LX4211 increases serum glucagon-like peptide 1 and peptide YY levels by reducing sodium/glucose cotransporter 1 (SGLT1)-mediated absorption of intestinal glucose

The U.S. FDA approved cardiovascular drugs from 2011 to 2023: A medicinal chemistry perspective

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality worldwide. A total of 28 new molecular entities (NMEs) were approved by the U.S. Food and Drug Administration (FDA) for the treatment of cardiovascular diseases from 2011 to 2023. Approximately 25 % of the medications were sanctioned for the management of diverse vascular disorders. The other major therapeutic areas of focus included antilipemic agents (15 %), blood pressure disease (11 %), heart failure, hyperkalemia, and cardiomyopathy (7-8% each). Among all the approved drugs, there are a total of 22 new chemical entities (NCEs), including inhibitors, agonists, polymers, and inorganic compounds. In addition to NCEs, 6 biological agents (BLAs), including monoclonal antibodies, small interfering RNAs (siRNAs), and antisense oligonucleotides, have also obtained approval for the treatment of cardiovascular diseases. From this perspective, approved NCEs are itemized and discussed based on their disease, targets, chemical classes, major drug metabolites, and biochemical and pharmacological properties. Systematic analysis has been conducted to examine the binding modes of these approved drugs with their targets using cocrystal structure information or docking studies to provide valuable insights for designing next-generation agents. Furthermore, the synthetic approaches employed in the creation of these drug molecules have been emphasized, aiming to inspire the development of novel, efficient, and applicable synthetic methodologies. Generally, the primary objective of this review is to provide a comprehensive examination of the clinical applications, pharmacology, binding modes, and synthetic methodologies employed in small-molecule drugs approved for treating CVD. This will facilitate the development of more potent and innovative therapeutics for effectively managing cardiovascular diseases.

Synthetic approaches and clinical application of small-molecule inhibitors of sodium-dependent glucose transporters 2 for the treatment of type 2 diabetes mellitus

Sodium-dependent glucose transporters 2 (SGLT2) inhibitors are a class of small-molecule drugs that have gained significant attention in recent years for their potential clinical applications in the treatment of type 2 diabetes mellitus (T2DM). These inhibitors function by obstructing the kidneys' ability to reabsorb glucose, resulting in a rise in the excretion of glucose in urine (UGE) and subsequently lowering blood glucose levels. Several SGLT2 inhibitors, such as Dapagliflozin, Canagliflozin, and Empagliflozin, have been approved by regulatory authorities and are currently available for clinical use. These inhibitors have shown notable enhancements in managing blood sugar levels, reducing body weight, and lowering blood pressure in individuals with T2DM. Additionally, they have exhibited potential advantages in decreasing the likelihood of cardiovascular incidents and renal complications among this group of patients. This review article focuses on the synthesis and clinical application of small-molecule SGLT2 inhibitors, which have provided a new therapeutic approach for the management of T2DM.

Synthesis and clinical application of new drugs approved by FDA in 2023

In 2023, the U.S. Food and Drug Administration (FDA) granted approval to a total of 55 new drugs, comprising 29 new chemical entities (NCEs) and 25 new biological entities (NBEs). These drugs primarily focus on oncology, the central nervous system, anti-infection, hematology, cardiovascular, ophthalmology, immunomodulatory and other therapeutic areas. Out of the 55 drugs, 33 (60 %) underwent an accelerated review process and received approval, while 25 (45 %) were specifically approved for the treatment of rare diseases. The purpose of this review is to provide an overview of the clinical uses and production techniques of 29 newly FDA-approved NCEs in 2023. Our intention is to offer a comprehensive understanding of the synthetic approaches employed in the creation of these drug molecules, with the aim of inspiring the development of novel, efficient, and applicable synthetic methodologies.

Transport and inhibition mechanism of the human SGLT2-MAP17 glucose transporter

Sodium-glucose cotransporter 2 (SGLT2) is imporant in glucose reabsorption. SGLT2 inhibitors suppress renal glucose reabsorption, therefore reducing blood glucose levels in patients with type 2 diabetes. We and others have developed several SGLT2 inhibitors starting from phlorizin, a natural product. Using cryo-electron microscopy, we present the structures of human (h)SGLT2-MAP17 complexed with five natural or synthetic inhibitors. The four synthetic inhibitors (including canagliflozin) bind the transporter in the outward conformations, while phlorizin binds it in the inward conformation. The phlorizin-hSGLT2 interaction exhibits biphasic kinetics, suggesting that phlorizin alternately binds to the extracellular and intracellular sides. The Na+-bound outward-facing and unbound inward-open structures of hSGLT2-MAP17 suggest that the MAP17-associated bundle domain functions as a scaffold, with the hash domain rotating around the Na+-binding site. Thus, Na+ binding stabilizes the outward-facing conformation, and its release promotes state transition to inward-open conformation, exhibiting a role of Na+ in symport mechanism. These results provide structural evidence for the Na+-coupled alternating-access mechanism proposed for the transporter family.

A randomized double-blind phase Ib clinical trial of SY-009 in patients with type 2 diabetes mellitus

INTRODUCTION

SY-009 produces a hypoglycemic effect via inhibiting sodium/glucose cotransporter 1 (SGLT1) in type 2 diabetes mellitus (T2DM) patients. This randomized, double-blind, placebo-controlled, and multiple-dose escalation clinical trial aimed to evaluate the pharmacokinetic and pharmacodynamical characteristics as well as the safety and tolerability of SY-009 in T2DM patients.

METHOD

Fifty T2DM patients were randomized into experimental and placebo groups, and hospitalized for 9 days managed with a unified diet and rest management. Subjects were given SY-009 or placebo from day 1 to day 7 at different frequencies and dosages. Single dose cohort was defined as the first dose on day 1 and multiple dose cohort included all the dose from day 1 to 7. Blood samples were collected for pharmacokinetic analysis. Mixed meal tolerance tests were performed. Blood samples were collected to determine glucose, C-peptide, insulin, glucagon-like peptide-1 (GLP-1), and gastric inhibitory polypeptide (GIP).

RESULTS

PK parameters were not obtained because blood SY-009 concentrations were below the limit of quantitation in all subjects. SY-009 decreased the postprandial glucose. Blood glucose was controlled within 4 hours after taking the drug. Short-term administration of SY-009 (7 days) had no significant effects on fasting glucose but reduced the secretion of C-peptide, insulin, and GIP and increased GLP-1 secretion. The most common adverse event was gastrointestinal disorder manifesting abdominal pain, diarrhea, and bloating.

CONCLUSION

Plasma exposure of SY-009 and its metabolites was fairly low in T2DM patients at doses of 1.0-4.0 mg. SY-009 reduced postprandial glucose, C-peptide, and insulin levels, showing relative safety and tolerability in the dose range of 1.0-4.0 mg.

TRIALS REGISTRATION

ClinicalTrials.gov Identifier: NCT04345107.

Comparison of SGLT1, SGLT2, and Dual Inhibitor biological activity in treating Type 2 Diabetes Mellitus

Diabetes Mellitus Type 2 (T2D) is an emerging health burden in the USand worldwide, impacting approximately 15% of Americans. Current front-line therapeutics for T2D patients include sulfonylureas that act to reduce A1C and/or fasting blood glucose levels, or Metformin that antagonizes the action of glucagon to reduce hepatic glucose production. Next generation glucomodulatory therapeutics target members of the high-affinity glucose transporter Sodium-Glucose-Linked-Transporter (SGLT) family. SGLT1 is primarily expressed in intestinal epithelium, whose inhibition reduces dietary glucose uptake, whilst SGLT2 is highly expressed in kidney - regulating glucose reabsorption. A number of SGLT2 inhibitors are FDA approved whilst SGLT1 and dual SGLT1 & 2 inhibitor are currently in clinical trials. Here, we discuss and compare SGLT2, SGLT1, and dual inhibitors' biochemical mechanism and physiological effects.

