Improved glucose regulation in type 2 diabetic patients with DPP-4 inhibitors: focus on alpha and beta cell function and lipid metabolism

Efficacy and Safety of Alogliptin-Pioglitazone Combination for Type 2 Diabetes Mellitus Poorly Controlled with Metformin: A Multicenter, Double-Blind Randomized Trial

BACKGRUOUND

Guidelines for switching to triple combination therapy directly after monotherapy failure are limited. This study investigated the efficacy, long-term sustainability, and safety of either mono or dual add-on therapy using alogliptin and pioglitazone for patients with type 2 diabetes mellitus (T2DM) who did not achieve their target glycemic range with metformin monotherapy.

METHODS

The Practical Evidence of Antidiabetic Combination Therapy in Korea (PEAK) was a multicenter, placebo-controlled, double-blind, randomized trial. A total of 214 participants were randomized to receive alogliptin+pioglitazone (Alo+Pio group, n=70), alogliptin (Alo group, n=75), or pioglitazone (Pio group, n=69). The primary outcome was the difference in glycosylated hemoglobin (HbA1c) levels between the three groups at baseline to 24 weeks. For durability, the achievement of HbA1c levels <7% and <6.5% was compared in each group. The number of adverse events was investigated for safety.

RESULTS

After 24 weeks of treatment, the change of HbA1c in the Alo+Pio, Alo, and Pio groups were -1.38%±0.08%, -1.03%±0.08%, and -0.84%±0.08%, respectively. The Alo+Pio group had significantly lower HbA1c levels than the other groups (P=0.0063, P<0.0001) and had a higher proportion of patients with target HbA1c achievement. In addition, insulin sensitivity and β-cell function, lipid profiles, and other metabolic indicators were also improved. There were no significant safety issues in patients treated with triple combination therapy.

CONCLUSION

Early combination triple therapy showed better efficacy and durability than the single add-on (dual) therapy. Therefore, combination therapy with metformin, alogliptin, and pioglitazone is a valuable early treatment option for T2DM poorly controlled with metformin monotherapy.

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.

Thiazolidinedione as a Promising Medicinal Scaffold for the Treatment of Type 2 Diabetes

BACKGROUND

Thiazolidinediones, also known as glitazones, are considered as biologically active scaffold and a well-established class of anti-diabetic agents for the treatment of type 2 diabetes mellitus. Thiazolidinediones act by reducing insulin resistance through elevated peripheral glucose disposal and glucose production. These molecules activate peroxisome proliferated activated receptor (PPARγ), one of the sub-types of PPARs, and a diverse group of its hybrid have also shown numerous therapeutic activities along with antidiabetic activity.

OBJECTIVE

The objective of this review was to collect and summarize the research related to the medicinal potential, structure-activity relationship and safety aspects of thiazolidinedione analogues designed and investigated in type 2 diabetes during the last two decades.

METHODS

The mentioned objective was achieved by collecting and reviewing the research manuscripts, review articles, and patents from PubMed, Science Direct, Embase, google scholar and journals related to the topic from different publishers like Wiley, Springer, Elsevier, Taylor and Francis, Indian and International government patent sites etc. Results: The thiazolidinedione scaffold has been a focus of research in the design and synthesis of novel derivatives for the management of type 2 diabetes, specifically in the case of insulin resistance. The complications like fluid retention, idiosyncratic hepatotoxicity, weight gain and congestive heart failure in the case of trosiglitazone, and pioglitazone have restricted their use. The newer analogues have been synthesized by different research groups to attain better efficacy and less side effects.

CONCLUSION

Thus, the potential of thiazolidinediones in terms of their chemical evolution, action on nuclear receptors, aldose reductase and free fatty acid receptor 1 is well established. The newer TZD analogues with better safety profiles and tolerability will soon be available in the market for common use without further delay.

Pharmacological and Clinical Studies of Medicinal Plants That Inhibit Dipeptidyl Peptidase-IV

Dipeptidyl peptidase IV (DPP-IV) is an enzyme responsible for the degradation of the incretin hormone glucagon-like peptide-1 (GLP-1). DPP-IV plays a significant role in regulating blood glucose levels by modulating the activity of GLP-1. In the context of diabetes, DPP-IV inhibitors effectively block the activity of DPP-IV, hence mitigating the degradation of GLP-1. This, in turn, leads to an extension of GLP-1's duration of action, prolongs gastric emptying, enhances insulin sensitivity, and ultimately results in the reduction of blood glucose levels. Nonetheless, reported adverse events of DPP-IV inhibitors on T2DM patients make it essential to understand the activity and mechanism of these drugs, particularly viewed from the perspective of finding the effective and safe add-on medicinal plants, to be implemented in clinical practice. This review is intended to bring forth a thorough overview of plants that work by reducing DPP-IV activity, from computational technique, enzymatic study, animal experiments, and studies in humans. The articles were searched on PubMed using "Plants", "DPP-IV", "DPP-IV inhibitor", "GLP-1", "Type 2 diabetes", "diabetes", "in silico", "in vitro", "in vivo", "studies in human", "clinical study" as the query words, and filtered for ten years of publication period. Eighteen plants showed inhibition against DPP-IV as proven by in silico, in vitro, and in vivo studies; however, only ten plants were reported for efficacy in clinical studies. Several plant-based DPP-IV inhibitors, eg, Allium sativum, Morus Alba, Curcuma longa, Pterocarpus marsupium, and Taraxacum officinale, have established their functional role in inhibiting DPP-IV and have proven their effectiveness through studies in humans earning them a prominent place in therapeutic discovery.

The Current Place of DPP4 Inhibitors in the Evolving Landscape of Type 2 Diabetes Management: Is It Time to Bid Adieu?

During the last decade, the landscape of type 2 diabetes (T2D) management has been completely transformed, moving from a glucose-centric perspective to a holistic approach that also takes into account weight control and organ protection. Dipeptidyl peptidase-4 inhibitors (DPP4i) are oral agents that have been used for the treatment of T2D for almost 20 years. Although they present an excellent safety profile, including the risk of hypoglycemia, they lack the spectacular cardiorenal benefits and weight-loss effects of the newer antidiabetic agents. This poses the question of whether they still deserve a place in the arsenal of drugs against T2D. In this article, we use a hypothetical case scenario to illustrate possible patient profiles where DPP4i could prove useful in the clinical setting. We discuss the advantages and disadvantages of the category, focusing on glycemic control, weight management, and cardiorenal protection, which are the pillars of modern T2D management, also considering its safety profile and cost-effectiveness. We conclude that in most cases, DPP4i present a more favorable risk-benefit ratio compared to sulfonylureas, which are still widely prescribed throughout the world. We also suggest that future research should clarify the reasons behind the contradictory findings between human and animal studies on cardiorenal effects of the class and identify subgroups of patients who would derive most benefit with DPP4i treatment.

Dose decision of HSK7653 oral immediate release tablets in specific populations clinical trials based on mechanistic physiologically-based pharmacokinetic model

HSK7653, an oral dipeptidyl peptidase-4 inhibitor administered every 2 weeks, is a candidate for the treatment of type 2 diabetes mellitus. The major elimination pathway of HSK7653 in vivo is renal excretion, and hepatic metabolism and fecal excretion of unchanged compound contribute less to the systemic clearance of HSK7653. Considering the disposition characteristics and the potential indication population of HSK7653, evaluating the HSK7653 exposure in patients with renal impairment and geriatric populations is a prerequisite for bringing more benefits to the patients. Here, a PBPK model was developed based on in vitro experimental results, such as dissolution, permeability, and metabolism, and the in vivo renal clearance, to evaluate the effects of physiological factors and food on HSK7653 exposure in specific populations, including adult and elder individuals with renal impairment and geriatric populations. Simulation results showed that the AUC of HSK7653 increased by 46%, 82%, and 129% in adult patients with mild, moderate, and severe renal impairment, and by 56%, 78%, and 101% in patients aged 65-75, 75-85 and 85-95 years, respectively. The AUC increased in the range of 62%-83%, 98%-133%, and 153%-195% in elderly patients (65-95 years) with mild, moderate, and severe renal impairment, respectively. Moreover, two different absorption model development methods (dissolution profile method and the diffusion layer model method) predicted that food had no effect on the exposure of the same simulated population. Since the predicted AUC of HSK7653 at the 10 mg dose in various specific populations was still within the relatively flat results of the exposure-response analysis, the 10 mg dose of HSK7653 was first used to explore the exposure in the renal impairment population (CTR20221952).

Gut hormone-based pharmacology: novel formulations and future possibilities for metabolic disease therapy

Glucagon-like peptide-1 (GLP-1) receptor agonists are established pharmaceutical therapies for the treatment of type 2 diabetes and obesity. They mimic the action of GLP-1 to reduce glucose levels through stimulation of insulin secretion and inhibition of glucagon secretion. They also reduce body weight by inducing satiety through central actions. The GLP-1 receptor agonists used clinically are based on exendin-4 and native GLP-1 and are available as formulations for daily or weekly s.c. or oral administration. GLP-1 receptor agonism is also achieved by inhibitors of dipeptidyl peptidase-4 (DPP-4), which prevent the inactivation of GLP-1 and glucose-dependent insulinotropic polypeptide (GIP), thereby prolonging their raised levels after meal ingestion. Other developments in GLP-1 receptor agonism include the formation of small orally available agonists and compounds with the potential to pharmaceutically stimulate GLP-1 secretion from the gut. In addition, GLP-1/glucagon and GLP-1/GIP dual receptor agonists and GLP-1/GIP/glucagon triple receptor agonists have shown the potential to reduce blood glucose levels and body weight through their effects on islets and peripheral tissues, improving beta cell function and stimulating energy expenditure. This review summarises developments in gut hormone-based therapies and presents the future outlook for their use in type 2 diabetes and obesity.

