Vildagliptin in drug-naïve patients with type 2 diabetes: a 24-week, double-blind, randomized, placebo-controlled, multiple-dose study

Dipeptidyl peptidase-4 inhibitors in the management of type 2 diabetes: safety, tolerability, and efficacy

Although glycemic control is an important and effective way to prevent and minimize the worsening of diabetes-related complications, type 2 diabetes is a progressive disease which often proves difficult to manage. Most affected patients will eventually require therapy with multiple medications in order to reach appropriate glycemic targets. The dipeptidyl peptidase-4 (DPP-4) inhibitors constitute a relatively new class of oral medications for the treatment of type 2 diabetes, which has become widely incorporated into clinical practice. This review summarizes the available data on the efficacy, safety, and tolerability of these medications.

Vildagliptin in clinical practice: a review of literature

Vildagliptin is the second member of the DPP-IV inhibitor class of drugs licensed for the treatment of type 2 diabetes mellitus (T2DM). The novel action of these drugs has promoted a new outlook in the pathobiology of T2DM. This review undertakes to examine the clinical studies published to date, with the aim of evaluating the position of vildagliptin among the drugs that are now available to treat this common dysmetabolic state.

DPP-4 inhibitors in clinical practice

Type 2 diabetes is a very common worldwide disorder, with major consequences for patients, society, and health care services. Good glycemic control is an important aspect of diabetes management because it has a significant impact on diabetes-related microvascular and possibly macrovascular complications. Based on our understanding of the pathogenesis of diabetes, multiple pharmacological interventions have been developed in the past 60 years. Although effective, none have had a lasting effect on glycemic control because of the progressive nature of type 2 diabetes requiring combination therapies and insulin treatment. In addition, several pharmacologic interventions have undesirable side effects, including hypoglycemia and weight gain. Drugs targeting the incretin pathway are the latest addition to the available antidiabetes agents. Incretin-based therapy is either delivered orally (dipeptidyl peptidase-4 [DPP-4]) inhibitors or injected subcutaneously (glucagon-like peptide-1 [GLP-1] mimetics and analogues). Dipeptidyl peptidase-4 inhibitors are effective either as a single or combination therapy in lowering glycated hemoglobin, fasting and postprandial glucose levels, with a low incidence of hypoglycemia and no weight gain. There are 3 DPP-4 inhibitors currently available (sitagliptin, saxagliptin, and vildagliptin), with more expected to be available in the future. In this article, we review the scientific background for incretin-based therapy and the available evidence regarding the role and efficacy of DPP-4 inhibitors in the treatment of patients with type 2 diabetes.

Future perspectives for insulinotropic agents in the treatment of type 2 diabetes-DPP-4 inhibitors and sulphonylureas

The introduction of dipeptidyl-peptidase IV inhibitors (DPP-4 inhibitors) brought a novel class of insulinotropic agents into the treatment options for type 2 diabetes. This paper compares the actions, clinical efficacy and safety of sulphonylureas with those of the DPP-4 inhibitors. First, the mode of action of both classes of antidiabetic agents is described. Then clinical studies for both substances in monotherapy and combination therapies are compared concerning their effects on glycaemic parameters and long-term duration of action. Hypoglycaemia incidence and other adverse effects are compared and data on cardiovascular parameters and endpoints are summarized. The effects of sulphonylureas and DPP-4 inhibitors on beta-cell function and beta-cell mass are highlighted. The present and future indications for both sulphonylureas and DPP-4 inhibitors are discussed.

Diabetes medications and body weight

Tight diabetes control sometimes comes with a price: weight gain and hypoglycemia. Two of the three major recent trials that looked at the relationship between intensive diabetes control and cardiovascular events reported significant weight gain among the intensively treated groups. There is a growing concern that the weight gain induced by most diabetes medications diminishes their clinical benefits. On the other hand, there is a claim that treating diabetes with medications that are weight neutral or induces weight loss or less weight gain while minimizing those that increase body weight may emerge as the future direction for treating overweight and obese patients with diabetes. This review clarifies the weight effect of each of the currently available diabetes medications, and explains the mechanism of action behind this effect. Despite the great variability among reviewed clinical trials, the currently available evidence is quite sufficient to demonstrate the change in body weight in association with most of the currently available medications. This review also provides some guidelines on using diabetes medications during weight management programs.

Glycaemic control in type 2 diabetes: targets and new therapies

Type 2 diabetes mellitus (T2DM) is a worldwide public health challenge. Despite the availability of many antidiabetes agents and pharmacotherapies targeting cardiovascular risk factors, the morbidity, mortality and economic consequences of T2DM are still a great burden to patients, society, health care systems and the economy. The need for new therapies for glycaemic control is compounded by the fact that existing treatments have limitations either because of their side effects (particularly weight gain and hypoglycaemia) or contraindications that limit their use. Furthermore, none of the current therapies have a significant impact on disease progression. Incretin-based therapies offer a new therapeutic approach to the management of T2DM, and there are also several even newer therapies in development. There are two groups of incretin-based therapies currently available; dipeptidyl peptidase-4 (DPP-4) inhibitors and GLP-1 analogues/mimetics. The former are given orally while the latter subcutaneously. These drugs result in glucose-dependent insulin secretion and glucose-dependent glucagon suppression, with consequent low risk of hypoglycaemia when used as mono- or combination therapy (except when used with sulphonylureas). In addition, they are either weight neutral in the case of DPP-4 inhibitors or cause weight loss in the case of incretin mimetics/analogues. Furthermore, animal studies have shown that these agents prolong beta cell survival which offers the theoretical possibility of slowing the progression to T2DM. In this article we will review the currently available antidiabetes agents with particular emphasis on incretin-based and future therapies. In addition, we will review and discuss the evidence relating to glycaemic control and cardiovascular disease.

Pharmacotherapy of hyperglycemia

Type 2 diabetes mellitus (T2DM) is a chronic, progressive disorder that affects more than 230 million people worldwide and is expected to affect 366 million by 2030. Both the prevalence of T2DM and the cost of its long term complications has driven the focus and emphasis on treatments aimed at reducing hyperglycemia and controlling hypertension and dyslipidemia. In the last 5 years new glucose lowering drugs acting on novel pathways have been developed, licensed and launched. These drugs include the glucagon-like peptide (GLP-1) agonists, exenatide, and dipeptidyl peptidase (DPP-IV) inhibitors such as sitagliptin and saxagliptin. This review describes current approaches to T2DM treatment, focusing on newer agents which tend to be associated with less hypoglycemia and possible weight loss, and addresses the potential roles of novel oral pharmacologic agents in the late-stages of development that might provide new options for the management of this disease.

Comparison of vildagliptin and thiazolidinedione as add-on therapy in patients inadequately controlled with metformin: results of the GALIANT trial--a primary care, type 2 diabetes study

AIM

To assess the efficacy and tolerability of vildagliptin compared with thiazolidinediones (TZDs) as an add on to metformin treatment in a primary care patient population with type 2 diabetes.

METHODS

This was a randomized, 12-week, open-label study comparing vildagliptin (100 mg, n = 1653) and TZD (agent and dose at the investigators' discretion, n = 825) add-on therapy in patients inadequately controlled [haemoglobin A(1C) (HbA(1c)): 7-10%] on a stable dose of metformin (> or =1000 mg/day). The primary objective was to test non-inferiority of vildagliptin to TZDs for the difference in change in HbA(1c) from baseline [established if the upper limit of the two-sided 95% confidence intervals (CI) did not exceed 0.4%].

RESULTS

Mean (+/- s.e.) change in HbA(1c) from baseline to study endpoint was -0.68 +/- 0.02% in the vildagliptin group and -0.57 +/- 0.03% in the TZD group. The difference between groups was -0.11% (95% CI: -0.17% and -0.04%), establishing the non-inferiority of vildagliptin (p = 0.001) after 3 months of treatment. Vildagliptin was non-inferior to TZDs for subgroups of race, age and body mass index. Body weight increased in the TZD group (0.33 +/- 0.11 kg) and decreased in the vildagliptin group (mean: -0.58 +/- 0.09 kg; p < 0.001 for difference). Adverse events occurred in similar proportions of patients in both groups (vildagliptin: 39.5% and TZD: 36.3%) Hypoglycaemia and abnormal changes in liver enzymes were uncommon.

CONCLUSIONS

This short-term study suggests that vildagliptin is as effective as TZDs after 3-month treatment as an add-on to metformin in a primary care population that included diverse patient subgroups.

