Saxagliptin for the treatment of type 2 diabetes mellitus: assessing cardiovascular data

Unveiling Diabetes: Categories, Genetics, Diagnostics, Treatments, and Future Horizons

Diabetes mellitus is a global epidemic affecting millions of individuals worldwide. This comprehensive review aims to provide a thorough understanding of the categorization, disease identity, genetic architecture, diagnosis, and treatment of diabetes. The categorization of diabetes is discussed, with a focus on type 1 and type 2 diabetes, as well as the lesser-known types, type 3 and type 4 diabetes. The geographical variation, age, gender, and ethnic differences in the prevalence of type 1 and type 2 diabetes are explored. The impact of disease identity on disease management and the role of autoimmunity in diabetes are examined. The genetic architecture of diabetes, including the interplay between genotype and phenotype, is discussed to enhance our understanding of the underlying mechanisms. The importance of insulin injection sites and the insulin signalling pathway in diabetes management are highlighted. The diagnostic techniques for diabetes are reviewed, along with advancements for improved differentiation between types. Treatment and management approaches, including medications used in diabetes management are presented. Finally, future perspectives are discussed, emphasizing the need for further research and interventions to address the global burden of diabetes. This review serves as a valuable resource for healthcare professionals, researchers, and policymakers, providing insights to develop targeted strategies for the prevention, diagnosis, and management of this complex disease.

Plasma-Soluble Dipeptidyl Peptidase 4 and Risk of Major Cardiovascular Events After Ischemic Stroke: Secondary Analysis of China Antihypertensive Trial in Acute Ischemic Stroke (CATIS)

BACKGROUND AND OBJECTIVES

Recent studies have suggested that plasma soluble dipeptidyl peptidase-4 (sDPP4) have important physiological effects, which may influence the prognosis of ischemic stroke. Our study aimed to examine the relationship between plasma sDDP4 levels and long-term clinical outcomes among acute ischemic stroke patients.

METHODS

Secondary analysis was conducted among 3,564 participants (2,270 men and 1,294 women) from the China Antihypertensive Trial in Acute Ischemic Stroke with baseline measurement of plasma sDPP4 levels. We evaluated the associations between plasma sDPP4 levels and 2-year clinical outcomes using logistic regression and Cox regression models. We further investigated the predictive utility of sDPP4 by calculating net reclassification index (NRI) and integrated discrimination improvement (IDI).

RESULTS

The highest plasma sDPP4 quartile was associated with lower risk of cardiovascular events (HR 0.62, 95% CI 0.45-0.87), recurrent stroke (HR 0.70, 95% CI 0.49-0.99), all-cause mortality (HR 0.62, 95% CI 0.44-0.87), stroke-specific mortality (HR 0.65, 95% CI 0.44-0.94) and poor functional outcomes (OR 0.66, 95% CI 0.53-0.82) at 2 years compared with the lowest sDPP4 category in multivariable models. The addition of plasma sDPP4 to conventional risk factors model significantly improved risk prediction of all outcomes.

DISCUSSION

In this study, we found that higher plasma sDPP4 levels in acute ischemic stroke patients were associated with decreased risks of cardiovascular events, recurrent stroke, all-cause mortality, and poor functional outcomes after ischemic stroke. These findings suggest that plasma sDPP4 may be a potential prognostic marker for initial risk stratification in patients with acute ischemic stroke.

Blood Pressure-Lowering Effect of Newer Antihyperglycemic Agents (SGLT-2 Inhibitors, GLP-1 Receptor Agonists, and DPP-4 Inhibitors)

The prevalence of arterial hypertension is high in patients with diabetes mellitus (DM). When DM and hypertension coexist, they constitute a dual cardiovascular threat and should be adequately controlled. Novel antihyperglycemic agents, including sodium-glucose co-transporter 2 (SGLT-2) inhibitors, glucagon-like peptide-1 receptor agonists (GLP-1 RAs), and dipeptidyl peptidase-4 (DPP-4) inhibitors, have recently been used in the treatment of DM. Beyond their glucose-lowering effects, these drugs have shown beneficial pleiotropic cardiovascular effects, including lowering of arterial blood pressure (BP), as acknowledged in the 2019 European Society of Cardiology/European Association for the Study of Diabetes guidelines on diabetes, prediabetes, and cardiovascular diseases. The purpose of this review was to summarize the available information on the BP-reducing effects of these new glucose-lowering drug classes and provide a brief report on underlying pathophysiological mechanisms. We also compare the three drug classes (SGLT-2 inhibitors, GLP-1 RAs, and DPP-4 inhibitors) in terms of their BP-lowering effect and show that the greater BP reduction seems to be achieved with SGLT-2 inhibitors, whereas DPP-4 inhibitors have probably the mildest antihypertensive effect.

Saxagliptin and vildagliptin lowered albuminuria in patients with diabetes and hypertension independent on glycaemic control

BACKGROUND

Preclinical data illustrated that the dipeptidyl peptidase-4(DPP-4) inhibitors did lower urinary albumin excretion in diabetes-induced rats. We evaluated the effects of saxagliptin and vildagliptin on albuminuria in patients with diabetic nephropathy on top of the renin-angiotensin-aldosterone system (RAAS) blockade therapy.

METHODS

This study included 120 patients with type 2 diabetes (T2D), hypertension, and prevalent albuminuria [defined as urine albumin-to-creatinine ratio (UACR) 30-3000mg/g creatinine] on a stable dose of olmesartan as a standard RAAS blocker for diabetic nephropathy. Patients were assigned to receive either of saxagliptin 5mg/day (n = 40), vildagliptin 100mg/day (n = 40), or traditional antidiabetic therapy as control patients (n = 40) for 12 weeks.

RESULTS

Each of saxagliptin and vildagliptin significantly reduced albuminuria after 12 weeks, with mean percentage changes (%) of -57.9% [95% confidence interval (CI) -66.1 to -49.8], and -55.2% (95% CI -64.9 to -45.4); P < .001, respectively, compared with the control group. Significantly, saxagliptin shifted higher proportions of patients towards lower albuminuria categories (P < .001) compared with vildagliptin despite a similar UACR rate of changes. Results of binary logistic models confirmed that the change in UACR because saxagliptin was independent of changes in systolic blood pressure (SBP), glycated hemoglobin (HbA_1c ), estimated glomerular filtration rate (eGFR), or body weight (overall regression: P = .002, R²  = 0.398) vs control. Likewise, vildagliptin reduced UACR independently on other confounders (overall regression: P = .002, R²  = 0.388). Furthermore, no significant correlation was observed between the change in UACR and changes in HbA1c, SBP or eGFR with either saxagliptin or vildagliptin (Pearson coefficients: 0.203, 0.143, -0.190; P > .05, and 0.003, 0.241, 0.019; P > .05, respectively).

CONCLUSIONS

DPP-4 inhibitors, saxagliptin, and vildagliptin, resulted in substantial reductions in albuminuria in patients with T2D and hypertension on top of RAAS blockade after short term therapy independently on glycaemic or hemodynamic changes. Saxagliptin was superior to vildagliptin in albuminuria-categorical shifting.

Pharmacological treatment of hyperglycemia in type 2 diabetes

Diabetes mellitus is a major public health problem, affecting about 10% of the population. Pharmacotherapy aims to protect against microvascular complications, including blindness, end-stage kidney disease, and amputations. Landmark clinical trials have demonstrated that intensive glycemic control slows progression of microvascular complications (retinopathy, nephropathy, and neuropathy). Long-term follow-up has demonstrated that intensive glycemic control also decreases risk of macrovascular disease, albeit rigorous evidence of macrovascular benefit did not emerge for over a decade. The US FDA's recent requirement for dedicated cardiovascular outcome trials ushered in a golden age for understanding the clinical profiles of new type 2 diabetes drugs. Some clinical trials with sodium-glucose cotransporter-2 (SGLT2) inhibitors and glucagon-like peptide 1 (GLP1) receptor agonists reported data demonstrating cardiovascular benefit (decreased risk of major adverse cardiovascular events and hospitalization for heart failure) and slower progression of diabetic kidney disease. This Review discusses current guidelines for use of the 12 classes of drugs approved to promote glycemic control in patients with type 2 diabetes. The Review also anticipates future developments with potential to improve the standard of care: availability of generic dipeptidylpeptidase-4 (DPP4) inhibitors and SGLT2 inhibitors; precision medicine to identify the best drugs for individual patients; and new therapies to protect against chronic complications of diabetes.