Applications of Enteroendocrine Cells (EECs) Hormone: Applicability on Feed Intake and Nutrient Absorption in Chickens

This review focuses on the role of hormones derived from enteroendocrine cells (EECs) on appetite and nutrient absorption in chickens. In response to nutrient intake, EECs release hormones that act on many organs and body systems, including the brain, gallbladder, and pancreas. Gut hormones released from EECs play a critical role in the regulation of feed intake and the absorption of nutrients such as glucose, protein, and fat following feed ingestion. We could hypothesize that EECs are essential for the regulation of appetite and nutrient absorption because the malfunction of EECs causes severe diarrhea and digestion problems. The importance of EEC hormones has been recognized, and many studies have been carried out to elucidate their mechanisms for many years in other species. However, there is a lack of research on the regulation of appetite and nutrient absorption by EEC hormones in chickens. This review suggests the potential significance of EEC hormones on growth and health in chickens under stress conditions induced by diseases and high temperature, etc., by providing in-depth knowledge of EEC hormones and mechanisms on how these hormones regulate appetite and nutrient absorption in other species.

Mechanistic evaluation of the inhibitory effect of four SGLT-2 inhibitors on SGLT 1 and SGLT 2 using physiologically based pharmacokinetic (PBPK) modeling approaches

Sodium-glucose co-transporter type 2 (SGLT 2, gliflozins) inhibitors are potent orally active drugs approved for managing type 2 diabetes. SGLT 2 inhibitors exert a glucose-lowering effect by suppressing sodium-glucose co-transporters 1 and 2 in the intestinal and kidney proximal tubules. In this study, we developed a physiologically based pharmacokinetic (PBPK) model and simulated the concentrations of ertugliflozin, empagliflozin, henagliflozin, and sotagliflozin in target tissues. We used the perfusion-limited model to illustrate the disposition of SGLT 2 inhibitors in vivo. The modeling parameters were obtained from the references. Simulated steady-state plasma concentration-time curves of the ertugliflozin, empagliflozin, henagliflozin, and sotagliflozin are similar to the clinically observed curves. The 90% prediction interval of simulated excretion of drugs in urine captured the observed data well. Furthermore, all corresponding model-predicted pharmacokinetic parameters fell within a 2-fold prediction error. At the approved doses, we estimated the effective concentrations in intestinal and kidney proximal tubules and calculated the inhibition ratio of SGLT transporters to differentiate the relative inhibition capacities of SGLT1 and 2 in each gliflozin. According to simulation results, four SGLT 2 inhibitors can nearly completely inhibit SGLT 2 transporter at the approved dosages. Sotagliflozin exhibited the highest inhibition activity on SGLT1, followed by ertugliflozin, empagliflozin, and henagliflozin, which showed a lower SGLT 1 inhibitory effect. The PBPK model successfully simulates the specific target tissue concentration that cannot be measured directly and quantifies the relative contribution toward SGLT 1 and 2 for each gliflozin.

Metabolic effects of the dual SGLT 1/2 inhibitor sotagliflozin on blood pressure and body weight reduction in people with diabetes: An updated meta-analysis of randomized controlled trials

AIM

To update the meta-analysis of the metabolic effects of a dual sodium-glucose co-transpoter-1/2 inhibitor, sotagliflozin, on blood pressure (BP) and body weight in people with diabetes.

METHODS

An electronic search up to March 8, 2022, were conducted to determine eligible randomized-controlled trials of sotagliflozin-reporting BP and weight change outcomes in adults with diabetes.

RESULTS

16 trials were included, with a combined cohort of 19,140 patients. Compared with placebo, sotagliflozin had a mean systolic blood pressure reduction (weighted mean differences (WMDs) -2.60 mmHg, 95 % CI: -2.90 to -2.30), mean diastolic blood pressure reduction (WMD -0.96 mmHg, 95 % CI: -1.17 to -0.75), and mean weight loss (WMD -1.88 kg, 95 % CI: -2.16 to -1.59). Metabolic effects on BP-lowering and weight loss were observed across diabetes status, duration of follow-up, and chronic kidney disease comorbidity. Meanwhile sotagliflozin presented significant effects on people with type 1 diabetes and showed a dose-response relationship for BP-lowering and weight loss.

CONCLUSION

This meta-analysis enriches the evidence on the metabolic benefits, including BP-lowering and weight loss, of sotagliflozin, and provide a reasonable therapeutic option for managing diabetes with metabolic syndrome. Further studies will be required to elucidate its long-term effects and role in metabolic syndrome management.

PROSPERO REGISTRATION NUMBER

CRD42022323945.

Colonic Delivery of Nutrients for Sustained and Prolonged Release of Gut Peptides: A Novel Strategy for Appetite Management

Obesity is one of the major global threats to human health and risk factors for cardiometabolic diseases and certain cancers. Glucagon-like peptide-1 (GLP-1) plays a major role in appetite and glucose homeostasis and recently the USFDA approved GLP-1 agonists for the treatment of obesity and type 2 diabetes. GLP-1 is secreted from enteroendocrine L-cells in the distal part of the gastrointestinal (GI) tract in response to nutrient ingestion. Endogenously released GLP-1 has a very short half-life of <2 min and most of the nutrients are absorbed before reaching the distal GI tract and colon, which hinders the use of nutritional compounds for appetite regulation. The review article focuses on nutrients that endogenously stimulate GLP-1 and peptide YY (PYY) secretion via their receptors in order to decrease appetite as preventive action. In addition, various delivery technologies such as pH-sensitive, mucoadhesive, time-dependent, and enzyme-sensitive systems for colonic targeting of nutrients delivery are described. Sustained colonic delivery of nutritional compounds could be one of the most promising approaches to prevent obesity and associated metabolic diseases by, e.g., sustained GLP-1 release.

Metabolic, Intestinal, and Cardiovascular Effects of Sotagliflozin Compared With Empagliflozin in Patients With Type 2 Diabetes: A Randomized, Double-Blind Study

OBJECTIVE

Inhibiting sodium-glucose cotransporters (SGLTs) improves glycemic and cardiovascular outcomes in patients with type 2 diabetes (T2D). We investigated the differential impact of selective SGLT2 inhibition and dual inhibition of SGLT1 and SGLT2 on multiple parameters.

RESEARCH DESIGN AND METHODS

Using a double-blind, parallel-group design, we randomized 40 patients with T2D and hypertension to receive the dual SGLT1 and SGLT2 inhibitor sotagliflozin 400 mg or the selective SGLT2 inhibitor empagliflozin 25 mg, with preexisting antihypertensive treatment, for 8 weeks. In an in-house testing site, mixed-meal tolerance tests (MMTTs) and other laboratory and clinical evaluations were used to study metabolic, intestinal, cardiovascular, and urinary parameters over 24 h.

RESULTS

Changes from baseline in glycemic and blood pressure control; intestinal, urine, and metabolic parameters; and cardiovascular biomarkers were generally similar with sotagliflozin and empagliflozin. During the breakfast MMTT, sotagliflozin significantly reduced incremental area under the curve (AUC) values for postprandial glucose, insulin, and glucose-dependent insulinotropic polypeptide (GIP) and significantly increased incremental AUCs for postprandial glucagon-like peptide 1 (GLP-1) relative to empagliflozin, consistent with sotagliflozin-mediated inhibition of intestinal SGLT1. These changes waned during lunch and dinner MMTTs. Both treatments significantly lowered GIP incremental AUCs relative to baseline over the 14 h MMTT interval; the most vigorous effect was seen with sotagliflozin soon after start of the first meal of the day. No serious or severe adverse events were observed.

CONCLUSIONS

Changes from baseline in glycemic and blood pressure control, cardiovascular biomarkers, and other parameters were comparable between sotagliflozin and empagliflozin. However, sotagliflozin but not empagliflozin inhibited intestinal SGLT1 after breakfast as shown by larger changes in postprandial glucose, insulin, GIP, and GLP-1 AUCs, particularly after breakfast. Additional study is warranted to assess the clinical relevance of transient SGLT1 inhibition and differences in incretin responses (NCT03462069).