Comparison of SGLT2 inhibitors with DPP-4 inhibitors combined with metformin in patients with acute myocardial infarction and diabetes mellitus

BACKGROUND

Although sodium-glucose cotransporter 2 inhibitors (SGLT2i) have demonstrated cardiovascular benefits in patients with type 2 diabetes mellitus, real-world evidence regarding their benefits to diabetic patients with acute myocardial infarction (AMI) is insufficient. This study evaluated cardiovascular outcomes by comparing SGLT2i with dipeptidyl peptidase-4 inhibitors (DPP-4i) in combination with metformin in diabetic patients with AMI.

METHODS

This study involved 779 diabetic participants with AMI from a Korean nationwide multicenter observational cohort, who were divided into two groups: (1) metformin plus SGLT2i group (SGLT2i group, n = 186) and (2) metformin plus DPP-4i (DPP-4i group, n = 593). The primary endpoint was one year of major adverse composite events (MACEs), a composite outcome of all-cause mortality, non-fatal myocardial infarction, any revascularization, cerebrovascular accident, and stent thrombosis. To balance the baseline differences, inverse probability of treatment weighting (IPTW) was performed.

RESULTS

After IPTW, the rate of MACEs in the SGLT2i group was not significantly lower than that in the DPP-4i group (hazard ratio [HR], 0.99; 95% confidence interval [Cl], 0.46 to 2.14, p = 0.983). In the unadjusted and adjusted analyses, all items for clinical outcomes were comparable between the two groups. In our exploratory analysis, the left ventricular ejection fraction showed a significant improvement in the SGLT2i group than in the DPP-4i group before achieving statistical balancing (6.10 ± 8.30 versus 2.95 ± 10.34, p = 0.007) and after IPTW adjustment (6.91 ± 8.91 versus 3.13 ± 10.41, p = 0.027).

CONCLUSIONS

Our findings demonstrated that SGLT2i did not influence the rate of MACEs compared with DPP-4i in combination with metformin in diabetic patients with AMI but did improve left ventricular ejection fraction.

TRIAL REGISTRATION

Not applicable (retrospectively registered).

Incident and recurrent hypoglycaemia with linagliptin and glimepiride over a median of 6 years in the CAROLINA cardiovascular outcome trial

AIM

The CAROLINA trial established non-inferiority of linagliptin versus glimepiride for major adverse cardiovascular events in patients with relatively early type 2 diabetes at increased cardiovascular risk. In pre-specified and post-hoc analyses, we investigated treatment effects on total hypoglycaemic burden in CAROLINA.

MATERIALS AND METHODS

Patients were randomized and treated with 5 mg linagliptin (n = 3014) or 1-4 mg glimepiride (n = 3000) once daily added to standard care. Hypoglycaemia captured from investigator-reported adverse events was analysed with Poisson and negative binomial regressions for the first and total (first plus recurrent) events, respectively. The influence of insulin initiation and glycated haemoglobin (HbA1c) change on the treatment effect for hypoglycaemia was also explored.

RESULTS

Over 6.3 years median follow-up, average HbA1c over time did not differ between linagliptin versus glimepiride (weighted mean difference [95% confidence interval]: 0.00%, [-0.05, 0.05]), nor did insulin initiation (18.6% vs. 19.2% of patients, respectively), whereas body weight was lower with linagliptin (-1.54 kg, [-1.80, -1.28]). Hypoglycaemia frequency was lower with linagliptin across all hypoglycaemia categories, including severe episodes. Rate ratios (95% confidence interval) for first and total events for investigator-reported hypoglycaemia were 0.21 (0.19-0.24) and 0.12 (0.10-0.14), respectively, with 8.7 first and 60.8 total estimated events prevented/100 patient-years with linagliptin versus glimepiride. These differences occurred during night-time and daytime, and in subgroup analyses of total events. Treatment differences in hypoglycaemia were neither impacted by HbA1c changes nor insulin initiation.

CONCLUSIONS

Across the severity spectrum, linagliptin substantially reduced the hypoglycaemic burden versus glimepiride in patients with relatively early type 2 diabetes at increased cardiovascular risk.

Effect of dipeptidyl peptidase-4 inhibitors on postprandial glucagon level in patients with type 2 diabetes mellitus: A systemic review and meta-analysis

AIMS

Hyperglucagonemia occurs in the pathogenesis of type 2 diabetes mellitus (T2DM). In this meta-analysis, we summarized the effects of DPP4 inhibitors on glucagon levels in patients with T2DM.

MATERIALS AND METHODS

Randomized controlled trials (RCTs) comparing the influence of DPP4 inhibitors on circulating glucagon levels with placebo or other oral antidiabetic drugs (OADs) in patients with T2DM were identified by searches of Medline (PubMed), Embase (Ovid), and CENTER (Cochrane Library). Only studies reporting changes in glucagon level presented as total area under the curve (AUC_glucagon) using a meal or oral glucose tolerance test were included. Results were combined using a random-effects model that incorporated potential heterogeneity among the included studies.

RESULTS

A total of 36 RCTs with moderate to high quality were included. Overall, the numbers of T2DM patients included for the meta-analyses comparing DPP4 inhibitors with placebo and other OADs were 4266 and 1652, respectively. Compared to placebo, DPP4 inhibitors significantly reduced circulating glucagon levels (standard mean difference [SMD]: -0.32, 95% CI: -0.40 to -0.24, P<0.001; I^{2 =} 28%). Analysis of subgroups revealed that study characteristics had no significant effect on results, such as study design (parallel group or crossover), number of patients, mean patient age, proportion of men, baseline HbA1c, duration of diabetes, background therapy, treatment duration, or methods for glucagon measurement (all P for subgroup differences >0.05). Moreover, DPP4 inhibitors significantly reduced glucagon levels compared to other OADs (SMD: -0.35, 95% CI: -0.53 to -0.16, P<0.001; I² = 66%), and the reduction in glucagon was greater in comparison with insulin secretagogues than in comparison with non-insulin secretagogues (P for subgroup difference =0.03).

SYSTEMATIC REVIEW REGISTRATION

https://inplasy.com/, identifier INPLASY202280104.

CONCLUSIONS

DPP4 inhibitors are effective at reducing the circulating postprandial glucagon level in T2DM patients.

Small dense low-density lipoprotein-lowering agents

Metabolic disorders, including obesity, diabetes, and hyperlipidemia, as well as cardiovascular diseases (CVD), particularly atherosclerosis, are still leading causes of death worldwide. Plasma levels of low-density lipoprotein (LDL) are currently being considered as a critical risk factor for the diseases mentioned above, especially atherosclerosis. Because of the heterogeneous nature of LDL, many studies have already been conducted on its subclasses, especially small dense LDL (sdLDL). According to available evidence, sdLDL levels can be considered as an ideal alternative to LDL levels for monitoring CVD and early diagnosis of atherosclerosis. Recently, several researchers have focused on factors that are able to decrease sdLDL levels and improve health quality. Therefore, the purpose of this study is to describe the production process of sdLDL particles and review the effects of pharmaceutical and dietary agents as well as lifestyle on sdLDL plasma levels. In brief, their mechanisms of action are discussed. Apparently, cholesterol and LDL-lowering compounds are also effective in the reduction of sdLDL levels. In addition, improving lipid profile, especially the reduction of triglyceride levels, appropriate regimen, and lifestyle can decrease sdLDL levels. Therefore, all the aforementioned parameters should be taken into consideration simultaneously in sdLDL levels reducing strategies.

A Comprehensive Review and Perspective on Natural Sources as Dipeptidyl Peptidase-4 Inhibitors for Management of Diabetes

Type 2 diabetes mellitus (T2DM) is an increasing global public health problem, and its prevalence is expected to rise in coming decades. Dipeptidyl peptidase-4 (DPP-4) is a therapeutic target for the management of T2DM, and its inhibitors prevent the degradation of glucose-dependent insulinotropic peptide and glucagon-like peptide 1, and thus, maintain their endogenous levels and lower blood glucose levels. Various medicinal plant extracts and isolated bioactive compounds exhibit DPP-4 inhibitory activity. In this review, we discussed different natural sources that have been shown to have anti-diabetic efficacy with a particular emphasis on DPP-4 inhibition. Furthermore, the effect of DPP-4 inhibition on pancreatic beta cell function, skeletal muscle function, and the glucose-lowering mechanisms were also discussed. We believe that scientists looking for novel compounds with therapeutic promise against T2DM will be able to develop antidiabetic drugs using these natural sources.

Glucose-lowering action through targeting islet dysfunction in type 2 diabetes: Focus on dipeptidyl peptidase-4 inhibition

Dipeptidyl peptidase-4 (DPP-4) inhibition is a glucose-lowering medication for type 2 diabetes. It works through stimulation of insulin secretion and inhibition of glucagon secretion in a glucose-dependent manner, resulting in lowered fasting and postprandial glycemia with low risk of hypoglycemia. As impaired insulin secretion and augmented glucagon secretion are key factors underlying hyperglycemia in type 2 diabetes, DPP-4 inhibition represents a therapy that targets the underlying mechanisms of the disease. If insufficient in monotherapy, it can preferably be used in combination with metformin, which targets insulin resistance, and also in combination with sodium-glucose cotransporter 2 inhibition, thiazolidinediones and insulin, which target other mechanisms. In individuals of East Asian origin, islet dysfunction is of particular importance for the development of type 2 diabetes. Consequently, it has been shown in several studies that DPP-4 is efficient in these populations. This mini-review highlights the islet mechanisms of DPP-4 inhibition, islet dysfunction as a key factor for hyperglycemia in type 2 diabetes and that, consequently, DPP-4 is of particular value in populations where islet dysfunction is central, such as in individuals of East Asian origin.

