The Effects of Exenatide and Metformin on Endothelial Function in Newly Diagnosed Type 2 Diabetes Mellitus Patients: A Case-Control Study

Zein-Based Triple-Drug Nanoparticles to Promote Anti-Inflammatory Responses for Nerve Regeneration after Spinal Cord Injury

Defects in autophagy contribute to neurological deficits and motor dysfunction after spinal cord injury. Here a nanosystem is developed to deliver autophagy-promoting, anti-inflammatory drugs to nerve cells in the injured spinal cord. Celastrol, metformin, and everolimus as the mTOR inhibitor are combined into the zein-based nanoparticles, aiming to solubilize the drugs and prolong their circulation. The nanoparticles are internalized by BV2 microglia and SH-SY5Y neuron-like cells in culture; they inhibit the secretion of inflammatory factors by BV2 cells after insult with lipopolysaccharide, and they protect SH-SY5Y cells from the toxicity of H2O2. In a rat model of spinal cord injury, the nanoparticles mitigate inflammation and promote spinal cord repair. In the in vitro and in vivo experiments, the complete nanoparticles function better than the free drugs or nanoparticles containing only one or two drugs. These results suggest that the triple-drug nanoparticles show promise for treating spinal cord injury.

Narrative review of data supporting alternate first-line therapies over metformin in type 2 diabetes

Purpose

Metformin has been the first-line treatment for type 2 diabetes mellitus as monotherapy or concomitantly with other glucose-lowering therapies due to its efficacy, safety, and affordability. Recent studies on the cardioprotective and renoprotective benefits of glucagon-like peptide-1 receptor agonists (GLP-1 RA) and sodium-glucose cotransporter-2 inhibitors (SGLT-2i) have influenced guidelines on diabetes management to consider these newer agents as alternative first-line therapies. This paper explores the literature supporting the use of these newer medications alone as a first-line agent in place of metformin.

Methods

A review of citations from the most recent guidelines along with a literature search via PubMed was completed to review (1) what, historically, made metformin first-line (2) if newer agents' benefits remain when used without metformin (3) how newer agents compare against metformin when used without it.

Results

Evaluation of the historical literature was completed to summarize the key findings that support metformin as a first-line therapy agent. Additionally, an assessment of the literature reveals that the benefits of these two newer classes are independent of concomitant metformin therapy. Finally, studies have demonstrated that these newer agents can be either non-inferior or sometimes superior to metformin when used as monotherapy.

Conclusion

GLP-1 RA and SGLT-2i can be considered as first line monotherapies for select patients with high cardiovascular risks, renal disease, or weight loss requirements. However, pharmacoeconomic considerations along with lesser long-term safety outcomes should limit these agents' use in certain patients as the management of diabetes continues to transition towards shared-decision making.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-024-01406-6.

The association between multiple trajectories of macronutrient intake and the risk of new-onset diabetes in Chinese adults

BACKGROUND

The association between macronutrient intake and diabetes is unclear. We used data from the China Health and Nutrition Survey to explore the association between macronutrient intake trajectories and diabetes risk in this study.

METHODS

We included 6755 participants who did not have diabetes at baseline and participated in at least three surveys. The energy supply ratio of carbohydrate, protein, and fat was further calculated from dietary data; different macronutrient trajectories were determined using multitrajectory models; and multiple Cox regression models were used to evaluate the association between these trajectories and diabetes.

RESULTS

We found three multitrajectories: decreased low carbohydrate-increased moderate protein-increased high fat (DLC-IMP-IHF), decreased high carbohydrate-moderate protein-increased low fat (DHC-MP-ILF), and balanced-macronutrients (BM). Compared to the BM trajectory, DHC-MP-ILF trajectories were significantly associated with increased risk of diabetes (hazard ratio [HR]: 3.228, 95% confidence interval [CI]: 1.571-6.632), whereas no association between DLC-IMP-IHF trajectories and diabetes was found in our study (HR: 0.699, 95% CI: 0.351-1.392).

CONCLUSIONS

The downward trend of high carbohydrate and the increasing trend of low fat increased the risk of diabetes in Chinese adults.