Sodium-Glucose Cotransporter Inhibitors as Antidiabetic Drugs: Current Development and Future Perspectives

Sodium-glucose cotransporter 2 (SGLT-2) inhibitors (gliflozins) represent the most recently approved class of oral antidiabetic drugs. SGLT-2 overexpression in diabetic patients contributes significantly to hyperglycemia and related complications. Therefore, SGLT-2 became a highly interesting therapeutic target, culminating in the approval for clinical use of dapagliflozin and analogues in the past decade. Gliflozins improve glycemic control through a novel insulin-independent mechanism of action and, moreover, exhibit significant cardiorenal protective effects in both diabetic and nondiabetic subjects. Therefore, gliflozins have received increasing attention, prompting extensive structure-activity relationship studies and optimization approaches. The discovery that intestinal SGLT-1 inhibition can provide a novel opportunity to control hyperglycemia, through a multifactorial mechanism, recently encouraged the design of low adsorbable inhibitors selectively directed to the intestinal SGLT-1 subtype as well as of dual SGLT-1/SGLT-2 inhibitors, representing a compelling strategy to identify new antidiabetic drug candidates.

Promise of sodium-glucose co-transporter-2 inhibitors in heart failure with mildly reduced ejection fraction

Heart failure with mildly reduced ejection fraction (HFmrEF) is associated with comparable poor outcomes as other subtypes of heart failure and remains a medical unmet need due to the paucity of effective therapies. According to large cardiovascular (CV) outcome trials in patients with heart failure, sodium-glucose co-transporter-2 inhibitors (SGLT2is) reduce CV mortality and hospitalizations for heart failure in patients with heart failure across the spectrum of left ventricular ejection fraction (LVEF). There has been a lack of dedicated trials in HFmrEF. However, several large outcome trials in heart failure that enrolled patients with HFmrEF could provide a hint on the role of SGLT2is in this subgroup. This review focuses on CV effects of three major SGLT2is-dapagliflozin, empagliflozin, and sotagliflozin-in patients with HFmrEF. A narrative review of trials investigating the efficacy of each medication in treating heart failure with LVEF > 40% is provided with a focus on their LVEF subgroup analyses. The purpose of this review is to discuss the current state of evidence regarding the potential of SGLT2is in HFmrEF management. Current limited evidence suggests that SGLT2is might be a favourable treatment modality for patients with HFmrEF to reduce hospitalization for heart failure and CV mortality. This conclusion needs to be further supported by clear HFmrEF subgroup analysis of the existing trials. Further outcome trials involving sufficient patients with different subtypes of HFmrEF are needed to confirm and assess CV benefits of SGLT2is in HFmrEF. Possible mechanisms by which SGLT2is exert their cardioprotective effect are also described briefly.

Exendin-4 inhibits small intestinal glucose sensing and absorption through repression of T1R2/T1R3 sweet taste receptor signalling in streptozotocin diabetic mice

The small intestine, which is the area where sugars are absorbed, should be considered in the approaches developed for the treatment of diabetes. However, studies on small intestine damage in diabetic individuals, and the effects of current treatments on the small intestine are very limited. This is the first study to investigate the effects of exendin-4, a GLP-1 receptor agonist, on small intestine injury in diabetic mice. BALB/c male mice were divided into 4 groups for this study. The first group was given citrate buffer, the second group was given exendin-4, the third group was given streptozotocin (STZ), and the fourth group was given both exendin-4, and STZ. As the results, we determined a decrease in the edema and deterioration in the integrity of the villi, disruption in continuity of the brush border, fibrosis and enterocyte apoptosis, while the TNFα level and crypt cell proliferation were increased in the small intestinal tissue of exendin-4 treated STZ diabetic mice. Furthermore, the levels of duodenal tissue glucose, SGLT1, and GLUT2 were decreased, whereas there was an increase in GIP level in diabetic mice administered with exendin-4. Moreover, we determined that the sweet taste receptors T1R2/T1R3, downstream molecules PLCβ2, α-gustducin and associated secondary messengers IP3, cAMP, which were increased in the duodenal tissue of STZ-diabetic mice, decreased with exendin-4 administration. These findings were evaluated as that exendin-4 reduces glucose absorption by suppressing the T1R2/T1R3 sweet taste signal perception pathway in duodenum of STZ diabetic mice.

Roles of glucose-dependent insulinotropic polypeptide in diet-induced obesity

Glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) are incretins that play an important role in glucose metabolism, by increasing glucose-induced insulin secretion from pancreatic β-cells and help regulate bodyweight. Although they show a similar action on glucose-induced insulin secretion, two incretins are distinct in various aspects. GIP is secreted from enteroendocrine K cell mainly expressed in the upper small intestine, and GLP-1 is secreted from enteroendocrine L cells mainly expressed in the lower small intestine and colon by the stimulation of various nutrients. The mechanism of GIP secretion induced by nutrients, especially carbohydrates, is different from that of GLP-1 secretion. GIP promotes fat deposition in adipose tissue, and contributes to fat-induced obesity. In contrast, GLP-1 participates in reducing bodyweight by suppressing food consumption and/or slowing gastric emptying. There is substantial evidence that GIP and GLP-1 might differently contribute to bodyweight control. Although meal contents influence both glycemic and weight control, we do not fully understand whether incretin actions differ depending on the contents of the meal and what kind of signaling is involved in its context. We focus on the molecular mechanism of GIP secretion induced by nutrients, as well as the roles of GIP in weight changes caused by various diets.

Effects of ileal glucose infusion on enteropancreatic hormone secretion in humans: relationship to glucose absorption

BACKGROUNDS

The distal small intestine plays an important role in regulating the secretion of entero-pancreatic hormones that are critical to the control of glucose metabolism and appetite, but the quantitative contribution of a specific segment to these effects is unknown.

PURPOSES

To determine the effects of 30 cm of the ileum exposed to glucose on the secretion of ghrelin, glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP) insulin, C-peptide and glucagon, in relation to glucose absorption in non-diabetic subjects.

BASIC PROCEDURES

10 non-diabetic subjects with a loop ileostomy after early-stage rectal cancer resection were studied on 2 days in a double-blind, randomized and crossover fashion, when a catheter was inserted retrogradely 30 cm from the ileostomy for infusion of a glucose solution containing 30 g glucose and 3 g 3-O-methylglucose (as a marker of active glucose absorption), or 0.9% saline, over 60 min. Ghrelin, GIP, GLP-1, insulin, C-peptide, glucagon and ileal glucose absorption (from concentrations of 3-O-methylglucose in serum and glucose in ileostomy effluent) were measured over 180 min.

MAIN FINDINGS

12.0 ± 1.2 g glucose was absorbed over 180 min. Compared to saline, ileal glucose resulted in minimal increases in blood glucose and plasma insulin and C-peptide, but substantial increases in plasma GLP-1, without affecting ghrelin, GIP or glucagon. The magnitude of the GLP-1 response to glucose was strongly related to the increase in serum 3-O-methylglucose.

PRINCIPAL CONCLUSIONS

Stimulation of the terminal ileum by glucose, even over a short length (30 cm), induces substantial GLP-1 release, coupled primarily to active glucose absorption.

CLINICAL REGISTRATION

NCT05030376 (ClinicalTrials.gov).

Glucose-Dependent Insulinotropic Polypeptide-A Postprandial Hormone with Unharnessed Metabolic Potential

Glucose-dependent insulinotropic polypeptide (GIP) is released from the upper small intestine in response to food intake and contributes to the postprandial control of nutrient disposition, including of sugars and fats. Long neglected as a potential therapeutic target, the GIPR axis has received increasing interest recently, with the emerging data demonstrating the metabolically favorable outcomes of adding GIPR agonism to GLP-1 receptor agonists in people with type 2 diabetes and obesity. This review examines the physiology of the GIP axis, from the mechanisms underlying GIP secretion from the intestine to its action on target tissues and therapeutic development. Expected final online publication date for the Annual Review of Nutrition, Volume 42 is August 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Anti-Diabetic Intestinal Mechanisms: Foods, Herbs, and Western Medicines

The role of intestinal factors in the pathogenesis of diabetes, such as a decrease in the incretin effect, has recently attracted considerable attention. An imbalance in the gut microbiota inhibits the secretion of incretins, which are metabolic hormones can reduce blood glucose levels, and promotes the occurrence and development of diabetes. Numerous studies have demonstrated that foods are environmental factors that are important in the modulation of gut microbial-mediated glucose metabolism. In general, functional foods trigger the gut microbiota to produce beneficial metabolites or reduce harmful products through metabolic pathways and then regulate glucose and lipid metabolism. Recent studies have shown that similar to functional foods, the regulatory effects of some herbs and Western medicines are closely related to alterations in the gut microbiota. In this review, the intestinal mechanism of foods, herbs, and Western medicine in affecting the process of glucose metabolism is summarized.

