Interim analysis of the effects of exenatide treatment on A1C, weight and cardiovascular risk factors over 82 weeks in 314 overweight patients with type 2 diabetes

Long-term changes in cardiovascular risk markers during administration of exenatide twice daily or glimepiride: results from the European exenatide study

OBJECTIVE

The risk of cardiovascular morbidity and mortality is significantly increased in patients with diabetes; thus, it is important to determine whether glucose-lowering therapy affects this risk over time. Changes in cardiovascular risk markers were examined in patients with type 2 diabetes treated with exenatide twice daily (a glucagon-like peptide-1 receptor agonist) or glimepiride (a sulfonylurea) added to metformin in the EURopean EXenAtide (EUREXA) study.

RESEARCH DESIGN AND METHODS

Patients with type 2 diabetes failing metformin were randomized to add-on exenatide twice daily (n = 515) or glimepiride (n = 514) until treatment failure defined by hemoglobin A1C. Anthropomorphic measures, blood pressure (BP), heart rate, lipids, and high-sensitivity C-reactive protein (hsCRP) over time were evaluated.

RESULTS

Over 36 months, twice-daily exenatide was associated with improved body weight (-3.9 kg), waist circumference (-3.6 cm), systolic/diastolic BP (-2.5/-2.6 mmHg), high-density lipoprotein (HDL)-cholesterol (0.05 mmol/L), triglycerides (-0.2 mmol/L), and hsCRP (-1.7 mg/L). Heart rate did not increase (-0.3 beats/minute), and low-density lipoprotein-cholesterol (0.2 mmol/L) and total cholesterol (0.1 mmol/L) increased slightly. Between-group differences were significantly in favor of exenatide for body weight (P < 0.0001), waist circumference (P < 0.001), systolic BP (P < 0.001), diastolic BP (P = 0.023), HDL-cholesterol (P = 0.001), and hsCRP (P = 0.004). Fewer patients randomized to exenatide twice daily versus glimepiride required the addition of at least one antihypertensive (20.4 vs 26.4%; P = 0.026) or lipid-lowering medication (8.4 vs 12.8%; P = 0.025).

CONCLUSIONS

Add-on exenatide twice daily was associated with significant, sustained improvement in several cardiovascular risk markers in patients with type 2 diabetes versus glimepiride.

CLINICAL TRIAL REGISTRATION

NCT00359762, http://www.ClinicalTrials.gov.

Comparison Review of Short-Acting and Long-Acting Glucagon-like Peptide-1 Receptor Agonists

Glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1 RAs) are useful tools for treating type 2 diabetes mellitus. In their recent position statement, the American Diabetes Association and European Association for the Study of Diabetes recommend GLP1-RAs as add-on to metformin when therapeutic goals are not achieved with monotherapy, particularly for patients who wish to avoid weight gain or hypoglycemia. GLP1-RAs differ substantially in their duration of action, frequency of administration and clinical profile. Members of this class approved for clinical use include exenatide twice-daily, exenatide once-weekly, liraglutide and lixisenatide once-daily. Recently, two new once-weekly GLP1-RAs have been approved: dulaglutide and albiglutide. This article summarizes properties of short- and long-acting GLP-1 analogs, and provides useful information to help choose the most appropriate compound for individual patients.

Unintended positive and negative effects of drugs on lipoproteins

PURPOSE OF REVIEW

Dyslipidaemia is an important cardiovascular disease risk factor. Many drugs affect lipid profile and lipoprotein metabolism. We reviewed unintended effects of nonlipid modifying, commonly used medications on lipid profile and lipoprotein metabolism.

RECENT FINDING

Several detrimental effects of many drug classes such as diuretics, antidepressant, anticonvulsant and antiretroviral drugs have been reported, whereas other drug classes such as antiobesity, alpha 1-blockers, oestrogens and thyroid replacement therapy were associated with positive effects.

SUMMARY

Dyslipidaemia is a common side-effect of many medications. This should be taken into consideration, especially in patients at high risk of cardiovascular disease. Other drugs demonstrated positive effects on circulating lipids and lipoproteins. The impact of these unintended effects on atherosclerotic disease risk and progression is unclear.

Cardiovascular Risk in Diabetes Mellitus: Complication of the Disease or of Antihyperglycemic Medications

Cardiovascular disease is the principal complication and the leading cause of death for patients with diabetes (DM). The efficacy of antihyperglycemic treatments on cardiovascular disease risk remains uncertain. Cardiovascular risk factors are affected by antihyperglycemic medications, as are many intermediate markers of cardiovascular disease. Here we summarize the evidence assessing the cardiovascular effects of antihyperglycemic medications with regard to risk factors, intermediate markers of disease, and clinical outcomes.

Impact of glucose-lowering drugs on cardiovascular disease in type 2 diabetes

Type 2 diabetes mellitus (T2DM) is characterized by multiple pathophysiologic abnormalities. With time, multiple glucose-lowering medications are commonly required to reduce and maintain plasma glucose concentrations within the normal range. Type 2 diabetes mellitus individuals also are at a very high risk for microvascular complications and the incidence of heart attack and stroke is increased two- to three-fold compared with non-diabetic individuals. Therefore, when selecting medications to normalize glucose levels in T2DM patients, it is important that the agent not aggravate, and ideally even improve, cardiovascular risk factors (CVRFs) and reduce cardiovascular morbidity and mortality. In this review, we examine the effect of oral (metformin, sulfonylureas, meglitinides, thiazolidinediones, DPP4 inhibitors, SGLT2 inhibitors, and α-glucosidase inhibitors) and injectable (glucagon-like peptide-1 receptor agonists and insulin) glucose-lowering drugs on established CVRFs and long-term studies of cardiovascular outcomes. Firm evidence that in T2DM cardiovascular disease can be reversed or prevented by improving glycaemic control is still incomplete and must await large, long-term clinical trials in patients at low risk using modern treatment strategies, i.e., drug combinations designed to maximize HbA1c reduction while minimizing hypoglycaemia and excessive weight gain.

Pathophysiological mechanisms involved in non-alcoholic steatohepatitis and novel potential therapeutic targets

Non-alcoholic fatty liver disease (NAFLD) is a major health care problem and represents the hepatic expression of the metabolic syndrome. NAFLD is classified as non-alcoholic fatty liver (NAFL) or simple steatosis, and non-alcoholic steatohepatitis (NASH). NASH is characterized by the presence of steatosis and inflammation with or without fibrosis. The physiopathology of NAFL and NASH and their progression to cirrhosis involve several parallel and interrelated mechanisms, such as, insulin resistance (IR), lipotoxicity, inflammation, oxidative stress, and recently the gut-liver axis interaction has been described. Incretin-based therapies could play a role in the treatment of NAFLD. Glucagon-like peptide-1 (GLP-1) is an intestinal mucosa-derived hormone which is secreted into the bloodstream in response to nutrient ingestion; it favors glucose-stimulated insulin secretion, inhibition of postprandial glucagon secretion and delayed gastric emptying. It also promotes weight loss and is involved in lipid metabolism. Once secreted, GLP-1 is quickly degraded by dipeptidyl peptidase-4 (DPP-4). Therefore, DPP-4 inhibitors are able to extend the activity of GLP-1. Currently, GLP-1 agonists and DPP-4 inhibitors represent attractive options for the treatment of NAFLD and NASH. The modulation of lipid and glucose metabolism through nuclear receptors, such as the farsenoid X receptor, also constitutes an attractive therapeutic target. Obeticholic acid is a potent activator of the farnesoid X nuclear receptor and reduces liver fat content and fibrosis in animal models. Ursodeoxycholic acid (UDCA) is a hydrophilic bile acid with immunomodulatory, anti-inflammatory, antiapoptotic, antioxidant and anti-fibrotic properties. UDCA can improve IR and modulate lipid metabolism through its interaction with nuclear receptors such as, TGR5, farnesoid X receptor-α, or the small heterodimeric partner. Finally, pharmacologic modulation of the gut microbiota could have a role in the therapy of NAFLD and NASH. Probiotics prevent bacterial translocation and epithelial invasion, inhibit mucosal adherence by bacteria, and stimulate host immunity. In animal models, probiotics prevent obesity, decrease transaminase levels, and improve IR and liver histology in NASH.

Recent Advances in Dipeptidyl-Peptidase-4 Inhibition Therapy: Lessons from the Bench and Clinical Trials

DPP4 inhibitors (DPP4i) are a class of newly developed antidiabetic drugs which preserve incretin hormones and promote postprandial insulin secretion. Although the cardiovascular effect of DPP4 inhibition has been substantially studied, the exact role of DPP4 in cardiovascular disease especially in humans remains elusive. Previous small studies and meta-analyses have suggested a benefit in both surrogate outcomes and cardiovascular events for these agents. However, there was growing evidence in recent years questioning the cardioprotective effect of DPP4i. Further, a signal of heart failure hospitalization in a recent large scale clinical trial SAVOR-TIMI 53 has called into question the safety of these agents and their utility in the treatment of cardiovascular disease. In this review, we will revisit the physiologic function of DPP4 and discuss its role in cardiometabolic disease based on recent experimental and clinical studies.

