A review of glucagon-like peptide-1 receptor agonists and their effects on lowering postprandial plasma glucose and cardiovascular outcomes in the treatment of type 2 diabetes mellitus

A Comprehensive Review of the Effects of Glycemic Carbohydrates on the Neurocognitive Functions Based on Gut Microenvironment Regulation and Glycemic Fluctuation Control

Improper glycemic carbohydrates (GCs) consumption can be a potential risk factor for metabolic diseases such as obesity and diabetes, which may lead to cognitive impairment. Although several potential mechanisms have been studied, the biological relationship between carbohydrate consumption and neurocognitive impairment is still uncertain. In this review, the main effects and mechanisms of GCs' digestive characteristics on cognitive functions are comprehensively elucidated. Additionally, healthier carbohydrate selection, a reliable research model, and future directions are discussed. Individuals in their early and late lives and patients with metabolic diseases are highly susceptible to dietary-induced cognitive impairment. It is well known that gut function is closely related to dietary patterns. Unhealthy carbohydrate diet-induced gut microenvironment disorders negatively impact cognitive functions through the gut-brain axis. Moreover, severe glycemic fluctuations, due to rapidly digestible carbohydrate consumption or metabolic diseases, can impair neurocognitive functions by disrupting glucose metabolism, dysregulating calcium homeostasis, oxidative stress, inflammatory responses, and accumulating advanced glycation end products. Unstable glycemic status can lead to more severe neurological impairment than persistent hyperglycemia. Slow-digested or resistant carbohydrates might contribute to better neurocognitive functions due to stable glycemic response and healthier gut functions than fully gelatinized starch and nutritive sugars.

Beyond the Cardiovascular Effects of Glucagon-like Peptide-1 Receptor Agonists: Body Slimming and Plaque Stabilization. Are New Statins Born?

Atherosclerosis is a chronic inflammatory disease characterized by lipid and inflammatory cell deposits in the inner layer of large- and medium-sized elastic and muscular arteries. Diabetes mellitus (DM) significantly increases the risk of cardiovascular diseases and the overall and cardiovascular mortality, and it is a pro-atherogenic factor that induces atherosclerosis development and/or accelerates its progression through a multifactorial process. Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are a new class of drugs, belonging to the armamentarium to fight type 2 DM, that have shown robust reductions in atherosclerotic events and all-cause mortality in all studies. Preclinical studies have shown that GLP-1RAs play a role in the immunomodulation of atherosclerosis, affecting multiple pathways involved in plaque development and progression. In this review, we wanted to explore the translational power of such preclinical studies by analyzing the most recent clinical trials investigating the atheroprotective effect of GLP-1RAs.

Glycaemic variabilities: Key questions in pursuit of clarity

After years of intensive investigation, the definition of glycaemic variability remains unclear and the term variability in glucose homoeostasis might be more appropriate covering both short and long-term glycaemic variability. For the latter, we remain in the search of an accurate definition and related targets. Recent work leads us to consider that the within-subject variability of HbA1c calculated from consecutive determinations of HbA1c at regular time-intervals could be the most relevant index for assessing the long-term variability with a threshold value of 5% (%CV = SD of HbA1c/mean HbA1c) to separate stability from lability of HbA1c. Presently, no one can deny that short- and long-term glucose variability should be maintained within their lower ranges to limit the incidence of hypoglycaemia. Usually, therapeutic strategies aimed at reducing post-meal glucose excursions, i.e. the major contributor to daily glucose fluctuations, exert a beneficial effect on the short-term glucose variability. This explains the effectiveness of adjunct therapies with either GLP- receptor agonists or SGLT inhibitors in type 2 diabetes. In type 1 diabetes, the application of a CGM device alone reduces the short-term glycaemic variability. In contrast, sophisticated insulin delivery does not necessarily lead to such reductions despite marked downward shifts of 24-hour glycaemic profiles. Such contrasting observations raise the question as to whether the prolonged wear of CGM devices is or not the major causative factor for improvement in glucose variability among intensively insulin-treated persons with type 1 diabetes.

