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

Exenatide versus insulin glargine in patients with type 2 diabetes in the UK: a model of long-term clinical and cost outcomes

OBJECTIVES

The aim of this study was to evaluate the long-term clinical and economic outcomes associated with exenatide or insulin glargine, added to oral therapy in individuals with type 2 diabetes inadequately controlled with combination oral agents in the UK setting.

METHODS

A published and validated computer simulation model of diabetes was used to project long-term complications, life expectancy, quality-adjusted life expectancy and direct medical costs. Probabilities of diabetes-related complications were derived from published sources. Treatment effects and patient characteristics were extracted from a recent randomised controlled trial comparing exenatide with insulin glargine. Simulations incorporated published quality of life utilities and UK-specific costs from 2004. Pharmacy costs for exenatide were based on 20, 40, 60, 80 and 100% of the US value (as no price for the UK was available at the time of analysis). Future costs and clinical benefits were discounted at 3.5% annually. Sensitivity analyses were performed.

RESULTS

In the base-case analysis exenatide was associated with improvements in life expectancy of 0.057 years and in quality-adjusted life expectancy of 0.442 quality-adjusted life years (QALYs) versus insulin glargine. Long-term projections demonstrated that exenatide was associated with a lower cumulative incidence of most cardiovascular disease (CVD) complications and CVD-related death than insulin glargine. Using the range of cost values, evaluation results showed that exenatide is likely to fall in a range between dominant (cost and life saving) at 20% of the US price and cost-effective (with an ICER of 22,420 pounds per QALY gained) at 100% of the US price, versus insulin glargine.

CONCLUSIONS

Based on the findings of a recent clinical trial, long-term projections indicated that exenatide is likely to be associated with improvement in life expectancy and quality-adjusted life expectancy compared to insulin glargine. The results from this modelling analysis suggest that that exenatide is likely to represent good value for money by generally accepted standards in the UK setting in individuals with type 2 diabetes inadequately controlled on oral therapy.

A comparison of twice-daily exenatide and biphasic insulin aspart in patients with type 2 diabetes who were suboptimally controlled with sulfonylurea and metformin: a non-inferiority study

AIMS/HYPOTHESIS

The aim of this 52-week, open-label, non-inferiority trial was to compare the safety and efficacy of exenatide (an incretin mimetic) with that of biphasic insulin aspart.

MATERIALS AND METHODS

Patients on metformin and a sulfonylurea were randomised to exenatide (n = 253; 5 microg twice daily for 4 weeks, 10 microg thereafter) or biphasic insulin aspart (n = 248; twice-daily doses titrated for optimal glucose control), while continuing with metformin and sulfonylurea treatment.

RESULTS

Glycaemic control achieved with exenatide was non-inferior to that achieved with biphasic insulin aspart (mean+/-SEM, HbA(1c) change: exenatide -1.04 +/- 0.07%, biphasic insulin aspart -0.89 +/- 0.06%; difference -0.15 [95% CI -0.32 to 0.01]%). Exenatide-treated patients lost weight, while patients treated with biphasic insulin aspart gained weight [between-group difference -5.4 (95% CI -5.9 to -5.0) kg]. Both treatments reduced fasting serum glucose (exenatide -1.8 +/- 0.2 mmol/l, p < 0.001; biphasic insulin aspart -1.7 +/- 0.2 mmol/l, p < 0.001). Greater reductions in postprandial glucose excursions following morning (p < 0.001), midday (p = 0.002) and evening meals (p < 0.001) were observed with exenatide. The withdrawal rate was 21.3% (54/253) for exenatide and 10.1% (25/248) for biphasic insulin aspart. Nausea (33% incidence, 3.5% discontinuation) was the most common adverse event observed with exenatide.

CONCLUSIONS/INTERPRETATION

Exenatide treatment resulted in HbA(1c) reduction similar to biphasic insulin aspart and provided better postprandial glycaemic control, making it a potential alternative for the treatment of type 2 diabetes. Treatment with biphasic insulin aspart was associated with weight gain and lower risk of adverse gastrointestinal events. Although the availability of glucose-lowering agents associated with weight reduction may be considered a therapeutic advance, the long-term implications of progressive weight reduction observed with exenatide have yet to be defined.