Implications of incretin-based therapies on cardiovascular disease

BACKGROUND

Incretin-based therapies offer another treatment option for patients with type 2 diabetes. Agents that provide glycaemic control in addition to attenuating cardiovascular disease (CVD) risk factors are important for diabetes management. This review will focus on the off-target effects of incretin-based therapies on CVD risk factors [body weight, blood pressure (BP), lipid profile and albuminuria], major adverse cardiovascular events (MACE), heart failure (HF) and beta-cell preservation.

METHODS

A literature search was conducted to identify English-language publications for incretin-based therapies evaluating the following off-target end-points: body weight, BP, lipid profile, albuminuria, MACE, HF and beta-cell function. Randomised controlled trials (RCTs) were prioritised as the primary source of information.

RESULTS

Overall, incretin-based therapies have shown beneficial effects on CVD risk factors, and glucagon-like peptide 1 (GLP-1) receptor agonists appear to have a more pronounced effect compared with dipeptidyl peptidase-4 inhibitors. RCTs are being conducted to determine if these positive effects on CVD risk factors translate to a reduction in MACE. To date, these studies have not shown an increase in MACE. A signal of increased hospitalisations for HF was observed with saxagliptin, warranting continued evaluation and vigilance in high-risk patients. In addition, incretin-based therapies have shown positive effects on measures of beta-cell function supporting their durability in the management of diabetes.

CONCLUSIONS

Incretin-based therapies are an important treatment option for patients with type 2 diabetes, offering beneficial effects on CVD risk factors without increasing MACE.

Association among weight change, glycemic control, and markers of cardiovascular risk with exenatide once weekly: a pooled analysis of patients with type 2 diabetes

Background

Overweight or obesity contributes to the development of type 2 diabetes mellitus (T2DM) and increases cardiovascular risk. Exenatide, a glucagon-like peptide-1 receptor agonist, significantly reduces glycated hemoglobin (A1C) and body weight and improves cardiovascular risk markers in patients with T2DM. As weight loss alone has been shown to reduce A1C and cardiovascular risk markers, this analysis explored whether weight loss contributed importantly to clinical responses to exenatide once weekly.

Methods

A pooled analysis from eight studies of exenatide once weekly was conducted. Patients were distributed into quartiles from greatest weight loss (Quartile 1) to least loss or gain (Quartile 4). Parameters evaluated for each quartile included A1C, fasting plasma glucose (FPG), blood pressure (BP), heart rate, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), total cholesterol, triglycerides, and the liver enzymes alanine aminotransferase (ALT) and aspartate aminotransferase (AST).

Results

The median changes from baseline in body weight in Quartiles 1–4 were −6.0, –3.0, −1.0, and +1.0 kg, respectively. All quartiles had reductions in A1C (median changes −1.6, −1.4, −1.1, and −1.2%, respectively) and FPG (−41, −40, −31, and −25 mg/dL, respectively), with the greatest decreases in Quartiles 1 and 2. Most cardiovascular risk markers (except diastolic BP) and liver enzymes improved in Quartiles 1 through 3 and were relatively unchanged in Quartile 4. Higher rates of gastrointestinal adverse events and hypoglycemia were observed in Quartile 1 compared with Quartiles 2 through 4.

Conclusions

Exenatide once weekly improved glycemic parameters independent of weight change, although the magnitude of improvement increased with increasing weight loss. The greatest trend of improvement in glycemic parameters, cardiovascular risk factors including systolic BP, LDL-C, total cholesterol, and triglycerides, and in liver enzymes, was seen in the patient quartiles with the greatest reductions in body weight.

Efficacy and tolerability of glucagon-like peptide-1 receptor agonists in patients with type 2 diabetes mellitus

Glucagon-like peptide-1 (GLP-1) has been evaluated for use in the treatment of type 2 diabetes mellitus (T2DM) due to its role in glucose regulation. Four GLP-1 receptor agonists (RAs) are currently indicated for T2DM in the USA. Exenatide and liraglutide are short-acting and require twice-daily and daily dosing, respectively. Two longer acting agents, exenatide long-acting release (LAR) and albiglutide, were formulated to allow for once-weekly dosing. All four GLP-1 RAs have demonstrated reductions in hemoglobin A1c, fasting blood glucose, and body weight both as monotherapy and in combination with first- and second-line diabetes agents including metformin, sulfonylureas, thiazolidinediones, and insulin. Greater glycemic control was seen with liraglutide compared with the other GLP-1 treatment options; however, the two long-acting agents were superior to exenatide twice daily. All agents were well tolerated with most adverse events being mild or moderate in nature. The most common adverse event was transient nausea which typically resolved 4-8 weeks after treatment initiation. Long-acting agents had lower rates of nausea but an increased incidence of injection site reactions. Trials have suggested GLP-1 RAs may improve cardiovascular risk factors including blood pressure, lipid parameters and inflammatory markers. Future trials are needed to confirm the clinical outcomes of these agents. Overall, GLP-1 RAs will provide benefit for patients with T2DM intolerable to or not reaching glycemic goals with first-line agents, especially in patients in need of weight loss.

Expression of Glucagon-Like Peptide 1 Receptor during Osteogenic Differentiation of Adipose-Derived Stem Cells

BACKGROUND

Glucagon-like peptide 1 (GLP-1), an incretin hormone well known for its glucose-lowering effect, was recently reported to exert an anabolic effect on bone. Although the exact mechanism is not known, it likely involves the GLP-1 receptor (GLP-1R), which is expressed in some osteoblastic cell lines. Adipose-derived stem cells (ADSCs) have mesenchymal stem cell-specific characteristics, including osteoblastic differentiation potential. We evaluated the expression of GLP-1R during osteogenic differentiation of ADSCs.

METHODS

ADSCs were isolated from subcutaneous adipose tissue obtained from three male donors during plastic surgery and were subjected to osteogenic induction. Mineralization was assessed by Alizarin Red staining on day 21. Expression of alkaline phosphatase (ALP), osteocalcin (OC), and GLP-1R was measured by real-time polymerase chain reaction in triplicate for each patient on days 0, 7, 14, and 21. Target mRNA expression levels were normalized to that of β-actin.

RESULTS

ADSCs were fibroblast-like in morphology, adhered to plastic, and had multipotent differentiation potential, as assessed using specific antigen markers. The osteogenic markers ALP and OC were notably upregulated at 21 days. Osteogenic differentiation resulted in a time-dependent increase in the expression of GLP-1R (P=0.013).

CONCLUSION

We demonstrated upregulation of GLP-1R gene expression during osteogenic differentiation of ADSCs. This finding suggests that GLP-1 may induce osteogenic differentiation in bone tissue.

Effects of glucagon-like peptide-1 agents on left ventricular function: systematic review and meta-analysis

BACKGROUND

The cardiovascular safety of many glucagon-like peptide-1 agents (GLP-1 agents) is unclear. In this study, we assess the effects of the GLP-1 agents on left ventricular function in patients with type 2 diabetes (T2DM) and/or cardiovascular disease (CVD).

METHODS

PubMed, EMBASE, and the Cochrane Library were searched for the relevant publications up to May 2013 without restriction by language. All clinical controlled trials assessing left ventricular function and cardiovascular outcomes with the GLP-1 agents were selected for eligibility. Fourteen trials (415 patients) were identified as eligible between 1966 and 2013. Twelve of the studies were randomized controlled trials (RCT).

RESULTS

The results showed that GLP-1 agent treatment in patients with T2DM and/or CVD led to significantly improved regional left ventricular contractile parameters (including peak left systolic tissue velocity and strain) and global left ventricular performance (including stroke volume, ejection fraction, and left ventricular chambers) compared with patients receiving placebo.

CONCLUSIONS

GLP-1 agent treatment in T2DM and/or CVD patients is associated with a modest but significant increase in the odds of left ventricular contractile parameters and left ventricular performance compared with patients having received placebo, which may be indicative of additional cardiovascular benefits for these patients.

Cannabinoid receptor 1 antagonist treatment induces glucagon release and shows an additive therapeutic effect with GLP-1 agonist in diet-induced obese mice

Cannabinoid 1 (CB1) receptor antagonists reduce body weight and improve insulin sensitivity. Preclinical data indicates that an acute dose of CB1 antagonist rimonabant causes an increase in blood glucose. A stable analog of glucagon-like peptide 1 (GLP-1), exendin-4 improves glucose-stimulated insulin secretion in pancreas, and reduces appetite through activation of GLP-1 receptors in the central nervous system and liver. We hypothesized that the insulin secretagogue effect of GLP-1 agonist exendin-4 may synergize with the insulin-sensitizing action of rimonabant. Intraperitoneal as well as intracerebroventricular administration of rimonabant increased serum glucose upon glucose challenge in overnight fasted, diet-induced obese C57 mice, with concomitant rise in serum glucagon levels. Exendin-4 reversed the acute hyperglycemia induced by rimonabant. The combination of exendin-4 and rimonabant showed an additive effect in the food intake, and sustained body weight reduction upon repeated dosing. The acute efficacy of both the compounds was additive for inducing nausea-like symptoms in conditioned aversion test in mice, whereas exendin-4 treatment antagonized the effect of rimonabant on forced swim test upon chronic dosing. Thus, the addition of exendin-4 to rimonabant produces greater reduction in food intake owing to increased aversion, but reduces the other central nervous system side effects of rimonabant. The hyperglucagonemia induced by rimonabant is partially responsible for enhancing the antiobesity effect of exendin-4.

