Identification of levomenthol derivatives as potential dipeptidyl peptidase-4 inhibitors: a comparative study with gliptins

Dipeptidyl peptidase-4 (DPP4) inhibitors are a potent therapeutic treatment for type 2 diabetes mellitus (T2DM). There is a family of compounds used as DPP4 inhibitors (DPP4Is) called gliptins. They bind tightly to DPP4 to form an inactive protein-ligand complex. However, there remains a need to identify novel DPP4Is that are more efficacious and safer due to the increasing prevalence of T2DM and the undesirable side effects of gliptins. To identify potential DPP4Is, we screened over 1800 novel compounds in a comparative study with gliptins. We performed dual-factor molecular docking to assess the binding affinity of the compounds to DPP4 and found four compounds with a higher binding affinity to DPP4 than currently used gliptins. The newly identified compounds interacted with the dyad glutamate (GLU205 and GLU206) and tyrosine (TYR662 and TYR666) residues in DPP4's active site. We performed molecular dynamics simulations to determine the stability of the protein-ligand complexes formed by the compounds and DPP4. Furthermore, we examined the toxicity and pharmacological profile of the compounds. The compounds are drug-like, easy to synthesize, and relatively less toxic than gliptins. Collectively, our results suggest that the novel compounds are potential DPP4Is and should be considered for further studies to develop novel antidiabetics.Communicated by Ramaswamy H. Sarma.

Low dose sulphonylurea plus DPP4 inhibitor lower blood glucose and enhance beta cell function without hypoglycaemia

CONTEXT

Low dose sulphonylureas have been found to augment the classical incretin effect, increase glucose sensitivity and late phase incretin potentiation.

OBJECTIVE

To evaluate potential synergy between low dose sulphonylurea plus DPP4 inhibitor.

DESIGN

Unblinded randomised crossover study.

SETTING

Clinical Research Centre, University of Dundee.

PARTICIPANTS

30 participants with T2DM (HbA1c < 64 mmol/mol) treated with diet or metformin.

INTERVENTION

Participants completed four, 14-day blocks in a random order: control, gliclazide 20 mg (SU), sitagliptin 100 mg (DPP4i), or combination (SUDPP4i). A mixed meal test was conducted after each intervention.

MAIN OUTCOME MEASURE

The primary outcome was the effect of treatment on beta-cell glucose sensitivity. Secondary outcomes included frequency of glucose <3 mmol/l on continuous glucose monitoring, sub-analyses by genotype (KNCJ11 E23 K), gender and body mass index.

RESULTS

SU combination with DPP4i showed additive effect on glucose lowering: Mean glucose AUC (mean 95% CI) (mmol/l) was: Control 11.5 (10.7-12.3), DPP4i 10.2 (9.4-11.1), SU 9.7 (8.9-10.5), SUDPP4i 8.7 (7.9-9.5) (p < 0.001). Glucose sensitivity mirrored the additive effect (pmol min-1 m-2mM-1): Control 71.5 (51.1-91.9), DPP4i 75.9 (55.7-96.0), SU 86.3 (66.1-106.4), SUDPP4i 94.1 (73.9-114.3) (p = 0.04). The additive effect was seen in men but not women. Glucose time in range <3 mmol/l on CGM (%) was unaffected: Control 1 (2-4), DPP4i 2 (3-6), SU 1 (0-4), SUDPP4i 3 (2-7) (p = 0.65).

CONCLUSIONS

Low dose sulphonylurea plus DPP4i has potent glucose lowering effect through augmentation of beta cell function. A double-blind randomised controlled trial would formalise efficacy and safety of this combination, which may avoid negative aspects of SU.

Dominant PDX1 deficiency causes highly penetrant diabetes at different ages, associated with obesity and exocrine pancreatic deficiency: Lessons for precision medicine

OBJECTIVE

Heterozygous pathogenic or likely pathogenic (P/LP) PDX1 variants cause monogenic diabetes. We comprehensively examined the phenotypes of carriers of P/LP PDX1 variants, and delineated potential treatments that could be efficient in an objective of precision medicine.

METHODS

The study primarily involved a family harboring a novel P/LP PDX1 variant. We then conducted an analysis of documented carriers of P/LP PDX1 variants, from the Human Gene Mutation Database (HGMD), RaDiO study, and Type 2 Diabetes Knowledge Portal (T2DKP) including 87 K participants.

RESULTS

Within the family, we identified a P/LP PDX1 variant encoding p.G232S in four relatives. All of them exhibited diabetes, albeit with very different ages of onset (10-40 years), along with caudal pancreatic agenesis and childhood-onset obesity. In the HGMD, 79 % of carriers of a P/LP PDX1 variant displayed diabetes (with differing ages of onset from eight days of life to 67 years), 63 % exhibited pancreatic insufficiency and surprisingly 40 % had obesity. The impact of P/LP PDX1 variants on increased risk of type 2 diabetes mellitus was confirmed in the T2DKP. Dipeptidyl peptidase 4 inhibitor (DPP4i) and glucagon-like peptide-1 receptor agonist (GLP1-RA), enabled good glucose control without hypoglycemia and weight management.

CONCLUSIONS

This study reveals diverse clinical presentations among the carriers of a P/LP PDX1 variant, highlighting strong variations in diabetes onset, and unexpectedly high prevalence of obesity and pancreatic development abnormalities. Clinical data suggest that DPP4i and GLP1-RA may be the best effective treatments to manage both glucose and weight controls, opening new avenue in precision diabetic medicine.

Sodium-glucose cotransporter-2 (SGLT2) inhibitors and the reporting of falls and fractures: an european pharmacovigilance analysis

Background: The risk of falls and bone fractures with sodium-glucose co-transporter-2 (SGLT2) inhibitors has been characterized by conflicting evidence. Therefore, we decided to investigate the reporting probability of falls and fractures by comparing SGLT2 inhibitors with DPP4 inhibitors. Methods A retrospective, pharmacovigilance study of the European database of Individual Case Safety Reports (ICSRs) was conducted. Disproportionality analyses (Reporting Odds Ratio, ROR) were conducted to compare the reporting probability of falls or fracture between treatments. Results A total of 507 ICSRs reporting at least one fall or fracture with SGLT2 inhibitors were identified. The most reported SGLT2 inhibitor was canagliflozin (N = 188; 36.9%), followed by empagliflozin (N = 176; 34.5%), and dapagliflozin (N = 143; 28.0%). A total of 653 events related to fall or bone fracture were reported. Fall was the most reported event (N = 333; 51.0%). Among fractures (N = 320; 49.0%), the most reported were foot fractures (N = 40; 6.1%) and hip fractures (N = 32; 4.9%). SGLT2 inhibitors were associated with a lower reporting probability of fall than DPP4 inhibitors (ROR, 0.66; 95%CI, 0.57-0.78). The lower reporting probability of fall was also observed when the single SGLT2 inhibitor was compared to DPP4 inhibitors: dapagliflozin (ROR, 0.67; 95%CI, 0.53-0.83), canagliflozin (ROR, 0.56; 95%CI, 0.45-0.70), and empagliflozin (ROR, 0.77; 95%CI, 0.63-0.94). For fractures, canagliflozin showed a slightly significant increased reporting when compared with DPP4 inhibitors (not confirmed in the sensitivity analysis), whereas all other comparison showed no statistically significant difference. Conclusion SGLT2 inhibitors were associated with a lower reporting probability of fall than DPP4 inhibitors, in accordance with the reassuring evidence about the safety profile of these drugs. Future researches will help to confirm their long-term safety profile.

Dipeptidylpeptidase 4 promotes survival and stemness of acute myeloid leukemia stem cells

Leukemic-stem-cell-specific targeting may improve the survival of patients with acute myeloid leukemia (AML) by avoiding the ablative effects of standard regimens on normal hematopoiesis. Herein, we perform an unbiased screening of compounds targeting cell surface proteins and identify clinically used DPP4 inhibitors as strong suppressors of AML development in both murine AML models and primary human AML cells xenograft model. We find in retrovirus-induced AML mouse models that DPP4-deficient AML cell-transplanted mice exhibit delay and reversal of AML development, whereas deletion of DPP4 has no significant effect on normal hematopoiesis. DPP4 activates and sustains survival of AML stem cells that are critical for AML development in both human and animal models via binding with Src kinase and activation of nuclear factor κB (NF-κB) signaling. Thus, inhibition of DPP4 is a potential therapeutic strategy against AML development through suppression of survival and stemness of AML cells.

Dipeptidyl peptidase 4(DPP4) inhibitors stride up the management of Parkinson's disease

Parkinson's disease (PD) is the 2^nd most common age-related hypokinetic disorder, characterized by dopaminergic degeneration and movement abnormalities. Dopaminergic degeneration in the basal ganglia is primarily seen in PD patients. The therapeutic strategies currently under investigation are to rescue dopaminergic degeneration and promote neuronal regeneration, which could halt disease progression. On the other hand, the therapeutic efficacy of existing drugs used in other disorders has been repurposed in neurodegenerative pathologies. DPP4 inhibitors widely used in treating diabetes have been considered viable target sites and are being tested for efficacy in neurodegenerative pathologies. DPP4 inhibitors have been reported to rescue neuronal degeneration and improve motor functions in various preclinical and clinical PD studies. The current review is focused on the neuroprotective potential, molecular mechanisms and therapeutic potential of DPP4 inhibitors in PD pathology.

