Glucose Variability and β- Cell Response by GLP-1 Analogue added-on CSII for Patients with Poorly Controlled Type 2 Diabetes

Liraglutide Protects Against Brain Amyloid-β1-42 Accumulation in Female Mice with Early Alzheimer's Disease-Like Pathology by Partially Rescuing Oxidative/Nitrosative Stress and Inflammation

Alzheimer’s disease (AD) is the most common form of dementia worldwide, being characterized by the deposition of senile plaques, neurofibrillary tangles (enriched in the amyloid beta (Aβ) peptide and hyperphosphorylated tau (p-tau), respectively) and memory loss. Aging, type 2 diabetes (T2D) and female sex (especially after menopause) are risk factors for AD, but their crosslinking mechanisms remain unclear. Most clinical trials targeting AD neuropathology failed and it remains incurable. However, evidence suggests that effective anti-T2D drugs, such as the GLP-1 mimetic and neuroprotector liraglutide, can be also efficient against AD. Thus, we aimed to study the benefits of a peripheral liraglutide treatment in AD female mice. We used blood and brain cortical lysates from 10-month-old 3xTg-AD female mice, treated for 28 days with liraglutide (0.2 mg/kg, once/day) to evaluate parameters affected in AD (e.g., Aβ and p-tau, motor and cognitive function, glucose metabolism, inflammation and oxidative/nitrosative stress). Despite the limited signs of cognitive changes in mature female mice, liraglutide only reduced their cortical Aβ_1–42 levels. Liraglutide partially attenuated brain estradiol and GLP-1 and activated PKA levels, oxidative/nitrosative stress and inflammation in these AD female mice. Our results support the earlier use of liraglutide as a potential preventive/therapeutic agent against the accumulation of the first neuropathological features of AD in females.

Continuous subcutaneous insulin infusion combined with liraglutide reduced glycemic variability and oxidative stress in type 2 diabetes mellitus: a study based on the flash glucose monitoring system

We aimed to explore the use of the flash glucose monitoring (FGM) system in hospitalized newly diagnosed type 2 diabetes mellitus (T2DM) patients and to evaluate a new combination therapy of continuous subcutaneous insulin infusion (CSII) with or without liraglutide. This was an open-label, randomized study that was conducted in 60 newly diagnosed T2DM patients. The patients were randomized to receive either CSII (n = 30) or CSII + liraglutide (n = 30). The FGM system was used to assess the glycemic control and glycemic variability (GV) indices for 2 weeks. Mean blood glucose concentration (MBG), estimated hemoglobin A1c (HbA1c), and measures of GV, including the standard deviation of the mean glucose (SD), coefficient of variation (CV), interquartile range (IQR), mean amplitude of glycemic excursions (MAGE), largest amplitude of glycemic excursions (LAGE), and mean of daily difference (MODD) were compared between the two groups. Two oxidative stress biomarkers, 4-hydroxynonenal (4-HNE) and 8-hydroxydeoxyguanosine (8-OHdG), were measured before and after treatment. The estimated HbA1c and MBG decreased in both groups, especially the CSII + liraglutide group. SD, IQR, LAGE, and MODD were significantly lower in the CSII + liraglutide group than in the CSII group (all p < 0.05); there was no difference in CV or MAGE (p > 0.05). Similarly, the 4-HNE and 8-OHdG levels were significantly lower in the CSII + liraglutide group (p < 0.05). Our findings suggest that CSII with liraglutide was superior to CSII monotherapy in improving glycemic control and glycemic variability and in decreasing oxidative stress markers. Flash glucose monitoring can successfully provide ambulatory glucose profile data in the real world.

Beneficial Effects of Adiponectin on Glucose and Lipid Metabolism and Atherosclerotic Progression: Mechanisms and Perspectives

Circulating adiponectin concentrations are reduced in obese individuals, and this reduction has been proposed to have a crucial role in the pathogenesis of atherosclerosis and cardiovascular diseases associated with obesity and the metabolic syndrome. We focus on the effects of adiponectin on glucose and lipid metabolism and on the molecular anti-atherosclerotic properties of adiponectin and also discuss the factors that increase the circulating levels of adiponectin. Adiponectin reduces inflammatory cytokines and oxidative stress, which leads to an improvement of insulin resistance. Adiponectin-induced improvement of insulin resistance and adiponectin itself reduce hepatic glucose production and increase the utilization of glucose and fatty acids by skeletal muscles, lowering blood glucose levels. Adiponectin has also β cell protective effects and may prevent the development of diabetes. Adiponectin concentration has been found to be correlated with lipoprotein metabolism; especially, it is associated with the metabolism of high-density lipoprotein (HDL) and triglyceride (TG). Adiponectin appears to increase HDL and decrease TG. Adiponectin increases ATP-binding cassette transporter A1 and lipoprotein lipase (LPL) and decreases hepatic lipase, which may elevate HDL. Increased LPL mass/activity and very low density lipoprotein (VLDL) receptor and reduced apo-CIII may increase VLDL catabolism and result in the reduction of serum TG. Further, adiponectin has various molecular anti-atherosclerotic properties, such as reduction of scavenger receptors in macrophages and increase of cholesterol efflux. These findings suggest that high levels of circulating adiponectin can protect against atherosclerosis. Weight loss, exercise, nutritional factors, anti-diabetic drugs, lipid-lowering drugs, and anti-hypertensive drugs have been associated with an increase of serum adiponectin level.