Antioxidative Potentials of Incretin-Based Medications: A Review of Molecular Mechanisms

Glucagon-like peptide 1 receptor agonists and dipeptidyl-peptidase 4 inhibitors are medications used for managing diabetes, mimicking the metabolic effects of incretin hormones. Recent evidence suggests that these medications have antioxidative potentials in the diabetic milieu. The pathophysiology of most diabetic complications involves oxidative stress. Therefore, if incretin-based antidiabetic medications can alleviate the free radicals involved in oxidative stress, they can potentially provide further therapeutic effects against diabetic complications. However, the molecular mechanisms by which these medications protect against oxidative stress are not fully understood. In the current review, we discuss the potential molecular mechanisms behind these pharmacologic agents' antioxidative properties.

Effect of linagliptin on glucose metabolism and pancreatic beta cell function in patients with persistent prediabetes after metformin and lifestyle

The goal of the study was to evaluate the effect of adding linagliptin to metformin and lifestyle on glucose levels and pancreatic β-cell function in patients with persistent impaired glucose tolerance (IGT) after 12 months of metformin and lifestyle. A single center parallel double-blind randomized clinical trial with 6 months of follow-up was performed in patients with persistent IGT after 12 months of treatment with metformin and lifestyle; patients were randomized to continue with metformin 850 mg twice daily (M group, n = 12) or linagliptin/metformin 2.5/850 mg twice daily (LM group, n = 19). Anthropometric measurements were obtained by standard methods and by bioelectrical impedance; glucose was measured by dry chemistry, insulin by chemiluminescence, and pancreatic β-cell function was calculated with the disposition index using glucose and insulin values during oral glucose tolerance test (OGTT) and adjusting by insulin sensitivity. The main outcomes were glucose levels during OGTT and pancreatic β-cell function. Patients in the LM group had a reduction in weight (-1.7 ± 0.6, p < 0.05) and body mass index (BMI, -0.67 ± 0.2, p < 0.05). Glucose levels significantly improved in LM group with a greater reduction in the area under the glucose curve during OGTT (AUCGluc_{0_120min}) as compared to the M group (-4425 ± 871 vs -1116 ± 1104 mg/dl/120 min, p < 0.001). Pancreatic β-cell function measured with the disposition index, improved only in LM group (2.3 ± 0.23 vs 1.7 ± 0.27, p 0.001); these improvements persisted after controlling for OGTT glucose levels. The differences in pancreatic β-cell function persisted also after pairing groups for basal AUCGluc_{0_120min}. The addition of linagliptin to patients with persistent IGT after 12 months of treatment with metformin and lifestyle, improved glucose levels during OGTT and pancreatic β-cell function after 6 months of treatment.Trial registration: Clinicaltrials.gov with the ID number NCT04088461.

Hypoglycemia Associated With Drug-Drug Interactions in Patients With Type 2 Diabetes Mellitus Using Dipeptidylpeptidase-4 Inhibitors

Background: Dipeptidylpeptidase-4 inhibitors (DPP-4i′s) are considered to be safe for patients with type 2 diabetes mellitus (T2DM). However, little is known about drug–drug interactions between DPP-4i′s and concurrent medications.

Methods: Data on patients using DPP-4i′s for T2DM during 2011–2017 were retrieved from Chang Gung Research database provided by Chang Gung Memorial Hospital. Patients were excluded if they were aged <30 years or >90 years; had incomplete demographic data; had insulinoma; or had records of concomitant insulin use. A generalized estimating equation–based Poisson model was employed for statistical analysis. The primary outcome was hypoglycemia events.

Results: We retrieved data on a total of 97,227 patients using DPP-4i′s. After patients were excluded according to the mentioned criteria, the remaining 77,047 DPP-4i users were studied (mean age 64 ± 12 years, men 54.4%). The most common medications coprescribed with DPP4is over all person-quarters were acetaminophen, simvastatin, fluvastatin, and colchicine (all >20,000 person-quarters). The combinations of a DPP-4i with bumetanide, captopril, colchicine, acetaminophen, cotrimoxazole, and pantoprazole were associated with an increased risk of hypoglycemia. Compared with the ratios observed for person-quarters of DPP-4i use alone (reference category), the adjusted prevalence ratios per 100 person-years of hypoglycemia for person-quarters of DPP-4i use in combination with bumetanide, captopril, colchicine, acetaminophen, cotrimoxazole, and pantoprazole were 2.44 (95% confidence interval [CI], 1.78–3.36), 2.97 (95% CI, 2.26–3.90), 1.87 (95% CI, 1.44–2.42), 2.83 (95% CI, 2.44–3.29), 2.27 (95% CI, 1.27–4.04), and 3.03 (95% CI, 1.96–4.68), respectively.

Conclusion: Among patients taking DPP-4i′s for T2DM, concurrent use of such inhibitors with bumetanide, captopril, acetaminophen, and pantoprazole was associated with an increased risk of hypoglycemia compared with the use of DPP-4i′s alone. Physicians prescribing DPP-4i′s should consider the potential risks associated with their concomitant use with other drugs.

Effect of Teneligliptin versus Sulfonylurea on Major Adverse Cardiovascular Outcomes in People with Type 2 Diabetes Mellitus: A Real-World Study in Korea

BACKGROUND

Results regarding the cardiovascular (CV) effects of dipeptidyl peptidase-4 (DPP-4) inhibitors are inconsistent. This study aimed to assess the effects of teneligliptin, a DPP-4 inhibitor, on the risk of major CV outcomes in type 2 diabetes mellitus (T2DM) patients compared to sulfonylurea.

METHODS

From January 1, 2015 to December 31, 2017, we conducted a retrospective cohort study using the Korean National Health Insurance Service database. A total of 6,682 T2DM patients who were newly prescribed DPP-4 inhibitors or sulfonylurea were selected and matched in a 1:1 ratio by propensity score. The hazard ratios (HRs) for all-cause mortality, hospitalization for heart failure (HHF), all-cause mortality or HHF, myocardial infarction (MI), stroke, and hypoglycemia were assessed.

RESULTS

During 641 days of follow-up, the use of teneligliptin was not associated with an increased risk of all-cause mortality (HR, 1.00; 95% confidence interval [CI], 0.85 to 1.19), HHF (HR, 0.99; 95% CI, 0.86 to 1.14), all-cause mortality or HHF (HR, 1.02; 95% CI, 0.90 to 1.14), MI (HR, 0.90; 95% CI, 0.68 to 1.20), and stroke (HR, 1.00; 95% CI, 0.86 to 1.17) compared to the use of sulfonylurea. However, it was associated with a significantly lower risk of hypoglycemia (HR, 0.68; 95% CI, 0.49 to 0.94) compared to sulfonylurea therapy.

CONCLUSION

Among T2DM patients, teneligliptin therapy was not associated with an increased risk of CV events including HHF, but was associated with a lower risk of hypoglycemia compared to sulfonylurea therapy.

MiR-34a-5p and miR-452-5p: The Novel Regulators of Pancreatic Endocrine Dysfunction in Diabetic Zucker Rats?

Objective: The pancreatic endocrinal system dominates the regulation of blood glucose levels in vivo, and the dysfunction of pancreatic endocrine β-cells is a major cause of the occurrence and development of Type 2 diabetes (T2D). Although microRNA (miRNA) have been found to be key regulators of pancreatic β-cells proliferation, differentiation and apoptosis, the underlying mechanism remains enigmatic. The aim of this study was to identify several novel miRNAs which might be involved in the etiopathogenesis of diabetic β-cells dysfunction. Methods: The miRNA expression profiles in the pancreas of high-fat diet (HFD) fed Zucker diabetic fatty (ZDF) rats and Zucker lean (ZL) rats feed with normal-fat diet (NFD) were detected by using miRNA microarray chip, and individually verified the most significant factors by quantitative real-time polymerase chain reaction (qRT-PCR) assay. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were used to predict the target genes related to each of the identified miRNAs and the functions of these target genes in different metabolic signaling pathways. Results: Compared with the ZL rats, a total of 24 differentially expressed miRNAs were detected in ZDF rats. Among which miR-34a-5p and miR-452-5p were the most significantly up-regulated and down-regulated respectively. These miRNAs have not been reported in rats' pancreas before. By GO and KEGG enrichment analyses, we found that miR-34a-5p could negatively regulate pancreatic β-cell proliferation through the involvement of Wnt signaling pathway. In addition, it was also found to regulate insulin secretion through the insulin signaling pathway to modulate blood glucose levels. At the same time, miR-452-5p was found to positively regulate the activity of the key rate-limiting enzyme branched-chain α-keto acid dehydrogenase-β (BCKDHB) in the catabolism of branched chain amino acids (BCAA), leading to mitochondrial dysfunction in pancreatic β-cells. Conclusions: miR-34a-5p and miR-452-5p were identified as the novel regulators of pancreatic endocrine dysfunction. These miRNAs might have the potential to be utilized as the new predictive biomarkers for the diagnosis of the occurrence and development of T2D, as well as the therapeutic targets for T2D treatment.

The effects of ertugliflozin on β-cell function: Pooled analysis from four phase 3 randomized controlled studies

AIM

To identify potential predictors and mediators of changes in β-cell function in response to ertugliflozin treatment in people with type 2 diabetes mellitus (T2DM).

PARTICIPANTS AND METHODS

Data from patients with T2DM randomized to ertugliflozin (5 or 15 mg; observations from both doses were pooled) or placebo in four phase 3 clinical studies (clinicaltrials.gov: NCT01958671, NCT02226003, NCT02036515, NCT02099110) were pooled and analysed. Change from baseline in β-cell function at week 26 was assessed, and its potential predictors and mediators were analysed using linear and multiple regression analyses.