The Role of D-allulose and Erythritol on the Activity of the Gut Sweet Taste Receptor and Gastrointestinal Satiation Hormone Release in Humans: A Randomized, Controlled Trial

BACKGROUND

Glucose induces the release of gastrointestinal (GI) satiation hormones, such as glucagon-like peptide 1 (GLP-1) and peptide tyrosine tyrosine (PYY), in part via the activation of the gut sweet taste receptor (T1R2/T1R3).

OBJECTIVES

The primary objective was to investigate the importance of T1R2/T1R3 for the release of cholecystokinin (CCK), GLP-1, and PYY in response to D-allulose and erythritol by assessing the effect of the T1R2/T1R3 antagonist lactisole on these responses and as secondary objectives to study the effect of the T1R2/T1R3 blockade on gastric emptying, appetite-related sensations, and GI symptoms.

METHODS

In this randomized, controlled, double-blind, crossover study, 18 participants (5 men) with a mean ± SD BMI (in kg/m2) of 21.9 ± 1.7 and aged 24 ± 4 y received an intragastric administration of 25 g D-allulose, 50 g erythritol, or tap water, with or without 450 parts per million (ppm) lactisole, respectively, in 6 different sessions. 13C-sodium acetate was added to all solutions to determine gastric emptying. At fixed time intervals, blood and breath samples were collected, and appetite-related sensations and GI symptoms were assessed. Data were analyzed with linear mixed-model analysis.

RESULTS

D-allulose and erythritol induced a significant release of CCK, GLP-1, and PYY compared with tap water (all PHolm < 0.0001, dz >1). Lactisole did not affect the D-allulose- and erythritol-induced release of CCK, GLP-1, and PYY (all PHolm > 0.1). Erythritol significantly delayed gastric emptying, increased fullness, and decreased prospective food consumption compared with tap water (PHolm = 0.0002, dz = -1.05; PHolm = 0.0190, dz = 0.69; and PHolm = 0.0442, dz = -0.62, respectively).

CONCLUSIONS

D-allulose and erythritol stimulate the secretion of GI satiation hormones in humans. Lactisole had no effect on CCK, GLP-1, and PYY release, indicating that D-allulose- and erythritol-induced GI satiation hormone release is not mediated via T1R2/T1R3 in the gut.

Decreased expression of Glucagon-like peptide-1 receptor and Sodium-glucose co-transporter 2 in patients with proliferative diabetic retinopathy

PURPOSE

To investigate the expression of Glucagon-like peptide-1 receptor (GLP-1R), sodium-glucose co-transporter (SGLT) 1, SGLT2, Glucose transporter type 1 (GLUT1) and GLUT2 in patients with diabetic retinopathy (DR).

METHODS

We obtained peripheral blood mononuclear cells (PBMCs) and vitreous samples from 26 proliferative DR (PDR) patients, 25 non-proliferative DR (NPDR) patients, 25 non-DR (NDR) patients, and 26 nondiabetic patients with idiopathic epiretinal membranes (ERMs, control). The protein level and mRNA expression level of GLP-1R were quantified by immunoblot and qRT-PCR and the levels of SGLT1, SGLT2, GLUT1, and GLUT2 expression were determined by PCR. Their association with clinical parameters and PBMCs/vitreous cytokine was analyzed. Furthermore, immunofluorescence staining of GLP-1R and SGLT2 was carried out on samples of fibrovascular membranes (FVMs) retrieved from 26 patients with PDR and 26 patients with ERMs.

RESULTS

The transcriptional levels of GLP-1R and SGLT2 in PBMCs were significantly more decreased in PDR patients than in patients without DR and controls, which was simultaneously associated with an increased level of expression of tumor necrosis factor (TNF)-α and interferon (IFN)-γ. The expression levels of GLUT1 and GLUT2 were tightly correlated with their SGLT partners, respectively. Further, Immunofluorescence staining showed no positive staining of GLP-1R and SGLT2 was detected in the FVMs from PDR.

CONCLUSIONS

GLP-1R and SGLT2 were significantly decreased in PDR patients which was associated with an increased level of expression of TNF-α and IFN-γ. These findings implicate that defective GLP-1R and SGLT2 signaling may potentially correlate with immune response cytokines in patients with PDR.

Luminal Chemosensory Cells in the Small Intestine

In addition to the small intestine's well-known function of nutrient absorption, the small intestine also plays a major role in nutrient sensing. Similar to taste sensors seen on the tongue, GPCR-coupled nutrient sensors are expressed throughout the intestinal epithelium and respond to nutrients found in the lumen. These taste receptors respond to specific ligands, such as digested carbohydrates, fats, and proteins. The activation of nutrient sensors in the intestine allows for the induction of signaling pathways needed for the digestive system to process an influx of nutrients. Such processes include those related to glucose homeostasis and satiety. Defects in intestinal nutrient sensing have been linked to a variety of metabolic disorders, such as type 2 diabetes and obesity. Here, we review recent updates in the mechanisms related to intestinal nutrient sensors, particularly in enteroendocrine cells, and their pathological roles in disease. Additionally, we highlight the emerging nutrient sensing role of tuft cells and recent work using enteroids as a sensory organ model.

Protective effect of SGL5213, a potent intestinal sodium-glucose cotransporter 1 inhibitor, in nonalcoholic fatty liver disease in mice

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic disease. SGL5213, which is minimally absorbed and is restricted to the intestinal tract, is a potent intestinal sodium-glucose cotransporter 1 (SGLT1) inhibitor. In this study, we investigated the protective effect of SGL5213 in a rodent model of NAFLD.

METHODS

Using a rodent model of NAFLD, we compared SGL5213 efficacy with miglitol, which is an α-glucosidase inhibitor. We used a high-fat and high-sucrose diet-induced NAFLD model.

RESULTS

SGL5213 and miglitol improved obesity, liver dysfunction, insulin resistance, and the NAFLD severity. To further investigate the effects of SGL5213, we analyzed the mRNA expression of genes involved in lipid metabolism, inflammation, and liver fibrosis, and cecal pH levels. SGL5213 and miglitol treatment significantly decreased mRNA expression of factors involved in inflammation and liver fibrosis. SGL5213 treatment significantly decreased cecal pH levels, which did not occur with miglitol.

CONCLUSIONS

SGL5213 had a protective effect on the pathogenesis of NAFLD in a rodent model. We considered that inhibiting glucose absorption and increasing glucose content in the gastrointestinal tract with SGL5213 might have contributed to the protective effect in NAFLD. SGL5213 is a promising therapeutic agent for NAFLD with obesity and insulin resistance.

Canagliflozin increases intestinal adenoma burden in female Apc Min/+ mice

The diabetes drug canagliflozin extends lifespan in male mice. Since malignant neoplasms are the major cause of death in most mouse strains, this observation suggests that canagliflozin might exert anti-neoplastic effects in male mice. Here, we treated a mouse neoplasia model, the adenoma-prone Apc Min/+ strain, with canagliflozin, to test the effects of this drug on intestinal tumor burden. Surprisingly, canagliflozin increased the total area of intestine involved by adenomas, an effect most marked in the distal intestine and in female mice. Immunohistochemical analysis suggested that canagliflozin may not influence adenoma growth via direct SGLT1/2 inhibition in neoplastic cells. Our results are most consistent with a model where canagliflozin aggravates adenoma development by altering the anatomic distribution of intestinal glucose absorption, as evidenced by increases in postprandial GLP-1 levels driven by delayed glucose absorption. We hypothesize that canagliflozin exacerbates adenomatosis in the Apc Min/+ model via complex, cell-non-autonomous mechanisms, and that sex differences in GLP-1 responses may in part underlie sexually dimorphic effects of this drug on lifespan.