Present and Prospective Pharmacotherapy for the Management of Patients with Type 2 Diabetes

Diabetes Mellitus is a chronic condition prevalent worldwide. Type 2 diabetes is the most common form of diabetes, comprising 90% to 95% of all cases. Over the last few decades, the importance of glycemic control and its impact on prevention of diabetes-related complications has been documented in multiple clinical trials. As most patients with type 2 diabetes will require pharmacologic intervention to achieve and maintain appropriate glycemic control, new medications targeting different aspects of the pathophysiology of type 2 diabetes have been a significant focus of research and development. During the last decade, multiple new medications for diabetes management have become available: these medications have novel mechanisms of action, differences in effectiveness, and varying side effect profiles which will be reviewed in this article. Some of these newer medications, such as the GLP-1 analogues and DPP-4 inhibitors, have become widely accepted as therapeutic options for the management of type 2 diabetes.Additional classes of glucose-lowering medications are expected to become available in the near future. This manuscript will summarize available data regarding these newer and prospective medications for the management of type 2 diabetes.

Clinical results of treating type 2 diabetic patients with sitagliptin, vildagliptin or saxagliptin--diabetes control and potential adverse events

Inhibition of dipeptidyl peptidase-4 (DPP-4) is a novel oral treatment for type 2 diabetes. DPP-4 inhibition increases insulin secretion and reduces glucagon secretion by preventing the inactivation of glucagon-like peptide-1 (GLP-1), thereby lowering glucose levels. Several DPP-4 inhibitors are in clinical development; more studies exist for sitagliptin and vildagliptin. They improve metabolic control in type 2 diabetes in monotherapy and also in combination with metformin, sulphonylurea and thiazolidinediones. HbA(1c) is reduced by approximately 0.6-1.1% in studies up to 52 weeks. Similar, although more limited, results were obtained for saxagliptin. DPP-4 inhibitors are safe and tolerable with no increased risk of adverse events compared to placebo and have a low risk of hypoglycaemia. DPP-4 inhibitors are body weight-neutral. The DPP-4 inhibitors are recommended for use in the early stage of type 2 diabetes, in combination with metformin in subjects with inadequate glycaemic control. DPP-4 inhibition may also be used in combination with sulphonylurea and thiazolidinediones and potentially also in combination with insulin. The durability and long-term safety of DPP-4 inhibitors remain to be established.

Comparison of vildagliptin and metformin monotherapy in elderly patients with type 2 diabetes: a 24-week, double-blind, randomized trial

AIMS

The study evaluated the efficacy and tolerability of the dipeptidyl peptidase-4 inhibitor, vildagliptin, and metformin in drug-naïve elderly patients with type 2 diabetes. The primary objective was to demonstrate non-inferiority of vildagliptin vs. metformin in glycated haemoglobin (HbA1c) reduction.

METHODS

This was a double-blind, randomized, multicentre, active-controlled, parallel-group study of 24-week treatment with vildagliptin (100 mg daily, n=169) or metformin (titrated to 1500 mg daily, n=166) in drug-naïve patients with type 2 diabetes aged>or=65 years (baseline HbA1c 7-9%).

RESULTS

Participants had a mean age of 71 years, known duration of diabetes of 3 years and mean baseline HbA1c of 7.7%. At end-point, vildagliptin was as effective as metformin, improving HbA1c by -0.64+/-0.07% and -0.75+/-0.07%, respectively, meeting the predefined statistical criterion for non-inferiority (upper limit of 95% confidence interval for between-treatment difference<or=0.3%). Body weight changes were -0.45+/-0.20 kg in vildagliptin-treated patients (p=0.02) and -1.25+/-0.19 kg in metformin-treated patients (p<0.001; p=0.004 vs. vildagliptin). The proportion of patients experiencing an adverse event (AE) was 44.3 vs. 50.3% in patients receiving vildagliptin and metformin respectively. Gastrointestinal (GI) AEs were significantly more frequent with metformin (24.8%) than with vildagliptin (15.0%, p=0.028), mainly driven by a 4.4-fold higher incidence of diarrhoea. A low incidence of hypoglycaemia was observed in both treatment groups (0% with vildagliptin and 1.2% with metformin).

CONCLUSIONS

Vildagliptin is an effective and well-tolerated treatment option in elderly patients with type 2 diabetes, demonstrating similar improvement in glycaemic control as metformin, with superior GI tolerability.

An Update of Recent Trials with Vildagliptin, a Dipeptidyl Peptidase-4 Inhibitor for the Treatment of Type 2 Diabetes

Objective:

To review the clinical efficacy and tolerability of vildagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor, for the treatment of type 2 diabetes, based on recent Phase 3 trials.

Data Sources:

Primary literature and review articles were obtained via a MEDLINE search (2005–November 2007) using the search terms diabetes, vildagliptin, and LAF-237. Additional data from abstracts presented at clinical meetings were included when appropriate.

Study Selection:

Nine double-blind, randomized, multicenter, parallel-group trials and vildagliptin studies were identified and reviewed.

Data Synthesis:

Vildagliptin, a selective DPP-4 inhibitor, has been shown to produce clinically significant reductions in hemoglobin A1c (A1C) levels when used as monotherapy (0.6–1%) or in combination with other glucose-lowering agents (mean decrease 0.7%). Phase 3 trials indicated a 24- to 52-week sustained effect on reduction of blood glucose in patients with type 2 diabetes. The primary endpoint for all trials was change from baseline A1C. In the intent-to-treat population, baseline A1C was compared with end-of-study A1C. More than 2,500 patients with type 2 diabetes enrolled in monotherapy trials; an additional 2,119 participated in combination therapy trials. Males outnumbered females, and all groups included obese patients. The most common adverse effects reported were nasopharyngitis, headache, and dizziness. Vildagliptin was weight-neutral and produced a rate of hypoglycemia similar to that of placebo.

Conclusions:

Vildagliptin appears to be a promising agent for the management of type 2 diabetes.

Comparison of vildagliptin and pioglitazone in patients with type 2 diabetes inadequately controlled with metformin

AIM

To compare the tolerability and efficacy of vildagliptin to pioglitazone as add-on therapy in patients with type 2 diabetes inadequately controlled with metformin monotherapy over 1-year duration.

METHODS

This 52-week, multicentre, randomized, active-controlled study compared vildagliptin (50 mg b.i.d., n = 295) and pioglitazone (30 mg daily, n = 281) in patients with inadequate glycaemic control [haemoglobin A1c (HbA(1c)) 7.5-11%] receiving a stable dose of metformin (>or=1500 mg). The primary objective was to demonstrate non-inferiority of vildagliptin at 24 weeks in the change in HbA(1c) from baseline. The objective of the additional 28 weeks of the study was to assess long-term safety, while also assessing mean change from baseline to study end in HbA(1c), fasting plasma glucose and body weight.

RESULTS

When added to a stable dose of metformin (mean baseline dose approximately 2 g/day), the non-inferiority of HbA(1c) lowering of vildagliptin to pioglitazone over 24 weeks was established at the non-inferiority margin of 0.3% (between-group difference = 0.1%). During the remaining 28 weeks, comparable HbA(1c) decreases were recorded in both groups. Overall adverse event (AE) rates were similar in both groups, as was the occurrence of peripheral oedema. Hypoglycaemia occurred rarely in both groups. Serious AEs occurred more frequently with pioglitazone group. While mean body weight increased significantly in the pioglitazone group (+2.6 kg) from baseline, there was no significant weight gain with vildagliptin (+0.2 kg).

CONCLUSIONS

When added to metformin, vildagliptin demonstrates favourable safety and tolerability over 1 year. Vildagliptin provided additional HbA(1c) lowering to that achieved with metformin alone and comparable to that achieved with pioglitazone, with only pioglitazone causing weight gain.

The backbone of oral glucose-lowering therapy: time for a paradigm shift?

The complex array of metabolic abnormalities associated with type 2 diabetes provides a number of new targets for therapeutic intervention. Although the established oral glucose-lowering therapies, metformin and the sulfonylureas, continue to provide the backbone of therapeutic approaches, the thiazolidinediones (TZDs) also play an important role. Further, a new class of oral agents, the dipeptidyl peptidase-IV (DPP-IV) inhibitors, has recently become available with apparent utility in decreasing postprandial glucose excursions. This review examines how the TZDs and the DPP-IV inhibitors might integrate into current treatment strategies, considering not only glycemic goals, but also longer-term benefits such as durability of glycemic control, effect on metabolic parameters and cardiovascular outcomes. A practical approach is taken, reflecting potential clinical situations in which therapeutic intervention is required.

Vildagliptin plus metformin combination therapy provides superior glycaemic control to individual monotherapy in treatment-naive patients with type 2 diabetes mellitus

AIM

To compare the efficacy and safety of vildagliptin and metformin initial combination therapy with individual monotherapies in treatment-naive patients with type 2 diabetes mellitus (T2DM).

