Increase in Endogenous Glucose Production With SGLT2 Inhibition Is Unchanged by Renal Denervation and Correlates Strongly With the Increase in Urinary Glucose Excretion

A kidney-hypothalamus axis promotes compensatory glucose production in response to glycosuria

The kidneys facilitate energy conservation through reabsorption of nutrients including glucose. Almost all the filtered blood glucose is reabsorbed by the kidneys. Loss of glucose in urine (glycosuria) is offset by an increase in endogenous glucose production to maintain normal energy supply in the body. How the body senses this glucose loss and consequently enhances glucose production is unclear. Using renal Glut2 knockout mice, we demonstrate that elevated glycosuria activates the hypothalamic-pituitary-adrenal axis, which in turn drives endogenous glucose production. This phenotype was attenuated by selective afferent renal denervation, indicating the involvement of the afferent nerves in promoting the compensatory increase in glucose production. In addition, through plasma proteomics analyses we observed that acute phase proteins - which are usually involved in body's defense mechanisms against a threat - were the top candidates which were either upregulated or downregulated in renal Glut2 KO mice. Overall, afferent renal nerves contribute to promoting endogenous glucose production in response to elevated glycosuria and loss of glucose in urine is sensed as a biological threat in mice. These findings may be useful in improving efficiency of drugs like SGLT2 inhibitors that are intended to treat hyperglycemia by enhancing glycosuria but are met with a compensatory increase in endogenous glucose production.

Emergence of a New Glucoregulatory Mechanism for Glycemic Control With Dapagliflozin/Exenatide Therapy in Type 2 Diabetes

CONTEXT

This study addresses the development of a new glucoregulatory mechanism in type 2 diabetes (T2D) patients treated with SGLT-2 inhibitors, which is independent of glucose, insulin and glucagon. The data suggest the presence of a potential trigger factor (s) arising in the kidney that stimulates endogenous glucose production (EGP) during sustained glycosuria.

OBJECTIVE

To investigate effects of SGLT-2 inhibitor therapy together with GLP-1 receptor agonist on EGP and glucose kinetics in patients with T2D. Our hypothesis was that increased EGP in response to SGLT2i-induced glycosuria persists for a long period and is not abolished by GLP-1 RA stimulation of insulin secretion and glucagon suppression.

METHODS

Seventy-five patients received a 5-hour dual-tracer oral glucose tolerance test (OGTT) (intravenous 3-(3H)-glucose oral (1-14C)-glucose): (1) before/after 1 of dapagliflozin (DAPA); exenatide (EXE), or both, DAPA/EXE (acute study), and (2) after 1 and 4 months of therapy with each drug.

RESULTS

In the acute study, during the OGTT plasma glucose (PG) elevation was lower in EXE (Δ = 42 ± 1 mg/dL) than DAPA (Δ = 72 ± 3), and lower in DAPA/EXE (Δ = 11 ± 3) than EXE and DAPA. EGP decrease was lower in DAPA (Δ = -0.65 ± 0.03 mg/kg/min) than EXE (Δ = -0.96 ± 0.07); in DAPA/EXE (Δ = -0.84 ± 0.05) it was lower than EXE, higher than DAPA. At 1 month, similar PG elevations (EXE, Δ = 26 ± 1 mg/dL; DAPA, Δ = 62 ± 2, DAPA/EXE, Δ = 27 ± 1) and EGP decreases (DAPA, Δ = -0.60 ± 0.05 mg/kg/min; EXE, Δ = -0.77 ± 0.04; DAPA/EXE, Δ = -0.72 ± 0.03) were observed. At 4 months, PG elevations (EXE, Δ = 55 ± 2 mg/dL; DAPA, Δ = 65 ± 6; DAPA/EXE, Δ = 46 ± 2) and lower EGP decrease in DAPA (Δ = -0.66 ± 0.04 mg/kg/min) vs EXE (Δ = -0.84 ± 0.05) were also comparable; in DAPA/EXE (Δ = -0.65 ± 0.03) it was equal to DAPA and lower than EXE. Changes in plasma insulin/glucagon could not explain higher EGP in DAPA/EXE vs EXE mg/kg/min.