GLP-1 receptor agonism ameliorates hepatic VLDL overproduction and de novo lipogenesis in insulin resistance

BACKGROUND/OBJECTIVES

Fasting dyslipidemia is commonly observed in insulin resistant states and mechanistically linked to hepatic overproduction of very low density lipoprotein (VLDL). Recently, the incretin hormone glucagon-like peptide-1 (GLP-1) has been implicated in ameliorating dyslipidemia associated with insulin resistance and reducing hepatic lipid stores. Given that hepatic VLDL production is a key determinant of circulating lipid levels, we investigated the role of both peripheral and central GLP-1 receptor (GLP-1R) agonism in regulation of VLDL production.

METHODS

The fructose-fed Syrian golden hamster was employed as a model of diet-induced insulin resistance and VLDL overproduction. Hamsters were treated with the GLP-1R agonist exendin-4 by intraperitoneal (ip) injection for peripheral studies or by intracerebroventricular (ICV) administration into the 3rd ventricle for central studies. Peripheral studies were repeated in vagotomised hamsters.

RESULTS

Short term (7-10 day) peripheral exendin-4 enhanced satiety and also prevented fructose-induced fasting dyslipidemia and hyperinsulinemia. These changes were accompanied by decreased fasting plasma glucose levels, reduced hepatic lipid content and decreased levels of VLDL-TG and -apoB100 in plasma. The observed changes in fasting dyslipidemia could be partially explained by reduced respiratory exchange ratio (RER) thereby indicating a switch in energy utilization from carbohydrate to lipid. Additionally, exendin-4 reduced mRNA markers associated with hepatic de novo lipogenesis and inflammation. Despite these observations, GLP-1R activity could not be detected in primary hamster hepatocytes, thus leading to the investigation of a potential brain-liver axis functioning to regulate lipid metabolism. Short term (4 day) central administration of exendin-4 decreased body weight and food consumption and further prevented fructose-induced hypertriglyceridemia. Additionally, the peripheral lipid-lowering effects of exendin-4 were negated in vagotomised hamsters implicating the involvement of parasympathetic signaling.

CONCLUSION

Exendin-4 prevents fructose-induced dyslipidemia and hepatic VLDL overproduction in insulin resistance through an indirect mechanism involving altered energy utilization, decreased hepatic lipid synthesis and also requires an intact parasympathetic signaling pathway.

Understanding the type 2 diabetes mellitus and cardiovascular disease risk paradox

Patients with diabetes have approximately a 2-fold increase in the risk for coronary heart disease, stroke, and death from vascular causes compared with patients who do not have diabetes. Interventions targeted at modifiable risk factors, such as smoking cessation and management of hypertension and dyslipidemia, reduce the risk of cardiovascular disease (CVD) in patients with type 2 diabetes mellitus (T2DM). Paradoxically, large randomized studies have failed to conclusively show that intensively lowering glucose reduces CVD event rates in patients with T2DM, despite pathophysiologic and epidemiologic evidence suggesting that hyperglycemia contributes to CVD. Although initiation of intensive glycemic control early in the disease course may be associated with a reduction in the long-term risk of cardiovascular (CV) events, this approach in those with long-standing or complicated T2DM is not of clear benefit and may even be harmful in some. Failure to mitigate risk with antihyperglycemic therapy and the potential for some treatments to increase CVD risk underlies a treatment paradox. New glucose-lowering therapies are now subject to close scrutiny for CV safety before and after drug approval. Results from the first trials designed to meet the recent CV regulatory requirements have shown no increased risk of major adverse CV events but also no CV benefit from dipeptidyl peptidase-4 inhibitor therapy, as well as a potentially increased risk of hospitalization for heart failure. Conclusive evidence of CV risk reduction with glucose-lowering therapy is still lacking and scrutiny of additional agents is necessary. Type 2 diabetes mellitus is a heterogeneous disease, for which patient-centered, individualized care, and goal-setting is appropriate. Interventions that focus on the management of CV risk factors and glucose lowering with medications that are not cardiotoxic represent an optimal and attainable treatment approach.

Effect of exenatide, sitagliptin, or glimepiride on β-cell secretory capacity in early type 2 diabetes

OBJECTIVE

Agents that augment GLP-1 effects enhance glucose-dependent β-cell insulin production and secretion and thus are hoped to prevent progressive impairment in insulin secretion characteristic of type 2 diabetes (T2D). The purpose of this study was to evaluate GLP-1 effects on β-cell secretory capacity, an in vivo measure of functional β-cell mass, early in the course of T2D.

RESEARCH DESIGN AND METHODS

We conducted a randomized controlled trial in 40 subjects with early T2D who received the GLP-1 analog exenatide (n = 14), the dipeptidyl peptidase IV inhibitor sitagliptin (n = 12), or the sulfonylurea glimepiride (n = 14) as an active comparator insulin secretagogue for 6 months. Acute insulin responses to arginine (AIRarg) were measured at baseline and after 6 months of treatment with 5 days of drug washout under fasting, 230 mg/dL (glucose potentiation of arginine-induced insulin release [AIRpot]), and 340 mg/dL (maximum arginine-induced insulin release [AIRmax]) hyperglycemic clamp conditions, in which AIRmax provides the β-cell secretory capacity.

RESULTS

The change in AIRpot was significantly greater with glimepiride versus exenatide treatment (P < 0.05), and a similar trend was notable for the change in AIRmax (P = 0.1). Within each group, the primary outcome measure, AIRmax, was unchanged after 6 months of treatment with exenatide or sitagliptin compared with baseline but was increased with glimepiride (P < 0.05). α-Cell glucagon secretion (AGRmin) was also increased with glimepiride treatment (P < 0.05), and the change in AGRmin trended higher with glimepiride than with exenatide (P = 0.06).

CONCLUSIONS

After 6 months of treatment, exenatide or sitagliptin had no significant effect on functional β-cell mass as measured by β-cell secretory capacity, whereas glimepiride appeared to enhance β- and α-cell secretion.

Diabetes and cardiovascular disease: focus on glucagon-like peptide-1 based therapies

Type 2 diabetes is a well known risk factor for cardiovascular disease (CVD). While glycemic control has consistently been shown to prevent microvascular complications, large randomized trials have not demonstrated the same consistent beneficial effects of intensive glycemic control in improving cardiovascular (CV) outcomes. Thus, optimal glucose control alone is not sufficient to reduce CV risk. Aggressive management of CV risk factors such as blood pressure, lipids, and body weight is also necessary. A growing body of evidence suggests that the recently available glucagon-like peptide 1 receptor (GLP-1R) agonists have beneficial CV effects beyond glucose control. Studies have demonstrated beneficial effects in the myocardium, endothelium, vasculature and various markers of cardiovascular risk such as body weight, blood pressure and dyslipidemia. Despite the growing evidence, large, randomized, blinded clinical trials with hard CV endpoints have not been performed. Most human studies have been small, and have focused on surrogate endpoints. The findings need to be confirmed by prospective, randomized cardiovascular outcomes trials. In this review we examine the GLP-1R agonist data on weight reduction, blood pressure lowering, beneficial changes in dyslipidemia, and improvements in myocardial and endothelial function. The safety as well as potential role of these agents in treatment regimens for type 2 diabetes is also addressed.

Weekly Exenatide Therapy

Background: Traditional diabetes therapies have been associated with weight gain, hypoglycemia, and/or high secondary failure rates. Glucagon-like peptide-1 (GLP-1) analog use is associated with a minimal risk of hypoglycemia, a persistent average weight loss of 2 to 3 kg, and sustained efficacy even after 3 years of use. Presently, 3 GLP-1 analogs are commercially available in the United States. Objective: To evaluate the real-world clinical utility of once weekly exenatide in type 2 diabetes mellitus (T2DM) patients who previously received once or twice daily GLP-1 therapy. Methods: In this pre–post observational study, electronic medical records (EMRs) were reviewed to identify patients meeting all study criteria. Data collected included baseline patient demographic information, duration of diabetes, disease states, medications, pertinent laboratory data, blood pressure, height, weight, and reported adverse drug events. Primary (changes in A1C and percentage of patients reporting adverse effects of therapy) and secondary (percentage of patients with A1C of <7% and changes in weight, blood pressure, and lipids) outcomes were evaluated using appropriate statistical analysis. Results: EMRs of 78 patients met all study criteria. Baseline patient demographic information included an average age of 61 ± 12 years, an average duration of T2DM of 14 ± 6 years, 59% of patients were male, and 93.6% were Caucasian. The baseline average body mass index was 39 ± 9.2, and mean A1C was 7.47 ± 1.45%. After a minimum of 3 months (average = 5.6 months) switchover, there were significant decreases in A1C (−0.35%; P = .0067) and weight (−1.6 kg; P = .0151). There were no significant changes in blood pressure or lipid levels. Two patients (2.5%) discontinued once weekly exenatide due to adverse reactions. Conclusion: Once weekly exenatide was generally well tolerated and significantly reduced A1C levels and body weight in patients with T2DM when switched from a shorter-acting GLP-1 analog.