Delayed Administration of the Glucagon-Like Peptide 1 Analog Liraglutide Promoting Angiogenesis after Focal Cerebral Ischemia in Mice

BACKGROUND

Glucagon-like peptide 1 (GLP-1) analogs administered before or after cerebral ischemia have been shown to provide neuroprotection. Here, we explored whether delayed administration of a GLP-1 analog, liraglutide, could improve long-term functional recovery and promote angiogenesis after stroke.

MATERIALS AND METHODS

In the present study, mice were established as a focal cerebral cortical ischemia model and were intraperitoneally administered liraglutide or normal saline (NS) daily for 14 consecutive days, starting 1 day after cerebral ischemia. The neurological deficits were evaluated using rotarod test. The microvessel density (MVD) and endothelial cell (EC) proliferation were assessed by immunohistochemical staining. The expression of vascular endothelial growth factor (VEGF) was assessed by Western blot analysis.

RESULTS

Liraglutide significantly reduced infarct volume and improved the rotarod test scores, compared with mice treated with NS. Liraglutide also greatly increased the MVD and EC proliferation and simultaneously upregulated the expression of VEGF in the cerebral ischemic area.

CONCLUSIONS

These results demonstrated that liraglutide promoted angiogenesis and long-term recovery of cerebral ischemia through increasing the expression of VEGF.

Exenatide exerts cognitive effects by modulating the BDNF-TrkB neurotrophic axis in adult mice

Modulation of insulin-dependent signaling is emerging as a valuable therapeutic tool to target neurodegeneration. In the brain, the activation of insulin receptors promotes cell growth, neuronal repair, and protection. Altered brain insulin signaling participates in the cognitive decline seen in Alzheimer's disease patients and the aging brain. Glucagon-like peptide-1 (GLP-1) regulates insulin secretion and, along with GLP-1 analogues, enhances neurotrophic signaling and counteracts cognitive deficits in preclinical models of neurodegeneration. Moreover, recent evidence indicates that GLP-1 modulates the activity of the brain-derived neurotrophic factor (BDNF). In this study, in adult wild-type mice, here employed as a model of mid-life brain aging, we evaluated the effects of a 2-month treatment with exenatide, a GLP-1 analogue. We found that exenatide promotes the enhancement of long-term memory performances. Biochemical and imaging analyses show that the drug promotes the activation of the BDNF-TrkB neurotrophic axis and inhibits apoptosis by decreasing p75NTR-mediated signaling. The study provides preclinical evidence for the use of exenatide to delay age-dependent cognitive decline.

Glucagon-Like Peptide-1 Receptor Agonists (GLP-1RAs) in the Brain-Adipocyte Axis

The complexity of neural circuits that control food intake and energy balance in the hypothalamic nuclei explains some of the constraints involved in the prevention and treatment of obesity. Two major neuronal populations present in the arcuate nucleus control caloric intake and energy expenditure: one population co-expresses orexigenic agouti-related peptide (AgRP) and neuropeptide Y and the other expresses the anorexigenic anorectic neuropeptides proopiomelanocortin and cocaine- and amphetamine-regulated transcript (POMC/CART). In addition to integrating signals from neurotransmitters and hormones, the hypothalamic systems that regulate energy homeostasis are affected by nutrients. Fat-rich diets, for instance, elicit hypothalamic inflammation (reactive activation and proliferation of microglia, a condition named gliosis). This process generates resistance to the anorexigenic hormones leptin and insulin, contributing to the genesis of obesity. Glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1RAs) have increasingly been used to treat type 2 diabetes mellitus. One compound (liraglutide) was recently approved for the treatment of obesity. Although most studies suggest that GLP-1RAs promote weight loss mainly due to their inhibitory effect on food intake, other central effects that have been described for native GLP-1 and some GLP-1RAs in rodents and humans encourage future clinical trials to explore additional mechanisms that potentially underlie the beneficial effects observed with this drug class. In this article we review the most relevant data exploring the mechanisms involved in the effects of GLP-1RAs in the brain–adipocyte axis.

Use of GLP-1 receptor agonists for type 2 diabetes treatment intensification after basal insulin failure

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are part of the armamentarium for the treatment of type 2 diabetes (T2D), although recent guidelines have mainly recommended their use on top of oral treatments when a single or combination of two or three oral hypoglycaemic agents has failed to lower HbA_1c levels below the individualized target range. In such situations, the decision to use GLP-1RAs is mostly driven by their high level of efficacy, their effect on body weight balance and their safety considerations, such as low hypoglycaemic risk. According to the current guidelines, GLP-1RAs may also be used in T2D patients in addition to basal insulin, following specialist-care advice, in patients who are more severely obese or who may not have the capacity to handle the complexities of a multiple daily injection (MDI) insulin regimen. The present review looks at the scientific evaluations performed in this context as well as the clinical trials assessing the use of GLP-1RAs in combination with intensive insulin therapy as further step-up therapy.