Saxagliptin protects against hypoxia-induced damage in H9c2 cells

Type II diabetes is recognized as a major risk factor for death due to cardiovascular complications such as coronary heart disease (CHD), but the complex interplay between these two diseases remains poorly understood. Suppression of oxidative stress, apoptosis, and inflammation of endothelial cells is a valuable treatment strategy to prevent or halt the progression of CHD. In the present study, we used real-time polymerase chain reaction (PCR), Western blot analysis, and enzyme linked immunosorbent assay (ELISA) to investigate the effects of saxagliptin on hypoxia-inducible factors. Our findings demonstrate that saxagliptin can significantly improve cell viability in H9c2 cells as well as reduce hypoxia-induced oxidative damage and loss of mitochondrial membrane potential. Saxagliptin reduced hypoxia-induced NADPH oxidase 4 (NOX 4). We also show that saxagliptin can reduce the expression of matrix metallopeptidase-2 (MMP-2) and matrix metallopeptidase-9 (MMP-9), two important degradative enzymes. Saxagliptin also suppressed hypoxia-induced expression of high mobility group box-1 protein (HMGB1), a key inflammatory cytokine. Finally, we show that saxagliptin can exert atheroprotective effects by reducing the expression of myeloid differential protein-88 (MyD88) and increasing the expression of nuclear factor erythroid-2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1). Thus, saxagliptin shows promise as a treatment against diabetes-associated CHD.

Glucagon-Like Peptide-1 Receptor Agonists and Strategies To Improve Their Efficiency

Type 2 diabetes mellitus (T2DM) is increasing in global prevalence and is associated with serious health problems (e.g., cardiovascular disease). Various treatment options are available for T2DM, including the incretin hormone glucagon-like peptide-1 (GLP-1). GLP-1 is a therapeutic peptide secreted from the intestines following food intake, which stimulates the secretion of insulin from the pancreas. The native GLP-1 has a very short plasma half-life, owning to renal clearance and degradation by the enzyme dipeptidyl peptidase-4. To overcome this issue, various GLP-1 agonists with increased resistance to proteolytic degradation and reduced renal clearance have been developed, with several currently marketed. Strategies, such as controlled release delivery systems, methods to reduce renal clearance (e.g., PEGylation and conjugation to antibodies), and methods to improve proteolytic stability (e.g., stapling, cyclization, and glycosylation) provide means to further improve the ability of GLP-1 analogs. These will be discussed in this literature review.

Renoprotection Provided by Dipeptidyl Peptidase-4 Inhibitors in Combination with Angiotensin Receptor Blockers in Patients with Type 2 Diabetic Nephropathy

Background:

Treatment with the dipeptidyl peptidase-4 inhibitors (DPP4i) and angiotensin receptor blockers (ARBs) in patients with type 2 diabetic nephropathy (DN) has not been well characterized. This study aimed to assess the renoprotection of this combined treatment in DN patients.

Methods:

A total of 159 type 2 DN patients from 2013 to 2015 were enrolled retrospectively from a prospective DN cohort at the National Clinical Research Center of Kidney Diseases, Jinling Hospital (China). Fifty-seven patients received DPP4i and ARB treatment, and 102 patients were treated with ARBs alone. All patients were followed up for at least 12 months. Statistical analyses were performed using Stata version 12.0.

Results:

There were no significant differences at baseline for age, sex, body mass index, duration of diabetes, fasting blood glucose (FBG), hemoglobin A1c (HbA1c), and estimated glomerular filtration rate (eGFR) between the two groups. Antihypertensive and antidiabetic medication use was similar in each group except calcium channel antagonists (P = 0.032). No significant changes in FBG and HbA1c were observed in the two groups after treatment. The eGFR decreased slower in the DPP4i + ARB group than in the ARB group at 12 months (Δ12 months: −2.48 ± 13.86 vs. −6.81 ± 12.52 ml·min^–1·1.73m^–2, P = 0.044). In addition, proteinuria was decreased further in the DPP4i + ARB group than in the ARB group after 24 months of treatment (Δ24 months: −0.18 [−1.00, 0.17] vs. 0.32 [−0.35, 0.88], P = 0.031). There were 36 patients with an eGFR decrease of more than 30% over 24 months. After adjusting for FBG, HbA1c, and other risk factors, DPP4i + ARB treatment was still associated with a reduced incidence of an eGFR decrease of 20% or 30%.

Conclusions:

The combined treatment of DPP4i and ARBs is superior to ARBs alone, as evidenced by the greater proteinuria reduction and lower eGFR decline. In addition, the renoprotection of DPP4i combined with ARBs was independent of glycemic control.

Differences in All-Cause Health Care Utilization and Costs in a Type 2 Diabetes Mellitus Population with and Without a History of Cardiovascular Disease

BACKGROUND

Multiple studies have reported that type 2 diabetes mellitus (T2DM) is a major risk factor for cardiovascular diseases (CVD), and presence of T2DM and CVD increases risk of death. There is growing interest in examining the effects of antidiabetic treatments on the reduction of cardiovascular events in T2DM adults with a history of CVD and thus at higher risk of cardiovascular events.

OBJECTIVE

To estimate the incremental all-cause health care utilization and costs among adults with T2DM and a history of CVD compared with adults without a history of CVD, using a national linked electronic medical records (EMR) and claims database.

METHODS

Adults aged ≥ 18 years with evidence of at least 1 T2DM-related diagnosis code or antidiabetic medication (date of earliest occurrence was defined as the index date) in calendar year 2012 were identified. The population was divided into 2 cohorts (with and without a history of CVD) and followed until the end of their enrollment coverage, death, or 12 months, whichever came first. Multivariable generalized linear models were used to assess differences in health care utilization and per patient per month (PPPM) total costs (plan- and patient-paid amount for health care services) between the 2 groups during the post-index year, while adjusting for an a priori list of demographic and clinical characteristics.

RESULTS

A total of 138,018 adults with T2DM was identified, of which 16,547 (12%) had a history of CVD. The unadjusted resource utilization (outpatient: 27.5 vs. 17.8; emergency room [ER]: 0.8 vs. 0.4; inpatient: 0.4 vs. 0.2 days; and total unique drug prescriptions: 10.1 vs. 8.3) and PPPM total health care costs ($2,655.1 vs. $1,435.0) were significantly higher in T2DM adults with a history of CVD versus T2DM adults without a history of CVD. The adjusted models revealed that T2DM adults with a history of CVD had a 31% higher number of ER visits (rate ratio [RR] = 1.31, 95% CI = 1.25-1.37); 27% more inpatient visits (RR = 1.27, 95% CI = 1.21-1.34); 15% longer mean inpatient length of stay (RR = 1.15, 95% CI = 1.06-1.25); and 11% more outpatient visits (RR = 1.11, 95% CI = 1.09-1.13) compared with T2DM adults without a history of CVD. Furthermore, the difference in total PPPM health care cost was found to be 16% ($200) higher in adults with a history of CVD (RR = 1.16, 95% CI = 1.13-1.19). PPPM costs associated with outpatient and ER visits were approximately 21% and 19% higher among adults with a history of CVD, respectively (P < 0.0001), while costs for inpatient visits were similar between the 2 groups. In addition, a subgroup analysis revealed that adjusted differences in PPPM total cost was larger in the younger age group (56% higher cost in those aged < 45 years) and diminished in the older age group (only 2% higher in those aged ≥ 65 years).

CONCLUSIONS

Study findings showed that resource utilization and costs remains significantly higher in T2DM patients with a history of CVD compared with patients without a history of CVD even after controlling for significant patient comorbid and demographic characteristics. Also, younger age groups had higher differences in outcomes compared with older age groups. This study underscores the importance of cost-effective interventions that may reduce economic burden in this T2DM population with a history of CVD.