RESULTS

Compared with placebo, ertugliflozin improved β-cell function when assessed by mean percent change from baseline in homeostatic model assessment of β-cell function (HOMA-%β; ertugliflozin: 14.7%, 95% confidence interval [CI] 12.3, 17.1; placebo: -0.4%, 95% CI -3.4, 2.5], but not when assessed by change in C-peptide index following a mixed meal tolerance test. Change in HOMA-%β correlated with change from baseline in glycated haemoglobin (HbA1c) and treatment with ertugliflozin, and weakly with change from baseline in body weight. In the ertugliflozin group, change in HOMA-%β correlated with baseline fasting plasma glucose (FPG; r = 0.235, P < 0.001), baseline HbA1c (r = 0.138, P < 0.001), baseline homeostatic model assessment of insulin resistance (HOMA-IR; r = 0.162, P < 0.01), and baseline HOMA-%β (r = -0.321, P < 0.001) in linear regression analyses. Multiple regression analyses yielded similar results.

DISCUSSION

In people with T2DM, ertugliflozin treatment improved fasting β-cell function, but no effect on postprandial β-cell function was observed in this analysis. Improvement in HOMA-%β was predicted by high baseline FPG, HbA1c, HOMA-IR, and low baseline HOMA-%β, and mediated by ertugliflozin treatment, and improved HbA1c and body weight.

β-cell replenishment: Possible curative approaches for diabetes mellitus

AIMS

Diabetes mellitus (DM) is a disorder of heterogeneous etiology marked by persistent hyperglycemia. Exogenous insulin is the only treatment for type 1 diabetes (T1D). Islet transplantation is a potential long cure for T1D but is disapproved due to the possibility of immune rejection in the later stage. The approaches used for treating type 2 diabetes (T2D) include diet restrictions, weight management and pharmacological interventions. These procedures have not been able to boost the quality of life for diabetic patients owing to the complexity of the disorder.

DATA SYNTHESIS

Hence, research has embarked on permanent ways of managing, or even curing the disease. One of the possible approaches to restore the pancreas with new glucose-responsive β-cells is by their regeneration. Regeneration of β-cells include islet neogenesis, dedifferentiation, and trans-differentiation of the already differentiated cells.

CONCLUSIONS

This review briefly describes the islet development, functions of β-cells, mechanism and factors involved in β-cell death. It further elaborates on the potential of the existing and possible therapeutic modalities involved in the in-vivo replenishment of β-cells with a focus on exercise, diet, hormones, small molecules, and phytochemicals.

Persistent whole day meal effects of three dipeptidyl peptidase-4 inhibitors on glycaemia and hormonal responses in metformin-treated type 2 diabetes

AIM

Dipeptidyl peptidase-4 (DPP-4) inhibition has effects on both fasting and postprandial glucose. However, the extent of this effect over the whole day and whether different DPP-4 inhibitors have the same effects have not been established. We therefore explored the whole day effects of three different DPP-4 inhibitors versus placebo on glucose, islet and incretin hormones after ingestion of breakfast, lunch and dinner in subjects with metformin-treated and well-controlled type 2 diabetes.

METHODS

The study was single-centre and crossover designed, involving 24 subjects [12 men, 12 women, mean age 63 years, body mass index 31.0 kg/m² , glycated haemoglobin 44.7 mmol/mol (6.2%)], who underwent four test days in random order. Each whole day test included ingestion of standardized breakfast (525 kcal), lunch (780 kcal) and dinner (560 kcal) after intake of sitagliptin (100 mg) or vildagliptin (50 mg twice), or saxagliptin (5 mg) or placebo.

RESULTS

Compared with placebo, DPP-4 inhibition reduced glucose levels, increased beta-cell function (insulin secretory rate in relation to glucose), suppressed glucagon, increased intact glucagon-like-peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) but suppressed total GLP-1 and GIP after all three meals. The effects were sustained throughout the daytime period with similar changes after each meal and did not differ between the DPP-4 inhibitors.

CONCLUSIONS

DPP-4 inhibition has persistent daytime effects on glucose, islet and incretin hormones with no difference between three different DPP-4 inhibitors.

Effect of Dipeptidyl-Peptidase 4 Inhibitors on Circulating Oxidative Stress Biomarkers in Patients with Type 2 Diabetes Mellitus

Pre-clinical studies suggested potential cardiovascular benefits of dipeptidyl peptidase-4 inhibitors (DPP4i), however, clinical trials showed neither beneficial nor detrimental effects in patients with type 2 diabetes mellitus (T2DM). We examined the effects of DPP4i on several circulating oxidative stress markers in a cohort of 32 T2DM patients (21 males and 11 post-menopausal females), who were already on routine antidiabetic treatment. Propensity score matching was used to adjust demographic and clinical characteristics between patients who received and who did not receive DPP4i. Whole-blood reactive oxygen species (ROS), plasma advanced glycation end products (AGEs), advanced oxidation protein products (AOPP), carbonyl residues, as well as ferric reducing ability of plasma (FRAP) and leukocyte DNA oxidative damage (Fpg sites), were evaluated. With the exception of Fpg sites, that showed a borderline increase in DPP4i users compared to non-users (p = 0.0507), none of the biomarkers measured was affected by DPP4i treatment. An inverse correlation between estimated glomerular filtration rate and AGEs (p < 0.0001) and Fpg sites (p < 0.05) was also observed. This study does not show any major effect of DPP4i on oxidative stress, assessed by several circulating biomarkers of oxidative damage, in propensity score-matched cohorts of T2DM patients.

The Incretin Effect in Female Mice With Double Deletion of GLP-1 and GIP Receptors

To establish the contribution of glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) for the incretin effect after oral glucose, studies were undertaken in female mice with genetic deletion of receptors for GIP and GLP-1 (double incretin receptor knockout [DIRKO] mice) and their wild-type (WT) counterparts. Insulin secretion was explored after oral glucose (doses ranging from 0 to 100 mg), after intravenous glucose (doses ranging from 0 to 0.75 g/kg), and after oral and intravenous glucose at matching circulating glucose. DIRKO mice had glucose intolerance after oral glucose challenges in association with impaired beta-cell function. Suprabasal area under the curve for C-peptide (AUC_C-peptide) correlated linearly with suprabasal AUC_glucose both in WT (r = 0.942, P = .017) and DIRKO mice (r = 0.972, P = .006). The slope of this regression was lower in DIRKO than in WT mice (0.012 ± 0.006 vs 0.031 ± 0.006 nmol C-peptide/mmol glucose, P = .042). In contrast, there was no difference in the insulin response to intravenous glucose between WT and DIRKO mice. Furthermore, oral and intravenous glucose administration at matching glucose levels showed that the augmentation of insulin secretion after oral glucose (the incretin effect) in WT mice (11.8 ± 2.3 nmol/L min) was entirely absent in DIRKO mice (3.3 ± 1.2 nmol/L min). We conclude that GIP and GLP-1 are required for normal glucose tolerance and beta-cell function after oral glucose in mice, that they are the sole incretin hormones after oral glucose at higher dose levels, and that they contribute by 65% to insulin secretion after oral glucose.

Comparison of the Effectiveness and Safety of Vildagliptin Add-On to Metformin Versus Other Oral Dual Antidiabetes Agents in Patients with Type 2 Diabetes: The China Prospective Diabetes Study

INTRODUCTION

The efficacy and safety of vildagliptin alone or with metformin is well established by randomized trials, but it is unknown whether it can be extrapolated to the real-world setting in Chinese patients with type 2 diabetes mellitus (T2DM). This study aimed to assess the effectiveness and safety of vildagliptin add-on to metformin versus dual oral antidiabetes drug (OAD), non-vildagliptin combination therapies in real-world Chinese patients with T2DM.

METHODS

The China Prospective Diabetes Study was a post-marketing, prospective, multicenter, observational, real-world study conducted in 52 centers. Patients inadequately controlled with OAD monotherapy and who initiated vildagliptin add-on to metformin (VM cohort) or two OADs other than vildagliptin (comparator cohort) were included for the present analysis. The composite primary endpoint was glycated hemoglobin (HbA1c) <  7% and without tolerability events (hypoglycemia, weight gain ≥ 3%, or discontinuation due to gastrointestinal events) at 12 months. Secondary endpoints included change in HbA1c from baseline, subgroup analysis, and tolerability. Propensity score matching analysis was performed to adjust for baseline covariates imbalance (body mass index (BMI) and HbA1c).

RESULTS

A total of 604 patients received VM and 670 received comparator therapy. Patients who received VM were younger, more obese, and had a higher baseline HbA1c and a shorter duration of T2DM. After propensity score matching, there were 530 patients per cohort. After 12-month treatment, the success rates of the composite primary endpoint were 50.9% and 33.0% in the VM and comparator cohorts, respectively (P < 0.001; odds ratio = 2.10, 95% confidence interval (CI) 1.64-2.70). Furthermore, the success rates of the composite endpoint were higher with VM across geographic area, BMI, and baseline HbA1c subgroups. Fewer tolerability events occurred in the VM cohort versus the comparator cohort (8.3% vs. 16.2%, P < 0.001; relative risk = 0.51, 95% CI 0.36-0.72).

CONCLUSION

Compared with dual OAD non-vildagliptin combination therapies, vildagliptin add-on to metformin is effective and safe to achieve glycemic control in Chinese patients with T2DM.

FUNDING

Novartis.

