DPP-4 inhibitors in the management of type 2 diabetes: a critical review of head-to-head trials. Diabetes Metab. 2012;38:89-101. [PMID: 22197148 DOI: 10.1016/j.diabet.2011.11.001]

Head-to-head comparison of dipeptidyl peptidase-IV inhibitors and sulfonylureas - a meta-analysis from randomized clinical trials

BACKGROUND

Dipeptidyl peptidase-IV (DPP-4) inhibitors and sulfonylureas are two important second-line anti-diabetic agents. The objective of this research was to evaluate the efficacy and safety of DPP-4 inhibitors compared with sulfonylureas by meta-analytic approach of available randomized studies.

METHODS

We searched MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials databases up to 30 June 2013, collecting all randomized clinical trials with a treatment duration of ≥18weeks. Data on glycated haemoglobin (HbA1c ), body weight, hypoglycaemia, total adverse events, and cardiovascular events were retrieved and analysed.

RESULTS

The analysis included 12 randomized studies comprising 10 982 patients with type 2 diabetes mellitus. On the basis of meta-analysis, sulfonylureas lowered HbA1c significantly more than DPP-4 inhibitors with weighted mean difference (WMD) of 0.105 [95% confidence interval (CI) 0.103 to 0.107]. The results were consistent in trials with longer (>32 weeks) or shorter (≤32 weeks) duration; however, DPP-4 inhibitors showed greater reduction in HbA1c compared with the second-generation sulfonylureas and in patients with baseline eGFR < 50 mL/min/1.73 m(2) . Patients treated with DPP-4 inhibitors are less likely to achieve HbA1c  < 7% compared with sulfonylureas [Mantel-Haenszel odds ratio (MH-OR) 0.91; 95% CI 0.84 to 0.99]. DPP-4 xinhibitors were associated with a reduction in body weight (WMD -1.652; 95% CI -1.658 to -1.646) and lower risk of hypoglycaemia (MH-OR, 0.13; 95% CI 0.11 to 0.16), total adverse events (MH-OR, 0.79; 95% CI 0.72 to 0.87), and cardiovascular events (MH-OR, 0.53; 95% CI 0.32 to 0.87) compared with sulfonylureas.

CONCLUSION

Although DPP-4 inhibitors are less efficacious compared with sulfonylureas, they demonstrate a beneficial effect on body weight, episodes of hypoglycaemia, and total adverse events.

The role of glucagon-like peptide-1 impairment in obesity and potential therapeutic implications

The hormone glucagon-like peptide-1 (GLP-1) is released from the gut in response to food intake. It acts as a satiety signal, leading to reduced food intake, and also as a regulator of gastric emptying. Furthermore, GLP-1 functions as an incretin hormone, stimulating insulin release and inhibiting glucagon secretion from the pancreas in response to food ingestion. Evidence suggests that the action or effect of GLP-1 may be impaired in obese subjects, even in those with normal glucose tolerance. GLP-1 impairment may help explain the increased gastric emptying and decreased satiety signalling seen in obesity. Incretin impairment, probably associated with reduced insulinotropic potency of GLP-1, is also characteristic of type 2 diabetes (T2D). Therefore, it is possible that incretin impairment may contribute to the pathophysiological bridge between obesity and T2D. This review summarises current knowledge about the pathophysiology and consequences of GLP-1 and incretin impairment in obesity, and examines the evidence for an incretin-related link between obesity and T2D. It also considers the current literature surrounding the novel use of GLP-1 receptor agonists as a treatment for obesity in patients with normoglycaemia, prediabetes and T2D.

Efficacy of initial Basal-supported oral therapy with sitagliptin in untreated type 2 diabetes

INTRODUCTION

The present study assessed the efficacy of initial basal-supported oral therapy (BOT) with sitagliptin for achievement of glycemic control and subsequent switching from BOT to sitagliptin-based oral therapy.

METHODS

Nineteen recently diagnosed type 2 diabetic patients who had received no antidiabetic medication in the previous 2 years were sequentially examined for the 24-week study. Patients were initially treated with a combination of insulin glargine and sitagliptin. Sitagliptin was initiated and maintained at a dose of 50 mg/day, and insulin glargine was started at a dose of 4 U at bedtime and adjusted if needed.

