Endogenous Glucose Production and Hormonal Changes in Response to Canagliflozin and Liraglutide Combination Therapy

β-Cell Function, Incretin Effect, and Glucose Kinetics in Response to a Mixed Meal in Patients With Type 2 Diabetes Treated With Dapagliflozin Plus Saxagliptin

OBJECTIVE

To explore the complementary effects of a combination of dipeptidyl peptidase 4 and sodium-glucose cotransporter 2 inhibitors added to metformin on hormonal and metabolic responses to meal ingestion.

RESEARCH DESIGN AND METHODS

Forty-five patients (age 58 ± 8 years; HbA1c 58 ± 6 mmol/mol; BMI 30.7 ± 3.2 kg/m2) with type 2 diabetes uncontrolled with metformin were evaluated at baseline and 3 and 28 days after 5 mg saxagliptin (SAXA), 10 mg dapagliflozin (DAPA), or 5 mg saxagliptin plus 10 mg dapagliflozin (SAXA+DAPA) using a mixed-meal tolerance test (MMTT) spiked with dual-tracer glucose to assess glucose metabolism, insulin secretion, and sensitivity.

RESULTS

At day 3, fasting and mean MMTT glucose levels were lower with SAXA+DAPA (-31.1 ± 1.6 and -91.5 ± 12.4 mg/dL) than with SAXA (-7.1 ± 2.1 and -53 ± 10.5 mg/dL) or DAPA (-17.0 ± 1.1 and -42.6 ± 10.0 mg/dL, respectively; P < 0.001). Insulin secretion rate (SAXA+DAPA +75%; SAXA +11%; DAPA +3%) and insulin sensitivity (+2.2 ± 1.7, +0.4 ± 0.7, and +0.4 ± 0.4 mg ⋅ kg-1⋅ min-1, respectively) improved with SAXA+DAPA (P < 0.007). Mean glucagon-like peptide 1 (GLP-1) was higher with SAXA+DAPA than with SAXA or DAPA. Fasting glucagon increased with DAPA and SAXA+DAPA but not with SAXA. Fasting endogenous glucose production (EGP) increased with SAXA+DAPA and DAPA. During MMTT, EGP suppression was greater (48%) with SAXA+DAPA (vs. SAXA 44%; P = 0.02 or DAPA 34%; P = 0.2). Metabolic clearance rate of glucose (MCRglu) increased more with SAXA+DAPA. At week 4, insulin secretion rate, β-cell glucose sensitivity, and insulin sensitivity had further increased in the SAXA+DAPA group (P = 0.02), with no additional changes in GLP-1, glucagon, fasting or MMTT EGP, or MCRglu.

CONCLUSIONS

SAXA+DAPA provided superior glycemic control compared with DAPA or SAXA, with improved β-cell function, insulin sensitivity, GLP-1 availability, and glucose clearance.

Effect of Dapagliflozin on Renal and Hepatic Glucose Kinetics in T2D and NGT Subjects

Acute and chronic sodium-glucose cotransporter 2 (SGLT-2) inhibition increases endogenous glucose production (EGP). However, the organ-liver versus kidney-responsible for the increase in EGP has not been identified. In this study, 20 subjects with type 2 diabetes (T2D) and 12 subjects with normal glucose tolerance (NGT) received [3-3H]glucose infusion (to measure total EGP) combined with arterial and renal vein catheterization and para-aminohippuric acid infusion for determination of renal blood flow. Total EGP, net renal arteriovenous balance, and renal glucose production were measured before and 4 h after dapagliflozin (DAPA) and placebo administration. Following DAPA, EGP increased in both T2D and NGT from baseline to 240 min, while there was a significant time-related decrease after placebo in T2D. Renal glucose production at baseline was <5% of basal EGP in both groups and did not change significantly following DAPA in NGT or T2D. Renal glucose uptake (sum of tissue glucose uptake plus glucosuria) increased in both T2D and NGT following DAPA (P < 0.05 vs. placebo). The increase in renal glucose uptake was entirely explained by the increase in glucosuria. A single dose of DAPA significantly increased EGP, which primarily is explained by an increase in hepatic glucose production, establishing the existence of a novel renal-hepatic axis.

ARTICLE HIGHLIGHTS

Glycemia and Gluconeogenesis With Metformin and Liraglutide: A Randomized Trial in Youth-onset Type 2 Diabetes

OBJECTIVE

Elevated rates of gluconeogenesis are an early pathogenic feature of youth-onset type 2 diabetes (Y-T2D), but targeted first-line therapies are suboptimal, especially in African American (AA) youth. We evaluated glucose-lowering mechanisms of metformin and liraglutide by measuring rates of gluconeogenesis and β-cell function after therapy in AA Y-T2D.

METHODS

In this parallel randomized clinical trial, 22 youth with Y-T2D-age 15.3 ± 2.1 years (mean ± SD), 68% female, body mass index (BMI) 40.1 ± 7.9 kg/m2, duration of diagnosis 1.8 ± 1.3 years-were randomized to metformin alone (Met) or metformin + liraglutide (Lira) (Met + Lira) and evaluated before and after 12 weeks. Stable isotope tracers were used to measure gluconeogenesis [2H2O] and glucose production [6,6-2H2]glucose after an overnight fast and during a continuous meal. β-cell function (sigma) and whole-body insulin sensitivity (mSI) were assessed during a frequently sampled 2-hour oral glucose tolerance test.

RESULTS

At baseline, gluconeogenesis, glucose production, and fasting and 2-hour glucose were comparable in both groups, though Met + Lira had higher hemoglobin A1C. Met + Lira had a greater decrease from baseline in fasting glucose (-2.0 ± 1.3 vs -0.6 ± 0.9 mmol/L, P = .008) and a greater increase in sigma (0.72 ± 0.68 vs -0.05 ± 0.71, P = .03). The change in fractional gluconeogenesis was similar between groups (Met + Lira: -0.36 ± 9.4 vs Met: 0.04 ± 12.3%, P = .9), and there were no changes in prandial gluconeogenesis or mSI. Increased glucose clearance in both groups was related to sigma (r = 0.63, P = .003) but not gluconeogenesis or mSI.

CONCLUSION

Among Y-T2D, metformin with or without liraglutide improved glycemia but did not suppress high rates of gluconeogenesis. Novel therapies that will enhance β-cell function and target the elevated rates of gluconeogenesis in Y-T2D are needed.

Role of GLP-1 Receptor Agonist in Diabetic Cardio-renal Disorder: Recent Updates of Clinical and Pre-clinical Evidence

Cardiovascular complications and renal disease is the growing cause of mortality in patients with diabetes. The subversive complications of diabetes such as hyperglycemia, hyperlipidemia and insulin resistance lead to an increase in the risk of myocardial infarction (MI), stroke, heart failure (HF) as well as chronic kidney disease (CKD). Among the commercially available anti-hyperglycemic agents, incretin-based medications appear to be safe and effective in the treatment of type 2 diabetes mellitus (T2DM) and associated cardiovascular and renal disease. Glucagon-like peptide 1 receptor agonists (GLP-1RAs) have been shown to be fruitful in reducing HbA1c, blood glucose, lipid profile, and body weight in diabetic patients. Several preclinical and clinical studies revealed the safety, efficacy, and preventive advantages of GLP-1RAs against diabetes- induced cardiovascular and kidney disease. Data from cardio-renal outcome trials had highlighted that GLP-1RAs protected people with established CKD from significant cardiovascular disease, lowered the likelihood of hospitalization for heart failure (HHF), and lowered all-cause mortality. They also had a positive effect on people with end-stage renal disease (ESRD) and CKD. Beside clinical outcomes, GLP-1RAs reduced oxidative stress, inflammation, fibrosis, and improved lipid profile pre-clinically in diabetic models of cardiomyopathy and nephropathy that demonstrated the cardio-protective and reno-protective effect of GLP-1RAs. In this review, we have focused on the recent clinical and preclinical outcomes of GLP-1RAs as cardio-protective and reno-protective agents as GLP-1RAs medications have been demonstrated to be more effective in treating T2DM and diabetes-induced cardiovascular and renal disease than currently available treatments in clinics, without inducing hypoglycemia or weight gain.