METHODS

This was a 24-week, randomized, double-blind, active-controlled study. Treatment-naive patients with T2DM who had a glycated haemoglobin (HbA(1c)) of 7.5-11% (N = 1179) were randomized equally to receive vildagliptin plus high-dose metformin combination therapy (50 mg + 1000 mg twice daily), vildagliptin plus low-dose metformin combination therapy (50 mg + 500 mg twice daily), vildagliptin monotherapy (50 mg twice daily) or high-dose metformin monotherapy (1000 mg twice daily). The primary objective was to demonstrate that HbA(1c) reduction from baseline with either combination therapy is superior to both monotherapies at the week 24 endpoint. Patients who failed glycaemic-screening criteria [HbA(1c )>11% or fasting plasma glucose (FPG) >15 mmol/l (270 mg/dl)] could enter a 24-week, single-arm substudy. These patients (N = 94) received open-label vildagliptin plus high-dose metformin combination therapy (100 mg + 1000 mg twice daily).

RESULTS

From comparable baseline values (8.6-8.7%), HbA(1c) decreased in all four treatment groups, to the greatest extent with vildagliptin plus high-dose metformin combination therapy. Mean (SE) HbA(1c) change from baseline was -1.8% (0.06%), -1.6% (0.06%), -1.1% (0.06%) and -1.4% (0.06%) with vildagliptin plus high-dose metformin combination therapy, vildagliptin plus low-dose metformin combination therapy, and vildagliptin and metformin monotherapies respectively. The between-group difference was superior with vildagliptin plus high-dose metformin combination therapy (p < 0.001 vs. both monotherapies) and vildagliptin plus low-dose metformin combination therapy (p < 0.001 and p = 0.004, vs. vildagliptin and metformin monotherapies, respectively). Higher baseline HbA(1c) values were linked to greater HbA(1c) reductions, with changes of -3.2% (0.22%), -2.7% (0.22%), -1.5% (0.24%) and -2.6% (0.26%) respectively, occurring in patients with baseline HbA(1c)>or=10%. Reductions in FPG were superior with vildagliptin plus high-dose metformin combination therapy [change from baseline -2.63 (0.13) mmol/l] compared with both monotherapies [-1.26 (0.13) mmol/l and -1.92 (0.13) mmol/l, respectively; p < 0.001]. There was no incidence of hypoglycaemia or severe hypoglycaemia with either combination therapy, and neither was associated with weight gain. All treatments were well tolerated and displayed a comparable incidence of adverse events overall. Despite superior HbA(1c) lowering, the vildagliptin plus low-dose metformin combination therapy group demonstrated a favourable gastrointestinal (GI) tolerability profile compared with metformin monotherapy.

CONCLUSIONS

In treatment-naive patients, combinations of vildagliptin and both high-dose and low-dose metformin provide superior efficacy to monotherapy treatments with a comparable overall tolerability profile and low risk of hypoglycaemia. The potential dose-sparing effect of adding vildagliptin to low-dose metformin in preference to the up-titration of metformin may allow patients to achieve equivalent or superior HbA(1c) lowering without the GI tolerability issues associated with higher doses of metformin.

Study of the pharmacokinetic interaction of vildagliptin and metformin in patients with type 2 diabetes

OBJECTIVE

Metformin is widely used for treating patients with type 2 diabetes, often as first-line therapy; however, many patients with type 2 diabetes are unable to maintain adequate glycemic control with metformin alone. Vildagliptin, an orally active, potent and selective dipeptidyl peptidase IV (DPP-4) inhibitor, may represent an appropriate antihyperglycemic agent for combination with metformin to improve glycemic control in such patients. This study assessed the effects of coadministration of vildagliptin and metformin on the steady-state pharmacokinetics of each drug.

RESEARCH DESIGN AND METHODS

In this open-label, single-center, randomized, three-period, three-treatment crossover study, 17 patients with type 2 diabetes received vildagliptin 100 mg once daily; metformin 1000 mg once daily; or vildagliptin 100 mg once daily plus metformin 1000 mg once daily. Blood samples for pharmacokinetic sampling were taken frequently on the final day (Day 5) of each treatment period. Lack of pharmacokinetic interaction was defined as the ratio of geometric mean (GMR) and 90% confidence interval (CI) for combination:monotherapy being within the range 0.80-1.25.

RESULTS

Coadministration with metformin had no effect on vildagliptin AUC(0-24) (GMR, 0.94; 90% CI 0.90, 0.99) although there was an 18% decrease in vildagliptin C(max) (GMR 0.82; 90% CI 0.73, 0.91). Coadministration with vildagliptin had no effect on metformin C(max) (GMR 1.04; 90% CI 0.94, 1.16). but caused a 15% increase in AUC(0-24) (GMR 1.15; 90% CI 1.06, 1.25). Both monotherapies and combination therapy were well tolerated. Seven patients reported a total of 10 adverse events; none was serious.

CONCLUSIONS

Coadministration of vildagliptin and metformin had a small effect on the pharmacokinetics of each drug in patients with type 2 diabetes; however, this is not likely to be clinically relevant. This small, open-label trial suggests that vildagliptin could be coadministered with metformin without any dose adjustment for either agent.

Vildagliptin: a new oral treatment for type 2 diabetes mellitus

Vildagliptin is a new oral antidiabetic agent that enhances pancreatic islet cell responsiveness to glucose. An extensive clinical program involving approximately 22,000 patients and 7000 patient-years of exposure to vildagliptin has shown that the agent is well tolerated and efficacious in improving glycemic control in patients with type 2 diabetes mellitus (T2DM). Monotherapy trials have shown that significant HbA1c lowering is accompanied by body weight-neutral and lipid-neutral effects, low risk of edema, and low risk of hypoglycemia. These characteristics make vildagliptin a favorable partner for combination therapy. Studies of vildagliptin as an add-on to metformin have shown significant improvements in glycemic control (comparable to that of thiazolidinedione add-on), with the combination being well tolerated and associated with low risks for hypoglycemia and adverse effects on weight or lipid levels. Good tolerability and clinically relevant improvements in glycemic control have also been observed with vildagliptin as an add-on treatment to sulfonylurea, thiazolidinedione, or insulin treatment or in initial combination treatment with pioglitazone. Improved beta-cell function and glycemic control have been shown with vildagliptin in subjects with impaired glucose tolerance and in T2DM patients with mild hyperglycemia, with some evidence in the latter suggesting the potential for modifying disease course.

Dipeptidyl-peptidase-IV inhibition augments postprandial lipid mobilization and oxidation in type 2 diabetic patients

CONTEXT

Dipeptidyl-peptidase-IV (DPP-4) inhibition increases endogenous GLP-1 activity, resulting in improved glycemic control in patients with type 2 diabetes mellitus. The metabolic response may be explained in part by extrapancreatic mechanisms.

OBJECTIVE

We tested the hypothesis that DPP-4 inhibition with vildagliptin elicits changes in adipose tissue and skeletal muscle metabolism.

DESIGN AND SETTING

We conducted a randomized, double-blind, crossover study at an academic clinical research center.

PATIENTS

Twenty patients with type 2 diabetes, body mass index between 28 and 40 kg/m(2), participated.

INTERVENTION

INTERVENTION included 7 d treatment with the selective DPP-4 inhibitor vildagliptin or placebo and a standardized test meal on d 7.

MAIN OUTCOME MEASURES

Venous DPP-4 activity, catecholamines, free fatty acids, glycerol, glucose, (pro)insulin, dialysate glucose, lactate, pyruvate, glycerol were measured.

RESULTS

Fasting and postprandial venous insulin, glucose, glycerol, triglycerides, and free fatty acid concentrations were not different with vildagliptin and with placebo. Vildagliptin augmented the postprandial increase in plasma norepinephrine. Furthermore, vildagliptin increased dialysate glycerol and lactate concentrations in adipose tissue while suppressing dialysate lactate and pyruvate concentration in skeletal muscle. The respiratory quotient increased with meal ingestion but was consistently lower with vildagliptin.

CONCLUSIONS

Our study is the first to suggest that DPP-4 inhibition augments postprandial lipid mobilization and oxidation. The response may be explained by sympathetic activation rather than a direct effect on metabolic status.

Emerging dipeptidyl peptidase-4 inhibitors for the treatment of diabetes

Inhibition of dipeptidyl peptidase-4 (DPP-4) prevents the inactivation of glucagon-like peptide-1 (GLP-1). This increases circulating levels of active GLP-1, stimulates insulin secretion and inhibits glucagon secretion, resulting in lowering of glucose levels and improvement of glycemic control in patients with type 2 diabetes. Several DPP-4 inhibitors are emerging for therapeutic use. Most experience exists for sitagliptin, vildagliptin, saxagliptin and alogliptin. They all improve metabolic control in type 2 diabetes in monotherapy and in combination therapy with metformin, sulfonylurea and thiazolidinediones. Vildagliptin and alogliptin have also been shown to improve glycemic control when added to insulin therapy, and sitagliptin improves glycemic control in triple therapy with metformin plus thiazolidinedione. DPP-4 inhibition also shows a favorable safety profile, high tolerability, only a minimal risk of hypoglycemia, and body-weight neutrality. The main clinical indication for DPP-4 inhibitors will be in the early stage of type 2 diabetes, in combination with metformin or other treatments in subjects with inadequate glycemic control on these treatments alone. The durability and long-term safety of DPP-4 inhibition, as well as clinical positioning in relation to GLP-1 mimetics, remain now to be established.

