days when compared with that at baseline, and addition of teneligliptin to the canagliflozin-treated group further decreased it. A significant decrease in the AUC (0-120 min) for serum insulin by canagliflozin was obtained, but the addition of teneligliptin elevated the AUC, and thus abolished the significant difference from baseline. A significant increase in the AUC (0-120 min) of plasma active GLP-1 by canagliflozin-treatment compared with that at baseline was observed, and the addition of teneligliptin resulted in a further increase. However, canagliflozin-treatment did not change the AUC (0-120 min) of plasma active glucose-dependent insulinotropic peptide (GIP). In conclusions, canagliflozin-administration before meals decreased PG and serum insulin, and increased plasma active GLP-1 levels in patients with type 2 diabetes. Canagliflozin did not greatly influence plasma active GIP levels.

Metabolic Recovery of the Failing Heart: Emerging Therapeutic Options

Heart failure has mortality rates that parallel those of breast cancer. Current management strategies include neurohormonal blockade, rate control measures, natriuretic peptide preservation, implantation of mechanical assist devices, and heart transplantation. Despite these strategies, however, the failing myocardium remains energy depleted. New strategies to promote metabolic recovery are being developed to potentially augment current treatment guidelines. For example, an unexpected finding of our own studies showed that mechanical unloading with assist devices in advanced-stage heart failure restored metabolic flux. Unfortunately, at that point it is too late for myocardial recovery. Traditional metabolic therapies addressing hyperglycemia have had limited long-term outcome benefit. Now, new therapeutic options are emerging based on increased understanding of the molecular mechanisms underlying energy depletion. Metabolic cardiac imaging combined with laboratory diagnostics could guide the design of individual therapeutic strategies. To date, agents that show benefit in select individuals include mimetics that stimulate glucagon-like peptide-1, inhibitors of sodium-glucose cotransporter receptors, drugs that limit fatty acid oxidation, and hormonal therapy in select individuals. This review will summarize mechanisms and investigations related to these metabolic approaches to heart failure.

Diabetes and the Small Intestine

OPINION STATEMENT

Diabetes mellitus (DM) and its associated complications are becoming increasingly prevalent. Gastrointestinal symptoms associated with diabetes is known as diabetic enteropathy (DE) and may manifest as either diarrhea, fecal incontinence, constipation, dyspepsia, nausea, and vomiting or a combination of symptoms. The long-held belief that vagal autonomic neuropathy is the primary cause of DE has recently been challenged by newer theories of disease development. Specifically, hyperglycemia and the resulting oxidative stress on neural networks, including the nitrergic neurons and interstitial cells of Cajal (ICC), are now believed to play a central role in the development of DE. DE occurs in the majority of patients with diabetes; however, tools for early diagnosis and targeted therapy to counter the detrimental and potentially irreversible effects on the small bowel are lacking. Delay in diagnosis is further compounded by the fact that DE symptoms overlap with those of gastroparesis or can be confused with side effects from diabetes medications. Still, early recognition of the presence of DE is essential to mitigating symptoms and preventing further progression of complications including dysmotility and malabsorption. Current diagnostic modalities include manometry, wireless motility capsule (SmartPill™), and scintigraphy; however, these are not regularly utilized in clinical practice due to limited availability. Several medications are available for symptom relief in DE patients including rifaximin for small intestinal bacterial overgrowth (SIBO) and somatostatin analogues for diarrhea. While rodent models on stem cell therapy and alteration of the microbiome are promising, there is still a great need for further research on the pathologic underpinnings and development of novel treatment modalities for DE.

Effectiveness of Ipragliflozin for Reducing Hemoglobin A1c in Patients With a Shorter Type 2 Diabetes Duration: Interim Report of the ASSIGN-K Study

Background

Ipragliflozin is a selective sodium glucose co-transporter 2 inhibitor. The ASSIGN-K study is investigating the efficacy and safety of ipragliflozin for type 2 diabetes mellitus (T2DM) in the real-world clinical setting.

Methods

Japanese T2DM patients with inadequate glycemic control despite diet and exercise with/without pharmacotherapy were enrolled in an investigator-driven, multicenter, prospective, observational study examining the efficacy and safety of ipragliflozin treatment (50 mg/day for 52 weeks). We performed interim analysis after 24 weeks.