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.

Short-term effects of canagliflozin on glucose and insulin responses in insulin dysregulated horses: A randomized, placebo-controlled, double-blind, study

BACKGROUND

Decreasing hyperinsulinemia is crucial in preventing laminitis in insulin dysregulated (ID) horses. Complementary pharmacological treatments that efficiently decrease postprandial hyperinsulinemia in ID horses are needed.

OBJECTIVES

Compare short-term effects of canagliflozin vs placebo on glucose and insulin responses to an oral sugar test (OST) as well as the effects on body weight and triglyceride concentrations in horses with ID.

ANIMALS

Sixteen privately-owned ID horses.

METHODS

A single-center, randomized, double-blind, placebo-controlled, parallel design study. The horses were randomized (ratio 1:1) to either once daily PO treatment with 0.6 mg/kg canagliflozin or placebo. The study consisted of an initial 3-day period for obtaining baseline data, a 3-week double-blind treatment period at home, and a 3-day follow-up period similar to the initial baseline period but with continued double-blind treatment. Horses were subjected to an 8-sample OST in the morning of the third day on both visits.

RESULTS

Maximal geometric least square (LS) mean insulin concentration (95% confidence interval [CI]) during the OST decreased after 3 weeks of canagliflozin treatment compared with placebo (83.2; 55.4-125.0 vs 215.2; 143.2-323.2 μIU/mL). The geometric LS mean insulin response (insulin AUC0-180 ) for canagliflozin-treated horses was >66% lower compared with placebo. Least square mean body weight decreased by 11.1 (4-18.1) kg and LS mean triglyceride concentrations increased by 0.99 (0.47-1.5) mmol/L with canagliflozin treatment.

CONCLUSIONS AND CLINICAL IMPORTANCE

Canagliflozin is a promising drug for treatment of ID horses that requires future studies.

Glucagon and Its Receptors in the Mammalian Heart

Glucagon exerts effects on the mammalian heart. These effects include alterations in the force of contraction, beating rate, and changes in the cardiac conduction system axis. The cardiac effects of glucagon vary according to species, region, age, and concomitant disease. Depending on the species and region studied, the contractile effects of glucagon can be robust, modest, or even absent. Glucagon is detected in the mammalian heart and might act with an autocrine or paracrine effect on the cardiac glucagon receptors. The glucagon levels in the blood and glucagon receptor levels in the heart can change with disease or simultaneous drug application. Glucagon might signal via the glucagon receptors but, albeit less potently, glucagon might also signal via glucagon-like-peptide-1-receptors (GLP1-receptors). Glucagon receptors signal in a species- and region-dependent fashion. Small molecules or antibodies act as antagonists to glucagon receptors, which may become an additional treatment option for diabetes mellitus. Hence, a novel review of the role of glucagon and the glucagon receptors in the mammalian heart, with an eye on the mouse and human heart, appears relevant. Mouse hearts are addressed here because they can be easily genetically modified to generate mice that may serve as models for better studying the human glucagon receptor.

Distinct Mechanisms Responsible for the Increase in Glucose Production and Ketone Formation Caused by Empagliflozin in T2DM Patients

OBJECTIVE

To examine the mechanisms responsible for the increase in glucose and ketone production caused by empagliflozin in patients with type 2 diabetes mellitus (T2DM).

RESEARCH DESIGN AND METHODS

Twelve subjects with T2DM participated in two studies performed in random order. In study 1, endogenous glucose production (EGP) was measured with 8-h infusion of 6,6,D2-glucose. Three hours after the start of 6,6,D2-glucose infusion, subjects ingested 25 mg empagliflozin (n = 8) or placebo (n = 4), and norepinephrine (NE) turnover was measured before and after empagliflozin ingestion with 3H-NE infusion. Study 2 was similar to study 1 but performed under pancreatic clamp conditions.

RESULTS

When empagliflozin was ingested under fasting conditions, EGP increased by 31% in association with a decrease in plasma glucose (-34 mg/dL) and insulin (-52%) concentrations and increases in plasma glucagon (+19%), free fatty acid (FFA) (+29%), and β-hydroxybutyrate (+48%) concentrations. When empagliflozin was ingested under pancreatic clamp conditions, plasma insulin and glucagon concentrations remained unchanged, and the increase in plasma FFA and ketone concentrations was completely blocked, while the increase in EGP persisted. Total-body NE turnover rate was greater in subjects receiving empagliflozin (+67%) compared with placebo under both fasting and pancreatic clamp conditions. No difference in plasma NE concentration was observed in either study.

CONCLUSIONS

The decrease in plasma insulin and increase in plasma glucagon concentration caused by empagliflozin is responsible for the increase in plasma FFA concentration and ketone production. The increase in EGP caused by empagliflozin is independent of the change in plasma insulin or glucagon concentrations and is likely explained by the increase in NE turnover.

New insights into cellular links between sodium-glucose cotransporter-2 inhibitors and ketogenesis

Sodium-glucose cotransporter-2 inhibitors (SGLT2is) are a newly developed class of highly effective antidiabetic therapies that normalize hyperglycemia via urinary glucose excretion. However, they may be accompanied by certain side effects that negatively impact their therapeutic benefits. SGLT2is induce a metabolic shift from glucose to fatty acids and thus increase lipolysis which, in turn, induces ketogenesis. The complete pathways linking SGLT2is to ketoacidosis have not yet been fully elucidated, though much is now known. Therefore, in this mechanistic study, we present the current knowledge and shed light upon the possible cellular pathways involved. A deeper understanding of the possible links between SGLT2is and ketogenesis could help to prevent adverse side effects in diabetic patients treated with these drugs.

Metabolic and cardiovascular benefits with combination therapy of SGLT-2 inhibitors and GLP-1 receptor agonists in type 2 diabetes

Both GLP-1 receptor agonists (GLP-1RA) and SGLT-2 inhibitors (SGLT-2I) are newer classes of anti-diabetic agents that lower HbA1c moderately and decrease body weight and systolic blood pressure (SBP) modestly. Combination therapy with GLP-1RA plus SGLT-2I have shown a greater reduction in HbA1c, body weight, and SBP compared to either agent alone without any significant increase in hypoglycemia or other side effects. Since several agents from each class of these drugs have shown an improvement in cardiovascular (CV) and renal outcomes in their respective cardiovascular outcome trials (CVOT), combination therapy is theoretically expected to have additional CV and renal benefits. In this comprehensive opinion review, we found HbA1c lowering with GLP-1RA plus SGLT-2I to be less than additive compared to the sum of HbA1c lowering with either agent alone, although body weight lowering was nearly additive and the SBP lowering was more than additive. Our additional meta-analysis of CV outcomes with GLP-1RA plus SGLT-2I combination therapy from the pooled data of five CVOT found a similar reduction in three-point major adverse cardiovascular events compared to GLP-1RA or SGLT-2I alone, against placebo. Interestingly, a greater benefit in reduction of heart failure hospitalization with GLP-1RA plus SGLT-2I combination therapy was noted in the pooled meta-analysis of two randomized controlled trials. Future adequately powered trials can confirm whether additional CV or renal benefit is truly exerted by GLP-1RA plus SGLT-2I combination therapy.

Dapagliflozin Impairs the Suppression of Endogenous Glucose Production in Type 2 Diabetes Following Oral Glucose

OBJECTIVE

To examine the effect of SGLT2 inhibitors (SGLT2i) on endogenous glucose production (EGP) in patients with type 2 diabetes after an oral glucose load.

RESEARCH DESIGN AND METHODS

Forty-eight patients with type 2 diabetes received an 8-h [3-3H]-glucose infusion (protocol I) to assess EGP response to: 1) dapagliflozin (DAPA), 10 mg; 2) exenatide (EXE), 5 μg s.c.; 3) DAPA/EXE; and 4) placebo (PCB). After 2 weeks (protocol II), patients were restudied with a 5-h double-tracer (i.v. [3-3H]-glucose and oral [1-14C]-glucose) oral glucose tolerance test (OGTT) preceded by PCB, DAPA, EXE, or DAPA/EXE.