Metformin Impedes Oxidation of LDL In Vitro

Metformin is the most commonly prescribed glucose-lowering drug for the treatment of type 2 diabetes. The aim of this study was to investigate whether metformin is capable of impeding the oxidation of LDL, a crucial step in the development of endothelial dysfunction and atherosclerosis. LDL was oxidized by addition of CuCl2 in the presence of increasing concentrations of metformin. The extent of LDL oxidation was assessed by measuring lipid hydroperoxide and malondialdehyde concentrations, relative electrophoretic mobilities, and oxidation-specific immune epitopes. Cytotoxicity of oxLDL in the vascular endothelial cell line EA.hy926 was assessed using the alamarBlue viability test. Quantum chemical calculations were performed to determine free energies of reactions between metformin and radicals typical for lipid oxidation. Metformin concentration-dependently impeded the formation of lipid hydroperoxides, malondialdehyde, and oxidation-specific immune epitopes when oxidation of LDL was initiated by addition of Cu2+. The cytotoxicity of oxLDL was reduced when it was obtained under increasing concentrations of metformin. The quantum chemical calculations revealed that only the reaction of metformin with hydroxyl radicals is exergonic, whereas the reactions with hydroperoxyl radicals or superoxide radical anions are endergonic. Metformin, beside its glucose-lowering effect, might be a suitable agent to impede the development of atherosclerosis and associated CVD. This is due to its capability to impede LDL oxidation, most likely by scavenging hydroxyl radicals.

Implantable device actuated by manual button clicks for noninvasive self-drug administration

Self-injectable therapy has several advantages in the treatment of metabolic disorders. However, frequent injections with needles impair patient compliance and medication adherence. Therefore, we develop a fully implantable device capable of on-demand administration of self-injection drugs via noninvasive manual button clicks on the outer skin. The device is designed to infuse the drug only at the moment of click actuation, which allows for an accurate and reproducible drug infusion, and also prevents unwanted drug leakage. Using a mechanical means of drug infusion, this implantable device does not contain any electronic compartments or batteries, making it compact, and semi-permanent. When tested in animals, the device can achieve subcutaneous injection-like pharmacokinetic and pharmacodynamic effects for self-injection drugs such as exenatide, insulin, and glucagon.

Metformin exerts synergistic anti-proliferative effects with liraglutide in human umbilical vein endothelial cells (HUVECs)

Objectives

Metformin (Met) and liraglutide (Lira) have been approved to treat type 2 diabetes mellitus and have cardioprotective effects.

Materials and Methods

Human umbilical vein endothelial cells (HUVECs) were incubated with Met, Lira, or their combination in this study.

Results

Results showed that the synergistic inhibitory effect of the two drugs on HUVECs proliferation was significant (75%) after 48 hr drug exposure. In addition, either Lira or Met alone had a marked tendency to inhibit the migration of HUVECs (42% and 39%). Almost a complete inhibition (97%) was demonstrated in combinational use after 48 hr treatment. After combining these two drugs, the apoptosis rate raised to 68%, which was a significant approval of synergistic apoptosis induction of Met and Lira. The combinational group indicated a substantial increase in VEGF, PDGF, and MMP-9 at 24 hr compared with the control.

Conclusion

This study showed that combination therapy with Lira and Met could effectively reduce cell proliferation, induce apoptosis, and inhibit cell migration in the HUVECs. This study provides evidence to support using Met in combination with Lira as a treatment option for patients with type-2 diabetes and cancer.

Effect of metformin as an add-on therapy on neuregulin-4 levels and vascular-related complications in adolescents with type 1 diabetes: A randomized controlled trial

BACKGROUND

Inflammation is closely associated with atherosclerosis and plays a crucial role in the development of cardiovascular disease. Metformin sensitizes body cells to insulin, which may cause a reduction of atherogenic lipid fractions. Low neuregulin-4 (Nrg-4) levels, an adipokine, are linked to obesity, insulin resistance, impaired glucose tolerance and type 2 diabetes.

OBJECTIVES

We assessed the effect of oral supplementation with metformin on glycemic control, neuregulin-4 levels and carotid intima media thickness (CIMT) as a marker for subclinical atherosclerosis in adolescents with type 1 diabetes mellitus (T1DM) and microvascular complications.

METHODS

This randomized placebo-controlled trial included 80 type 1 diabetic patients with microvascular complications who were randomly divided to receive either 24 weeks of metformin 500 mg/day or matching placebo. Fasting blood glucose (FBG), HbA1c, C-reactive protein (CRP), urinary albumin creatinine ratio (UACR), lipid profile, Nrg-4 and CIMT were assessed at baseline and study end.

RESULTS

Both groups were well-matched as regards baseline clinical and laboratory data (p greater than 0.05). After 24-weeks, metformin therapy for the intervention group resulted in a significant decrease of HbA1c, CRP, UACR, total cholesterol and CIMT while Nrg-4 levels were increased compared with baseline levels (p < 0.001) and with placebo group(p < 0.001). Baseline Nrg-4 levels were negatively correlated to FBG, HbA1c, total cholesterol, CRP and CIMT. Metformin was well-tolerated.