DISCLOSURES

This study was funded by Boehringer Ingelheim. At the time of this study, Mehta and Mountford were employed by IQVIA, which received funding from Boehringer Ingelheim to conduct this study. Mountford is employed by Allergan, which has no connection with this study. Ghosh, Sander, and Kuti are employed by Boehringer Ingelheim. Study concept and design were contributed by Mountford, Mehta, and Ghosh, along with Sander and Kuti. Mountford and Mehta collected the data, and data interpretation was performed by all the authors. The manuscript was written by Sander and Kuti, along with the other authors, and revised by Mehta and Gosh, along with the other authors.

The role of dipeptidylpeptidase-4 inhibitors in management of cardiovascular disease in diabetes; focus on linagliptin

Multiple population based analyses have demonstrated a high incidence of cardiovascular disease (CVD) and cardiovascular (CV) mortality in subjects with T2DM that reduces life expectancy by as much as 15 years. Importantly, the CV system is particularly sensitive to the metabolic and immune derangements present in obese pre-diabetic and diabetic individuals; consequently, CV dysfunction is often the initial CV derangement to occur and promotes the progression to end organ/tissue damage in T2DM. Specifically, diabetic CVD can manifest as microvascular complications, such as nephropathy, retinopathy, and neuropathy, as well as, macrovascular impairments, including ischemic heart disease, peripheral vascular disease, and cerebrovascular disease. Despite some progress in prevention and treatment of CVD, mainly via blood pressure and dyslipidemia control strategies, the impact of metabolic disease on CV outcomes is still a major challenge and persists in proportion to the epidemics of obesity and diabetes. There is abundant pre-clinical and clinical evidence implicating the DPP-4-incretin axis in CVD. In this regard, linagliptin is a unique DPP-4 inhibitor with both CV and renal safety profiles. Moreover, it exerts beneficial CV effects beyond glycemic control and beyond class effects. Linagliptin is protective for both macrovascular and microvascular complications of diabetes in preclinical models, as well as clinical models. Given the role of endothelial-immune cell interactions as one of the key events in the initiation and progression of CVD, linagliptin modulates these cell–cell interactions by affecting two important pathways involving stimulation of NO signaling and potent inhibition of a key immunoregulatory molecule.

Comparative Cardiovascular Risks of Dipeptidyl Peptidase-4 Inhibitors: Analyses of Real-world Data in Korea

Background and Objectives

To compare cardiovascular disease (CVD) risk associated with 5 different dipeptidyl peptidase-4 inhibitors (DPP-4is) in people with type 2 diabetes.

Methods

We identified 534,327 people who were newly prescribed sitagliptin (n=167,157), vildagliptin (n=67,412), saxagliptin (n=29,479), linagliptin (n=220,672), or gemigliptin (n=49,607) between January 2013 and June 2015 using the claims database of the Korean National Health Insurance System. A Cox proportional hazards model was used to estimate hazard ratios (HRs) for major CVD events (myocardial infarction, stroke, or death) among users of different DPP-4is. The model was adjusted for sex, age, duration of DPP-4i use, use of other glucose-lowering drugs, use of antiplatelet agents, hypertension, dyslipidemia, atrial fibrillation, chronic kidney disease, microvascular complications of diabetes, Charlson comorbidity index, and the calendar index year as potential confounders.

Results

Compared to sitagliptin users, the fully adjusted HRs for CVD events were 0.97 (95% confidence interval [CI], 0.94–1.01; p=0.163) for vildagliptin, 0.76 (95% CI, 0.71–0.81; p<0.001) for saxagliptin, 0.95 (95% CI, 0.92–0.98; p<0.001) for linagliptin, and 0.84 (95% CI, 0.80–0.88; p<0.001) for gemigliptin.

Conclusions

Compared to sitagliptin therapy, saxagliptin, linagliptin, and gemigliptin therapies were all associated with a lower risk of cardiovascular events.

Inhibiting DPP4 in a mouse model of HHT1 results in a shift towards regenerative macrophages and reduces fibrosis after myocardial infarction

AIMS

Hereditary Hemorrhagic Telangiectasia type-1 (HHT1) is a genetic vascular disorder caused by haploinsufficiency of the TGFβ co-receptor endoglin. Dysfunctional homing of HHT1 mononuclear cells (MNCs) towards the infarcted myocardium hampers cardiac recovery. HHT1-MNCs have elevated expression of dipeptidyl peptidase-4 (DPP4/CD26), which inhibits recruitment of CXCR4-expressing MNCs by inactivation of stromal cell-derived factor 1 (SDF1). We hypothesize that inhibiting DPP4 will restore homing of HHT1-MNCs to the infarcted heart and improve cardiac recovery.

METHODS AND RESULTS

After inducing myocardial infarction (MI), wild type (WT) and endoglin heterozygous (Eng+/-) mice were treated for 5 days with the DPP4 inhibitor Diprotin A (DipA). DipA increased the number of CXCR4+ MNCs residing in the infarcted Eng+/- hearts (Eng+/- 73.17±12.67 vs. Eng+/- treated 157.00±11.61, P = 0.0003) and significantly reduced infarct size (Eng+/- 46.60±9.33% vs. Eng+/- treated 27.02±3.04%, P = 0.03). Echocardiography demonstrated that DipA treatment slightly deteriorated heart function in Eng+/- mice. An increased number of capillaries (Eng+/- 61.63±1.43 vs. Eng+/- treated 74.30±1.74, P = 0.001) were detected in the infarct border zone whereas the number of arteries was reduced (Eng+/- 11.88±0.63 vs. Eng+/- treated 6.38±0.97, P = 0.003). Interestingly, while less M2 regenerative macrophages were present in Eng+/- hearts prior to DipA treatment, (WT 29.88±1.52% vs. Eng+/- 12.34±1.64%, P<0.0001), DPP4 inhibition restored the number of M2 macrophages to wild type levels.

CONCLUSIONS

In this study, we demonstrate that systemic DPP4 inhibition restores the impaired MNC homing in Eng+/- animals post-MI, and enhances cardiac repair, which might be explained by restoring the balance between the inflammatory and regenerative macrophages present in the heart.

Efficacy and safety of saxagliptin compared with acarbose in Chinese patients with type 2 diabetes mellitus uncontrolled on metformin monotherapy: Results of a Phase IV open-label randomized controlled study (the SMART study)

AIM

To investigate the efficacy, safety and tolerability of saxagliptin compared with acarbose in Chinese patients with type 2 diabetes mellitus inadequately controlled with metformin monotherapy.

METHODS

SMART was a 24-week, multicentre, randomized, parallel-group, open-label Phase IV study conducted at 35 sites in China (September 24, 2014 to September 29, 2015). The primary outcome was absolute change from baseline in HbA1c at Week 24. Secondary outcomes assessed at Week 24 included the proportion of patients achieving HbA1c < 7.0%, the proportion of patients with gastrointestinal adverse events (GI AEs), and the proportion of patients achieving HbA1c < 7.0% without GI AEs. Safety and tolerability were also assessed in all patients who received ≥1 dose of study medication.

RESULTS

Four-hundred and eighty-eight patients were randomized (1:1) to saxagliptin or acarbose via a central randomization system (interactive voice/web response system); 241 and 244 patients received saxagliptin and acarbose, respectively, and 238 and 243 of these had ≥1 pre- and ≥1 post-baseline efficacy values recorded. Saxagliptin was non-inferior to acarbose for glycaemic control [Week 24 HbA1c change: -0.82% and -0.78%, respectively; difference (95% confidence interval): -0.04 (-0.22, 0.13)%], with similar proportions of patients in both treatment groups achieving HbA1c < 7.0%. However, fewer GI AEs were reported with saxagliptin compared with acarbose, and a greater number of patients who received saxagliptin achieved HbA1c < 7.0% without GI AEs compared with those receiving acarbose.

CONCLUSION

Both therapies had similar efficacy profiles. However, saxagliptin was associated with fewer GI AEs, suggesting it might be preferential for clinical practice.

CLINICAL TRIAL REGISTRATION NUMBER

NCT02243176, clinicaltrials.gov.