RESULTS

Protocol I: EGP decreased (P < 0.01) with PCB (2.16 ± 0.15 to 1.57 ± 0.08 mg/kg/min) and EXE (2.13 ± 0.16 to 1.58 ± 0.03) and remained unchanged (P = NS) with DAPA (2.04 ± 0.17 vs. 1.94 ± 0.18) and DAPA/EXE (2.13 ± 0.10 vs. 2.09 ± 0.03). During OGTT, EGP decreased (P < 0.01) with PCB (2.30 ± 0.05 to. 1.45 ± 0.06 mg/kg/min) and EXE (2.53 ± 0.08 to 1.36 ± 0.06); with DAPA (2.20 ± 0.04 vs. 1.71 ± 0.07) and DAPA/EXE (2.48 ± 0.05 vs. 1.64 ± 0.07), the decrease in EGP was attenuated (both P < 0.05). During OGTT, the insulin/glucagon (INS/GCN) ratio increased in PCB (0.26 ± 0.03 vs. 0.71 ± 0.06 μU/mL per pg/mL), whereas in DAPA (0.26 ± 0.02 to 0.50 ± 0.04), the increase was blunted (P < 0.05). In EXE, INS/GCN increased significantly (0.32 ± 0.03 to 1.31 ± 0.08) and was attenuated in DAPA/EXE (0.32 ± 0.03 vs. 0.78 ± 0.08) (P < 0.01).

CONCLUSIONS

These findings provide novel evidence that the increase in EGP induced by SGLT2i is present during an oral glucose load. The fact that stimulation of EGP occurs despite elevated plasma insulin and glucagon suggests that additional factors must be involved.

Peptides in the regulation of glucagon secretion

Glucose homeostasis is maintained by the glucoregulatory hormones, glucagon, insulin and somatostatin, secreted from the islets of Langerhans. Glucagon is the body's most important anti-hypoglycemic hormone, mobilizing glucose from glycogen stores in the liver in response to fasting, thus maintaining plasma glucose levels within healthy limits. Glucagon secretion is regulated by both circulating nutrients, hormones and neuronal inputs. Hormones that may regulate glucagon secretion include locally produced insulin and somatostatin, but also urocortin-3, amylin and pancreatic polypeptide, and from outside the pancreas glucagon-like peptide-1 and 2, peptide tyrosine tyrosine and oxyntomodulin, glucose-dependent insulinotropic polypeptide, neurotensin and ghrelin, as well as the hypothalamic hormones arginine-vasopressin and oxytocin, and calcitonin from the thyroid. Each of these hormones have distinct effects, ranging from regulating blood glucose, to regulating appetite, stomach emptying rate and intestinal motility, which makes them interesting targets for treating metabolic diseases. Awareness regarding the potential effects of the hormones on glucagon secretion is important since secretory abnormalities could manifest as hyperglycemia or even lethal hypoglycemia. Here, we review the effects of each individual hormone on glucagon secretion, their interplay, and how treatments aimed at modulating the plasma levels of these hormones may also influence glucagon secretion and glycemic control.

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.

Estimating Increased EGP During Stress Response in Critically Ill Patients

BACKGROUND

Stress-induced hyperglycemia is frequently experienced by critically ill patients and the use of glycemic control (GC) has been shown to improve patient outcomes. For model-based approaches to GC, it is important to understand and quantify model parameter assumptions. This study explores endogenous glucose production (EGP) and the use of a population-based parameter value in the intensive care unit context.

METHOD

Hourly insulin sensitivity (SI) was fit to clinical data from 145 patients on the Specialized Relative Insulin and Nutrition Titration GC protocol for at least 24 hours. Constraint of SI at a lower bound was used to explore likely EGP variability due to stress response. Minimum EGP was estimated during times when the model SI was constrained, and time and duration of events were examined.

RESULTS

Constrained events occur for 1.6% of patient hours. About 70% of constrained events occur in the first 12 hours and most events (~80%) occur when there is no exogenous nutrition given. Enhanced EGP values ranged from 1.16 mmol/min (current population value) to 2.75 mmol/min, with most being below 1.5 mmol/min (21% increase).

CONCLUSION

The frequency of constrained events is low and the current population value of 1.16 mmol/min is sufficient for more than 98% of patient hours, however, some patients experience significantly raised EGP probably due to an extreme stress response early in patient stay.

SGLT2i increased the plasma fasting glucagon level in patients with diabetes: A meta-analysis

Increased glucagon level was hypothesized to participate in the ketoacidosis associated with sodium-glucose co-transporter 2 inhibitors (SGLT2i) treatment. However, the effect of SGLT2i on glucagon remains controversial. Hence, we conducted this meta-analysis to assess the overall effect of SGLT2i treatment on plasma fasting glucagon level in patients with diabetes. PubMed/MEDLINE, Embase, and Cochrane databases were searched for studies published before August 2020. Clinical trials in patients with type 1 diabetes mellitus and type 2 diabetes mellitus with reports of glucagon changes before and after SGLT2i intervention were included. Eligible trials were analyzed by fixed-effect model, random effect model, and meta-regression analysis accordingly. In total, ten trials were included in this meta-analysis. Compared with the non-SGLT2i treatment group, SGLT2i treatment resulted in increased plasma fasting glucagon levels with significance (WMD, 8.35 pg/ml; 95% CI, 2.17-14.54 pg/ml, P＜0.01) in patients with diabetes mellitus. Besides, when compared with non-SGLT2i control group, the insulin level decreased (WMD, -2.78 μU/ml; 95% CI, -5.11 to -0.46 μU/ml, P = 0.02) and ketone body level increased (WMD, 0.17 mmol/l; 95% CI, 0.09-0.25 mmol/l, P＜0.01) in patients with type 2 diabetes. In conclusion, our result indicated SGLT2i intervention would increase the plasma fasting glucagon level in patients with diabetes mellitus. The increase in plasma fasting glucagon level may be associated with reduced insulin level. The increased glucagon-insulin ratio after the use of SGLT2i may make diabetic patients susceptible to ketosis.

Effect of Dapagliflozin on Urine Metabolome in Patients with Type 2 Diabetes

CONTEXT

Inhibitors of sodium-glucose cotransporters-2 have cardio- and renoprotective properties. However, the underlying mechanisms remain indeterminate.

OBJECTIVE

To evaluate the effect of dapagliflozin on renal metabolism assessed by urine metabolome analysis in patients with type 2 diabetes.

DESIGN

Prospective cohort study.

SETTING

Outpatient diabetes clinic of a tertiary academic center.

PATIENTS

Eighty patients with hemoglobin A1c > 7% on metformin monotherapy were prospectively enrolled.

INTERVENTION

Fifty patients were treated with dapagliflozin for 3 months. To exclude that the changes observed in urine metabolome were merely the result of the improvement in glycemia, 30 patients treated with insulin degludec were used for comparison.

MAIN OUTCOME MEASURE

Changes in urine metabolic profile before and after the administration of dapagliflozin and insulin degludec were assessed by proton-nuclear magnetic resonance spectroscopy.

RESULTS

In multivariate analysis urine metabolome was significantly altered by dapagliflozin (R2X = 0.819, R2Y = 0.627, Q2Y = 0.362, and coefficient of variation analysis of variance, P < 0.001) but not insulin. After dapagliflozin, the urine concentrations of ketone bodies, lactate, branched chain amino acids (P < 0.001), betaine, myo-inositol (P < 0001), and N-methylhydantoin (P < 0.005) were significantly increased. Additionally, the urine levels of alanine, creatine, sarcosine, and citrate were also increased (P < 0001, P <0.0001, and P <0.0005, respectively) whereas anserine decreased (P < 0005).

CONCLUSIONS

Dapagliflozin significantly affects urine metabolome in patients with type 2 diabetes in a glucose lowering-independent way. Most of the observed changes can be considered beneficial and may contribute to the renoprotective properties of dapagliflozin.

