The Place of Dipeptidyl Peptidase-4 Inhibitors in Type 2 Diabetes Therapeutics: A "Me Too" or "the Special One" Antidiabetic Class?

Role of anagliptin, a dipeptidyl peptidase-4 inhibitor, in managing type 2 diabetes: A systematic review and meta-analysis

BACKGROUND

No comprehensive meta-analysis has examined and consolidated the effectiveness and safety of anagliptin in treating type 2 diabetes mellitus (T2D). To bridge this knowledge gap, we undertook this meta-analysis.

METHODS

Randomized controlled trials involving patients with T2D receiving anagliptin were sought after through electronic databases. The control arm consisted of either an active comparator (active control group [ACG]) or a placebo (passive control group [PCG]). The primary outcome was glycated hemoglobin (HbA1c), with secondary outcomes including fasting plasma glucose (FPG) and lipid profiles and adverse events.

RESULTS

From the 226 articles first examined, 10 randomized controlled trials with 970 participants were analyzed. Reductions in HbA1c (mean difference [MD]: -0.03%, 95% confidence interval [CI]: -0.14 to 0.14, P = .51, I2 = 9%) and FPG (MD: 0.03 mmol/L, 95% CI: -0.30 to 0.35, P = .87, I2 = 42%) were similar in the anagliptin group and ACG. Anagliptin reduced FPG better than placebo (MD: -1.25 mmol/L, 95% CI: -1.87 to -0.64, P < .0001, I2 = 0%). Sufficient data were unavailable to analyze the HbA1c lowering with anagliptin versus placebo. Among the lipid parameters, changes in total cholesterol, high-density lipoprotein cholesterol, apolipoprotein B48, and apolipoprotein B100 were identical between the anagliptin and control groups (PCG and ACG). Anagliptin was better than ACG at lowering low-density lipoprotein cholesterol but not as good at lowering triglyceride. Adverse events were infrequent and similar in the anagliptin and control groups (PCG and ACG).

CONCLUSION

Anagliptin positively affects glucose control and is safe for managing T2D. Its low-density lipoprotein cholesterol-lowering effect warrants further investigation.

Recent advances and structure-activity relationship studies of DPP-4 inhibitors as anti-diabetic agents

Diabetes mellitus (DM) is one of the largest public health problems worldwide and in the last decades various therapeutic targets have been investigated. For the treatment of type-2 DM (T2DM), dipeptidyl peptidase-4 (DPP-4) is one of the well reported target and has established safety in terms of cardiovascular complexicity. Preclinical and clinical studies using DPP-4 inhibitors have demonstrated its safety and effectiveness and have lesser risk of associated hypoglycaemic effect making it suitable for elderly patients. FDA has approved a number of structurally diverse DPP-4 inhibitors for clinical use. The present manuscript aims to focus on the well reported hybrid and non-hybrid analogues and their structural activity relationship (SAR) studies. It aims to provide structural insights for this class of compounds pertaining to favourable applicability of selective DPP-4 inhibitors in the treatment of T2DM.

Overview of Ethnobotanical-Pharmacological Studies Carried Out on Medicinal Plants from the Serra da Estrela Natural Park: Focus on Their Antidiabetic Potential

The Serra da Estrela Natural Park (NPSE) in Portugal stands out as a well-preserved region abundant in medicinal plants, particularly known for their pharmaceutical applications in diabetes prevention and treatment. This comprehensive review explores these plants' botanical diversity, traditional uses, pharmacological applications, and chemical composition. The NPSE boast a rich diversity with 138 medicinal plants across 55 families identified as traditionally and pharmacologically used against diabetes globally. Notably, the Asteraceae and Lamiaceae families are prevalent in antidiabetic applications. In vitro studies have revealed their significant inhibition of carbohydrate-metabolizing enzymes, and certain plant co-products regulate genes involved in carbohydrate metabolism and insulin secretion. In vivo trials have demonstrated antidiabetic effects, including glycaemia regulation, insulin secretion, antioxidant activity, and lipid profile modulation. Medicinal plants in NPSE exhibit various activities beyond antidiabetic, such as antioxidant, anti-inflammatory, antibacterial, anti-cancer, and more. Chemical analyses have identified over fifty compounds like phenolic acids, flavonoids, terpenoids, and polysaccharides responsible for their efficacy against diabetes. These findings underscore the potential of NPSE medicinal plants as antidiabetic candidates, urging further research to develop effective plant-based antidiabetic drugs, beverages, and supplements.

Expert eValuation of Efficacy and Rationality of Vildagliptin "EVER-Vilda": An Indian Perspective

Vildagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor is effective in reducing HbA1c levels in patients with type 2 diabetes (T2DM) when administered as monotherapy, dual or triple combination therapy. In India, Vildagliptin is commonly prescribed in T2DM patients because it reduces mean amplitude of glycemic excursion (MAGE), has lower risk of hypoglycemia and is weight neutral. Early combination therapy with vildagliptin and metformin is effective and well-tolerated in patients with T2DM, regardless of age or ethnicity. In view of already existing data on vildagliptin and the latest emerging clinical evidence, a group of endocrinologists, diabetologists and cardiologists convened for an expert group meeting to discuss the role and various combinations of vildagliptin in T2DM management. This practical document aims to guide Physicians and Specialists regarding the different available strengths and formulations of vildagliptin for the initiation and intensification of T2DM therapy.

Efficacy and Safety of Omarigliptin, a Novel Once-Weekly Dipeptidyl Peptidase-4 Inhibitor, in Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis

BACKGRUOUND

No recent meta-analysis has holistically analyzed and summarized the efficacy and safety of omarigliptin in type 2 diabetes mellitus (T2DM). We conducted a meta-analysis to address this knowledge gap.

METHODS

Electronic databases were searched to identify randomized controlled trials (RCTs) that included patients with T2DM who received omarigliptin in the intervention arm. The control arm consisted of either a placebo (passive control group [PCG]) or an active comparator (active control group [ACG]). The primary outcome assessed was changes in hemoglobin A1c (HbA1c), while secondary outcomes included variations in glucose levels, achievement of glycemic targets, adverse events (AEs), and hypoglycemic events.

