Safety and tolerability of sitagliptin in clinical studies: a pooled analysis of data from 10,246 patients with type 2 diabetes

A Rare Case Report of Sitagliptin-Induced Angioedema

Sitagliptin, a dipeptidyl peptidase-4 inhibitor, is used for the treatment of type 2 diabetes mellitus. Sitagliptin-induced angioedema has increased with the simultaneous use of angiotensin receptor blockers and angiotensin-converting enzyme inhibitors. We present a rare case of a 50-year-old female diagnosed with sitagliptin-induced angioedema. On examination, she had both upper and lower lip swelling without any respiratory compromise. On further investigation, her C1 esterase inhibitor level was normal. After stopping sitagliptin, her symptoms resolved. Thus, cautious use of dipeptidyl peptidase-4 inhibitor is advised.

Regulation and Dysregulation of Endothelial Permeability during Systemic Inflammation

Systemic inflammation can be triggered by infection, surgery, trauma or burns. During systemic inflammation, an overshooting immune response induces tissue damage resulting in organ dysfunction and mortality. Endothelial cells make up the inner lining of all blood vessels and are critically involved in maintaining organ integrity by regulating tissue perfusion. Permeability of the endothelial monolayer is strictly controlled and highly organ-specific, forming continuous, fenestrated and discontinuous capillaries that orchestrate the extravasation of fluids, proteins and solutes to maintain organ homeostasis. In the physiological state, the endothelial barrier is maintained by the glycocalyx, extracellular matrix and intercellular junctions including adherens and tight junctions. As endothelial cells are constantly sensing and responding to the extracellular environment, their activation by inflammatory stimuli promotes a loss of endothelial barrier function, which has been identified as a hallmark of systemic inflammation, leading to tissue edema formation and hypotension and thus, is a key contributor to lethal outcomes. In this review, we provide a comprehensive summary of the major players, such as the angiopoietin-Tie2 signaling axis, adrenomedullin and vascular endothelial (VE-) cadherin, that substantially contribute to the regulation and dysregulation of endothelial permeability during systemic inflammation and elucidate treatment strategies targeting the preservation of vascular integrity.

Targeting Procalcitonin Protects Vascular Barrier Integrity

RATIONALE

Capillary leakage frequently occurs during sepsis and after major surgery and is associated with microvascular dysfunction and adverse outcome. Procalcitonin is a well-established biomarker in inflammation without known impact on vascular integrity.

OBJECTIVE

We determined how procalcitonin induces endothelial hyperpermeability and how targeting procalcitonin protects vascular barrier integrity.

METHODS

In a prospective observational clinical study, procalcitonin levels were assessed in 50 cardiac surgery patients and correlated to postoperative fluid and vasopressor requirements along with sublingual microvascular functionality. Effects of the procalcitonin signaling pathway on endothelial barrier and adherens junctional integrity were characterized in vitro and verified in mice. Inhibition of procalcitonin activation by dipeptidyl-peptidase 4 (DPP4) was evaluated in murine polymicrobial sepsis and clinically verified in cardiac surgery patients chronically taking the DPP4 inhibitor sitagliptin.

MEASUREMENTS AND MAIN RESULTS

Elevated postoperative procalcitonin levels identified patients with 2-fold increased fluid requirements (P<0.01), 1.8-fold higher vasopressor demand (P<0.05) and compromised microcirculation (reduction to 63.5±2.8% of perfused vessels, P<0.05). Procalcitonin induced 1.4-fold endothelial and 2.3-fold pulmonary capillary permeability (both P<0.001) by destabilizing VE-cadherin. Procalcitonin effects were dependent on activation by DPP4 and targeting the procalcitonin receptor or DPP4 during sepsis-induced hyperprocalcitonemia reduced capillary leakage by 54±10.1% and 60.4±6.9% (both P<0.01), respectively. Sitagliptin prior to cardiac surgery was associated with augmented microcirculation (74.1±1.7% vs. 68.6±1.9% perfused vessels in sitagliptin non-medicated patients, P<0.05) and 2.3-fold decreased fluid (P<0.05) and 1.8-fold reduced vasopressor demand postoperatively (P<0.05).

CONCLUSION

Targeting procalcitonin's action on the endothelium is a feasible means to preserve vascular integrity during systemic inflammation associated with hyperprocalcitonemia.

DPP4 Regulates DHCR24-Mediated Cholesterol Biosynthesis to Promote Methotrexate Resistance in Gestational Trophoblastic Neoplastic Cells

Metabolic reprogramming could promote cellular adaptation in response to chemotherapeutic drugs in cancer cells. Herein, we aimed to characterize the metabolomic profiles regulated by Dipeptidyl Peptidase 4 (DPP4) in methotrexate (MTX)-resistant gestational trophoblastic neoplastic (GTN) cells. A total of eighty metabolites were found to be commonly altered in DPP4-depleted JAR/MTX and JEG3/MTX cells. Cholesterol biosynthesis-related metabolites were markedly impacted by DPP4 knockdown in MTX-resistant sublines. Manipulation of DPP4 expression remarkably affected the level of cellular cholesterol in GTN cells. Our analysis also identified 24-Dehydrocholesterol Reductase (DHCR24) as a potential downstream effector of DPP4. Manipulation of DHCR24 expression affected cellular cholesterol level, reactive oxygen species (ROS) accumulation, and chemosensitivity to MTX in GTN cell models. In addition, over-expression of DHCR24 could markedly restore cellular cholesterol level and rescue cell survival in DPP4-depleted MTX-resistant GTN cells. Highly correlated expression of DPP4 and DHCR24 was observed in clinical GTN specimens. Further, DPP4 inhibitor sitagliptin effectively inhibited cholesterol biosynthesis, reduced DHCR24 expression and enhanced MTX-induced cytotoxicity in vitro and in vivo. In conclusion, our findings suggested that DPP4 might regulate DHCR24-mediated cholesterol biosynthesis to promote methotrexate resistance in GTN cells. Targeting DPP4/DHCR24 signaling might help to sensitize MTX-resistant GTN to MTX treatment.

Angioedema associated with dipeptidyl peptidase-IV inhibitors

Background

Dipeptidyl peptidase-IV (DPP-IV) inhibitors, also known as gliptins, are a class of oral antidiabetic agents. Postmarketing reports have documented the occurrence of angioedema in patients treated with gliptins and it was found that these drugs increased the risk of angioedema in patients concurrently treated with angiotensin-converting enzyme inhibitors (ACEIs). The aim of this manuscript is to provide an overview of the risk of angioedema associated with gliptins.

Methods

The keywords used for the literature search in the PubMed database included “angioedema” and “dipeptidyl peptidase”, “gliptins”, or the name of each DPP-IV inhibitor. Articles in English published up to December 2020 were taken into consideration.

Results

The available data appear to rule out a higher risk of angioedema associated with gliptin monotherapy and have revealed an increased susceptibility in patients simultaneously treated with gliptins and ACEIs. However, one single multicenter phase IV trial and case reports, even if very limited in number, have shown that angioedema can also occur during treatment with DPP-IV inhibitors without the concomitant use of ACEIs. The involvement of other drugs and drug interactions has occasionally been suggested. In a few patients, deficiency of enzymes involved in bradykinin catabolism was detected and this finding can constitute a risk factor for angioedema exacerbated by treatment with DPP-IV inhibitors.

Conclusions

This risk of angioedema associated with the use of gliptins has mostly been related to the concurrent administration of ACEIs, and has been considered rare, but it might be underestimated and underreported. The role of additional risk factors or drug interactions deserves further investigations. Caution should be taken when considering the use of DPP-IV inhibitors in patients treated with ACEIs or presenting with other known risk factors for angioedema.

Factors influencing on development of COVID-19 pneumonia and association with oral anti-diabetic drugs in hospitalized patients with diabetes mellitus

BACKGROUND

Diabetes mellitus (DM) increases mortality and morbidity in patients with coronavirus disease (COVID-19). In this study, it was aimed to assess factors influencing on COVID-19 pneumonia in hospitalized patients with diabetes and association with oral anti-diabetic drugs.

MATERIALS AND METHODS

This cross-sectional study included 432 patients with type 2 diabetes mellitus diagnosed with COVID-19. Data regarding clinical characteristics, demographic characteristics, intensive care unit (ICU) rate in patients admitted to ICU, laboratory results on day 1 and 7, thoracic computed tomography (CT) findings and oral anti-diabetic drugs used were extracted from medical records. In all patients, 75-days mortality was recorded. Data were assessed independently.