Dulaglutide Alone and in Combination with Empagliflozin Attenuate Inflammatory Pathways and Microbiome Dysbiosis in a Non-Diabetic Mouse Model of NASH

Dysregulation of glucose homeostasis plays a major role in the pathogenesis of non-alcoholic steatohepatitis (NASH) as it activates proinflammatory and profibrotic processes. Beneficial effects of antiglycemic treatments such as GLP-1 agonist or SGLT-2 inhibitor on NASH in patients with diabetes have already been investigated. However, their effect on NASH in a non-diabetic setting remains unclear. With this aim, we investigated the effect of long-acting GLP1-agonist dulaglutide and SGLT-2 inhibitor empagliflozin and their combination in a non-diabetic mouse model of NASH. C57BL/6 mice received a high-fat-high-fructose (HFHC) diet with a surplus of cholesterol for 16 weeks. After 12 weeks of diet, mice were treated with either dulaglutide, empagliflozin or their combination. Dulaglutide alone and in combination with empagliflozin led to significant weight loss, improved glucose homeostasis and diminished anti-inflammatory and anti-fibrotic pathways. Combination of dulaglutide and empagliflozin further decreased MoMFLy6C^High and CD4⁺Foxp3⁺ T cells. No beneficial effects for treatment with empagliflozin alone could be shown. While no effect of dulaglutide or its combination with empaglifozin on hepatic steatosis was evident, these data demonstrate distinct anti-inflammatory effects of dulaglutide and their combination with empagliflozin in a non-diabetic background, which could have important implications for further treatment of NASH.

Unexpected Pleiotropic Effects of SGLT2 Inhibitors: Pearls and Pitfalls of This Novel Antidiabetic Class

Sodium-glucose co-transporter 2 (SGLT2) inhibitors facilitate urine glucose excretion by reducing glucose reabsorption, leading to ameliorate glycemic control. While the main characteristics of type 2 diabetes mellitus are insufficient insulin secretion and insulin resistance, SGLT2 inhibitors have some favorable effects on pancreatic β-cell function and insulin sensitivity. SGLT2 inhibitors ameliorate fatty liver and reduce visceral fat mass. Furthermore, it has been noted that SGLT2 inhibitors have cardio-protective and renal protective effects in addition to their glucose-lowering effect. In addition, several kinds of SGLT2 inhibitors are used in patients with type 1 diabetes mellitus as an adjuvant therapy to insulin. Taken together, SGLT2 inhibitors have amazing multifaceted effects that are far beyond prediction like some emerging magical medicine. Thereby, SGLT2 inhibitors are very promising as relatively new anti-diabetic drugs and are being paid attention in various aspects. It is noted, however, that SGLT2 inhibitors have several side effects such as urinary tract infection or genital infection. In addition, we should bear in mind the possibility of diabetic ketoacidosis, especially when we use SGLT2 inhibitors in patients with poor insulin secretory capacity.

Gluconeogenesis, But Not Glycogenolysis, Contributes to the Increase in Endogenous Glucose Production by SGLT-2 Inhibition

OBJECTIVE

Recent studies indicate that sodium-glucose cotransporter 2 (SGLT-2) inhibition increases endogenous glucose production (EGP), potentially counteracting the glucose-lowering potency, and stimulates lipid oxidation and lipolysis. However, the acute effects of SGLT-2 inhibition on hepatic glycogen, lipid, and energy metabolism have not yet been analyzed. We therefore investigated the impact of a single dose of dapagliflozin (D) or placebo (P) on hepatic glycogenolysis, hepatocellular lipid (HCL) content and mitochondrial activity (kATP).

RESEARCH DESIGN AND METHODS

Ten healthy volunteers (control [CON]: age 30 ± 3 years, BMI 24 ± 1 kg/m², HbA_1c 5.2 ± 0.1%) and six patients with type 2 diabetes mellitus (T2DM: age 63 ± 4 years, BMI 28 ± 1.5 kg/m², HbA_1c 6.1 ± 0.5%) were investigated on two study days (CON-P vs. CON-D and T2DM-P vs. T2DM-D). ¹H/¹³C/³¹P MRS was performed before, 90-180 min (MR1), and 300-390 min (MR2) after administration of 10 mg dapagliflozin or placebo. EGP was assessed by tracer dilution techniques.

RESULTS

Compared with CON-P, EGP was higher in CON-D (10.0 ± 0.3 vs. 12.4 ± 0.5 μmol kg^-1 min^-1; P < 0.05) and comparable in T2DM-D and T2DM-P (10.1 ± 0.7 vs. 10.4 ± 0.5 μmol kg^-1 min^-1; P = not significant [n.s.]). A strong correlation of EGP with glucosuria was observed (r = 0.732; P < 0.01). The insulin-to-glucagon ratio was lower after dapagliflozin in CON-D and T2DM-D compared with baseline (P < 0.05). Glycogenolysis did not differ between CON-P and CON-D (-3.28 ± 0.49 vs. -2.53 ± 0.56 μmol kg^-1 min^-1; P = n.s.) or T2DM-P and T2DM-D (-0.74 ± 0.23 vs. -1.21 ± 0.33 μmol kg^-1 min^-1; P = n.s.), whereas gluconeogenesis was higher after dapagliflozin in CON-P compared with CON-D (6.7 ± 0.6 vs. 9.9 ± 0.6 μmol kg^-1 min^-1; P < 0.01) but not in T2DM. No significant changes in HCL and kATP were observed.

CONCLUSIONS

The rise in EGP after SGLT-2 inhibition is due to increased gluconeogenesis, but not glycogenolysis. Changes in glucagon and the insulin-to-glucagon ratio are not associated with an increased hepatic glycogen breakdown. HCL and kATP are not significantly affected by a single dose of dapagliflozin.

Impact of an SGLT2-loss of function mutation on renal architecture, histology, and glucose homeostasis

Inhibitors of sodium/glucose co-transporter 2 (SGLT2) are currently in clinical use for type 2 diabetes (T2D) treatment due to their anti-hyperglycemic effect exerted by the inhibition of glucose reabsorption in the kidney. Inhibition of SGLT2 is associated with improvement of renal outcomes in chronic kidney disease associated with T2D. Our study aimed to describe the renal-specific phenotypic consequences of the SGLT2-loss of function "Jimbee" mutation within the Slc5a2 mouse gene in a non-diabetic/non-obese background. The Jimbee mice displayed reduced body weight, glucosuria, polyuria, polydipsia, and hyperphagia but were normoglycemic, with no signs of baseline insulin resistance or renal dysfunction. Histomorphological analysis of the kidneys revealed a normal architecture and morphology of the renal cortex, but shrinkage of the glomerular and tubular apparatus, including Bowman's space, glomerular tuft, mesangial matrix fraction, and proximal convoluted tubule (PCT). Immunofluorescent analysis of renal sections showed that SGLT2 was absent from the apical membrane of PCT of the Jimbee mice but remnant positive vesicles were detected within the cytosol or at the perinuclear interface. Renal localization and abundance of GLUT1, GLUT2, and SGLT1 were unchanged in the Jimbee genotype. Intriguingly, the mutation did not induce hepatic gluconeogenic gene expression in overnight fasted mice despite a high glucose excretion rate. The Jimbee phenotype is remarkably similar to humans with SLC5A2 mutations and provides a useful model for the study of SGLT2-loss of function effects on renal architecture and physiology, as well as for identifying possible novel roles for the kidneys in glucose homeostasis and metabolic reprogramming.

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.