Glycaemic and non-glycaemic efficacy of once-weekly GLP-1 receptor agonists in people with type 2 diabetes

WHAT IS KNOWN AND OBJECTIVE

Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) may confer a range of benefits for people with type 2 diabetes (T2D), which is reflected through their position within diabetes treatment guidelines. The objective of this narrative review is to explore the efficacy data of once-weekly (QW) GLP-1 RAs in terms of glycaemic control, body weight reduction, cardiovascular (CV) outcomes and potential renal protective effects to assist pharmacists and other healthcare professionals (HCPs) in treatment discussions with patients.

METHODS

This a narrative review focused on 31 clinical trials involving the Phase 3 clinical programmes of the QW GLP-1 RAs dulaglutide, exenatide extended-release (ER) and semaglutide subcutaneous (s.c.).

RESULTS AND DISCUSSION

The clinical trials were divided by their comparator arms and examined for trends. All QW GLP-1 RAs were superior to placebo for reductions in glycated haemoglobin (HbA_1c ) and body weight. Data regarding QW GLP-1 RAs versus metformin were limited, likely due to metformin's use as the first-line pharmacologic for T2D. In the robust head-to-head trials of QW versus QW GLP-1 RAs, semaglutide s.c. was superior to both dulaglutide and exenatide ER regarding HbA_1c and body weight; however, QW versus once-daily GLP-1 RA trials had mixed results depending on the comparators. Finally, in QW GLP-1 RA versus insulin trials, all QW GLP-1 RAs were as effective as insulin, particularly when hypoglycaemia and body weight were also considered. CV outcome trials demonstrated benefits in major adverse CV events and renal outcomes for semaglutide and dulaglutide.

WHAT IS NEW AND CONCLUSION

This review collates recently published data and previously published Phase 3 results to allow pharmacists and other HCPs to understand all of the efficacy data available and the corresponding impact on treatment guidelines. QW GLP-1 RAs are emerging as important therapeutic options for people with T2D as they offer a spectrum of benefits extending beyond glycaemic control, but it is important to be aware of their efficacy differences when prescribing and discussing them with patients.

miR-381-3p inhibits high glucose-induced vascular smooth muscle cell proliferation and migration by targeting HMGB1

BACKGROUND

Hyperglycemia increases the risk of many cardiovascular diseases (CVD), and the dysregulation of proliferation and migration in vascular smooth muscle cells (VSMCs) also participates in the pathogenesis of CVD. miR-381-3p is known to suppress the proliferation and migration of multiple human cell types. Nevertheless, the function of miR-381-3p in VSMCs remains largely indistinct.

METHODS

A quantitative real-time polymerase chain reaction (qRT-PCR) was employed to investigate miR-381-3p expression in high-glucose-induced VSMCs. Inflammatory cytokines tumor necrosis factor-α, interleukin-1β and interleukin-6, as well as oxidative stress markers SOD and MDA, were determined by an enzyme-linked immunosorbent assay. Reactive oxygen species generation was examined using a 2,7'-dichlorofluorescein kit. The proliferation, migration and apoptosis of VSMCs were monitored by 3-(4,5-dimethylthiazl2-yl)-2,5-diphenyltetazolium bromide (MTT), transwell and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assays. The TargetScan database (http://www.targetscan.org) was employed to seek the potential target gene of miR-381-3p. Interaction between miR-381-3p and HMGB1 was determined by a qRT-PCR, western blotting and a luciferase reporter assay.

RESULTS

miR-381-3p expression was significantly reduced in a VSMCs dysfunction model induced by high-glucose in a dose- and time-dependent manner. Transfection of miR-381-3p mimics suppressed the inflammation, oxidative stress, proliferation and migration of VSMCs, whereas apoptosis of VSMCs was promoted, and the transfection of miR-381-3p inhibitors had the opposite effect. Mechanistically, HMGB1, an important factor in inflammation response, was confirmed as a target gene of miR-381-3p.

CONCLUSIONS

miR-381-3p targets HMGB1 to suppress the inflammation, oxidative stress, proliferation and migration of high-glucose-induced VSMCs by targeting HMGB1.

Liraglutide Attenuates Myocardial Fibrosis via Inhibition of AT1R-Mediated ROS Production in Hypertensive Mice

BACKGROUND/AIMS

Glucagon-like peptide-1 receptor agonist liraglutide has been reported to exert cardioprotective effects, but its effect on cardiac fibrosis remains controversial. The aim of this study was to investigate the effects of liraglutide on cardiac fibrosis and potential mechanisms.