Treatment Strategy for Type 2 Diabetes with Obesity: Focus on Glucagon-like Peptide-1 Receptor Agonists

PURPOSE

The progressive nature of type 2 diabetes mellitus (T2DM) calls for step-wise intensification of therapy for maintaining normal glycemic levels and lowering cardiovascular (CV) risk. Because obesity is a prominent risk factor and comorbidity of T2DM, it further elevates the CV risk in T2DM. Therefore, it is vital to manage weight, obesity, and glycemic parameters for effective T2DM management. Few oral antidiabetic drugs (sulfonylureas and thiazolidinediones) and insulin are not suitable for obese patients with T2DM because these drugs cause weight gain. The present review discusses the place of glucagon-like peptide-1 receptor agonists (GLP-1RAs) in the treatment of obese patients with T2DM and the significance of these drugs in the prevention of future CV risk in patients with T2DM.

METHODS

A literature search of PubMed and EMBASE was conducted by using the search terms T2DM, GLP-1RAs, obesity, and cardiovascular complication. Randomized controlled trials measuring the effect of GLP-1RAs versus that of placebo on CV outcomes were included in the review.

FINDINGS

GLP-1RAs have emerged as a therapeutic alternative; these drugs exert their actions by providing glycemic control, improving insulin resistance and ö̇-cell function, and reducing weight. The risk of hypoglycemia with GLP-1RAs is minimal; however, GLP-1RAs are associated with gastrointestinal adverse events and raise concerns regarding pancreatitis. Combining GLP-1RAs with insulin analogues results in higher efficacy, a lowered insulin dose, and reduced insulin-related hypoglycemia and weight gain. Longer acting GLP-1RAs are also associated with improvement in medication adherence. Improvement in CV risk factors such as blood pressure and lipid profile further increases their usability for improving CV outcomes.

IMPLICATIONS

Overall, the properties of GLP-1RAs make them suitable for combination with oral antidiabetic drugs in the early stages of T2DM and with insulins in the later stages for optimizing comprehensive management of the disease.

Cardiovascular outcome studies with incretin-based therapies: Comparison between DPP-4 inhibitors and GLP-1 receptor agonists

Dipeptidyl peptidase-4 inhibitors (DPP-4is) and glucagon-like peptide-1 receptor agonists (GLP-1RAs) represent two distinct classes of incretin-based therapies used for the treatment of type 2 diabetes. Non-inferiority versus placebo was shown in large prospective cardiovascular outcome trials in patients with high cardiovascular risk: SAVOR-TIMI 53 (saxagliptin), EXAMINE (alogliptin), and TECOS (sitagliptin); ELIXA (lixisenatide), LEADER (liraglutide) and SUSTAIN 6 (semaglutide). The promises raised by meta-analyses of phase 2-3 trials with DPP-4is were non confirmed as no cardiovascular protection could be evidenced. However, LEADER showed a significant reduction in major cardiovascular events, myocardial infarction, cardiovascular and all-cause mortality in patients treated by liraglutide compared to placebo. These positive results contrasted with the non-inferiority results with lixisenatide in ELIXA. They were partially confirmed with semaglutide in SUSTAIN 6 despite the absence of reduction in cardiovascular mortality. Hospitalisation for heart failure was not increased except with saxagliptin in SAVOR-TIMI 53. The reasons for different outcomes between trials remain largely unknown as well as the precise underlying mechanisms explaining the cardiovascular protection by liraglutide. The clinical relevance of results with DPP-4is and GLP-1RAs is discussed. Ongoing trials with linagliptin and several once-weekly GLP-1RAs should provide new insights into remaining fundamental questions.

Cardiovascular Safety of Incretin-Based Therapies in Type 2 Diabetes: Systematic Review of Integrated Analyses and Randomized Controlled Trials

Introduction

Regulatory requirements mandate that new drugs for treatment of patients with type 2 diabetes mellitus (T2DM), such as dipeptidyl peptidase-4 (DPP-4) inhibitors and glucagon-like peptide-1 (GLP-1) receptor agonists, are evaluated to show that they do not increase cardiovascular (CV) risk.

Methods

A systematic review was undertaken to evaluate the association between DPP-4 inhibitor and GLP-1 receptor agonist use and major adverse cardiac events (MACE). The National Institutes of Health Medline database was searched for pooled analyses, meta-analyses, and randomized controlled trials (RCTs) of DPP-4 inhibitors and GLP-1 receptor agonists that included CV endpoints.

Results

Thirty-six articles met the inclusion criteria encompassing 11 pooled analyses, 17 meta-analyses, and eight RCTs (including secondary analyses). Over the short term (up to 4 years), patients with T2DM exposed to a DPP-4 inhibitor or GLP-1 receptor agonist were not at increased risk for MACE (or its component endpoints) compared with those who received comparator agents. Two meta-analyses showed a significant reduction in the incidence of MACE associated with DPP-4 inhibitor therapy as a drug class, but this beneficial effect was not observed in other meta-analyses that included large RCT CV outcome studies. In four RCTs that evaluated alogliptin, saxagliptin, sitagliptin, or lixisenatide, there was no overall increased risk for MACE relative to placebo in T2DM patients at high risk for CV events or with established CV disease, although there was an increased rate of hospitalization for heart failure associated with saxagliptin. A fifth RCT showed that liraglutide reduced MACE risk by 13% versus placebo.

Conclusion

Overall, incretin therapy does not appear to increase risk for MACE in the short term.

Effects of dipeptidyl peptidase-4 inhibitors on blood pressure in patients with type 2 diabetes: A systematic review and meta-analysis

This review was undertaken to assess the effects of dipeptidyl peptidase-4 (DPP-4) inhibitors on blood pressure (BP) in patients with type 2 diabetes (T2DM). We searched three main databases (PubMed, Web of Science, and Scopus) for relevant articles. Randomized controlled trials which reported BP changes from baseline to study endpoint in patients with T2DM receiving treatment of DPP-4 inhibitors were included for analysis. Random effects models were used to measure the mean differences with 95% confidence intervals (CIs). Fifteen trials involving 5636 participants were identified. When compared with placebo or nontreatment, DPP-4 inhibitors achieved greater reductions for both SBP (mean difference, -3.04  mmHg; 95% CI, -4.37 to -1.72; P < 0.00001) and DBP (mean difference, -1.47  mmHg; 95% CI, -1.79 to -1.15; P < 0.00001). But the BP-lowering effects of sodium-glucose cotransporter 2 inhibitors were more significant than those of DPP-4 inhibitors for both SBP (mean difference, 4.44  mmHg; 95% CI, 2.67-6.22; P < 0.00001) and DBP (mean difference, 2.15  mmHg; 95% CI, 1.08-3.21; P < 0.00001). No significant differences in BP changes were shown between DPP-4 inhibitors with other antidiabetic agents including glucagon-like peptide 1 receptor agonists, pioglitazone, sulphonylureas, metformin, and α-glucosidase inhibitors. DPP-4 inhibitors may exert modest BP-lowering effects compared with placebo or nontreatment for patients with T2DM, but no significant BP improvement was seen with this drug class when compared with other antidiabetic medications.

Lessons learned from cardiovascular outcome clinical trials with dipeptidyl peptidase 4 (DPP-4) inhibitors

Previous trials of glucose-lowering strategies in subjects with type 2 diabetes have demonstrated a beneficial effect of intensive glycemic control on microvascular complications but failed to show a clear benefit on cardiovascular complications. The findings of meta-analyses of rosiglitazone trials suggesting that rosiglitazone might increase the risk of myocardial infarction have cast doubt on the cardiovascular safety of glucose-lowering drugs. In 2008, the US Food and Drug Administration has implemented rigorous criteria to approve new glucose-lowering drugs, requiring proof of cardiovascular safety. These regulatory requirements have led to a considerable increase in the number of cardiovascular outcome trials in type 2 diabetes to ensure that newer glucose-lowering drugs are not associated with increased cardiovascular risk. Incretin-based therapies including dipeptidyl peptidase 4 (DPP-4) inhibitors, and injectable glucagon-like peptide 1 (GLP-1) receptor agonists are novel treatment options for patients with inadequate glucose control. Although DPP-4 inhibitors have shown neutral effects on risk factors for cardiovascular diseases, it remains unclear whether treatment with these new glucose-lowering agents might be associated with a reduction in cardiovascular events. The results of the three cardiovascular outcome trials comparing DPP-4 inhibitors treatment to placebo in addition to other glucose-lowering drugs have been published. All the three DPP-4 inhibitor cardiovascular outcome trials have shown non-inferiority with regard to cardiovascular safety, compared with placebo, when added to usual care. In this review, we summarize cardiovascular outcome trials of DPP-4 inhibitors, and provide an overview of these trials and their limitations.