The Role of Glucagon in the Acute Therapeutic Effects of SGLT2 Inhibition

Sodium-glucose cotransporter 2 inhibitors (SGLT2i) effectively lower plasma glucose (PG) concentration in patients with type 2 diabetes, but studies have suggested that circulating glucagon concentrations and endogenous glucose production (EGP) are increased by SGLT2i, possibly compromising their glucose-lowering ability. To tease out whether and how glucagon may influence the glucose-lowering effect of SGLT2 inhibition, we subjected 12 patients with type 2 diabetes to a randomized, placebo-controlled, double-blinded, crossover, double-dummy study comprising, on 4 separate days, a liquid mixed-meal test preceded by single-dose administration of either 1) placebo, 2) the SGLT2i empagliflozin (25 mg), 3) the glucagon receptor antagonist LY2409021 (300 mg), or 4) the combination empagliflozin + LY2409021. Empagliflozin and LY2409021 individually lowered fasting PG compared with placebo, and the combination further decreased fasting PG. Previous findings of increased glucagon concentrations and EGP during acute administration of SGLT2i were not replicated in this study. Empagliflozin reduced postprandial PG through increased urinary glucose excretion. LY2409021 reduced EGP significantly but gave rise to a paradoxical increase in postprandial PG excursion, which was annulled by empagliflozin during their combination (empagliflozin + LY2409021). In conclusion, our findings do not support that an SGLT2i-induced glucagonotropic effect is of importance for the glucose-lowering property of SGLT2 inhibition.

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.

Improved Beta Cell Glucose Sensitivity Plays Predominant Role in the Decrease in HbA1c with Cana and Lira in T2DM

AIM

To examine the effect of combination therapy with canagliflozin plus liraglutide versus each agent alone on beta cell function in type 2 diabetes mellitus (T2DM) patients.

RESEARCH DESIGN AND METHODS

A total of 45 poorly controlled (HbA1c = 7%-11%) T2DM patients received an oral glucose tolerance test (OGTT) before and after 16 weeks of treatment with: (i) liraglutide (LIRA); (ii) canagliflozin (CANA); (iii) liraglutide plus canagliflozin (CANA/LIRA).

RESULTS

Both liraglutide and canagliflozin significantly lowered HbA1c with no significant additive effect of the combination on HbA1c (0.89%, 1.43%, and 1.67% respectively). Insulin secretion during the OGTT, measured with (∆C-Pep/∆G)0-120, increased in the 3 groups (from 0.30 ± 0.06 to 0.48 ± 0.10; 0.29 ± 0.05 to 0.98 ± 0.23; and 0.24 ± 0.06 to 1.09 ± 0.12 in subjects receiving CANA, LIRA and CANA/LIRA respectively; P = 0.02 for CANA vs LIRA, P < 0.0001, CANA/LIRA vs CANA), and the increase in insulin secretion was associated with an increase in beta cell glucose sensitivity (29 ± 5 to 55 ± 11; 33 ± 6 to 101 ± 16; and 28 ± 6 to 112 ± 12, respectively; P = 0.01 for CANA vs LIRA, P < 0.0001, CANA/LIRA vs CANA). No significant difference in the increase in insulin secretion or beta cell glucose sensitivity was observed between subjects in LIRA or CANA/LIRA groups. The decrease in HbA1c strongly and inversely correlated with the increase in beta cell glucose sensitivity (r = 0.71, P < 0.001). In multivariate regression model, improved beta cell glucose sensitivity was the strongest predictor of HbA1c decrease with each therapy.

CONCLUSION

Improved beta cell glucose sensitivity with canagliflozin monotherapy and liraglutide monotherapy or in combination is major factor responsible for the HbA1c decrease. Canagliflozin failed to produce an additive effect to improve beta cell glucose sensitivity above that observed with liraglutide.

Clinical Parameters, Fuel Oxidation, and Glucose Kinetics in Patients With Type 2 Diabetes Treated With Dapagliflozin Plus Saxagliptin

OBJECTIVE

To examine the mechanisms responsible for improved glycemia with combined sodium-glucose cotransporter 2 inhibitor (SGLT2i) plus dipeptidyl peptidase 4 inhibitor therapy in type 2 diabetes.

RESEARCH DESIGN AND METHODS

Fifty-six patients (HbA_1c 8.9 ± 0.2% [74 ± 2 mmol/mol]) were randomized to dapagliflozin (DAPA) 10 mg, DAPA/saxagliptin (SAXA) 10/5 mg, or placebo (PCB) for 16 weeks. Basal endogenous glucose production (EGP) (3-³H-glucose), urinary glucose excretion, glucose/lipid oxidation, HbA_1c, and substrate/hormone levels were determined before treatment (Pre-Tx) and after treatment (Post-Tx).

RESULTS

At week 16, HbA_1c decrease was greater (P < 0.05) in DAPA/SAXA (-2.0 ± 0.3%) vs. DAPA (-1.4 ± 0.2%) and greater than PCB (0.2 ± 0.2%). Day 1 of drug administration, EGP (∼2.40 mg/kg/min) decreased by -0.44 ± 0.09 mg/kg/min in PCB (P < 0.05) but only by -0.21 ± 0.02 mg/kg/min in DAPA and DAPA/SAXA (P < 0.05 vs. PCB). At week 16, EGP increased to 2.67 ± 0.09 mg/kg/min (DAPA) and 2.61 ± 0.08 mg/kg/min (DAPA/SAXA), despite reductions in fasting plasma glucose by 47 and 77 mg/dL, respectively, and no changes in PCB. Baseline plasma free fatty acids rose by 40 µmol/L with DAPA but declined by -110 with PCB and -90 µmol/L with DAPA/SAXA (P < 0.05, Pre-Tx vs. Post-Tx). In DAPA, carbohydrate oxidation rates decreased from 1.1 ± 0.1 to 0.7 ± 0.1 mg/kg/min, whereas lipid oxidation rates increased from 0.6 ± 0.1 to 0.8 ± 0.1 mg/kg/min (P < 0.01). In DAPA/SAXA, the shift in carbohydrate (1.1 ± 0.1 to 0.9 ± 0.1 mg/kg/min) and lipid (0.6 ± 0.1 to 0.7 ± 0.1 mg/kg/min) oxidation was attenuated (P < 0.05).

CONCLUSIONS

The addition of SAXA to DAPA resulted in superior glycemic control compared with DAPA monotherapy partly because of increased glucose utilization and oxidation. Although the decrease in insulin/glucagon ratio was prevented by SAXA, EGP paradoxical elevation persisted, indicating that other factors mediate EGP changes in response to SGLT2i-induced glucosuria.

The GLP1R Agonist Liraglutide Reduces Hyperglucagonemia Induced by the SGLT2 Inhibitor Dapagliflozin via Somatostatin Release

The newest classes of anti-diabetic agents include sodium-glucose cotransporter 2 (SGLT2) inhibitors and glucagon-like peptide 1 receptor (GLP1R) agonists. The SGLT2 inhibitor dapagliflozin reduces glucotoxicity by glycosuria but elevates glucagon secretion. The GLP1R agonist liraglutide inhibits glucagon; therefore, we hypothesize that the cotreatment of dapagliflozin with liraglutide could reduce hyperglucagonemia and hyperglycemia. Here we use five complementary models: human islet cultures, healthy mice, db/db mice, diet-induced obese (DIO) mice, and somatostatin receptor-2 (SSTR2) KO mice. A single administration of liraglutide and dapagliflozin in combination improves glycemia and reduces dapagliflozin-induced glucagon secretion in diabetic mice. Chronic treatment with liraglutide and dapagliflozin produces a sustainable reduction of glycemia compared with each drug alone. Moreover, liraglutide reduces dapagliflozin-induced glucagon secretion by enhancing somatostatin release, as demonstrated by SSTR2 inhibition in human islets and in mice. Collectively, these data provide mechanistic insights into how intra-islet GLP1R activation is critical for the regulation of glucose homeostasis.