Relationship between diet/exercise and pharmacotherapy to enhance the GLP-1 levels in type 2 diabetes

The rapid rise in the prevalence of type 2 diabetes mellitus (T2DM) poses a huge healthcare burden across the world. Although there are several antihyperglycaemic agents (AHAs) available including addition of new drug classes to the treatment algorithm, more than 50% of patients with T2DM do not achieve glycaemic targets, suggesting an urgent need for treatment strategies focusing on prevention and progression of T2DM and its long-term complications. Lifestyle changes including implementation of healthy diet and physical activity are cornerstones for the management of T2DM. The positive effects of diet and exercise on incretin hormones such as glucagon-like peptide-1 (GLP-1) have been reported. We hypothesize an IDEP concept (Interaction between Diet/Exercise and Pharmacotherapy) aimed at modifying the diet and lifestyle, along with pharmacotherapy to enhance the GLP-1 levels, would result in good glycaemic control in patients with T2DM. Consuming protein-rich food, avoiding saturated fatty acids and making small changes in eating habits such as eating slowly with longer mastication time can have a positive impact on the GLP-1 secretion and insulin levels. Further the type of physical activity (aerobic/resistance training), intensity of exercise, duration, time and frequency of exercise have shown to improve GLP-1 levels. Apart from AHAs, a few antihypertensive drugs and lipid-lowering drugs have also shown to increase endogenous GLP-1 levels, however, due to quick degradation of GLP-1 by dipeptidyl peptidase-4 (DPP-4) enzyme, treatment with DPP-4 inhibitors would protect GLP-1 from degradation and prolong its activity. Thus, IDEP concept can be a promising treatment strategy, which positively influences the GLP-1 levels and provide additive benefits in terms of improving metabolic parameters in patients with T2DM and slowing the progression of T2DM and its associated complications.

A Novel Dipeptidyl Peptidase IV Inhibitory Tea Peptide Improves Pancreatic β-Cell Function and Reduces α-Cell Proliferation in Streptozotocin-Induced Diabetic Mice

Dipeptidyl peptidase IV (DPP-IV) inhibitors occupy a growing place in the drugs used for the management of type 2 diabetes. Recently, food components, including food-derived bioactive peptides, have been suggested as sources of DPP-IV inhibitors without side effects. Chinese black tea is a traditional health beverage, and it was used for finding DPP-IV inhibitory peptides in this study. The ultra-filtrated fractions isolated from the aqueous extracts of black tea revealed DPP-IV inhibitory activity in vitro. Four peptides under 1 kDa were identified by SDS-PAGE and LC-MS/MS (Liquid Chromatography-Mass Spectrometry-Mass Spectrometry) from the ultra-filtrate. The peptide II (sequence: AGFAGDDAPR), with a molecular mass of 976 Da, showed the greatest DPP-IV inhibitory activity (in vitro) among the four peptides. After administration of peptide II (400 mg/day) for 57 days to streptozotocin (STZ)-induced hyperglycemic mice, the concentration of glucagon-like peptide-1 (GLP-1) in the blood increased from 9.85 ± 1.96 pmol/L to 19.22 ± 6.79 pmol/L, and the insulin level was increased 4.3-fold compared to that in STZ control mice. Immunohistochemistry revealed the improved function of pancreatic beta-cells and suppressed proliferation of pancreatic alpha-cells. This study provides new insight into the use of black tea as a potential resource of food-derived DPP-IV inhibitory peptides for the management of type 2 diabetes.

Identification of novel uracil derivatives incorporating benzoic acid moieties as highly potent Dipeptidyl Peptidase-IV inhibitors

Dipeptidyl Peptidase-IV (DPP-4) is a validated therapeutic target for type 2 diabetes. Aiming to interact with both residues Try629 and Lys554 in S₂' site, a series of novel uracil derivatives 1a-l and 2a-i incorporating benzoic acid moieties at the N₃ position were designed and evaluated for their DPP-4 inhibitory activity. Structure-activity relationships (SAR) study led to the identification of the optimal compound 2b as a potent and selective DPP-4 inhibitor (IC₅₀ = 1.7 nM). Docking study revealed the additional salt bridge formed between the carboxylic acid and primary amine of Lys554 has a key role in the enhancement of the activity. Furthermore, compound 2b exhibited no cytotoxicity in human hepatocyte LO2 cells up to 50 μM. Subsequent in vivo evaluations revealed that the ester of 2b robustly improves the glucose tolerance in normal mice. The overall results have shown that compound 2b has the potential to a safe and efficacious treatment for T2DM.

Ketosis-Prone Type 2 Diabetes: A Case Series

Ketosis-prone type 2 diabetes ("Flatbush diabetes") carries features of both classical type 1 and type 2 diabetes and is highly prevalent in African populations. The disease, which is highly ketosis-prone, but neither chronically insulinopenic nor autoimmune, is discussed regarding pathogenesis, diagnosis and treatment from a patient case perspective.

DPP-4 Inhibition and the Path to Clinical Proof

In the 1990s it was discovered that the enzyme dipeptidyl peptidase-4 (DPP-4) inactivates the incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). DPP-4 inhibition results in raised levels of the two incretin hormones which in turn result in lowering of circulating glucose through stimulation of insulin secretion and inhibition of glucagon secretion. Since then, several small orally available molecules have been developed with DPP-4 inhibitory action. Early studies in the 1990s showed that the DPP-4 inhibitors improve glycemia in animals. Subsequent clinical studies during the 2000s showed a glucose-lowering action of DPP-4 inhibitors also in human subjects with type 2 diabetes. This action was seen when DPP-4 inhibitors were used both as monotherapy and as add-on to other therapies, i.e., metformin, sulfonylureas, tiazolidinediones or exogenous insulin. The DPP-4 inhibitors were also found to have a low risk of adverse events, including hypoglycemia. Five of the DPP-4 inhibitors (sitagliptin, vildagliptin, alogliptin, saxagliptin and linagliptin) were approved by regulatory authorities and entered the market between 2006 and 2013. DPP-4 inhibitors have thereafter undergone long-term cardiovascular outcome trials, showing non-inferiority for risk of major acute cardiovascular endpoints. Also the risk of other potential adverse events is low in these long-term studies. DPP-4 inhibitors are at present included in guidelines as a glucose-lowering concept both as monotherapy and in combination therapies. This article summarizes the development of the DPP-4 inhibition concept from its early stages in the 1990s. The article underscores that the development has its basis in scientific studies on pathophysiology of type 2 diabetes and the importance of targeting the islet dysfunction, that the development has been made possible through academic science in collaboration with the research-oriented pharmaceutical industry, and that the development of a novel concept takes time and requires focused efforts, persistence and long-term perserverance.

Insights Into GLP-1 and GIP Actions Emerging From Vildagliptin Mechanism Studies in Man

Vildagliptin blocks glucagon like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) inactivation of the meal induced increases in GLP-1 and GIP so that elevated GLP-1 and GIP levels are maintained over 24 h. The primary insulin secretion effect of vildagliptin is to improve the impaired sensitivity of the β-cells to glucose in subjects with impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) and in patients with type 2 diabetes mellitus (T2DM); this effect was seen acutely and maintained over at least 2 years in patients with T2DM. Vildagliptin was also associated with improved β-cell function that is likely secondary to the improved metabolic state. Although there was no evidence of restoration of β-cell mass, the preponderance of the vildagliptin data does indicate that for at least 2 years β-cell function was maintained in vildagliptin treated patients but not in the untreated patients. Vildagliptin suppressed an inappropriate glucagon response to an oral glucose challenge in patients with T2DM, to a mixed meal challenge in patients with T2DM and type 1 diabetes mellitus, and to a mixed meal challenge in subjects with IGT and IFG. The improved glucagon response was maintained for at least 2 years in patients with T2DM and there was no change in the glucagon response in normoglycemic individuals. Vildagliptin lowered glucose levels into the normal range without increasing hypoglycemia. These hypoglycemic benefits appear to be secondary in large part to the improved sensitivity of both the β and α-cell to glucose. In the case of the α-cell, if glucose levels are high, GLP-1 attenuates the glucagon levels and if glucose levels are low, GIP increases glucagon levels. Vildagliptin reduces fatty acid flux from the adipocyte leading to reduced liver fat which in turn leads to increased glucose utilization. The reduced glycosuria and reduced lipo-toxicity associated with vildagliptin therapy does not lead to weight gain presumably due to increased fat mobilization and oxidation during meals and to reduced fat extraction from the gut.

Fibroblast activation protein is dispensable for control of glucose homeostasis and body weight in mice

Objective

Fibroblast Activation Protein (FAP), an enzyme structurally related to dipeptidyl peptidase-4 (DPP-4), has garnered interest as a potential metabolic drug target due to its ability to cleave and inactivate FGF-21 as well as other peptide substrates. Here we investigated the metabolic importance of FAP for control of body weight and glucose homeostasis in regular chow-fed and high fat diet-fed mice.

Methods

FAP enzyme activity was transiently attenuated using a highly-specific inhibitor CPD60 and permanently ablated by genetic inactivation of the mouse Fap gene. We also assessed the FAP-dependence of CPD60 and talabostat (Val-boroPro), a chemical inhibitor reportedly targeting both FAP and dipeptidyl peptidase-4

Results

CPD60 robustly inhibited plasma FAP activity with no effect on DPP-4 activity. Fap gene disruption was confirmed by assessment of genomic DNA, and loss of FAP enzyme activity in plasma and tissues. CPD60 did not improve lipid tolerance but modestly improved acute oral and intraperitoneal glucose tolerance in a FAP-dependent manner. Genetic inactivation of Fap did not improve glucose or lipid tolerance nor confer resistance to weight gain in male or female Fap^−/− mice fed regular chow or high-fat diets. Moreover, talabostat markedly improved glucose homeostasis in a FAP- and FGF-21-independent, DPP-4 dependent manner.

Conclusion

Although pharmacological FAP inhibition improves glucose tolerance, the absence of a metabolic phenotype in Fap^−/−mice suggest that endogenous FAP is dispensable for the regulation of murine glucose homeostasis and body weight. These findings highlight the importance of characterizing the specificity and actions of FAP inhibitors in different species and raise important questions about the feasibility of mouse models for targeting FAP as a treatment for diabetes and related metabolic disorders.

•

Acute inhibition of FAP enzyme activity improves glucose tolerance in mice.

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Fap knockout mice exhibit normal glucose and lipid tolerance.

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Fap knockout mice do not resist obesity after high fat feeding.

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Talabostat robustly lowers glucose in a FAP and FGF21-independent manner.