METHODS

C57BL/6 mice (3-month old) were randomly divided into control, hypertension, and hypertension + liraglutide groups. The hypertensive state was created by infusion of Ang II (100 ng/kg·min) for 4 weeks through subcutaneously implanted osmotic pumps. The control mice were infused with saline. Mice were also given vehicle or liraglutide (400 μg/kg·day). Blood pressure (BP), blood sugar, myocardial fibrosis, AT1R expression, and reactive oxygen species (ROS) levels were measured. To further elucidate the mechanisms of fibrosis, mouse cardiac fibroblasts were isolated and treated with liraglutide (300 nM/L) or losartan (10 μM) for 3 hours, followed by Ang II (10^-7 M) for additional 12 hours. Reactive oxygen species production and expressions of collagen-1 and -3 were measured.

RESULTS

Liraglutide reduced BP and blood sugar but did not affect the body weight of the hypertensive mice. Liraglutide also inhibited collagen accumulation, AT1R expression, and ROS generation in the hearts of the hypertensive mice. In in vitro studies, pretreatment with liraglutide and losartan (as control) markedly inhibited Ang II-induced ROS production and collagen expression in the cultured cardiac fibroblasts.

CONCLUSION

Liraglutide reduces myocardial fibrosis in the hypertensive mice, which appears to be dependent on at least in part inhibition of ROS production.

Association of GLP-1 receptor gene polymorphisms with sporadic Parkinson's disease in Chinese Han population

The Glucagon Like Peptide 1 Receptor (GLP1R) plays a critical role in selective death of dopaminergic neurons and development of Parkinson's disease (PD). However, little is known about genetic associations of GLP1R gene polymorphisms with PD susceptibility. Therefore, this study aimed to verify whether GLP1R polymorphisms contribute to PD risk in a Chinese Han population. We recruited 518 individuals comprising 259 sporadic PD patients and 259 healthy controls. All of the participants were genotyped for two possibly functional polymorphisms located in GLP1R (rs3765467 and rs6923761) using the Sequenom MassARRAY platform. The frequency of the rs3765467 GG genotype was significantly higher in the PD group compared with that in the control group (OR = 1.444, 95 % CI: 1.015-2.055, p =  0.041). Subgroup analysis revealed that male patients and late-onset patients with the rs3765467 GG genotype suffered an increased risk of PD compared with healthy controls (p =  0.021 and p =  0.012, respectively). However, the genotype and allele frequencies for rs6923761 were not significantly different between PD and healthy subjects. Our results indicate that the GLP1R rs3765467 GG genotype is a potential risk factor for PD, especially for male and late-onset PD patients in the Chinese Han population.

Time to Insulin Initiation in Type 2 Diabetes Patients in 2010/2011 and 2016/2017 in Germany

BACKGROUND

The aim of the current study was to determine whether the time to insulin therapy initiation in patients with type 2 diabetes in primary care in Germany has changed in recent years.

METHODS

Longitudinal data from general practices in Germany (Disease Analyzer) were analyzed. These data included information of 7128 patients (age: 68.5 [SD: 11.5] years; 54.4% male) receiving incident insulin therapy in 2010/2011 and 8216 patients (age: 69.1 [SD: 11.9] years; 54.9% male) receiving incident insulin therapy in 2016/2017. Changes in time to insulin initiation in the practices and the last HbA1c value before the start of insulin therapy were analyzed, stratified by index date. To analyze the impact of covariables on the time to insulin initiation, a multivariate regression analysis was performed, adjusted for age, sex, diabetologist care, and HbA1c as independent variables.

RESULTS

Median time from T2D diagnosis to insulin therapy in the Disease Analyzer database increased from 1717 days in 2010/2011 to 1917 days in 2016/2017 (P < .001). The proportion of patients with a HbA1c value ≥9% before insulin initiation was high in both groups (2010/2011: 33.0%, 2016/2017: 34.2%, P = .347). The time to insulin initiation in DPP-4i patients was 112 days longer, and in SGLT2 patients 346 days longer than in patients treated with sulfonylurea.

CONCLUSIONS

The present analysis confirms an increasing delay of the insulin therapy initiation as a consequence of the more frequent use of newer oral antidiabetics. However, the rather moderate increase of time to insulin might display insufficient long-term glycemic control using these agents. Still, more than one-third of patients receive insulin only when HbA1c levels exceed 9%.