Liraglutide as additional treatment to insulin in obese patients with type 1 diabetes mellitus

OBJECTIVE

Because approximately 40% of patients with type 1 diabetes have the metabolic syndrome, we tested the hypothesis that addition of liraglutide to insulin in obese patients with type 1 diabetes will result in an improvement in plasma glucose concentrations, a reduction in hemoglobin A1c (HbA1c), a fall in systolic blood pressure, and weight loss.

METHODS

This is a retrospective analysis of data obtained from 27 obese patients with type 1 diabetes treated with liraglutide in addition to insulin. Patients were also treated for hypertension. Paired t tests were used to compare the changes in HbA1c, insulin doses, body weight, body mass index, 4-week mean blood glucose concentrations (28-day insulin pump mean blood glucose), blood pressure, and lipid parameters prior to and 180 ± 14 days after liraglutide therapy.

RESULTS

Mean glucose concentrations fell from 191 ± 6 to 170 ± 6 mg/dL (P = .002). HbA1c fell from 7.89 ± 0.13% to 7.46 ± 0.13% (P = .001), without an increase in frequency of hypoglycemia. Mean body weight fell from 96.20 ± 3.68 kg to 91.56 ± 3.78 kg (P<.0001). Daily total and bolus doses of insulin fell from 73 ± 6 to 60 ± 4 (P = .008) units and from 40 ± 5 to 29 ± 3 units (P = .011), respectively. Mean systolic blood pressure fell from 130 ± 3 to 120 ± 4 mm Hg (P = .020).

CONCLUSION

Addition of liraglutide to insulin in obese patients with type 1 diabetes mellitus leads to improvements in glycemic control and HbA1c and to reductions in insulin dose, systolic blood pressure, and body weight.

Cardiovascular actions of incretin-based therapies

Glucagon-like peptide-1 receptor (GLP-1R) agonists and dipeptidyl peptidase-4 (DPP-4) inhibitors represent 2 distinct classes of incretin-based therapies used for the treatment of type 2 diabetes mellitus. Activation of GLP-1R signaling or inhibition of DPP-4 activity produces a broad range of overlapping and unique cardiovascular actions. Native GLP-1 regulates cardiovascular biology via activation of the classical GLP-1R, or through GLP-1(9-36), a cardioactive metabolite generated by DPP-4-mediated cleavage. In contrast, clinically approved GLP-1R agonists are not cleaved to GLP-1(9-36) and produce the majority of their actions through the classical GLP-1R. The cardiovascular mechanisms engaged by DPP-4 inhibition are more complex, encompassing increased levels of intact GLP-1, reduced levels of GLP-1(9-36), and changes in levels of numerous cardioactive peptides. Herein we review recent experimental and clinical advances that reveal how GLP-1R agonists and DPP-4 inhibitors affect the normal and diabetic heart and coronary vasculature, often independent of changes in blood glucose. Improved understanding of the complex science of incretin-based therapies is required to optimize the selection of these therapeutic agents for the treatment of diabetic patients with cardiovascular disease.

Addition of exenatide BID to insulin glargine: a post-hoc analysis of the effect on glycemia and weight across a range of insulin titration

BACKGROUND AND OBJECTIVE

In a 30 week, double-blind, randomized, controlled Phase 3 study in patients with type 2 diabetes mellitus, the addition of fixed-dose exenatide twice daily (BID) to titrated insulin glargine resulted in significant glycated hemoglobin (HbA(1c)) lowering and weight loss without increased hypoglycemia risk versus titrated insulin glargine alone. Because individualized insulin titration contributed to these results, this post-hoc analysis examined the results in the context of the degree of insulin titration that occurred.

METHODS

Subjects on pre-existing insulin glargine (with or without oral antidiabetes agents) were randomized to placebo (n = 123) or exenatide BID (n = 138; 5 µg for 4 weeks, then 10 µg ongoing). Insulin glargine was titrated in both arms per the Treat-to-Target algorithm. Tertiles (T1, T2, T3) were based on change in insulin dose from baseline to endpoint. Change in HbA(1c), hypoglycemia risk, and weight gain were assessed per insulin dose tertile.

RESULTS

The population comprised adult patients (mean age = 59 y) with type 2 diabetes and an HbA(1c) level between 7.0% and 10.5% (mean HbA(1c) = 8.4%). Insulin titration ranged from modest reductions in T1 to substantial increases in T3. Greater improvements in HbA1c were demonstrated with exenatide BID versus placebo in all tertiles (statistically significant in T2 and T3). With exenatide BID, more subjects achieved HbA(1c) <7.0% vs. placebo: T1, 44% vs. 29% (P = not significant); T2, 65% vs. 26%; T3, 54% vs. 29% (P < 0.05 for T2 and T3). Incidence of hypoglycemia was numerically lower with exenatide BID in all tertiles. Adjunctive exenatide BID was associated with statistically significantly greater weight loss (T1, T2) or mitigation of weight gain (T3) compared with placebo. Rates of nausea (42% vs. 8%), diarrhea (18% vs. 7%), and vomiting (18% vs. 4%) were higher with exenatide BID than with placebo and did not vary by tertile.

CONCLUSIONS

Addition of fixed-dose exenatide BID to optimized insulin glargine, regardless of the extent of insulin titration, significantly improved glycemia without increasing hypoglycemia risk, while mitigating insulin-induced weight gain in this post-hoc analysis.

Effects of exenatide in a morbidly obese patient with type 2 diabetes

INTRODUCTION

The effect of exenatide in weight loss has been reported. Presented here is a case of a morbidly obese patient with type 2 diabetes using exenatide who dramatically lost her body weight in a year and experienced improved glycemic control.

CASE REPORT

Exenatide therapy was initiated for a 59-year-old morbidly obese Japanese woman with type 2 diabetes. To examine the effects of the exenatide treatment, continuous glucose monitoring was performed, and blood was drawn at 0, 30, 60, 120, and 180 min after breakfast to measure insulin, glucagon, glucagon-like peptide-1 (GLP-1), and glucose-dependent insulinotropic peptide (GIP) levels. After 1 year of exenatide therapy, the patient lost 37.5 kg, her glycemic control improved, and her insulin sensitivity recovered. The patient's levels of insulin, glucagon, active GLP-1, and total GIP also decreased after 1 year of exenatide treatment.

CONCLUSION

The exenatide treatment was effective for reducing body weight and improving glycemic control. After 1 year of exenatide treatment, decreased glucagon, active GLP-1, and total GIP levels were observed following a meal, suggesting that exenatide might affect these hormonal reactions.

Long-term safety and efficacy of exenatide twice daily in Japanese patients with suboptimally controlled type 2 diabetes

Aims/Introduction:  We assessed the long-term (52 weeks) safety and efficacy of exenatide b.i.d. in Japanese patients with type 2 diabetes and suboptimal glycemic control.

MATERIALS AND METHODS

  Participants completing a 24-week randomized controlled trial of exenatide (5 μg, 10 μg or placebo b.i.d.) were invited to continue in a 28-week open-label extension study (5 μg, n = 64; 10 μg, n = 53). Safety measures included treatment-emergent adverse events (TEAE). Efficacy measures included change from baseline in glycosylated hemoglobin A1c (HbA1c) levels, proportion of participants achieving HbA1c target levels, fasting and seven-point, self-monitored blood glucose concentrations (SMBG), 1,5-anhydroglucitol concentrations, and bodyweight.

RESULTS

  A total of 60 and 49 participants in the exenatide 5 and 10 μg groups completed the study. The 52-week incidence of TEAE considered by investigators as related to the study drug was 80.6% (58/72) and 88.9% (64/72) in the exenatide 5 and 10 μg groups, respectively. Mild hypoglycemia and nausea were the most common TEAE. Most TEAE occurred during the first 24 weeks. Eight participants experienced serious adverse events. Exenatide treatment was associated with sustained decreases in HbA1c values, with 33.3-47.9% of participants achieving <6.9% HbA1c, sustained decreases in fasting plasma glucose concentrations and SMBG, and sustained increases in 1,5-anhydroglucitol concentrations. Exenatide 10 μg was associated with sustained weight loss.

CONCLUSIONS

  Long-term exenatide treatment had a similar safety profile to that observed previously and was efficacious in improving glycemic control in Japanese patients with suboptimally controlled type 2 diabetes. This trial was registered with ClinicalTrials.gov (no. NCT00577824). (J Diabetes Invest, doi: 10.1111/j.2040-1124.2011.00137.x, 2011).