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Talabostat, but not CPD60, requires DPP4 to exert its full metabolic activity.

Comparison of dipeptidyl peptidase-4 inhibitors and pioglitazone combination therapy versus pioglitazone monotherapy in type 2 diabetes: A system review and meta-analysis

BACKGROUND

Dipeptidyl peptidase-4 (DPP-4) inhibitor and pioglitazone combination therapy have been widely used for patients with inadequate glycemic control on monotherapy. This meta-analysis assessed the efficacy and safety of this combination therapy in patients with type 2 diabetes mellitus (T2DM).

METHODS

We searched the MEDLINE, Embase, and Cochrane databases. Studies were eligible if they were randomized controlled trials (RCTs) on DPP-4 inhibitor and pioglitazone combination therapy in patients with T2DM through the end of February 2016, using the keywords "alogliptin," "dutogliptin, " "linagliptin," "saxagliptin," "sitagliptin," "vildagliptin," "gliptins," "DPP-4 inhibitor," and "pioglitazone." RCTs were selected if they compared DPP-4 inhibitors and pioglitazone as combination therapy; treatment duration was ≥12 weeks; and the reported data included hemoglobin A1c (HbA1c) or fasting plasma glucose (FPG) change, total or any other system Adverse Events (AEs). We estimated effect size with random-effects or fixed-effects meta-analysis, I statistic was used to estimate heterogeneity of results.

RESULTS

Seven RCTs were included. Compared with pioglitazone monotherapy, combination DPP-4 inhibitor and pioglitazone therapy were associated with increased reduction in HbA1c ([MD]-0.64%;-0.73 to -0.55) and FPG ([MD] -0.94; -1.12 to -0.76) levels, more patients in the combination therapy groups versus pioglitazone monotherapy groups had an A1c of < 7% ([OR]2.52; 2.18, 3.17) at the end of the studies, but was not associated with further reduction in higher risk of hypoglycaemia, edema, or any other system AEs. We also noticed that DPP-4 inhibitor and pioglitazone combination therapy were associated with better improvement of pancreatic β-cell function.

CONCLUSIONS

DPP-4 inhibitor and pioglitazone combination therapy provided better glycemic control, both according to HbA1c and FPG levels, than pioglitazone monotherapy. Safety analysis showed well tolerance of combination therapy, even in hypoglycemic and edema AEs. However, additional large-scale, high quality, long-term follow-up clinical trials are necessary to confirm its long-term effectiveness.

Oral formulation of DPP-4 inhibitor plus Quercetin improves metabolic homeostasis in type 1 diabetic rats

This study aimed to investigate the potential of an oral formulation (QV formulation) containing Quercetin and a Dipeptidyl Peptidase-4 Inhibitor (DPP-4 inhibitor), Vildagliptin, in improving metabolic homeostasis in type 1 diabetes model. Female albino Fischer rats were divided into four groups: untreated control animals (C), untreated diabetic animals (D), diabetic animals treated with QV formulation (DQV), and diabetic animals treated with insulin (DI). Diabetes was induced by injection of alloxan (135 mg kg body mass)^-1 and confirmed by glycemic test. After the 30-day treatment period, biochemical parameters were analyzed in the pancreas, liver, and serum. Histopathological changes in pancreatic tissue were examined by Hematoxyline & Eosin staining and the insulin content in the islet measured by immunohistochemistry with anti-insulin antibody. The glycogen content in the hepatocytes was quantified by Periodic Schiff Acid staining. The QV formulation reduced the glycemia, preserved the pancreatic architecture, increased insulin levels, furthermore ameliorated lipid profile and to promote higher survival rate of animals. Together, our data suggest that the QV formulation treatment was able to normalize metabolic homeostasis in type 1 diabetic rats.

DPP-4 is expressed in human pancreatic beta cells and its direct inhibition improves beta cell function and survival in type 2 diabetes

It has been reported that the incretin system, including regulated GLP-1 secretion and locally expressed DPP-4, is present in pancreatic islets. In this study we comprehensively evaluated the expression and role of DPP-4 in islet alpha and beta cells from non-diabetic (ND) and type 2 diabetic (T2D) individuals, including the effects of its inhibition on beta cell function and survival. Isolated islets were prepared from 25 ND and 18 T2D organ donors; studies were also performed with the human insulin-producing EndoC-βH1 cells. Morphological (including confocal microscopy), ultrastructural (electron microscopy, EM), functional (glucose-stimulated insulin secretion), survival (EM and nuclear dyes) and molecular (RNAseq, qPCR and western blot) studies were performed under several different experimental conditions. DPP-4 co-localized with glucagon and was also expressed in human islet insulin-containing cells. Furthermore, DPP-4 was expressed in EndoC-βH1 cells. The proportions of DPP-4 positive alpha and beta cells and DPP-4 gene expression were significantly lower in T2D islets. A DPP-4 inhibitor protected ND human beta cells and EndoC-βH1 cells against cytokine-induced toxicity, which was at least in part independent from GLP1 and associated with reduced NFKB1 expression. Finally, DPP-4 inhibition augmented glucose-stimulated insulin secretion, reduced apoptosis and improved ultrastructure in T2D beta cells. These results demonstrate the presence of DPP-4 in human islet alpha and beta cells, with reduced expression in T2D islets, and show that DPP-4 inhibition has beneficial effects on human ND and T2D beta cells. This suggests that DPP-4, besides playing a role in incretin effects, directly affects beta cell function and survival.

Effect of short-term treatment with sitagliptin or glibenclamide on daily glucose fluctuation in drug-naïve Japanese patients with type 2 diabetes mellitus

AIMS

To compare the effect of a dipeptidyl peptidase-4 inhibitor (DPP4-i) and a sulfonylurea (SU) on daily glucose fluctuation in drug-naïve Japanese patients with type 2 diabetes mellitus (T2DM).

MATERIALS AND METHODS

A total of 53 drug-naïve Japanese patients with T2DM (HbA1c, 7.0%-9.0%; fasting plasma glucose, 6.1 mmol/L or higher) were randomly assigned to either sitagliptin 50 mg qd or glibenclamide 2.5 mg per day (given in divided doses) in a 1:1 ratio. A continuous glucose monitoring (CGM) device was used to obtain 24-hour glucose profiles for each patient at baseline and at Week 2. The primary study endpoint was change from baseline in mean amplitude of glucose excursion (MAGE) during a 24-hour period. A key secondary endpoint was change from baseline in the standard deviation (SD) of 24-hour glucose levels.

RESULTS

After 2 weeks of treatment, a numerically greater reduction in MAGE from baseline was observed in the sitagliptin group compared with the glibenclamide group, but the between-treatment difference was not statistically significant (LS mean difference [95% CI]: -0.48 mmol/L [-1.31, 0.34]; P = .245). However, a significantly greater reduction in the change from baseline in SD was observed in the sitagliptin group compared with the glibenclamide group (LS mean difference [95% CI]: -0.33 mmol/L [-0.62, -0.03]; P = .029).

CONCLUSIONS

This study suggests that the DPP4 inhibitor sitagliptin has a greater ability to reduce daily glucose fluctuation than the SU glibenclamide in drug-naïve Japanese patients with T2DM. ClinicalTrials.gov: NCT02318693.

Soybean- and Lupin-Derived Peptides Inhibit DPP-IV Activity on In Situ Human Intestinal Caco-2 Cells and Ex Vivo Human Serum

Recent investigations have focused on food-derived peptides as novel natural inhibitors of dipeptidyl peptidase IV (DPP-IV), a new target for diabetes. This study aimed to optimize fast, sensitive, and cost-effective DPP-IV assays in situ on human intestinal Caco-2 cells and ex vivo on human serum. Both assays were applied to investigate the inhibitory activity of soy and lupin peptides. The best conditions for in situ DPP-IV activity in Caco-2 cells were obtained using 2-day cells and 50 µM Gly-Pro-AMC. Sitagliptin, used as reference inhibitor, showed a dose-dependent response with a 50% inhibition concentration (IC₅₀) of 0.6 µM. A lower IC₅₀ (0.2 µM) was obtained for sitagliptin on human serum incubated with the substrate for 24 h. Both assays were applied to assess the activity of Lup1 (LTFPGSAED) and Soy1 (IAVPTGVA) on DPP-IV. Lup1 and Soy1 inhibited DPP-IV in situ, with IC₅₀ values of of 207.5 and 223.2 µM, respectively, and maintained their inhibitory activity ex vivo on circulating DPP-IV with a slightly lower potency. These assays can be used to characterize the DPP-IV inhibitory activity of food-derived molecules more accurately than in vitro biochemical tests. This combined approach also considers their effects on the circulating form of DPP-IV, correlated to metabolic diseases.

Effects on the glucagon response to hypoglycaemia during DPP-4 inhibition in elderly subjects with type 2 diabetes: A randomized, placebo-controlled study

AIMS

Maintainance of glucagon response to hypoglycaemia is important as a safeguard against hypoglycaemia during glucose-lowering therapy in type 2 diabetes. During recent years, DPP-4 (dipeptidyl peptidase-4) inhibition has become more commonly used in elderly patients. However, whether DPP-4 inhibition affects the glucagon response to hypoglycaemia in the elderly is not known and was the aim of this study.

METHODS

In a single-centre, double-blind, randomized, placebo-controlled crossover study, 28 subjects with metformin-treated type 2 diabetes (17 male, 11 female; mean age, 74 years [range 65-86]; mean HbA1c, 51.5 mmol/mol [6.9%]) received sitagliptin (100 mg once daily) as add-on therapy or placebo for 4 weeks with a 4-week washout period in between. After each treatment period, the subjects underwent a standard breakfast test, followed by a 2-step hyperinsulinaemic hypoglycaemic clamp (target 3.5 and 3.0 mmol/L), followed by lunch.