RESULTS

During the 24-week treatment period, 12 patients (63%) achieved HbA1c levels <7% (mean BOT duration 13.7 ± 5.6 weeks) and switched from BOT to sitagliptin monotherapy or in combination with metformin (achievers). The remaining seven patients (37%) failed to achieve HbA1c levels <7% (non-achievers) and continued on BOT. Both FPG and HbA1c in achievers significantly dropped at 4, 8, 12 and 24 weeks from baseline, while those in non-achievers significantly decreased at 12 and 24 weeks from baseline, but failed to reach target glycemic control. There were statistically significant differences in FPG at 4, 8, 12 and 24 weeks and in HbA1c at 8, 12 and 24 weeks between achievers and non-achievers. Body weight and BMI in achievers were significantly reduced at 12 and 24 weeks, but those in non-achievers did not change significantly. Dosage of concomitant insulin during BOT was significantly lower in achievers compared to non-achievers. Non-achievers had a similar CPI, a measure of insulin secretion capacity, to achievers, but significantly showed an insulin resistance index (value of 20/[fasting CPR × FPG]), in comparison to achievers.

CONCLUSION

Initiating BOT with sitagliptin followed by sitagliptin-based oral therapy is a useful option in untreated and poorly controlled patients with type 2 diabetes.

The dipeptidyl peptidase (DPP)-4 inhibitors for type 2 diabetes mellitus in challenging patient groups

Treating hyperglycemia is a critical aspect of managing type 2 diabetes mellitus (T2DM), but can be especially challenging in patients from vulnerable groups such as those with chronic kidney disease, African Americans, and older people. The dipeptidyl peptidase (DPP)-4 inhibitors are relatively new oral antidiabetes drugs that have been incorporated into treatment algorithms over the past few years and have also been studied in these vulnerable patients. Clinical trials with DPP-4 inhibitors have now been reported for all these patient groups and have demonstrated significant improvements in measures of hyperglycemia, with a good safety profile. Based on the current evidence, it appears that the DPP-4 inhibitors are worthy of consideration not only for the most straightforward patients with T2DM, but also for these vulnerable patients.

Cardiovascular effects of dipeptidyl peptidase-4 inhibitors: from risk factors to clinical outcomes

Dipeptidyl peptidase-4 (DPP-4) inhibitors (gliptins) are oral incretin-based glucose-lowering agents with proven efficacy and safety in the management of type 2 diabetes mellitus (T2DM). In addition, preclinical data and mechanistic studies suggest a possible additional non-glycemic beneficial action on blood vessels and the heart, via both glucagon-like peptide-1-dependent and glucagon-like peptide-1-independent effects. As a matter of fact, DPP-4 inhibitors improve several cardiovascular risk factors: they improve glucose control (mainly by reducing the risk of postprandial hyperglycemia) and are weight neutral; may lower blood pressure somewhat; improve postprandial (and even fasting) lipemia; reduce inflammatory markers; diminish oxidative stress; improve endothelial function; and reduce platelet aggregation in patients with T2DM. In addition, positive effects on the myocardium have been described in patients with ischemic heart disease. Results of post hoc analyses of phase 2/3 controlled trials suggest a possible cardioprotective effect with a trend (sometimes significant) toward lower incidence of major cardiovascular events with sitagliptin, vildagliptin, saxagliptin, linagliptin, or alogliptin compared with placebo or other active glucose-lowering agents. However, the definite relationship between DPP-4 inhibition and better cardiovascular outcomes remains to be proven. Major prospective clinical trials involving various DPP-4 inhibitors with predefined cardiovascular outcomes are under way in patients with T2DM and a high-risk cardiovascular profile: the Sitagliptin Cardiovascular Outcome Study (TECOS) on sitagliptin, the Saxagliptin Assessment of Vascular Outcomes Recorded in Patients With Diabetes Mellitus-Thrombolysis in Myocardial Infarction (SAVOR-TIMI) 53 trial on saxagliptin, the Cardiovascular Outcomes Study of Alogliptin in Subjects With Type 2 Diabetes and Acute Coronary Syndrome (EXAMINE) trial on alogliptin, and the Cardiovascular Outcome Study of Linagliptin Versus Glimepiride in Patients With Type 2 Diabetes (CAROLINA) on linagliptin. If these trials confirm that a DPP-4 inhibitor can reduce the cardiovascular burden of T2DM, it would be major progress that would dramatically influence the management of the disease.

One-year real-life efficacy of sitagliptin revealed importance of concomitant pioglitazone use in Japanese patients with type 2 diabetes mellitus

AIMS

Dipeptidyl-peptidase 4 inhibitors have become one of the most popular antidiabetic drugs. However, what kind of combinations with other drugs were advantageous was not known. Here, we tried to elucidate it in a real-life clinical setting.

METHODS

We retrospectively studied efficacies of sitagliptin in 87 Japanese patients with type 2 diabetes mellitus for 52 weeks. We divided subjects into excellent, effective and unresponsive subgroups according to glycemic responses to sitagliptin.