Incretins and amylin: neuroendocrine communication between the gut, pancreas, and brain in control of food intake and blood glucose

Arguably the most fundamental physiological systems for all eukaryotic life are those governing energy balance. Without sufficient energy, an individual is unable to survive and reproduce. Thus, an ever-growing appreciation is that mammalian physiology developed a redundant set of neuroendocrine signals that regulate energy intake and expenditure, which maintains sufficient circulating energy, predominantly in the form of glucose, to ensure that energy needs are met throughout the body. This orchestrated control requires cross talk between the gastrointestinal tract, which senses the incoming meal; the pancreas, which produces glycemic counterregulatory hormones; and the brain, which controls autonomic and behavioral processes regulating energy balance. Therefore, this review highlights the physiological, pharmacological, and pathophysiological effects of the incretin hormones glucagon-like peptide-1 and gastric inhibitory polypeptide, as well as the pancreatic hormone amylin, on energy balance and glycemic control.

GLP-1R responsiveness predicts individual gastric bypass efficacy on glucose tolerance in rats

Several bariatric operations are currently used to treat obesity and obesity-related comorbidities. These vary in efficacy, but most are more effective than current pharmaceutical treatments. Roux-en-Y gastric bypass (RYGB) produces substantial body weight (BW) loss and enhanced glucose tolerance, and is associated with increased secretion of the gut hormone glucagon-like peptide 1 (GLP-1). Given the success of GLP-1-based agents in lowering blood glucose levels and BW, we hypothesized that an individual sensitivity to GLP-1 receptor agonism could predict metabolic benefits of surgeries associated with increased GLP-1 secretion. One hundred ninety-seven high-fat diet-induced obese male Long-Evans rats were monitored for BW loss during exendin-4 (Ex4) administration. Stable populations of responders and nonresponders were identified based on Ex4-induced BW loss and GLP-1-induced improvements in glucose tolerance. Subpopulations of Ex4 extreme responders and nonresponders underwent RYGB surgery. After RYGB, responders and nonresponders showed similar BW loss compared with sham, but nonresponders retained impaired glucose tolerance. These data indicate that the GLP-1 response tests may predict some but not all of the improvements observed after RYGB. These findings present an opportunity to optimize the use of bariatric surgery based on an improved understanding of GLP-1 biology and suggest an opportunity for a more personalized therapeutic approach to the metabolic syndrome.

Exendin-4 effects on islet volume and number in mouse pancreas

The aim of this study was to evaluate Exendin-4 (EX-4) effects on islet volume and number in the mouse pancreas. Thirty-two healthy adult male NMRI mice were randomly divided into control and experimental groups. EX-4 was injected intraperitoneally (i. p.) at doses of 0.25 (E1 group), 0.5 (E2 group), and 1 µg/kg (E3 group), twice a day for 7 consecutive days. One day after the final injection, the mice were sacrificed, and the pancreas from each animal dissected out, weighed, and fixed in 10% formalin for measurement of pancreas and islet volume, and determination of islet number by stereological assessments. There was a significant increase in the weight of pancreases in the E3 group. Islet and pancreas volumes in E1 and E2 groups were unchanged compared to the control group. The E3 group showed a significant increase in islet and pancreas volume (P < 0.05). There were no significant changes in the total number of islets in all three experimental groups. The results revealed that EX-4 increased pancreas and islet volume in non-diabetic mice. The increased total islet mass is probably caused by islet hypertrophy without the formation of additional islets.

Co-agonist of glucagon and GLP-1 reduces cholesterol and improves insulin sensitivity independent of its effect on appetite and body weight in diet-induced obese C57 mice

Dual agonism of glucagon and glucagon-like peptide-1 (GLP-1) receptors reduce body weight without inducing hyperglycemia in rodents. However, the effect of a co-agonist on insulin sensitivity and lipid metabolism has not been thoroughly assessed. Diet-induced obese (DIO) mice received 0.5 mg·kg(-1) of co-agonist or 2.5 mg·kg(-1) of glucagon or 8 μg·kg(-1) of exendin-4 by subcutaneous route, twice daily, for 28 days. A separate group of mice was pair-fed to the co-agonist-treated group for 28 days. Co-agonist treatment reduced food intake and reduced body weight up to 28 days. In addition, it reduced leptin levels and increased fibroblast growth factor 21 (FGF21) levels in plasma, when compared with control and pair-fed groups. Co-agonist treatment decreased triglyceride levels in serum and liver and reduced serum cholesterol, mainly due to reduction in low-density lipoprotein (LDL) cholesterol. These changes were not seen with pair-fed controls. Co-agonist treatment improved glucose tolerance and increased insulin sensitivity, as observed during glucose and insulin-tolerance test, hyperinsulinemic clamp, and reduced gluconeogenesis, as observed in pyruvate-tolerance test. The effects on insulin sensitivity and lipid levels are mostly independent of the food intake or body weight lowering effect of the co-agonist.

Use of exenatide and liraglutide in Denmark: a drug utilization study

PURPOSE

The purpose of this study was to characterise the utilization of the glucagon-like peptide-1 (GLP-1) analogues exenatide and liraglutide in Denmark.

METHODS

From the Danish National Prescription Registry, we extracted all prescriptions for either liraglutide or exenatide twice-daily in the period 1 April 2007 to 31 December 2012. Using descriptive statistics, we calculated incidence rates, prevalence proportions, daily consumption, and concomitant drug use. For a subset of users we included data from other registries and characterised the baseline characteristics of incident users of GLP-1 analogues.

RESULTS

We identified 21,561 and 2,354 users of liraglutide and exenatide respectively. From market entry in 2009 liraglutide showed an increasing prevalence reaching 2.4 per thousand inhabitants in 2012. Exenatide ranged between 0.01 and 0.25 per thousand inhabitants from 2007 to 2012. Treatment intensity showed geographical variation ranging from 1.84per thousand inhabitants to 3.22 per thousand inhabitants for liraglutide. Average doses were 1.34 mg/day (liraglutide) and 16.4 μg/day (exenatide). Treatment initiation was most often performed by a hospital physician and was not associated with any changes in concomitant treatment with antihypertensives, cholesterol-lowering drugs or anticoagulants. Of liraglutide and exenatide users, 38 % and 43 % also used insulin. Low kidney function (eGFR < 30 ml/min) was found in 10.1 % and 9.0 % of users of liraglutide and exenatide respectively.

CONCLUSIONS

The preferred GLP-1 analogue in Denmark is liraglutide. Certain aspects of the utilization of GLP-1 analogues, such as large regional differences and concomitant use of GLP-1 analogues and insulin, warrant further investigation.

Hindbrain GLP-1 receptor-mediated suppression of food intake requires a PI3K-dependent decrease in phosphorylation of membrane-bound Akt

Glucagon-like peptide-1 (GLP-1) receptors (GLP-1R) expressed in the nucleus tractus solitarius (NTS) are physiologically required for the control of feeding. Recently, NTS GLP-1R-mediated suppression of feeding was shown to occur via a rapid PKA-induced suppression of AMPK and activation of MAPK signaling. Unknown are the additional intracellular signaling pathways that account for the long-term hypophagic effects of GLP-1R activation. Because cAMP/PKA activity can promote PI3K/PIP3-dependent translocation of Akt to the plasma membrane, we hypothesize that hindbrain GLP-1R-mediated control of feeding involves a PI3K-Akt-dependent pathway. Importantly, the novel evidence presented here challenges the dogmatic view that PI3K phosphorylation results in an obligatory activation of Akt and instead supports a growing body of literature showing that activation of cAMP/PKA can inhibit Akt phosphorylation at the plasma membrane. Behavioral data show that inhibition of hindbrain PI3K activity by a fourth icv administration of LY-294002 (3.07 μg) attenuated the food intake- and body weight-suppressive effects of a fourth icv administration of the GLP-1R agonist exendin-4 (0.3 μg) in rats. Hindbrain administration of triciribine (10 μg), an inhibitor of PIP3-dependent translocation of Akt to the cell membrane, also attenuated the intake-suppressive effects of a fourth icv injection of exendin-4. Immunoblot analyses of ex vivo NTS tissue lysates and in vitro GLP-1R-expressing neurons (GT1-7) support the behavioral findings and show that GLP-1R activation decreases phosphorylation of Akt in a time-dependent fashion. Current data reveal the requirement of PI3K activation, PIP3-dependent translocation of Akt to the plasma membrane, and suppression in phosphorylation of membrane-bound Akt to mediate the food intake-suppressive effects of hindbrain GLP-1R activation.