RESULTS

Glucagon levels after breakfast and lunch, and the glucagon response at 3.5 mmol/L, were lower after sitagliptin than after placebo. However, the glucagon response to hypoglycaemia at 3.1 mmol/L did not differ significantly between the two. Similarly, the noradrenaline, adrenaline and cortisol responses were lower with sitagliptin than with placebo at 3.5 mmol/L, but not at 3.1 mmol/L glucose. Responses in pancreatic polypeptide did not differ between the two.

CONCLUSIONS

Elderly subjects with metformin-treated type 2 diabetes have lower glucagon levels at 3.5 mmol/L glucose, but maintain the glucagon response to hypoglycaemia at 3.1 mmol/L during DPP-4 inhibition, which safeguards against hypoglycaemia and may contribute to decreasing the risk of hypoglycaemia by DPP-4 inhibition in this age group.

Different glucagon effects during DPP-4 inhibition versus SGLT-2 inhibition in metformin-treated type 2 diabetes patients

AIMS

Previous studies have shown that dipeptidyl peptidase (DPP)-4 inhibition lowers glucagon levels whereas sodium-glucose co-transporter 2 (SGLT-2) inhibition increases them. This study evaluated the extent of these opposite effects in a direct comparative head-to-head study.

METHODS

In a single-centre, randomized study with a cross-over design, 28 metformin-treated patients with type 2 diabetes (T2D) (mean age, 63 years; baseline HbA1c, 6.8%) were treated with vildagliptin (50 mg twice daily) or dapagliflozin (10 mg once daily) for 2 weeks, with a 4-week wash-out period between the two separate treatments. After each treatment period, a meal test was undertaken, with measurements of islet and incretin hormones and 4-hour area under the curve (AUC) levels were estimated.

RESULTS

Fasting glucagon (35.6 ± 2.5 vs 39.4 ± 3.4 pmoL/L; P = .032) and postprandial glucagon (4-hour AUC_glucagon , 32.1 ± 2.3 vs 37.5 ± 2.7 nmoL/L min; P = .001) were ~15% lower after vildagliptin compared to dapagliflozin treatment. This was associated with stronger early (15 minute) C-peptide response and higher 4-hour AUC_C-peptide (P < .010), higher 4-hour AUC of the intact form of glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) (P < .001) and lower 4-hour AUC of total GIP and GLP-1 (P < .001).

CONCLUSION

Treatment with DPP-4 inhibition with vildagliptin results in 15% lower fasting and postprandial glucagon levels compared to SGLT-2 inhibition with dapagliflozin. DPP-4 inhibition also induces more rapid insulin secretion and higher levels of intact incretin hormones, resulting in stronger feedback inhibition of incretin hormone secretion than SGLT-2 inhibition.

Effect of race on the glycaemic response to sitagliptin: Insights from the Trial Evaluating Cardiovascular Outcomes with Sitagliptin (TECOS)

AIM

Pooled efficacy studies suggest that glycaemic responses to dipeptidyl-peptidase 4 inhibitors in type 2 diabetes are greatest in Asians, who may also respond better to alpha-glucosidase inhibitors. We assessed the glycaemic impact of sitagliptin by race in the Trial Evaluating Cardiovascular Outcomes with Sitagliptin (TECOS), and whether this was enhanced in Asians with concomitant acarbose therapy.

MATERIALS AND METHODS

TECOS enrolled 14 671 patients with type 2 diabetes, cardiovascular disease and HbA1c of 48-64 mmol/mol (6.5%-8.0%), and randomized them, double-blind, to sitagliptin or placebo. There were 3265 patients (22.3%) from Asian countries. Background glucose-lowering therapies were unaltered for the first 4 months post randomization unless clinically essential, facilitating comparison of sitagliptin-associated effects in self-identified East Asian, Other (South) Asian, White Caucasian, Hispanic, Black and Indigenous groups.

RESULTS

Median baseline HbA1c by race was 54 to 57 mmol/mol (7.1%-7.4%). Mean 4-month reduction in placebo-adjusted HbA1c was greatest in East Asians (-6.6 mmol/mol [-0.60%] vs ≤6.0 mmol/mol [≤0.55%] in other groups), with significantly greater reduction vs the 2 largest groups (White Caucasians, Other Asians; P < .0001) after adjustment for covariates. After the first 4 months, East and Other Asians were more likely to initiate additional oral therapy (metformin and/or sulfonylureas) than insulin vs White Caucasians (P < .0001). Acarbose use increased in the Asian patients, but no glycaemic interaction with allocated study medication was observed (adjusted P = .12).

CONCLUSIONS

The greatest initial reduction in HbA1c with sitagliptin in the TECOS population was in East Asians. No enhanced glycaemic effect was seen when sitagliptin was given with acarbose.

Unexplained reciprocal regulation of diabetes and lipoproteins

PURPOSE OF REVIEW

Type 2 diabetes is associated with a characteristic dyslipidemia that may exacerbate cardiovascular risk. The causes of, and the effects of new antihyperglycemia medications on, this dyslipidemia, are under investigation. In an unexpected reciprocal manner, lowering LDL-cholesterol with statins slightly increases the risk of diabetes. Here we review the latest findings.

RECENT FINDINGS

The inverse relationship between LDL-cholesterol and diabetes has now been confirmed by multiple lines of evidence. This includes clinical trials, genetic instruments using aggregate single nucleotide polymorphisms, as well as at least eight individual genes - HMGCR, NPC1L1, HNF4A, GCKR, APOE, PCKS9, TM6SF2, and PNPLA3 - support this inverse association. Genetic and pharmacologic evidence suggest that HDL-cholesterol may also be inversely associated with diabetes risk. Regarding the effects of diabetes on lipoproteins, new evidence suggests that insulin resistance but not diabetes per se may explain impaired secretion and clearance of VLDL-triglycerides. Weight loss, bariatric surgery, and incretin-based therapies all lower triglycerides, whereas SGLT2 inhibitors may slightly increase HDL-cholesterol and LDL-cholesterol.

SUMMARY

Diabetes and lipoproteins are highly interregulated. Further research is expected to uncover new mechanisms governing the metabolism of glucose, fat, and cholesterol. This topic has important implications for treating type 2 diabetes and cardiovascular disease.

The Vildagliptin Experience - 25 Years Since the Initiation of the Novartis Glucagon-like Peptide-1 Based Therapy Programme and 10 Years Since the First Vildagliptin Registration

The discovery of the incretin hormone glucagon like peptide-1 (GLP-1), and its usefulness in the treatment of type 2 diabetes mellitus (T2DM) followed by the finding that dipeptidyl peptidase-4 (DPP-4) inhibition prevents GLP-1 inactivation, led to the discovery of DPP-728. In 1999, studies with DPP-728 established the first proof-of-concept that DPP-4 inhibition improves glycaemic control in patients with T2DM. Further efforts to improve the binding kinetics of DPP-728 resulted in the discovery of vildagliptin (LAF237). In the last 20 years, a plethora of studies conducted by Novartis in collaboration with external investigators has demonstrated the mechanism of action of vildagliptin and its efficacy as monotherapy and as an add-on therapy for patients with T2DM. The studies establish that vildagliptin is a selective DPP-4 inhibitor that blocks GLP-1 and glucose-dependent insulinotropic polypeptide (GIP) inactivation, thereby prolonging their action, resulting in improved glycaemic control. This review aims to discuss the discovery and development of vildagliptin, with an emphasis on mechanism of action and clinical efficacy.

Relationship Between Duration of Type 2 Diabetes and Effectiveness of DPP-4 Inhibitor Versus Sulfonylurea as Add-on Therapy: A Post Hoc Analysis

INTRODUCTION

To assess the impact of duration of type 2 diabetes on glucose-lowering effectiveness of the dipeptidyl peptidase-4 (DPP-4) inhibitor vildagliptin versus sulfonylureas (SUs) in a real-life setting.

METHODS

Data were extracted from the large 1-year, observational EDGE study (N = 45,868). Patients receiving either DPP-4 inhibitor or any SU as add-on to monotherapy were selected (N = 36,164). Impact of the disease duration on change in glycated hemoglobin (HbA1c) levels was evaluated by using a linear multiple regression model. Descriptive statistics assessed the proportion of patients achieving the composite endpoint (HbA1c <7.0%; 53.0 mmol/mol without hypoglycemia or weight gain), stratified by diabetes duration.

RESULTS

At baseline, the overall mean (±SD) type 2 diabetes duration was 5.4 ± 5.24 years, and HbA1c was 8.2 ± 1.33% (66.0 ± 14.5 mmol/mol). HbA1c lowering was directly proportional to the baseline HbA1c (-0.69 per unit; 95% CI -0.696, -0.681; p < 0.0001) and inversely proportional to the disease duration (0.01 per year; 95% CI 0.01, 0.013). There was an increased loss of β-cell function (less pronounced HbA1c drop with increasing disease duration) in patients treated with SU-based regimens (0.025; 95% CI 0.022, 0.027) compared with vildagliptin-based regimens (0.005; 95% CI 0.003, 0.007), with the mean adjusted difference being 0.10 (95% CI -0.122, -0.092; p < 0.0001). Consistently, a higher proportion of patients achieved the composite endpoint with vildagliptin over the diabetes duration (less than 2 to more than 10 years).

CONCLUSION

Vildagliptin demonstrated less dependency on the duration of type 2 diabetes, whereas the effectiveness of SUs diminished faster with increasing duration of the disease in a real-life setting.

FUNDING

Novartis Pharma AG.