CONCLUSION

Our findings provide strong evidence for the emergence of a new long-lasting, glucose-independent, insulin/glucagon-independent, glucoregulatory mechanism via which SGLT2i-induced glycosuria stimulates EGP in patients with T2D. SGLT2i plus GLP-1 receptor agonist combination therapy is accompanied by superior glycemic control vs monotherapy.

Fluid homeostatic action of dapagliflozin in patients with chronic kidney disease: the DAPA-BODY Trial

Sodium glucose cotransporter 2 (SGLT2) inhibitors have both glucose-lowering and diuretic effects. We recently reported that the SGLT2 inhibitor dapagliflozin exerts short-term fluid homeostatic action in patients with chronic kidney disease (CKD). However, the long-term effects of SGLT2 inhibitors on body fluid status in patients with CKD remain unclear. This was a prospective, non-randomized, open-label study that included a dapagliflozin treatment group (n = 73) and a control group (n = 24) who were followed for 6 months. Body fluid volume was measured using a bioimpedance analysis device. The extracellular water-to-total body water ratio (ECW/TBW), a predictor of renal outcomes, was used as a parameter for body fluid status (fluid retention, 0.400 ≤ ECW/TBW). Six-month treatment with dapagliflozin significantly decreased ECW/TBW compared with the control group (-0.65% ± 2.03% vs. 0.97% ± 2.49%, p = 0.0018). Furthermore, dapagliflozin decreased the ECW/TBW in patients with baseline fluid retention, but not in patients without baseline fluid retention (-1.47% ± 1.93% vs. -0.01% ± 1.88%, p = 0.0017). Vasopressin surrogate marker copeptin levels were similar between the control and dapagliflozin groups at 6 months (32.3 ± 33.4 vs. 30.6 ± 30.1 pmol/L, p = 0.8227). However, dapagliflozin significantly increased the change in copeptin levels at 1 week (39.0% ± 41.6%, p = 0.0010), suggesting a compensatory increase in vasopressin secretion to prevent hypovolemia. Renin and aldosterone levels were similar between the control and dapagliflozin groups at 6 months, while epinephrine and norepinephrine (markers of sympathetic nervous system activity) were significantly lower in the dapagliflozin group than in the control group. In conclusion, the SGLT2 inhibitor dapagliflozin ameliorated fluid retention and maintained euvolemic fluid status in patients with CKD, suggesting that SGLT2 inhibitors exert sustained fluid homeostatic actions in patients with various fluid backgrounds. Clinical trial registration: https://www.umin.ac.jp/ctr/, identifier [UMIN000048568].

Renal Glucose Release after Unilateral Renal Denervation during a Hypoglycemic Clamp in Pigs with an Altered Hypothalamic Pituitary Adrenal Axis after Late-Gestational Dexamethasone Injection

Previously, we demonstrated in pigs that renal denervation halves glucose release during hypoglycaemia and that a prenatal dexamethasone injection caused increased ACTH and cortisol concentrations as markers of a heightened hypothalamic pituitary adrenal axis (HPAA) during hypoglycaemia. In this study, we investigated the influence of an altered HPAA on renal glucose release during hypoglycaemia. Pigs whose mothers had received two late-gestational dexamethasone injections were subjected to a 75 min hyperinsulinaemic-hypoglycaemic clamp (<3 mmol/L) after unilateral surgical denervation. Para-aminohippurate (PAH) clearance, inulin, sodium excretion and arterio-venous blood glucose difference were measured every fifteen minutes. The statistical analysis was performed with a Wilcoxon signed-rank test. PAH, inulin, the calculated glomerular filtration rate and plasma flow did not change through renal denervation. Urinary sodium excretion increased significantly (p = 0.019). Side-dependent renal net glucose release (SGN) decreased by 25 ± 23% (p = 0.004). At 25 percent, the SGN decrease was only half of that observed in non-HPAA-altered animals in our prior investigation. The current findings may suggest that specimens with an elevated HPAA undergo long-term adaptations to maintain glucose homeostasis. Nonetheless, the decrease in SGN warrants further investigations and potentially caution in performing renal denervation in certain patient groups, such as diabetics at risk of hypoglycaemia.