RESULTS

There was pneumonia in 386 (89.4%) of 432 patients with diabetes. The risk for pneumonia was markedly higher in patients on DPP-4 inhibitors; however, there was no significant among other oral anti-diabetic groups and subgroups. In addition, elevated CRP was linked to the increased risk for pneumonia. Only patients in the pneumonia group had SGLT-2 inhibitor use. During follow-up, 91 patients died. In Cox regression analysis, low Glasgow Coma Scale score, and increased lactate dehydrogenase levels were identified as significant independent risk factors for mortality.

CONCLUSION

The study indicated that DPP-4 inhibitor used and elevated CRP level were associated with pneumonia development. Only patients in the pneumonia group had SGLT-2 inhibitor use. No oral anti-diabetics was found to be associated with COVID-19 related death.

Toxicology of Medications for Diabetes Mellitus

Medications used to treat diabetes mellitus are heterogeneous, with widely differing safety profiles in therapeutic use and in overdose. Insulin overdose may produce severe and prolonged hypoglycemia. Sulfonylurea poisoning should be treated with octreotide, sparing intravenous dextrose where possible. Acute metformin overdose may lead to life-threatening acidosis with elevated lactate concentrations, which may require hemodialysis. Glucagon-like peptide 1 agonists and dipeptidyl peptidase 4 inhibitors are benign in overdose in diabetic patients but may produce profound hypoglycemia in nondiabetic patients. Euglycemic diabetic ketoacidosis may develop in critically ill patients taking sodium-glucose co-transporter 2 inhibitors.

DPP-IV Inhibitor-Associated Angioedema in Patient With Known History of ACE Inhibitor Angioedema

The patient is a 69-year-old male with a past medical history of intellectual disability, hypertension, type 2 diabetes mellitus, and angiotensin-converting enzyme (ACE) inhibitor–associated angioedema who presented to the emergency department with difficulty breathing. On physical examination, the patient had significant facial edema. Nasal fiber-optic visualization revealed extensive airway edema involving the supraglottic region and the arytenoids. The patient was successfully intubated through the collective teamwork of ENT, anesthesia, and critical care teams. He was managed in the intensive care unit until recovery. Workup for markers for allergic causes of angioedema were within normal limits. Further investigation revealed that symptoms developed following the initiation of a dipeptidyl peptidase 4 (DPP-IV) inhibitor. The angiotensin-converting enzyme and DPP-IV play a significant role in the metabolism of bradykinin and substance P to their inactive metabolites. The complex interplay between the enzymes in the high-molecular-weight kininogen (HWMK) system may increase the risk of angioedema in patients with a known history of ACE inhibitor–associated angioedema when placed on a DPP-IV inhibitor. This case report highlights the pathophysiology involved.

Drug-Induced Cough

Since the recognition of angiotensin-converting enzyme inhibitors (ACEIs)-induced cough, drug has been considered as a potential cause of chronic cough. This review presents recent knowledge on drug-induced coughs in patients with chronic cough. The focus is placed on ACEIs, for which there are a multitude of studies documenting their associations with cough. Additional drugs are discussed for which there are reports of cough as a side effect of treatment, and the potential mechanisms of these effects are discussed.

Dipeptidyl peptidase-4 inhibitors and the risks of autoimmune diseases in type 2 diabetes mellitus patients in Taiwan: a nationwide population-based cohort study

AIMS

Dipeptidyl peptidase-4, a transmembrane glycoprotein expressed in various cell types, serves as a co-stimulator molecule to influence immune response. This study aimed to investigate associations between DPP-4 inhibitors and risk of autoimmune disorders in patients with type 2 diabetes mellitus in Taiwan.

METHODS

This retrospective cohort study used the nationwide data from the diabetes subsection of Taiwan National Health Insurance Research Database between January 1, 2009, and December 31, 2013. Cox proportional hazards models were developed to compare the risk of autoimmune disorders and the subgroup analyses between the DPP-4i and DPP-4i-naïve groups.

RESULTS

A total of 774,198 type 2 diabetic patients were identified. The adjusted HR of the incidence for composite autoimmune disorders in DPP-4i group was 0.56 (95% CI 0.53-0.60; P < 0.001). The subgroup analysis demonstrated that the younger patients (aged 20-40 years: HR 0.47, 95% CI 0.35-0.61; aged 41-60 years: HR 0.50, 95% CI 0.46-0.55; aged 61-80 years: HR 0.63, 95% CI 0.58-0.68, P = 0.0004) and the lesser duration of diabetes diagnosed (0-5 years: HR 0.48, 95% CI 0.44-0.52; 6-10 years: HR 0.48, 95% CI 0.43-0.53; ≧ 10 years: HR 0.86, 95% CI 0.78-0.96, P < 0.0001), the more significant the inverse association of DPP-4 inhibitors with the incidence of composite autoimmune diseases.

CONCLUSIONS

DPP-4 inhibitors are associated with lower risk of autoimmune disorders in type 2 diabetes mellitus patients in Taiwan, especially for the younger patients and the lesser duration of diabetes diagnosed. The significant difference was found between the four types of DPP-4 inhibitors and the risk of autoimmune diseases. This study provides clinicians with useful information regarding the use of DPP-4 inhibitors for treating diabetic patients.

Adverse event profiles of dipeptidyl peptidase-4 inhibitors: data mining of the public version of the FDA adverse event reporting system

BACKGROUND

To describe and analyze the patterns of adverse events associated with dipeptidyl peptidase-4 inhibitors (DPP-4is) (sitagliptin, saxagliptin, linagliptin, vildagliptin, and alogliptin) from the FDA Adverse Event Reporting System (FAERS) and to highlight areas of safety concerns.

METHODS

Adverse events spontaneously submitted to the FAERS between 2004 Q1 to 2019 Q2 were included. The online tool OpenVigil 2.1 was used to query the database. The research relied on definitions of preferred terms (PTs) specified by the Medical Dictionary for Regulatory Activities (MedDRA) and the standardized MedDRA Queries (SMQ). The reporting odds ratio (ROR), with 95% confidence intervals (CIs) was calculated for disproportionality analysis.

RESULTS

Over 16 years, a total of 9706 adverse event reports were identified. Alogliptin was excluded from further analysis due to insufficient sample size. Compared with the non-insulin antidiabetic drugs, the four DPP-4is were all disproportionately associated with four SMQs: "gastrointestinal nonspecific inflammation and dysfunctional conditions," "hypersensitivity," "severe cutaneous adverse reactions," and "noninfectious diarrhoea". As for PT level analyses, DPP-4is are associated with higher reporting of the gastrointestinal tract, pancreas, malignancies, infection, musculoskeletal disorders, general disorders, hypersensitivity, and skin AEs.

CONCLUSIONS

Data mining of the FAERS is useful for examining DPP-4 inhibitors-associated adverse events. The findings of the present study are compatible with clinical experience, and it provides valuable information to decision-makers and healthcare providers in clinical practice.

Sea Buckthorn and Grape Antioxidant Effects in Hyperlipidemic Rats: Relationship with the Atorvastatin Therapy

Background

Medications to reduce oxidative stress are preventing cellular damage associated with hyperlipidemia. In this regard, statins (e.g., atorvastatin) act primarily by decrease in low-density lipoprotein-c but, in the last decade, hepatotoxicity, associated with liver injuries in the next months after treatments' initiation, was reported. In this case, associated phytotherapy can be a solution.

Purpose

To investigate the antioxidant potential and response to free radicals, in the case of hyperlipidemic rats treated with atorvastatin. Sea buckthorn (Hippophae rhamnoides) and a grape extract (antioxivita) efficiency in the oxidative stress were investigated, also being ascertained the rats' organs cytoarchitecture.

Methods

Eighty-four hyperlipidemic Wistar rats were divided into seven groups and orally treated as follows: ATS, atorvastatin (20 mg/kg·bw); ATS + Hr, atorvastatin + H. rhamnoides; ATS + Aox, atorvastatin + grape extract; Hr, H. rhamnoides; and Aox, grape extract (both as 100 mg/kg·bw). HFD and Control received high fat diet and normal fodder only. After two and six months, respectively, rats were euthanized and the heart, liver, and kidneys were gathered. The tissue samples were prepared by homogenization of 0.5 g tissue, in ethanol, kept for 48 hours at 4°C–10°C and then filtered, in order to assess organs' cytoarchitecture and the TAC's values (by using cupric ion reducing antioxidant capacity (CUPRAC) assay). The test tubes were incubated, at room temperature, for 30 minutes, and then analyzed using a spectrophotometer at 450–650 nm.

Results

The statistics (ANOVA) revealed that sea buckthorn diminished notably (p < 0.001) the oxidative stress in the heart, liver, and kidney. After six months, the TAC's reduced levels for the heart were significant (p < 0.001) in ATS + Aox. In the case of histology, the liver's cytoarchitecture in ATS revealed abnormal cytoarchitecture. In ATS + Hr, ATS + Aox, Hr, and Aox, cell regeneration improved in different stages, especially for ATS + Hr and ATS + Aox, in comparison with HFD, which exhibited fat degeneration. Kidney's cytoarchitecture revealed cellular healing, especially in ATS + Hr and ATS + Aox.