Exenatide

Exenatide (Byetta) is a novel, synthetic, incretin mimetic, glucoregulatory peptide approved in the US and Europe for the treatment of patients with type 2 diabetes mellitus who have inadequate glycaemic control despite receiving treatment with maximum tolerated doses of metformin and/or a sulfonylurea. In randomised, controlled, phase III trials and post hoc completer analyses in this patient population, the addition of subcutaneous exenatide twice daily significantly improved glycaemic control and was associated with progressive and significant bodyweight reduction from baseline for up to 2 years. The overall intensity of glycaemic control with exenatide was similar to that achieved with once-daily insulin glargine or twice-daily biphasic insulin aspart. Exenatide was generally well tolerated. Most adverse events were mild to moderate in severity and gastrointestinal in nature. The overall rate of hypoglycaemia was similar to rates observed with placebo (when administered with metformin) and insulin comparators (when administered with metformin and a sulfonylurea). The addition of exenatide to therapy with metformin and a sulfonylurea provided significant improvements in treatment satisfaction and patients' health-related quality of life (HR-QOL). The drug was also cost effective compared with pioglitazone, glibenclamide (glyburide), insulin glargine (all in combination with metformin and/or a sulfonylurea) and metformin alone. Overall, adjunctive therapy with exenatide is a valuable therapeutic option in patients with type 2 diabetes requiring moderate improvements in glycaemic control despite treatment with metformin and/or a sulfonylurea.

Exenatide in type 2 diabetes: treatment effects in clinical studies and animal study data

The therapeutic options for treating type 2 diabetes have been widened by the introduction of exenatide as the first incretin mimetic. Incretins are gut hormones that contribute to the stimulation of insulin secretion after a carbohydrate rich meal. The incretin hormone glucagon-like peptide-1 (GLP-1) not only stimulates insulin secretion under hyperglycaemic conditions, but also suppresses glucagon secretion, slows gastric emptying, induces satiety and improves beta cell function in type 2 diabetes. These beneficial effects have awakened the interest to use GLP-1 for the treatment of type 2 diabetes. Because of its short biological half-life, GLP-1 itself is not practical for type 2 diabetes therapy. Exenatide is a peptide found in the lizard Heloderma suspectum and has a high similarity to GLP-1. Exenatide belongs to the novel class of incretin mimetics because of its incretin-like action. It has a much longer biological half life than GLP-1 and is a GLP-1 receptor agonist that can be used for therapeutic purposes by twice daily injection. Clinical studies and clinical experience with exenatide have shown a significant reduction in HbA1c, fasting- and postprandial glucose and a marked reduction in body weight in type 2 diabetic patients. Animal studies reveal an improvement of beta cell function and an increase in beta cell mass after exenatide treatment. This review gives an overview on exenatide, its pharmacological profile and its role and potential in the therapeutic setting of type 2 diabetes. Furthermore, future developments concerning exenatide application are highlighted.

Is the metabolic syndrome a real clinical entity and should it receive drug treatment?

Metabolic syndrome represents a cluster of risk factors commonly associated with obesity and diabetes that in turn are associated with an increased risk of cardiovascular disease. The worldwide prevalence of metabolic syndrome, obesity, and diabetes is on the rise, leading to serious public health concerns surrounding the downstream consequences in the form of premature cardiovascular disease. In this review, we examine the debate surrounding the characterization and diagnosis of metabolic syndrome and discuss potential treatment options.

Patient-reported outcomes in a trial of exenatide and insulin glargine for the treatment of type 2 diabetes

Background

Patient-reported measures can be used to examine whether drug differences other than clinical efficacy have an impact on outcomes that may be important to patients. Although exenatide and insulin glargine appear to have similar efficacy for treatment of type 2 diabetes, there are several differences between the two treatments that could influence outcomes from the patient's perspective. The purpose of the current study was to examine whether the two drugs were comparable as assessed by patient-reported outcomes using data from a clinical trial in which these injectable medications were added to pre-existing oral treatment regimens.