RESULTS

From 332 initially screened articles, data from 16 RCTs involving 8,804 subjects were analyzed. Omarigliptin demonstrated superiority over placebo in reducing HbA1c levels (mean difference, -0.58%; 95% confidence interval, -0.75 to -0.40; P<0.00001; I2=91%). Additionally, omarigliptin outperformed placebo in lowering fasting plasma glucose, 2-hour postprandial glucose, and in the percentage of participants achieving HbA1c levels below 7.0% and 6.5%. The glycemic efficacy of omarigliptin was similar to that of the ACG across all measures. Although the omarigliptin group experienced a higher incidence of hypoglycemic events compared to the PCG, the overall AEs, serious AEs, hypoglycemia, and severe hypoglycemia were comparable between the omarigliptin and control groups (PCG and ACG).

CONCLUSION

Omarigliptin has a favorable glycemic efficacy and safety profile for managing T2DM.

Network pharmacology-based elucidation of bioactive compounds and experimental exploration of antidiabetic mechanisms of Hydrolea zeylanica

This investigation systematically explored the underlying antidiabetic mechanism of Hydrolea zeylanica (HZH) by the approach of network pharmacology and experimental validation in restoring glucose homeostasis, and inflammation in high fat diet fed-streptozotocin (HFD/STZ)-induced type II diabetes (T2DM) rats. Network pharmacology analysis was conducted on 32 bioactive components of HZH. In silico ADME prediction, and physicochemical analysis of 32 compounds were used to assess their drug-likeness. Common targets between selected compounds, and T2DM were subjected for GO enrichment. Compound-target-pathway network was predicted with selected compounds and targets. HZH (300 and 400 mg/kg) were considered for GLUTs expression, and inflammation cytokines in T2DM rats. Network pharmacology showed the core relationship between 13 selected compounds, and 194 key target genes in insulin resistance, type II diabetes mellitus, insulin signaling pathways in T2DM. AKT1, AKT2, GSK3B, IL6, INSR, MAPK8, PPARA, GLUT1, GLUT2, GLUT4 were observed as the key targets in PPI network. HZH-400 significantly restored glucose homeostasis, and inflammatory markers in T2DM rats. It altered GLUT2, GLUT4 expression in liver, and skeletal muscle to normal. Bioactive compounds of HZH were found to control blood sugar level by modulating insulin resistance, type II diabetes mellitus, insulin signaling pathways, and glucose homeostasis, which in turn improved glucose uptake, insulin production in diabetes as shown in network pharmacology and glucose transporter expression studies.

Early treatment with dipeptidyl-peptidase 4 inhibitors reduces glycaemic variability and delays insulin initiation in type 2 diabetes: A propensity score-matched cohort study

AIMS

To examine whether early treatment intensification using dipeptidyl-peptidase 4 inhibitors (DPP4i) delays insulin initiation in Chinese patients diagnosed with type 2 diabetes for less than 5 years.

MATERIALS AND METHODS

In a territory-wide prospective cohort study, patients with type 2 diabetes initiating DPP4i at diabetes duration <2 years (early intensification) and 3-5 years (late intensification) were matched using 1:1 propensity-score matching (n = 908 in each arm). We used Cox regression to compare the risk of insulin initiation between the two groups. We explored the interactive and mediation effects of glycated haemoglobin (HbA1c) variability score (HVS), defined as the percentage of HbA1c varying by ≥0.5% compared with preceding values.

RESULTS

Of 1816 patients (60.7% men, mean age 54.4 ± 11.9 years), 92.4% and 71.9% were treated with metformin and sulphonylureas respectively at DPP4i initiation. Early DPP4i intensification [hazard ratio (HR) 0.71, (95% CI 0.58-0.68)] and low HVS (<50%) (HR = 0.40, 0.33-0.50) were associated with delayed insulin initiation during a median 4.08 years of follow-up. Early intensification with low HVS had the lowest risk versus late intensification with high HVS (HR = 0.30, 0.22-0.40) (pinteraction  = 0.013). HVS mediated 19.5% of the total effect of early DPP4i intensification on delaying insulin initiation. The late and early intensification groups had similar HbA1c at month 0 (8.4 ± 1.3% vs. 8.4 ± 1.5%) and month 3 (7.6 ± 1.2% vs. 7.6 ± 1.3%) after DPP4i initiation. By month 12, HbA1c in the late intensification group deteriorated (7.9 ± 1.4%) but remained stable in the early intensification group (7.6 ± 1.4%, p = 0.001) with persistent between-group difference over 72 months (8.2 ± 1.7% vs. 7.7 ± 1.6%, p = 0.001).

CONCLUSIONS

In type 2 diabetes, early DPP4i intensification delayed insulin initiation, partially explained by reduced glycaemic variability.

A Quantitative Systems Pharmacology Model of the Incretin Hormones GIP and GLP1, Glucagon, Glucose, Insulin, and the Small Molecule DPP-4 Inhibitor, Linagliptin

In the current study, we established a comprehensive quantitative systems pharmacology (QSP) model using linagliptin as the model drug, where drug disposition, drug intervention on dipeptidyl peptidase-4 (DPP-4), glucose-dependent insulinotropic peptide (GIP), Glucagon-like peptide-1 (GLP-1), glucagon, glucose, and insulin are integrated together with the cross talk and feedback loops incorporated among the whole glycemic control system. In the final linagliptin QSP model, the complicated disposition of linagliptin was characterized by a 2-compartment pharmacokinetic (PK) model with an enterohepatic cycling (EHC) component as well as target-mediated drug disposition (TMDD) processes occurring in both tissues and plasma, and the inhibitory effect of linagliptin on DPP-4 was determined by the linagliptin-DPP-4 complex in the central compartment based on target occupancy principle. The integrated GIP-GLP1-glucagon-glucose-insulin system contains five indirect response models as the "skeleton" structure with 12 feedback loops incorporated within the glucose control system. Our model adequately characterized the substantial nonlinear PK of linagliptin, time course of DPP-4 inhibition, as well as the kinetics of GIP, GLP-1, glucagon, and glucose simultaneously in humans. Our model provided valuable insights on linagliptin pharmacokinetics/pharmacodynamics and complicated glucose homeostasis. Since the glucose regulation modeling framework within the QSP model is "drug-independent", our model can be easily adopted by others to evaluate the effect of other DPP-4 inhibitors on the glucose control system. In addition, our QSP model, which contains more components than other reported glucose regulation models, can potentially be used to evaluate the effect of combination antidiabetic therapy targeting different components of glucose control system.

Risk Stratification in People with Diabetes for Fasting During Ramadan: Consensus from Arabic Association for the Study of Diabetes and Metabolism

BACKGROUND

Current international guidelines recommend a pre-Ramadan risk assessment for people with diabetes (PwDM) who plan on fasting during the Holy month. However, a comprehensive risk assessment-based recommendation for the management of PwDM intending to fast is still controversial. Therefore, the Arabic Association for the Study of Diabetes and Metabolism (AASD) developed this consensus to provide further insights into risk stratification in PwDM intending to fast during Ramadan.