Reappraising the role of the vagus nerve in GLP-1-mediated regulation of eating

Here, we provide a focused review of the evidence for the roles of the vagus nerve in mediating the regulatory effects of peripherally and centrally produced GLP-1 on eating behaviour and energy balance. We particularly focus on recent studies which have used selective genetic, viral, and transcriptomic approaches to provide important insights into the anatomical and functional organisation of GLP-1-mediated gut-brain signalling pathways. A number of these studies have challenged canonical ideas of how GLP-1 acts in the periphery and the brain to regulate eating behaviour, with important implications for the development of pharmacological treatments for obesity.

Changes in the transcriptional activity of the entero-insular axis genes in streptozotocin-induced diabetes and after the administration of TNF-α non-selective blockers

OBJECTIVE

The aim of the present study was to investigate the transcriptional activity of the GLP-1R, DPP-4, SGLT-1, INSR, and IGF-1R genes in GALT cells of rats with streptozotocin-induced diabetes in both untreated and treated with pentoxifylline, as a non-specific blocker of TNF-α.

METHODS

The expression of GLP-1R, DPP-4, SGLT-1, INSR, and IGF-1R genes in GALT cells of rats was studied by real time quantitative polymerase chain reaction.

RESULTS

It was shown that the development of diabetes was accompanied by the decrease of GLP-1R and an increase of DPP-4 genes expression in rat ileum. The administration of pentoxifyl-line to diabetic animals led to an increase in the transcriptional activity of GLP-1R on the 4th week and decrease in transcriptional activity of DPP-4 on the 2nd and 4th weeks of the experiment. An increase in the normalized expression of SGLT-1 on the 4th week of the experimental diabetes was also noted, while the administration of pentoxifylline to diabetic animals did not lead to significant changes in this index. The transcriptional activity of the INSR and IGF-1R genes was reduced in diabetic rats and the administration of the non-specific TNF-α blocker - pentoxifylline led to a significant increase only for INSR gene in animals on the 4th week of the experimental diabetes.

CONCLUSIONS

The expression of incretins, glucose transporters, and pro-inflammatory cytokines (e.g. TNF-α) in immune cells may be used as markers of several autoimmune pathologies progression such as type 1 diabetes due to their effect on the balance of pro- and anti-inflammatory factors.

Chemosensing in enteroendocrine cells: mechanisms and therapeutic opportunities

PURPOSE OF REVIEW

Enteroendocrine cells (EECs) are scattered chemosensory cells in the intestinal epithelium that release hormones with a wide range of actions on intestinal function, food intake and glucose homeostasis. The mechanisms by which gut hormones are secreted postprandially, or altered by antidiabetic agents and surgical interventions are of considerable interest for future therapeutic development.

RECENT FINDINGS

EECs are electrically excitable and express a repertoire of G-protein coupled receptors that sense nutrient and nonnutrient stimuli, coupled to intracellular Ca2+ and cyclic adenosine monophosphate. Our knowledge of EEC function, previously developed using mouse models, has recently been extended to human cells. Gut hormone release in humans is enhanced by bariatric surgery, as well as by some antidiabetic agents including sodium-coupled glucose transporter inhibitors and metformin.

SUMMARY

EECs are important potential therapeutic targets. A better understanding of their chemosensory mechanisms will enhance the development of new therapeutic strategies to treat metabolic and gastrointestinal diseases.

Postprandial Hyperglycemia Stimulates Neuroglial Plasticity in Hypothalamic POMC Neurons after a Balanced Meal

Mechanistic studies in rodents evidenced synaptic remodeling in neuronal circuits that control food intake. However, the physiological relevance of this process is not well defined. Here, we show that the firing activity of anorexigenic POMC neurons located in the hypothalamus is increased after a standard meal. Postprandial hyperactivity of POMC neurons relies on synaptic plasticity that engages pre-synaptic mechanisms, which does not involve structural remodeling of synapses but retraction of glial coverage. These functional and morphological neuroglial changes are triggered by postprandial hyperglycemia. Chemogenetically induced glial retraction on POMC neurons is sufficient to increase POMC activity and modify meal patterns. These findings indicate that synaptic plasticity within the melanocortin system happens at the timescale of meals and likely contributes to short-term control of food intake. Interestingly, these effects are lost with a high-fat meal, suggesting that neuroglial plasticity of POMC neurons is involved in the satietogenic properties of foods.

Nutrient-Induced Cellular Mechanisms of Gut Hormone Secretion

The gastrointestinal tract can assess the nutrient composition of ingested food. The nutrient-sensing mechanisms in specialised epithelial cells lining the gastrointestinal tract, the enteroendocrine cells, trigger the release of gut hormones that provide important local and central feedback signals to regulate nutrient utilisation and feeding behaviour. The evidence for nutrient-stimulated secretion of two of the most studied gut hormones, glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), along with the known cellular mechanisms in enteroendocrine cells recruited by nutrients, will be the focus of this review. The mechanisms involved range from electrogenic transporters, ion channel modulation and nutrient-activated G-protein coupled receptors that converge on the release machinery controlling hormone secretion. Elucidation of these mechanisms will provide much needed insight into postprandial physiology and identify tractable dietary approaches to potentially manage nutrition and satiety by altering the secreted gut hormone profile.

The metabolic impact of small intestinal nutrient sensing

The gastrointestinal tract maintains energy and glucose homeostasis, in part through nutrient-sensing and subsequent signaling to the brain and other tissues. In this review, we highlight the role of small intestinal nutrient-sensing in metabolic homeostasis, and link high-fat feeding, obesity, and diabetes with perturbations in these gut-brain signaling pathways. We identify how lipids, carbohydrates, and proteins, initiate gut peptide release from the enteroendocrine cells through small intestinal sensing pathways, and how these peptides regulate food intake, glucose tolerance, and hepatic glucose production. Lastly, we highlight how the gut microbiota impact small intestinal nutrient-sensing in normal physiology, and in disease, pharmacological and surgical settings. Emerging evidence indicates that the molecular mechanisms of small intestinal nutrient sensing in metabolic homeostasis have physiological and pathological impact as well as therapeutic potential in obesity and diabetes.

The gastrointestinal tract participates in maintaining metabolic homeostasis in part through nutrient-sensing and subsequent gut-brain signalling. Here the authors review the role of small intestinal nutrient-sensing in regulation of energy intake and systemic glucose metabolism, and link high-fat diet, obesity and diabetes with perturbations in these pathways.

Metabolic Messengers: glucagon-like peptide 1

Glucagon like peptide-1 (GLP-1), a peptide hormone from the intestinal tract, plays a central role in the coordination of postprandial glucose homeostasis through actions on insulin secretion, food intake and gut motility. GLP-1 forms the basis for a variety of current drugs for the treatment of type 2 diabetes and obesity, as well as new agents currently being developed. Here, we provide a concise overview of the core physiology of GLP-1 secretion and action, and the role of the peptide in human health, disease and therapeutics.

Pathophysiology of SARS-CoV-2 in Lung of Diabetic Patients

Novel coronavirus disease (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Its impact on patients with comorbidities is clearly related to fatality cases, and diabetes has been linked to one of the most important causes of severity and mortality in SARS-CoV-2 infected patients. Substantial research progress has been made on COVID-19 therapeutics; however, effective treatments remain unsatisfactory. This unmet clinical need is robustly associated with the complexity of pathophysiological mechanisms described for COVID-19. Several key lung pathophysiological mechanisms promoted by SARS-CoV-2 have driven the response in normoglycemic and hyperglycemic subjects. There is sufficient evidence that glucose metabolism pathways in the lung are closely tied to bacterial proliferation, inflammation, oxidative stress, and pro-thrombotic responses, which lead to severe clinical outcomes. It is also likely that SARS-CoV-2 proliferation is affected by glucose metabolism of type I and type II cells. This review summarizes the current understanding of pathophysiology of SARS-CoV-2 in the lung of diabetic patients and highlights the changes in clinical outcomes of COVID-19 in normoglycemic and hyperglycemic conditions.