Odds of Acute Kidney Injury in Patients Receiving Dipeptidyl Peptidase 4 Inhibitors: A National Cohort Study Within the Department of Veterans Affairs

Preclinical and clinical data of dipeptidyl peptidase 4 (DPP-4) inhibitors have demonstrated discordant data regarding acute kidney injury (AKI). Therefore, we aimed to evaluate the association between DPP-4 use and AKI. This cohort study utilized data from the Department of Veterans Affairs evaluating patients diagnosed with type 2 (T2) diabetes with a DPP-4 inhibitor and compared with nondiabetic and diabetic patients. The primary end point is the development of AKI, and statistical analyses were performed to examine the association. DPP-4 use is associated with a lower odds of AKI compared with diabetics (adjusted odds ratio (OR) = 0.39; 95% confidence interval (CI) = 0.32-0.48) and nondiabetics (OR = 0.64; 95% CI = 0.52-0.79). DPP-4 use in patients with T2 diabetes mellitus is associated with lower odds of AKI within 120 days compared with nondiabetic and diabetic controls when adjusting for study covariates.

Cardiovascular risk of sitagliptin in treating patients with type 2 diabetes mellitus

Patients with type 2 diabetes mellitus (T2DM) have a very high risk of cardiovascular related events, and reducing complications is an important evaluation criterion of efficacy and safety of hypoglycemic drugs. Previous studies have shown that the dipeptidyl peptidase-4 (DPP-4) inhibitors (DPP4i), such as sitagliptin, might reduce the incidence of major cardiovascular events (MACEs). However, the safety and efficacy of sitagliptin remains controversial, especially the safety for cardiovascular related events. Here, a systematic review was conducted to assess the cardiovascular safety of sitagliptin in T2DM patients. The literature research dating up to October 2018 was performed in the electronic database. The clinical trials about sitagliptin for T2DM patients were included. Two reviewers independently screened literature according to the inclusion and exclusion criteria. The primary outcome was the MACE, and the secondary outcome was all-cause mortality. Finally, 32 clinical trials composed of 16082 T2DM patients were included in this meta-analysis. The results showed that: there was no significant difference between sitagliptin group and the control group on MACE (odds ratio (OR) = 0.85, 95% confidence intervals (CIs) = 0.63–1.15), myocardial infarction (MI) (OR = 0.66, 95% CI = 0.38–1.16), stroke (OR = 0.83, 95% CI = 0.44–1.54) and mortality (OR = 0.52, 95% CI = 0.26–1.07). These results demonstrated that sitagliptin did not increase the risk of cardiovascular events in patients with T2DM.

The Role of DPP-4 Inhibitors in the Treatment Algorithm of Type 2 Diabetes Mellitus: When to Select, What to Expect

Type 2 diabetes mellitus is a growing global public health problem, the prevalence of which is projected to increase in the succeeding decades. It is potentially associated with many complications, affecting multiple organs and causing a huge burden to the society. Due to its multi-factorial pathophysiology, its treatment is varied and based upon a multitude of pharmacologic agents aiming to tackle the many aspects of the disease pathophysiology (increasing insulin availability [either through direct insulin administration or through agents that promote insulin secretion], improving sensitivity to insulin, delaying the delivery and absorption of carbohydrates from the gastrointestinal tract, or increasing urinary glucose excretion). DPP-4 (dipeptidyl peptidase-4) inhibitors (or “gliptins”) represent a class of oral anti-hyperglycemic agents that inhibit the enzyme DPP-4, thus augmenting the biological activity of the “incretin” hormones (glucagon-like peptide-1 [GLP-1] and glucose-dependent insulinotropic polypeptide [GIP]) and restoring many of the pathophysiological problems of diabetes. They have already been used over more than a decade in the treatment of the disease. The current manuscript will review the mechanism of action, therapeutic utility, and the role of DPP-4 inhibitors for the treatment of type 2 diabetes mellitus.

DPP-4 INHIBITORS INCREASE THE INCIDENCE OF ARTHRITIS/ARTHRALGIA BUT DO NOT AFFECT AUTOIMMUNITY

AIMS

In August 2015, FDA published a black box declaring that DPP-4 inhibitors may cause severe joint pains. The impact on autoimmunity marker positivity of these drugs has not been comprehensively evaluated. We compared the incidence of arthritis/arthralgia in patients with T2DM who were using DPP-4 inhibitors and patients who were not using.

METHODS

A number of 93 DPP-4 inhibitor users and 107 non-users were included into the study. Arthritis/arthralgia were found in 41 of 93 (44.1%) DPP-4 inhibitor users and in 19 of 107 (17.8%) non-users (p<0.05).

RESULTS

No inflammatory rheumatological condition was identified in 27 of 41 (65.9%) patients in DPP-4 inhibitor user group as well as in 13 of 19 (68.4%) patients in non-user group (p>0.05). After adjusting for gender the incidence for arthritis/arthralgia was significantly increased in the DPP-4 inhibitor user group (p value for any DPP-inhibitor <0.05). There was 3.77 times increased risk for arthritis/arthralgia in the DPP-4 inhibitor using group (p value= 0.001) and this risk increases 2.43 times for each year of DPP-4 inhibitor usage.

CONCLUSIONS

Arthritis/arthralgia were more common among T2DM patients who were using DPP-4 inhibitors compared to non-users, but the seropositivity did not differ between DPP-4 inhibitor users and non-users.

A Review on Cardiovascular Outcome Studies of Dipeptidyl Peptidase-4 Inhibitors

The U.S. Food and Drug Administration issued a guidance for pharmaceutical industry defining preapproval and postapproval requirements for the demonstration of cardiovascular (CV) safety for all new medications developed for glycemic management in type 2 diabetes. However, results published from the studies of dipeptidyl peptidase-4 (DPP-4) inhibitors are conflicting with regard to different CV endpoints. Upcoming CV outcome studies perhaps will be able to provide additional insights related to diabetes management and help to provide the answers to some of these concerns. This article provides a brief overview regarding how various CV safety evidence of DPP-4 inhibitor evolved over time that highlights possible implication in clinical practice and translates them into effective diabetes management.

Evaluation of pharmacokinetic and pharmacodynamic parameters following single dose of sitagliptin in healthy Indian males

PURPOSE

Sitagliptin, a dipeptidyl peptidase (DPP)-IV inhibitor approved for the treatment of type 2 diabetes, is reported to be more efficacious in Indian patients than non-Indian patient population. The objective of the study was to evaluate pharmacokinetic and pharmacodynamic (PK/PD) parameters of single-dose sitagliptin 100 mg (Januvia) in healthy Indian male participants.

METHOD

In a randomised, single-dose, open-label, three-treatment, three-period, three-sequence, crossover bioavailability study, 18 healthy male participants received single-dose of sitagliptin under fasted and fed conditions. PK parameters (C_max, T_max, AUC_0-∞ and t_1/2) were determined using Phoenix WinNonlin software. PD parameters [DPP-IV inhibition, active glucagon-like peptide-1 (GLP-1) and insulin] were determined using established methods.

RESULTS

PK parameters expressed in mean (SD) were C_max 491.7 (135.9) ng/mL; AUC_0-∞ 4256.1 (509.9) ng· hr/mL, T_max 2.9 (1.0) hr and t_1/2 10.4 (3.0) hr. The weighted average (WA) plasma DPP-4 inhibition over 24 h was 89.6% and WA of plasma active GLP-1 over 2 h after standardised meal (geometric mean ratio) was 11.1 (9.9) pM/L which is two- to- four fold higher compared to that reported in other populations. The mean average (SD) AUC of plasma insulin over 2 h of standardised meal was 47.9 (24.9) μIU/mL.

CONCLUSION

Although, there are differences in pharmacokinetic parameters, no clinically meaningful differences were observed with respect to DPP-IV inhibition between Indian and non-Indian population.

Pharmacotherapy of type 2 diabetes: An update

Type 2 diabetes (T2DM) is a leading cause of morbidity and mortality worldwide and a major economic burden. The prevalence of T2DM is rising, suggesting more effective prevention and treatment strategies are necessary. The aim of this narrative review is to summarize the pharmacologic treatment options available for patients with T2DM. Each therapeutic class is presented in detail, outlining medication effects, side effects, glycemic control, effect on weight, indications and contraindications, and use in selected populations (heart failure, renal insufficiency, obesity and the elderly). We also present representative cost for each antidiabetic category. Then, we provide an individualized guide for initiation and intensification of treatment and discuss the considerations and rationale for an individualized glycemic goal.