METHODS

The present consensus was based on the three-step modified Delphi method. The modified Delphi method is based on a series of voting rounds and in-between meetings of the expert panel to reach agreements on the statements that did not reach the consensus level during voting. The panel group comprised professors and consultants in endocrinology (both adult and pediatric). Other members included experts in the fields of cardiovascular medicine, nephrology, ophthalmology, and vascular surgery, affiliated with academic institutions in Egypt.

RESULT

In PwDM who intend to fast during Ramadan, risk stratification is crucial to optimize patient outcomes and prevent serious complications. The present consensus provides risk assessment of those living with diabetes according to several factors, including the type of diabetes, presence, and severity of complications, number of fasting hours, and other socioeconomic factors. According to their risk factors, patients were classified into four categories (very high, high, moderate, and low risk).

CONCLUSION

Future research is warranted due to the controversial literature regarding the impact of fasting on certain comorbidities.

Emerging therapeutic options in the management of diabetes: recent trends, challenges and future directions

Diabetes is a serious health issue that causes a progressive dysregulation of carbohydrate metabolism due to insufficient insulin hormone, leading to consistently high blood glucose levels. According to the epidemiological data, the prevalence of diabetes has been increasing globally, affecting millions of individuals. It is a long-term condition that increases the risk of various diseases caused by damage to small and large blood vessels. There are two main subtypes of diabetes: type 1 and type 2, with type 2 being the most prevalent. Genetic and molecular studies have identified several genetic variants and metabolic pathways that contribute to the development and progression of diabetes. Current treatments include gene therapy, stem cell therapy, statin therapy, and other drugs. Moreover, recent advancements in therapeutics have also focused on developing novel drugs targeting these pathways, including incretin mimetics, SGLT2 inhibitors, and GLP-1 receptor agonists, which have shown promising results in improving glycemic control and reducing the risk of complications. However, these treatments are often expensive, inaccessible to patients in underdeveloped countries, and can have severe side effects. Peptides, such as glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), are being explored as a potential therapy for diabetes. These peptides are postprandial glucose-dependent pancreatic beta-cell insulin secretagogues and have received much attention as a possible treatment option. Despite these advances, diabetes remains a major health challenge, and further research is needed to develop effective treatments and prevent its complications. This review covers various aspects of diabetes, including epidemiology, genetic and molecular basis, and recent advancements in therapeutics including herbal and synthetic peptides.

Milestones in the journey towards addressing obesity; Past trials and triumphs, recent breakthroughs, and an exciting future in the era of emerging effective medical therapies and integration of effective medical therapies with metabolic surgery

The 21st century is characterized by an increasing incidence and prevalence of obesity and the burden of its associated comorbidities, especially cardiometabolic diseases, which are reaching pandemic proportions. In the late '90s, the "black box" of adipose tissue and energy homeostasis was opened with the discovery of leptin, transforming the adipose tissue from an "inert fat-storage organ" to the largest human endocrine organ and creating the basis on which more intensified research efforts to elucidate the pathogenesis of obesity and develop novel treatments were based upon. Even though leptin was eventually not proven to be the "standalone magic bullet" for the treatment of common/polygenic obesity, it has been successful in the treatment of monogenic obesity syndromes. Additionally, it shifted the paradigm of treating obesity from a condition due to "lack of willpower" to a disease due to distinct underlying biological mechanisms for which specific pharmacotherapies would be needed in addition to lifestyle modification. Subsequently, the melanocortin pathway proved to be an equally valuable pathway for the pharmacotherapy of obesity. Melanocortin receptor agonists have recently been approved for treating certain types of syndromic obesity. Other molecules- such as incretins, implicated in energy and glucose homeostasis- are secreted by the gastrointestinal tract. Glucagon-like peptide 1 (GLP-1) is the most prominent one, with GLP-1 analogs approved for common/polygenic obesity. Unimolecular combinations with other incretins, e.g., GLP-1 with gastric inhibitory polypeptide and/or glucagon, are expected to be approved soon as more effective pharmacotherapies for obesity and its comorbidities. Unimolecular combinations with other compounds and small molecules activating the receptors of these molecules are currently under investigation as promising future pharmacotherapies. Moreover, metabolic and bariatric surgery has also demonstrated impressive results, especially in the case of morbid obesity. Consequently, this broadening therapeutic armamentarium calls for a well-thought-after and well-coordinated multidisciplinary approach, for instance, through cardiometabolic expertise centers, that would ideally address effectively and cost-effectively obesity and its comorbidities, providing tangible benefits to large segments of the population.

The Real DAPSI: A Real-World Retrospective Study on Assessing the Efficacy and Safety of a Fixed-Dose Combination of Dapagliflozin and Sitagliptin in the Indian Population

Introduction Type 2 diabetes mellitus (T2DM) is a chronic metabolic disorder affecting millions of individuals worldwide. Effective management of T2DM is crucial to prevent complications. Dapagliflozin and sitagliptin are oral anti-diabetic agents that have been shown to provide synergistic effects in controlling blood glucose levels. However, there is limited data on the efficacy and safety of the dapagliflozin-sitagliptin fixed-dose combination (FDC) in the Indian population. This study aimed to evaluate the real-world effectiveness and safety of the dapagliflozin-sitagliptin FDC in the Indian population. Methods This was a retrospective study conducted at healthcare centers in India. The study included patients with T2DM who were prescribed a FDC of dapagliflozin and sitagliptin. Data were collected from the medical health records of patients, including demographics, baseline glycated hemoglobin (HbA1c), blood glucose levels, BMI, blood pressure, and adverse events. The primary outcome was the change in HbA1c, postprandial plasma glucose (PPG), and fasting plasma glucose (FPG) from baseline to 12 weeks after treatment initiation. Results A total of 358 patients were included in the study, with a mean age of 56.2 years. The majority of the patients were male (68.2%), and the mean baseline HbA1c was 8.9 ± 0.87%. After 12 weeks of treatment with dapagliflozin and sitagliptin, there was a significant reduction in HbA1c levels from 8.9 to 7.2 (p <0.0001). There was also a significant reduction in fasting blood glucose levels from 178.8 to 124.0 (p <0.0001) and postprandial blood glucose levels from 273.9 to 176.0 (p <0.0001). There were no serious adverse events reported during the study period. Conclusion The FDC of dapagliflozin and sitagliptin is effective and safe in reducing blood glucose levels and BMI in the Indian population with T2DM. This real-world retrospective study provides valuable insights into the clinical effectiveness and safety of dapagliflozin-sitagliptin FDC in the Indian population. These findings highlight the potential benefits of this combination therapy in managing T2DM and pave the way for optimized treatment strategies and improved patient outcomes in the Indian healthcare landscape. Clinicians may consider dapagliflozin-sitagliptin FDC as a viable treatment option for T2DM patients.