GLP-1 Receptor Agonists for Type 2 Diabetes and Their Role in Primary Care: An Australian Perspective

The ever-increasing number of drugs available to treat type 2 diabetes and the complexity of patients with this condition present a constant challenge when it comes to identifying the most appropriate treatment approach. The more recent glucagon-like peptide-1 receptor agonists (GLP-1RAs) are non-insulin injectable options for the management of type 2 diabetes. Effective at improving glycaemic control with a low intrinsic risk of hypoglycaemia and the potential for weight reduction, this agent class is an important addition to the prescribing armamentarium. However, understanding their place in therapy may prove confusing for many primary care practitioners, especially given the common belief that 'injectables' are a last-resort treatment option, which puts them at risk of being niched alongside insulin. This review summarises the clinical evidence for GLP-1RAs and how they compare to other glucose-lowering agents in managing type 2 diabetes. It also provides practical and case-driven opinions and recommendations on the optimal use of GLP-1RAs by discussing important patient factors and clinical considerations that will help to identify those who are most likely to benefit from this class of agents.Funding: Eli Lilly Australia.

Importance of Postprandial Glucose in Relation to A1C and Cardiovascular Disease

IN BRIEF This article reviews the evidence regarding the impact of postprandial glucose (PPG) on overall A1C and its relation to cardiovascular disease (CVD). To date, four randomized, controlled trials have evaluated the impact of PPG reduction on CVD; however, only one of these successfully demonstrated a positive effect. Despite this, epidemiological evidence does indicate a cardiovascular benefit of PPG reduction, and agents that can be used to manage PPG in people with type 2 diabetes are also discussed.

Canagliflozin: A Review in Type 2 Diabetes

Canagliflozin (Invokana^®) is a sodium-glucose co-transporter-2 (SGLT2) inhibitor indicated in various countries worldwide for the once-daily oral treatment of type 2 diabetes (T2D). Canagliflozin lowers blood glucose levels independently of insulin, with the inhibition of SGLT2 reducing renal reabsorption of glucose and increasing excretion of glucose in the urine. In well-designed clinical trials, canagliflozin (as first-line monotherapy or add-on therapy to other antihyperglycaemic agents) improved glycaemic control in adults with T2D, including those of older age and/or at high cardiovascular (CV) risk, and also had beneficial effects on their bodyweight and blood pressure (BP). CV risk reduction, as well as possible renal benefits, were also seen with canagliflozin in T2D patients at high CV risk in the CANVAS Program, an integrated analysis of two large CV outcomes studies. Canagliflozin was generally well tolerated, had a low risk of hypoglycaemia and was most commonly associated with adverse events such as genital and urinary tract infections and increased urination, consistent with its mechanism of action. Although the amputation and fracture risk observed among recipients of the drug require further investigation, canagliflozin is an important option for T2D management in adults.

Role of Intestinal Bitter Sensing in Enteroendocrine Hormone Secretion and Metabolic Control

The gastrointestinal tract stores ingested nutrients in the stomach which are then delivered to the small intestine at a controlled rate to optimize their digestion and absorption. The interaction of nutrients with the small and large intestine generates feedback that slows gastric emptying, induces satiation, and reduces postprandial glycemic excursions. The mechanisms underlying these nutrient-gut interactions are complex; it has only recently been appreciated that the gut has the capacity to detect intraluminal contents in much the same way as the tongue, via activation of specific G-protein-coupled receptors, and that ensuing signaling mechanisms modulate the release of an array of gut hormones that influence gastrointestinal motility, appetite and glycemia. Interestingly, evidence from preclinical models supports a functional link between intestinal bitter taste receptor (BTRs) and gastrointestinal hormone secretion, and the outcomes of recent studies indicate that stimulation of intestinal BTRs may be used to modulate gastrointestinal function, to diminish energy intake and limit postprandial blood glucose excursions in humans. This review summarizes current evidence about the expression and function of intestinal BTRs in relation to enteroendocrine hormone release and discusses the clinical implications of this pathway for the management of obesity and type 2 diabetes.