DPP4 Inhibitor-Induced Bullous Pemphigoid in Patients with Diabetes and Chronic Kidney Disease: Clinical Case Series

INTRODUCTION

Dipeptidyl peptidase-4 (DPP4) inhibitors (gliptins) are commonly prescribed for glucose control in patients with advanced chronic kidney disease (CKD) in whom other oral glucose-lowering agents are contraindicated. In the past few years, new reports of drug-induced bullous pemphigoid associated with DPP4 inhibitors have emerged. However, there is not enough information about the renal function of the patients with DPP4 inhibitor-induced bullous pemphigoid, and it remains unknown whether the risk of this complication is increased among patients with CKD.

CASE REPORTS

Five patients with stage 3b-5 CKD received a diagnosis of DPP4 inhibitor-associated bullous pemphigoid in our institution within a period of 17 months (between December 2018 and May 2020). All patients in the current series were male. Skin biopsies were performed in all patients. Three cases were secondary to vildagliptin, and 2 cases were attributed to linagliptin. In each of these patients, treatment consisted of permanent discontinuation of the DPP4 inhibitor and administration of corticosteroids.

CONCLUSION

We report here the first single-center experience of DPP4 inhibitor-induced bullous pemphigoid in patients with CKD. Our case series highlights the importance of considering bullous pemphigoid in patients with CKD taking DPP4 inhibitors presenting with bullous or pruritic cutaneous lesions. By calling attention to this important complication, we hope to minimize the delay in diagnosing DPP4 inhibitor-induced bullous pemphigoid among patients with CKD.

DPP4 Inhibitors: Could they be One of the Solutions for COVID-19 Patients with Prediabetes?

Recent reports suggest that prediabetes is a risk factor for developing severe COVID-19 complications through underlying mechanisms involving undiagnosed sub-clinical inflammation. However, we remain without a clinical approach for managing COVID-19 in prediabetic cases. The subclinical inflammation in prediabetes is associated with elevated DPP4 levels and activity. DPP4 has pleiotropic actions, including glycaemia regulation and immuno-modulation. Recently, DPP4 has been recognised as a co-receptor for COVID-19 for entering host cells. In addition to improving glycaemia, DPP4 inhibition is associated with reduced inflammation. In this submission, we explore the potential use of DPP4 inhibitors as therapeutic agents for prediabetic patients in managing the deleterious effects of COVID-19. DPP4 inhibitors (gliptins), such as linagliptin and sitagliptin, have therapeutic effects, which have been shown to extend beyond glycaemic control with no risk of hypoglycaemia. By the nature of their mechanism of action, gliptins are not associated with hypoglycaemia, unlike their anti-glycaemic counterparts, as they mainly target postprandial glycaemia. Moreover, DPP4 inhibitors may represent a safer option for prediabetic individuals in managing prediabetes either as a prophylactic or curative treatment for COVID-19. We envisage that beyond improved glycaemic control, the use of DPP4 inhibitors would also alleviate the cytokine storm, resulting in a reduction in the severity of COVID-19 symptoms and consequently reducing the morbidity and mortality in prediabetic COVID- 19 patients.

The Anti-Inflammatory Effect of Novel Antidiabetic Agents

The incidence of type 2 diabetes (T2DM) has been increasing worldwide and remains one of the leading causes of atherosclerotic disease. Several antidiabetic agents have been introduced in trying to regulate glucose control levels with different mechanisms of action. These agents, and sodium-glucose cotransporter-2 inhibitors in particular, have been endorsed by contemporary guidelines in patients with or without T2DM. Their widespread usage during the last three decades has raised awareness in the scientific community concerning their pleiotropic mechanisms of action, including their putative anti-inflammatory effect. In this review, we delve into the anti-inflammatory role and mechanism of the existing antidiabetic agents in the cardiovascular system and their potential use in other chronic sterile inflammatory conditions.

Effectiveness and safety of new oral and injectable agents for in-hospital management of type 2 diabetes in general wards: Systematic review and meta-analysis

BACKGROUND

Current guidelines recommend insulin alone for in-hospital management of diabetes, but growing information suggests that new oral or injectable agents may be as effective and safe.

METHODS

Systematic review and meta-analysis with evidence from randomized (RCT) and non-randomized (NRS) studies in PubMed, EMBASE and LILACS databases up to February 10, 2022, for studies including hospitalized type 2 diabetes patients, comparing dipeptidyl peptidase 4 inhibitors (DPP4i), sodium glucose co-transporter 2 inhibitors (SGLT2i) and glucagon-like peptide-1 receptor agonist (GLP1Ra) with insulin alone for glycemic control and safety outcomes.

FINDINGS

7 RCT and 3 NRTs were included. There were no differences in mean blood glucose, measurements within range or rate of hypoglycemia between DPP4i and insulin. We found a lower mean glucose for GLP1Ra plus insulin subgroup (-16.36 mg/dL, 95 % CI -27.31, -5.41; I² = 0 %) with lower incidence of hypoglycemia < 70 mg/dL with GLP1Ra (RR 0.31, CI 95 % 0.14-0.70, I² = 0 %). SGLT2i data was limited. Adverse events rates were similar between treatments.

CONCLUSION

Our review suggests that inpatient management in the general ward with DPP4i and GLP1Ra is as effective and safe as management with insulin. More randomized studies are required to support these findings before they could be recommended as usual practice.

Cardiovascular protection by DPP-4 inhibitors in preclinical studies: an updated review of molecular mechanisms

Dipeptidyl peptidase 4 (DPP4) inhibitors are a class of antidiabetic medications that cause glucose-dependent increase in incretins in diabetic patients. One of the two incretins, glucagon-like peptide-1 (GLP-1), beside its insulinotropic activity, has been studied for extra pancreatic effects. Most of DPP4 inhibitors (DPP4i) have been investigated in in vivo and in vitro models of diabetic and nondiabetic cardiovascular diseases including heart failure, hypertension, myocardial ischemia or infarction, atherosclerosis, and stroke. Results of preclinical studies proved prominent therapeutic potential of DPP4i in cardiovascular diseases, regardless the presence of diabetes. This review aims to present an updated summary of the cardiovascular protective and therapeutic effects of DPP4 inhibitors through the past 5 years focusing on the molecular mechanisms beneath these effects. Additionally, based on the results summary presented here, future studies may be conducted to elucidate or illustrate some of these findings which can add clinical benefits towards management of diabetic cardiovascular complications.

Real-world evaluation of sodium-glucose co-transporter-2 inhibitors and dipeptidyl peptidase-4 inhibitors for managing type 2 diabetes mellitus: a retrospective multi-ethnic cohort study

Abstract

Purpose

Sodium-glucose co-transporter-2 (SGLT2) inhibitors and dipeptidyl peptidase-4 (DPP4) inhibitors are increasingly used as second-line therapies in patients with type 2 diabetes. The aim of this study was to assess the real-world effects of SGLT2 inhibitors in a multi-ethnic population in Singapore.

Methods

This retrospective cohort study examined patients diagnosed with and treated for diabetes from the Ministry of Health’s administrative database. Differences in outcomes between treatment groups were assessed using Poisson regression. Demographics, clinical characteristics, previous diagnoses and hospitalisations, and diabetes medication history were used for propensity score matching. Subgroup analyses by ethnicity were performed. Effect size was estimated using risk ratios (RRs) with 95% confidence intervals (CIs).

Results

Patients initiating SGLT2 inhibitors were more likely to achieve glycaemic control target than DPP4 inhibitor-treated patients (RR 1.09; 95% CI 1.04, 1.14). This was observed only in patients of Chinese ethnicity. A higher risk of diabetic ketoacidosis in SGLT2 inhibitor initiators was not observed. SGLT2 inhibitors were associated with reduced risk of hypoglycaemia (RR 0.69; 95% CI 0.59, 0.82) and urinary tract infection (RR 0.52; 95% CI 0.43, 0.63) but was not statistically significant for hypoglycaemia in Malay patients. Compared to DPP4 inhibitors, SGLT2 inhibitors were associated with 12% and 34% reduction in any-cause hospitalisation and all-cause mortality, respectively, potentially resulting in more than $50 million savings over 10 years.

Conclusion

SGLT2 inhibitors were associated with improvements in glycaemic control, reduced risk of complications, and was well tolerated. Ethnicity also plays a role and should be considered in future studies.

The Effects of the New Therapeutic Treatments for Diabetes Mellitus on the Male Reproductive Axis

One of the complications of chronic hyperglycemia and insulin resistance due to type 2 diabetes mellitus (T2DM) on the hypothalamic-pituitary-gonadal axis in men, is the high prevalence of hypogonadotropic hypogonadism, which has been recently defined as functional hypogonadism, characterized by low testosterone associated with inappropriately normal gonadotropin levels. Although the pathophysiology of this hormonal imbalance may be related to several factors, including glycemic control, concomitant sleep apnea, insulin resistance, the main role is determined by the degree of central or visceral obesity and the consequent inflammatory state. Several drugs have been developed to treat T2DM such as glucagon-like peptide-1 receptor agonists, dipeptidyl peptidase 4 inhibitors, and sodium-glucose co-transporter 2 inhibitors. All appear to be effective in ameliorating blood glucose control, by lowering inflammation and body weight, and most seem to reduce the risk of micro- and macrovascular damage as a consequence of uncontrolled diabetes. A few studies have evaluated the impact of these drugs on gonadal function in T2DM patients with hypogonadism, with promising results. This review summarizes the main current knowledge of the effects of these new antidiabetic drugs on the hypothalamus-pituitary-gonadal axis, showing their potential future application in addition to glucose control in dysmetabolic male patients.