Exploring the Potential of Antidiabetic Agents as Therapeutic Approaches for Alzheimer's and Parkinson's Diseases: A Comprehensive Review

Alzheimer's and Parkinson's are two prevalent neurodegenerative disorders with significant societal and healthcare burdens. The search for effective therapeutic approaches to combat these diseases has led to growing interest in exploring the potential of antidiabetic agents. This comprehensive review aims to provide a detailed overview of the current literature on using antidiabetic agents as therapeutic interventions for Alzheimer's and Parkinson's diseases. We discuss the underlying pathological mechanisms of these neurodegenerative diseases, including protein misfolding, inflammation, oxidative stress, and mitochondrial dysfunction. We then delve into the potential mechanisms by which antidiabetic agents may exert neuroprotective effects, including regulation of glucose metabolism and insulin signaling, anti-inflammatory effects, modulation of oxidative stress, and improvement of mitochondrial function and bioenergetics. We highlight in vitro, animal, and clinical studies that support the potential benefits of antidiabetic agents in reducing disease pathology and improving clinical outcomes. However, we also acknowledge these agents' limitations, variability in treatment response, and potential side effects. Furthermore, we explore emerging therapeutic targets and novel approaches, such as glucagon-like peptide-1 receptor (GLP-1R) agonists, insulin sensitizer drugs, neuroinflammation-targeted therapies, and precision medicine approaches. The review concludes by emphasizing the need for further research, including large-scale clinical trials, to validate the efficacy and safety of antidiabetic agents in treating Alzheimer's and Parkinson's disease. The collaboration between researchers, clinicians, and pharmaceutical companies is essential in advancing the field and effectively treating patients affected by these debilitating neurodegenerative disorders.

Repurposing drugs targeting metabolic diseases for cancer therapeutics

Hurdles in the identification of new drugs for cancer treatment have made drug repurposing an increasingly appealing alternative. The approach involves the use of old drugs for new therapeutic purposes. It is cost-effective and facilitates rapid clinical translation. Given that cancer is also considered a metabolic disease, drugs for metabolic disorders are being actively repurposed for cancer therapeutics. In this review, we discuss the repurposing of such drugs approved for two major metabolic diseases, diabetes and cardiovascular disease (CVD), which have shown potential as anti-cancer treatment. We also highlight the current understanding of the cancer signaling pathways that these drugs target.

Investigating Potential GLP-1 Receptor Agonists in Cyclopeptides from Pseudostellaria heterophylla, Linum usitatissimum, and Drymaria diandra, and Peptides Derived from Heterophyllin B for the Treatment of Type 2 Diabetes: An In Silico Study

GLP-1 receptor agonists stimulate GLP-1R to promote insulin secretion, whereas DPP4 inhibitors slow GLP-1 degradation. Both approaches are incretin-based therapies for T2D. In addition to GLP-1 analogs, small nonpeptide GLP-1RAs such as LY3502970, TT-OAD2, and PF-06882961 have been considered as possible therapeutic alternatives. Pseudostellaria heterophylla, Linum usitatissimum, and Drymaria diandra are plants rich in cyclopeptides with hypoglycemic effects. Our previous study demonstrated the potential of their cyclopeptides for DPP4 inhibition. Reports of cyclic setmelanotide as an MC4R (GPCR) agonist and cyclic α-conotoxin chimeras as GLP-1RAs led to docking studies of these cyclopeptides with GLP-1R. Heterophyllin B, Pseudostellarin B, Cyclolinopeptide B, Cyclolinopeptide C, Drymarin A, and Diandrine C are abundant in these plants, with binding affinities of −9.5, −10.4, −10.3, −10.6, −11.2, and −11.9 kcal/mol, respectively. The configuration they demonstrated established multiple hydrogen bonds with the transmembrane region of GLP-1R. DdC:(cyclo)-GGPYWP showed the most promising docking score. The results suggest that, in addition to DPP4, GLP-1R may be a hypoglycemic target of these cyclopeptides. This may bring about more discussion of plant cyclopeptides as GLP-1RAs. Moreover, peptides derived from the HB precursor (IFGGLPPP), including IFGGWPPP, IFPGWPPP, IFGGYWPPP, and IFGYGWPPPP, exhibited diverse interactions with GLP-1R and displayed backbones available for further research.

Association Between DPP-4 Inhibitors and Events of Colorectal and Liver Cancers in Patients With Diabetes Receiving Second-Line Agents: A Nested Case-Control Study

Objective

Plasma dipeptidyl peptidase-4 (DPP4) levels were significantly lower in patients with colorectal and liver cancers, and animal studies also showed DPP4 inhibitors (DPP4is) have procarcinogenic effects in colorectal cancer. Until now, whether DPP4is therapy affects the progression of liver cancer and colorectal cancer in patients with T2DM has not been well investigated. We investigated the association between cumulative defined daily dose (cDDD) of DPP4is exposure and risks of liver and colorectal cancers in patients with type 2 diabetes.

Materials and Methods

We identified 268,520 patients with diabetes receiving DPP4is as second-line agents between March 1, 2009, and December 31, 2013, from Taiwan’s National Health Insurance Research Database, Taiwan Cancer Registry, and National Death Registry of Taiwan. The amount of DPP4is were divided into three groups (low, medium, and high) based on the interquartile range of the cDDD of the DPP4is.

Results

The data showed that the low cDDD of DPP-4is was associated with a reducing risk of colorectal cancer [adjusted odds ratio (OR), 0.49; 95% CI, 0.32–0.75; P=0.001]. However, the high cDDD of DPP-4is was associated with an increasing risk of colorectal cancer (adjusted OR, 1.86; 95% CI, 1.32–2.61; P&lt;0.001). No association between DPP4is use and liver cancer risk was observed.

Conclusions

This nested case study revealed a J-shaped association between the cDDD of DPP-4is and colorectal cancer risk, but not liver cancer risk. Therefore, the effects of long-term DPP4is use on colorectal cancer risk warrant further study.