CONCLUSIONS

Oral metformin supplementation once daily for 24 weeks as an adjuvant therapy to intensive insulin in pediatric T1DM was safe and effective in improving glycemic control, dyslipidemia and Nrg-4 levels; hence, it decreased inflammation, microvascular complications and subclinical atherosclerosis.

Glycaemia dynamics in gestational diabetes mellitus

Pregnant women may develop gestational diabetes mellitus (GDM), a disease of pregnancy characterised by maternal and fetal hyperglycaemia with hazardous consequences to the mother, the fetus, and the newborn. Maternal hyperglycaemia in GDM results in fetoplacental endothelial dysfunction. GDM-harmful effects result from chronic and short periods of hyperglycaemia. Thus, it is determinant to keep glycaemia within physiological ranges avoiding short but repetitive periods of hyper or hypoglycaemia. The variation of glycaemia over time is defined as 'glycaemia dynamics'. The latter concept regards with a variety of mechanisms and environmental conditions leading to blood glucose handling. In this review we summarized the different metrics for glycaemia dynamics derived from quantitative, plane distribution, amplitude, score values, variability estimation, and time series analysis. The potential application of the derived metrics from self-monitoring of blood glucose (SMBG) and continuous glucose monitoring (CGM) in the potential alterations of pregnancy outcome in GDM are discussed.

When Good Guys Turn Bad: Bone Marrow's and Hematopoietic Stem Cells' Role in the Pathobiology of Diabetic Complications

Diabetes strongly contributes to the development of cardiovascular disease, the leading cause of mortality and morbidity in these patients. It is widely accepted that hyperglycemia impairs hematopoietic stem/progenitor cell (HSPC) mobilization from the bone marrow (BM) by inducing stem cell niche dysfunction. Moreover, a recent study demonstrated that type 2 diabetic patients are characterized by significant depletion of circulating provascular progenitor cells and increased frequency of inflammatory cells. This unbalance, potentially responsible for the reduction of intrinsic vascular homeostatic capacity and for the establishment of a low-grade inflammatory status, suggests that bone BM-derived HSPCs are not only victims but also active perpetrators in diabetic complications. In this review, we will discuss the most recent literature on the molecular mechanisms underpinning hyperglycemia-mediated BM dysfunction and differentiation abnormality of HSPCs. Moreover, a section will be dedicated to the new glucose-lowering therapies that by specifically targeting the culprits may prevent or treat diabetic complications.

Endothelium as a Therapeutic Target in Diabetes Mellitus: From Basic Mechanisms to Clinical Practice

Endothelium plays an essential role in human homeostasis by regulating arterial blood pressure, distributing nutrients and hormones as well as providing a smooth surface that modulates coagulation, fibrinolysis and inflammation. Endothelial dysfunction is present in Diabetes Mellitus (DM) and contributes to the development and progression of macrovascular disease, while it is also associated with most of the microvascular complications such as diabetic retinopathy, nephropathy and neuropathy. Hyperglycemia, insulin resistance, hyperinsulinemia and dyslipidemia are the main factors involved in the pathogenesis of endothelial dysfunction. Regarding antidiabetic medication, metformin, gliclazide, pioglitazone, exenatide and dapagliflozin exert a beneficial effect on Endothelial Function (EF); glimepiride and glibenclamide, dipeptidyl peptidase-4 inhibitors and liraglutide have a neutral effect, while studies examining the effect of insulin analogues, empagliflozin and canagliflozin on EF are limited. In terms of lipid-lowering medication, statins improve EF in subjects with DM, while data from short-term trials suggest that fenofibrate improves EF; ezetimibe also improves EF but further studies are required in people with DM. The effect of acetylsalicylic acid on EF is dose-dependent and lower doses improve EF while higher ones do not. Clopidogrel improves EF, but more studies in subjects with DM are required. Furthermore, angiotensin- converting-enzyme inhibitors /angiotensin II receptor blockers improve EF. Phosphodiesterase type 5 inhibitors improve EF locally in the corpus cavernosum. Finally, cilostazol exerts favorable effect on EF, nevertheless, more data in people with DM are required.