Treatment Discontinuation and Clinical Events in Type 2 Diabetes Patients Treated with Dipeptidyl Peptidase-4 Inhibitors or NPH Insulin as Third-Line Therapy

OBJECTIVE

To compare dipeptidyl peptidase-4 (DPP-4) inhibitors with neutral protamine Hagedorn (NPH) insulin, in terms of effectiveness and safety for the management of patients with type 2 diabetes mellitus (DM2) not controlled on metformin and sulfonylureas.

METHODS

A retrospective cohort study of individuals with DM2 newly dispensed with either DPP-4 inhibitors or NPH as third-line therapy, after metformin and sulfonylurea. Treatment discontinuation, macrovascular outcomes, and hypoglycemia were compared using multivariable Cox regression models, adjusted for sex, age, year of cohort entry, place of residence, hypertension, past history of hypoglycemia, diabetic ketoacidosis, comorbidities, and number of visits to emergency departments, outpatient physician, and hospitalizations.

RESULTS

Treatment discontinuation and hypoglycemia occurred more frequently with NPH than with DPP-4 inhibitor users. In the adjusted Cox model, the use of NPH compared to that of DPP-4 inhibitors was associated with a higher risk of discontinuation (HR: 1.33; 95% CI 1.27-1.40) and hypoglycemia (HR: 2.98; 95% CI 2.72-3.28). Risk of cardiovascular events was similar across groups.

CONCLUSIONS

This real-world analysis suggests that DM2 patients initiating third-line therapy with NPH have poorer control of diabetes when compared to DPP-4 inhibitor initiators.

Effect of Long-term Incretin-Based Therapies on Ischemic Heart Diseases in Patients with Type 2 Diabetes Mellitus: A Network Meta-analysis

Patients with type 2 diabetes mellitus (T2DM) experience many cardiovascular complications. Several studies have demonstrated the cardioprotective effects of incretin-based therapies; however, there are few studies on the effects of long-term incretin-based therapies on cardiovascular events. Therefore, the present study conducted a systematic review and network meta-analysis to evaluate the effects of long-term incretin-based therapies on ischaemic diseases. We searched PubMed, CENTRAL, and Clinicaltrial.gov to retrieve randomised control trials reported until December 2016 and enrolled only RCTs with more than a 1-year follow-up. The network meta-analysis was performed using R Software with a GeMTC package. A total of 40 trials were included. Dipeptidyl peptidase 4 inhibitors and glucagon-like peptide-1 agonists were associated with a lower risk of myocardial infarction (MI) than were sulfonylureas (odds ratio [95% credible interval] 0.41 [0.24–0.71] and 0.48 [0.27–0.91], respectively). These results suggested that patients with T2DM receiving long-term incretin-based therapies have a lower risk of MI than do those receiving sulfonylurea-based therapy. These findings highlight the risks of cardiovascular events in patients who receive long-term incretin-based therapies, and may provide evidence for the selection of antidiabetic therapy in the future.

Gastrointestinal symptom prevalence depends on disease duration and gastrointestinal region in type 2 diabetes mellitus

AIM

To unravel relationships between gastrointestinal (GI) symptoms impairing quality of life (QOL) and clinical profiles of diabetes mellitus (DM) patients.

METHODS

We enrolled 134 outpatients with type 2 DM. Mean age was 64.7 years, mean body mass index was 24.7 kg/m², mean glycated hemoglobin was 7.1%, and mean DM duration was 13.7 years. GI symptom-related QOL was determined using the Izumo scale, based on five factors, i.e., heartburn, gastralgia, postprandial fullness, constipation and diarrhea. The sum of scores obtained for the three questions in each domain was calculated, and subjects with a score of 5 or higher were considered to be symptomatic with impaired QOL. JMP Clinical version 5.0 was used for all statistical analyses.

RESULTS

Lower abdominal symptoms were found to be more frequent than those affecting the upper abdomen. Diabetic duration and medications showed associations with GI symptoms. We identified differences in peak prevalences of the five symptoms. Gastralgia (P = 0.02 vs 10-14 years) and total GI symptoms (P = 0.01 and P = 0.02 vs 5-9 years and 10-14 years, respectively) peaked at a diabetes duration of 15-19 years. Heartburn (P = 0.004) and postprandial fullness (P = 0.03) tended to increase with disease duration. Constipation and diarrhea showed bimodal peaks, with the first early and the second late (e.g., P = 0.03 at 15-19 years vs 10-14 years for diarrhea) in the disease course. Finally, GI symptoms showed clustering that reflected the region of the GI tract affected, i.e., constipation and diarrhea had similar frequencies (P < 0.0001).

CONCLUSION

Our study highlights the importance of questioning patients about QOL impairment due to abdominal symptoms, especially in the early and the late periods of diabetes.

Gastrointestinal Adverse Events of Dipeptidyl Peptidase 4 Inhibitors in Type 2 Diabetes: A Systematic Review and Network Meta-analysis

PURPOSE

The purpose of this study was to systematically evaluate the effect of dipeptidyl peptidase 4 inhibitors on gastrointestinal adverse events in patients with type 2 diabetes.

METHODS

MEDLINE, Embase, the Cochrane Library, and ClinicalTrials.gov were searched from inception through April 28, 2016. Randomized controlled trials that compared dipeptidyl peptidase 4 inhibitor-based therapies with placebo and other hypoglycemic agents in type 2 diabetes were included. The duration of studies was at least 4 weeks.

FINDINGS

A total of 165 randomized controlled trials and 122,072 patients were included in the study. Dipeptidyl peptidase 4 inhibitors did not increase the incidence of gastrointestinal adverse events after the treatment with alogliptin (odds ratio [OR] = 0.83; 95% CI, 0.59-1.15), linagliptin (OR = 1.11; 95% CI, 0.92-1.35), saxagliptin (OR = 0.96; 95% CI, 0.80-1.15), sitagliptin (OR = 0.95; 95% CI, 0.64-1.14), teneligliptin (OR = 1.50; 95% CI, 0.81-2.77), and vildagliptin (OR = 0.80; 95% CI, 0.63-1.01) compared with placebo. Compared with glucagon-like peptide 1 receptor agonists, dipeptidyl peptidase 4 inhibitors significantly decreased the incidence of gastrointestinal adverse events with alogliptin (OR = 0.26; 95% CI, 0.15-0.44), linagliptin (OR = 0.43; 95% CI, 0.25-0.74), saxagliptin (OR = 0.28; 95% CI, 0.17-0.46), sitagliptin (OR = 0.24; 95% CI, 0.17-0.35), and vildagliptin (OR = 0.27; 95% CI, 0.18-0.41). Dipeptidyl peptidase 4 inhibitors were not associated with an increased risk of gastrointestinal adverse events relative to metformin and α-glucosidase inhibitors, respectively.

IMPLICATIONS

The network meta-analysis found that compared with glucagon-like peptide 1 receptor agonists, metformin, and α-glucosidase inhibitor, dipeptidyl peptidase 4 inhibitors are associated with a lower incidence of gastrointestinal adverse events.

Combining the G-protein-coupled receptor 40 agonist fasiglifam with sitagliptin improves glycaemic control in patients with type 2 diabetes with or without metformin: A randomized, 12-week trial

AIMS

To evaluate the efficacy and safety of fasiglifam, an orally active G-protein-coupled receptor 40 agonist, in combination with the dipeptidyl peptidase-4 inhibitor sitagliptin, in patients with type 2 diabetes inadequately controlled with diet/exercise (± metformin).

MATERIALS AND METHODS

In this randomized, double-blind, phase II study, 368 patients received once-daily placebo, sitagliptin 100 mg, fasiglifam 25 or 50 mg, or the combination of sitagliptin 100 mg plus fasiglifam 25 or 50 mg. The primary endpoint was change from baseline glycated haemoglobin (HbA1c) at 12 weeks; a key secondary endpoint was change in fasting plasma glucose (FPG).

RESULTS

The fasiglifam 25 and 50 mg combination regimens produced significantly greater HbA1c reductions than sitagliptin (treatment differences of -0.45% and -0.61%; P < .01, respectively) or respective doses of fasiglifam monotherapy (-0.43% and -0.48%; P < .01) and significantly greater FPG reductions than sitagliptin (-1.1 mmol/L for both combination regimens; P < .01). Improved glycaemic control occurred by week 1 for FPG and week 4 for HbA1c in all groups. Hypoglycaemia rates were low (≤3.3%) and similar across treatments. Liver enzymes >3 × upper limit of normal occurred in four patients (fasiglifam 25 mg, n = 1; fasiglifam 50 mg, n = 2; 1 fasiglifam/sitagliptin 50/100 mg, n = 1).