Saxagliptin for the treatment of diabetes - a focus on safety

INTRODUCTION

The safety of agents used to treat type 2 diabetes (T2D), a chronic disease requiring life-long intervention, is of particular interest. Saxagliptin is a potent and selective DPP-4 inhibitor that has emerged as a therapeutic option for T2D.

AREAS COVERED

Its safety was assessed in a development program of 20 phase 2/3 randomized clinical trials and in SAVOR-TIMI 53 trial that evaluated the cardiovascular outcomes. In order to capture any further safety signals, mainly in the long-term, a post-marketing safety surveillance is ongoing. This paper discusses the tolerability and safety profile of the agent, including cardiovascular, renal, pancreatic, hepatic and bone adverse events.

EXPERT OPINION

Saxagliptin is a safe therapeutic option for patients with T2D, with low risk of hypoglycemia and good tolerability. It demonstrated cardiovascular safety (including in patients with pre-existing cardiovascular disease and/or HF) and safety with respect to all-cause mortality and adverse events of special interest. In SAVOR-TIMI53, saxagliptin was associated with an unexpected increased risk of HF hospitalization, mainly in the first 12 months; a mechanistic explanation for this has not been found. Further research needs to elucidate the effect of antidiabetic drugs on the heart, by including biomarkers and echocardiographic sub-studies within large outcome trials.

Cardiovascular safety for once-weekly dulaglutide in type 2 diabetes: a pre-specified meta-analysis of prospectively adjudicated cardiovascular events

BACKGROUND

Patients with type 2 diabetes (T2D) have a substantial increased risk for cardiovascular (CV) disease and associated mortality than those without diabetes. Dulaglutide is a once-weekly glucagon-like peptide-1 receptor agonist that is approved for treatment of T2D.

METHODS

This meta-analysis evaluates the CV risk in patients with T2D treated with dulaglutide in 9 randomized safety and efficacy trials. Mean (median) treatment duration was 333 (358) days. Reported CV events were independently adjudicated by a treatment-blinded clinical endpoint committee. The primary measure was a 4-component major adverse CV event (4-component MACE) composite endpoint of death due to CV causes, nonfatal myocardial infarction (MI), nonfatal stroke, or hospitalization for unstable angina. Additional pre-specified endpoints included adjudicated coronary revascularizations, hospitalization for heart failure, and all-cause mortality. A Cox proportional hazards regression model (stratified by study) was used to estimate the hazard ratio (HR) and confidence interval (CI). Tests of treatment effects for the primary endpoint were conducted at a 2-sided alpha level of 0.0198 and a corresponding 98.02 % CI was calculated. Statistical heterogeneity between the strata (studies) was tested by including in the Cox model an interaction term between treatment and strata.

RESULTS

The analysis included 6010 randomized patients [dulaglutide: 3885; comparator therapy (active or placebo): 2125]; cumulative exposure to dulaglutide or comparator therapy was 3941 and 2223 patient-years, respectively. The demographic and baseline CV disease characteristics were similar across groups. Twenty-six (0.67 %) patients in the dulaglutide group versus 25 (1.18 %) in the comparator group experienced a primary 4-component MACE (HR 0.57; adjusted 98.02 % CI 0.30, 1.10). Results for the 3-component MACE (composite endpoint of death due to CV causes, nonfatal MI or stroke), 6-component MACE (composite endpoint of death due to CV causes, nonfatal MI or stroke, hospitalization for unstable angina or heart failure, or coronary revascularizations) and all-cause mortality were consistent with the primary analysis (HR < 1.0 for all).

CONCLUSIONS

These results suggest that dulaglutide does not increase the risk of major CV events in T2D patients. The ongoing CV outcomes study, Researching CV Events with a Weekly Incretin in Diabetes (REWIND), will further assess CV safety of dulaglutide.

Dipeptidyl Peptidase 4 Inhibitors and the Risk of Cardiovascular Disease in Patients with Type 2 Diabetes: A Tale of Three Studies

Dipeptidyl peptidase 4 (DPP4) inhibitors have been touted as promising antihyperglycemic agents due to their beneficial effects on glycemia without inducing hypoglycemia or body weight gain and their good tolerability. Beyond their glucose-lowering effects, numerous clinical trials and experimental studies have suggested that DPP4 inhibitors may exert cardioprotective effects through their pleiotropic actions via glucagon-like peptide 1-dependent mechanisms or involving other substrates. Since 2008, regulatory agencies have required an assessment of cardiovascular disease (CVD) safety for the approval of all new anti-hyperglycemic agents, including incretin-based therapies. Three large prospective DPP4 inhibitor trials with cardiovascular (CV) outcomes have recently been published. According to the Saxagliptin Assessment of Vascular Outcomes Recorded in Patients with Diabetes Mellitus (SAVOR-TIMI 53) and EXamination of cArdiovascular outcoMes with alogliptIN versus standard of carE in patients with type 2 diabetes mellitus and acute coronary syndrome (EXAMINE) trials, DPP4 inhibitors, including saxagliptin and alogliptin, did not appear to increase the risk of CV events in patients with type 2 diabetes and established CVD or high risk factors. Unexpectedly, saxagliptin significantly increased the risk of hospitalization for heart failure by 27%, a finding that has not been explained and that requires further exploration. More recently, the Trial Evaluating Cardiovascular Outcomes with Sitagliptin (TECOS) trial demonstrated the CV safety of sitagliptin, including assessments of the primary composite CV endpoint and hospitalization for heart failure in patients with type 2 diabetes and established CVD. The CV outcomes of an ongoing linagliptin trial are expected to provide new evidence about the CV effects of a DPP4-inhibitor in patients with type 2 diabetes.

Pleiotropic effects of the dipeptidylpeptidase-4 inhibitors on the cardiovascular system

Dipeptidylpeptidase-4 (DPP-4) is a ubiquitously expressed transmembrane protein that removes NH2-terminal dipeptides from various substrate hormones, chemokines, neuropeptides, and growth factors. Two known substrates of DPP-4 include the incretin hormones glucagon-like peptide-1 (GLP-1) and gastric inhibitory peptide, which are secreted by enteroendocrine cells in response to postprandial hyperglycemia and account for 60–70% of postprandial insulin secretion. DPP-4 inhibitors (DPP-4i) block degradation of GLP-1 and gastric inhibitory peptide, extend their insulinotropic effect, and improve glycemia. Since 2006, several DPP-4i have become available for treatment of type 2 diabetes mellitus. Clinical trials confirm that DPP-4i raises GLP-1 levels in plasma and improves glycemia with very low risk for hypoglycemia and other side effects. Recent studies also suggest that DPP-4i confers cardiovascular and kidney protection, beyond glycemic control, which may reduce the risk for further development of the multiple comorbidities associated with obesity/type 2 diabetes mellitus, including hypertension and cardiovascular disease (CVD) and kidney disease. The notion that DPP-4i may improve CVD outcomes by mechanisms beyond glycemic control is due to both GLP-1-dependent and GLP-1-independent effects. The CVD protective effects by DPP-4i result from multiple factors including insulin resistance, oxidative stress, dyslipidemia, adipose tissue dysfunction, dysfunctional immunity, and antiapoptotic properties of these agents in the heart and vasculature. This review focuses on cellular and molecular mechanisms mediating the CVD protective effects of DPP-4i beyond favorable effects on glycemic control.

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

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

Safety of dipeptidyl peptidase-4 inhibitors for treating type 2 diabetes

INTRODUCTION

Dipeptidyl peptidase-4 (DPP-4) inhibitors (gliptins) occupy a growing place in the armamentarium of drugs used for the management of hyperglycemia in type 2 diabetes, although some safety concerns have been raised in recent years.