Role of intestinal glucose absorption in glucose tolerance

Intestinal glucose absorption is integral to postprandial glucose homeostasis. Glucose absorption is dependent on a number of factors, including the exposure of carbohydrate to the mucosa of the upper gastrointestinal tract (determined particularly by the rates of gastric emptying and small intestinal transit), the digestion of complex carbohydrate into monosaccharides, and glucose sensing and transport by the intestinal mucosa. The absorption of glucose in the small intestine is not only a determinant of the appearance of exogenous glucose in the peripheral circulation, but is also coupled to the release of gastrointestinal hormones that in turn influence postprandial glucose metabolism through modulating gastrointestinal motor function, insulin and glucagon secretion, and subsequent energy intake. This review describes the physiology and pathophysiology of intestinal glucose absorption in health and type 2 diabetes, including its relevance to glucose tolerance and the management of postprandial hyperglycaemia.

Adjunct therapies in treatment of type 1 diabetes

In spite of developments with novel insulin preparations, novel modes of insulin delivery with insulin infusion pumps, and the facility of continuous glucose monitoring, only 20% of patients with type 1 diabetes are under adequate control. The need for innovation is clear, and, therefore, the use of adjunct therapies with other pharmacological agents currently in use for type 2 diabetes, has been tried. Currently, pramlintide is the only agent licensed for use in this condition in addition to insulin. Global trials have been conducted with liraglutide, a glucagon-like peptide 1 receptor agonist (GLP-1RA), dapagliflozin, a sodium glucose cotransporter 2 (SGLT2) inhibitor, and sotagliflozin, an inhibitor of both SGLT1 and SGLT2 transporters. While dapagliflozin and sotagliflozin have now been licensed for clinical use in this condition in Europe and Japan, they have hitherto not been licensed in the United States due to a small increase in the risk of diabetic ketoacidosis. However, these agents reduce glycosylated hemoglobin (HbA1c) by 0.4%, reduce glycemic oscillations, and do not increase the risk of hypoglycemia. Liraglutide, on the other hand, induced a smaller reduction in HbA1c and thus was not considered for a license. However, further trials are currently being conducted with a combination of semaglutide, the most potent GLP-1RA, and dapagliflozin to determine whether this approach would yield better outcomes.

Fucoidan from Ascophyllum nodosum Suppresses Postprandial Hyperglycemia by Inhibiting Na+/Glucose Cotransporter 1 Activity

We previously demonstrated that fucoidan with a type II structure inhibited postprandial hyperglycemia by suppressing glucose uptake, but the mechanism remains elusive. Here, we aimed to assess whether the effect of glucose absorption inhibition was related to the basic structure of fucoidans and preliminarily clarified the underlying mechanism. Fucoidans with type II structure and type I structure were prepared from Ascophyllumnodosum (AnF) or Laminariajaponica (LjF) and Kjellmaniellacrassifolia (KcF), respectively. The effects of various fucoidans on suppressing postprandial hyperglycemia were investigated using in vitro (Caco-2 monolayer model), semi-in vivo (everted gut sac model), and in vivo (oral glucose tolerance test, OGTT) assays. The results showed that only AnF with a type II structure, but not LjF or KcF with type I structure, could inhibit the glucose transport in the Caco-2 monolayer and everted gut sac models. A similar result was seen in the OGTT of Kunming mice and leptin receptor-deficient (db/db) mice, where only AnF could effectively inhibit glucose transport into the bloodstream. Furthermore, AnF (400 mg/kg/d) treatment decreased the fasting blood glucose, HbA1c, and fasting insulin levels, while increasing the serum glucagon-like peptide-1 (GLP-1) level in obese leptin receptor-deficient (db/db) mice. Furthermore, surface plasmon resonance (SPR) analysis revealed the specific binding of AnF to Na+/glucose cotransporter 1 (SGLT1), which indicated the effect of AnF on postprandial hyperglycemia could be due to its suppression on SGLT1 activity. Taken together, this study suggests that AnF with a type II structure can be a promising candidate for hyperglycemia treatment.

SGLT2 is not expressed in pancreatic α- and β-cells, and its inhibition does not directly affect glucagon and insulin secretion in rodents and humans

Objective

Sodium-glucose cotransporter 2 (SGLT2) inhibitors (SGLT2i), or gliflozins, are anti-diabetic drugs that lower glycemia by promoting glucosuria, but they also stimulate endogenous glucose and ketone body production. The likely causes of these metabolic responses are increased blood glucagon levels, and decreased blood insulin levels, but the mechanisms involved are hotly debated. This study verified whether or not SGLT2i affect glucagon and insulin secretion by a direct action on islet cells in three species, using multiple approaches.

Methods

We tested the in vivo effects of two selective SGLT2i (dapagliflozin, empagliflozin) and a SGLT1/2i (sotagliflozin) on various biological parameters (glucosuria, glycemia, glucagonemia, insulinemia) in mice. mRNA expression of SGLT2 and other glucose transporters was assessed in rat, mouse, and human FACS-purified α- and β-cells, and by analysis of two human islet cell transcriptomic datasets. Immunodetection of SGLT2 in pancreatic tissues was performed with a validated antibody. The effects of dapagliflozin, empagliflozin, and sotagliflozin on glucagon and insulin secretion were assessed using isolated rat, mouse and human islets and the in situ perfused mouse pancreas. Finally, we tested the long-term effect of SGLT2i on glucagon gene expression.

Results

SGLT2 inhibition in mice increased the plasma glucagon/insulin ratio in the fasted state, an effect correlated with a decline in glycemia. Gene expression analyses and immunodetections showed no SGLT2 mRNA or protein expression in rodent and human islet cells, but moderate SGLT1 mRNA expression in human α-cells. However, functional experiments on rat, mouse, and human (29 donors) islets and the in situ perfused mouse pancreas did not identify any direct effect of dapagliflozin, empagliflozin or sotagliflozin on glucagon and insulin secretion. SGLT2i did not affect glucagon gene expression in rat and human islets.

Conclusions

The data indicate that the SGLT2i-induced increase of the plasma glucagon/insulin ratio in vivo does not result from a direct action of the gliflozins on islet cells.

•

Gliflozins (SGLT2 and SGLT1/2 inhibitors) increase plasma glucagon/insulin ratio.

•

SGLT2 is not expressed in rodent and human pancreatic α- and β-cells.

•

SGLT1 is however expressed in human α-cells.

•

SGLT2 and SGLT1/2 inhibitors do not directly affect glucagon and insulin secretion.

Enteroendocrine Hormone Secretion and Metabolic Control: Importance of the Region of the Gut Stimulation

It is now widely appreciated that gastrointestinal function is central to the regulation of metabolic homeostasis. Following meal ingestion, the delivery of nutrients from the stomach into the small intestine (i.e., gastric emptying) is tightly controlled to optimise their subsequent digestion and absorption. The complex interaction of intraluminal nutrients (and other bioactive compounds, such as bile acids) with the small and large intestine induces the release of an array of gastrointestinal hormones from specialised enteroendocrine cells (EECs) distributed in various regions of the gut, which in turn to regulate gastric emptying, appetite and postprandial glucose metabolism. Stimulation of gastrointestinal hormone secretion, therefore, represents a promising strategy for the management of metabolic disorders, particularly obesity and type 2 diabetes mellitus (T2DM). That EECs are distributed distinctively between the proximal and distal gut suggests that the region of the gut exposed to intraluminal stimuli is of major relevance to the secretion profile of gastrointestinal hormones and associated metabolic responses. This review discusses the process of intestinal digestion and absorption and their impacts on the release of gastrointestinal hormones and the regulation of postprandial metabolism, with an emphasis on the differences between the proximal and distal gut, and implications for the management of obesity and T2DM.