The Potential Role of Cyclopeptides from Pseudostellaria heterophylla, Linum usitatissimum and Drymaria diandra, and Peptides Derived from Heterophyllin B as Dipeptidyl Peptidase IV Inhibitors for the Treatment of Type 2 Diabetes: An In Silico Study

Dipeptidyl peptidase 4 (DPP4) inhibitors can treat type 2 diabetes by slowing GLP-1 degradation to increase insulin secretion. Studies have reported that Pseudostellaria heterophylla, Linum usita-tissimum (flaxseed), and Drymaria diandra, plants rich in Caryophyllaceae-type cyclopeptides and commonly used as herbal or dietary supplements, are effective in controlling blood sugar. The active site of DPP4 is in a cavity large enough to accommodate their cyclopeptides. Molecular modeling by AutoDock Vina reveals that certain cyclopeptides in these plants have the potential for DPP4 inhibition. In particular, “Heterophyllin B” from P. heterophylla, “Cyclolinopeptide C” from flaxseed, and “Diandrine C” from D. diandra, with binding affinities of −10.4, −10.0, and −10.7 kcal/mol, are promising. Docking suggests that DPP4 inhibition may be one of the reasons why these three plants are beneficial for lowering blood sugar. Because many protein hydrolysates have shown the effect of DPP4 inhibition, a series of peptides derived from Heterophyllin B precursor “IFGGLPPP” were included in the study. It was observed that IFWPPP (−10.5 kcal/mol), IFGGWPPP (−11.4 kcal/mol), and IFGWPPP (−12.0 kcal/mol) showed good binding affinity and interaction for DPP4. Various IFGGLPPP derivatives have the potential to serve as scaffolds for the design of novel DPP4 inhibitors.

Insulin secretory and antidiabetic actions of Heritiera fomes bark together with isolation of active phytomolecules

In folklore, Heritiera fomes (H. fomes) has been extensively used in treatment of various ailments such as diabetes, cardiac and hepatic disorders. The present study aimed to elucidate the antidiabetic actions of hot water extract of H. fomes (HWHF), including effects on insulin release from BRIN BD11 cells and isolated mouse islets as well as glucose homeostasis in high-fat-fed rats. Molecular mechanisms underlying anti-diabetic activity along with isolation of active compounds were also evaluated. Non-toxic concentrations of HWHF stimulated concentration-dependent insulin release from isolated mouse islets and clonal pancreatic β-cells. The stimulatory effect was potentiated by glucose and isobutyl methylxanthine (IBMX), persisted in presence of tolbutamide or a depolarizing concentration of KCl but was attenuated by established inhibitors of insulin release such as diazoxide, verapamil, and Ca2+ chelation. HWHF caused depolarization of the β-cell membrane and increased intracellular Ca2+. The extract also enhanced glucose uptake and insulin action in 3T3-L1 differentiated adipocytes cells and significantly inhibited in a dose-dependent manner starch digestion, protein glycation, DPP-IV enzyme activity, and glucose diffusion in vitro. Oral administration of HWHF (250 mg/5ml/kg b.w.) to high-fat fed rats significantly improved glucose tolerance and plasma insulin responses and it inhibited plasma DPP-IV activity. HWHF also decreased in vivo glucose absorption and intestinal disaccharidase activity while increasing gastrointestinal motility and unabsorbed sucrose transit. Compounds were isolated from HWHF with similar molecular weights to quercitrin (C21 H20 O11) ranging from 447.9 to 449.9 Da which stimulated the insulin release in vitro and improved both glucose tolerance and plasma insulin responses in mice. In conclusion, H. fomes and its water-soluble phytochemicals such as quercitrin may exert antidiabetic actions mediated through a variety of mechanisms which might be useful as dietary adjunct in the management of type 2 diabetes.

In vitro and in vivo antihyperglycemic activity of the ethanol extract of Heritiera fomes bark and characterization of pharmacologically active phytomolecules

OBJECTIVE

This study aimed to demonstrate the mechanistic basis of Heritiera fomes, which has traditionally been used to treat diabetes.

METHODS

Clonal pancreatic β-cells and primary islets were used to measure insulin release. 3T3-L1 cells were used to analyse insulin action, and in vitro systems were used to measure further glucose-lowering activity. In vivo assessment was performed on streptozotocin (STZ)-induced type-2 diabetic rats and reversed-phase-HPLC followed by liquid chromatography mass spectrometry (LC-MS) to detect bioactive molecules.

KEY FINDINGS

Ethanol extract of Heritiera fomes (EEHF) significantly increased insulin release with stimulatory effects comparable to 1 µM glucagon-like peptide 1, which were somewhat reduced by diazoxide, verapamil and calcium-free conditions. Insulin release was stimulated by tolbutamide, isobutyl methylxanthine and KCl. EEHF induced membrane depolarization and increased intracellular Ca2+ levels. EEHF enhanced glucose uptake in 3T3L1 cells and decreased protein glycation. EEHF significantly inhibited postprandial hyperglycaemia following sucrose loading and inversely elevated unabsorbed sucrose concentration in the gut. It suppressed glucose absorption during in situ gut perfusion. Furthermore, EEHF improved glucose tolerance, plasma insulin and gut motility, and decreased plasma dipeptidyl peptidase IV activity. Procyanidins, epicatechin and proanthocyanidins were some of the identified bioactive constituents that may involve in β-cell actions.

CONCLUSIONS

This study provides some evidence to support the use of H. fomes as an antidiabetic traditional remedy.

Alpha-to-beta cell trans-differentiation for treatment of diabetes

Diabetes mellitus is a significant cause of morbidity and mortality in the United States and worldwide. According to the CDC, in 2017, ∼34.2 million of the American population had diabetes. Also, in 2017, diabetes was the seventh leading cause of death and has become the number one biomedical financial burden in the United States. Insulin replacement therapy and medications that increase insulin secretion and improve insulin sensitivity are the main therapies used to treat diabetes. Unfortunately, there is currently no radical cure for the different types of diabetes. Loss of β cell mass is the end result that leads to both type 1 and type 2 diabetes. In the past decade, there has been an increased effort to develop therapeutic strategies to replace the lost β cell mass and restore insulin secretion. α cells have recently become an attractive target for replacing the lost β cell mass, which could eventually be a potential strategy to cure diabetes. This review highlights the advantages of using α cells as a source for generating new β cells, the various investigative approaches to convert α cells into insulin-producing cells, and the future prospects and problems of this promising diabetes therapeutic strategy.