Cardiorenal protection of SGLT2 inhibitors—Perspectives from metabolic reprogramming

Sodium-glucose co-transporter 2 (SGLT2) inhibitors, initially developed as a novel class of anti-hyperglycaemic drugs, have been shown to significantly improve metabolic indicators and protect the kidneys and heart of patients with or without type 2 diabetes mellitus. The possible mechanisms mediating these unexpected cardiorenal benefits are being extensively investigated because they cannot solely be attributed to improvements in glycaemic control. Notably, emerging data indicate that metabolic reprogramming is involved in the progression of cardiorenal metabolic diseases. SGLT2 inhibitors reprogram systemic metabolism to a fasting-like metabolic paradigm, involving the metabolic switch from carbohydrates to other energetic substrates and regulation of the related nutrient-sensing pathways, which might explain some of their cardiorenal protective effects. In this review, we will focus on the current understanding of cardiorenal protection by SGLT2 inhibitors, specifically its relevance to metabolic reprogramming.

Emerging roles of Sodium-glucose cotransporter 2 inhibitors in Diabetic kidney disease

Diabetic kidney disease (DKD), a severe microvascular complication of diabetes mellitus, is the primary cause of end stage renal disease (ESRD). Sodium-glucose cotransporter 2 (SGLT2) inhibitors are a class of novel anti-diabetic drugs for DKD, which have the potential to prevent renal function from failing. The involved mechanisms have garnered considerable attention. Besides hypoglycemic effect, it seems that various glucose-independent nephroprotective mechanisms also have a role. Among them, improvement in tubuloglomerular feedback is considered as the main reason, followed by reduced intraglomerular pressure and fluid load. In addition, reduced blood pressure, anti-inflammatory effects, nutrient deprivation signaling as well as improved endothelial function are also important. In the future, clinical trials and mechanistic studies might further complement the current knowledge on SGLT2 inhibitors and facilitate to translate these agents to clinical use. Here, we review these mechanisms of SGLT2 inhibitors with an emphasis on kidney protective effects.

Risk Factors Analysis and Management of Cardiometabolic-Based Chronic Disease in Low- and Middle-Income Countries

The epidemic of obesity or adiposity-based chronic diseases presents a significant challenge with the rising prevalence of morbidities and mortality due to atherosclerotic cardiovascular diseases (ASCVD), especially in low- and middle-income countries (LMIC). The underlying pathophysiology of metabolic inflexibility is a common thread linking insulin resistance to cardiometabolic-based chronic disease (CMBCD), including dysglycemia, hypertension, and dyslipidemia progressing to downstream ASCVD events. The complex CMBCD paradigm in the LMIC population within the socio-economic and cultural context highlights considerable heterogeneity of disease predisposition, clinical patterns, and socio-medical needs. This review intends to summarize the current knowledge of CMBCD. We describe recently established or emerging trends for managing risk factors, assessment tools for evaluating ASCVD risk, and various pharmacological and non-pharmacological measures particularly relevant for LMICs. A CMBCD model positions insulin resistance and β-cell dysfunction at the summit of the disease spectrum may improve outcomes at a lower cost in LMICs. Despite identifying multiple pathophysiologic disturbances constituting CMBCD, a large percentage of the patient at risk for ASCVD remains undefined. Targeting dysglycemia, dyslipidemia, and hypertension using antihypertensive, statins, anti-glycemic, and antiplatelet agents has reduced the incidence of ASCVD. Thus, primordial prevention targeting pathophysiological changes that cause abnormalities in adiposity and primary prevention by detecting and managing risk factors remains the foundation for CMBCD management. Therefore, targeting pathways that address mitochondrial dysfunction would exert a beneficial effect on metabolic inflexibility that may potentially correct insulin resistance, β cell dysfunction and, consequently, would be therapeutically effective across the entire continuum of CMBCD.

Do sodium-glucose co-transporter-2 inhibitors increase plasma glucagon by direct actions on the alpha cell? And does the increase matter for the associated increase in endogenous glucose production?