The effect of acute dual SGLT1/SGLT2 inhibition on incretin release and glucose metabolism after gastric bypass surgery

Enhanced meal-related enteroendocrine secretion, particularly of glucagon-like peptide-1 (GLP-1), contributes to weight-loss and improved glycemia after Roux-en-Y gastric bypass (RYGB). Dietary glucose drives GLP-1 and glucose-dependent insulinotropic polypeptide (GIP) secretion postoperatively. Understanding how glucose triggers incretin secretion following RYGB could lead to new treatments of diabetes and obesity. In vitro, incretin release depends on glucose absorption via sodium-glucose cotransporter 1 (SGLT1). We investigated the importance of SGLT1/SGLT2 for enteropancreatic hormone concentrations and glucose metabolism after RYGB in a randomized, controlled, crossover study. Ten RYGB-operated patients ingested 50 g of oral glucose with and without acute pretreatment with 600 mg of the SGLT1/SGLT2-inhibitor canagliflozin. Paracetamol and 3-O-methyl-d-glucopyranose (3-OMG) were added to the glucose drink to evaluate rates of intestinal entry and absorption of glucose, respectively. Blood samples were collected for 4 h. The primary outcome was 4-h plasma GLP-1 (incremental area-under the curve, iAUC). Secondary outcomes included glucose, GIP, insulin, and glucagon. Canagliflozin delayed glucose absorption (time-to-peak 3-OMG: 50 vs. 132 min, P < 0.01) but did not reduce iAUC GLP-1 (6,067 vs. 7,273·min·pmol^-1·L^-1, P = 0.23), although peak GLP-1 concentrations were lowered (-28%, P = 0.03). Canagliflozin reduced GIP (iAUC -28%, P = 0.01; peak concentrations -57%, P < 0.01), insulin, and glucose excursions, whereas plasma glucagon (AUC 3,216 vs. 4,160 min·pmol·L^-1, P = 0.02) and amino acids were increased. In conclusion, acute SGLT1/SGLT2-inhibition during glucose ingestion did not reduce 4-h plasma GLP-1 responses in RYGB-patients but attenuated the early rise in GLP-1, GIP, and insulin, whereas late glucagon concentrations were increased. The results suggest that SGLT1-mediated glucose absorption contributes to incretin hormone secretion after RYGB.

Sotagliflozin Decreases Postprandial Glucose and Insulin Concentrations by Delaying Intestinal Glucose Absorption

CONTEXT

The effect of sotagliflozin (a dual sodium-glucose cotransporter [SGLT] 2 and SGLT1 inhibitor) on intestinal glucose absorption has not been investigated in humans.

OBJECTIVE

To measure rate of appearance of oral glucose (RaO) using a dual glucose tracer method following standardized mixed meals taken after single sotagliflozin or canagliflozin doses.

SETTING

Clinical research organization.

DESIGN AND PARTICIPANTS

In a double-blind, 3-period crossover study (NCT01916863), 24 healthy participants were randomized to 2 cohorts of 12 participants. Within each cohort, participants were randomly assigned single oral doses of either sotagliflozin 400 mg, canagliflozin 300 mg, or placebo on each of test days 1, 8, and 15. On test days, Cohort 1 had breakfast containing [6,6-2H2] glucose 0.25 hours postdose and lunch containing [1-2H1] glucose 5.25 hours postdose; Cohort 2 had breakfast containing no labeled glucose 0.25 hours postdose and lunch containing [6,6-2H2] glucose 4.25 hours postdose. All participants received a 10- to 15-hour continuous [U-13C6] glucose infusion starting 5 hours before their first [6,6-2H2] glucose-containing meal.

MAIN OUTCOME

RaO, postprandial glucose (PPG), and postprandial insulin.

RESULTS

Sotagliflozin and canagliflozin decreased area under the curve (AUC)0-1 hour and/or AUC0-2 hours for RaO, PPG, and insulin after breakfast and/or the 4.25-hour postdose lunch (P < .05 versus placebo). After the 5.25-hour postdose lunch, sotagliflozin lowered RaO AUC0-1 hour and PPG AUC0-5 hours versus both placebo and canagliflozin (P < .05).

CONCLUSIONS

Sotagliflozin delayed and blunted intestinal glucose absorption after meals, resulting in lower PPG and insulin levels, likely due to prolonged local inhibition of intestinal SGLT1 that persisted for ≥5 hours after dosing.

Cellular mechanisms governing glucose-dependent insulinotropic polypeptide secretion

Glucose-dependent insulinotropic polypeptide (GIP) is a gut hormone secreted from the upper small intestine, which plays an important physiological role in the control of glucose metabolism through its incretin action to enhance glucose-dependent insulin secretion. GIP has also been implicated in postprandial lipid homeostasis. GIP is secreted from enteroendocrine K-cells residing in the intestinal epithelium. K-cells sense a variety of components found in the gut lumen following food consumption, resulting in an increase in plasma GIP signal dependent on the nature and quantity of ingested nutrients. We review the evidence for an important role of sodium-coupled glucose uptake through SGLT1 for carbohydrate sensing, of free-fatty acid receptors FFAR1/FFAR4 and the monoacyl-glycerol sensing receptor GPR119 for lipid detection, of the calcium-sensing receptor CASR and GPR142 for protein sensing, and additional modulation by neurotransmitters such as somatostatin and galanin. These pathways have been identified through combinations of in vivo, in vitro and molecular approaches.

Performance-Enhanced Non-Enzymatic Glucose Sensor Based on Graphene-Heterostructure

Non-enzymatic glucose sensing is a crucial field of study because of the current market demand. This study proposes a novel design of glucose sensor with enhanced selectivity and sensitivity by using graphene Schottky diodes, which is composed of graphene (G)/platinum oxide (PtO)/n-silicon (Si) heterostructure. The sensor was tested with different glucose concentrations and interfering solutions to investigate its sensitivity and selectivity. Different structures of the device were studied by adjusting the platinum oxide film thickness to investigate its catalytic activity. It was found that the film thickness plays a significant role in the efficiency of glucose oxidation and hence in overall device sensitivity. 0.8-2 μA output current was obtained in the case of 4-10 mM with a sensitivity of 0.2 A/mM.cm2. Besides, results have shown that 0.8 A and 15 A were obtained by testing 4 mM glucose on two different PtO thicknesses, 30 nm and 50 nm, respectively. The sensitivity of the device was enhanced by 150% (i.e., up to 30 A/mM.cm2) by increasing the PtO layer thickness. This was attributed to both the increase of the number of active sites for glucose oxidation as well as the increase in the graphene layer thickness, which leads to enhanced charge carriers concentration and mobility. Moreover, theoretical investigations were conducted using the density function theory (DFT) to understand the detection method and the origins of selectivity better. The working principle of the sensors puts it in a competitive position with other non-enzymatic glucose sensors. DFT calculations provided a qualitative explanation of the charge distribution across the graphene sheet within a system of a platinum substrate with D-glucose molecules above. The proposed G/PtO/n-Si heterostructure has proven to satisfy these factors, which opens the door for further developments of more reliable non-enzymatic glucometers for continuous glucose monitoring systems.

Sotagliflozin: First Global Approval

Sotagliflozin (Zynquista™) is a dual inhibitor of sodium-glucose co-transporters (SGLT) 1 and 2 being developed by Lexicon Pharmaceuticals and Sanofi as a treatment for type 1 (T1DM) and type 2 diabetes mellitus (T2DM). The drug has a dual action, blunting and delaying absorption of glucose from the gastrointestinal tract and the reabsorption of glucose in the proximal tubule of the kidney, respectively. In the phase III inTandem clinical trial program in patients with T1DM, sotagliflozin as an adjunct to optimised insulin therapy produced a clinically meaningful reduction in HbA_1c levels, but was associated with a higher incidence of diabetic ketoacidosis than placebo. Sotagliflozin was recently approved for use as an adjunct to insulin in T1DM in the EU. However, the FDA Endocrinologic and Metabolic Drugs Advisory Committee was divided, citing concerns regarding diabetic ketoacidosis, leading the FDA to issue an Complete Response Letter for this indication in the USA. This article summarizes the milestones in the development of sotagliflozin leading to this first approval in the EU as an adjunct to insulin in patients with T1DM with a body mass index ≥ 27 kg/m² who have failed to achieve adequate glycaemic control despite optimal insulin therapy.

