Hormonal, Metabolic and Hemodynamic Adaptations to Glycosuria in Type 2 Diabetes Patients Treated with Sodium-Glucose Co-Transporter Inhibitors

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.

Sodium Glucose Co-Transporter 2 Inhibitors and the Cardiovascular System: Current Knowledge and Future Expectations

Diabetic cardiomyopathy is a well-recognized clinical entity and reflects a complex relationship between metabolic substrates and myocardial function. Sodium glucose co-transporter 2 (SGLT2) inhibitors are antidiabetic agents that are found to exert multiple cardioprotective effects. Large clinical trials showed their beneficial effects on patients with heart failure, reducing the rates of rehospitalizations and improving kidney function. The aim of this review is to summarize the latest evidence in the literature regarding the multiple effects of SGLT2 inhibitors on patients across the spectrum of cardiovascular diseases.

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.

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.

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.

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

OBJECTIVE

Sodium-glucose cotransporter 2 (SGLT2) inhibition causes an increase in endogenous glucose production (EGP). However, the mechanisms are unclear. We studied the effect of SGLT2 inhibitors on EGP in subjects with type 2 diabetes (T2D) and without diabetes (non-DM) in kidney transplant recipients with renal denervation.

RESEARCH DESIGN AND METHODS

Fourteen subjects who received a renal transplant (six with T2D [A1C 7.2 ± 0.1%] and eight non-DM [A1C 5.6 ± 0.1%) underwent measurement of EGP with [3-³H]glucose infusion following dapagliflozin (DAPA) 10 mg or placebo. Plasma glucose, insulin, C-peptide, glucagon, and titrated glucose-specific activity were measured.

RESULTS

Following placebo in T2D, fasting plasma glucose (FPG) (143 ± 14 to 124 ± 10 mg/dL; P = 0.02) and fasting plasma insulin (12 ± 2 to 10 ± 1.1 μU/mL; P < 0.05) decreased; plasma glucagon was unchanged, and EGP declined. After DAPA in T2D, FPG (143 ± 15 to 112 ± 9 mg/dL; P = 0.01) and fasting plasma insulin (14 ± 3 to 11 ± 2 μU/mL; P = 0.02) decreased, and plasma glucagon increased (all P < 0.05 vs. placebo). EGP was unchanged from baseline (2.21 ± 0.19 vs. 1.96 ± 0.14 mg/kg/min) in T2D (P < 0.001 vs. placebo). In non-DM following DAPA, FPG and fasting plasma insulin decreased, and plasma glucagon was unchanged. EGP was unchanged from baseline (1.85 ± 0.10 to 1.78 ± 0.10 mg/kg/min) after DAPA, whereas EGP declined significantly with placebo. When the increase in EGP production following DAPA versus placebo was plotted against the difference in urinary glucose excretion (UGE) for all patients, a strong correlation (r = 0.824; P < 0.001) was observed.

CONCLUSIONS

Renal denervation in patients who received a kidney transplant failed to block the DAPA-mediated stimulation of EGP in both individuals with T2D and non-DM subjects. The DAPA-stimulated rise in EGP is strongly related to the increase in UGE, blunting the decline in FPG.

[Reactive hypoglycemia - an interdisciplinary approach of the disease of XXI Century]

Reactive hypoglycemia is characterized by low blood glucose level in non-diabetic patients. It manifests as a syndrome of adrenergic and neuroglycopenic symptoms in the postprandial period, and their resolution occurs after consuming carbohydrates. The etiology of reactive hypoglycemia is not fully understood. It may occur in patients after gastrointestinal surgery due to too fast gastric emptying. Decreases in postprandial glucose are also observed in people with a pre-diabetes condition in which insulin secretion is disturbed. Hypoglycaemia can also be seen in patients with insulin resistance and hyperinsulinism. The aim of this study was to summarize existing knowledge about reactive hypoglycemia - etiology, diagnostic model and treatment.