The Roles of Dipeptidyl Peptidase 4 (DPP4) and DPP4 Inhibitors in Different Lung Diseases: New Evidence

CD26/Dipeptidyl peptidase 4 (DPP4) is a type II transmembrane glycoprotein that is widely expressed in various organs and cells. It can also exist in body fluids in a soluble form. DPP4 participates in various physiological and pathological processes by regulating energy metabolism, inflammation, and immune function. DPP4 inhibitors have been approved by the Food and Drug Administration (FDA) for the treatment of type 2 diabetes mellitus. More evidence has shown the role of DPP4 in the pathogenesis of lung diseases, since it is highly expressed in the lung parenchyma and the surface of the epithelium, vascular endothelium, and fibroblasts of human bronchi. It is a potential biomarker and therapeutic target for various lung diseases. During the coronavirus disease-19 (COVID-19) global pandemic, DPP4 was found to be an important marker that may play a significant role in disease progression. Some clinical trials on DPP4 inhibitors in COVID-19 are ongoing. DPP4 also affects other infectious respiratory diseases such as Middle East respiratory syndrome and non-infectious lung diseases such as pulmonary fibrosis, lung cancer, chronic obstructive pulmonary disease (COPD), and asthma. This review aims to summarize the roles of DPP4 and its inhibitors in infectious lung diseases and non-infectious diseases to provide new insights for clinical physicians.

Use of incretin-based drugs and risk of cholangiocarcinoma: Scandinavian cohort study

AIMS/HYPOTHESIS

Concerns have been raised regarding a potential association of use of the incretin-based drugs dipeptidyl peptidase 4 (DPP4) inhibitors and glucagon-like peptide-1 (GLP-1)-receptor agonists with risk of cholangiocarcinoma. We examined this association in nationwide data from three countries.

METHODS

We used data from nationwide registers in Sweden, Denmark and Norway, 2007-2018, to conduct two cohort studies, one for DPP4 inhibitors and one for GLP-1-receptor agonists, to investigate the risk of incident cholangiocarcinoma compared with an active-comparator drug class (sulfonylureas). The cohorts included patients initiating treatment episodes with DPP4 inhibitors vs sulfonylureas, and GLP-1-receptor agonists vs sulfonylureas. We used Cox regression models, adjusted for potential confounders, to estimate hazard ratios from day 366 after treatment initiation to account for cancer latency.

RESULTS

The main analyses of DPP4 inhibitors included 1,414,144 person-years of follow-up from 222,577 patients receiving DPP4 inhibitors (median [IQR] follow-up time, 4.5 [2.6-7.0] years) and 123,908 patients receiving sulfonylureas (median [IQR] follow-up time, 5.1 [2.9-7.8] years) during which 350 cholangiocarcinoma events occurred. Use of DPP4 inhibitors, compared with sulfonylureas, was not associated with a statistically significant increase in risk of cholangiocarcinoma (incidence rate 26 vs 23 per 100,000 person-years; adjusted HR, 1.15 [95% CI 0.90, 1.46]; absolute rate difference 3 [95% CI -3, 10] events per 100,000 person-years). The main analyses of GLP-1-receptor agonists included 1,036,587 person-years of follow-up from 96,813 patients receiving GLP-1-receptor agonists (median [IQR] follow-up time, 4.4 [2.4-6.9] years) and 142,578 patients receiving sulfonylureas (median [IQR] follow-up time, 5.5 [3.2-8.1] years) during which 249 cholangiocarcinoma events occurred. Use of GLP-1-receptor agonists was not associated with a statistically significant increase in risk of cholangiocarcinoma (incidence rate 26 vs 23 per 100,000 person-years; adjusted HR, 1.25 [95% CI 0.89, 1.76]; absolute rate difference 3 [95% CI -5, 13] events per 100,000 patient-years).

CONCLUSIONS/INTERPRETATION

In this analysis using nationwide data from three countries, use of DPP4 inhibitors and GLP-1-receptor agonists, compared with sulfonylureas, was not associated with a significantly increased risk of cholangiocarcinoma.

Effect of Add-On Therapy of Sodium-Glucose Cotransporter 2 Inhibitors and Dipeptidyl Peptidase 4 Inhibitors on Adipokines in Type 2 Diabetes Mellitus

Background

Excess adiposity is associated with an increased risk of cardiovascular disease due to metabolic changes in the body. Visceral obesity increases the risk of diabetes mellitus through adipocytokines and hence the effective targeting therapies are essential to control obesity in high-risk individuals. The study's main objective was to evaluate the effect of add-on therapy of sodium-glucose cotransporter 2 (SGLT2) inhibitors and dipeptidyl peptidase 4 (DPP4) inhibitors on visceral fat-associated serum adipokines.

Methods

The study included 90 subjects diagnosed with type 2 diabetes mellitus. The blood samples were taken before starting first-line therapy with metformin, 12 weeks after starting metformin therapy and 12 weeks after starting add-on therapy. Serum adipokines were analyzed with enzyme-linked immunosorbent assay (ELISA). Hemoglobin A1c (HbA1c) level was estimated with high-performance liquid chromatography (HPLC). The biochemical variables were measured using Cobas^® 6000 analyzer.

Results

The mean adiponectin level was significantly elevated with add-on therapy using SGLT2 inhibitors and DPP4 inhibitors (P < 0.001). The mean retinol binding protein 4 (RBP4), fatty acid binding protein 4 (FABP4) and visfatin levels were reduced considerably (P < 0.001). The SGLT2 inhibitors are more effective on serum FABP4 in patients with type 2 diabetes (P = 0.038). The mean fasting plasma glucose (FPG), postprandial blood glucose (PPBG) and HbA1c levels were reduced significantly with add-on therapy (P < 0.001). Lipid profile was also altered significantly with this add-on therapy (P < 0.001).

Conclusions

The results indicate that add-on therapy exerts a beneficial effect in type 2 diabetic patients insufficiently controlled with metformin only by altering the visceral fat-associated adipokine levels and controlling the metabolic activities.

Beneficial effects of dipeptidyl peptidase-4 inhibitors in diabetic Parkinson's disease

Dipeptidyl peptidase 4 (DPP4) inhibitors are widely used hypoglycaemic agents and improve glucose metabolism by enhancing the bioavailability of active glucagon-like peptide-1. In this study, we hypothesized that treatment with DPP4 inhibitors may have beneficial effects on nigrostriatal dopamine and longitudinal motor performance in diabetic patients with Parkinson's disease. We classified 697 drug naive patients with de novo Parkinson's disease who had undergone dopamine transporter imaging into three groups according to a prior diagnosis of diabetes and use of DPP4 inhibitors: diabetic patients with Parkinson's disease being treated with (n = 54) or without DPP4 inhibitors (n = 85), and non-diabetic patients with Parkinson's disease (n = 558). Diabetic patients with Parkinson's disease being treated with DPP4 inhibitors had a higher baseline dopamine transporter availability in the anterior (2.56 ± 0.74 versus 2.10 ± 0.50; P = 0.016), posterior (1.83 ± 0.69 versus 1.40 ± 0.50; P < 0.001), and ventral putamina (1.72 ± 0.58 versus 1.35 ± 0.37; P = 0.001) than that in diabetic patients with Parkinson's disease without DPP4 inhibitors. Additionally, diabetic patients with Parkinson's disease being treated with DPP4 inhibitors had higher dopamine transporter availability in the posterior putamen than that in non-diabetic patients with Parkinson's disease (1.83 ± 0.69 versus 1.43 ± 0.59; P < 0.001). After adjusting for age, sex, disease duration, and vascular risk factors, linear regression models showed that a prior treatment of DPP4 inhibitors remained independently and significantly associated with dopamine transporter availability in the anterior (β = -0.186, P = 0.012; β = -0.207, P = 0.003), posterior (β = -0.336, P < 0.001; β = -0.286, P < 0.001), and ventral putamina (β = -0.204, P = 0.005; β = -0.250, P < 0.001). A linear mixed model revealed that the diabetic group with Parkinson's disease being treated with DPP4 inhibitors had a slower longitudinal increase in levodopa-equivalent dose than the other groups (P = 0.003). Survival analyses showed that the rate of levodopa-induced dyskinesia was significantly lower in the diabetic group with a prior treatment with DPP4 inhibitors than the diabetic group without DPP4 inhibitors (hazard ratio = 0.194, P = 0.037). These findings suggest that DPP4 inhibitors may confer beneficial effects on the baseline nigrostriatal dopamine degeneration and long-term motor outcomes in diabetic patients with Parkinson's disease and may extend its role into non-diabetic patients with Parkinson's disease.

Investigation into the role of anti-diabetic agents in cachexia associated with metastatic cancer

Cancer cachexia (CC) is a syndrome associated with cancer, and the global burden is increasing rapidly. Alteration in carbohydrate, lipid and protein metabolism along with systemic inflammation are characteristics of CC. Until now the available treatment for CC is limited to controlling inflammation and nutrition. Anti-diabetics are widely used agents to treat diabetics, this agent's act by regulating the carbohydrate metabolism, also they are known to have beneficial effects in maintaining protein and lipid balance. Role of anti-diabetics in cancer is being evaluated continuously and biguanides, dipeptidyl peptidase 4 (DPP4) inhibitors and Sodium glucose co-transporter 2 (SGLT2) inhibitors have proven anti-cancer potential. In this study, metastatic B16-F1 cell line induced cancer cachexia model used to evaluate potential of biguanides (metformin), DPP-4 inhibitors (teneligliptin and vildagliptin) and SGLT2 inhibitors (empagliflozin and dapagliflozin) in cancer cachexia. Our results suggest that anti-diabetic agents have potential to decrease rate of proliferation of tumor, restrict body mass markers, decrease inflammation, regulate carbohydrate mechanism and induce skeletal muscle hypertrophy. These findings may be helpful in management of cancer cachexia and increase the quality of life and survival chances of cancer cachexia patient.