CONCLUSIONS

Combination of fasiglifam and sitagliptin provided significant additional effects on glycaemic control, with hypoglycaemia rates similar to placebo with or without metformin. This study provides supportive clinical evidence for the complementary mechanism of actions of this GPR40 agonist and DPP-4 inhibitor.

Dipeptidyl peptidase-4 inhibitors and risk of arthralgia: A systematic review and meta-analysis

BACKGROUND

The US Food and Drug Administration has warned that treatment with dipeptidyl peptidase (DPP)-4 inhibitors may promote serious arthralgia. However, the clinical evidence for this is relatively lacking.

OBJECTIVE

For this reason, a systematic review and meta-analysis of randomized controlled trials (RCTs) were carried out to determine the relationship between DPP-4 inhibitors and risk of arthralgia, and also to investigate any potential risk factors.

METHODS

An extensive electronic search for RCTs comparing DPP-4 inhibitors with any comparators was performed up to July 2016. Outcomes of interest were overall and serious arthralgia. Summary risk ratios (RRs) with 95% confidence intervals (CIs) were calculated.

RESULTS

A total of 67 RCTs (involving 79,110 patients) was ultimately included. Pooled results showed that DPP-4 inhibitors were associated with a slightly but significantly increased risk of overall arthralgia (RR: 1.13, 95% CI: 1.04-1.22; P=0.003) and a non-significant increased risk of serious arthralgia (RR: 1.44, 95% CI: 0.83-2.51; P=0.20). Also, subgroup analyses showed that add-on/combination therapy and longer diabetes duration (>5years) were possible factors associated with the increased risk of overall arthralgia.

CONCLUSION

These findings suggest that DPP-4 inhibitors can increase the risk of arthralgia. Thus, the benefits of glycaemic control must be weighed against the risk of arthralgia when prescribing DPP-4 inhibitors. Further studies are now needed to identify and confirm these risk factors.

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 Dipeptidyl-Peptidase IV Inhibitors: A Meta-Analysis of Placebo-Controlled Randomized Trials

BACKGROUND

Large randomized trials have shown conflicting evidence regarding the cardiovascular safety of dipeptidyl-peptidase 4 (DPP-4) inhibitors. Systematic reviews have been limited by incomplete data and inclusion of observational studies. This study aimed to systematically evaluate the cardiovascular safety of DPP-4 inhibitors in patients with type 2 diabetes.

METHODS

Electronic databases were searched for randomized trials that compared DPP-4 inhibitors versus placebo and reported cardiovascular outcomes. The main outcome assessed in this analysis was heart failure. Other outcomes included all-cause mortality, cardiovascular mortality, myocardial infarction, and ischemic stroke. Summary odds ratios (ORs) were primarily constructed using Peto's model.

RESULTS

A total of 90 trials with 66,730 patients were included. Compared with placebo, DPP-4 inhibitors were associated with a non-significant increased risk of heart failure [OR 1.11, 95% confidence interval (CI) 0.99-1.25, P = 0.07] at a mean of 108 weeks. The risk of all-cause mortality (OR 1.03, 95% CI 0.94-1.12, P = 0.53), cardiovascular mortality (OR 1.02, 95% CI 0.92-1.14, P = 0.72), myocardial infarction (OR 0.98, 95% CI 0.88-1.09, P = 0.69), and ischemic stroke (OR 0.99, 95% CI 0.85-1.15, P = 0.92) was similar between both groups.

CONCLUSION

In patients with type 2 diabetes, the safety profile of DPP-4 inhibitors is similar to placebo. As a class, there is only weak evidence for an increased risk of heart failure.

Consensus Statement on Dose Modifications of Antidiabetic Agents in Patients with Hepatic Impairment

Liver disease is an important cause of mortality in type 2 diabetes mellitus (T2DM). It is estimated that diabetes is the most common cause of liver disease in the United States. Virtually, entire spectrum of liver disease is seen in T2DM including abnormal liver enzymes, nonalcoholic fatty liver disease, cirrhosis, hepatocellular carcinoma, and acute liver failure. The treatment of diabetes mellitus (DM) in cirrhotic patients has particular challenges as follows: (1) about half the patients have malnutrition; (2) patients already have advanced liver disease when clinical DM is diagnosed; (3) most of the oral antidiabetic agents (ADAs) are metabolized in the liver; (4) patients often have episodes of hypoglycemia. The aim of this consensus group convened during the National Insulin Summit 2015, Puducherry, was to focus on the challenges with glycemic management, with particular emphasis to safety of ADAs across stages of liver dysfunction. Published literature, product labels, and major clinical guidelines were reviewed and summarized. The drug classes included are biguanides (metformin), the second- or third-generation sulfonylureas, alpha-glucosidase inhibitors, thiazolidinediones, dipeptidyl peptidase-4 inhibitors, sodium-glucose co-transporter 2 inhibitors, glucagon-like peptide-1 receptor agonists, and currently available insulins. Consensus recommendations have been drafted for glycemic targets and dose modifications of all ADAs. These can aid clinicians in managing patients with diabetes and liver disease.

Expression of GLP-1 receptor and CD26 in human thyroid C-cells: The association of thyroid C-cell tumorigenesis with incretin-based medicine

Recent reports have demonstrated that long-term and high dosage treatments with incretin-based medicine, such as hormone glucagon-like peptide-1 (GLP-1) may induce thyroid C-cell pathological changes in rodents, rather than in humans. Doubts regarding the tumorigenic potential of GLP-1 analogues in human thyroid C-cells remain. The present study aimed to determine the expression levels of GLP-1 receptor (GLP-1R) and cluster of differentiation 26 (CD26) in the C-cells of thyroid tissues from non-neoplastic, medullary carcinoma and hyperplasia subjects, and to explore the potential clinical significance. The following cases were analyzed: Medullary thyroid carcinoma (n=62, including 59 paraffin-embedded samples and 3 fresh frozen samples), C-cell hyperplasia (n=20, paraffin-embedded samples) and non-neoplastic thyroid tissue samples (n=7, paraffin-embedded samples). GLP-1R and CD26 expression was detected using immunohistochemical staining and western blotting. There were significant differences in the expression levels of the two markers between medullary thyroid carcinoma and C-cell hyperplasia, in addition to between medullary thyroid carcinoma and non-neoplastic thyroid tissue following immunohistochemical staining. Similar significant differences in the expression of GLP-1R and CD26 were detected using western blot analysis in the medullary thyroid carcinoma compared with non-neoplastic thyroid tissue sectioned from the aforementioned fresh frozen samples. There was a significant negative correlation between GLP-1R and CD26 expression. In addition, the present data indicated that GLP-1R expression was associated with the age of the patients with medullary thyroid carcinoma. These results suggested that GLP-1R and CD26 may be closely associated with the development of thyroid C-cell hyperplasia and medullary thyroid carcinoma, and indicated the importance of being aware of the side effects of incretin medicine.

Dipeptidyl Peptidase-4 Inhibitor–Associated Risk of Bleeding: An Evaluation of Reported Adverse Events

Background: Dipeptidyl peptidase-4 (DPP-4) inhibitors improve glycemic control, and sitagliptin has been associated with a reduction in cardiovascular events. In vivo data suggest reduced platelet activation, and aggregation may play a role, and therefore, increased bleeding risk is possible. Objective: Comparatively assess bleeding risks associated with DPP-4 inhibitors against standard treatment. Methods: Exploratory analyses of adverse event reports (AERs) from the US Food and Drug Administration Adverse Event Reporting System (FAERS) database (2004-2012 periods) were conducted. DPP-4 inhibitor–related bleeding was assessed with metformin as negative control, and aspirin, clopidogrel, and prasugrel illustrated positive comparators. Reporting odds ratios (RORs) and 95% CIs were calculated as a measure of disproportionality of reporting, and RORs were compared across drugs with the Breslow-Day statistics. Results: From 2004 to 2012, 36 298, 4288, and 1202 AERs were found for sitagliptin, saxagliptin, and linagliptin, respectively, with 863, 102, and 14 bleeding complications. The relative reporting rate was not elevated with any DPP-4 inhibitor (sitagliptin: ROR = 0.71, 95% CI = 0.67-0.76; saxagliptin: ROR = 0.72, 95% CI = 0.59-0.87; linagliptin: ROR = 0.35, 95% CI = 0.20-0.59) or with metformin (ROR = 0.77; 95% CI = 0.75-0.78). Sitagliptin showed relatively higher reporting as compared with linagliptin ( P = 0.006) but not with saxagliptin ( P = 0.98). As positive references, antiplatelet drugs demonstrated relatively higher reporting compared with metformin (aspirin: ROR = 1.50, 95% CI = 1.48-1.51; clopidogrel: ROR = 2.28, 95% CI = 2.23-2.33; prasugrel: ROR = 5.09, 95% CI = 4.57-5.67). Conclusion: DPP-4 inhibitors were not associated with an undue increase in bleeding AERs in the FAERS database.