Renal physiology of glucose handling and therapeutic implications

The rationale for using sodium-glucose cotransporter 2 (SGLT2) inhibitors in patients with type 2 diabetes (T2D) has evolved over the last decade. Due to the effects on glucosuria and body weight loss, SGLT2 inhibitors were originally approved for glycemic control in T2D. Since glucosuria is attenuated in chronic kidney disease (CKD) Stages 3–5, initial regulatory approval for SGLT2 inhibitor use was limited to patients with T2D and preserved estimated glomerular filtration rate. Over time, however, it has become increasingly apparent that these therapies have a variety of important pharmacodynamic and clinical effects beyond glycemic lowering, including antihypertensive and antialbuminuric properties, and the ability to reduce glomerular hypertension. Importantly, these sodium-related effects are preserved across CKD stages, despite attenuated glycemic effects, which are lost at CKD Stage 4. With the completion of cardiovascular (CV) outcome safety trials—EMPA-REG OUTCOME, CANVAS Program and DECLARE TIMI-58—in addition to reductions in CV events, SGLT2 inhibition consistently reduces hard renal endpoints. Importantly, these CV and renal effects are independent of glycemic control. Subsequent data from the recent CREDENCE trial—the first dedicated renal protection trial with SGLT-2 inhibition—demonstrated renal and CV benefits in albuminuric T2D patients, pivotal results that have expanded the clinical importance of these therapies. Ongoing trials will ultimately determine whether SGLT2 inhibition will have a role in renal protection in other clinical settings, including nondiabetic CKD and type 1 diabetes.

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.

Effect of Glucagon on Ischemic Heart Disease and Its Risk Factors: A Mendelian Randomization Study

CONTEXT

Glucagon acts reciprocally with insulin to regular blood glucose. However, the effect of glucagon on cardiovascular disease has not been widely studied. It has been suggested that insulin may increase the risk of ischemic heart disease.

OBJECTIVE

To investigate whether glucagon, the main counteracting hormone of insulin, plays a role in development of ischemic heart disease.

DESIGN, SETTING, AND PARTICIPANTS

In this 2-sample Mendelian randomization study, we estimated the causal effect of glucagon on ischemic heart disease and its risk factors using the inverse-variance weighted method with multiplicative random effects and multiple sensitivity analyses. Genetic associations with glucagon and ischemic heart disease and its risk factors, including type 2 diabetes and fasting insulin, were obtained from publicly available genome-wide association studies.

MAIN OUTCOME MEASURE

Odds ratio for ischemic heart disease and its risk factors per 1 standard deviation change in genetically predicted glucagon.

RESULTS

Twenty-four single-nucleotide polymorphisms strongly (P < 5 × 10-6) and independently (r2 < 0.05) predicting glucagon were obtained. Genetically predicted higher glucagon was associated with an increased risk of ischemic heart disease (inverse-variance weighted odds ratio, 1.03; 95% confidence interval, 1.0003-1.05) but not with type 2 diabetes (inverse-variance weighted odds ratio, 0.998, 95% confidence interval, 0.97-1.03), log-transformed fasting insulin (inverse-variance weighted beta, 0.002, 95% confidence interval, -0.01 to 0.01), other glycemic traits, blood pressure, reticulocyte, or lipids.

CONCLUSION

Glucagon might have an adverse impact on ischemic heart disease. Relevance of the underlying pathway to existing and potential interventions should be investigated.

Combination Therapy With Canagliflozin Plus Liraglutide Exerts Additive Effect on Weight Loss, but Not on HbA1c, in Patients With Type 2 Diabetes

OBJECTIVE

To examine the effect of combination therapy with canagliflozin plus liraglutide on HbA_1c, endogenous glucose production (EGP), and body weight versus each therapy alone.

RESEARCH DESIGN AND METHODS

Forty-five patients with poorly controlled (HbA_1c 7-11%) type 2 diabetes mellitus (T2DM) on metformin with or without sulfonylurea received a 9-h measurement of EGP with [3-³H]glucose infusion, after which they were randomized to receive 1) liraglutide 1.2 mg/day (LIRA), 2) canagliflozin 100 mg/day (CANA), or 3) liraglutide 1.2 mg plus canagliflozin 100 mg (CANA/LIRA) for 16 weeks. At 16 weeks, the EGP measurement was repeated.

RESULTS

The mean decrease from baseline to 16 weeks in HbA_1c was -1.67 ± 0.29% (P = 0.0001), -0.89 ± 0.24% (P = 0.002), and -1.44 ± 0.39% (P = 0.004) in patients receiving CANA/LIRA, CANA, and LIRA, respectively. The decrease in body weight was -6.0 ± 0.8 kg (P < 0.0001), -3.5 ± 0.5 kg (P < 0.0001), and -1.9 ± 0.8 kg (P = 0.03), respectively. CANA monotherapy caused a 9% increase in basal rate of EGP (P < 0.05), which was accompanied by a 50% increase (P < 0.05) in plasma glucagon-to-insulin ratio. LIRA monotherapy reduced plasma glucagon concentration and inhibited EGP. In CANA/LIRA-treated patients, EGP increased by 15% (P < 0.05), even though the plasma insulin response was maintained at baseline and the CANA-induced rise in plasma glucagon concentration was blocked.

CONCLUSIONS

These results demonstrate that liraglutide failed to block the increase in EGP caused by canagliflozin despite blocking the rise in plasma glucagon and preventing the decrease in plasma insulin concentration caused by canagliflozin. The failure of liraglutide to prevent the increase in EGP caused by canagliflozin explains the lack of additive effect of these two agents on HbA_1c.

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.

Combining Glucagon-Like Peptide 1 Receptor Agonists and Sodium-Glucose Cotransporter 2 Inhibitors to Target Multiple Organ Defects in Type 2 Diabetes

Long-term risks of macro- and microvascular complications may be reduced in people with type 2 diabetes who achieve early and sustained glycemic control. Delays in attaining A1C goals are associated with poor long-term cardiovascular (CV) outcomes. Glucagon-like peptide 1 (GLP-1) receptor agonists and sodium-glucose cotransporter 2 (SGLT2) inhibitors are glucose-lowering therapies that act through complementary mechanisms of action with regard to the pathophysiologic defects of type 2 diabetes. Trials of agents in both drug classes have demonstrated improvements in CV and renal outcomes. This review discusses the rationale for combination therapy with a GLP-1 receptor agonist and an SGLT2 inhibitor, including early initiation of this combination in newly diagnosed patients. This combination may lead to timely glycemic control and potentially additive CV and renal benefits. Clinical studies of the combination have shown partially additive effects on A1C reduction, additive effects on weight reduction, and potentially synergistic effects on blood pressure reduction. Long-term studies are needed to determine whether the combination provides an additional effect on CV and renal outcomes compared with agents from either drug class when used alone.

Evidence Against an Important Role of Plasma Insulin and Glucagon Concentrations in the Increase in EGP Caused by SGLT2 Inhibitors

Sodium-glucose cotransport 2 inhibitors (SGLT2i) lower plasma glucose but stimulate endogenous glucose production (EGP). The current study examined the effect of dapagliflozin on EGP while clamping plasma glucose, insulin, and glucagon concentrations at their fasting level. Thirty-eight patients with type 2 diabetes received an 8-h measurement of EGP ([3-³H]-glucose) on three occasions. After a 3-h tracer equilibration, subjects received 1) dapagliflozin 10 mg (n = 26) or placebo (n = 12); 2) repeat EGP measurement with the plasma glucose concentration clamped at the fasting level; and 3) repeat EGP measurement with inhibition of insulin and glucagon secretion with somatostatin infusion and replacement of basal plasma insulin and glucagon concentrations. In study 1, the change in EGP (baseline to last hour of EGP measurement) in subjects receiving dapagliflozin was 22% greater (+0.66 ± 0.11 mg/kg/min, P < 0.05) than in subjects receiving placebo, and it was associated with a significant increase in plasma glucagon and a decrease in the plasma insulin concentration compared with placebo. Under glucose clamp conditions (study 2), the change in plasma insulin and glucagon concentrations was comparable in subjects receiving dapagliflozin and placebo, yet the difference in EGP between dapagliflozin and placebo persisted (+0.71 ± 0.13 mg/kg/min, P < 0.01). Under pancreatic clamp conditions (study 3), dapagliflozin produced an initial large decrease in EGP (8% below placebo), followed by a progressive increase in EGP that was 10.6% greater than placebo during the last hour. Collectively, these results indicate that 1) the changes in plasma insulin and glucagon concentration after SGLT2i administration are secondary to the decrease in plasma glucose concentration, and 2) the dapagliflozin-induced increase in EGP cannot be explained by the increase in plasma glucagon or decrease in plasma insulin or glucose concentrations.

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.