Comparative safety for cardiovascular outcomes of DPP-4 inhibitors versus glimepiride in patients with type 2 diabetes: A retrospective cohort study

Concerns about the cardiovascular safety of dipeptidyl peptidase-4 (DPP-4) inhibitors persist. This study sought to determine whether there is a differential risk of hospitalization for cardiovascular diseases (CVDs) between DPP-4 inhibitors and glimepiride.We conducted this retrospective cohort study by using the Korean National Health Insurance Service database from December 1, 2008, to December 31, 2013. The study subjects were new users of DPP-4 inhibitors or glimepiride for type 2 diabetes. Outcome was defined as hospitalization for CVDs, including angina pectoris, myocardial infarction, transient cerebral ischemic attack, heart failure, or cerebrovascular disease or any procedure involving coronary artery bypass grafting or percutaneous coronary intervention. We used a Cox proportional hazard model to estimate the adjusted hazard ratios (aHRs) and their 95% confidence intervals (CIs), to assess the risk of CVDs associated with the use of DPP-4 inhibitors compared with glimepiride.The cohort consisted of 1,045,975 patients, with 6504 in the DPP-4 inhibitors group and 13,447 in the glimepiride group. No significant increased risk of total CVDs was found (aHR, 0.87; 95% CI, 0.75-1.01) in the DPP-4 inhibitors versus glimepiride group. A decreased risk of hospitalization for CVDs was found among patients with a history of visit for CVDs (aHR, 0.73; 95% CI, 0.56-0.97) or with >2.5 years' duration of type 2 diabetes (aHR, 0.77; 95% CI, 0.66-0.91) in the DPP-4 inhibitors versus glimepiride group.DPP-4 inhibitors did not increase cardiovascular risk compared with glimepiride regardless of CVD history and diabetes duration.

Early Combination Therapy with Oral Glucose-Lowering Agents in Type 2 Diabetes

Despite the considerable burden of disease associated with type 2 diabetes mellitus (T2DM), most patients are not at, or are unable to achieve, recommended glycemic targets. This is partly because of the relentless progressive nature of the disease, but it may also be attributable to the current diabetes treatment paradigm. The recommended stepwise approach may lead to frequent early treatment failure with prolonged periods of elevated glucose as a consequence of clinical inertia and delays in achieving optimal glycemic control. Thus, it is most appropriate to consider the current treatment paradigm for T2DM in the context of a more aggressive initial therapy with early combination therapy. Current guidelines advise that initial combination therapy should be used for patients presenting with elevated glycated hemoglobin (HbA_1c). However, several studies and recent meta-analyses suggest a potential benefit from initial combination therapy on glycemic outcomes in diabetes compared with metformin monotherapy across a wide range of baseline HbA_1c levels. Indeed, combination therapy can increase the number of patients achieving glycemic goals, and the newer glucose-lowering agents may reduce the risk of hypoglycemia and body weight gain. Moreover, our improving understanding of the complex pathophysiology of T2DM and the availability of treatments tackling specific mechanisms contributing to hyperglycemia should lead to more pathophysiologically sound combination therapy. We discuss the rationale behind and evidence for early combination therapy as well as what is needed in the future to better understand its potential.

Efficacy and safety of adding evogliptin versus sitagliptin for metformin-treated patients with type 2 diabetes: A 24-week randomized, controlled trial with open label extension

AIMS

This trial consisted of a 24-week multicentre, randomized, double-blind, double-dummy, active-controlled study and a 52-week open label extension study to assess the efficacy and safety of evogliptin, a novel dipeptidyl peptidase-4 inhibitor, compared to sitagliptin in patients with type 2 diabetes who have inadequate glycaemic control with metformin alone.

METHODS

Adult patients with type 2 diabetes mellitus (N = 222) with HbA1c 6.5% to 11% who were receiving stable doses of metformin (≥1000 mg/d) were randomized 1:1 to add-on evogliptin 5 mg (N = 112) or sitagliptin 100 mg (N = 110) once daily for 24 weeks. The primary efficacy analysis consisted of a comparison of the change from baseline HbA1c at week 24. Non-inferiority was concluded if the upper limit of the 2-sided 95% confidence interval for the HbA1c difference between treatments was <0.35%.

RESULTS

Mean changes in HbA1c following addition of evogliptin or sitagliptin were -0.59% and -0.65%, respectively. The between-group difference was 0.06% (2-sided 95% confidence interval, -0.10 to 0.22), demonstrating non-inferiority. After the 52-week treatment, evogliptin caused a persistently decreased level of HbA1c (-0.44% ± 0.65%, P  < .0001). In general, both treatments were well tolerated, with incidences and types of adverse events comparable between the two groups. Hypoglycaemic events, mostly mild, were reported in 0.9% of patients treated with evogliptin and in 2.8% of patients treated with sitagliptin for 24 weeks.

CONCLUSIONS

Evogliptin 5 mg added to metformin therapy effectively improved glycaemic control and was non-inferior to sitagliptin and well tolerated in patients with type 2 diabetes mellitus that was inadequately controlled by metformin alone.

DPP-4 inhibitor treatment: β-cell response but not HbA1c reduction is dependent on the duration of diabetes

INTRODUCTION

Dipeptidyl peptidase-4 (DPP-4) inhibitors reduce hyperglycemia in patients with type 2 diabetes mellitus (T2DM) by enhancing insulin and suppressing glucagon secretion. Since T2DM is associated with progressive loss of β-cell function, we hypothesized that the DPP-4 inhibitor action to improve β-cell function would be attenuated with longer duration of T2DM.

METHODS

Data from six randomized, placebo-controlled trials of 24 weeks duration, where β-cell response to vildagliptin 50 mg twice daily was assessed, were pooled. In each study, the insulin secretory rate relative to glucose (ISR/G 0-2h) during glucose load (standard meal or oral glucose tolerance test) was assessed at baseline and end of study. The mean placebo-subtracted difference (PSD) in the change in ISR/G 0-2h from baseline for each study was evaluated as a function of age, duration of T2DM, baseline ISR/G 0-2h, glycated hemoglobin (HbA_1c), fasting plasma glucose, body mass index, and mean PSD in the change in HbA_1c from baseline, using univariate model.

RESULTS

There was a strong negative association between the PSD in the change from baseline in ISR/G 0-2h and duration of T2DM (r= -0.89, p<0.02). However, there was no association between the PSD in the change from baseline in ISR/G 0-2h and the PSD in the change from baseline in HbA_1c (r=0.33, p=0.52). None of the other characteristics were significantly associated with mean PSD change in ISR/G 0-2h.

CONCLUSION

These findings indicate that the response of the β-cell, but not the HbA_1c reduction, with vildagliptin is dependent on duration of T2DM. Further, it can be speculated that glucagon suppression may become the predominant mechanism via which glycemic control is improved when treatment with a DPP-4 inhibitor, such as vildagliptin, is initiated late in the natural course of T2DM.

Emerging use of combination therapies for the management of type 2 diabetes - focus on saxagliptin and dapagliflozin

AIMS

The aim of this article is to review the safety and efficacy data of dapagliflozin, saxagliptin, and their combination in the management of patients with type 2 diabetes. Evidence for the use of the single-tablet combination formulation is also presented.

METHODS

A nonsystematic literature review was performed using the Ovid, PubMed, and Google Scholar databases.

RESULTS

The addition of dapagliflozin/saxagliptin to metformin can lower mean hemoglobin A1c by as much as 1.47% and lead to weight loss of 0.5-2.0 kg. The risk of genital infections with combination therapy is lower than observed with dapagliflozin alone, suggestive of a protective effect. Adverse event risk at 52-week follow-up was not increased beyond that seen with either monotherapy.

CONCLUSION

Dapagliflozin/saxagliptin combination is generally well tolerated and is an effective tool in helping patients with diabetes improve glycemic control.

Peptides Derived from Soy and Lupin Protein as Dipeptidyl-Peptidase IV Inhibitors: In Vitro Biochemical Screening and in Silico Molecular Modeling Study

Dipeptidyl peptidase IV (DPP-IV) is a new molecular target correlated with the development of type 2 diabetes. Literature describes the identification of some inhibitory peptides from the hydrolysis of different food proteins. This article reports a study on six peptides from soybean and lupin proteins, i.e., Soy 1 (IAVPTGVA), Soy 2 (YVVNPDNDEN), Soy 3 (YVVNPDNNEN), Lup 1 (LTFPGSAED), Lup 2 (LILPKHSDAD), and Lup 3 (GQEQSHQDEGVIVR), which were screened for their capacity to inhibit the activity of DPP-IV, using an in vitro bioassay against human recombinant DPP-IV. Two peptides Soy 1 and Lup 1 resulted to be efficient inhibitors with IC50 values equal to 106 and 228 μM, respectively. A molecular docking analysis predicted the key molecular interactions, stabilizing the active peptides within DPP-IV enzyme. Soy and lupin proteins may be sources of DPP-IV inhibitory peptides potentially useful for the prevention of type 2 diabetes.

C-Peptide Levels Predict the Effectiveness of Dipeptidyl Peptidase-4 Inhibitor Therapy

Background. Our aim was to define the conditions that affect therapeutic success when dipeptidyl peptidase-4 (DPP-4) inhibitor is added to metformin monotherapy. Materials and Methods. We reviewed the medical records of 56 patients who had received DPP-4 inhibitor as an add-on to metformin monotherapy and evaluated their response in the first year of therapy. Fasting blood glucose (FBG), HbA1c, C-peptide, and weight of the patients were recorded at 3-month intervals during the first year of treatment. Results. Patients who added DPP-4 inhibitor to metformin monotherapy had significant weight loss (P = 0.004) and FBG and HbA1c levels were significantly lowered during the first 6 months (both P < 0.001). Baseline levels of C-peptide were predictive for success of the treatment (P = 0.02), even after correction for confounding factors, for example, age, gender, or BMI (P = 0.03). Duration of diabetes was not a predictor of response to treatment (P = 0.60). Conclusion. Our study demonstrates that in patients having inadequate glycemic control, the addition of a DPP-4 inhibitor as a second oral agent to metformin monotherapy provides better glycemic control, protects β-cell reserves, and does not cause weight gain. These effects depend on baseline C-peptide levels.