Dipeptidyl peptidase-4 as a new target of action for type 2 diabetes mellitus: a systematic review

Type 2 diabetes mellitus is a metabolic disease leading to microvascular and macrovascular complications including coronary artery disease and stroke. Management of diabetes has been challenging, particularly in the presence of the enormous prevalence of obesity. In recent years, various inhibitors of the enzyme dipeptidyl peptidase (DPP)-4 have been developed to treat diabetes. The enzyme DPP-4 cleaves incretins, which, among other functions, stimulate insulin and suppresses glucagon. Inhibition of this enzyme results in an increase in the half-life and the sustained physiologic action of incretins, leading to an improvement in hyperglycemia. One such agent, namely sitagliptin (MK-04,310), has been introduced into the United States market, and another agent, vildagliptin (LAF237), is being used in Europe and elsewhere. This article is intended to evaluate the effectiveness of DPP-4 inhibitors as a therapeutic modality for managing type 2 diabetes. The authors conducted a literature search of various databases to identify the clinical trials involving the DPP inhibitors and concluded that the DPP-4 inhibitors, for example, sitagliptin and vildagliptin, are efficacious for managing diabetes as monotherapy or combination therapy.

Fifty-two-week efficacy and safety of vildagliptin vs. glimepiride in patients with type 2 diabetes mellitus inadequately controlled on metformin monotherapy

AIM

To examine the efficacy and safety of vildagliptin vs. glimepiride as add-on therapy to metformin in patients with type 2 diabetes mellitus in a 52-week interim analysis of a large, randomized, double-blind, multicentre study. The primary objective was to demonstrate non-inferiority of vildagliptin vs. glimepiride in glycosylated haemoglobin (HbA(1c)) reduction at week 52.

METHODS

Patients inadequately controlled on metformin monotherapy (HbA(1c) 6.5-8.5%) and receiving a stable dose of metformin (mean dose 1898 mg/day; mean duration of use 36 months) were randomized 1:1 to receive vildagliptin (50 mg twice daily, n = 1396) or glimepiride (titrated up to 6 mg/day; mean dose 4.5 mg/day, n = 1393).

RESULTS

Non-inferiority of vildagliptin was demonstrated (97.5% confidence interval 0.02%, 0.16%) with a mean (SE) change from baseline HbA(1c) (7.3% in both groups) to week 52 endpoint of -0.44% (0.02%) with vildagliptin and -0.53% (0.02%) with glimepiride. Although a similar proportion of patients reached a target HbA(1c) level of <7% with vildagliptin and glimepiride (54.1 and 55.5%, respectively), a greater proportion of patients reached this target without hypoglycaemia in the vildagliptin group (50.9 vs. 44.3%; p < 0.01). Fasting plasma glucose (FPG) reductions were comparable between groups (mean [SE] -1.01 [0.06] mmol/l and -1.14 [0.06] mmol/l respectively). Vildagliptin significantly reduced body weight relative to glimepiride (mean [SE] change from baseline -0.23 [0.11] kg; between-group difference -1.79 kg; p < 0.001) and resulted in a 10-fold lower incidence of hypoglycaemia than glimepiride (1.7 vs. 16.2% of patients presenting at least one hypoglycaemic event; 39 vs. 554 hypoglycaemic events, p < 0.01). No severe hypoglycaemia occurred with vildagliptin compared with 10 episodes with glimepiride (p < 0.01), and no patient in the vildagliptin group discontinued because of hypoglycaemia compared with 11 patients in the glimepiride group. The incidence of adverse events (AEs), serious AEs and adjudicated cardiovascular events was 74.5, 7.1 and 0.9%, respectively, in patients receiving vildagliptin, and 81.1, 9.5 and 1.6%, respectively, in patients receiving glimepiride.

CONCLUSIONS

When metformin alone fails to maintain sufficient glycaemic control, the addition of vildagliptin provides comparable efficacy to that of glimepiride after 52 weeks and displays a favourable AE profile, with no weight gain and a significant reduction in hypoglycaemia compared with glimepiride.

Vildagliptin dose-dependently improves glycemic control in Japanese patients with type 2 diabetes mellitus

OBJECTIVE

To assess the efficacy and tolerability of vildagliptin (10, 25 or 50mg bid) in Japanese patients with type 2 diabetes mellitus (T2DM).

METHODS

This 12-week, multicenter, randomized, double-blind, placebo-controlled, parallel-group study was performed in 291 patients. The primary assessment was change from baseline to endpoint in HbA1c.

RESULTS

Baseline HbA1c averaged 7.4%, and the between-treatment difference (vildagliptin-placebo) in the HbA1c adjusted mean change was -0.8%, -1.0% and -1.2% with vildagliptin 10, 25 and 50mg bid, respectively (p<0.001). Relative to baseline, body weight did not change significantly in vildagliptin groups. There was no increase in incidence of adverse events in the vildagliptin groups (62.0%, 62.5% and 61.8%, 10, 25 and 50mg bid, respectively) compared to placebo (73.6%). No deaths or drug-related serious adverse events were reported. Seven hypoglycemic events were observed (four events (n=3), two events (n=2), and one event (n=1) in the vildagliptin 10 and 50mg bid, and placebo, respectively) and none of them were severe or dose related.

CONCLUSION

Vildagliptin 50mg bid was considered to be the most effective and well-tolerated dose, and therefore can be considered the recommended clinical dose for Japanese patients with T2DM.

Emerging role of dipeptidyl peptidase-4 inhibitors in the management of type 2 diabetes

BACKGROUND

In type 2 diabetes mellitus (T2DM) there is a progressive loss of beta-cell function. One new approach yielding promising results is the use of the orally active dipeptidyl peptidase-4 (DPP-4) inhibitors. However, every new compound for T2DM has to prove long-term safety especially on cardiovascular outcomes.

OBJECTIVES

Systematic review and meta-analysis of the effects of sitagliptin and vildagliptin therapy on main efficacy parameters and safety. SELECTION CRITERIA, DATA COLLECTION, AND ANALYSIS: Randomized controlled clinical studies of at least 12 weeks' duration in T2DM.

RESULTS

DPP-4 inhibitors versus placebo showed glycosylated hemoglobin A1c (A1c) improvements of 0.7% versus placebo but not compared to monotherapy with other hypoglycemic agents (0.3% in favor of controls). The overall risk profile of DPP-4 inhibitors was low, however a 34% relative risk increase (95% confidence interval 10% to 64%, P = 0.004) was noted for all-cause infection associated with sitagliptin use. No data on immune function, health-related quality of life and diabetic complications could be extracted.

CONCLUSIONS

DPP-4 inhibitors have some theoretical advantages over existing therapies with oral antidiabetic compounds but should currently be restricted to individual patients. Long-term data on cardiovascular outcomes and safety are needed before widespread use of these new agents.

Novel Approaches to the Treatment of Type 2 Diabetes

The emergence of the glucoregulatory hormone, glucagon-like peptide-1, has expanded our understanding of glucose homeostasis. The glucoregulatory actions of glucagon-like peptide-1 include enhancement of glucose-dependent insulin secretion, suppression of inappropriately elevated glucagon secretion, slowing of gastric emptying, and reduction of food intake. Two approaches have been developed to potentiate the effects of glucagon-like peptide-1 in those with type 2 diabetes. The glucagon-like peptide-1 analogs, such as exenatide, and dipeptidyl peptidase-IV inhibitors, such as sitagliptin, are currently available whereas others are in the final stages of development. These agents effectively reduce hemoglobin A1c while providing the other benefits associated with increased glucagon-like peptide-1. They also offer the potential to preserve the β-cell function. The effects on cardiovascular disease, if any, are unknown. Based on the current evidence, these agents represent viable second-and third-line options in the management of type 2 diabetes.

Efficacy and safety of adding the dipeptidyl peptidase-4 inhibitor alogliptin to metformin therapy in patients with type 2 diabetes inadequately controlled with metformin monotherapy: a multicentre, randomised, double-blind, placebo-controlled study

AIMS

To evaluate the efficacy and safety of alogliptin, a new dipeptidyl peptidase-4 inhibitor, for 26 weeks at once-daily doses of 12.5 and 25 mg in combination with metformin in patients whose HbA(1c) levels were inadequately controlled on metformin alone.