RESULTS

In the excellent and effective groups the minimum HbA1c values were attained at 16 weeks while HbA1c levels in the unresponsive group kept increasing during the study period. There was a significant difference in the baseline HbA1c values between the excellent and unresponsive groups (p=0.02). Interestingly, the mean doses of pioglitazone were highest in the excellent group and lowest in the unresponsive group (p=0.02). When we compared the effective and unresponsive groups, the mean doses of sulfonylureas were constantly higher in the effective group than in the unresponsive group (p=0.05).

CONCLUSIONS

These data suggest that the baseline HbA1c value can be a factor that predicts the extent of HbA1c reduction and reveal a possibility that the concomitant use of pioglitazone augments glycemic responsiveness to sitagliptin.

Vildagliptin in the Treatment of Type 2 Diabetes Mellitus

Novel therapeutic approaches are continuously being researched in type 2 diabetes. The incretin class of anti-diabetic agents, consisting of glucagon-like peptide-1 agonists and dipeptidyl peptidase-4 inhibitors, has already found an important place in the current guidelines. Vildagliptin is a potent dipeptidyl peptidase-4 inhibitor, with numerous trials in type 2 diabetes treatment, both in monotherapy and in combination therapy. This review focuses on vildagliptin pharmacological properties, clinical efficacy and safety, and pharmacoeconomic data.

Teneligliptin: a DPP-4 inhibitor for the treatment of type 2 diabetes

Dipeptidyl peptidase-4 (DPP-4) inhibitors have recently emerged as a new class of antidiabetic that show favorable results in improving glycemic control with a minimal risk of hypoglycemia and weight gain. Teneligliptin, a novel DPP-4 inhibitor, exhibits a unique structure characterized by five consecutive rings, which produce a potent and long-lasting effect. Teneligliptin is currently used in cases showing insufficient improvement in glycemic control even after diet control and exercise or a combination of diet control, exercise, and sulfonylurea- or thiazolidine-class drugs. In adults, teneligliptin is orally administered at a dosage of 20 mg once daily, which can be increased up to 40 mg per day. Because the metabolites of this drug are eliminated via renal and hepatic excretion, no dose adjustment is necessary in patients with renal impairment. The safety profile of teneligliptin is similar to those of other available DPP-4 inhibitors. However, caution needs to be exercised when administering teneligliptin to patients who are prone to QT prolongation. One study has reported that the postprandial blood glucose-lowering effects of teneligliptin administered prior to breakfast were sustained throughout the day, and the effects observed after dinner were similar to those observed after breakfast or lunch. Thus, although clinical data for this new drug are limited, this drug shows promise in stabilizing glycemic fluctuations throughout the day and consequently suppressing the progression of diabetic complications. However, continued evaluation in long-term studies and clinical trials is required to evaluate the efficacy and safety of the drug as well as to identify additional indications for its clinical use.

Gliptins (dipeptidyl peptidase-4 inhibitors) and risk of acute pancreatitis

INTRODUCTION

Dipeptidyl peptidase-4 (DPP-4) inhibitors (gliptins) play an increasing role in the management of type 2 diabetes. Such incretin-based therapies offer some advantages over other glucose-lowering agents, but might be associated with an increased risk of acute pancreatitis.

AREAS COVERED

An extensive literature search was performed to analyze clinical cases of acute pancreatitis reported in the literature or to the Food and Drug Administration (FDA), in randomized clinical trials, and in observational studies with five DPP-4 inhibitors: sitagliptin, vildagliptin, saxagliptin, alogliptin, and linagliptin.

EXPERT OPINION

An increased risk of pancreatitis has been reported in diabetic versus nondiabetic patients. Several anecdotal clinical cases of pancreatitis have been reported with sitagliptin and vildagliptin and an increased relative risk reported to the FDA with sitagliptin versus other comparators, but reporting bias cannot be excluded. In rather short-term clinical trials with well-selected diabetic patients, no increased risk of acute pancreatitis has been observed with any of the five commercialized DPP-4 inhibitors: sitagliptin, vildagliptin, saxagliptin, alogliptin, and linagliptin. Similarly, real-life cohort studies showed no increased incidence of pancreatitis with gliptins compared with other glucose-lowering agents, a finding recently challenged by a case- control study. These results must be confirmed in postmarketing surveillance programs and in ongoing large prospective trials with cardiovascular outcomes.

GLP-1 receptor agonists or DPP-4 inhibitors: how to guide the clinician?