Sodium-glucose co-transporter-2 inhibitors (SGLT2is) lower blood glucose and are used for treatment of type 2 diabetes. However, SGLT2is have been associated with increases in endogenous glucose production (EGP) by mechanisms that have been proposed to result from SGLT2i-mediated increases in circulating glucagon concentrations, but the relative importance of this effect is debated, and mechanisms possibly coupling SGLT2is to increased plasma glucagon are unclear. A direct effect on alpha-cell activity has been proposed, but data on alpha-cell SGLT2 expression are inconsistent, and studies investigating the direct effects of SGLT2 inhibition on glucagon secretion are conflicting. By contrast, alpha-cell sodium-glucose co-transporter-1 (SGLT1) expression has been found more consistently and appears to be more prominent, pointing to an underappreciated role for this transporter. Nevertheless, the selectivity of most SGLT2is does not support interference with SGLT1 during therapy. Paracrine effects mediated by secretion of glucagonotropic/static molecules from beta and/or delta cells have also been suggested to be involved in SGLT2i-induced increase in plasma glucagon, but studies are few and arrive at different conclusions. It is also possible that the effect on glucagon is secondary to drug-induced increases in urinary glucose excretion and lowering of blood glucose, as shown in experiments with glucose clamping where SGLT2i-associated increases in plasma glucagon are prevented. However, regardless of the mechanisms involved, the current balance of evidence does not support that SGLT2 plays a crucial role for alpha-cell physiology or that SGLT2i-induced glucagon secretion is important for the associated increased EGP, particularly because the increase in EGP occurs before any rise in plasma glucagon.

Glucagon-like peptide-1 receptor agonists and sodium-glucose cotransporter 2 inhibitors for diabetes after solid organ transplantation

Post-transplant diabetes mellitus (PTDM) is a common complication of solid organ transplantation and a major cause of increased morbidity and mortality. Additionally, solid organ transplant patients may have pre-existent type 2 diabetes mellitus (T2DM). While insulin is the treatment of choice for hyperglycemia in the first weeks after transplantation, there is no preferred first line agent for long-term management of PTDM or pre-existent T2DM. Glucagon-like peptide-1 receptor agonists (GLP-1RA) and sodium-glucose cotransporter 2 (SGLT2) inhibitors improve glycemic control, lower body weight, and blood pressure, are recommended after lifestyle and metformin as initial therapy for diabetic patients with cardiovascular or kidney comorbidities regarding their cardiorenal benefits. Furthermore, the mechanisms of action of GLP-1RA may counteract some of the driving forces for PTDM, as calcineurin-induced β cell toxicity as per preclinical data, and improve obesity. However, their use in the treatment of PTDM is currently limited by a paucity of data. Retrospective observational and small exploratory studies suggest that GLP-1RA effectively improve glycemic control and induce weight loss in patients with PTDM without interacting with commonly used immunosuppressive agents, although randomized-controlled clinical trials are required to confirm their safety and efficacy. In this narrative review, we evaluate the risk factors and pathogenesis of PTDM and compare the potential roles of GLP-1RA and SGLT2 inhibitors in PTDM prevention and management as well as in pre-existent T2DM, and providing a roadmap for evidence generation on newer antidiabetic drugs for solid organ transplantation.

A decrease in plasma glucose levels is required for increased endogenous glucose production with a single administration of a sodium-glucose co-transporter-2 inhibitor tofogliflozin

AIM

To investigate whether changes in endogenous glucose production (EGP) and insulin and glucagon levels are elicited by the decrease in plasma glucose (PG) levels induced by the sodium-glucose co-transporter-2 (SGLT2) inhibitor tofogliflozin.

MATERIALS AND METHODS

We evaluated EGP in 12 Japanese patients with type 2 diabetes under the conditions of no drugs administered (CON), single administration of the SGLT2 inhibitor tofogliflozin (TOF), and single administration of TOF with adjustment of PG levels with exogenous glucose infusion to mimic changes in PG levels observed with CON (TOF + G). We evaluated changes in EGP and levels of C-peptide and glucagon from baseline to 180 minutes after drug administration.