Mechanisms of Cardiovascular Injury in Type 2 Diabetes and Potential Effects of Dipeptidyl Peptidase-4 Inhibition

BACKGROUND

Cardiovascular (CV) disease is the major cause of mortality and morbidity in patients with type 2 diabetes mellitus (T2DM). The pathogenesis of CV disease in T2DM is complex and multifactorial and involves direct and indirect injury to the vasculature and heart. The impact of intensive glucose-lowering therapy with antihyperglycemic agents on CV outcomes is not clear, and questions remain as to which glucose-lowering agents may be beneficial to CV health in patients with T2DM.

PURPOSE

This review discusses findings regarding the known mechanisms of CV injury in T2DM and current knowledge regarding the potential cardioprotective effects of dipeptidyl peptidase-4 (DPP-4) inhibitors.

CONCLUSIONS

Dipeptidyl peptidase-4 inhibitors are relatively new antihyperglycemic agents. Their main mechanism of action is to inhibit the degradation of the incretin hormones glucagon-like peptide-1 and glucose-dependent insulinotropic peptide by DPP-4. By increasing levels of glucagon-like peptide-1, glucose-dependent insulin secretion is enhanced, glucagon secretion is suppressed, and the rate of gastric emptying is decreased. Dipeptidyl peptidase-4 also degrades other substances that are important in the regulation of CV function and inflammation. Animal studies, small observational studies in humans, and analyses of clinical trial data suggest that DPP-4 inhibitors may have beneficial CV effects. Recent prospectively designed CV outcomes trials with saxagliptin and alogliptin in patients with T2DM and high CV risk presented evidence that these DPP-4 inhibitors neither increased nor decreased adverse CV outcomes in this select patient population.

CLINICAL IMPLICATIONS

Dipeptidyl peptidase-4 inhibitors are promising therapies for the treatment of T2DM. Able to improve glycemic control without the risk of weight gain or hypoglycemia, they provide a safe alternative to sulfonylureas and are an effective adjunct to metformin. To date, this class of drugs seems to be at least neutral in terms of CV effects. Time will tell if these findings translate into a benefit for our patients.

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.

Dipeptidyl Peptidase (DPP)-4 Inhibitor-Induced Arthritis/Arthralgia: A Review of Clinical Cases

Dipeptidyl peptidase (DPP)-4 inhibitors are a class of oral drugs used for the treatment of type 2 diabetes mellitus (T2DM). The pharmacological inhibition of DPP-4 seems to also induce adverse events related to cytokine-induced inflammation. Recently, several clinical cases regarding the association of DPP-4 inhibitors and the onset of arthritis/arthralgia have been reported in the literature. Various mechanisms could be responsible for DPP-4 inhibitor-induced arthritis/arthralgia, and the increase of cytokines, chemokines, matrix metalloproteinases (MMPs) and genetic factors plays an important role. The US FDA published a safety announcement regarding the entire drug class, encouraging healthcare professionals and patients to pay attention to the occurrence of arthralgia during treatment with DPP-4 inhibitors; arthralgia could be assessed as a class adverse drug event for DPP-4 inhibitors. To summarize the evidence on the correlation between DPP-4 inhibitors and arthritis/arthralgia, and to explain the measures taken by the FDA with regard to arthralgia risk, we performed a literature review of recent evidence concerning this association. This review shows the necessity of other studies to better define the association between DPP-4 inhibitors and arthritis/arthralgia.

Regulation of Chemokine Activity - A Focus on the Role of Dipeptidyl Peptidase IV/CD26

Chemokines are small, chemotactic proteins that play a crucial role in leukocyte migration and are, therefore, essential for proper functioning of the immune system. Chemokines exert their chemotactic effect by activation of chemokine receptors, which are G protein-coupled receptors (GPCRs), and interaction with glycosaminoglycans (GAGs). Furthermore, the exact chemokine function is modulated at the level of posttranslational modifications. Among the different types of posttranslational modifications that were found to occur in vitro and in vivo, i.e., proteolysis, citrullination, glycosylation, and nitration, NH₂-terminal proteolysis of chemokines has been described most intensively. Since the NH₂-terminal chemokine domain mediates receptor interaction, NH₂-terminal modification by limited proteolysis or amino acid side chain modification can drastically affect their biological activity. An enzyme that has been shown to provoke NH₂-terminal proteolysis of various chemokines is dipeptidyl peptidase IV or CD26. This multifunctional protein is a serine protease that preferably cleaves dipeptides from the NH₂-terminal region of peptides and proteins with a proline or alanine residue in the penultimate position. Various chemokines possess such a proline or alanine residue, and CD26-truncated forms of these chemokines have been identified in cell culture supernatant as well as in body fluids. The effects of CD26-mediated proteolysis in the context of chemokines turned out to be highly complex. Depending on the chemokine ligand, loss of these two NH₂-terminal amino acids can result in either an increased or a decreased biological activity, enhanced receptor specificity, inactivation of the chemokine ligand, or generation of receptor antagonists. Since chemokines direct leukocyte migration in homeostatic as well as pathophysiologic conditions, CD26-mediated proteolytic processing of these chemotactic proteins may have significant consequences for appropriate functioning of the immune system. After introducing the chemokine family together with the GPCRs and GAGs, as main interaction partners of chemokines, and discussing the different forms of posttranslational modifications, this review will focus on the intriguing relationship of chemokines with the serine protease CD26.

Genitourinary infections in diabetic patients in the new era of diabetes therapy with sodium-glucose cotransporter-2 inhibitors

AIMS

To review prevalence and significance of urinary tract (UTI) and genital infections (GI) in diabetes and the effects of sodium glucose cotransporter 2 (SGLT-2) inhibitors on these complications.

DATA SYNTHESIS

The prevalence of asymptomatic bacteriuria (ASB) is 2-3 times higher in diabetic than in non-diabetic women. The treatment of ASB has no impact on the development of UTIs and/or a decline in renal function. Therefore, there is no indication for screening for and/or treatment of ASB. The incidence of UTI is higher and frequently complicated in diabetic patients, particularly in those with longer duration of disease and of older age. There is no consistent evidence of an association between A1c levels, glycosuria and the risk of ASB and/or UTIs. Diabetes is a known risk factor for Candida colonization and GI, and a poor glycemic control is associated with a higher risk. While patients treated with SGLT-2 inhibitors may have a non-significant increased risk of UTI, they have a clearly increased risk of GI; most of these infections are mild, easy to treat, and the rate of recurrence is low.

CONCLUSION

Diabetic patients are at high risk of UTIs and of GI. Only GI are associated with poor glycemic control. Although patients treated with SGLT-2 inhibitors have an increased 3-5 fold risk of GI, proper medical education can reduce this risk.

Impact of baseline body mass index status on glucose lowering and weight change during sitagliptin treatment for type 2 diabetics

AIMS

This study was designed to evaluate the efficacy of sitagliptin in Taiwanese diabetic subjects with different baseline BMI status.

METHODS

This was a single-center, hospital-based, retrospective chart review in subjects (n=1874) with type 2 diabetes who received sitagliptin. Subjects were classified into subgroups depending upon their baseline BMI by Taiwan national weight classification: normal (BMI<24kg/m(2)) (n=504), overweight (BMI: 24-27kg/m(2)) (n=615), and obese (BMI⩾27kg/m(2)) (n=755). Changes in HbA1c and weight were evaluated over a 12month treatment period.

RESULTS

For all three groups, the HbA1c levels declined over the first three months by about 8%, and subsequently plateaued for the next nine months. Obese subjects were slower in reducing HbA1c compared with normal and overweight subjects (P<0.05), but at nine months the reduction was similar across groups. Mean body weight increased over the first nine months of sitagliptin therapy in subjects with normal BMI (57.12-58.30kg), but there was no change in mean body weight in the overweight group. After three months the obese groups had significantly greater loss in body weight compared with the normal group.

CONCLUSIONS

Baseline BMI status may influence the reduction of HbA1c levels within the first six months of sitagliptin therapy and affect weight change after three months. Being obese was associated with an initial lag in HbA1c reduction and greater weight loss compared with normal and overweight subjects.

Novel antidiabetic drugs and cardiovascular risk: Primum non nocere

AIMS

Diabetes treatments aim at preventing undesirable metabolic effects of hyperglycemia and at preventing/reducing tissue damage, including cardiovascular (CV) events. For approval, novel diabetes drugs undergo early systematic investigation to assess CV safety. This review provides an updated analysis of the results of recent studies examining novel diabetes medications and CV outcomes.