METHODS AND PATIENTS

Patients with type 2 diabetes and inadequate glycaemic control (HbA(1c) 7.0-10.0%) were randomised to continue a stable daily metformin dose regimen (> or = 1500 mg) plus the addition of placebo (n = 104) or alogliptin at once-daily doses of 12.5 (n = 213) or 25 mg (n = 210). HbA(1c), insulin, proinsulin, C-peptide and fasting plasma glucose (FPG) concentrations were determined over a period of 26 weeks.

RESULTS

Alogliptin at either dose produced least squares mean (SE) decreases from baseline in HbA(1c) of -0.6 (0.1)% and in FPG of -17.0 (2.5) mg/dl [-1.0 (0.1) mmol/l], decreases that were significantly (p < 0.001) greater than those observed with placebo. The between treatment differences (alogliptin - placebo) in FPG reached statistical significance (p < 0.001) as early as week 1 and persisted for the duration of the study. Overall, adverse events (AEs) observed with alogliptin were not substantially different from those observed with placebo. This includes low event rates for gastrointestinal side effects and hypoglycaemic episodes. There was no dose-related pattern of AE reporting between alogliptin groups and few serious AEs were reported.

CONCLUSION

Alogliptin is an effective and safe treatment for type 2 diabetes when added to metformin for patients not sufficiently controlled on metformin monotherapy.

Incretin-based therapies in type 2 diabetes: a review of clinical results

GLP-1 analogues (incretin mimetics) and DPP-4 inhibitors (incretin enhancers) represent new classes of anti-diabetic agents for the treatment of type 2 diabetes. The efficacy and safety of the incretin mimetic exenatide and of the DPP-4 inhibitors, sitagliptin and vildagliptin, have been clearly demonstrated by a very large number of clinical trials. Efficacy was demonstrated in terms of reduction of HbA1c, fasting and postprandial glucose. Moreover, exenatide showed a favourable effect on weight, while DPP-4 inhibitors were neutral with respect to this outcome. The low rate of hypoglycemic events seen in all studies confirms the glucose dependent action of incretins.

Efficacy and safety of the dipeptidyl peptidase-4 inhibitor alogliptin in patients with type 2 diabetes and inadequate glycemic control: a randomized, double-blind, placebo-controlled study

OBJECTIVE

To evaluate the dipeptidyl peptidase-4 (DPP-4) inhibitor alogliptin in drug-naïve patients with inadequately controlled type 2 diabetes.

RESEARCH DESIGN AND METHODS

This double-blind, placebo-controlled, multicenter study included 329 patients with poorly controlled diabetes randomized to once-daily treatment with 12.5 mg alogliptin (n = 133), 25 mg alogliptin (n = 131), or placebo (n = 65) for 26 weeks. Primary efficacy end point was mean change from baseline in A1C at the final visit.

RESULTS

At week 26, mean change in A1C was significantly greater (P < 0.001) for 12.5 mg (-0.56%) and 25 mg (-0.59%) alogliptin than placebo (-0.02%). Reductions in fasting plasma glucose were also greater (P < 0.001) in alogliptin-treated patients than in those receiving placebo. Overall, incidences of adverse events (67.4-70.3%) and hypoglycemia (1.5-3.0%) were similar across treatment groups.

CONCLUSIONS

Alogliptin monotherapy was well tolerated and significantly improved glycemic control in patients with type 2 diabetes, without raising the incidence of hypoglycemia.

Evidence that vildagliptin attenuates deterioration of glycaemic control during 2-year treatment of patients with type 2 diabetes and mild hyperglycaemia

AIM

To assess the 2-year efficacy and tolerability of vildagliptin (50 mg once daily) in patients with type 2 diabetes (T2DM) and mild hyperglycaemia.

METHODS

This was a multicentre, randomized, double-blind, placebo-controlled trial comprising a 52-week core study with a 4-week, active treatment-free washout followed by a 52-week extension study with another washout period conducted in 131 drug-naïve patients with T2DM and mild hyperglycaemia [glycosylated haemoglobin (HbA(1c)) 6.2-7.2%]. All patients received lifestyle counselling at each study visit. Efficacy and tolerability were assessed during visits at weeks 0 (core study baseline), 4, 8, 12, 16, 24, 32, 40 and 52 of active treatment; at week 56 (i.e. after the first washout period); at weeks 68, 80, 96 and 108 and at week 112 (i.e. after the second washout period). Standard meal tests were also performed at weeks 0, 24, 52, 56, 80, 108 and 112 to assess postprandial glycaemia and beta-cell function, which was quantified by glucose area under the curve (AUC(0-2) (h))/insulin secretory rate (ISR) AUC(0-2) (h) (ISR/G). Changes from baseline and between-treatment differences (placebo-adjusted changes from baseline during vildagliptin treatment) were analysed by ancova.

RESULTS

The placebo-adjusted change from week 0 in HbA(1c) was -0.3 +/- 0.1% after 1 year of vildagliptin treatment (p < 0.001) and -0.5 +/- 0.2% after 2 years (p = 0.008). The placebo-adjusted change from core study baseline in fasting plasma glucose, in glucose AUC(0-2) (h) and in the beta-cell function parameter, ISR/G, tended to be greater after 2 years than after 1 year of treatment with vildagliptin. Even after a 4-week washout, the placebo-adjusted change from week 0 to week 112 in ISR/G was 3.2 +/- 1.6 pmol/min/m(2)/mM (p = 0.058) and the placebo-adjusted difference in the change from week 0 to week 112 in HbA(1c) was -0.3 +/- 0.1% (p = 0.051). The incidences of adverse events (AEs), serious AEs and discontinuations because of AEs were similar in the two treatment groups, and hypoglycaemic episodes were reported by no patient receiving vildagliptin and by two patients receiving placebo.

CONCLUSIONS

In drug-naïve patients with mild hyperglycaemia, 2-year treatment with vildagliptin 50 mg once daily attenuated the progressive loss of glycaemic control seen in patients receiving only lifestyle counselling (and placebo). This appears to be because of a corresponding attenuation of the deterioration of beta-cell function as assessed by ISR/G.

GLP-1: physiological effects and potential therapeutic applications

Glucagon-like peptide 1 (GLP-1) is a gut-derived incretin hormone with the potential to change diabetes. The physiological effects of GLP-1 are multiple, and many seem to ameliorate the different conditions defining the diverse physiopathology seen in type 2 diabetes. In animal studies, GLP-1 stimulates beta-cell proliferation and neogenesis and inhibits beta-cell apoptosis. In humans, GLP-1 stimulates insulin secretion and inhibits glucagon and gastrointestinal secretions and motility. It enhances satiety and reduces food intake and has beneficial effects on cardiovascular function and endothelial dysfunction. Enhancing incretin action for therapeutic use includes GLP-1 receptor agonists resistant to degradation (incretin mimetics) and dipeptidyl peptidase (DPP)-4 inhibitors. In clinical trials with type 2 diabetic patients on various oral antidiabetic regimes, both treatment modalities efficaciously improve glycaemic control and beta-cell function. Whereas the incretin mimetics induce weight loss, the DPP-4 inhibitors are considered weight neutral. In type 1 diabetes, treatment with GLP-1 shows promising effects. However, several areas need clinical confirmation: the durability of the weight loss, the ability to preserve functional beta-cell mass and the applicability in other than type 2 diabetes. As such, long-term studies and studies with cardiovascular end-points are needed to confirm the true benefits of these new classes of antidiabetic drugs in the treatment of diabetes mellitus.

Effects of vildagliptin on glucose control in patients with type 2 diabetes inadequately controlled with a sulphonylurea

AIM

To compare the efficacy and tolerability of vildagliptin vs. placebo in patients with type 2 diabetes mellitus (T2DM) who are inadequately controlled [haemoglobin A(1c) (HbA(1c)) 7.5 to 11%] with prior sulphonylurea (SU) monotherapy.

METHODS

This 24-week, multicentre, randomized, double-blind, placebo-controlled study assessed the effects of the dipeptidyl peptidase-4 inhibitor vildagliptin (50 mg given once or twice daily) vs. placebo added to glimepiride (4 mg once daily) in 515 patients with T2DM. Adjusted mean changes from baseline to end-point (AMDelta) in HbA(1c), fasting plasma glucose, fasting lipids and body weight were compared by analysis of covariance.

RESULTS

The between-group difference (vildagliptin - placebo) in AMDelta HbA(1c) was -0.6 +/- 0.1% in patients receiving vildagliptin 50 mg daily and -0.7 +/- 0.1% in those receiving 100 mg daily (p < 0.001 vs. placebo for both). Greater efficacy was seen in patients > or =65 years of age (-0.7 +/- 0.1% and -0.8 +/- 0.2% for 50 and 100 mg daily respectively) and in patients with baseline HbA(1c) > 9% (Delta = -1.0 +/- 0.2% and -0.9 +/- 0.2% for 50 and 100 mg daily respectively). Relative to placebo, patients receiving vildagliptin also had improvements in beta-cell function and postprandial glucose, with small changes in fasting lipids and body weight. The incidences of adverse events (AEs) (67.1, 66.3 and 64.2%) and serious AEs (2.9, 2.4 and 5.1%) were similar in patients receiving 50 mg vildagliptin, 100 mg vildagliptin or placebo respectively. The incidence of hypoglycaemic events was low but slightly higher in the group receiving vildagliptin 100 mg (3.6%) than in the group receiving vildagliptin 50 mg (1.2%) or placebo (0.6%).