Minimizing Hyperglycemia-Induced Vascular Endothelial Dysfunction by Inhibiting Endothelial Sodium-Glucose Cotransporter 2 and Attenuating Oxidative Stress: Implications for Treating Individuals With Type 2 Diabetes

This overview deals with mechanisms whereby hyperglycemia-induced oxidative stress compromises vascular endothelial function and provides a background for a recently published study illustrating the beneficial impact of endothelial sodium-glucose cotransporter 2 (SGLT2) inhibitors in attenuating hyperglycemia-induced vascular dysfunction in vitro. The data provide new insight that can possibly lead to improved drug therapy for people with type 2 diabetes. The working hypotheses that underpinned the experiments performed are provided, along with the findings of the study. For the causes of hyperglycemia-induced vascular endothelial dysfunction, the findings point to the key roles of: 1) functional endothelial SGLT2; 2) oxidative stress-induced signalling pathways including mammalian sarcoma virus kinase, the EGF receptor-kinase and protein kinase C; and 3) mitochondrial dysfunction triggered by hyperglycemia was mitigated by an SGLT2 inhibitor in the hyperglycemic mouse aorta vascular organ cultures. The overview sums up the approaches implicated by the study that can potentially counteract the detrimental impact of hyperglycemia on vascular function in people with diabetes, including the clinical use of SGLT2 inhibitors for those with type 2 diabetes already being treated, for example, with metformin, along with dietary supplementation with broccoli-derived sulforaphane and tetrahydrobiopterin. The caveats associated with the study for extending the findings from mice to humans are summarized, pointing to the need to validate the work using vascular tissues from humans. Suggestions for future clinical studies are made, including the assessment of the impact of the therapeutic strategies proposed on measurements of blood flow in subjects with diabetes.

The GLP-1 receptor agonist liraglutide protects against oxidized LDL-induced endothelial inflammation and dysfunction via KLF2

Cardiovascular complications are the major causes of the mortality and morbidities in diabetic patients. The diabetic patients have an increased risk of developing atherosclerosis, which could lead to heart attack and stroke. Glucagon-like peptide 1 (GLP-1) receptor agonists are a class of potent anti-glycemic agents to treat diabetes. Recently, several GLP-1 receptor agonists have been found to have cardiovascular benefit independent of their glucose lowing ability. Liraglutide is one of clinically approved effective GLP-1 receptor agonists. In this study, we explored the molecular mechanism of Liraglutide against oxidized low-density lipoprotein (ox-LDL) in cultured endothelial cells. Our data show that Liraglutide treatment ameliorates ox-LDL caused reduction of the transcriptional factor KLF2. In the same experiment, Liraglutide also rescues ox-LDL induced reduction of mitogen-activated protein kinase (MAPK) kinase extracellular signal regulated kinase 5 (ERK5) phosphorylation, and blockage of ERK5 activity by its inhibitor XMD8-92 abolishes the protection of Liraglutide on KLF2 expression. These facts suggest that the action of Liraglutide on endothelial KLF2 is dependent on ERK5. Liraglutide also recovers ox-LDL caused reduction of endothelial tight junctions protein Occludin and ameliorates ox-LDL induced endothelial monolayer permeability increase. On the other hand, Liraglutide inhibits ox-LDL induced expression of vascular adhesion molecules (E-selectin and vascular cell adhesion molecule 1), and prevents ox-LDL induced attachment of monocytes adhesion to endothelial cells. Moreover, Liraglutide mitigates ox-LDL triggered reduction of endothelial nitric oxide synthase (eNOS) expression and NO release. Collectively, our study provides multiple facets of the mechanisms that Liraglutide is a protective agent in endothelial cells and has the potential implication in therapeutic usage of vascular complication in diabetes patients. © 2019 IUBMB Life, 71(9):1347-1354, 2019.

Empagliflozin on top of metformin treatment improves arterial function in patients with type 1 diabetes mellitus

Background

Deteriorated arterial function and high incidence of cardiovascular events characterise diabetes mellitus. Metformin and recent antidiabetic drugs, SGLT2 inhibitors, reduce cardiovascular events. We explored the possible effects of empagliflozin’s effect on top of metformin treatment on endothelial function and arterial stiffness parameters in type 1 diabetes mellitus (T1DM) patients.

Methods

Forty T1DM patients were randomised into three treatment groups: (1) empagliflozin (25 mg daily), (2) metformin (2000 mg daily) and (3) empagliflozin/metformin (25 mg daily and 2000 mg daily, respectively). The fourth group received placebo. Arterial function was assessed at inclusion and after 12 weeks treatment by: endothelial function [brachial artery flow-mediated dilation (FMD), reactive hyperaemia index (RHI)], arterial stiffness [pulse wave velocity (PWV) and common carotid artery stiffness (β-stiffness)]. For statistical analysis one-way analysis of variance with Bonferroni post-test was used.