AREAS COVERED

An updated review providing an analysis of available safety data (meta-analyses, randomized controlled trials, observational cohort and case-control studies and pharmacovigilance reports) with five commercialized DPP-4 inhibitors (sitagliptin, vildagliptin, saxagliptin, alogliptin, linagliptin). A special focus is given to overall safety profile; pancreatic adverse events (AEs) (acute pancreatitis, pancreatic cancer); overall cardiovascular safety (myocardial infarction and stroke); congestive heart failure concern and finally, safety in special populations (elderly, renal impairment).

EXPERT OPINION

The good tolerance/safety profile of DPP-4 inhibitors has been largely confirmed, including in more fragile populations (elderly, renal impairment) with almost no increased risk of infection or gastrointestinal AEs, no weight gain and a minimal risk of hypoglycemia. Although an increased risk of acute pancreatitis and pancreatic cancer was suspected, the complete set of available data appears reassuring so far. Cardiovascular safety of DPP-4 inhibitors has been proven but an unexpected increased risk of heart failure has been reported which should be confirmed in ongoing trials and better understood. Further postmarketing surveillance is recommended.

Saxagliptin efficacy and safety in patients with type 2 diabetes receiving concomitant statin therapy

AIMS

To examine whether concomitant statin therapy affects glycemic control with saxagliptin 2.5 and 5mg/d in patients with type 2 diabetes mellitus (T2DM).

METHODS

Efficacy and safety were analyzed post hoc for pooled data from 9 saxagliptin randomized, placebo-controlled trials with a primary 24-week treatment period (4 monotherapy, 2 add-on to metformin, 1 each add-on to a sulfonylurea, thiazolidinedione, or insulin±metformin). Safety was also assessed in an 11-study, 24-week pool and an extended 20-study pool, which included 9 additional 4- to 52-week randomized studies. Comparisons were performed for patient groups defined by baseline statin use.

RESULTS

Saxagliptin produced greater mean reductions in glycated hemoglobin than placebo, with no interaction between treatment and baseline statin use (P=0.47). In patients receiving saxagliptin 2.5 and 5mg and placebo, the proportion of patients with ≥1 adverse event (AE) was 78.1%, 64.0%, and 63.2%, respectively, in patients with any statin use and 70.6%, 57.9%, and 55.0% in patients with no statin use. Serious AEs, deaths, and symptomatic confirmed hypoglycemia (fingerstick glucose ≤50mg/dL) were few and similar, irrespective of baseline statin use.

CONCLUSIONS

Saxagliptin improves glycemic control and is generally well tolerated in patients with T2DM, irrespective of concomitant statin therapy.

Extra-pancreatic effects of incretin-based therapies

Glucagon-like peptide-1 (GLP-1) stimulates insulin secretion and inhibits glucagon secretion in the pancreatic islets of Langerhans under hyperglycaemia. In type 2 diabetes (T2DM), GLP-1 improves glycaemic control without a hypoglycaemia risk. GLP-1 receptors have also been found in extra-pancreatic tissues, e.g., the cardiovascular system, the gastrointestinal system, and the central nervous system. Since cardiovascular comorbidities and degenerative neurological changes are associated with T2DM, the interest in the extrapancreatic effects of GLP-1 has increased. GLP-1-based therapies with either GLP-1 receptor agonists (GLP-1 RA) or DPP-4 inhibitors (that delay the degradation of endogenous GLP-1) have become widely used therapeutic options in T2DM. In clinical studies, GLP-1 RA have demonstrated a significant lowering of blood pressure that is independent of body weight changes. Preclinical data and small short-term studies with GLP-1 and GLP-1 RA have shown cardioprotective effects in ischaemia models. GLP-1 as well as a treatment with GLP-1 RA also induces a stable body weight loss by affecting GLP-1 signaling in the hypothalamus and by slowing gastric emptying. Regarding neuroprotective actions in degenerative neurological disease models for Parkinson's- or Alzheimer's disease or neurovascular complications like stroke, animal studies have shown positive results. In this article, a summary of the extrapancreatic effects of GLP-1 and GLP-1-based therapies is presented.

The effects of dipeptidyl peptidase-4 inhibition on microvascular diabetes complications

We performed a review of the literature to determine whether the dipeptidyl peptidase-4 inhibitors (DPP4-I) may have the capability to directly and positively influence diabetic microvascular complications. The literature was scanned to identify experimental and clinical evidence that DPP4-I can ameliorate diabetic microangiopathy. We retrieved articles published between 1 January 1980 and 1 March 2014 in English-language peer-reviewed journals using the following terms: ("diabetes" OR "diabetic") AND ("retinopathy" OR "retinal" OR "nephropathy" OR "renal" OR "albuminuria" OR "microalbuminuria" OR "neuropathy" OR "ulcer" OR "wound" OR "bone marrow"); ("dipeptidyl peptidase-4" OR "dipeptidyl peptidase-IV" OR "DPP-4" OR "DPP-IV"); and ("inhibition" OR "inhibitor"). Experimentally, DPP4-I appears to improve inflammation, endothelial function, blood pressure, lipid metabolism, and bone marrow function. Several experimental studies report direct potential beneficial effects of DPP4-I on all microvascular diabetes-related complications. These drugs have the ability to act either directly or indirectly via improved glucose control, GLP-1 bioavailability, and modifying nonincretin substrates. Although preliminary clinical data support that DPP4-I therapy can protect from microangiopathy, insufficient evidence is available to conclude that this class of drugs directly prevents or decreases microangiopathy in humans independently from improved glucose control. Experimental findings and preliminary clinical data suggest that DPP4-I, in addition to improving metabolic control, have the potential to interfere with the onset and progression of diabetic microangiopathy. Further evidence is needed to confirm these effects in patients with diabetes.

Efficacy and safety of saxagliptin as add-on therapy in type 2 diabetes

Combination therapy for type 2 diabetes using agents with complementary mechanisms of action may improve glycemic control to a greater extent than monotherapy and allow the use of lower doses of antihyperglycemic medications. Dipeptidyl peptidase-4 inhibitors, including saxagliptin, are recommended as add-on therapy to metformin and as part of two- or three-drug combinations in patients not meeting individualized glycemic goals with metformin alone or as part of a dual-therapy regimen. This article reviews the efficacy and safety of saxagliptin as an add-on therapy to metformin, glyburide, a thiazolidinedione, or insulin (with or without metformin) and as a component of triple therapy with metformin and a sulfonylurea.

Understanding the type 2 diabetes mellitus and cardiovascular disease risk paradox

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

The extra-pancreatic effects of GLP-1 receptor agonists: a focus on the cardiovascular, gastrointestinal and central nervous systems

The glucagon-like peptide-1 receptor agonists (GLP-1RAs) exenatide, liraglutide and lixisenatide have been shown to improve glycaemic control and beta-cell function with a low risk of hypoglycaemia in people with type 2 diabetes. GLP-1 receptors are also expressed in extra-pancreatic tissues and trial data suggest that GLP-1RAs also have effects beyond their glycaemic actions. Preclinical studies using native GLP-1 or GLP-1RAs provide substantial evidence for cardioprotective effects, while clinical trial data have shown beneficial actions on hypertension and dyslipidaemia in people with type 2 diabetes. Significant weight loss has been reported with GLP-1RAs in both people with type 2 diabetes and obese people without diabetes. GLP-1RAs also slow down gastric emptying, but preclinical data suggest that the main mechanism behind GLP-1RA-induced weight loss is more likely to involve their effects on appetite signalling in the brain. GLP-1RAs have also been shown to exert a neuroprotective role in rodent models of stroke, Alzheimer's disease and Parkinson's disease. These extra-pancreatic effects of GLP-1RAs could provide multi-factorial benefits to people with type 2 diabetes. Potential adverse effects of GLP-1RA treatment are usually manageable but may include gastrointestinal effects, increased heart rate and renal injury. While extensive further research is still required, early data suggest that GLP-1RAs may also have the potential to favourably impact cardiovascular disease, obesity or neurological disorders in people without diabetes in the future.

The dipeptidyl peptidase-4 inhibitor saxagliptin improves function of circulating pro-angiogenic cells from type 2 diabetic patients

BACKGROUND

Type 2 diabetes (T2D) is associated with reduction and dysfunction of circulating pro-angiogenic cells (PACs). DPP-4 inhibitors, a class of oral agents for T2D, might possess pleiotropic vasculoprotective activities. Herein, we tested whether DPP-4 inhibition with Saxagliptin affects the function of circulating PACs from T2D and healthy subjects.