Empagliflozin Effectively Lowers Liver Fat Content in Well-Controlled Type 2 Diabetes: A Randomized, Double-Blind, Phase 4, Placebo-Controlled Trial

OBJECTIVE

To evaluate whether the sodium-glucose cotransporter 2 inhibitor empagliflozin (EMPA) reduces liver fat content (LFC) in recent-onset and metabolically well-controlled type 2 diabetes (T2D).

RESEARCH DESIGN AND METHODS

Patients with T2D (n = 84) (HbA_1c 6.6 ± 0.5% [49 ± 10 mmol/mol], known disease duration 39 ± 27 months) were randomly assigned to 24 weeks of treatment with 25 mg daily EMPA or placebo. The primary end point was the difference of the change in LFC as measured with magnetic resonance methods from 0 (baseline) to 24 weeks between groups. Tissue-specific insulin sensitivity (secondary outcome) was assessed by two-step clamps using an isotope dilution technique. Exploratory analysis comprised circulating surrogate markers of insulin sensitivity and liver function. Statistical comparison was done by ANCOVA adjusted for respective baseline values, age, sex, and BMI.

RESULTS

EMPA treatment resulted in a placebo-corrected absolute change of -1.8% (95% CI -3.4, -0.2; P = 0.02) and relative change in LFC of -22% (-36, -7; P = 0.009) from baseline to end of treatment, corresponding to a 2.3-fold greater reduction. Weight loss occurred only with EMPA (placebo-corrected change -2.5 kg [-3.7, -1.4]; P < 0.001), while no placebo-corrected change in tissue-specific insulin sensitivity was observed. EMPA treatment also led to placebo-corrected changes in uric acid (-74 mol/L [-108, -42]; P < 0.001) and high-molecular-weight adiponectin (36% [16, 60]; P < 0.001) levels from 0 to 24 weeks.

CONCLUSIONS

EMPA effectively reduces hepatic fat in patients with T2D with excellent glycemic control and short known disease duration. Interestingly, EMPA also decreases circulating uric acid and raises adiponectin levels despite unchanged insulin sensitivity. EMPA could therefore contribute to the early treatment of nonalcoholic fatty liver disease in T2D.

Effect of Combination Therapy of Canagliflozin Added to Teneligliptin Monotherapy in Japanese Subjects with Type 2 Diabetes Mellitus: A Retrospective Study

Recently, dipeptidyl peptidase-4 (DPP-4) inhibitors and sodium-glucose cotransporter 2 (SGLT2) inhibitors have been very often used in subjects with type 2 diabetes mellitus (T2DM). In addition, combination drugs of both inhibitors have attracted much attention in aspects of its cost-effectiveness and improvement of patients' adherence. However, it is still poorly understood which factors are related to the efficacy of SGLT2 inhibitors as add-on therapy to DPP-4 inhibitors. Therefore, we aimed to elucidate in which type of individuals and/or under which conditions canagliflozin as add-on therapy to teneligliptin could exert more beneficial effects on glycemic control and/or renal protection. We retrospectively analyzed 56 Japanese subjects with T2DM in the real-world clinical practice. Three months after starting the combination therapy, the change of HbA1c (ΔHbA1c) was strongly related to HbA1c levels at baseline. As expected, serum glucagon level was increased after starting the combination therapy. Interestingly, however, the change of glucagon levels (Δglucagon) was not related to HbA1c levels at baseline, ΔHbA1c, and other parameters, which indicated that the increase of glucagon did not clinically affect the effectiveness of combination therapy. In addition, the change of urinary albumin excretion (ΔUAE) was negatively correlated with systolic blood pressure and HbA1c levels at baseline and positively correlated with the change of systolic blood pressure (ΔsBP) in univariate analysis. Furthermore, in multivariate analysis, only ΔsBP was the independent factor associated with ΔUAE. Taken together, canagliflozin as add-on therapy to teneligliptin improves glycemic control in a Δglucagon-independent manner and reduces UAE in a ΔsBP-dependent manner in Japanese subjects with T2DM.

Efficacy and safety of GLP-1 receptor agonists as add-on to SGLT2 inhibitors in type 2 diabetes mellitus: A meta-analysis

GLP-1 receptor agonists (GLP-1RA) and SGLT2 inhibitors (SGLT2i) have been associated with improved glycemic control, body weight loss and favorable changes in cardiovascular risk factors and outcomes. We conducted a systematic review and meta-analysis to evaluate the effects of the addition of GLP-1RA to SGLT2i in patients with type 2 diabetes mellitus and inadequate glycemic control. Six databases were searched until March 2019. Randomized controlled trials (RCT) with a follow-up of at least 24 weeks reporting on HbA1c, body weight, systolic blood pressure, lipids, achievement of HbA1c < 7%, requirement of rescue therapy due to hyperglycemia and hypoglycemic events were selected. Four RCTs were included. Compared to SGLT2i, the GLP-1RA/SGLT2i combination was associated with greater reduction in HbA1c (-0.74%), body weight (-1.61 kg), and systolic blood pressure (-3.32 mmHg). A higher number of patients achieved HbA1c < 7% (RR = 2.15), with a lower requirement of rescue therapy (RR = 0.37) and similar incidence of hypoglycemia. Reductions in total and LDL cholesterol were found. The present review supports treatment intensification with GLP-1RA in uncontrolled type 2 diabetes on SGLT2i. This drug regimen could provide improved HbA1c control, together with enhanced weight loss and blood pressure and lipids control.

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.

Concurrent Use of Teneligliptin and Canagliflozin Improves Glycemic Control with Beneficial Effects on Plasma Glucagon and Glucagon-Like Peptide-1: A Single-Arm Study

INTRODUCTION

We investigated the mechanisms of the glucose-lowering effects of teneligliptin and canagliflozin, a sodium-glucose cotransporter-2 (SGLT2) inhibitor, by monitoring several gastrointestinal peptides using the most appropriate measuring methods during multiple meal tolerance tests (MTTs) and flash glucose monitoring.

METHODS

Twelve Japanese patients with type 2 diabetes were enrolled in the 14-day study. Subjects were treated with teneligliptin 20 mg/day from day 4, followed by a combination tablet of teneligliptin 20 mg and canagliflozin 100 mg (T/C) per day from day 11. MTTs were conducted on days 3 (premedication; Pre), 10 (teneligliptin; T) and 13 (T/C) to evaluate plasma glucose, C-peptide, glucagon, active glucagon-like peptide-1 (GLP-1), active gastric inhibitory polypeptide (GIP), ghrelin and des-acyl ghrelin.

RESULTS

Plasma glucose was significantly decreased with the progress of treatment intervention, and C-peptide was significantly decreased in T/C compared to the others. Plasma postprandial glucagon was increased for 90 min from fasting in Pre, but only for 30 min in T and T/C. Plasma postprandial active GLP-1 was significantly increased in T compared to Pre, and that of T/C was significantly higher than T. Plasma postprandial active GIP was increased in T and T/C compared to Pre. Plasma ghrelin and des-acyl ghrelin levels did not change during the treatment.

CONCLUSION

Teneligliptin increased incretin hormones and suppressed postprandial glucagon secretion as expected. Concurrent use of canagliflozin and teneligliptin improved glycemic control without increasing postprandial glucagon secretion, and increased postprandial GLP-1 secretion and decreased the required amount of postprandial insulin secretion. The underlying mechanisms may involve canagliflozin's inhibitory activity against not only SGLT2 but also SGLT1.

TRIAL REGISTRATION

UMIN identifier, UMIN000030043.

FUNDING

Mitsubishi Tanabe Pharma Corporation and a Grant for Clinical Research from Miyazaki University Hospital.

No direct effect of SGLT2 activity on glucagon secretion

AIMS/HYPOTHESIS

Sodium-glucose cotransporter (SGLT) 2 inhibitors constitute a new class of glucose-lowering drugs, but they increase glucagon secretion, which may counteract their glucose-lowering effect. Previous studies using static incubation of isolated human islets or the glucagon-secreting cell line α-TC1 suggested that this results from direct inhibition of alpha cell SGLT1/2-activity. The aim of this study was to test whether the effects of SGLT2 on glucagon secretion demonstrated in vitro could be reproduced in a more physiological setting.