Glucose-Lowering Medications and Cardiovascular Outcomes

PURPOSE OF THE REVIEW

The purpose of this review is to examine recent evidence supporting CV safety profile and improvement of CV outcomes of some of the newer classes of diabetic medications.

RECENT FINDINGS

Diabetes mellitus (DM) is associated with increased risk of cardiovascular disease (CVD). Thus, CVD management is critical in diabetic patients. Since 2008, the US Food and Drug Administration (FDA) has mandated that all newer diabetic medications should establish cardiovascular safety before it is approved for use. Diabetic medications that also lower CV risk would be a significant advancement as shown in recent studies. There are 3 new class of diabetic medications: Dipeptidyl peptidase-4 inhibitors (DPP-4), glucagon-like peptide receptor agonists (GLP-1 RA), and sodium-glucose cotransporter type 2 (SGLT 2) inhibitors which have established both CV safety and improvement in CV outcomes with some drugs. In patients with type 2 diabetes and established atherosclerotic cardiovascular disease, multiple atherosclerotic cardiovascular disease risk factors, or diabetic kidney disease, a sodium-glucose cotransporter 2 inhibitor, or a glucagon-like peptide 1 receptor agonist with demonstrated cardiovascular benefit is recommended to reduce the risk of major adverse cardiovascular events.

The association of socioeconomic disadvantage and remoteness with receipt of type 2 diabetes medications in Australia: a nationwide registry study

AIMS/HYPOTHESIS

In recent years, several new medications for the treatment of type 2 diabetes have been released and some evidence indicates sociodemographic disparity in their utilisation. We sought to investigate sociodemographic disparities in receipt of diabetes medications across Australia.

METHODS

This study included 1,203,317 people with type 2 diabetes registered on the Australian National Diabetes Services Scheme (NDSS) followed from 2007 to 2015. The NDSS was linked to the Australian pharmaceutical claims database. We investigated trends in diabetes medication dispensing and variation in dispensing by sociodemographic strata.

RESULTS

Compared with individuals in the least disadvantaged areas, those in the most disadvantaged quintile were less likely to receive dipeptidyl peptidase-4 inhibitors (DPP4is), glucagon-like peptide-1 receptor agonists (GLP-1RAs) and sodium-glucose cotransporter 2 inhibitors (SGLT2is) in the first year of availability (OR [95% CI] for most vs least disadvantaged: 0.78 [0.75, 0.82], 0.65 [0.60, 0.71] and 0.89 [0.84, 0.95], respectively). These disparities dissipated over time for DPP4is and SGLT2is but remained significant for GLP-1RAs. The OR (95% CI) of receiving DPP4is, GLP-1RAs and SGLT2is in the first year of availability for people in remote areas vs major cities was 0.46 (0.39, 0.54), 0.46 (0.35, 0.61) and 0.71 (0.59, 0.84), respectively. These disparities remained significant through to 2015.

CONCLUSIONS/INTERPRETATION

People with diabetes in more disadvantaged areas are less likely to receive newer diabetes medications, although this effect decreased over time. However, there are considerable and persistent differences in receipt of newer diabetes medications between major cities and remote areas of Australia. Graphical abstract.

Use of DPP4 inhibitors in Italy does not correlate with diabetes prevalence among COVID-19 deaths

In a nationwide study of 3818 charts from patients with fatal COVID-19, we found that geographical differences in Dipeptidyl peptidase 4 (DPP4) inhibitors use did not correlate with diabetes prevalence among COVID-19 deaths, thus not supporting the hypothesis of a clinically relevant involvement of DPP4 inhibition in COVID-19 development and progression.

Real-world adherence, persistence, and in-class switching during use of dipeptidyl peptidase-4 inhibitors: a systematic review and meta-analysis involving 594,138 patients with type 2 diabetes

AIMS

Medication adherence and persistence are important determinants of treatment success in type 2 diabetes mellitus (T2DM). This systematic review and meta-analysis evaluated the real-world adherence, persistence, and in-class switching among patients with T2DM prescribed dipeptidyl peptidase-4 (DPP4) inhibitors.

METHODS

MEDLINE, EMBASE, Cochrane Library, PsychINFO, and CINAHL were searched for relevant observational studies published in the English language up to 20 December 2019. This was supplemented by manual screening of the references of included papers. Random-effects meta-analysis was performed.

RESULTS

Thirty-four cohort studies involving 594,138 patients with T2DM prescribed DPP4 inhibitors from ten countries were included. The pooled proportion adherent (proportion of days covered (PDC) or medication possession ratio (MPR) ≥ 0.80) was 56.9% (95% confidence interval [CI] 49.3-64.4) at one year and 44.2% (95% CI 36.4-52.1) at two years. The proportion persistent with treatment decreased from 75.6% (95% CI 71.5-79.5) at six months to 52.8% (95% CI 51.6-59.8) at two years. No significant differences in adherence and persistence were observed between individual DPP4 inhibitors. At one year, just 3.2% (95% CI 3.1-3.3) of patients switched from one DPP4 inhibitor to another. Switching from saxagliptin and alogliptin to others was commonest.

CONCLUSIONS

Adherence to and persistence with DPP4 inhibitors is suboptimal but similar across all medications within the class. While in-class switching is uncommon, saxagliptin and alogliptin are the DPP4 inhibitors most commonly switched. Interventions to improve treatment adherence and persistence among patients with T2DM prescribed DPP4 inhibitors may be warranted.

Roles and Mechanisms of Dipeptidyl Peptidase 4 Inhibitors in Vascular Aging

Vascular aging is characterized by alterations in the constitutive properties and biological functions of the blood vessel wall. Endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) are indispensability elements in the inner layer and the medial layer of the blood vessel wall, respectively. Dipeptidyl peptidase-4 (DPP4) inhibitors, as a hypoglycemic agent, play a protective role in reversing vascular aging regardless of their effects in meliorating glycemic control in humans and animal models of type 2 diabetes mellitus (T2DM) through complex cellular mechanisms, including improving EC dysfunction, promoting EC proliferation and migration, alleviating EC senescence, obstructing EC apoptosis, suppressing the proliferation and migration of VSMCs, increasing circulating endothelial progenitor cell (EPC) levels, and preventing the infiltration of mononuclear macrophages. All of these showed that DPP4 inhibitors may exert a positive effect against vascular aging, thereby preventing vascular aging-related diseases. In the current review, we will summarize the cellular mechanism of DPP4 inhibitors regulating vascular aging; moreover, we also intend to compile the roles and the promising therapeutic application of DPP4 inhibitors in vascular aging-related diseases.

Dipeptidyl peptidase 4 inhibitors attenuate cardiac ischaemia-reperfusion injury in rats with diabetes mellitus type 2

The aim of our study was to assess and compare the effects of dipeptidyl peptidase 4 (DPP4) inhibitors, saxagliptin and sitagliptin, on metabolic control of disease and cardiac function in rats with diabetes mellitus type 2 (T2DM). This research would provide novel understanding into the potentially protective effects of DPP4 inhibitors in helping salvage of the heart exposed to ischaemia-reperfusion (I-R) injury. Forty-eight Wistar albino rats were randomly divided into four groups: CTRL, Control healthy group; T2DM, rats with T2DM; T2DM + Sit, rats with T2DM treated with 0.6 mg/kg of sitagliptin; T2DM + Sax, rats with T2DM treated with 0.45 mg/kg of saxagliptin for 3 weeks. At the end of the protocol, in vivo cardiac function was assessed by echocardiography, while in the blood samples glucose and insulin were determined. Additionally, ex vivo heart function was estimated on a model of I-R injury using Langendorff apparatus. Immunohistochemical analysis was used to determine the degree of myocardial apoptosis and necrosis, while DPP4 staining was performed to assess the cardiac DPP4 expression. Data were analyzed using a one-way analysis of variance (ANOVA) and the post hoc Bonferroni test for multiple comparisons. Improved glycoregulation was noticed in rats that received DPP4 inhibitors compared to untreated diabetic rats (P < .05). Moreover, better in vivo systolic function was observed in rats treated with both DPP4 inhibitors as evidenced by an increase in fractional shortening when compared to T2DM (P < .05). Most parameters of cardiac function in treated rats remained unaltered during reperfusion, thus suggesting that both drugs protected myocardium during flow restoration. Better effects on coronary circulation were achieved after sitagliptin application. Additionally, both DPP4 inhibitors showed similar potential to attenuate cardiac necrosis and apoptosis. Saxagliptin and sitagliptin might be efficient in preserving myocardial function and morphology in ex vivo induced I-R cardiac injury in rats with T2DM.

No significant association between dipeptidyl peptidase-4 inhibitors and adverse outcomes of COVID-19

BACKGROUND

Dipeptidyl peptidase-4 (DPP4) is commonly targeted to achieve glycemic control and has potent anti-inflammatory and immunoregulatory effects. Recent structural analyses indicated a potential tight interaction between DPP4 and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), raising a promising hypothesis that DPP4 inhibitor (DPP4i) drugs might be an optimal strategy for treating coronavirus disease 2019 (COVID-19) among patients with diabetes. However, there has been no direct clinical evidence illuminating the associations between DPP4i use and COVID-19 outcomes.

