Patient-reported outcomes following treatment with the human GLP-1 analogue liraglutide or glimepiride in monotherapy: results from a randomized controlled trial in patients with type 2 diabetes

Liraglutide in adults with type 2 diabetes: global perspective on safety, efficacy and patient preference

Incretin-based therapies have been gaining much attention recently as a new class of therapeutics for type 2 diabetes worldwide. Among them, glucagon-like peptide-1 receptor agonist liraglutide has been rapidly increasing its global usage. Once daily injection of liraglutide significantly ameliorates glycemic control in patients with type 2 diabetes by enhancing insulin secretion and suppressing glucagon secretion glucose-dependently. Liraglutide delays gastric emptying and suppresses food intakes, both of which contribute to glucose lowering and weight reduction. Efficacy and safety of liraglutide in management of type 2 diabetes have been well documented in several key clinical trials such as series of phase 3 Liraglutide Effect and Action in Diabetes (LEAD) trials, and the liraglutide-versus-sitagliptin trial. Recent two trials dealing with monotherapy and sulfonylurea combination therapy on Japanese patients with type 2 diabetes furthermore indicate liraglutide's effectiveness in non-obese diabetes. In this review, we summarize results from such clinical trials, and discuss efficacy and safety of liraglutide in management of type 2 diabetes in various countries, along with a pitfall of liraglutide usage in real clinical setting.

Combining basal insulin analogs with glucagon-like peptide-1 mimetics

Basal insulin analogs are recognized as an effective method of achieving and maintaining glycemic control for patients with type 2 diabetes. However, the progressive nature of the disease means that some individuals may require additional ways to maintain their glycemic goals. Intensification in these circumstances has traditionally been achieved by the addition of short-acting insulin to cover postprandial glucose excursions that are not targeted by basal insulin. However, intensive insulin regimens are associated with a higher risk of hypoglycemia and weight gain, which can contribute to a greater burden on patients. The combination of basal insulin with a glucagon-like peptide-1 (GLP-1) mimetic is a potentially attractive solution to this problem for some patients with type 2 diabetes. GLP-1 mimetics target postprandial glucose and should complement the activity of basal insulins; they are also associated with a relatively low risk of associated hypoglycemia and moderate, but significant, weight loss. Although the combination has not been approved by regulatory authorities, preliminary evidence from mostly small-scale studies suggests that basal insulins in combination with GLP-1 mimetics do provide improvements in A1c and postprandial glucose with concomitant weight loss and no marked increase in the risk of hypoglycemia. These results are promising, but further studies are required, including comparisons with basal-bolus therapy, before the complex value of this association can be fully appreciated.

Review of the therapeutic uses of liraglutide

BACKGROUND

Glucagon-like peptide (GLP-1) is a neuroendocrine hormone that increases blood glucose and is a drug target for treatment of type 2 diabetes. Liraglutide, a subcutaneous, once-daily GLP-1 agonist, is approved for the treatment of type 2 diabetes in the United States and Europe. It also has been studied for weight loss.

OBJECTIVE

The purpose of this article is to review all of the relevant literature on the chemistry, pharmacology, pharmacokinetics, metabolism, clinical trials, safety, drug interactions, cost, and place in therapy of liraglutide.

METHODS

Literature searches of MEDLINE between 1969 and September 2010, International Pharmaceutical Abstracts between 1970 and September 2010, American Diabetes Association Meeting abstracts (2008-2010), and European Association for the Study of Diabetes abstracts (2008-2010) were performed using liraglutide, Victoza, and NN2211 as key terms.

RESULTS

Thirteen randomized controlled trials were identified and summarized. Liraglutide has been shown to increase glucose-dependent insulin release by 34% to 118% and reduce postprandial glucagon levels by 20%. Studies showed that liraglutide, as monotherapy and in combination with glimepiride, metformin, and/or rosiglitazone, lowers glycosylated hemoglobin (HbA(1c)) between 0.84% and 1.5%. Transient nausea was reported by 7% to 40% of subjects. Severe hypoglycemia-glucose <55 mg/dL-was observed by 2.5% of subjects in 1 trial.

CONCLUSION

Liraglutide safely and effectively reduces HbA(1c) in patients with type 2 diabetes. The most recent American Diabetes Association guidelines recommended a GLP-1 agonist along with metformin as a second-tier therapy for type 2 diabetes. Although the American Association of Clinical Endocrinologists/American College of Endocrinologists' guidelines recommended it for first-line monotherapy in patients with HbA(1c) between 6.5% and 7.5% and with metformin if HbA(1c) is between 7.6% and 8.5%, liraglutide should be considered for patients who cannot tolerate first-line agents or if an additional agent is needed to help reach target HbA(1c) goals.