DATA SYNTHESIS

The new regulatory guidelines enforce adjudication of all CV events when testing novel diabetes drugs. Endpoints of CV mortality, myocardial infarction (MI), stroke and hospitalization for heart failure (HF) were included in the most recent clinical studies on novel antihyperglycemics. These are: the incretin mimetics glucagon-like peptide 1 (GLP-1) receptor agonists (GLP1-RA), the incretin enhancers dipeptidylpeptidase-4 (DPP-4) inhibitors (DPP4-I or gliptins), and the sodium-glucose cotransporter (SGLT2) inhibitors (SGLT2-I or gliflozins). The studies ELIXA and EXAMINE, testing lixisenatide and alogliptin, respectively, revealed non-inferiority versus placebo in terms of CV safety. The SAVOR-TIMI 53 results confirmed overall CV safety of saxagliptin, but raised a warning related to the increase in the risk of hospitalization for HF in the saxagliptin group. Recently, TECOS revealed a particularly favorable CV profile for sitagliptin while EMPA-REG showed a significant CV risk reduction in empagliflozin treated subjects. Ongoing studies will provide additional data on CV safety for other GLP1-RAs, DPP4-I and SGLT2-I.

CONCLUSIONS

Results of safety outcome studies focused on CV events, including HF and mortality for CV causes, are not homogeneous. A critical analysis of these studies may help cardiologists and diabetes specialists to adapt their therapeutic choices to individual patients.

Treatment intensification in patients with inadequate glycemic control on basal insulin: rationale and clinical evidence for the use of short-acting and other glucagon-like peptide-1 receptor agonists

A substantial proportion of patients with type 2 diabetes mellitus do not reach glycemic targets, despite treatment with oral anti-diabetic drugs and basal insulin therapy. Several options exist for treatment intensification beyond basal insulin, and the treatment paradigm is complex. In this review, the options for treatment intensification will be explored, focusing on drug classes that act via the incretin system and paying particular attention to the short-acting glucagon-like peptide-1 receptor agonists exenatide and lixisenatide. Current treatment guidelines will be summarized and discussed. © 2016 The Authors. Diabetes/Metabolism Research and Reviews Published by John Wiley & Sons Ltd.

Association of Sitagliptin with cardiovascular outcome in diabetic patients: a nationwide cohort study

AIMS

Although dipeptidyl peptidase-4 (DPP-4) inhibitor improves glycemic control, the actual cardiovascular outcomes remain unclear. The objective of this cohort study was to thus evaluate the cardiovascular outcome in diabetic patients who received DPP-4 inhibitors (Sitagliptin).

METHODS

A total of 104,756 new diabetic patients were identified from the Taiwan National Health Insurance Research Database during the period from March 1, 2003 to December 31, 2011. Patients who received Sitagliptin therapy were included as exposures, and up to four age- and sex-matched controls were selected by risk-set sampling. Outcomes such as major adverse cardiovascular diseases (CVD) and deaths were assessed. Logistic regression models were applied to estimate the hazard ratios and 95 % CIs between DPP-4 inhibitor use and cardiovascular outcome.

RESULTS

Over a mean of 14 months, the rates of total CVD per 1000 person-months were significantly lower in Sitagliptin users (3.41 vs. 5.17, p < 0.001), whereas other different CVDs (hazard ratio [HR] 0.59; 95 % confidence interval [CI] 0.48-0.72 for coronary heart disease; HR 0.75; 95 % CI 0.59-0.96 for ischemic stroke; HR 0.86; 95 % CI 0.45-1.65 for peripheral artery occlusive disease) and all-cause mortality (HR 0.56; 95 % CI 0.41-0.74]) were also fewer after adjustment for covariates.

CONCLUSIONS

The results showed a favorable outcome of Sitagliptin as a class on lowering CVD incidence in patients with type 2 diabetes.

DPP-4 inhibitors and risk of infections: a meta-analysis of randomized controlled trials

BACKGROUND

To evaluate the risk of infections in the treatment of type 2 diabetes patients with dipeptidyl-peptidase 4 (DPP-4) inhibitors.

METHODS

A literature search was conducted through electronic databases. The inclusion criteria included study duration of no less than 12 weeks developed in type 2 diabetes patients, the use of a randomized control group receiving a DPP-4 inhibitor and the availability of outcome data for infections. Out of 2181 studies, 74 studies were finally included.

RESULTS

The risk of overall infection for DPP-4 inhibitors treatment was comparable to placebo (odds ratio (OR) = 0.97, 95% confidence interval (CI), 0.91 to 1.04, p = 0.40), metformin treatment (OR = 1.22, 95% CI, 0.95 to 1.56, p = 0.12), sulphonylurea treatment (OR = 1.09, 0.93 to 1.29, p = 0.29), thiazolidinedione treatment (OR = 0.86, 95% CI, 0.65 to 1.14, p = 0.29) and alpha glucosidase inhibitor treatment (OR = 1.03, 95% CI, 0.33 to 3.22, p = 0.96). When compared different DPP-4 inhibitors with placebo treatment, risks of infections were comparable for alogliptin, linagliptin, sitagliptin, saxagliptin and vildagliptin. Compared with placebo or active comparator treatment, risks of infection in different systems for DPP-4 inhibitors were all comparable.

CONCLUSIONS

The overall risk of infections of DPP-4 inhibitor was not increased compared with control groups.

Assessment of cardiovascular risk of new drugs for the treatment of diabetes mellitus: risk assessment vs. risk aversion

The Food and Drug Administration issued guidance for evaluating the cardiovascular risk of new diabetes mellitus drugs in 2008. Accumulating evidence from several completed trials conducted within this framework raises questions as to whether requiring safety outcome studies for all new diabetes mellitus therapies remains justified. Given the burden of cardiovascular disease in patients with diabetes, the focus should shift towards cardiovascular outcome studies designed to evaluate efficacy (i.e. to determine the efficacy of a drug over placebo or standard care) rather than demonstrating that risk is not increased by a pre-specified safety margin. All stakeholders are responsible for ensuring that new drug approvals occur under conditions of appropriate safety and effectiveness. It is also a shared responsibility to avoid unnecessary hurdles that may compromise access to useful drugs and threaten the sustainability of health systems. It is critical to renew this debate so that stakeholders can collectively determine the optimal approach for developing new drugs to treat type 2 diabetes mellitus.

DPP-4 inhibitors and cardiovascular disease in type 2 diabetes mellitus. Expectations, observations and perspectives

AIMS

Cardiovascular disease (CVD) is the greatest burden of type 2 diabetes mellitus (T2DM) in terms of morbility, mortality and costs for individuals and societies. Therefore, its prevention is a major goal in diabetes care. Optimal treatment of hyperglycemia is certainly instrumental to CVD prevention. Optimal treatment means both establishing the most appropriate glycemic target for the given individual and selecting the medication(s) with the most favourable benefit/safety ratio. CVD safety, if not a clear CVD benefit, is certainly required for all antidiabetic agents. Dipeptidyl-peptidase-4 (DPP-4) inhibitors are among the classes of antidiabetic agents most recently made available for diabetes care. A major question to be addressed is the effect of these compounds on CVD. Expectations were high for their mechanism of action, which targets also post-prandial glucose and minimize hypoglycemia risk, thereby providing a sort of global glucose control, and for some potentially beneficial extra-glycemic effects. This article reviews the existing literature on this issue.

DATA SYNTHESIS

Data published so far document that DPP-4 inhibitors have a wide spectrum of glycemic and extra-glycemic effects potentially reducing the risk of CVD as well as favourable effects on intermediate or surrogate CVD endpoints. These data heralded a better CVD outcome. Accordingly, pooling CVD safety data from phase 3 and 4 studies conducted with DPP-4 inhibitors suggested that their use might translate into a better CVD outcome. Data from three CVD outcome RCTs with alogliptin, saxagliptin and sitagliptin documented no harm but did not show any benefit on major CVD events. A modest but significant increased risk of hospitalization for heart failure was observed with saxagliptin and with alogliptin (only in subjects with no history of heart failure before randomization) but not with sitagliptin. A study currently in progress with linagliptin will provide further insights in the issue of CVD safety and benefit.

CONCLUSIONS

It should be considered that most alternative oral antidiabetic agents generally do not possess a better CVD risk profile than DPP-4 inhibitors and that some of them, indeed, should be used with caution because of potentially adverse effects on heart and vasculature. Overall, the selection of antidiabetic agent(s) with the most favourable CVD profile is mandatory but still challenging in diabetes care.