Bidirectional Relationship between Gastric Emptying and Plasma Glucose Control in Normoglycemic Individuals and Diabetic Patients

Gastric emptying and glycemic control pathways are closely interrelated processes. Gastric chyme is transferred into the duodenum with velocities depending on its solid or liquid state, as well as on its caloric and nutritional composition. Once nutrients enter the intestine, the secretion of incretins (hormonal products of intestinal cells) is stimulated. Among incretins, glucagon-like peptide-1 (GLP-1) has multiple glycemic-regulatory effects that include delayed gastric emptying, thus triggering a feedback loop lowering postprandial serum glucose levels. Glycemic values also influence gastric emptying; hyperglycemia slows it down, and hypoglycemia accelerates it, both limiting glycemic fluctuations. Disordered gastric emptying in diabetes mellitus is understood today as a complex pathophysiological condition, with both irreversible and reversible components and high intra- and interindividual variability of time span and clinical features. While limited delays may be useful for reducing postprandial hyperglycemias, severely hindered gastric emptying may be associated with higher glycemic variability and worsened long-term glycemic control. Therapeutic approaches for both gastric emptying and glycemic control include dietary modifications of meal structure or content and drugs acting as GLP-1 receptor agonists. In the foreseeable future, we will probably witness a wider range of dietary interventions and more incretin-based medications used for restoring both gastric emptying and glycemic levels to nearly physiological levels.

Adding prandial GLP-1 receptor agonists to basal insulin: a promising option for type 2 diabetes therapy

BACKGROUND

Diabetes mellitus is a serious and increasingly prevalent condition in Canada and around the world. Treatment strategies have become increasingly complex, with a widening array of pharmacological agents available for glycemic management in type 2 diabetes mellitus (T2DM). New therapies that act in concert with available basal insulins may represent alternatives to basal insulin intensification with prandial or pre-mixed insulin. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) have recently shown promise as useful additions to basal insulin, with significant reductions in glycated hemoglobin and potentially beneficial effects on body weight. This review will focus on pivotal clinical trials to assess the potential benefits of adding prandial GLP-1 RAs to basal insulin in patients with T2DM.

METHODS

Clinical studies combining prandial GLP-1 RAs and basal insulin (published between 2011 and July 2017) were identified and reviewed in PubMed, the Cochrane Central Register of Clinical Trials (Issue 6, June 2017), and clinicaltrials.gov.

RESULTS

Most of the studies presented in this review show that the addition of a prandial GLP-1 RA to basal insulin results in equal or slightly superior efficacy compared to the addition of prandial insulin, together with weight loss and less hypoglycemia.

CONCLUSIONS

The results of the studies suggest that a prandial GLP-1 RA as an add-on to basal insulin may be a safe and effective treatment intensification option (vs basal-plus or basal-bolus insulin).

A review of glucagon-like peptide-1 receptor agonists and their effects on lowering postprandial plasma glucose and cardiovascular outcomes in the treatment of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is an independent risk factor for cardiovascular (CV) comorbidities, with CV disease being the most common cause of death in adults with T2DM. Although glucocentric therapies may improve glycaemic control (as determined by glycated haemoglobin levels), evidence suggests that this approach alone has limited beneficial effects on CV outcomes relative to improvements in lipid and blood pressure control. This may be explained in part by the fact that current antidiabetic treatment regimens primarily address overall glycaemia and/or fasting plasma glucose, but not the postprandial plasma glucose (PPG) excursions that have a fundamental causative role in increasing CV risk. This literature review evaluates the relationship between PPG and the risk of CV disease, discusses the treatment of T2DM with glucagon-like peptide-1 receptor agonists (GLP-1 RAs) and examines the associated CV outcomes. The literature analysis suggests that exaggerated PPG excursions are a risk factor for CV disease because of their adverse pathophysiologic effects on the vasculature, resulting in increased all-cause and CV-related mortality. Although GLP-1 RAs are well established in the current T2DM treatment paradigm, a subgroup of these compounds has a particularly pronounced, persistent and short-lived effect on gastric emptying and, hence, lower PPG substantially. However, current long-term data on CV outcomes with GLP-1 RAs are contradictory, with both beneficial and adverse effects having been reported. This review explores the opportunity to direct treatment towards controlling PPG excursions, thereby improving not only overall glycaemic control but also CV outcomes.