CONCLUSIONS

In patients with T2DM inadequately controlled with prior SU monotherapy, addition of vildagliptin (50 or 100 mg daily) to glimepiride (4 mg once daily) improves glycaemic control and is well tolerated. Addition of vildagliptin 50 mg daily to SU monotherapy may be a particularly attractive therapy in elderly patients.

Incretin-based therapies in type 2 diabetes mellitus

CONTEXT

Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide are incretins secreted from enteroendocrine cells postprandially in part to regulate glucose homeostasis. Dysregulation of these hormones is evident in type 2 diabetes mellitus (T2DM). Two new drugs, exenatide (GLP-1 mimetic) and sitagliptin [dipeptidyl peptidase (DPP) 4 inhibitor], have been approved by regulatory agencies for treating T2DM. Liraglutide (GLP-1 mimetic) and vildagliptin (DPP 4 inhibitor) are expected to arrive on the market soon.

EVIDENCE ACQUISITION

The background of incretin-based therapy and selected clinical trials of these four drugs are reviewed. A MEDLINE search was conducted for published articles using the key words incretin, glucose-dependent insulinotropic polypeptide, GLP-1, exendin-4, exenatide, DPP 4, liraglutide, sitagliptin, and vildagliptin.

EVIDENCE SYNTHESIS

Exenatide and liraglutide are injection based. Three-year follow-up data on exenatide showed a sustained weight loss and glycosylated hemoglobin (HbA(1c)) reduction of 1%. Nausea and vomiting are common. Results from phase 3 studies are pending on liraglutide. Sitagliptin and vildagliptin are orally active. In 24-wk studies, sitagliptin reduces HbA(1c) by 0.6-0.8% as monotherapy, 1.8% as initial combination therapy with metformin, and 0.7% as add-on therapy to metformin. Vildagliptin monotherapy lowered HbA(1c) by 1.0-1.4% after 24 wk. Their major side effects are urinary tract and nasopharyngeal infections and headaches. Exenatide and liraglutide cause weight loss, whereas sitagliptin and vildagliptin do not.

CONCLUSIONS

The availability of GLP-1 mimetics and DPP 4 inhibitors has increased our armamentarium for treating T2DM. Unresolved issues such as the effects of GLP-1 mimetics and DPP 4 inhibitors on beta-cell mass, the mechanism by which GLP-1 mimetics lowers glucagon levels, and exactly how DPP 4 inhibitors lead to a decline in plasma glucose levels without an increase in insulin secretion, need further research.

Robust improvements in fasting and prandial measures of beta-cell function with vildagliptin in drug-naïve patients: analysis of pooled vildagliptin monotherapy database

AIM

To assess the effects of 24-week treatment with vildagliptin on measures of beta-cell function in a broad spectrum of drug-naïve patients with type 2 diabetes (T2DM).

METHODS

Data from all double-blind, multicentre, randomized, placebo- or active-controlled trials conducted in drug-naïve patients with T2DM were pooled from all patients receiving monotherapy with vildagliptin (100 mg daily: 50 mg twice daily or 100 mg once daily, n = 1855) or placebo (n = 347). Fasting measures of beta-cell function [homeostasis model assessment of beta-cell function (HOMA-B) and proinsulin : insulin ratio] were assessed in the overall pooled monotherapy population. Standard meal tests were performed at baseline and week 24 in a subset of patients, and effects of vildagliptin (100 mg daily, n = 227) on dynamic (meal test-derived) measures of beta-cell function [insulin secretion rate relative to glucose (ISR/G) and insulinogenic indices] were assessed relative to baseline and vs. placebo (n = 29).

RESULTS

In the overall population, vildagliptin significantly increased HOMA-B both relative to baseline [adjusted mean change (AMDelta) = 10.3 +/- 1.5] and vs. placebo (between-treatment difference in AMDelta = 11.5 +/- 4.5, p = 0.01) and significantly decreased the proinsulin : insulin ratio relative to baseline (AMDelta = -0.05 +/- 0.01) and vs. placebo (between-treatment difference in AMDelta = -0.09 +/- 0.02, p < 0.001). Relative to baseline, vildagliptin monotherapy significantly increased all meal test-derived parameters, and ISR/G (between-treatment difference in AMDelta = 9.8 +/- 2.8 pmol/min/m(2)/mM, p < 0.001) and the insulinogenic index(0-peak glucose) (between-treatment difference in AMDelta = 0.24 +/- 0.05 pmol/mmol, p = 0.045) were significantly increased vs. placebo.

CONCLUSIONS

Vildagliptin monotherapy consistently produced robust improvements in both fasting and meal test-derived measures of beta-cell function across a broad spectrum of drug-naïve patients with T2DM. All Phase III trials described (NCT 00099905, NCT 00099866, NCT 00099918, NCT 00101673, NCT 00101803 and NCT 00120536) are registered with ClinicalTrials.gov.

DPP-4 inhibitors and GLP-1 analogues: for whom? Which place for incretins in the management of type 2 diabetic patients?

This review tries to delineate how to insert the GLP-1 based agents, DPP4-inhibitors (sitagliptin and vildagliptin) and GLP-1 analogues (exenatide and liraglutide), in the guidelines and the daily practice for the management of type 2 diabetes (T2DM). Orally administered DPP-4 inhibitors reduce HbA(1c) by 0.5-1.1%, without hypoglycaemic events and no weight gain. The subcutaneous injected GLP-1 analogues show larger reductions in HbA(1c) by 0.8-1.7% and a weight loss (1.75-3.8 kg) with most gastrointestinal common adverse events contributing to a significant treatment interruption. Regarding the efficacy, the cost and the safety of these drugs they will no challenge the use of metformin as the initial therapy of T2DM. In patients'not tolerating metformin or in older patients, DPP-4 inhibitors seem to be an excellent alternative monotherapy. Several studies argue in favour of the use of DPP-4 inhibitors in combination with metformin as a promising second line treatment. This combination offers advantages when compared to others currently used, particularly if one considers the more stringent guidelines with a higher risk of hypoglycaemic events in patient receiving sulfonylureas and mild hyperglycaemia or weight gain with thiazolidinedione (TZD). Oral triple therapy, metformin + TZD + incretin-based drug, has several theoretical advantages but is not supported by any published trial. Finally, obtaining the acceptance of injections once to twice daily vs. oral administration of OADs will probably remain difficult during the first years of treatment in many patients. Nevertheless a long-acting release exenatide formulation (i.e. once weekly), for subcutaneous injection in patients with type 2 diabetes under development shows promising preliminary results. If confirmed, the use of this new class of drugs should be largely developed from monotherapy to combinations (bitherapy or tritherapy), and even instead of insulin or in association with insulin. The long-term effect of GLP-1 based agents on glycaemic control has not yet been established, and their potential impact on beta-cell function in humans remains an area of active investigation. So, further studies are required and will allow progressively determining the use of incretin-based agents in T2DM treatment strategy. Their efficacy, safety and their cost vs. older strategies, will be really evaluated by physicians in the real daily practice and by large and long term systematic surveys, as recently shown in other therapeutic fields.

Therapeutic approach of type 2 diabetes mellitus with GLP-1 based therapies

The goal of this review is to think about how to incorporate the GLP-1 based agents, represented by the dipeptidyl peptidase-4 (DPP-4) inhibitors or the glucagon-like peptide-1 (GLP-1) analogs, in the guidelines for the management of type 2 diabetes (T2DM). Orally administered DPP-4 inhibitors, such as sitagliptin and vildagliptin, reduce HbA(1c) (absolute values) by 0.5-1.1% (5 to 12%, relative values), with few adverse events and no weight gain. The sub-cutaneous injected GLP-1 analogs show larger reductions in HbA(1c) (0.8-1.7%, absolute values; 9.4-20.0%, relative values), associated with weight loss (1.75-3.8 kg); their most common adverse events are gastrointestinal symptoms which contribute to a substantial treatment interruption. If they do not challenge the use of metformin as the initial therapy of T2DM, several studies argue in favour of the use of DPP-4 inhibitors, either in combination with metformin as the initial treatment or, in add-on therapy to metformin. The advantages of this combination over others currently used are reviewed. In patients not tolerating metformin, DPP-4 inhibitors seem to be an excellent alternative as a monotherapy. As long as oral triple therapy is concerned, the choice for the association metformin + thiazolidinedione + incretin-based drug, has again several theoretical advantages against other triple therapy combinations. Finally, in patients with T2DM inadequately controlled with maximal tolerated oral multi-therapies, GLP-1 agonists are a good alternative to insulin therapy, allowing reaching a better glycaemic control together with a weight loss. However, for patients who do not tolerate GLP-1 agonist treatment, and for those not reaching the HbA(1c) target, insulin will remain necessary, allowing getting a better metabolic control, with few adverse events. The long-term effect of these new agents on glycaemic control has not yet been established, and their potential impact on beta-cell function in humans remains an area of active investigation. So, further studies are needed and will allow progressively refining the use of incretin-based agents in T2DM treatment strategy.