METHODS

PACs were isolated from T2D (n = 20) and healthy (n = 20) subjects. Gene expression, clonogenesis, proliferation, adhesion, migration and tubulisation were assessed in vitro by incubating PACs with or without Saxagliptin and SDF-1α. Stimulation of angiogenesis by circulating cells from T2D patients treated with Saxagliptin or other non-incretinergic drugs was assessed in vivo using animal models.

RESULTS

Soluble DPP-4 activity was predominant over cellular activity and was successfully inhibited by Saxagliptin. At baseline, T2D compared to healthy PACs contained less acLDL(+)Lectin(+) cells, and showed altered expression of genes related to adhesion and cell cycle regulation. This was reflected by impaired adhesion and clonogenesis/proliferative response of T2D PACs. Saxagliptin + SDF-1α improved adhesion and tube sustaining capacity of PACs from T2D patients. CD14+ PACs were more responsive to Saxagliptin than CD14- PACs. While Saxagliptin modestly reduced angiogenesis by mature endothelial cells, circulating PACs-progeny cells from T2D patients on Saxagliptin treatment displayed higher growth factor-inducible in vivo angiogenetic activity, compared to cells from T2D patients on non-incretinergic regimen.

CONCLUSIONS

Saxagliptin reverses PACs dysfunction associated with T2D in vitro and improves inducible angiogenesis by circulating cells in vivo. These data add knowledge to the potential pleiotropic cardiovascular effects of DPP-4 inhibition.

Reshaping diabetes care: the fundamental role of dipeptidyl peptidase-4 inhibitors and glucagon-like peptide-1 receptor agonists in clinical practice

OBJECTIVE

To update clinicians on the most recent safety and efficacy data on current incretin-based strategies for the treatment of type 2 diabetes (T2D).

METHODS

Title searches were conducted in the Pubmed database to identify literature pertaining to the safety and efficacy of glucagon-like peptide-1 receptor agonists (GLP-1RAs) and dipeptidyl peptidase-4 (DPP-4) inhibitors. Product-specific title searches included the terms exenatide, liraglutide, linagliptin, saxagliptin, sitagliptin, and vildagliptin.

RESULTS

The recent literature has introduced us to newer DPP-4 inhibitors and longer-acting GLP-1RAs, updated meta-analyses assessing the safety and efficacy of incretin-based therapies, and studies exploring the use of incretin-based treatments in broader clinical settings such as combination therapy with insulin. Meta-analyses have demonstrated placebo-adjusted glycated hemoglobin (HbA1c) reductions of ~1% with GLP-1RAs and 0.6 to 0.8% with DPP-4 inhibitors and have suggested cardioprotective effects such as reduction of cardiovascular events and improvement of lipid profile. As a class, these agents have consistently demonstrated low risks of hypoglycemia relative to other agents.

CONCLUSION

Incretin-based therapies are characterized by an overall favorable safety profile and weight effect, a low risk of hypoglycemia, and clinically meaningful improvements in HbA1c. Based on an expanding and favorable literature describing their use in various patient populations, the guidelines of the American Association of Clinical Endocrinologists and the recently updated guidelines from the American Diabetes Association assign these agents a central role in the treatment of T2D.

Dipeptidyl peptidase-4 inhibitors and their effects on the cardiovascular system

It is well known that patients with type 2 diabetes mellitus (T2DM) are at increased risk of cardiovascular (CV) disease. Elevated plasma glucose levels that independently lead to increased cardiovascular risk, combined with associated co-morbidities such as obesity, hypertension, and dyslipidemia, further contribute to the development of CV complications. Dipeptidyl peptidase 4 inhibitors (DPP-4 inhibitors) are a relatively new class of drugs used for the treatment of diabetes and recently have been widely used in clinical practice. They exert their actions through degradation inhibition of endogenous glucagon-like peptides (GLP-1) and glucose-dependent insulinotropic peptides (GIP), with a resulting increase in glucose mediated insulin secretion and a suppression of glucagon secretion. Since GLP-1 is known to have an impact not only on plasma glucose levels but also to have cardiovascular protective effects there is increased speculation of whether DPP-4 inhibitors will have similar effects. Though many short-term studies have been encouraging, ongoing long-term clinical trials on humans are needed to provide further clarity to the complete safety profiles of these agents in terms of cardiovascular risk, and whether they may exert potential cardiovascular benefit. This review includes available data on the cardiovascular effects of DPP-4 inhibitors as well as their overall safety profile.

Dipeptidyl-peptidase 4 inhibition: linking metabolic control to cardiovascular protection

Dipeptidyl peptidases 4 (DPP4) inhibitors are a new class of oral anti-hyperglycemic drugs for the treatment of type 2 diabetes (T2DM). They are also called "incretins" because they act by inhibiting the degradation of endogenous incretin hormones, in particular GLP-1, that mediates their main metabolic effects. DPP4 is an ubiquitous protease that regulates not only glucose and lipid metabolism, but also exhibits several systemic effects at different site levels. DPP4 inhibition improves endothelial function, reduces the pro-oxidative and the pro-inflammatory state, and exerts renal effects. These actions are mediated by different DPP4 ligands, such as cytokines, growth factors, neuotransmitters etc. Clinical and experimental studies have demonstrated that DPP4 inhibitors are efficient in protecting cardiac, renal and vascular systems, through antiatherosclerotic and vasculoprotective mechanisms. For these reasons DDP4 inhibitors are thought to be "cardiovascular protective" as well as anti-diabetic drugs. Clinical trials aimed to demonstrate the efficacy of DPP4 inhibitors in reducing cardiovascular events, independent of their anti-hyperglycemic action, are ongoing. These trials will also give necessary information on their safety.

Cardiovascular actions of GLP-1 and incretin-based pharmacotherapy

Incretin-based therapy became recently available as antihyperglycemic treatment for patients with type 2 diabetes (T2DM). Incretin therapy comprises glucagon-like peptide receptor agonists (GLP-1RA) and dipeptidyl-peptidase 4 inhibitors (DPP4-I): these classes of drugs not only have the ability to reduce blood glucose, but also can exert several cardioprotective effects. They have been shown to positively influence some risk factors for cardiovascular disease (CVD), to improve endothelial function, and to directly affect cardiac function. For these reasons incretins are considered not only antidiabetic drugs, but also cardiovascular effective. The first clinical trials aimed to demonstrate the safety of DPP4 inhibitors have been recently published: their clinical significance will be discussed in light of the prior experimental findings.

Incretin-based therapies: focus on effects beyond glycemic control alone

Type 2 diabetes is associated with a high prevalence of comorbidities resulting from hypertension, dyslipidemia, and hyperglycemia. Inadequate management of these risk factors will eventually result in detrimental health consequences. Thus, the effect of a drug on factors such as weight, cardiovascular (CV) risk factors, and adherence is important to consider. A review was undertaken of the recent medical literature describing the extraglycemic characteristics of the two classes of incretin-based therapies-glucagon-like peptide-1 receptor agonists (GLP-1RA) and dipeptidyl peptidase-4 (DPP-4) inhibitors. PubMed searches were performed to identify published data on incretin therapies that describe their effects on CV risk factors, CV events, and factors related to medication adherence. The maintenance or loss of weight associated with the use of GLP-1RAs and DPP-4 inhibitors is well described in the medical literature. These agents also appear to be associated with a modest decrease in blood pressure and a reduced risk of CV events. In addition, several characteristics of incretin therapies may improve rates of medication adherence, such as generally favorable tolerability profiles (particularly with DPP-4 inhibitors), the availability of formulations that simplify treatment regimens, and a low risk for hypoglycemia. The literature on incretin therapies describes a number of clinical characteristics that are relevant to the management of extraglycemic risk factors. As part of a holistic treatment strategy, these properties constitute important considerations for tailoring therapy to individual patients with type 2 diabetes.