Methods

Patients were randomized to either twice daily exenatide or once daily insulin glargine during a 26-week international trial. At baseline and endpoint, five patient-reported outcome measures were administered: the Vitality Scale of the SF-36, The Diabetes Symptom Checklist – Revised (DSC-R), the EuroQol EQ-5D, the Treatment Flexibility Scale (TFS), and the Diabetes Treatment Satisfaction Questionnaire (DTSQ). Change from baseline to endpoint was analyzed within each treatment group. Group differences were examined with General linear models (GLMs), controlling for country and baseline scores.

Results

A total of 549 patients with type 2 diabetes were enrolled in the trial, and current analyses were conducted with data from the 455 per protocol patients (228 exenatide and 227 insulin glargine). The sample was primarily Caucasian (79.6%), with slightly more men (55.2%) than women, and with a mean age of 58.5 years. Paired t-tests found that both treatment groups demonstrated statistically significant baseline to endpoint change on several of the health outcomes instruments including the DSC-R, DTSQ, and the SF-36 Vitality subscale. GLMs found no statistically significant differences between groups in change on the health outcomes instruments.

Conclusion

This analysis found that both exenatide and insulin glargine were associated with significant improvements in patient-reported outcomes when added to oral medications among patients with type 2 diabetes. Despite an additional daily injection and a higher rate of gastrointestinal adverse events, treatment satisfaction in the exenatide group was comparable to that of the glargine group, possibly because of weight reduction observed in patients treated with exenatide.

Management of Type 2 diabetes: the role of incretin mimetics

Type 2 diabetes is characterised by insulin resistance and progressive beta-cell dysfunction (which leads to hyperglycaemia), the risk of progressive worsening of glycaemic control and an increased risk of both macrovascular and microvascular complications. Existing treatment strategies target deficient insulin secretion and insulin resistance, but do not generally address the underlying progressive beta-cell dysfunction that is common to Type 2 diabetes. Traditionally, Type 2 diabetes is first treated with medical nutrition therapy (reduced food intake and increased physical activity), followed by stepwise addition of oral antidiabetes therapies and, ultimately, exogenous insulin, as required. Unfortunately, these approaches have not been shown to delay the need for additional therapies, nor do they generally prevent or delay the inexorable decline in beta-cell function. Patients with Type 2 diabetes commonly experience deterioration in glycaemic control, and may have substantial weight gain due to the diabetes therapies that contribute to worsening obesity. In addition, insulin-providing therapies, such as sulfonylureas and exogenous insulin, carry the risk of hypoglycaemia, and cannot fully address the complex hormonal irregularities that characterise Type 2 diabetes, including the role of glucagon hypersecretion. New therapeutic approaches are being developed that couple durable glycaemic control with improved control of body weight. These approaches include development of the incretin mimetics, which are a novel class of agents that share several of the glucoregulatory effects of incretin hormones, such as glucagon-like hormone-1. Deficiency of glucagon-like hormone-1 secretion is known to be present in those with abnormal glucose tolerance. Agents that manipulate the physiological actions of incretin hormones, such as glucagon-like hormone-1, may significantly benefit patients with Type 2 diabetes.

Recent evidence of sustained benefit with exenatide in Type 2 diabetes

Exenatide has been shown to improve glycaemic control (over 30 weeks) in subjects with Type 2 diabetes. A recent extension study has shown that, in metformin-treated subjects with Type 2 diabetes, exenatide remained beneficial at 82 weeks. For those subjects who completed the study, in addition to the 1% fall in glycosylated haemoglobin (HbA1c) at 30 weeks, there was another 0.2% fall in HbA1c by 82 weeks. The weight loss achieved was a mean of 3 kg after 30 weeks, and this increased to 5.3 kg after 82 weeks in the completer cohort. In another extension study, continued benefit with exenatide was shown in subjects treated with metformin and/or sulfonylureas. For those subjects who completed the study, in addition to the 0.9% fall in HbA(1c) at 30 weeks, there was another 0.2% fall in HbA(1c) by 82 weeks. The weight loss achieved was a mean of 1.6 kg after 30 weeks, and this increased to 2.1 kg after 82 weeks in the completer cohort. The subjects taking exenatide with metformin had a greater weight loss (5.3 kg), compared with those treated with a sulfonylurea (3.9 kg) and those taking metformin and a sulfonylurea (4.1 kg). In conclusion, extension studies have confirmed that exenatide is an exciting new and useful medicine for Type 2 diabetes.