GLP-1R agonism enhances adjustable gastric banding in diet-induced obese rats

Bariatric procedures vary in efficacy, but overall are more effective than behavioral and pharmaceutical treatment. Roux-en-Y gastric bypass causes increased secretion of glucagon-like peptide 1 (GLP-1) and reduces body weight (BW) more than adjustable gastric banding (AGB), which does not trigger increased GLP-1 secretion. Since GLP-1-based drugs consistently reduce BW, we hypothesized that GLP-1 receptor (GLP-1R) agonists would augment the effects of AGB. Male Long-Evans rats with diet-induced obesity received AGB implantation or sham surgery. GLP-1R agonism, cannabinoid receptor-1 (CB1-R) antagonism, or vehicle was combined with inflation to evaluate interaction between AGB and pharmacological treatments. GLP1-R agonism reduced BW in both sham and AGB rats (left uninflated) compared with vehicle-treated animals. Subsequent band inflation was ineffective in vehicle-treated rats but enhanced weight loss stimulated by GLP1-R agonism. In contrast, there was no additional BW loss when CB1-R antagonism was given with AGB. We found band inflation to trigger neural activation in areas of the nucleus of the solitary tract known to be targeted by GLP-1R agonism, offering a potential mechanism for the interaction. These data show that GLP-1R agonism, but not CB1-R antagonism, improves weight loss achieved by AGB and suggest an opportunity to optimize bariatric surgery with adjunctive pharmacotherapy.

Blood pressure-lowering effects of GLP-1 receptor agonists exenatide and liraglutide: a meta-analysis of clinical trials

AIMS

Aside from lowering blood glucose, glucagon-like peptide-1 receptor agonists (GLP-1 RAs) attract much attention because of their cardioprotective effects. The aim of this study was to assess the blood pressure-lowering effects of the GLP-1 RAs exenatide and liraglutide compared with other common drugs used to treat type 2 diabetes (T2DM) based on randomized controlled trials (RCTs) including data describing complete blood pressure (BP) changes from baseline.

METHODS

We searched the major databases for published or unpublished RCTs that had been performed in patients with T2DM and compared the effects of exenatide and liraglutide to those of other common drugs used to treat T2DM. The RCTs that included data describing BP changes between the baseline and the end of the study were selected for further analysis.

RESULTS

A total of 16 RCTs that enrolled 3443 patients in the GLP-1 RA treatment group and 2417 subjects in the control group were included in this meta-analysis. The GLP-1 RA exenatide reduced systolic blood pressure (SBP) when compared with both placebo and insulin glargine, with mean differences of -5.24 and -3.46 mmHg, respectively, and with 95% confidence intervals (CI) of -6.88 to -3.59, p < 0.00001 and -3.63 to -3.29, p < 0.00001, respectively. Meanwhile, in the exenatide-treated group, diastolic blood pressure (DBP) was reduced by -5.91 mmHg, with a 95% CI of -7.53 to -4.28, p < 0.00001 compared with the placebo group, and -0.99 mmHg with a 95% CI of -1.12 to -0.87, p < 0.00001 compared with the sitagliptin group. SBP changes in this meta-analysis were assessed in the groups treated with 1.2 or 1.8 mg liraglutide per day. In the 1.2 mg-treated group, liraglutide treatment reduced SBP compared with placebo and glimepiride treatment, with mean differences of -5.60 and -2.38 mmHg, and 95% CIs of -5.84 to -5.36, p < 0.00001 and -4.75 to -0.01, p = 0.05, respectively. In the 1.8-mg-treated group, liraglutide also reduced SBP compared with placebo and glimepiride treatment with mean differences of -4.49 and -2.62 mmHg, and a 95% CI of -4.73 to -4.26, p < 0.00001, and -2.91 to -2.33, p < 0.00001, respectively.

CONCLUSION

Treatment with the GLP-1 RAs exenatide and liraglutide reduced SBP and DBP by 1 to 5 mmHg compared with some other anti-diabetic drugs including insulin, glimepiride and placebo for patients with T2DM. GLP-1 RAs may offer an alternative therapy for these patients and will help provide extra cardiovascular benefits.

Extra-pancreatic effects of incretin-based therapies: potential benefit for cardiovascular-risk management in type 2 diabetes

Development of cardiovascular disease is one of the major complications of type 2 diabetes mellitus (T2DM). The chronic hyperglycaemic state is often accompanied by dyslipidaemia, hypertension, low-grade systemic inflammation and oxidative stress which collectively result in a high risk of micro- and macrovascular complications. Current glucose-lowering agents do not sufficiently address fore-mentioned macrovascular-risk factors. Recently, new therapeutic agents were introduced, based on the incretin hormone glucagon-like peptide-1 (GLP-1), that is, the GLP-1 receptor agonists (GLP-1RA) and dipeptidyl-peptidase 4 (DPP-4) inhibitors. Beside its effect on pancreatic insulin secretion, GLP-1 exerts several extra-pancreatic effects such as slowing down gastric emptying, promoting satiety and reducing food intake and weight loss. Also, GLP-1 and GLP-1RA were shown to improve cardiovascular-risk profiles, by reducing body fat content, blood pressure, circulating lipids and inflammatory markers in patients with T2DM. This review summarizes the presently known evidence with regard to extra-pancreatic effects of the incretin-based agents, focusing on the actions that improve the cardiovascular-risk profile. We present available data from clinical trials of at least 24 week duration, but also findings from small-sized clinical 'proof of principle' studies. We conclude that GLP-1 RA and to a lesser extent DPP-4 inhibitors are promising agents with regard to their effects on body weight, blood pressure and lipids, which collectively ameliorate the cardiovascular-risk profile and as such may have added value in the treatment of T2DM. However, large-sized long-term outcome studies are warranted to show the true added value of these agents in the treatment of patients with T2DM.

Current issues in GLP-1 receptor agonist therapy for type 2 diabetes

The clinical management of hyperglycemia in patients with type 2 diabetes mellitus (T2DM) is guided not only by published treatment algorithms, but also by consideration of recent evidence and through consultation with colleagues and experts. Recent studies have dramatically increased the amount of information regarding the use of glucagon-like peptide-1 receptor agonists (GLP-1 RAs). Topics that may be of particular interest to clinicians who treat T2DM patients include relative glycemic control efficacy of GLP-1 RAs, use of GLP-1 RAs across T2DM progression and in combination with insulin, recent data regarding GLP-1 RA safety, nonglycemic actions of GLP-1 RAs, including weight effects, and impact of GLP-1 RAs on patient quality of life and treatment satisfaction. The following review includes expert consideration of these topics with emphasis on recent, relevant reports to illustrate current perspectives.

PAS kinase as a nutrient sensor in neuroblastoma and hypothalamic cells required for the normal expression and activity of other cellular nutrient and energy sensors

PAS kinase (PASK) is a nutrient sensor that is highly conserved throughout evolution. PASK-deficient mice reveal a metabolic phenotype similar to that described in S6 kinase-1 S6K1-deficient mice that are protected against obesity. Hypothalamic metabolic sensors, such as AMP-activated protein kinase (AMPK) and the mammalian target of rapamycin (mTOR), play an important role in feeding behavior, the homeostasis of body weight, and energy balance. These sensors respond to changes in nutrient levels in the hypothalamic areas involved in feeding behavior and in neuroblastoma N2A cells, and we have recently reported that those effects are modulated by the anorexigenic peptide glucagon-like peptide-1 (GLP-1). Here, we identified PASK in both N2A cells and rat VMH and LH areas and found that its expression is regulated by glucose and GLP-1. High levels of glucose decreased Pask gene expression. Furthermore, PASK-silenced N2A cells record an impaired response by the AMPK and mTOR/S6K1 pathways to changes in glucose levels. Likewise, GLP-1 effect on the activity of AMPK, S6K1, and other intermediaries of both pathways and the regulatory role at the level of gene expression were also blocked in PASK-silenced cells. The absence of response to low glucose concentrations in PASK-silenced cells correlates with increased ATP content, low expression of mRNA coding for AMPK upstream kinase LKB1, and enhanced activation of S6K1. Our findings indicate that, at least in N2A cells, PASK is a key kinase in GLP-1 actions and exerts a coordinated response with the other metabolic sensors, suggesting that PASK might play an important role in feeding behavior.

Circulating glucagon-like peptide-1 increases in response to short-term overfeeding in men

BACKGROUND

Glucagon-like Peptide-1 (GLP-1) is an incretin hormone secreted from the gastrointestinal tract that facilitates the glucose-dependent insulin response. Additionally, GLP-1 is thought to be involved in energy homeostasis. Currently little is known about GLP-1's responsiveness to an energy surplus, a fundamental cause of obesity and diabetes. Our objective was to examine the response of serum GLP-1 to short-term (7 day) overfeeding in young men.

METHODS

Seventy-two young men from the Canadian province of Newfoundland were recruited for the study. For 7-days, the subjects consumed 70% more calories than required at baseline.Various measurements including: anthropometrics, body composition, markers of glucose/lipid metabolism and serum total GLP-1, were taken at a fasted state before (day 1) and after (day 8) the challenge. Paired t-test analyses were used to assess the change in variables after the overfeeding period. Additionally, the relationship between serum GLP-1 and the measured variables at baseline and change due to overfeeding were analyzed.