One hundred years since insulin discovery: An update on current and future perspectives for pharmacotherapy of diabetes mellitus

Diabetes mellitus was considered a fatal malady until the discovery, extraction and commercial availability of insulins. Numerous other classes of drugs ranging from sulfonylureas to sodium-glucose co-transporter-2 inhibitors were then marketed. However, with the prevalence of diabetes mellitus increasing every year, many more drugs and therapies are under investigation. This review article aimed to summarize the significant developments in the pharmacotherapy of diabetes mellitus and outline the progress made by the recent advances, 100 years since insulins were first extracted successfully. Insulin analogues and insulin delivery pumps have further improved glycaemic control in diabetes mellitus. Cardiovascular and renal outcome trials have changed the landscape of diabetology, with some of these drugs also efficacious in nondiabetics. Newer drug delivery systems are being evaluated to improve the efficacy and reduce the dosing frequency and adverse effects of antidiabetics. Some newer drugs with novel mechanisms of action targeting type 1 and type 2 diabetes have also shown promise in recent clinical trials. These drugs include dual glucose-dependent insulinotropic polypeptide and glucagon-like peptide 1-agonists, glucokinase activators, anti-CD3 monoclonal antibodies and glimins. Their efficacy needs to be evaluated in larger studies.

Effects of DPP4 Inhibitors on Renal Outcomes in Diabetes Mellitus: A Systematic Review and Meta-Analysis

OBJECTIVES

This meta-analysis of randomized clinical trials (RCT) intends to evaluate the efficacy of DPP4 Inhibitors (DPP4I) compared with placebo, other antidiabetics (or DPP4I) on renal outcomes, adverse events (AEs), and all-cause mortality.

METHODS

We searched relevant scientific database for RCTs with DPP4I and prespecified renal end point. The effect size (mean difference or risk ratio) was reported with its 95% confidence interval.

RESULTS

Eight RCTs (n = 39040 participants) were included in the analysis. The rate of change in eGFR was not different in DPP4 inhibitor and control group. DPP4I use beyond 52 weeks did not worsen albuminuria progression (RR 0.88; 95% CI 0.80 to 0.96; high quality evidence) compared to placebo. The risk of AEs within 52 weeks (RR 0.93; 95% CI 0.80 to 1.08; moderate quality evidence), beyond 52 weeks (RR 0.98; 95% CI 0.97 to 1.00; low quality evidence), and all-cause mortality (RR 1.04; 95% CI 0.96 to 1.12; very low quality evidence) were similar to placebo. In head-to-head comparison between two DPP4I studies, no significant differences were found between alogliptin and vildagliptin for improvement in eGFR, UACR, or AE at 24 weeks.

CONCLUSIONS

DPP4I do not seem to provide persuasive benefit in the renal outcomes or all-cause mortality in diabetes mellitus, though there was no evidence for increased AEs.

Challenge of diabetes mellitus and researchers’ contributions to its control

The aim of this review study was to assess the past significant events on diabetes mellitus, transformations that took place over the years in the medical records of treatment, countries involved, and the researchers who brought about the revolutions. This study used the content analysis to report the existence of diabetes mellitus and the treatments provided by researchers to control it. The focus was mainly on three main types of diabetes (type 1, type 2, and type 3 diabetes). Ethical consideration has also helped to boost diabetic studies globally. The research has a history path from pharmaceuticals of organic-based drugs to metal-based drugs with their nanoparticles in addition to the impacts of nanomedicine, biosensors, and telemedicine. Ongoing and future studies in alternative medicine such as vanadium nanoparticles (metal nanoparticles) are promising.

Assessing Scientific Soundness and Translational Value of Animal Studies on DPP4 Inhibitors for Treating Type 2 Diabetes Mellitus

Although there is a wide range of animal models of type 2 diabetes mellitus (T2DM) used in research; we have limited evidence on their translation value. This paper provides a) a comparison of preclinical animal and clinical results on the effect of five dipeptidyl peptidase-4 (DPP4) inhibitors by comparing the pharmaceutical caused glucose changes, and b) an evaluation of methodological and reporting standards in T2DM preclinical animal studies. DPP4 inhibitors play an important role in the clinical management of T2DM: if metformin alone is not sufficient enough to control the blood sugar levels, DPP4 inhibitors are often used as second-line therapy; additionally, DPP-4 inhibitors are also used in triple therapies with metformin and sodium-glucose co-transporter-2 (SGLT-2) inhibitors or with metformin and insulin. In our analysis of 124 preclinical studies and 47 clinical trials, (1) we found no evidence of species differences in glucose change response to DPP4 inhibitors, which may suggest that, for this drug class, studies in mice and rats may be equally predictive of how well a drug will work in humans; and (2) there is good reporting of group size, sex, age, euthanasia method and self-reported compliance with animal welfare regulations in animal studies but poor reporting of justification of group size, along with a strong bias towards the use of male animals and young animals. Instead of the common non-transparent model selection, we call for a reflective and evidenced-based assessment of predictive validity of the animal models currently available.

Diabetes and Its Complications: Therapies Available, Anticipated and Aspired

Worldwide, diabetes ranks among the ten leading causes of mortality. Prevalence of diabetes is growing rapidly in low and middle income countries. It is a progressive disease leading to serious co-morbidities, which results in increased cost of treatment and over-all health system of the country. Pathophysiological alterations in Type 2 Diabetes (T2D) progressed from a simple disturbance in the functioning of the pancreas to triumvirate to ominous octet to egregious eleven to dirty dozen model. Due to complex interplay of multiple hormones in T2D, there may be multifaceted approach in its management. The 'long-term secondary complications' in uncontrolled diabetes may affect almost every organ of the body, and finally may lead to multi-organ dysfunction. Available therapies are inconsistent in maintaining long term glycemic control and their long term use may be associated with adverse effects. There is need for newer drugs, not only for glycemic control but also for prevention or mitigation of secondary microvascular and macrovascular complications. Increased knowledge of the pathophysiology of diabetes has contributed to the development of novel treatments. Several new agents like Glucagon Like Peptide - 1 (GLP-1) agonists, Dipeptidyl Peptidase IV (DPP-4) inhibitors, amylin analogues, Sodium-Glucose transport -2 (SGLT- 2) inhibitors and dual Peroxisome Proliferator-Activated Receptor (PPAR) agonists are available or will be available soon, thus extending the range of therapy for T2D, thereby preventing its long term complications. The article discusses the pathophysiology of diabetes along with its comorbidities, with a focus on existing and novel upcoming antidiabetic drugs which are under investigation. It also dives deep to deliberate upon the novel therapies that are in various stages of development. Adding new options with new mechanisms of action to the treatment armamentarium of diabetes may eventually help improve outcomes and reduce its economic burden.