Incretin therapies: highlighting common features and differences in the modes of action of glucagon-like peptide-1 receptor agonists and dipeptidyl peptidase-4 inhibitors

Over the last few years, incretin-based therapies have emerged as important agents in the treatment of type 2 diabetes (T2D). These agents exert their effect via the incretin system, specifically targeting the receptor for the incretin hormone glucagon-like peptide 1 (GLP-1), which is partly responsible for augmenting glucose-dependent insulin secretion in response to nutrient intake (the 'incretin effect'). In patients with T2D, pharmacological doses/concentrations of GLP-1 can compensate for the inability of diabetic β cells to respond to the main incretin hormone glucose-dependent insulinotropic polypeptide, and this is therefore a suitable parent compound for incretin-based glucose-lowering medications. Two classes of incretin-based therapies are available: GLP-1 receptor agonists (GLP-1RAs) and dipeptidyl peptidase-4 (DPP-4) inhibitors. GLP-1RAs promote GLP-1 receptor (GLP-1R) signalling by providing GLP-1R stimulation through 'incretin mimetics' circulating at pharmacological concentrations, whereas DPP-4 inhibitors prevent the degradation of endogenously released GLP-1. Both agents produce reductions in plasma glucose and, as a result of their glucose-dependent mode of action, this is associated with low rates of hypoglycaemia; however, there are distinct modes of action resulting in differing efficacy and tolerability profiles. Furthermore, as their actions are not restricted to stimulating insulin secretion, these agents have also been associated with additional non-glycaemic benefits such as weight loss, improvements in β-cell function and cardiovascular risk markers. These attributes have made incretin therapies attractive treatments for the management of T2D and have presented physicians with an opportunity to tailor treatment plans. This review endeavours to outline the commonalities and differences among incretin-based therapies and to provide guidance regarding agents most suitable for treating T2D in individual patients.

Very short-term effects of the dipeptidyl peptidase-4 inhibitor sitagliptin on the secretion of insulin, glucagon, and incretin hormones in Japanese patients with type 2 diabetes mellitus: analysis of meal tolerance test data

Background

Sitagliptin inhibits dipeptidyl peptidase-4, which inactivates the incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide. To assess its antidiabetic potency, we used meal tolerance tests (MTTs) to determine the very short-term effects of sitagliptin on plasma concentrations of insulin and glucagon.

Methods

On day 1, patients with newly diagnosed or uncontrolled type 2 diabetes mellitus started a calorie-restricted diet. On day 2, the first MTT was performed, before treatment with sitagliptin 50 mg/day started later the same day. On day 5, a second MTT was performed. Area under the concentration–time curves (AUCs) of relevant laboratory values were calculated [AUC from time zero to 2 h (AUC_0–2h) and from time zero to 4 h (AUC_0–4h)].

Results

Fifteen patients were enrolled. AUCs for postprandial plasma glucose were decreased after 3 days of sitagliptin treatment [AUC_0–2h 457 ± 115 mg/dL·h (25.4 ± 6.4 mmol/L·h) to 369 ± 108 mg/dL·h (20.5 ± 6.0 mmol/L·h); AUC_0–4h 896 ± 248 mg/dL·h (49.7 ± 13.8 mmol/L·h) to 701 ± 246 mg/dL·h (38.9 ± 13.7 mmol/L·h); both p < 0.001]. AUC_0–2h and AUC_0–4h for postprandial plasma glucagon also decreased: 195 ± 57 to 180 ± 57 pg/mL·h (p < 0.05) and 376 ± 105 to 349 ± 105 pg/mL·h (p < 0.01), respectively. The AUC_0–2h [median with quartile values (25 %, 75 %)] for active GLP-1 increased: 10.5 (8.5, 15.2) to 26.4 (16.7, 32.4) pmol/L·h (p = 0.03).

Conclusions

Very short-term (3-day) treatment with sitagliptin decreases postprandial plasma glucose significantly. This early reduction in glucose may result partly from suppression of excessive glucagon secretion, through a direct effect on active GLP-1. Improvement in postprandial plasma glucose, through suppression of glucagon secretion, is believed to be an advantage of sitagliptin for the treatment of patients with type 2 diabetes.

Sitagliptin for Type 2 diabetes: a 2015 update

Sitagliptin, a dipeptidyl peptidase 4 inhibitor, was the first in its class to receive approval from the US FDA in 2006 for the treatment of Type 2 diabetes mellitus. It has been evaluated in numerous clinical trials and has several attractive features as an antidiabetic agent, including a low risk for hypoglycemia, a neutral effect on weight, and an ability to be used in chronic kidney disease and more. This article provides an up-to-date discussion of the pharmacokinetics/pharmacodynamics, clinical efficacy, safety and tolerability of sitagliptin.

Dipeptidyl peptidase-4 inhibition and narrow-band ultraviolet-B light in psoriasis (DINUP): study protocol for a randomised controlled trial

BACKGROUND

Moderate to severe psoriasis is a systemic inflammatory disease associated with insulin resistance, obesity and type 2 diabetes (T2DM). Sitagliptin is a dipeptidyl peptidase-4 (DPP-4) inhibitor that improves glycaemia and has a marketing authorisation for the treatment of T2DM. Non-immunosuppressive therapies that are effective for psoriasis and its associated comorbidities would be a significant advance in the treatment of this chronic disease.

METHODS/DESIGN

This is a single centre, 39-week, prospective, randomised, open label, clinical trial of oral sitagliptin (Januvia(®)) in psoriasis patients who are due to undergo a course of narrow-band ultraviolet-B (NB-UVB) phototherapy. We plan to enrol 120 participants and allocate participants on a random and 1:1 basis to receive sitagliptin 100 mg daily for 24 weeks combined with NB-UVB or NB-UVB monotherapy. Participants will be followed up for 12 weeks after sitagliptin therapy is discontinued. The primary endpoint is the change in Psoriasis Area and Severity Index (PASI) 24 weeks after treatment initiation. Secondary endpoints include cumulative NB-UVB dose, number of NB-UVB treatments required to clear psoriasis, proportions of participants who achieve PASI-50 (50 % reduction in PASI from baseline), PASI-75, PASI-90 and the proportion of participants who relapse in each group. We will also analyse changes in cardiovascular disease risk factors, serum cytokine and hormone levels and peripheral blood mononuclear expression of immune proteins at 24 and 36 weeks. A subgroup of participants will have skin biopsies taken and analysed for skin levels and expression of immune cells, receptors, hormones and immune proteins. The genetic or epigenetic profile that predicts best response to DPP-4 inhibitor therapy will be analysed. The safety endpoints include the rate and severity of adverse events.

DISCUSSION

This is the first randomised clinical trial assessing dipeptidyl peptidase-4 inhibition therapy in psoriasis. We hypothesise that sitagliptin therapy in combination with NB-UVB improves psoriasis severity compared to NB-UVB monotherapy.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT02347501 (Date of registration: 27 January 2015).

Cardiovascular and heart failure safety profile of vildagliptin: a meta-analysis of 17 000 patients

AIMS

To report the cardiovascular (CV) safety profile and heart failure (HF) risk of vildagliptin from a large pool of studies, including trials in high-risk patients with type 2 diabetes mellitus (T2DM), such as those with congestive HF and/or moderate/severe renal impairment.

METHODS

We conducted a retrospective meta-analysis of prospectively adjudicated CV events. Patient-level data were pooled from 40 double-blind, randomized controlled phase III and IV vildagliptin studies. The primary endpoint was occurrence of major adverse CV events (MACEs; myocardial infarction, stroke and CV death). Assessments of the individual MACE components and HF events (requiring hospitalization or new onset) were secondary endpoints. The risk ratio (RR) of vildagliptin (50 mg once- and twice-daily combined) versus comparators (placebo and all non-vildagliptin treatments) was calculated using the Mantel-Haenszel (M-H) method.

RESULTS

Of the 17 446 patients, 9599 received vildagliptin (9251.4 subject-years of exposure) and 7847 received comparators (7317.0 subject-years of exposure). The mean age of the patients was 57 years, body mass index 30.5 kg/m(2) (nearly 50% obese), glycated haemoglobin concentration 8.1% and T2DM duration 5.5 years. A MACE occurred in 83 (0.86%) vildagliptin-treated patients and 85 (1.20%) comparator-treated patients, with an M-H RR of 0.82 [95% confidence interval (CI) 0.61-1.11]. Similar RRs were observed for the individual events. Confirmed HF events were reported in 41 (0.43%) vildagliptin-treated patients and 32 (0.45%) comparator-treated patients, with an M-H RR 1.08 (95% CI 0.68-1.70).

CONCLUSIONS

This large meta-analysis indicates that vildagliptin is not associated with an increased risk of adjudicated MACEs relative to comparators. Moreover, this analysis did not find a significant increased risk of HF in vildagliptin-treated patients.