AIM

To illuminate the associations between DPP4i usage and the adverse outcomes of COVID-19.

METHODS

We conducted a multicenter, retrospective analysis including 2563 patients with type 2 diabetes who were hospitalized due to COVID-19 at 16 hospitals in Hubei Province, China. After excluding ineligible individuals, 142 patients who received DPP4i drugs and 1115 patients who received non-DPP4i oral anti-diabetic drugs were included in the subsequent analysis. We performed a strict propensity score matching (PSM) analysis where age, sex, comorbidities, number of oral hypoglycemic agents, heart rate, blood pressure, pulse oxygen saturation (SpO₂) < 95%, CT diagnosed bilateral lung lesions, laboratory indicators, and proportion of insulin usage were matched. Finally, 111 participants treated with DPP4i drugs were successfully matched to 333 non-DPP4i users. Then, a linear logistic model and mixed-effect Cox model were applied to analyze the associations between in-hospital DPP4i use and adverse outcomes of COVID-19.

RESULTS

After rigorous matching and further adjustments for imbalanced variables in the linear logistic model and Cox adjusted model, we found that there was no significant association between in-hospital DPP4i use (DPP4i group) and 28-d all-cause mortality (adjusted hazard ratio = 0.44, 95%CI: 0.09-2.11, P = 0.31). Likewise, the incidences and risks of secondary outcomes, including septic shock, acute respiratory distress syndrome, or acute organ (kidney, liver, and cardiac) injuries, were also comparable between the DPP4i and non-DPP4i groups. The performance of DPP4i agents in achieving glucose control (e.g., the median level of fasting blood glucose and random blood glucose) and inflammatory regulation was approximately equivalent in the DPP4i and non-DPP4i groups. Furthermore, we did not observe substantial side effects such as uncontrolled glycemia or acidosis due to DPP4i application relative to the use of non-DPP4i agents in the study cohort.

CONCLUSION

Our findings demonstrated that DPP4i use is not significantly associated with poor outcomes of COVID-19 or other adverse effects of anti-diabetic treatment. The data support the continuation of DPP4i agents for diabetes management in the setting of COVID-19.

DPP4 inhibition: Preventing SARS-CoV-2 infection and/or progression of COVID-19?

Dipeptidyl peptidase 4 (DPP4), also known as cluster of differentiation 26 (CD26), is a serine exopeptidase expressed ubiquitously in several tissues, including but not limited to lung, kidney, liver, gut, and immune cells. The question has been raised on whether DPP4 modulation or inhibition may prevent infection and/or progression of the COVID-19. A docked complex model of the SARS-CoV-2 spike glycoprotein and DPP4 has been proposed, showing a large interface between the proteins and proposing close similarity with other coronaviruses using DPP4 as functional receptor. In absence of experimental validation, these data should be interpreted with caution. Nevertheless, this observation may rise the question on whether DPP4 is directly involved in SARS-CoV-2 cell adhesion/virulence, and whether DPP4 inhibition might be a therapeutic strategy for preventing infection. Although a direct involvement of DPP4 in SARS-CoV-2 infection needs to be clarified, there is also evidence suggesting that DPP4 inhibitors modulate inflammation and exert anti-fibrotic activity. These properties may be of potential use for halting progression to the hyperinflammatory state associated with severe COVID-19. Taken together these findings may suggest a potential role for DPP4 inhibition or modulation in one or more steps of COVID-19 immunopathogenesis.

The effects of canagliflozin compared to sitagliptin on cardiorespiratory fitness in type 2 diabetes mellitus and heart failure with reduced ejection fraction: The CANA-HF study

BACKGROUND

Canagliflozin reduces hospitalizations for heart failure (HF) in type 2 diabetes mellitus (T2DM). Its effect on cardiorespiratory fitness and cardiac function in patients with established HF with reduced ejection fraction (HFrEF) is unknown.

METHODS

We conducted a double-blind randomized controlled trial of canagliflozin 100 mg or sitagliptin 100 mg daily for 12 weeks in 88 patients, and measured peak oxygen consumption (VO₂ ) and minute ventilation/carbon dioxide production (VE/VCO₂ ) slope (co-primary endpoints for repeated measure ANOVA time_x_group interaction), lean peak VO₂ , ventilatory anaerobic threshold (VAT), cardiac function and quality of life (ie, Minnesota Living with Heart Failure Questionnaire [MLHFQ]), at baseline and 12-week follow-up.

RESULTS

The study was terminated early due to the new guidelines recommending canagliflozin over sitagliptin in HF: 17 patients were assigned to canagliflozin and 19 to sitagliptin, total of 36 patients. There were no significant changes in peak VO₂ and VE/VCO₂ slope between the two groups (P = .083 and P = .98, respectively). Canagliflozin improved lean peak VO₂ (+2.4 mL kg_LM^-1 min^-1 , P = .036), VAT (+1.5 mL kg^-1 min^-1 , P = .012) and VO₂ matched for respiratory exchange ratio (+2.4 mL Kg^-1 min^-1 , P = .002) compared to sitagliptin. Canagliflozin also reduced MLHFQ score (-12.1, P = .018).

CONCLUSIONS

In this small and short-term study of patients with T2DM and HFrEF, interrupted early after only 36 patients, canagliflozin did not improve the primary endpoints of peak VO₂ or VE/VCO₂ slope compared to sitagliptin, while showing favourable trends observed on several additional surrogate endpoints such as lean peak VO₂ , VAT and quality of life.

Dipeptidyl-peptidase IV inhibitors (DPP4i)-associated bullous pemphigoid: Estimating the clinical profile and exploring intraclass differences

Data regarding the clinical characteristics of patients with dipeptidyl-peptidase IV inhibitors (DPP4i)-associated BP is inconclusive. We aimed to characterize the clinical features of patients with DPP4i-associated BP, and to assess whether there are phenotypic differences associated with different agents belonging to the DPP4i class. A retrospective prevalence study was performed, including all consecutive patients diagnosed with BP throughout the years 2000 to 2019. The study included 397 patients with BP, of whom 58 (14.6%) were DPP4i-associated. Compared to other patients with BP, patients with DPP4i-associated BP had a more prominent male preponderance (60.3% vs 41.0%; P = .006), presented more frequently with extensive disease (60.3% vs 46.3%; P = .049), had greater truncal (96.6% vs 85.5%; P = .019) and cephalic (51.7% vs 33.6%; P = .008) involvement, and had less frequent peripheral eosinophilia (25.9% vs 51.9%; P < .001). Compared to patients with vildagliptin-associated BP, those with linagliptin-associated BP were managed by higher dosage of systemic corticosteroids in order to achieve disease control (prednisone > 1 mg/kg: 68.2% vs 40.0%; P = .046). In conclusion, DPP4i-associated BP seems to have a unique clinical profile characterized by male predominance, extensive disease, truncal and cephalic involvement, and less peripheral eosinophilia. Linagliptin may be associated with a harder course necessitating more aggressive therapy.

Dipeptidyl peptidase-4 (DPP4) inhibition in COVID-19

AIMS

SARS-CoV-2 causes severe respiratory syndrome (COVID-19) with high mortality due to a direct cytotoxic viral effect and a severe systemic inflammation. We are herein discussing a possible novel therapeutic tool for COVID-19.

METHODS

Virus binds to the cell surface receptor ACE2; indeed, recent evidences suggested that SARS-CoV-2 may be using as co-receptor, when entering the cells, the same one used by MERS-Co-V, namely the DPP4/CD26 receptor. The aforementioned observation underlined that mechanism of cell entry is supposedly similar among different coronavirus, that the co-expression of ACE2 and DPP4/CD26 could identify those cells targeted by different human coronaviruses and that clinical complications may be similar.

RESULTS

The DPP4 family/system was implicated in various physiological processes and diseases of the immune system, and DPP4/CD26 is variously expressed on epithelia and endothelia of the systemic vasculature, lung, kidney, small intestine and heart. In particular, DPP4 distribution in the human respiratory tract may facilitate the entrance of the virus into the airway tract itself and could contribute to the development of cytokine storm and immunopathology in causing fatal COVID-19 pneumonia.

CONCLUSIONS

The use of DPP4 inhibitors, such as gliptins, in patients with COVID-19 with, or even without, type 2 diabetes, may offer a simple way to reduce the virus entry and replication into the airways and to hamper the sustained cytokine storm and inflammation within the lung in patients diagnosed with COVID-19 infection.

Potential Benefits and Harms of Novel Antidiabetic Drugs During COVID-19 Crisis

Patients with diabetes have been reported to have enhanced susceptibility to severe or fatal COVID-19 infections, including a high risk of being admitted to intensive care units with respiratory failure and septic complications. Given the global prevalence of diabetes, affecting over 450 million people worldwide and still on the rise, the emerging COVID-19 crisis poses a serious threat to an extremely large vulnerable population. However, the broad heterogeneity and complexity of this dysmetabolic condition, with reference to etiologic mechanisms, degree of glycemic derangement and comorbid associations, along with the extensive sexual dimorphism in immune responses, can hamper any patient generalization. Even more relevant, and irrespective of glucose-lowering activities, DPP4 inhibitors and GLP1 receptor agonists may have a favorable impact on the modulation of viral entry and overproduction of inflammatory cytokines during COVID-19 infection, although current evidence is limited and not univocal. Conversely, SGLT2 inhibitors may increase the likelihood of COVID-19-related ketoacidosis decompensation among patients with severe insulin deficiency. Mindful of their widespread popularity in the management of diabetes, addressing potential benefits and harms of novel antidiabetic drugs to clinical prognosis at the time of a COVID-19 pandemic deserves careful consideration.