Exenatide Add-on to Continuous Subcutaneous Insulin Infusion Therapy Reduces Bolus Insulin Doses in Patients with Type 2 Diabetes: A Randomized, Controlled, Open-Label Trial

INTRODUCTION

The objective of this study was to investigate the effect of adding exenatide to continuous subcutaneous insulin infusion (CSII) therapy on the precise insulin doses required by type 2 diabetic patients to maintain glycemic control.

METHODS

This was a single-center, randomized, controlled, open-label trial. Uncontrolled T2D patients were recruited between March 2010 and November 2011 at Nanjing First Hospital, China. Subjects were randomly assigned (1:1) to either an exenatide add-on to CSII group or a CSII therapy only (i.e., control) group (n = 18, respectively) for 5 weeks. Patients were subjected to 3 days of continuous glucose monitoring (CGM) during the screening period and after therapy. The precise insulin doses, the times taken by the patients to achieve euglycemic control, and the mean amplitude of glycemic excursion (MAGE) at the endpoint were compared between the two groups. The primary endpoint was precise insulin dose differences between groups from baseline to the endpoint.

RESULTS

A total of 36 subjects were admitted as inpatients. Patients in the exenatide add-on therapy group needed less insulin titration time to achieve glycemic control (3.67 ± 1.33 vs. 4.78 ± 1.00 days, P = 0.028) and significantly lower bolus insulin doses than the control group at the endpoint (total bolus, 0.13 ± 0.03 vs. 0.17 ± 0.04 U/kg, P = 0.02, breakfast bolus, 0.05 ± 0.01 vs. 0.06 ± 0.01 U/kg, P = 0.01, lunch bolus, 0.04 ± 0.01 vs. 0.06 ± 0.01 U/kg, P = 0.01, dinner bolus, 0.04 ± 0.01 vs. 0.05 ± 0.01 U/kg, P = 0.01, respectively). Moreover, the CGM data showed that patients in the exenatide add-on therapy group exhibited a significant reduction in MAGE as compared to the control group (2.96 ± 1.14 vs. 4.21 ± 1.39 mmol/L, P = 0.012).

CONCLUSION

Our data suggest that adding exenatide therapy to CSII therapy leads to an improvement in glycemic excursions and the use of smaller bolus insulin doses.

TRIAL REGISTRATION

Chinese Clinical Trial Registry identifier, ChiCTR-PPR-15007045.

The role of insulin pump therapy for type 2 diabetes mellitus

Many patients with type 2 diabetes fail to achieve adequate glucose control despite escalation of treatment and combinations of multiple therapies including insulin. Patients with long-standing type 2 diabetes often suffer from the combination of severe insulin deficiency in addition to insulin resistance, thereby requiring high doses of insulin delivered in multiple injections to attain adequate glycemic control. Insulin-pump therapy was first introduced in the 1970s as an approach to mimic physiological insulin delivery and attain normal glucose in patients with type 1 diabetes. The recent years have seen an increase in the use of this technology for patients with type 2 diabetes. This article summarizes the clinical studies evaluating insulin pump use in patients with type 2 diabetes and discusses the benefits and shortcomings of pump therapy in this population. Copyright © 2016 John Wiley & Sons, Ltd.

The Neuroprotection of Liraglutide Against Ischaemia-induced Apoptosis through the Activation of the PI3K/AKT and MAPK Pathways

Glucagon-like peptide-1 (GLP-1) is an incretin hormone that increases glucose-dependent insulin secretion to reduce the glucose level. Liraglutide, a long-acting GLP-1 analogue, has been found to have neuroprotective action in various experimental models. However, the protective mechanisms of liraglutide in ischaemic stroke remain unclear. Here, we demonstrated that liraglutide significantly decreased the infarct volume, improved neurologic deficits, and lowered stress-related hyperglycaemia without causing hypoglycaemia in a rat model of middle cerebral artery occlusion (MCAO). Liraglutide inhibited cell apoptosis by reducing excessive reactive oxygen species (ROS) and improving the function of mitochondria in neurons under oxygen glucose deprivation (OGD) in vitro and MCAO in vivo. Liraglutide up-regulated the phosphorylation of protein kinase B (AKT) and extracellular signal-regulated kinases (ERK) and inhibited the phosphorylation of c-jun-NH2-terminal kinase (JNK) and p38. Moreover, the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 and/or the ERK inhibitor U0126 counteracted the protective effect of liraglutide. Taken together, these results suggest that liraglutide exerts neuroprotective action against ischaemia-induced apoptosis through the reduction of ROS and the activation of the PI3K/AKT and mitogen-activated protein kinase (MAPK) pathways. Therefore, liraglutide has therapeutic potential for patients with ischaemic stroke, especially those with Type 2 diabetes mellitus or stress hyperglycaemia.