Linagliptin as add-on therapy to insulin for patients with type 2 diabetes

Type 2 diabetes mellitus (T2DM) is a highly prevalent, progressive disease that often is poorly controlled. The combination of an incretin-based therapy and insulin is a promising approach to optimize the management of glycemic control without hypoglycemia and weight gain. Linagliptin, a recently approved oral dipeptidyl peptidase-4 inhibitor, has a unique pharmacological profile. The convenient, once-daily dosing does not need adjustment in patients with hepatic and/or renal impairment. In clinical studies linagliptin shows an important reduction of blood glucose with an overall safety profile similar to that of placebo. So far, the combination of linagliptin and insulin has been tested in three major clinical studies in different populations. It has been shown that linagliptin is an effective and safe add-on therapy to insulin in patients with T2DM. The efficacy and safety of this combination was also shown in vulnerable, elderly T2DM patients and in patients with T2DM and renal impairment. Favorable effects regarding the counteraction of hypoglycemia make linagliptin especially interesting as an add-on therapy to insulin. This review aims to present the existing clinical studies on the efficacy and safety of linagliptin as add-on therapy to insulin in patients with T2DM in the context of current literature. Additionally, the possible advantages of linagliptin as an add-on therapy to insulin in relation to cardiovascular safety, patient-centered therapy and the prevention of hypoglycemia, are discussed.

The activity of circulating dipeptidyl peptidase-4 is associated with subclinical left ventricular dysfunction in patients with type 2 diabetes mellitus

Background

Patients with type 2 diabetes mellitus (T2DM) present subclinical left ventricular systolic and/or diastolic dysfunction (LVD). Dipeptidyl peptidase-4 (DPP4) inactivates peptides that possess cardioprotective actions. Our aim was to analyze whether the activity of circulating DPP4 is associated with echocardiographically defined LVD in asymptomatic patients with T2DM.

Methods

In this cross-sectional study, we examined 83 T2DM patients with no coronary or valve heart disease and 59 age and gender-matched non-diabetic subjects. Plasma DPP4 activity (DPP4a) was measured by enzymatic assay and serum amino-terminal pro-brain natriuretic peptide (NT-proBNP) was measured by enzyme-linked immunosorbent assay. LV function was assessed by two-dimensional echocardiographic imaging, targeted M-mode recordings and Doppler ultrasound measurements. Differences in means were assessed by t-tests and one-way ANOVA. Associations were assessed by adjusted multiple linear regression and logistic regression analyses.

Results

DPP4a was increased in T2DM patients as compared with non-diabetic subjects (5855 ± 1632 vs 5208 ± 957 pmol/min/mL, p < 0.05). Clinical characteristics and echocardiographic parameters assessing LV morphology were similar across DPP4a tertiles in T2DM patients. However, prevalence of LVD progressively increased across incremental DPP4a tertiles (13%, 39% and 71%, all p < 0.001). Multivariate regression analysis confirmed the independent associations of DPP4a with LVD in T2DM patients (p < 0.05). Similarly, multiple logistic regression analysis showed that an increase of 100 pmol/min/min plasma DPP4a was independently associated with an increased frequency of LVD with an adjusted odds ratio of 1.10 (95% CI, 1.04 to 1.15, p = 0.001).

Conclusions

An excessive activity of circulating DPP4 is independently associated with subclinical LVD in T2DM patients. Albeit descriptive, these findings suggest that DPP4 may be involved in the mechanisms of LVD in T2DM.

Novel therapies for the management of type 2 diabetes mellitus: Part 2. Addressing the incretin defect in the clinical setting in 2013

The present short review summarizes and updates clinical experience with two classes of drugs introduced for the management of type 2 diabetes mellitus over the past 8 years: (i) the glucagon-like peptide-1 receptor agonists; and (ii) the dipeptidyl peptidase 4 inhibitors. Both classes of agents address the so called "incretin defect" in patients with T2DM.

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.

Sodium-glucose co-transporter 2 inhibitors and the potential for cardiovascular risk reduction in patients with type 2 diabetes mellitus

BACKGROUND

Clinical development programs of investigational antidiabetic agents now include evaluation of cardiovascular (CV) risk as a major research focus. Recently, several compounds in a new class of antihyperglycemic therapy have reached the final stages of development. Treatment with inhibitors of sodium-glucose co-transporters 2 (SGLT2) leads to urinary excretion of glucose in patients with type 2 diabetes mellitus (T2DM), and is associated with clinically significant reductions in blood glucose levels. The glucosuria-based mechanism of this class has the potential to induce weight loss through reduced caloric availability, and, in addition, may affect blood pressure (BP) via osmotic diuresis or other as yet incompletely characterized mechanisms.

METHODS

Searches of the PubMed database were conducted for published studies evaluating the use of SGLT2 inhibitors that reported data on CV risk factors (eg, weight, BP, lipid levels) or CV events. Searches for presentations at recent major diabetes congresses were performed using the Online Submission and Invitation System.

RESULTS

Treatment with SGLT2 inhibitors has consistently been associated with reduction in body weight and BP. Qualitative graphical assessment of 21 studies shows unadjusted reductions in systolic BP and body weight typically ranging between 3 to 5 mm Hg and 2 to 3 kg, respectively. A few reports have suggested the potential for improvement in lipid parameters, such as high-density lipoprotein cholesterol levels; however, not all studies have demonstrated significant changes, and some have noted small increases in low-density lipoprotein cholesterol levels.

CONCLUSION

Inhibition of SGLT2 in patients with T2DM may be associated with significant weight loss and BP reduction that are sustainable over the average time span of an investigational clinical study (ie, 3-6 months). When considered in terms of the potential for combination therapy, these features may offer a means of further reducing metabolic and CV risk in patients with T2DM.

A practice-based approach to the 2012 position statement of the American Diabetes Association and the European Association for the Study of Diabetes

The position statement on the management of hyperglycemia in patients with type 2 diabetes mellitus issued in 2012 by the American Diabetes Association and the European Association for the Study of Diabetes contains significant improvements over the 2009 version, including an emphasis on patient-centered care, enhanced strategies for lifestyle modification, a focus on comprehensive cardiovascular risk reduction, and increased pharmacotherapy choices. As diabetes management evolves over time, further improvements may be made in future consensus statements, including a focus on prevention and early treatment and improved glycemic control in all patients, including those with comorbidities. These goals will be achievable by waning use of therapies known to cause hypoglycemia and weight gain and the increased use of therapies that do not carry these risks.

Safety and tolerability of sitagliptin in type 2 diabetes: pooled analysis of 25 clinical studies

INTRODUCTION

In a previous pooled analysis of 19 double-blind clinical studies conducted by Merck, which included data available as of July 2009 on 10,246 patients with type 2 diabetes (T2DM), treatment with sitagliptin was shown to be generally well tolerated compared with treatment with control agents. As the sitagliptin clinical development program continues, additional studies with sitagliptin have been completed. The present analysis updates the safety and tolerability assessment of sitagliptin by examining pooled data from 25 double-blind clinical studies.

METHODS

The present analysis included data from 14,611 patients in 25 studies with T2DM who received either sitagliptin 100 mg/day (n = 7,726; sitagliptin group) or a comparator agent (n = 6,885; non-exposed group). These studies represent all randomized, double-blind trials conducted by Merck that included patients treated with the usual clinical dose of sitagliptin (100 mg/day) for between 12 weeks and 2 years, and for which results were available as of December 2011. These studies assessed sitagliptin, versus comparator agents, taken as monotherapy, initial combination therapy with metformin or pioglitazone, or as add-on combination therapy with other antihyperglycemic agents (metformin, pioglitazone, a sulfonylurea ± metformin, insulin ± metformin, or metformin + pioglitazone or rosiglitazone). Patient-level data from each study were used to evaluate between-group differences in the exposure-adjusted incidence rates of adverse events (AEs).

RESULTS

Overall incidence rates of AEs and drug-related AEs were higher in the non-exposed group compared with the sitagliptin group. Incidence rates of specific AEs were generally similar between the two groups, except for higher incidence rates of hypoglycemia related to the greater use of a sulfonylurea and diarrhea related to the greater use of metformin in the non-exposed group, and of constipation in the sitagliptin group. Treatment with sitagliptin was not associated with an increased risk of major adverse cardiovascular events, malignancy, or pancreatitis.

CONCLUSION

In this updated pooled safety analysis of data from 14,611 patients with T2DM, sitagliptin 100 mg/day was generally well tolerated in clinical trials of up to 2 years in duration.