Results

Empagliflozin on top of metformin treatment significantly improved endothelial function as did metformin after 12 weeks of treatment: FMD [2.6-fold (P < 0.001) vs. 1.8-fold (P < 0.05)] and RHI [1.4-fold (P < 0.01) vs. 1.3-fold (P < 0.05)]. Empagliflozin on top of metformin treatment was superior to metformin in improving arterial stiffness parameters; it significantly improved PWV and β-stiffness compared to metformin [by 15.8% (P < 0.01) and by 36.6% (P < 0.05), respectively]. Metformin alone did not influence arterial stiffness.

Conclusion

Empagliflozin on top of metformin treatment significantly improved arterial stiffness compared to metformin in T1DM patients. Endothelial function was similarly improved in all treatment groups. Empagliflozin seems to possess a specific capacity to decrease arterial stiffness, which could support its cardioprotective effects observed in large clinical studies.

Trial registration Clinical trial registration: NCT03639545

Metformin: An Old Drug with New Applications

Metformin is a biguanide drug that has been used to treat type 2 diabetes mellitus for more than 60 years. The United Kingdom Prospective Diabetic Study (UKPDS) has shown metformin to improve mortality rates in diabetes patients, and recent studies suggest metformin has additional effects in treating cancer, obesity, nonalcoholic fatty liver disease (NAFLD), polycystic ovary syndrome (PCOS), and metabolic syndrome. Metformin has also been shown to alleviate weight gain associated with antipsychotic medication. Metformin has recently been extensively studied and emerging evidence suggests metformin decreases hepatocyte triglyceride accumulation in NAFLD and prevents liver tumorigenesis. Interestingly, studies have also shown metformin reduces visceral fat, suppresses white-adipose-tissue (WAT) extracellular matrix remodeling, and inhibits obesity-induced inflammation. However, clinical evidence for using metformin to treat NAFLD, cancer, metabolic syndrome, or to prevent hepatocellular carcinoma in NAFLD patients is lacking. This review therefore addresses the potential beneficial effects of metformin on NAFLD, its role in protecting against cardiac ischemia–reperfusion (I/R) injury, atherosclerosis, glucotoxicity, and lipotoxicity induced oxidative and ER stress in pancreatic β-cell dysfunction, as well as its underlying molecular mechanisms of action.

Microvascular Density and Circulating Endothelial Progenitor Cells Before and After Treatment with Incretin Mimetics in Diabetic Patients

INTRODUCTION

Glucagon-like peptide 1-receptor agonists (incretin mimetics) and dipeptidyl peptidase-4 inhibitors (incretin enhancers) have been recently introduced in the treatment of diabetes mellitus. In particular, incretin mimetics seems to have ancillary antioxidant/antinflammatory properties that might be involved in endothelial protection.

AIM

To investigate the effect of incretin mimetic therapy (liraglutide, exenatide) given to 11 patients with type 2 diabetes mellitus, on circulating endothelial progenitor cells (EPCs) (bone marrow-derived cells possibly participating in neovascularization and endothelial protection and repair) and capillary density.

METHODS

Four diabetic patients were treated with exenatide (5 μg twice daily for 4 weeks and then 10 μg twice daily for 3 weeks) and 7 with liraglutide (0.6 mg per day for 1 week and then 1.2 mg per day for 3 weeks). Peripheral venous blood samples were obtained before treatment (basal) and after 4 week in patients treated with liraglutide, and after 4 and 7 weeks in patients treated with exenatide, since drug titration is usually longer. EPCs were evaluated by flow cytometry as CD34⁺/KDR⁺ cells. Capillary density was evaluated by videomicroscopy, before and after venous congestion, in the dorsum of the 4th finger.

RESULTS

Patients treated with liraglutide (6 males 1 female, age 54 ± 12 years) showed a decrease in body mass index and blood pressure during treatment, while patients treated with exenatide (3 males 1 female, age 57 ± 6 years) did not show any relevant change. EPCs were significantly increased after treatment with exenatide, but not after treatment with liraglutide. Capillary density was slightly increased only after 4 weeks of treatment with exenatide, however the increase was no longer present at the final evaluation.

CONCLUSIONS

Treatment with exenatide, but not with liraglutide, was able to increase the number of circulating EPCs, possibly through an antioxidative/antiinflammatory effect.