Pharmacological treatment of type 2 diabetes has been enriched during recent years, with the launch of incretin therapies targeting glucagon-like peptide-1 (GLP-1). Such medications comprise either GLP-1 receptor agonists, with short (one or two daily injections: exenatide, liraglutide, lixisenatide) or long duration (one injection once weekly: extended-released exenatide, albiglutide, dulaglutide, taspoglutide); or oral compounds inhibiting dipeptidyl peptidase-4 (DPP-4), the enzyme that inactives GLP-1, also called gliptins (sitagliptin, vildagliptin, saxagliptin, linagliptin, alogliptin). Although both pharmacological approaches target GLP-1, important differences exist concerning the mode of administration (subcutaneous injection versus oral ingestion), the efficacy (better with GLP-1 agonists), the effects on body weight and systolic blood pressure (diminution with agonists versus neutrality with gliptins), the tolerance profile (nausea and possibly vomiting with agonists) and the cost (higher with GLP-1 receptor agonists). Both agents may exert favourable cardiovascular effects. Gliptins may represent a valuable alternative to a sulfonylurea or a glitazone after failure of monotherapy with metformin while GLP-1 receptor agonists may be considered as a good alternative to insulin (especially in obese patients) after failure of a dual oral therapy. However, this scheme is probably too restrictive and modalities of using incretins are numerous, in almost all stages of type 2 diabetes. Physicians may guide the pharmacological choice based on clinical characteristics, therapeutic goals and patient's preference.

Combine and conquer: advantages and disadvantages of fixed-dose combination therapy

The majority of patients with type 2 diabetes mellitus (T2DM) do not achieve the glycaemic goals recommended by leading diabetes organizations using monotherapy alone, and often require multiple antihyperglycaemic agents to achieve glycaemic control. Fixed-dose combination (FDC) therapies offer a means to simplify complex treatment regimens, and have several advantages that help patients reach their glycaemic goals. In this review, four key benefits are identified and discussed in support of FDCs for treatment of patients with T2DM: (i) Greater efficacy compared with higher dose monotherapy, (ii) Reduced risk of adverse reactions relative to higher dose monotherapy, (iii) Lower overall costs and (iv) Improved medication concordance. Given these advantages, the place of fixed combination therapy in the course of treatment is discussed. Establishing a therapeutic strategy that incorporates fixed combination therapy (including combinations with insulin) will simplify the treatment of diabetes, ideally resulting in improved medication concordance, clinical outcomes and quality of life for patients with T2DM.

Long-term safety of linagliptin monotherapy in Japanese patients with type 2 diabetes

AIMS

In a phase III study conducted among Japanese patients with type 2 diabetes mellitus (T2DM), linagliptin 5 and 10 mg showed clinically meaningful improvements in glycaemic parameters after 12 and 26 weeks compared with placebo and voglibose, respectively. This extension study assessed long-term tolerability of linagliptin over 52 weeks.

METHODS

Japanese patients with T2DM who completed either phase of a 12-week/26-week study comparing linagliptin monotherapy with placebo or voglibose were eligible to enrol. In the extension study, the comparator groups switched to linagliptin 5 or 10 mg, while the linagliptin groups maintained dosage.

RESULTS

In all, 540 patients received at least one dose of linagliptin 5 or 10 mg and 494 completed the extension. Long-term treatment with linagliptin was well tolerated; adverse events (AEs) of special interest and serious AEs occurred in small percentages of patients. Drug-related AEs occurred in 10.2 and 10.6% of patients in the linagliptin 5- and 10-mg groups, respectively, and discontinuations due to drug-related AEs occurred in 1.1 and 0.7%, respectively. Only one (0.4%) patient in each dose group experienced investigator-defined hypoglycaemia during the treatment period (both events were non-severe). Body weight was not clinically altered in either group. The glycated haemoglobin A1c profiles over time were similar with linagliptin 5 and 10 mg.

CONCLUSIONS

These findings provide evidence for the safety and tolerability of oral linagliptin at either 5 or 10 mg for up to 52 weeks for the treatment of Japanese patients with T2DM, without clinically relevant increase in the risk of hypoglycaemia or weight gain.

Glucagon-like peptide-1 and its cardiovascular effects

Recently, the crucial role of GLP-1 in cardiovascular disease has been suggested by both preclinical and clinical studies. In vivo and in vitro studies have demonstrated cardio-protective effects of GLP-1 by activating cell survival signal pathways, which have greatly reduced ischemia/reperfusion injury and also cardiac dysfunction in various congestive heart failure animal models. Clinically, beneficial effects of GLP-1 have been shown in patients with myocardial infarction, hypertension, and heart failure, and 2 classes of incretin enhancers, GLP-1 receptor agonists and DPP-4 inhibitors, are currently available for the treatment of type 2 diabetes mellitus. In this review, we will summarize the role of incretins in various cardiovascular events such as hypertension and heart failure and postprandial lipoprotein secretion, and discuss their molecular mechanisms and potentials as a new therapeutic as well as preventive drug type for reducing cardiovascular events in both diabetic and nondiabetic patients.