New Bioactive Peptides Identified from a Tilapia Byproduct Hydrolysate Exerting Effects on DPP-IV Activity and Intestinal Hormones Regulation after Canine Gastrointestinal Simulated Digestion

Like their owners, dogs and cats are more and more affected by overweight and obesity-related problems and interest in functional pet foods is growing sharply. Through numerous studies, fish protein hydrolysates have proved their worth to prevent and manage obesity-related comorbidities like diabetes. In this work, a human in vitro static simulated gastrointestinal digestion model was adapted to the dog which allowed us to demonstrate the promising effects of a tilapia byproduct hydrolysate on the regulation of food intake and glucose metabolism. Promising effects on intestinal hormones secretion and dipeptidyl peptidase IV (DPP-IV) inhibitory activity were evidenced. We identify new bioactive peptides able to stimulate cholecystokinin (CCK) and glucagon-like peptide 1 (GLP-1) secretions, and to inhibit the DPP-IV activity after a transport study through a Caco-2 cell monolayer.

Stability-indicating ultra performance liquid chromatography method development and validation for simultaneous estimation of metformin, linagliptin, and empagliflozin in bulk and pharmaceutical dosage form

A rapid stability-indicating reversed phase-ultrapure liquid chromatography (RP-UPLC) was developed and validated for the estimation of metformin (MET), linagliptin (LIN), and empagliflozin (EMP) combination in bulk and tablet dosage form using Kromasil C₁₈ column (2.1 × 50 mm, 1.8 μm) as a stationary phase and a mixture solution of 40% phosphate buffer (pH = 3) and 60% acetonitrile as mobile phase at a flow rate of 0.6 mL/min. The detection was performed at 248 nm using a photodiode array detector. The linearity, sensitivity, selectivity, robustness, specificity, precision, and accuracy were determined. The peak area response-concentration curve was rectilinear over the range of 50-150 (MET), 5-15 (LIN), and 10-30 μg/mL (EMP) with quantitation limits of 0.042 (MET), 0.023 (LIN), and 0.059 μg/mL (EMP). The proposed method was successfully validated for the determination of MET, LIN, and EMP simultaneously in combined tablet dosage form. The performance of the proposed method was compared with reported RP-UPLC methods and found to be rapid and economical. The developed and validated stability-indicating RP-UPLC method was appropriate for the quality control and drug analysis.

Hemodynamic effects of the dipeptidyl peptidase-4 inhibitor linagliptin with renin-angiotensin system inhibitors in type 2 diabetic patients with albuminuria

Objective:

Concomitant treatment with angiotensin-converting enzyme (ACE) inhibitors and dipeptidyl peptidase-4 (DPP-4) inhibitors is increasingly common. Pharmacological studies have suggested a potential adverse drug interaction between ACE inhibitors and DPP-4 inhibitors resulting in unfavorable hemodynamic changes; very few studies have examined such an interaction between angiotensin II receptor blockers (ARBs) and DPP-4 inhibitors. We investigated blood pressure (BP) and heart rate (HR) during treatment with the DPP-4 inhibitor linagliptin in individuals receiving either ACE inhibitors or ARBs in the MARLINA-T2D trial.

Methods:

In this study, 360 individuals with type 2 diabetes and albuminuria receiving unchanged doses of ACE inhibitors or ARBs were randomized to linagliptin or placebo. Twenty-four-hour ambulatory BP monitoring, an exploratory endpoint, was conducted at baseline and after 24 weeks.

Results:

Ambulatory BP monitoring data were available for 208 individuals (linagliptin: n = 111; placebo: n = 97). Baseline mean ± SD 24-h SBP and DBP were 132.5 ± 12.4 mmHg and 75.9 ± 9.4 mmHg, respectively; mean 24-h HR was 76.3 ± 10.1 bpm. At week 24, no overall effect of the DPP-4 inhibitor versus placebo was seen on mean 24-h SBP, DBP, or HR. Furthermore, in the subgroups receiving either an ACE inhibitor or an ARB, no effect on these hemodynamic parameters was seen as a result of concomitant DPP-4 inhibitor treatment.

Conclusion:

Adding linagliptin to treatment with ACE inhibitors or ARBs was not associated with any hemodynamic changes, supporting their concomitant use in individuals with type 2 diabetes and albuminuria.

Effects of Spirulina platensis on insulin secretion, dipeptidyl peptidase IV activity and both carbohydrate digestion and absorption indicate potential as an adjunctive therapy for diabetes

Spirulina platensis has been found to be useful in the treatment of type 2 diabetes. The present study aims to elucidate the effects of ethanol extract and butanol fraction of S. platensis on insulin release and glucose homoeostasis in type 2 diabetic rats, together with their mechanism of actions. In vitro and in vivo methods were used including cellular studies to determine potential role of ion channels and cAMP in the insulinotropic actions of the extracts. The ethanol extract and butanol fraction stimulated insulin release from mouse islets and pancreatic β-cells in a concentration-dependent manner. The butanol fraction also similarly stimulated insulin release from perfused rat pancreas. The insulin-releasing action was augmented by glucose, isobutylmethylxanthine, tolbutamide and a depolarising concentration of KCl. The insulin secretory effect was attenuated with diazoxide and verapamil and by omission of extracellular Ca2+. Butanol fraction was found to significantly inhibit dipeptidyl peptidase IV enzyme activity. Moreover, butanol fraction improved glucose tolerance following oral glucose administration (2·5 g/kg body weight (b.w.)). The butanol fraction was tested on 24 h starved rats given an oral sucrose load (2·5 g/kg b.w.) to examine possible effects on carbohydrate digestion and absorption. S. platensis substantially decreased postprandial hyperglycaemia after oral sucrose load and increased unabsorbed sucrose content throughout the gut. During in situ intestinal perfusion with glucose, the butanol fraction reduced glucose absorption and promoted gut motility. Finally, chronic oral administration of butanol fraction for 28 d significantly decreased blood glucose, increased plasma insulin, pancreatic insulin stores, liver glycogen and improved lipid profile. The characterisation of active compounds from butanol fraction revealed the presence of p-coumaric acid, β-carotene, catechin and other antioxidant polyphenols. In conclusion, S. platensis could be an adjunctive therapy for the management of type 2 diabetes.