Genetic variants associated with glycemic response to treatment with dipeptidylpeptidase 4 inhibitors

Aim: We examined associations of eight SNPs in/near seven candidate genes with glycemic response to 6 month treatment with DPP4 inhibitors. Patients & methods: 206 patients with type 2 diabetes (116 men and 90 women) were treated with sitagliptin or vildagliptin (both 100 mg/day) in combination with metformin or metformin/sulphonylurea over 6 months, and the reduction in glycated hemoglobin (HbA1c) was measured. Results: Rs6923761 in GLP1R was significantly associated with a reduction in HbA1c (adjusted p = 0.006). Homozygotes for the minor A allele had smaller reduction in HbA1c by 0.4% (4 mmol/mol) than the G allele carriers (p = 0.016). Conclusion: The missense variant rs6923761 in the GLP1R gene was associated with a smaller glycemic response to 6 month gliptin therapy in diabetic patients of central European origin.

Corticotroph adenoma and pituitary fungal infection: a rare association

SUMMARY

Pituitary infections, particularly with fungus, are rare disorders that usually occur in immunocompromised patients. Cushing's syndrome predisposes patients to infectious diseases due to their immunosuppression status. We report the case of a 55-year-old woman, working as a poultry farmer, who developed intense headache, palpebral ptosis, anisocoria, prostration and psychomotor agitation 9 months after initial diabetes mellitus diagnosis. Cranioencephalic CT scan showed a pituitary lesion with bleeding, suggesting pituitary apoplexy. Patient underwent transsphenoidal surgery and the neuropathologic study indicated a corticotroph adenoma with apoplexy and fungal infection. Patient had no preoperative Cushing's syndrome diagnosis. She was evaluated by a multidisciplinary team who decided not to administer anti-fungal treatment. The reported case shows a rare association between a corticotroph adenoma and a pituitary fungal infection. The possible contributing factors were hypercortisolism, uncontrolled diabetes and professional activity. Transsphenoidal surgery is advocated in these infections; however, anti-fungal therapy is still controversial.

LEARNING POINTS

Pituitary infections are rare disorders caused by bacterial, viral, fungal and parasitic infections. Pituitary fungal infections usually occur in immunocompromised patients. Cushing's syndrome, as immunosuppression factor, predisposes patients to infectious diseases, including fungal infections. Diagnosis of pituitary fungal infection is often achieved during histopathological investigation. Treatment with systemic anti-fungal drugs is controversial. Endocrine evaluation is recommended at the time of initial presentation of pituitary manifestations.

The protective role of DPP4 inhibitors in atherosclerosis

Diabetes is a chronic non-communicable disease whose incidence continues to grow rapidly, and it is one of the most serious and critical public health problems. Diabetes complications, especially atherosclerosis-related chronic vascular complications, are a serious threat to human life and health. Growing evidence suggests that dipeptidyl peptidase 4 (DPP4) inhibitors, beyond their role in improving glycemic control, are helpful in ameliorating endothelial dysfunction in humans and animal models of T2DM. In fact, DPP4 inhibitors have been shown by successive studies to play a protective effect against vascular complications. On one hand, in addition to their hypoglycemic effects, DPP4 inhibitors participate in the control of atherosclerotic risk factors by regulating blood lipids and lowering blood pressure. On the other hand, DPP4 inhibitors exert anti-atherosclerotic effects directly through multiple mechanisms, including improving endothelial cell dysfunction, increasing circulating endothelial progenitor cell (EPCs) levels, regulating mononuclear macrophages and smooth muscle cells, inhibiting inflammation and oxidative stress and improving plaque instability. Herein, we review the beneficial roles of DPP4 inhibitors in atherosclerosis as detailed.

Glucocorticoids mobilize macrophages by transcriptionally up-regulating the exopeptidase DPP4

Glucocorticoids are potent endogenous anti-inflammatory molecules, and their cognate receptor, glucocorticoid receptor (GR), is expressed in nearly all immune cells. Macrophages are heterogeneous immune cells having a central role in both tissue homeostasis and inflammation and also play a role in the pathogenesis of some inflammatory diseases. Paradoxically, glucocorticoids have only a limited efficacy in controlling the resolution of these macrophage-related diseases. Here, we report that the transcriptomes of monocyte-like THP-1 cells and macrophage-like THP-1 cells (THP1-MΦ) have largely conserved gene expression patterns. In contrast, the differentiation to THP1-MΦ significantly altered the sensitivity of gene transcription to glucocorticoids. Among glucocorticoid-regulated genes, we identified the exopeptidase dipeptidyl peptidase-4 (DPP4) as a critical glucocorticoid-responsive gene in THP1-MΦ. We found that GR directly induces DPP4 gene expression by binding to two glucocorticoid-responsive elements (GREs) within the DPP4 promoter. Additionally, we show that glucocorticoid-induced DPP4 expression is blocked by the GR antagonist RU-486 and by GR siRNA transfection and that DPP4 enzyme activity is reduced by DPP4 inhibitors. Of note, glucocorticoids highly stimulated macrophage mobility; unexpectedly, DPP4 mediated the glucocorticoid-induced macrophage migration, and siRNA-mediated knockdowns of GR and DPP4 blocked dexamethasone-induced THP1-MΦ migration. Moreover, glucocorticoid-induced DPP4 activation was also observed in proinflammatory M1-polarized murine macrophages, as well as peritoneal macrophages, and was associated with increased macrophage migration. Our results indicate that glucocorticoids directly up-regulate DPP4 expression and thereby induce migration in macrophages, potentially explaining why glucocorticoid therapy is less effective in controlling macrophage-dominated inflammatory disorders.

Glucose-lowering drugs and heart failure: implications of recent cardiovascular outcome trials in type 2 diabetes

Heart failure (HF) is common in Type-2 diabetes mellitus (T2DM), and viceversa, leading to a mutual impact on prognosis. Knowledge about this complex interplay has dramatically changed recently, due to development of new glucose-lowering drugs, and to specific FDA and EMA Guidance mandating to perform cardiovascular outcome trials (CVOTs), aimed at establishing cardiovascular safety, for new anti-diabetic treatments before they enter the market. Such CVOTs have demonstrated that the effects of the new antidiabetic drugs on the mutual interactions between T2DM and HF may develop across different phases:Results of such trials can be summarized as: (a) all different classes of novel glucose-lowering drugs have good cardiovascular safety profile; (b) with respect to HF, DPP4 inhibitors might tend to increase risk; (c) sodium-glucose co-transporter 2 inhibitors (SGTLi), significantly reduce it; (d) glucagon-like peptide 1 receptor agonists (GLP1) tend to be neutral. These CVOTs data have led to guideline recommendations indicating appropriate therapy to T2DM patients with HF not at glycemic control target with metformin therapy.

Therapeutic Strategies for Alzheimer's Disease in the View of Diabetes Mellitus

Recently, Alzheimer's disease (AD) is understood as "diabetes of the brain" or "type 3 diabetes." Recent clinical trials of anti-amyloid β-protein (Aβ) therapies have not proved to be successful. Thus, glucose-insulin metabolism in the brain is thought to be an alternative therapeutic target. Various types of antidiabetic drugs such as insulin, thiazolidinediones, dipeptidyl peptidase-4 (DPP4) inhibitors, glucagon-like peptide-1 (GLP-1) agonists, biguanides, and others have been reported to be effective on cognitive impairment in animal models and patients with DM or AD. Here, recent reports are reviewed. While we identified apomorphine (APO) as a novel drug that promoted intracellular Aβ degradation and improved memory function in an AD mouse model, more recently, we have revealed that APO treatment improves neuronal insulin resistance and activates insulin-degrading enzyme (IDE), a major Aβ-degrading enzyme. In this context, recovery of impaired insulin signaling in AD neurons may be a promising therapeutic strategy for AD dementia.

Dipeptidyl peptidase 4 inhibitors as novel agents in improving survival in diabetic patients with colorectal cancer and lung cancer: A Surveillance Epidemiology and Endpoint Research Medicare study

Background

Dipeptidyl peptidase 4 (DPP4) is a cell surface protein that can act as a tumor suppressor or activator, depending upon the level of expression and interaction with the microenvironment and chemokines. DPP4 inhibitors are used to treat diabetes.

Methods

We conducted this Surveillance Epidemiology and Endpoint Research‐Medicare database study to evaluate the role of DPP4 inhibitors on the overall survival (OS) of diabetic patients diagnosed with colorectal (CRC) and lung cancers.

Results

Diabetic patients with CRC or lung cancer who were treated with DPP4 inhibitors exhibited a statistically significant survival advantage (hazard ratio [HR] of 0.89; CI: 0.82‐0.97, P = 0.007) that remained significant after controlling for all other confounders. When DPP4 inhibitors were used in combination of metformin which is known to suppress cancer, the survival advantage was even more pronounced (HR of 0.83; CI: 0.77‐0.90, P < 0.0001). Data were then analyzed separately for two cancer types. In the CRC‐only cohort, the use of DPP4 inhibitors alone had a positive trend but did not meet statistically significant threshold (HR of 0.87; CI: 0.75‐1.00, P = 0.055), while the combined use of DPP4 inhibitors and metformin was associated with statistically significant survival advantage (HR of 0.77; CI: 0.67‐0.89, P = 0.003). Similarly, for the lung cancer cohort, use of DPP4 alone was not found to be statistically significant (HR of 0.93; CI: 0.83‐1.03, P = 0.153), whereas lung cancer patients treated with the combination of DPP4 inhibitors and metformin showed statistically significant survival advantage (HR of 0.88; CI: 0.80‐0.97, P = 0.010).