Metformin revisited: a critical review of the benefit-risk balance in at-risk patients with type 2 diabetes

Metformin is unanimously considered a first-line glucose-lowering agent. Theoretically, however, it cannot be prescribed in a large proportion of patients with type 2 diabetes because of numerous contraindications that could lead to an increased risk of lactic acidosis. Various observational data from real-life have shown that many diabetic patients considered to be at risk still receive metformin and often without appropriate dose adjustment, yet apparently with no harm done and particularly no increased risk of lactic acidosis. More interestingly, recent data have suggested that type 2 diabetes patients considered at risk because of the presence of traditional contraindications may still derive benefit from metformin therapy with reductions in morbidity and mortality compared with other glucose-lowering agents, especially sulphonylureas. The present review analyzes the benefit-risk balance of metformin therapy in special populations, namely, patients with stable coronary artery disease, acute coronary syndrome or myocardial infarction, congestive heart failure, renal impairment or chronic kidney disease, hepatic dysfunction and chronic respiratory insufficiency, all conditions that could in theory increase the risk of lactic acidosis. Special attention is also paid to elderly patients with type 2 diabetes, a population that is growing rapidly, as older patients can accumulate several comorbidities classically considered contraindications to the use of metformin. A review of the recent scientific literature suggests that reassessment of the contraindications of metformin is now urgently needed to prevent physicians from prescribing the most popular glucose-lowering therapy in everyday clinical practice outside of the official recommendations.

An emerging role of dipeptidyl peptidase 4 (DPP4) beyond glucose control: potential implications in cardiovascular disease

The introduction of dipeptidyl peptidase 4 (DPP4) inhibitors for the treatment of Type 2 diabetes acknowledges the fundamental importance of incretin hormones in the regulation of glycemia. Small molecule inhibitors of DPP4 exert their effects via inhibition of enzymatic degradation of glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP). The widespread expression of DPP4 in tissues such as the vasculature and immune cells suggests that this protein may play a role in cardiovascular function. DPP4 is known to exert its effects via both enzymatic and non-enzymatic mechanisms. A soluble form of DPP4 lacking the cytoplasmic and transmembrane domain has also been recently recognized. Besides enzymatic inactivation of incretins, DPP4 also mediates degradation of many chemokines and neuropeptides. The non-enzymatic function of DPP4 plays a critical role in providing co-stimulatory signals to T cells via adenosine deaminase (ADA). DPP4 may also regulate inflammatory responses in innate immune cells such as monocytes and dendritic cells. The multiplicity of functions and targets suggests that DPP4 may play a distinct role aside from its effects on the incretin axis. Indeed recent studies in experimental models of atherosclerosis provide evidence for a robust effect for these drugs in attenuating inflammation and plaque development. Several prospective randomized controlled clinical trials in humans with established atherosclerosis are testing the effects of DPP4 inhibition on hard cardiovascular events.

Cardiovascular effects of gliptins

Dipeptidyl peptidase 4 (DPP-4) inhibitors (commonly referred to as gliptins) are a novel class of oral antihyperglycaemic agents with demonstrated efficacy in the treatment of type 2 diabetes mellitus (T2DM). Preclinical data and mechanistic studies have indicated a possible beneficial action on blood vessels and the heart, via both glucagon-like peptide 1 (GLP-1)-dependent and GLP-1-independent effects. DPP-4 inhibition increases the concentration of many peptides with potential vasoactive and cardioprotective effects. Clinically, DPP-4 inhibitors improve several risk factors in patients with T2DM. They improve blood glucose control (mainly by reducing postprandial glycaemia), are weight neutral (or even induce modest weight loss), lower blood pressure, improve postprandial lipaemia, reduce inflammatory markers, diminish oxidative stress, and improve endothelial function. Some positive effects on the heart have also been described in patients with ischaemic heart disease or congestive heart failure, although their clinical relevance requires further investigation. Post-hoc analyses of phase II-III, controlled trials suggest a possible cardioprotective effect with a trend for a lower incidence of major cardiovascular events with gliptins than with placebo or active agents. However, the actual relationship between DPP-4 inhibition and cardiovascular outcomes remains to be proven. Major prospective clinical trials with predefined cardiovascular outcomes and involving various DPP-4 inhibitors are now underway in patients with T2DM and a high-risk cardiovascular profile.