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.

Glycemic efficacy and safety of glucagon-like peptide-1 receptor agonist on top of sodium-glucose co-transporter-2 inhibitor treatment compared to sodium-glucose co-transporter-2 inhibitor alone: A systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

Sodium-glucose co-transporter-2 inhibitors (SGLT-2i) and glucagon-like peptide-1 receptor agonists (GLP-1RAs) are now considered as key players in the treatment of type 2 diabetes mellitus (T2DM). The purpose of this meta-analysis was to provide precise effect estimates regarding the safety and efficacy of the addition of a GLP-1RA on top of SGLT-2i treatment.

RESEARCH DESIGN AND METHODS

PubMed and CENTRAL, along with grey literature sources, were searched from their inception to May 2019 for randomized controlled trials (RCTs) with a duration ≥ 12 weeks, evaluating the safety and efficacy of addition of a GLP-1RA on a SGLT-2i compared to SGLT-2i alone in patients with T2DM. We also used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to assess the credibility of our summary estimates.

RESULTS

We identified three eligible RCTs, pooling data retrieved from 1,042 patients with T2DM in total. Administration of the maximum dose of a GLP-1RA on top of SGLT-2i treatment compared to SGLT-2i alone resulted in significant decrease in HbA1c by 0.91% (95% CI; -1.41 to -0.42) [GRADE: moderate], in body weight by 1.95 kg (95% CI; -3.83 to -0.07) [GRADE: moderate], in fasting plasma glucose by 1.53 mmol/L (95% CI; -2.17 to -0.88) [GRADE: moderate] and in systolic blood pressure levels by 3.64 mm Hg (95% CI -6.24 to -1.03). No significant effects on lipid profile and diastolic blood pressure were demonstrated. A significant increase in the risk for any hypoglycemia (RR: 2.62, 95% CI; 1.15-5.96, I² = 33%) [GRADE: moderate] and for nausea (RR: 3.21, 95% CI; 1.36-7.54, I² = 63%) [GRADE: moderate] and a non-significant increase in the risk for diarrhoea (RR: 1.64, 95% CI; 0.98-2.75, I² = 0%) [GRADE: low] were documented. No other safety issues were identified.

CONCLUSIONS

This meta-analysis suggests that a GLP-1RA/SGLT-2i combination, if tolerated, exerts significant beneficial effects on glycemic control and body weight loss, however increasing the risk for any hypoglycemia and gastrointestinal adverse events.

The Impact of Sotagliflozin on Renal Function, Albuminuria, Blood Pressure, and Hematocrit in Adults With Type 1 Diabetes

OBJECTIVE

In people with type 2 diabetes, sodium-glucose cotransporter 2 inhibitors (SGLT2i) reduce cardiovascular risk and progression of diabetic kidney disease. Our aim was to determine whether sotagliflozin (SOTA), a dual SGLT1i and SGLT2i, had favorable effects on clinical biomarkers suggestive of kidney protection in adults with type 1 diabetes.

RESEARCH DESIGN AND METHODS

In this 52-week pooled analysis, 1,575 adults enrolled in the inTandem1 and inTandem2 trials were randomized to SOTA 200 mg, 400 mg, or placebo in addition to optimized insulin therapy. Changes in cardiorenal biomarkers were assessed.

RESULTS

At 52 weeks, in response to SOTA 200 and 400 mg, the placebo-corrected least squares mean change from baseline in estimated glomerular filtration rate was -2.0 mL/min/1.73 m² (P = 0.010) and -0.5 mL/min/1.73 m² (P = 0.52), respectively. Systolic blood pressure difference was -2.9 and -3.6 mmHg (P < 0.0001 for both); diastolic blood pressure changed by -1.4 (P = 0.0033) and -1.6 mmHg (P = 0.0008). In participants with baseline urinary albumin-to-creatinine ratio (UACR) ≥30 mg/g, UACR decreased by 23.7% (P = 0.054) and 18.3% (P = 0.18) for SOTA 200 and SOTA 400 mg, respectively, versus placebo. Increases in serum albumin and hematocrit and reductions in uric acid were observed throughout 52 weeks with both SOTA doses.

CONCLUSIONS

SOTA was associated with short- and long-term renal hemodynamic changes, which were similar to those seen with SGLT2i in type 2 diabetes. Further investigation around cardiorenal effects of SOTA in people with type 1 diabetes is justified.

Effects of salbutamol and phlorizin on acute pulmonary inflammation and disease severity in experimental sepsis

Respiratory infection can be exacerbated by the high glucose concentration in the airway surface liquid (ASL). We investigated the effects of salbutamol and phlorizin on the pulmonary function, oxidative stress levels and SGLT1 activity in lung, pulmonary histopathological damages and survival rates of rats with sepsis. Sepsis was induced by cecal ligation and puncture surgery (CLP). Twenty-four hours after surgery, CLP rats were intranasally treated with saline, salbutamol or phlorizin. After 2 hours, animals were anesthetized and sacrificed. Sepsis promoted atelectasis and bronchial inflammation, and led to increased expression of SGLT1 on cytoplasm of pneumocytes. Salbutamol treatment reduced bronchial inflammation and promoted hyperinsuflation in CLP rats. The interferon-ɤ and Interleucin-1β concentrations in bronchoalveolar lavage (BAL) were closely related to the bronchial inflammation regulation. Salbutamol stimulated SGLT1 in plasma membrane; whereas, phlorizin promoted the increase of SGLT1 in cytoplasm. Phlorizin reduced catalase activity and induced a significant decrease in the survival rate of CLP rats. Taken together, sepsis promoted atelectasis and lung inflammation, which can be associated with SGLT1 inhibition. The loss of function of SGLT1 by phlorizin are related to the augmented disease severity, increased atelectasis, bronchial inflammation and a significant reduction of survival rate of CLP rats. Alternatively salbutamol reduced BAL inflammatory cytokines, bronchial inflammation, atelectasis, and airway damage in sepsis. These data suggest that this selective β2-adrenergic agonist may protect lung of septic acute effects.

Novel natural and synthetic inhibitors of solute carriers SGLT1 and SGLT2

Selective analogs of the natural glycoside phloridzin are marketed drugs that reduce hyperglycemia in diabetes by inhibiting the active sodium glucose cotransporter SGLT2 in the kidneys. In addition, intestinal SGLT1 is now recognized as a target for glycemic control. To expand available type 2 diabetes remedies, we aimed to find novel SGLT1 inhibitors beyond the chemical space of glycosides. We screened a bioactive compound library for SGLT1 inhibitors and tested primary hits and additional structurally similar molecules on SGLT1 and SGLT2 (SGLT1/2). Novel SGLT1/2 inhibitors were discovered in separate chemical clusters of natural and synthetic compounds. These have IC50-values in the 10-100 μmol/L range. The most potent identified novel inhibitors from different chemical clusters are (SGLT1-IC50 Mean ± SD, SGLT2-IC50 Mean ± SD): (+)-pteryxin (12 ± 2 μmol/L, 9 ± 4 μmol/L), (+)-ε-viniferin (58 ± 18 μmol/L, 110 μmol/L), quinidine (62 μmol/L, 56 μmol/L), cloperastine (9 ± 3 μmol/L, 9 ± 7 μmol/L), bepridil (10 ± 5 μmol/L, 14 ± 12 μmol/L), trihexyphenidyl (12 ± 1 μmol/L, 20 ± 13 μmol/L) and bupivacaine (23 ± 14 μmol/L, 43 ± 29 μmol/L). The discovered natural inhibitors may be further investigated as new potential (prophylactic) agents for controlling dietary glucose uptake. The new diverse structure activity data can provide a starting point for the optimization of novel SGLT1/2 inhibitors and support the development of virtual SGLT1/2 inhibitor screening models.