Results

In 367 patients completing 24-week ipragliflozin therapy, hemoglobin A1c (HbA1c) decreased significantly from 8.07% at baseline to 7.26% in week 24 (P < 0.001). The change in HbA1c from treatment initiation to week 24 was -0.88% in patients < 65 years old versus -0.55% in those ≥ 65 years and -0.92% in men versus -0.70% in women (all P < 0.001). When baseline HbA1c was < 7%, 7% to < 8%, and ≥ 8%, the change was -0.18%, -0.45%, and -1.48%, respectively (P = 0.5352, P < 0.001, and P < 0.001, respectively). When baseline body mass index (BMI) was < 25, 25 to < 30, and ≥ 30, the change was -1.05%, -0.65%, and -0.87%, respectively (all P < 0.001). Multiple regression analysis showed that HbA1c decreased more in patients with a higher baseline HbA1c or shorter duration of diabetes. An HbA1c < 7% was achieved in 33.3% of the patients, and their baseline HbA1c was significantly lower than that of patients failing to achieve it (P < 0.001). Adverse events (AEs) occurred in 106/451 patients (23.5%), including 29.1% of patients aged 65 or older. Common AEs were vulvovaginal candidiasis (3.1%) and genital pruritus (1.8%). Serious AEs included urinary tract infection, unstable angina, and ketosis, which occurred in patients who did not suspend medication during acute illness.

Conclusions

Ipragliflozin significantly improved HbA1c in T2DM patients with inadequate glycemic control. Improvement in HbA1c was significant irrespective of age, sex, baseline HbA1c, or BMI, but efficacy was greater with a higher baseline HbA1c and shorter duration of diabetes. For safe continuation of treatment, patients should be advised to suspend medication during acute illness.

Effect of Sodium Glucose Cotransporter 2 Inhibitors With Low SGLT2/SGLT1 Selectivity on Circulating Glucagon-Like Peptide 1 Levels in Type 2 Diabetes Mellitus

Sodium glucose cotransporter 2 (SGLT2) inhibitors are a new class of antidiabetic drugs that improve glycemic control by inhibiting reabsorption of glucose filtered through the renal glomerulus. Use of drugs in this class has increased because of their effect of decreasing body weight and a low risk for hypoglycemia, in addition to a relatively strong glucose-lowering effect. SGLT2 inhibitors such as canagliflozin and sotagliflozin (a SGLT1/SGLT2 dual inhibitor) also have a mild or moderate intestinal and renal SGLT1 inhibitory effect because of their relatively weak selectivity for SGLT2 over SGLT1. Recent evidence shows that these SGLT2 inhibitors with low SGLT2/SGLT1 selectivity elevate the level of circulating glucagon like peptide-1 (GLP-1), an incretin hormone that promotes insulin secretion in pancreatic β cells. This effect probably occurs partly via inhibition of intestinal SGLT1, and the elevation of active GLP-1 levels is especially apparent when these drugs are co-administered with dipeptidyl peptidase 4 (DPP4) inhibitors. These findings suggest that a combination of canagliflozin or sotagliflozin and a DPP4 inhibitor can provide a beneficial effect associated with elevation of circulating active GLP-1 and may serve as a treatment for patients with type 2 diabetes.

Long-term efficacy and safety of sodium-glucose cotransporter-2 inhibitors as add-on to metformin treatment in the management of type 2 diabetes mellitus: A meta-analysis

BACKGROUND

Drug intensification is often required for patients with type 2 diabetes mellitus on stable metformin therapy. Among the potential candidates for a combination therapy, sodium-glucose transporter-2 (SGLT2) inhibitors have shown promising outcomes. This meta-analysis was performed to compare the efficacy and safety of SGLT2 inhibitors with non-SGLT2 combinations as add-on treatment to metformin.

METHODS

Literature search was carried out in multiple electronic databases for the acquisition of relevant randomized controlled trials (RCTs) by following a priori eligibility criteria. After the assessment of quality of the included RCTs, meta-analyses of mean differences or odds ratios (OR) were performed to achieve overall effect sizes of the changes from baseline in selected efficacy and safety endpoints reported in the individual studies. Between-studies heterogeneity was estimated with between-studies statistical heterogeneity (I) index.

RESULTS

Six RCTs fulfilled the eligibility criteria. SGLT2 inhibitors as add-on to metformin treatment reduced % HbA1c significantly more than non-SGLT2 combinations after 52 weeks (P = .002) as well as after 104 weeks (P < .00001). Among other endpoints, SGLT2 inhibitors also reduced fasting plasma glucose levels, body weight, systolic, and diastolic blood pressures after 52 weeks and 104 weeks significantly (P < .00001) more than non-SGLT2 combinations. Incidence of hypoglycemia was significantly lower (P = .02) but incidence of suspected or confirmed genital tract infections was significantly higher (P < .00001) in SGLT2 inhibitors treated in comparison with non-SGLT2 combinations.

CONCLUSION

As add-on to metformin treatment, SGLT2 inhibitors are found significantly more efficacious than non-SGLT2 inhibitor combinations in the management of type 2 diabetes mellitus, although, SGLT2 inhibitor therapy is associated with significantly higher incidence of suspected or confirmed genital tract infections.