RESULTS

Serum GLP-1 was significantly increased in all groups in response to the 7-day energy surplus, indicating the increase was independent of adiposity status. There was no significant difference in fasting GLP-1 at baseline between the normal weight and overweight/obese groups. At baseline, GLP-1 concentration negatively correlated with HDL-cholesterol and positively correlated with triacylglycerols and markers of insulin resistance in the overweight/obese group. Also GLP-1 was negatively correlated with change in percent gynoid fat in the overweight/obese subjects. Percent change in GLP-1 was negatively associated with percent change in gynoid fat in the normal weight group and positively associated with percent change in cholesterol in the overweight/obese group. Percentage change of circulating triacylglycerols was positively associated with percent change in GLP-1 in both adiposity groups.

CONCLUSION

Our findings showed that GLP-1 serum concentration is not a significant factor in determining obesity status. The increase of GLP-1 in all subjects regardless of obesity status, suggest GLP-1 serves as a protective role, counteracting energy surplus.

Evaluating Second-Line Treatment Options for Type 2 Diabetes: Focus on Secondary Effects of GLP-1 Agonists and DPP-4 Inhibitors

OBJECTIVE

To discuss the controversy surrounding selection of second-line type 2 diabetes mellitus (T2DM) therapy by reviewing available data regarding secondary effects of glucagon-like peptide-1 receptor (GLP-1) agonists and dipeptidyl peptidase-4 (DPP-4) inhibitors, which include low hypoglycemia risk, weight loss, and cardiovascular (CV) and β-cell function benefits.

DATA SOURCES

A MEDLINE search (1966–March 2013) was conducted using the following key terms: β-cell protection, blood pressure, DPP-4 inhibitors, exena tide, exenatide extended-release, GLP-1 agonists, hypoglycemia, lina glip tin, lipid, liraglutide, pancreatitis, saxagliptin, sitagliptin, and type 2 diabetes.

STUDY SELECTION AND DATA EXTRACTION

Identified articles published in English were evaluated for inclusion, with priority given to randomized controlled trials in humans receiving incretin monotherapy or incretin combination therapy with metformin. References identified in these articles were reviewed for additional trials.

DATA SYNTHESIS

Most patients with T2DM use combination therapy; however, determination of the second-line agent that is most appropriate is debatable. Prior to the use of incretin therapies, traditional second-line agents included sulfonylureas, thiazolidinediones, and basal insulin, all of which demonstrate undesirable adverse effects. In addition to improving glycemic control, incretin therapies have demonstrated benefits concerning hypoglycemic risk and weight loss in addition to potential improvements in CV risk factors and β-cell function. While there are risks associated with using incretins, most patients with T2DM are good candidates for incretins and could benefit from their potential secondary effects. Cost remains a barrier to initiating these agents.

CONCLUSIONS

Demonstrated secondary benefits in addition to efficacy may make GLP-1 agonists and DPP-4 inhibitors a more favorable option than other second-line T2DM therapies.

Exenatide once weekly improved glycaemic control, cardiometabolic risk factors and a composite index of an HbA1c < 7%, without weight gain or hypoglycaemia, over 52 weeks

AIMS

Type 2 diabetes mellitus (T2DM) is often associated with cardiovascular (CV) risk factors such as obesity, hypertension and dyslipidemia. The objective of this analysis was to evaluate potential effects of exenatide once weekly (ExQW), a GLP-1 receptor agonist, on glycaemic control and CV risk factors.

METHODS

This analysis included 675 Intent-to-Treat patients with T2DM [baseline (mean ± SD) HbA1c, 8.1 ± 1.2%; fasting blood glucose (FBG), 166 ± 48 mg/dl; weight, 94.3 ± 19.4 kg; systolic/diastolic blood pressure (SBP/DBP), 129 ± 15/78 ± 9 mm Hg; total cholesterol, 178.5 ± 41.9 mg/dl; low-density lipoprotein (LDL), 100.1 ± 35.0 mg/dl; high-density lipoprotein (HDL), 44.5 ± 11.6 mg/dl; triglycerides, 155.6 ± 3.3 mg/dl; alanine aminotransferase (ALT), 32.1 ± 19.5 U/l] treated with diet and exercise alone or in combination with metformin, sulfonylurea, and/or thiazolidinedione who received 52 weeks of ExQW in four clinical trials.

RESULTS

At 52 weeks, ExQW significantly improved HbA1c [mean (SE) change from baseline, -1.3 (0.05)%], FBG [-36.3 (2.02) mg/dl], body weight [-2.6 (0.19) kg], SBP/DBP [-3.6 (0.56) mm Hg/-1.2 (0.34) mm Hg], total cholesterol, -4.4 (1.33) mg/dl; LDL, -2.6 (1.08) mg/dl; HDL, 1.1 (0.31) mg/dl; triglycerides, -7 (1.6)%], and ALT [-4.3 (0.71) IU/l] concentrations, with greater improvements in patients with elevated analyte levels at baseline. Improvements were observed across a range of background antihyperglycaemia therapies. Of patients completing 52 weeks, 19% achieved the composite American Diabetes Association goal (HbA1c < 7.0%, BP < 130/80 mm Hg, LDL < 100 mg/dl), compared to 1% at baseline. Nearly half (48%) achieved HbA1c < 7.0% without weight gain or major/minor hypoglycaemia. Nausea was the most frequent adverse event and was predominantly mild. Hypoglycaemia was infrequent, and more common with a sulfonylurea.

CONCLUSIONS

With 52 weeks of ExQW, patients experienced sustained improvements in glycaemic control and CV risk factors, with an increased likelihood of achieving both a clinically relevant composite outcome (HbA1c < 7% without weight gain or increased risk of hypoglycaemia) and a composite of key therapeutic goals (HbA1c < 7%, BP < 130/80 mm Hg, LDL < 100 mg/dl).

Evolution of exenatide as a diabetes therapeutic

Type 2 diabetes (T2DM) is a disease of epidemic proportion associated with significant morbidity and excess mortality. Optimal glucose control reduces the risk of microvascular and possibly macrovascular complications due to diabetes. However, glycemic control is rarely optimal and several therapeutic interventions for the treatment of diabetes cause hypoglycemia and weight gain; some may exacerbate cardiovascular risk. Exenatide (synthetic exendin-4) is a glucagon- like peptide-1 receptor (GLP-1R) agonist developed as a first-in-class diabetes therapy. This review presents an overview of the evolution of exenatide as a T2DM treatment, beginning with the seminal preclinical discoveries and continuing through to clinical pharmacology investigations and phase 3 clinical trials. In patients with T2DM, exenatide enhanced glucose-dependent insulin secretion, suppressed inappropriately elevated glucagon secretion, slowed gastric emptying, and enhanced satiety. In controlled phase 3 clinical trials ranging from 12 to 52 weeks, 10-mcg exenatide twice daily (ExBID) reduced mean HbA1c by -0.8% to -1.7% as monotherapy or in combination with metformin (MET), sulfonylureas (SFU), and/or thiazolidinediones (TZD); with mean weight losses of -1.2 kg to -8.0 kg. In controlled phase 3 trials ranging from 24 to 30 weeks, a 2-mg once-weekly exenatide formulation (ExQW) reduced mean HbA1c by -1.3% to -1.9%, with mean weight reductions of -2.3 to -3.7 kg. Exenatide was generally well-tolerated. The most common side effects were gastrointestinal in nature, mild, and transient. Nausea was the most prevalent adverse event. The incidence of hypoglycemia was generally low. By building upon early observations exenatide was successfully developed into an effective diabetes therapy.

Neonatal exendin-4 reduces growth, fat deposition and glucose tolerance during treatment in the intrauterine growth-restricted lamb

Background

IUGR increases the risk of type 2 diabetes mellitus (T2DM) in later life, due to reduced insulin sensitivity and impaired adaptation of insulin secretion. In IUGR rats, development of T2DM can be prevented by neonatal administration of the GLP-1 analogue exendin-4. We therefore investigated effects of neonatal exendin-4 administration on insulin action and β-cell mass and function in the IUGR neonate in the sheep, a species with a more developed pancreas at birth.

Methods

Twin IUGR lambs were injected s.c. daily with vehicle (IUGR+Veh, n = 8) or exendin-4 (1 nmol.kg^-1, IUGR+Ex-4, n = 8), and singleton control lambs were injected with vehicle (CON, n = 7), from d 1 to 16 of age. Glucose-stimulated insulin secretion and insulin sensitivity were measured in vivo during treatment (d 12–14). Body composition, β-cell mass and in vitro insulin secretion of isolated pancreatic islets were measured at d 16.

Principal Findings

IUGR+Veh did not alter in vivo insulin secretion or insulin sensitivity or β-cell mass, but increased glucose-stimulated insulin secretion in vitro. Exendin-4 treatment of the IUGR lamb impaired glucose tolerance in vivo, reflecting reduced insulin sensitivity, and normalised glucose-stimulated insulin secretion in vitro. Exendin-4 also reduced neonatal growth and visceral fat accumulation in IUGR lambs, known risk factors for later T2DM.