Efficacy and tolerability of vildagliptin in drug-naïve patients with type 2 diabetes and mild hyperglycaemia*

AIM

This study was conducted to assess efficacy and tolerability of vildagliptin in drug-naïve patients with type 2 diabetes and mild hyperglycaemia.

METHODS

Multicentre, double-blind, randomized, placebo-controlled, parallel-group study of 52-week treatment with vildagliptin (50 mg q.d.) in 306 drug-naïve patients with type 2 diabetes (A1C = 6.2-7.5%). A1C, fasting plasma glucose (FPG) and measures of prandial glucose control and beta-cell function determined during standard meal tests were assessed.

RESULTS

Baseline A1C and FPG averaged 6.7% and 7.1 mmol/l, respectively, in patients randomized to vildagliptin (n = 156) and 6.8% and 7.2 mmol/l in those randomized to placebo (n = 150). A1C decreased modestly in vildagliptin-treated patients (Delta = -0.2 +/- 0.1%) and increased in patients receiving placebo (Delta = 0.1 +/- 0.1%). The between-group difference (vildagliptin - placebo) in adjusted mean change (AM Delta) in A1C was -0.3 +/- 0.1% (p < 0.001). FPG increased in patients receiving placebo (Delta = 0.5 +/- 0.1 mmol/l) and to a significantly lesser extent in vildagliptin-treated patients (between-group difference in AM Delta FPG = -0.4 +/- 0.2 mmol/l, p = 0.032). Relative to placebo, 2-h postprandial glucose (PPG) decreased (-0.9 +/- 0.4 mmol/l, p = 0.012), and insulin secretory rate (ISR) relative to glucose [ISR area under the curve (AUC)(0-2) (h)/glucose AUC(0-2) (h)] increased (+5.0 +/- 1.2 pmol/min/m(2)/mM, p < 0.001). Mean body weight decreased by 0.5 +/- 0.3 kg in vildagliptin-treated patients and by 0.2 +/- 0.3 kg in patients receiving placebo. The side-effect profile of vildagliptin was similar to that of placebo, and one hypoglycaemic episode occurred in one patient receiving placebo.

CONCLUSIONS

In drug-naïve patients with mild hyperglycaemia, relative to placebo, 52-week treatment with vildagliptin 50 mg q.d. significantly decreases A1C, FPG and PPG and improves beta-cell function without weight gain or hypoglycaemia.

Incretin mimetics and dipeptidyl peptidase-4 inhibitors: innovative treatment therapies for type 2 diabetes

The prevalence of diabetes and impaired glucose tolerance is predicted to dramatically increase over the next two decades. Clinical therapies for type 2 diabetes mellitus (T2DM) have traditionally included lifestyle modification, oral anti-diabetic agents, and ultimately insulin initiation. In this report, we review the clinical trial results of two innovative T2DM treatment therapies that are based on the glucoregulatory effects of incretin hormones. Incretin mimetics are peptide drugs that mimic several of the actions of glucagon-like peptide-1 (GLP-1) and have been shown to lower glycated hemoglobin (A1C) levels in patients with T2DM. Additionally, incretin mimetics lower postprandial and fasting glucose, suppress elevated glucagon release, and are associated with progressive weight reduction. Dipeptidyl peptidase-4 (DPP-4) inhibitors increase endogenous GLP-1 levels by inhibiting the enzymatic degradation of GLP-1. Clinical studies in patients with T2DM have shown that DPP-4 inhibitors reduce elevated A1C, lower postprandial and fasting glucose, suppress glucagon release, and are weight neutral. Collectively, these new drugs, given in combination with other antidiabetic agents, such as metformin, sulfonylureas, and/or thiazolidinediones, can help restore glucose homeostasis in poorly controlled patients with T2DM.

Evolving concepts of type 2 diabetes management with oral medications: new approaches to an old disease

BACKGROUND

Type 2 diabetes is often accompanied by co-morbid conditions such as hypertension and dyslipidemia, which, coupled with persistent hyperglycemia, result in significant macrovascular and microvascular complications. Type 2 diabetes treatments focus primarily on controlling hyperglycemia, hypertension, and dyslipidemia to stabilize the disease and minimize complications. Despite treatment, control of hyperglycemia and the conditions associated with type 2 diabetes are suboptimal in the majority of patients. Research efforts have concentrated on the development of new therapies for type 2 diabetes, including agents that could be used both as monotherapy and in combination with established oral antidiabetic agents to improve glycemic control and reduce the disease burden on patients.

OBJECTIVE

To review published literature on oral agents in development for type 2 diabetes, with a focus on their mechanism of action and impact on concomitant risk factors.

METHODS

After identifying oral agents in late-stage development for type 2 diabetes using the R&D Insight database, a literature review was conducted through PubMed for studies (preferably randomized, controlled trials) on dipeptidyl peptidase-IV inhibitors, CB(1) cannabinoid receptor blockers, and bile acid sequestrants. Where limited published data were available, abstracts from recent major conferences were searched. Other emerging therapies targeting pathways involved in modifying insulin resistance, glycogenolysis, and gluconeogenesis are also discussed.

CONCLUSIONS

A variety of novel therapies for type 2 diabetes are in development, which will provide patients and diabetes care providers more choices for the management of this disease. Importantly, many of these treatments offer the potential to significantly improve multiple metabolic parameters.

Beyond insulin replacement: addressing the additional needs of the diabetes patient

The management of type 2 diabetes mellitus (T2DM) typically focuses on correcting dysglycaemia to reduce risk for microvascular and macrovascular complications, possibly by reducing glucose-mediated oxidative stress. However, other cardiometabolic risk factors, including abdominal obesity and dyslipidaemia are often overlooked in the quest for perfect glucose control. The currently used antidiabetic agents, including insulin, metformin, sulphonylureas and thiazolidinediones, have limited efficacy on these risk factors. A number of new therapeutic agents are undergoing clinical development, including glucagon-like peptide 1 mimetics (exenatide and liraglutide) and dipeptidyl peptidase 4 inhibitors (sitagliptin and vildagliptin), which target the incretin system, and the cannabinoid-1 receptor antagonists (rimonabant), which target the endocannabinoid system, may hold some promise for meeting these unmet needs. In this review, the clinical properties of these agents and potential treatment pathways to best use these agents are discussed for improving the management of T2DM and cardiovascular risk.

Glucagon-like peptide receptor agonists and dipeptidyl peptidase-4 inhibitors in the treatment of diabetes: a review of clinical trials

PURPOSE OF REVIEW

To discuss the virtues and shortcomings of the glucagon-like peptide-1 receptor agonists and the dipeptidyl peptidase-4 inhibitors in the treatment of type 2 diabetes.

RECENT FINDINGS

The injectable glucagon-like peptide-1 receptor agonists exenatide significantly improves glycaemic control, with average reductions in haemoglobin A1c of about 1.0%, fasting plasma glucose of about 1.4 mmol/l, and causes a weight loss of approximately 2-3 kg after 30 weeks of treatment in patients with type 2 diabetes. The adverse effects are transient nausea and vomiting. The long-acting glucagon-like peptide-1 receptor agonists liraglutide and exenatide long-acting release reduce haemoglobin A1c by about 1.0-2.0% and have fewer gastrointestinal side-effects. The orally available dipeptidyl peptidase-4 inhibitors, that is sitagliptin and vildagliptin reduce haemoglobin A1c by 0.5-1.0%, are weight neutral and without gastrointestinal side-effects.

SUMMARY

The benefits and position of the glucagon-like peptide-1 analogues and the dipeptidyl peptidase-4 inhibitors in the diabetes treatment algorithm will be clarified when we have long-term trials with hard cardiovascular endpoints and data illustrating the effects on the progression of type 2 diabetes.

Vildagliptin: the evidence for its place in the treatment of type 2 diabetes mellitus

INTRODUCTION

Type 2 diabetes is increasing in prevalence worldwide and is a leading cause of morbidity and mortality, mainly due to the development of complications. Vildagliptin is an inhibitor of dipeptidyl peptidase 4 (DPP-4), a new class of oral antidiabetic agents.

AIMS

To evaluate the role of vildagliptin in the management of type 2 diabetes.