Psychological and quality of life changes in patients using GLP-1 analogues

AIMS

Using psychological and quality of life assessment tools, we prospectively studied changes in health-related quality of life and emotional well-being in patients who had commenced GLP-1 analogue therapy (exenatide) and compared them with new insulin starters.

METHODS

Two matched groups of patients with type 2 diabetes who had suboptimal glycaemic control on oral medication were assessed using a battery of well-validated psychological and quality of life tests at baseline, prior to commencement of treatment and then again after 6 months of continuous therapy, along with body mass index (BMI) and hemoglobin A1c (HbA1c) measurements.

RESULTS

In the exenatide-treated patient group (n=71), treatment satisfaction was greater (P<.05), as was the well-being score, at 6 months (P<.05), and the Hospital Anxiety and Depression Scale scores were significantly reduced (P<.05) when compared with the insulin-treated group (n=67). This was also found to be independent of changes in BMI in an analysis of covariance calculation. The effect size (using Cohen's d) of these changes was however relatively small.

CONCLUSIONS

Although exenatide and insulin appear to have similar efficacy for the treatment of type 2 diabetes mellitus, there are several differences between them that could influence outcomes from a patient's perspective. Exenatide affects both physiological and psychological parameters. 'Well-being' generally tends to improve in exenatide-treated patients and could be used as an adjunctive therapy for depression in the context of diabetes. A larger study is required to confirm these interesting findings.

Incretin-based therapy: a powerful and promising weapon in the treatment of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a progressive multisystemic disease that increases significantly cardiovascular morbidity and mortality. It is associated with obesity, insulin resistance, beta-cell dysfunction, and hyperglucagonemia, the combination of which typically leads to hyperglycemia. Incretin-based treatment modalities, and in particular glucagon-like peptide 1 (GLP-1) receptor agonists, are able to successfully counteract several of the underlying pathophysiological abnormalities of T2DM. The pancreatic effects of GLP-1 receptor agonists include glucose-lowering effects by stimulating insulin secretion and inhibiting glucagon release in a strictly glucose-dependent manner, increased beta-cell proliferation, and decreased beta-cell apoptosis. GLP-1 receptors are widely expressed throughout human body; thus, GLP-1-based therapies exert pleiotropic and multisystemic effects that extend far beyond pancreatic islets. A large body of experimental and clinical data have suggested a considerable protective role of GLP-1 analogs in the cardiovascular system (decreased blood pressure, improved endothelial and myocardial function, functional recovery of failing and ischemic heart, arterial vasodilatation), kidneys (increased diuresis and natriuresis), gastrointestinal tract (delayed gastric emptying, reduced gastric acid secretion), and central nervous system (appetite suppression, neuroprotective properties). The pharmacologic use of GLP-1 receptor agonists has been shown to reduce bodyweight and systolic blood pressure, and significantly improve glycemic control and lipid profile. Interestingly, weight reduction induced by GLP-1 analogs reflects mainly loss of abdominal visceral fat. The critical issue of whether the emerging positive cardiometabolic effects of GLP-1 analogs can be translated into better clinical outcomes for diabetic patients in terms of long-term hard endpoints, such as cardiovascular morbidity and mortality, remains to be elucidated with prospective, large-scale clinical trials.

The pharmacological treatment and management of obesity

Obesity is a pandemic with many complications that increase the societal disease burden and cost of health care, and decrease longevity and quality of life. Currently, 1 in 3 adults in the United States is obese. Physicians must therefore regularly confront obesity and its consequent diseases, and develop strategies for effective treatment and management. This article summarizes current lifestyle modifications, pharmacological treatment, and surgical options for the management of obesity and discusses the benefits, limitations, and risks of each. As insights are gained into the pathophysiology of a gut-brain neurochemical feedback axis governing satiety and feeding behavior, targets for new pharmacotherapies are being developed. In particular, gut hormone analogs are an attractive antiobesity therapy because they appear to lack the adverse effects historically associated with central nervous system-acting agents.

Liraglutide in the management of type 2 diabetes

The pathophysiology of type 2 diabetes has been attributed to the classic triad of decreased insulin secretion, increased insulin resistance, and elevated hepatic glucose production. Research has shown additional mechanisms, including incretin deficiency or resistance in the gastrointestinal tract. Liraglutide is a modified form of human glucagon-like peptide-1. Liraglutide was obtained by substitution of lysine 34 for arginine near the NH2 terminus, and by addition of a C16 fatty acid at the ɛ-amino group of lysine (at position 26) using a γ-glutamic acid spacer. Liraglutide has demonstrated glucose-dependent insulin secretion, improvements in β-cell function, deceleration of gastric emptying, and promotion of early satiety leading to weight loss. Liraglutide has the potential to acquire an important role, not only in the treatment of type 2 diabetes, but also in preservation of β-cell function, weight loss, and prevention of chronic diabetic complications.