RESULTS

Endogenous glucose production decreased in the CON (-0.22 ± 0.11 mg/kg·min) and TOF + G experiments (-0.31 ± 0.24 mg/kg·min), but not in the TOF experiment (+0.08 ± 0.19 mg/kg·min). The decrease in C-peptide was significantly greater in the TOF experiment (-0.11 ± 0.06 nmol/L) than in the CON (-0.03 ± 0.06 nmol/L) and the TOF + G experiments (-0.01 ± 0.11 nmol/L), while the increase in glucagon was significantly greater in the TOF experiment (+11.1 ± 6.3 pmol/L), but not in the TOF + G experiment (+8.6 ± 7.6 pmol/L) compared to the CON experiment (+5.1 ± 4.3 pmol/L).

CONCLUSIONS

These results indicate that the decrease in PG levels induced by SGLT2 inhibitor administration is required for the increase in EGP and decrease in insulin secretion.

Type 2 diabetes subgroups and potential medication strategies in relation to effects on insulin resistance and beta-cell function: A step toward personalised diabetes treatment?

Background

Type 2 diabetes is a syndrome defined by hyperglycaemia that is the result of various degrees of pancreatic β-cell failure and reduced insulin sensitivity. Although diabetes can be caused by multiple metabolic dysfunctions, most patients are defined as having either type 1 or type 2 diabetes. Recently, Ahlqvist and colleagues proposed a new method of classifying patients with adult-onset diabetes, considering the heterogenous metabolic phenotype of the disease. This new classification system could be useful for more personalised treatment based on the underlying metabolic disruption of the disease, although to date no prospective intervention studies have generated data to support such a claim.

Scope of Review

In this review, we first provide a short overview of the phenotype and pathogenesis of type 2 diabetes and discuss the current and new classification systems. We then review the effects of different anti-diabetic medication classes on insulin sensitivity and β-cell function and discuss future treatment strategies based on the subgroups proposed by Ahlqvist et al.

Major Conclusions

The proposed novel type 2 diabetes subgroups provide an interesting concept that could lead to a better understanding of the pathophysiology of the broad group of type 2 diabetes, paving the way for personalised treatment choices based on understanding the root cause of the disease. We conclude that the novel subgroups of adult-onset diabetes would benefit from anti-diabetic medications that take into account the main pathophysiology of the disease and thereby prevent end-organ damage. However, we are only beginning to address the personalised treatment of type 2 diabetes, and studies investigating the effects of current and novel drugs in subgroups with different metabolic phenotypes are needed to develop personalised treatment of the syndrome

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Novel subgroups of type 2 diabetes provide a concept that could lead to a better understanding of its pathophysiology.

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Treatment strategies would benefit from anti-diabetic medications that influence the main pathophysiology of diabetes.

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Here, we review different anti-diabetic medications classes affecting insulin sensitivity and β-cell function.

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We suggest that future treatment strategies could benefit by taking into account subgroups provided by Ahlqvist et al.

Increase in endogenous glucose production with SGLT2 inhibition is attenuated in individuals who underwent kidney transplantation and bilateral native nephrectomy

AIMS/HYPOTHESIS

The glucosuria induced by sodium-glucose cotransporter 2 (SGLT2) inhibition stimulates endogenous (hepatic) glucose production (EGP), blunting the decline in HbA_1c. We hypothesised that, in response to glucosuria, a renal signal is generated and stimulates EGP. To examine the effect of acute administration of SGLT2 inhibitors on EGP, we studied non-diabetic individuals who had undergone renal transplant with and without removal of native kidneys.

METHODS

This was a parallel, randomised, double-blind, placebo-controlled, single-centre study, designed to evaluate the effect of a single dose of dapagliflozin or placebo on EGP determined by stable-tracer technique. We recruited non-diabetic individuals who were 30-65 years old, with a BMI of 25-35 kg/m² and stable body weight (±2 kg) over the preceding 3 months, and HbA_1c <42 mmol/mol (6.0%). Participants had undergone renal transplant with and without removal of native kidneys and were on a stable dose of immunosuppressive medications. Participants received a single dose of dapagliflozin 10 mg or placebo on two separate days, at a 5- to 14-day interval, according to randomisation performed by our hospital pharmacy, which provided dapagliflozin and matching placebo, packaged in bulk bottles that were sequentially numbered. Both participants and investigators were blinded to group assignment.