Conclusions

DPP4 inhibition in CRC and lung cancer is associated with improved OS, which possibly may be due to the effect of DPP4 inhibition on immunoregulation of cancer.

Therapeutic Experience of Saxagliptin as First Add-on after Metformin in Indian Type 2 Diabetes Patients: A Non-interventional, Prospective, Observational Study (ONTARGET-INDIA)

INTRODUCTION

Dipeptidyl peptidase 4 (DPP4) inhibitors are widely used in type 2 diabetes mellitus (T2DM) patients but the data available in existing clinical trial programmes on DPP4 inhibitors include limited number of patients from India. Hence, this study attempted to understand usage, efficacy and safety of saxagliptin as first add-on after metformin in Indians with T2DM.

METHODOLOGY

It was a multicenter, prospective, non-interventional and observational study planned to enrol T2DM patients who were inadequately controlled with metformin alone and had been recently (i.e., within past 15 days) prescribed saxagliptin as an add-on to metformin. Type 1 diabetes mellitus, use of glucose lowering drugs apart from metformin or saxagliptin, pregnancy, lactation, and medical condition, which could interfere with safe completion of the study were excluded.

RESULTS

A total of 1109 participants (658 men and 451 women) with mean ± SD age of 51.17 ± 11.85 years were enrolled from 50 centres throughout India. Significant reduction was observed in mean ± SD change of HbA1c as - 0.86% ± 1.76 from baseline to after 3 months of therapy (P < 0.0001). The quality of life assessed by World Health Organization Quality of Life-BREF (WHOQOL-BREF) questionnaire was reported to be "good" or "neither good nor bad" by majority of the participants at baseline and after 3 months of treatment. A total of 15 adverse events (AEs) were reported in the study, however, no serious adverse event (SAE) occurred during the study. All AEs were of mild intensity and did not require any intervention.

CONCLUSION

Overall, saxagliptin in combination with metformin was generally well tolerated in Indian T2DM patients and new safety event identified is an increased risk of hospitalisation in heart failure patients. This study is also registered on Clinicaltrials.gov (NCT02588859).

Paraganglioma presenting as stress cardiomyopathy: case report and literature review

Pheochromocytoma/paraganglioma (PPGL) are neuroendocrine tumors that can secrete catecholamines. The authors describe a challenging case who presented as stress cardiomyopathy and myocardial infarction (MI). A 76-year-old man, with a medical history of Parkinson's disease, type 2 diabetes mellitus, hypertension, dyslipidaemia and a previous inferior MI in 2001, presented to the emergency department due to chest pain, headaches and vomiting. He also reported worsening blood glucose levels and increasing constipation over the preceding weeks. BP was 185/89 mmHg (no other relevant findings). EKG had ST segment depression in leads V2-V6, T troponin was 600 ng/L (<14) and the echocardiogram showed left ventricular hypokinesia with mildly compromised systolic function. Nevertheless, he rapidly progressed to severe biventricular dysfunction. Coronary angiogram showed a 90% anterior descendent coronary artery occlusion (already present in 2001), which was treated with angioplasty/stenting. In the following days, a very labile BP profile and unexplained sinus tachycardia episodes were observed. Because of sustained severe constipation, the patient underwent an abdominal CT that revealed a retroperitoneal, heterogeneous, hypervascular mass on the right (62 × 35 mm), most likely a paraganglioma. Urinary metanephrines were increased several fold. 68Ga-DOTANOC PET-CT scan showed increased uptake in the abdominal mass (no evidence of disease elsewhere). He was started on a calcium-channel blocker and alpha blockade and underwent surgery with no major complications. Eight months after surgery, the patient has no evidence of disease. Genetic testing was negative for known germline mutations. This was a challenging diagnosis, but it was essential for adequate cardiovascular stabilization and to reduce further morbidity. Learning points: PPGL frequently produces catecholamines and can manifest with several cardiovascular syndromes, including stress cardiomyopathy and myocardial infarction. Even in the presence of coronary artery disease (CAD), PPGL should be suspected if signs or symptoms attributed to catecholamine excess are present (in this case, high blood pressure, worsening hyperglycaemia and constipation). Establishing the correct diagnosis is important for adequate treatment choice. Inodilators and mechanical support might be preferable options (if available) for cardiovascular stabilization prior to alpha blockade and surgery. Laboratory interference should be suspected irrespective of metanephrine levels, especially in the context of treated Parkinson's disease.

Utilising a milk-based meal replacement programme in a bariatric patient with poorly controlled type 2 diabetes mellitus

A 45-year-old man with poorly controlled type 2 diabetes (T2DM) (HbA1c 87 mmol/mol) despite 100 units of insulin per day and severe obesity (BMI 40.2 kg/m2) was referred for bariatric intervention. He declined bariatric surgery or GLP1 agonist therapy. Initially, his glycaemic control improved with dietary modification and better adherence to insulin therapy, but he gained weight. We started a low-energy liquid diet, with 2.2 L of semi-skimmed milk (equivalent to 1012 kcal) per day for 8 weeks (along with micronutrient, salt and fibre supplementation) followed by 16 weeks of phased reintroduction of a normal diet. His insulin was stopped within a week of starting this programme, and over 6 months, he lost 20.6 kg and his HbA1c normalised. However, 1 year later, despite further weight loss, his HbA1c deteriorated dramatically, requiring introduction of linagliptin and canagliflozin, with good response. Five years after initial presentation, his BMI remains elevated but improved at 35.5 kg/m2 and his glycaemic control is excellent with a HbA1c of 50 mmol/mol and he is off insulin therapy. Whether semi-skimmed milk is a safe, effective substrate for carefully selected patients with severe obesity complicated by T2DM remains to be determined. Such patients would need frequent monitoring by an experienced multidisciplinary team. Learning points: Meal replacement programmes are an emerging therapeutic strategy to allow severely obese type 2 diabetes patients to achieve clinically impactful weight loss. Using semi-skimmed milk as a meal replacement substrate might be less costly than commercially available programmes, but is likely to require intensive multidisciplinary bariatric clinical follow-up. For severely obese adults with poor diabetes control who decline bariatric surgery or GLP1 agonist therapy, a milk-based meal replacement programme may be an option. Milk-based meal replacement in patients with insulin requiring type 2 diabetes causes rapid and profound reductions in insulin requirements, so rigorous monitoring of glucose levels by patients and their clinicians is necessary. In carefully selected and adequately monitored patients, the response to oral antidiabetic medications may help to differentiate between absolute and relative insulin deficiency.

Possible mechanisms of direct cardiovascular impact of GLP-1 agonists and DPP4 inhibitors

Diabetes mellitus is a leading cause of cardiovascular morbidity and mortality worldwide. Traditional antidiabetic therapies targeting hyperglycemia reduce diabetic microvascular complications but have minor effects on macrovascular complications, including cardiovascular disease. Instead, cardiovascular complications are improved by antidiabetic medications (metformin) and other therapies (statins, antihypertensive medications) ameliorating insulin resistance and other associated metabolic abnormalities. Novel classes of antidiabetic drugs have proven efficacious in improving glycemia, while at the same time exert beneficial effects on pathophysiologic mechanisms of diabetes-related cardiovascular disease. In the present review, we will present current evidence of the cardiovascular effects of two new classes of antidiabetic medications, glucagon-like peptide 1 (GLP-1) agonists and dipeptidyl peptidase-4 (DPP4) inhibitors, focusing from mechanistic preclinical and clinical investigation to late-phase clinical testing.

Diabetes pharmacotherapy and effects on the musculoskeletal system

Persons with type 1 or type 2 diabetes have a significantly higher fracture risk than age-matched persons without diabetes, attributed to disease-specific deficits in the microarchitecture and material properties of bone tissue. Therefore, independent effects of diabetes drugs on skeletal integrity are vitally important. Studies of incretin-based therapies have shown divergent effects of different agents on fracture risk, including detrimental, beneficial, and neutral effects. The sulfonylurea class of drugs, owing to its hypoglycemic potential, is thought to amplify the risk of fall-related fractures, particularly in the elderly. Other agents such as the biguanides may, in fact, be osteo-anabolic. In contrast, despite similarly expected anabolic properties of insulin, data suggests that insulin pharmacotherapy itself, particularly in type 2 diabetes, may be a risk factor for fracture, negatively associated with determinants of bone quality and bone strength. Finally, sodium-dependent glucose co-transporter 2 inhibitors have been associated with an increased risk of atypical fractures in select populations, and possibly with an increase in lower extremity amputation with specific SGLT2I drugs. The role of skeletal muscle, as a potential mediator and determinant of bone quality, is also a relevant area of exploration. Currently, data regarding the impact of glucose lowering medications on diabetes-related muscle atrophy is more limited, although preclinical studies suggest that various hypoglycemic agents may have either aggravating (sulfonylureas, glinides) or repairing (thiazolidinediones, biguanides, incretins) effects on skeletal muscle atrophy, thereby influencing bone quality. Hence, the therapeutic efficacy of each hypoglycemic agent must also be evaluated in light of its impact, alone or in combination, on musculoskeletal health, when determining an individualized treatment approach. Moreover, the effect of newer medications (potentially seeking expanded clinical indication into the pediatric age range) on the growing skeleton is largely unknown. Herein, we review the available literature regarding effects of diabetes pharmacotherapy, by drug class and/or by clinical indication, on the musculoskeletal health of persons with diabetes.