EVIDENCE REVIEW

Clear evidence shows that vildagliptin improves glycemic control (measured by glycosylated hemoglobin and blood glucose levels) more than placebo in adults with type 2 diabetes, either as monotherapy or in combination with metformin. Vildagliptin is as effective as pioglitazone and rosiglitazone, and slightly less effective than metformin, although better tolerated. Further glycemic control is achieved when adding vildagliptin to metformin, pioglitazone, or glimepride. There is evidence that vildagliptin improves beta-cell function and insulin sensitivity. Vildagliptin does not appear to be associated with weight gain or with a higher risk of hypoglycemia than placebo or other commonly used oral antidiabetic agents. Economic evidence is currently lacking.

PLACE IN THERAPY

Vildagliptin improves glycemic control with little if any weight gain or hypoglycemia in adult patients with type 2 diabetes when given alone or in combination with metformin, thiazolidinediones, or sulfonylureas. Since many diabetic patients require combination therapy, the complementary mechanism of action of vildagliptin and other commonly prescribed antidiabetic drugs represents an important new therapeutic option in diabetes management.

Dipeptidyl peptidase-4 (DPP-4) inhibitors for type 2 diabetes mellitus

BACKGROUND

In type 2 diabetes mellitus there is a progressive loss of beta-cell function. One new approach yielding promising results is the use of the orally active dipeptidyl peptidase-4 (DPP-4) inhibitors like sitagliptin and vildagliptin.

OBJECTIVES

To assess the effects of dipeptidyl peptidase-4 (DPP-4) inhibitors for type 2 diabetes mellitus.

SEARCH STRATEGY

Studies were obtained from computerised searches of MEDLINE, EMBASE and The Cochrane Library.

SELECTION CRITERIA

Studies were included if they were randomised controlled trials in adult people with type 2 diabetes mellitus and had a trial duration of at least 12 weeks.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed risk of bias and extracted data. Pooling of studies was performed by means of fixed-effect meta-analysis.

MAIN RESULTS

Twenty-five studies of good quality were identified, 11 trials evaluated sitagliptin and 14 trials vildagliptin treatment. Altogether, 6743 patients were randomised in sitagliptin and 6121 patients in vildagliptin studies, respectively. Sitagliptin and vildagliptin studies ranged from 12 to 52 weeks duration. No data were published on mortality, diabetic complications, costs of treatment and health-related quality of life. Sitagliptin and vildagliptin therapy in comparison with placebo resulted in an HbA1c reduction of approximately 0.7% and 0.6%, respectively. Data on comparisons with active comparators were limited but indicated no improved metabolic control following DPP-4 intervention in contrast to other hypoglycaemic agents. Sitagliptin and vildagliptin therapy did not result in weight gain but weight loss was more pronounced following placebo interventions. No definite conclusions could be drawn from published data on sitagliptin and vildagliptin effects on measurements of beta-cell function. Overall, sitagliptin and vildagliptin were well tolerated, no severe hypoglycaemia was reported in patients taking sitagliptin or vildagliptin. All-cause infections increased significantly after sitagliptin treatment but did not reach statistical significance following vildagliptin therapy. All published randomised controlled trials of at least 12 weeks treatment with sitagliptin and vildagliptin only reported routine laboratory safety measurements

AUTHORS' CONCLUSIONS

DPP-4 inhibitors have some theoretical advantages over existing therapies with oral antidiabetic compounds but should currently be restricted to individual patients. Long-term data especially on cardiovascular outcomes and safety are urgently needed before widespread use of these new agents. More information on the benefit-risk ratio of DPP-4 inhibitor treatment is necessary especially analysing adverse effects on parameters of immune function. Also, long-term data are needed investigating patient-oriented parameters like health-related quality of life, diabetic complications and all-cause mortality.

Comparison of vildagliptin and acarbose monotherapy in patients with Type 2 diabetes: a 24-week, double-blind, randomized trial

AIMS

To compare the efficacy and tolerability of the dipeptidyl peptidase-4 inhibitor, vildagliptin, with the alpha glucosidase inhibitor, acarbose, in drug-naive patients with Type 2 diabetes.

METHODS

This multi-centre, randomized, double-blind, parallel-arm study compared the efficacy and tolerability of vildagliptin (100 mg daily, given as 50 mg twice daily, n = 441) and acarbose (up to 300 mg daily, given as three equally divided doses, n = 220) during 24-week treatment in drug-naive patients with Type 2 diabetes.

RESULTS

Monotherapy with vildagliptin or acarbose decreased glycated haemoglobin (HbA(1c)) (baseline approximately 8.6%) to a similar extent during 24-week treatment. The adjusted mean change from baseline to end-point (AMDelta) in HbA(1c) was -1.4 +/- 0.1% and -1.3 +/- 0.1% in patients receiving vildagliptin and acarbose, respectively, meeting the statistical criterion for non-inferiority (upper limit of 95% confidence interval for between-treatment difference < or = 0.4%). The decrease in fasting plasma glucose was similar with acarbose (-1.5 +/- 0.2 mmol/l) and vildagliptin (-1.2 +/- 0.1 mmol/l). Body weight did not change in vildagliptin-treated patients (-0.4 +/- 0.1 kg) but decreased in acarbose-treated patients (-1.7 +/- 0.2 kg, P < 0.001 vs. vildagliptin). The proportion of patients experiencing any adverse event (AE) was 35% vs. 51% in patients receiving vildagliptin or acarbose, respectively; gastrointestinal AEs were significantly more frequent with acarbose (25.5%) than vildagliptin (12.3%, P < 0.001). No hypoglycaemia was reported for either group.

CONCLUSIONS

Vildagliptin is effective and well tolerated in patients with Type 2 diabetes, demonstrating similar glycaemic reductions to acarbose, but with better tolerability.

Management of type 2 diabetes in the obese patient: current concerns and emerging therapies

OBJECTIVES

The aims of this review are (1) to examine the pathophysiologic relationship between type 2 diabetes and obesity, (2) to provide an overview of current and emerging treatments for type 2 diabetes and their effects on body weight.

METHODS

A MEDLINE search was performed for literature published in the English language from 1966 to 2006. Abstracts and presentations from the American Diabetes Association Scientific Sessions (2002-2006) and the European Association for the Study of Diabetes Annual Meetings (1998-2006) were also searched for relevant studies. Preclinical and clinical data were selected for inclusion based on novelty and pertinence to treatment of the obese patient.

FINDINGS

Recent guidelines suggest that all patients with type 2 diabetes should initially receive metformin as well as lifestyle intervention, followed by rapid administration of other oral anti-diabetic agents or insulin if glycemic goals are not met or maintained. Many oral anti-diabetic drugs, and insulin, are associated with weight gain. New agents with anti-diabetic activity that may be advantageous in obese patients with type 2 diabetes have recently become available. These include injectable incretin mimetics, which reduce blood glucose while reducing body weight but commonly cause nausea and vomiting. A new class of oral agents, the dipeptidyl peptidase-4 inhibitors, is weight-neutral and largely devoid of gastrointestinal side-effects. The cannabinoid receptor antagonist rimonabant is the first of a new class of anti-obesity agents that reduces central obesity and improves multiple aspects of vascular risk.

CONCLUSION

New agents offer the prospect of improved glycemic control without weight gain. However, the ultimate roles of these agents in the treatment of obese patients with type 2 diabetes remain to be established.

Cost effectiveness of duloxetine in the treatment of diabetic peripheral neuropathic pain in the UK

OBJECTIVE

The objective of this analysis was to evaluate the cost-effectiveness of duloxetine when considered as an additional treatment option for UK-based patients suffering from diabetic peripheral neuropathic pain.

RESEARCH DESIGN AND METHODS

A decision-analytic model was used to represent the sequential management of patients with diabetic peripheral neuropathic pain. The standard UK treatment strategy was defined as first-line tricyclic antidepressants (amitriptyline), second-line anticonvulsants (gabapentin) and lastly an opioid-related treatment. The cost-effectiveness of duloxetine was evaluated as an additional first, second, third or fourth-line therapy over a 6-month treatment period for a cohort of 1000 patients. Treatment response was modelled based on changes from baseline pain severity using a standard 11-point pain scale (0-10); full response (>or= 50% change), partial response (30-49%) and no response (< 30%). The model was populated with efficacy and discontinuation data using indirect comparisons of treatment efficacy based on relative effects to a common placebo comparator.

RESULTS

The second-line use of duloxetine resulted in cost savings of pound 77,071 for every 1000 treated patients, with an additional 29 patients achieving a full pain response when compared to standard UK treatment. Additional quality-adjusted life years (QALYs) were achieved at 1.88 QALYs per 1000 patients.

CONCLUSIONS

This UK-based economic model suggests that second-line use of duloxetine is a beneficial and cost-effective treatment strategy for diabetic peripheral neuropathic pain.