METHODS

We explored the effect of SGLT2 activity on glucagon secretion using isolated perfused rat pancreas, a physiological model for glucagon secretion. Furthermore, we investigated Slc5a2 (the gene encoding SGLT2) expression in rat islets as well as in mouse and human islets and in mouse and human alpha, beta and delta cells to test for potential inter-species variations. SGLT2 protein content was also investigated in mouse, rat and human islets.

RESULTS

Glucagon output decreased three- to fivefold within minutes of shifting from low (3.5 mmol/l) to high (10 mmol/l) glucose (4.0 ± 0.5 pmol/15 min vs 1.3 ± 0.3 pmol/15 min, p < 0.05). The output was unaffected by inhibition of SGLT1/2 with dapagliflozin or phloridzin or by addition of the SGLT1/2 substrate α-methylglucopyranoside, whether at low or high glucose concentrations (p = 0.29-0.99). Insulin and somatostatin secretion (potential paracrine regulators) was also unaffected. Slc5a2 expression and SGLT2 protein were marginal or below detection limit in rat, mouse and human islets and in mouse and human alpha, beta and delta cells.

CONCLUSIONS/INTERPRETATION

Our combined data show that increased plasma glucagon during SGLT2 inhibitor treatment is unlikely to result from direct inhibition of SGLT2 in alpha cells, but instead may occur downstream of their blood glucose-lowering effects.

Mechanistic insights from sequential combination therapy with a sodium glucose co-transporter-2 inhibitor and a dipeptidyl peptidase-4 inhibitor: Results from the CANARIS Trial using canagliflozin and teneligliptin

AIM

To elucidate the mechanisms involved in the sequential use of SGLT2 and DPP4 inhibitors (SGLT2i and DPP-4i).

METHODS

Twenty-six type-2 diabetes mellitus patients were recruited into a stepped regimen of 100 mg of canagliflozin daily from day 1, supplemented with 20 mg of teneligliptin daily from day 4. Glucose (Glu), insulin and glucagon were measured at fasting and after ingesting a mixed meal on days 1, 4 and 6.

RESULTS

Canagliflozin decreased fasting plasma glucose to an extent inversely proportional to the change in the glucagon-to-insulin (G/I) ratio. This correlation at fasting was maintained when adding teneligliptin, while the change in the area under the curve of Glu (GluAUC) correlated closely with that in the G/I ratio at fasting and 60 min with canagliflozin. Moreover, these correlations persisted at 60 and 120 min postprandially, but not at fasting on day 6 when teneligliptin was added.

CONCLUSION

The result suggested that the dominant mechanism responsible for the glucose metabolism reflected in the G/I ratio was attributable to SGLT2i and that its active mechanism persisted, despite adding a DPP-4i.

Glucagon Levels During Short-Term SGLT2 Inhibition Are Largely Regulated by Glucose Changes in Patients With Type 2 Diabetes

CONTEXT

The mechanism mediating sodium glucose cotransporter-2 (SGLT2) inhibitor-associated increase in glucagon levels is unknown.

OBJECTIVE

To assess short-term effects on glucagon, other hormones, and energy substrates after SGLT2 inhibition and whether such effects are secondary to glucose lowering. The impact of adding a dipeptidyl peptidase-4 inhibitor was addressed.

DESIGN, SETTING, AND PATIENTS

A phase 4, single-center, randomized, three-treatment crossover, open-label study including 15 patients with type 2 diabetes treated with metformin.

INTERVENTIONS

Patients received a single-dose of dapagliflozin 10 mg accompanied by the following in randomized order: isoglycemic clamp (experiment DG); saline infusion (experiment D); or saxagliptin 5 mg plus saline infusion (experiment DS). Directly after 5-hour infusions, a 2-hour oral glucose tolerance test (OGTT) was performed.

RESULTS

Glucose and insulin levels were stable in experiment DG and decreased in experiment D [P for difference (Pdiff) < 0.001]. Glucagon-to-insulin ratio (Pdiff < 0.001), and levels of glucagon (Pdiff < 0.01), nonesterified fatty acids (Pdiff < 0.01), glycerol (Pdiff < 0.01), and β-OH-butyrate (Pdiff < 0.05) were lower in DG vs D. In multivariate analysis, change in glucose level was the main predictor of change in glucagon level. In DS, glucagon and active GLP-1 levels were higher than in D, but glucose and insulin levels did not differ. During OGTT, glucose levels rose less and glucagon levels fell more in DS vs D.

CONCLUSION

The degree of glucose lowering markedly contributed to regulation of glucagon and insulin secretion and to lipid mobilization during short-term SGLT2 inhibition.

The role of glucagon in the possible mechanism of cardiovascular mortality reduction in type 2 diabetes patients

AIM

Type 2 diabetes (T2D) is one of the major public health issues worldwide. The main cause of mortality and morbidity among T2D patients are cardiovascular (CV) causes. Various antidiabetics are used in T2D treatment, but until recently they lacked clear evidence of the reduction in CV mortality and all-cause mortality as independent study end-points. The aim of this article was to present and critically evaluate potential mechanisms behind the remarkable results documented in trials with new antidiabetics for the treatment of T2D.

METHODS

Relevant data were collected using the MEDLINE, PubMed, EMBASE, Web of Science, Science Direct, and Scopus databases with the key words: "type 2 diabetes," "mortality," "glucagon," "empagliflozin," "liraglutide," "insulin" and "QTc." Searches were not limited to specific publication types or study designs.

RESULTS

The EMPA-REG OUTCOME trial with empagliflozin and LEADER trial with liraglutide presented remarkable results regarding the reduction in mortality in T2D treatment. However, the potential mechanism for those beneficial effects is difficult to determine. It is not likely that improvements in classic CV risk factors are responsible for the observed effect. A potential mechanism may be caused by the elevation of postprandial (PP) glucagon concentrations that can be seen with an empagliflozin and liraglutide therapy, which could have beneficial effects considering the myocardial electrical stability in T2D patients.

CONCLUSION

This hypothesis throws new light upon possible mechanisms of reduction in mortality in T2D patients.

Hepatic ketogenic insufficiency reprograms hepatic glycogen metabolism and the lipidome

While several molecular targets are under consideration, mechanistic underpinnings of the transition from uncomplicated nonalcoholic fatty liver disease (NAFLD) to nonalcoholic steatohepatitis (NASH) remain unresolved. Here we apply multiscale chemical profiling technologies to mouse models of deranged hepatic ketogenesis to uncover potential NAFLD driver signatures. Use of stable-isotope tracers, quantitatively tracked by nuclear magnetic resonance (NMR) spectroscopy, supported previous observations that livers of wild-type mice maintained long term on a high-fat diet (HFD) exhibit a marked increase in hepatic energy charge. Fed-state ketogenesis rates increased nearly 3-fold in livers of HFD-fed mice, a greater proportionate increase than that observed for tricarboxylic acid (TCA) cycle flux, but both of these contributors to overall hepatic energy homeostasis fueled markedly increased hepatic glucose production (HGP). Thus, to selectively determine the role of the ketogenic conduit on HGP and oxidative hepatic fluxes, we studied a ketogenesis-insufficient mouse model generated by knockdown of the mitochondrial isoform of 3-hydroxymethylglutaryl-CoA synthase (HMGCS2). In response to ketogenic insufficiency, TCA cycle flux in the fed state doubled and HGP increased more than 60%, sourced by a 3-fold increase in glycogenolysis. Finally, high-resolution untargeted metabolomics and shotgun lipidomics performed using ketogenesis-insufficient livers in the fed state revealed accumulation of bis(monoacylglycero)phosphates, which also accumulated in livers of other models commonly used to study NAFLD. In summary, natural and interventional variations in ketogenesis in the fed state strongly influence hepatic energy homeostasis, glucose metabolism, and the lipidome. Importantly, HGP remains tightly linked to overall hepatic energy charge, which includes both terminal fat oxidation through the TCA cycle and partial oxidation via ketogenesis.