RESULTS

Twenty non-diabetic renal transplant patients (ten with residual native kidneys, ten with bilateral nephrectomy) participated in the study. Dapagliflozin induced greater glucosuria in individuals with residual native kidneys vs nephrectomised individuals (8.6 ± 1.1 vs 5.5 ± 0.5 g/6 h; p = 0.02; data not shown). During the 6 h study period, plasma glucose decreased only slightly and similarly in both groups, with no difference compared with placebo (data not shown). Following administration of placebo, there was a progressive time-related decline in EGP that was similar in both nephrectomised individuals and individuals with residual native kidneys. Following dapagliflozin administration, EGP declined in both groups, but the differences between the decrement in EGP with dapagliflozin and placebo in the group with bilateral nephrectomy (Δ = 1.11 ± 0.72 μmol min^-1 kg^-1) was significantly lower (p = 0.03) than in the residual native kidney group (Δ = 2.56 ± 0.33 μmol min^-1 kg^-1). In the population treated with dapagliflozin, urinary glucose excretion was correlated with EGP (r = 0.34, p < 0.05). Plasma insulin, C-peptide, glucagon, prehepatic insulin:glucagon ratio, lactate, alanine and pyruvate concentrations were similar following placebo and dapagliflozin treatment. β-Hydroxybutyrate increased with dapagliflozin treatment in the residual native kidney group, while a small increase was observed only at 360 min in the nephrectomy group. Plasma adrenaline (epinephrine) did not change after dapagliflozin and placebo treatment in either group. Following dapagliflozin administration, plasma noradrenaline (norepinephrine) increased slightly in the residual native kidney group and decreased in the nephrectomy group.

CONCLUSIONS/INTERPRETATION

In nephrectomised individuals, the hepatic compensatory response to acute SGLT2 inhibitor-induced glucosuria was attenuated, as compared with individuals with residual native kidneys, suggesting that SGLT2 inhibitor-mediated stimulation of hepatic glucose production via efferent renal nerves occurs in an attempt to compensate for the urinary glucose loss (i.e. a renal-hepatic axis).

TRIAL REGISTRATION

ClinicalTrials.gov NCT03168295 FUNDING: This protocol was supported by Qatar National Research Fund (QNRF) Award No. NPRP 8-311-3-062 and NIH grant DK024092-38. Graphical abstract.

Sodium-glucose cotransporter-2 inhibitors: Understanding the mechanisms for therapeutic promise and persisting risks

In a healthy person, the kidney filters nearly 200 g of glucose per day, almost all of which is reabsorbed. The primary transporter responsible for renal glucose reabsorption is sodium-glucose cotransporter-2 (SGLT2). Based on the impact of SGLT2 to prevent renal glucose wasting, SGLT2 inhibitors have been developed to treat diabetes and are the newest class of glucose-lowering agents approved in the United States. By inhibiting glucose reabsorption in the proximal tubule, these agents promote glycosuria, thereby reducing blood glucose concentrations and often resulting in modest weight loss. Recent work in humans and rodents has demonstrated that the clinical utility of these agents may not be limited to diabetes management: SGLT2 inhibitors have also shown therapeutic promise in improving outcomes in heart failure, atrial fibrillation, and, in preclinical studies, certain cancers. Unfortunately, these benefits are not without risk: SGLT2 inhibitors predispose to euglycemic ketoacidosis in those with type 2 diabetes and, largely for this reason, are not approved to treat type 1 diabetes. The mechanism for each of the beneficial and harmful effects of SGLT2 inhibitors-with the exception of their effect to lower plasma glucose concentrations-is an area of active investigation. In this review, we discuss the mechanisms by which these drugs cause euglycemic ketoacidosis and hyperglucagonemia and stimulate hepatic gluconeogenesis as well as their beneficial effects in cardiovascular disease and cancer. In so doing, we aim to highlight the crucial role for selecting patients for SGLT2 inhibitor therapy and highlight several crucial questions that remain unanswered.