Safety and Efficacy of DPP4 Inhibitor and Basal Insulin in Type 2 Diabetes: An Updated Review and Challenging Clinical Scenarios

The safety and efficacy of dipeptidyl peptidase-4 (DPP4) inhibitors as monotherapy or in combination with other oral antidiabetic agents or basal insulin are well established. DPP4 inhibitors stimulate glucose-dependent insulin secretion and inhibit glucagon production. As monotherapy, they reduce the hemoglobin A1c level by about 0.6-0.8%. The addition of a DPP4 inhibitor to basal insulin is an attractive option, because they lower both postprandial and fasting plasma glucose concentrations without increasing the risk of hypoglycemia or weight gain. The present review summarizes the extensive evidence on the combination therapy of DPP4 inhibitors and insulin-based regimens in patients with type 2 diabetes. We focus our discussion on challenging clinical scenarios including patients with chronic renal impairment, elderly persons and hospitalized patients. The evidence indicates that these drugs are highly effective and safe in the elderly and in the presence of mild, moderate and severe renal failure improving glycemic control with low risk of hypoglycemia. In addition, several randomized-controlled trials have shown that the use of DPP4 inhibitors in combination with basal insulin represents an alternative to the basal-bolus insulin regimen in hospitalized patients with type 2 diabetes.

The place of gliclazide MR in the evolving type 2 diabetes landscape: A comparison with other sulfonylureas and newer oral antihyperglycemic agents

The sulfonylureas are effective oral glucose-lowering agents with a long history of clinical use. While all have the same general mechanism of action, their pharmacokinetic properties are influenced by factors such as dosage, rate of absorption, duration of action, route of elimination, tissue specificity, and binding affinity for pancreatic β-cell receptor. The result is a class of agents with similar HbA1c-lowering efficacy, but well-documented differences in terms of effects on hypoglycemia, and cardiovascular and renal safety. This review examines the differences between currently available sulfonylureas with a focus on how gliclazide modified release (MR) differs from other members of this class and from newer oral antihyperglycemic agents in the form of dipeptidyl peptidase-4 (DPP4) and sodium- glucose cotransporter 2 (SGLT2) inhibitors. The first part focuses on major outcome trials that have been conducted with the sulfonylureas and new oral agents. Consideration is then given to factors important for day-to-day prescribing including efficacy and durability, weight changes, hypoglycemia, renal effects and cost. Based on current evidence, third-generation sulfonylureas such as gliclazide MR possess many of the properties desired of a type 2 diabetes drug including high glucose-lowering efficacy, once-daily oral administration, few side effects other than mild hypoglycemia, and cardiovascular safety.

Cardioprotection of dapagliflozin and vildagliptin in rats with cardiac ischemia-reperfusion injury

Sodium-glucose cotransporter 2 inhibitor (SGLT2-i) effects on cardiac ischemia/reperfusion (I/R) injury are unclear. Unlike SGLT2-i, dipeptidyl peptidase 4 inhibitors (DPP4-i) have shown effective cardioprotection in cardiac I/R injury. We aimed to investigate whether SGLT2-i reduces myocardial dysfunction and myocardial injury to a greater extent than DPP4-i in obese insulin-resistant rats with/without cardiac I/R injury. The high-fat (HF) diet-induced obese insulin-resistant rats were divided into 4 groups and received the following treatments for 28 days: vehicle (HFV); vildagliptin at a dosage of 3 mg/kg/day (HFVil); dapagliflozin at a dosage of 1 mg/kg/day (HFDa) and combination drugs (HFDaVil). At the end, I/R injury was induced by a 30-min left anterior descending coronary occlusion and 120-min reperfusion. Dapagliflozin showed a greater efficacy than vildagliptin in improving the metabolic impairments, low frequency/high frequency (LF/HF) ratio, systolic blood pressure and left ventricular (LV) function in comparison to HFV rats. In cardiac I/R injury, dapagliflozin had a greater efficacy than vildagiptin in decreasing mitochondrial DRP1, cleaved caspase 3, LV dysfunction and infarct size in comparison to HFV rats. However, the combined therapy showed the greatest efficacy in attenuating LV dysfunction, mitochondrial DRP1 and infarct size in comparison to HFV rats. In conclusion, dapagliflozin has a more pronounced effect than vildagliptin in obese insulin-resistant rats for the improvement of LV function. In rats with cardiac I/R injury, although dapagliflozin had a greater efficacy on cardioprotection than vildagliptin, the combined therapy exerted the highest cardioprotective effects potentially by reducing mitochondrial fission.

A Randomized Controlled Study Comparing a DPP4 Inhibitor (Linagliptin) and Basal Insulin (Glargine) in Patients With Type 2 Diabetes in Long-term Care and Skilled Nursing Facilities: Linagliptin-LTC Trial

OBJECTIVES

Safe and easily implemented treatment regimens are needed for the management of patients with type 2 diabetes mellitus (T2DM) in long-term care (LTC) and skilled nursing facilities.

DESIGN

This 6-month open-label randomized controlled trial compared the efficacy and safety of a DPP4 inhibitor (linagliptin) and basal insulin (glargine) in LTC residents with T2DM.

SETTINGS

Three LTC institutions affiliated with a community safety-net hospital, US Department of Veterans Affairs and Emory Healthcare System in Atlanta, Georgia.

PARTICIPANTS

A total of 140 residents with T2DM treated with oral antidiabetic agents or low-dose insulin (≤0.1 U/kg/d), with fasting or premeal blood glucose (BG) > 180 mg/dL and/or HbA1c >7.5%.

INTERVENTION

Baseline antidiabetic therapy, except metformin, was discontinued on trial entry. Residents were treated with linagliptin 5 mg/d (n = 67) or glargine at a starting dose of 0.1 U/kg/d (n = 73). Both groups received supplemental rapid-acting insulin before meals for BG > 200 mg/dL.

MEASUREMENTS

Primary outcome was mean difference in daily BG between groups. Main secondary endpoints included differences in frequency of hypoglycemia, glycosylated hemoglobin (HbA1c), complications, emergency department visits, and hospital transfers.

RESULTS

Treatment with linagliptin resulted in no significant differences in mean daily BG (146 ± 34 mg/dL vs. 157 ± 36 mg/dL, P = .07) compared to glargine. Linagliptin treatment resulted in fewer mild hypoglycemic events <70 mg/dL (3% vs. 37%, P < .001), but there were no differences in BG < 54 mg/dL (P = .06) or <40 mg/dL (P = .05) compared to glargine. There were no significant between-group differences in HbA1c, length of stay, complications, emergency department visits, or hospitalizations.

CONCLUSION

Treatment with linagliptin resulted in noninferior glycemic control and in significantly lower risk of hypoglycemia compared to insulin glargine in long-term care and skilled nursing facility residents with type 2 diabetes.

Diabetes Medications and Cardiovascular Outcomes in Type 2 Diabetes

INTRODUCTION

Patients with type 2 diabetes have an increased risk of developing adverse cardiovascular (CV) outcomes. The evidence relating to the effects of glucose-lowering medications on CV outcomes is of variable quality and there are numerous trials ongoing.

RESULTS

In this review, we summarise the available literature on CV outcomes of the following diabetes treatments: metformin, the sulfonylureas, acarbose, glucagon-like peptide 1 (GLP1) receptor agonists, dipeptidyl peptidase-4 inhibitors (DPP4i), sodium-glucose co-transporter 2 inhibitors (SGLT2i), thiazolidinediones (TZDs) and insulin.

CONCLUSIONS

Insulin is required if glucose levels are very high. Otherwise, metformin, acarbose, some GLP1 receptor agonists and one SGLT2i appear beneficial for CV outcomes.

Boning up on DPP4, DPP4 substrates, and DPP4-adipokine interactions: Logical reasoning and known facts about bone related effects of DPP4 inhibitors

Dipeptidyl peptidase 4 (DPP4) is a conserved exopeptidase with an important function in protein regulation. The activity of DPP4, an enzyme which can either be anchored to the plasma membrane or circulate free in the extracellular compartment, affects the glucose metabolism, cellular signaling, migration and differentiation, oxidative stress and the immune system. DPP4 is also expressed on the surface of osteoblasts, osteoclasts and osteocytes, and was found to play a role in collagen metabolism. Many substrates of DPP4 have an established role in bone metabolism, among which are incretins, gastrointestinal peptides and neuropeptides. In general, their effects favor bone formation, but some effects are complex and have not been completely elucidated. DPP4 and some of its substrates are known to interact with adipokines, playing an essential role in the energy metabolism. The prolongation of the half-life of incretins through DPP4 inhibition led to the development of these inhibitors to improve glucose tolerance in diabetes. Current literature indicates that the inhibition of DPP4 activity might also result in a beneficial effect on the bone metabolism, but the long-term effect of DPP4 inhibition on fracture outcome has not been entirely established. Diabetic as well as postmenopausal osteoporosis is associated with an increased activity of DPP4, as well as a shift in the expression levels of DPP4 substrates, their receptors, and adipokines. The interactions between these factors and their relationship in bone metabolism are therefore an interesting field of study.