Conclusions

Neonatal exendin-4 induces changes in IUGR lambs that might improve later insulin action. Whether these effects of exendin-4 lead to improved insulin action in adult life after IUGR in the sheep, as in the PR rat, requires further investigation.

Palatable food avoidance and acceptance learning with different stressors in female rats

Stress activates the hypothalamus-pituitary-adrenal (HPA) axis leading to the release of glucocorticoids (GC). Increased activity of the HPA axis and GC exposure has been suggested to facilitate the development of obesity and metabolic syndrome. Nonetheless, different stressors can produce distinct effects on food intake and may support different directions of food learning e.g. avoidance or acceptance. This study examined whether interoceptive (LiCl and exendin-4) and restraint stress (RS) support similar or distinct food learning. Female rats were exposed to different stressors after their consumption of a palatable food (butter icing). After four palatable food-stress pairings, distinct intakes of the butter icing were observed in rats treated with different stressors. Rats that received butter icing followed by intraperitoneal injections of LiCl (42.3mg/kg) and exendin-4 (10μg/kg) completely avoided the palatable food with subsequent presentations. In contrast, rats experiencing RS paired with the palatable food increased their consumption of butter icing across trials and did so to a greater degree than rats receiving saline injections. These data indicate that interoceptive and psychosocial stressors support conditioned food avoidance and acceptance, respectively. Examination of c-Fos immunoreactivity revealed distinct neural activation by interoceptive and psychosocial stressors that could provide the neural basis underlying opposite direction of food acceptance learning.

Evaluating the cost-effectiveness of laparoscopic adjustable gastric banding versus standard medical management in obese patients with type 2 diabetes in the UK

AIM

To evaluate the cost-effectiveness of laparoscopic adjustable gastric banding (LAGB) versus standard medical management (SMM) in obese patients with type 2 diabetes from a UK healthcare payer perspective.

METHODS

A validated computer model of diabetes was used to project outcomes reported from a randomized clinical trial of LAGB versus SMM in obese patients with type 2 diabetes. Two-year follow-up data from the trial were projected over a 40-year time horizon and cost-effectiveness was assessed from the perspective of the National Health Service. Future costs and clinical outcomes were discounted at 3.5% annually and all costs were reported in 2010 pounds sterling. A series of sensitivity analyses were performed.

RESULTS

LAGB was associated with benefits in HbA1c, systolic blood pressure, body mass index and serum lipid concentrations, which led to significant increases in discounted life expectancy (an increase of 0.64 years) and quality-adjusted life expectancy (an increase of 0.92 quality-adjusted life years, QALYs) and reduced incidence of diabetes complications relative to SMM. Treatment costs in the LAGB arm increased by 4552 Great British Pounds (GBP), but this was partially offset by cost savings resulting from a reduction in the incidence of all modelled diabetes complications. The incremental cost-effectiveness ratio of GBP 3602 per QALY in the base case fell well below commonly quoted willingness-to-pay thresholds in the UK setting.

CONCLUSIONS

On the basis of data from a recent randomized controlled trial, LAGB is likely to be considered cost-effective from the healthcare payer perspective when compared with SMM of obesity in patients with type 2 diabetes in the UK setting.

Induction of apolipoprotein A-I gene expression by glucagon-like peptide-1 and exendin-4 in hepatocytes but not intestinal cells

OBJECTIVE

Diabetic dyslipidemia is an important risk factor for the development of macrovascular complications. Recent clinical trials suggest that diabetics treated with glucagon-like peptide-1 (GLP-1) have normalized lipid levels, including an increase in plasma high-density lipoprotein cholesterol (HDLc) levels.

METHODS

To determine if GLP-1 (7-36 amide) and the GLP-1-like insulinotropic peptide exendin-4 regulate expression of apolipoprotein A-I (apo A-I), the primary anti-atherogenic component of high-density lipoprotein (HDL), HepG2 hepatocytes and Caco-2 intestinal cells, representative of tissues that express the majority of apo A-I, were treated with increasing amounts of each peptide and apo A-I gene expression was measured in the conditioned medium.

RESULTS

Apo A-I secretion increased in both GLP-1 and exendin-4-treated HepG2, but not Caco-2 cells, and this was accompanied by similar changes in apo A-I mRNA levels and apo A-I promoter activity. Induction of apo A-I promoter activity by GLP-1 and exendin-4 required an SP1-responsive element. Hepatic ATP binding cassette protein A1 (ABCA1) expression, but not scavenger receptor class B type1 receptor expression was also induced by GLP-1 and exendin-4.

CONCLUSIONS

These results suggest that GLP-1- and exendin-4-mediated changes in HDLc are likely due to changes in hepatic expression of apo A-I and ABCA1.

Effects of taspoglutide on glycemic control and body weight in obese patients with type 2 diabetes (T-emerge 7 study)

OBJECTIVE

Therapies that lower blood glucose and provide weight loss may provide meaningful benefits for obese patients with type 2 diabetes mellitus (T2DM). This study assessed the efficacy of taspoglutide compared with placebo on glycemic control and weight in obese patients with T2DM inadequately controlled with metformin monotherapy.

DESIGN AND METHODS

In a 24-week, randomized, double-blind, placebo-controlled, multicenter trial, obese adults with T2DM were randomized (1:1) to weekly subcutaneous taspoglutide 20 mg (10 mg for first 4 weeks) (n = 154) or placebo (n = 151) for 24 weeks. Efficacy measures included hemoglobin A1c (HbA1c) levels, body weight, percentage of patients achieving HbA1c ≤6.5 and ≤7.0%, and fasting plasma glucose (FPG). Adverse events (AEs) were assessed.

RESULTS

Mean baseline HbA1c was 7.55% and mean baseline BMI was 36.7 kg/m(2) . HbA1c reductions from baseline were significantly greater with taspoglutide than placebo (least square mean [LSMean], -0.81% vs. -0.09%; P < 0.0001). Weight loss at week 24 was significantly greater with taspoglutide than placebo (LSMean, -3.16 vs. -1.85 kg; P < 0.01). In the taspoglutide and placebo groups, target HbA1c levels (≤6.5%) were achieved by 49 and 16% of patients, respectively, while 72 and 36% achieved HbA1c levels ≤7%. Decreases in FPG were significantly greater with taspoglutide than placebo (-23.59 vs. 0.09 mg/dl; P < 0.0001). Nausea and vomiting were the most common AEs associated with taspoglutide, but tended to be transient and generally mild or moderate.

CONCLUSIONS

In obese patients with T2DM, once-weekly taspoglutide provided the combined benefits of glycemic control and weight loss.

Investigation of the haemodynamic effects of exenatide in healthy male subjects

AIMS

In clinical studies of glucagon-like peptide-1 (GLP-1) agonists used in the management of patients with type 2 diabetes, there is often a small accompanying fall in blood pressure. The mechanism underlying this effect is not known, although exenatide, a GLP-1 mimetic, has acute regional vasodilator properties in rats. We have therefore studied the haemodynamic effects of exenatide in healthy male volunteers.

METHODS

We compared the effects of a single 10 µg subcutaneous injection of exenatide with placebo in a double-blind, randomized, crossover study. For 2 h after dosing, haemodynamic measurements were made using a Finometer, venous occlusion plethysmography and Doppler ultrasound. The urine sodium : creatinine excretion ratio was determined.

RESULTS

At the end of the study when exenatide was compared with placebo, heart rate had risen by a mean of 8.2 (95% CI 4.2, 12.2, P < 0.01) beats min(-1) , cardiac output by a mean of 1.2 (95% CI 0.42, 20.3, P < 0.05) l min(-1) and total peripheral resistance had fallen by 120 (95% CI -8, -233, P < 0.05) dyn s cm(-5) .There were no differences in blood pressure. The urinary sodium : creatinine ratio was increased by mean 12.4 (95% CI 4.6, 20.2, P < 0.05) mmol mmol(-1) when exenatide was compared with placebo.

CONCLUSIONS

Exenatide has significant haemodynamic effects in healthy volunteers. The results of this study are consistent with exenatide having both vasodilator and natriuretic properties. The vascular changes may contribute to the hypotensive effect of exenatide when used chronically in patients with diabetes.

Glycemic variability in type 2 diabetes mellitus: oxidative stress and macrovascular complications

Diabetes mellitus is a world-wide health issue with potential for significant negative health outcomes, including microvascular and macrovascular complications. The relationship of hemoglobin HbA1c and other glycosylation end products (AGEs) to these complications, particularly microvascular disease, is well understood. More recent evidence suggests that glycemic variability may be associated with diabetes macrovascular complications. As HbA1c is better representative of average glucose levels and does not account as well for glycemic variability, hence new methods to assess and treat this variability is needed to reduce incidence of complications. In this chapter, the relationship of glycemic control to diabetes complications will be explored with focus on the mechanisms of tissue damage from this variability along with the oxidative stress. Additionally, treatment strategies to optimize HbA1c and glycemic variability with the goal of reducing risk of complications in persons with diabetes are reviewed.