Anti-hyperglycaemic activity of H. rosa-sinensis leaves is partly mediated by inhibition of carbohydrate digestion and absorption, and enhancement of insulin secretion

ETHNOPHARMACOLOGICAL RELEVANCE

Hibiscus rosa-sinensis (HRS) is a tropical flowery plant, widely distributed in Asian region and an important traditional medicine used in many diseases including cough, diarrhoea and diabetes.

AIM OF THIS STUDY

Hibiscus rosa-sinensis (HRS) leaves have been reported to possess anti-hyperglycaemic activity, but little is known concerning the underlying mechanism. This study investigated effects of ethanol extract of HRS on insulin release and glucose homeostasis in a type 2 diabetic rat model.

MATERIALS & METHODS

Effects of ethanol extract of grinded H. rosa-sinensis (HRS) leaves on insulin release, membrane potential and intracellular calcium were determined using rat clonal β-cells (BRIN-BD11 cells) and isolated mouse pancreatic islets. Effects on DPP-IV enzyme activity were investigated in vitro. Acute effects of HRS on glucose tolerance, gut perfusion in situ, sucrose content, intestinal disaccharidase activity and gut motility were measured. Streptozotocin induced type 2 diabetic rats treated for 28 days with ethanol extract of HRS leaf (250 and 500 mg/kg) were used to assess glucose homeostasis.

RESULTS

HRS, significantly increased insulin release from clonal rat BRIN-BD11 cells and this action was confirmed using isolated mouse pancreas islets with stimulatory effects equivalent to GLP-1. HRS induced membrane depolarization and increased intracellular Ca²⁺ in BRIN BD11 cells and significantly inhibited DPP-IV enzyme activity in vitro. HRS administration in vivo improved glucose tolerance in type 2 diabetic rats, inhibited both glucose absorption during gut perfusion and postprandial hyperglycaemia and it reversibly increased unabsorbed sucrose passage through the gut following sucrose ingestion. HRS decreased intestinal disaccharidase activity and increased gastrointestinal motility in non-diabetic rats. In a chronic 28-day study with type 2 diabetic rats, HRS, at 250 or 500 mg/kg, significantly decreased serum glucose, cholesterol, triglycerides and increased circulating insulin, HDL cholesterol and hepatic glycogen without increasing body weight.

CONCLUSION

These data suggest the antihyperglycaemic activity of HRS is mediated by inhibiting carbohydrate digestion and absorption, while significantly enhancing insulin secretion in a dose dependent manner. This suggests that HRS has potential as a novel antidiabetic therapy or a dietary supplement for the treatment of type 2 diabetes.

A Comprehensive Review on Preclinical Diabetic Models

BACKGROUND

Preclinical experimental models historically play a critical role in the exploration and characterization of disease pathophysiology. Further, these in-vivo and in-vitro preclinical experiments help in target identification, evaluation of novel therapeutic agents and validation of treatments.

INTRODUCTION

Diabetes mellitus (DM) is a multifaceted metabolic disorder of multidimensional aetiologies with the cardinal feature of chronic hyperglycemia. To avoid or minimize late complications of diabetes and related costs, primary prevention and early treatment are therefore necessary. Due to its chronic manifestations, new treatment strategies need to be developed, because of the limited effectiveness of the current therapies.

METHODS

The study included electronic databases such as Pubmed, Web of Science and Scopus. The datasets were searched for entries of studies up to June, 2018.

RESULTS

A large number of in-vivo and in-vitro models have been presented for evaluating the mechanism of anti-hyperglycaemic effect of drugs in hormone-, chemically-, pathogen-induced animal models of diabetes mellitus. The advantages and limitations of each model have also been addressed in this review.

CONCLUSION

This review encompasses the wide pathophysiological and molecular mechanisms associated with diabetes, particularly focusing on the challenges associated with the evaluation and predictive validation of these models as ideal animal models for preclinical assessments and discovering new drugs and therapeutic agents for translational application in humans. This review may further contribute to discover a novel drug to treat diabetes more efficaciously with minimum or no side effects. Furthermore, it also highlights ongoing research and considers the future perspectives in the field of diabetes.

Durability of glycaemic control with dapagliflozin, an SGLT2 inhibitor, compared with saxagliptin, a DPP4 inhibitor, in patients with inadequately controlled type 2 diabetes

Dapagliflozin is associated with greater reductions in HbA1c and weight than saxagliptin in management of type 2 diabetes mellitus (T2DM). The present post hoc analyses compared the durability of these effects over short- and long-term follow-up in patients with T2DM who were inadequately controlled with metformin (≥1500 mg/day) and who were receiving either dapagliflozin (10 mg/day) or saxagliptin (5 mg/day). Failure of glycaemiccontrol was assessed using the slope of the change in HbA1c from baseline-over-time regression line (coefficient of failure [CoF]). CoF was compared directly (dapagliflozin vs saxagliptin) over the short term (NCT01606007, 24 weeks) and indirectly (placebo-adjusted) over the long term (NCT00528879 and NCT00121667, 102 weeks). A low CoF value indicated greater durability. CoF was lower for dapagliflozin versus saxagliptin over 18-24 weeks (-1.38%/year; 95% CI, -2.41 to -0.35; P = .009) and 20-102 weeks (-0.37%/year; 95% CI, -0.73 to -0.02; P = .04). Fewer dapagliflozin-treated patients versus saxagliptin-treated patients required rescue medication or discontinued the study because of failure to achieve glycaemic control at 24 weeks (3.4% vs 9.4%; P = .0191). In patients with T2DM who were inadequately controlled with metformin, dapagliflozin was associated with greater durability of glycaemic control than saxagliptin over 18-24 and 20-102 weeks.

The dipeptidyl peptidase 4 inhibitor sitagliptin improves oxidative stress and ameliorates glomerular lesions in a rat model of type 1 diabetes

AIMS

Oxidative stress has been linked to the development and progression of diabetic nephropathy (DN). The present study evaluated whether the dipeptidyl peptidase-4 inhibitor sitagliptin attenuates glomerular lesions and oxidative stress evoked by chronic hyperglycemia, by a mechanism independent of insulin secretion and glycemia normalization.

MAIN METHODS

A rat model of DN caused by streptozotocin injection was established and the effects of sitagliptin (5 mg/kg/day) were evaluated after two weeks of treatment.

KEY FINDINGS

Sitagliptin treatment did not change body weight, glycemic and lipid profiles. However, histopathological observation revealed that sitagliptin attenuates diabetes-induced glomerular lesions on diabetic rats. Sitagliptin also ameliorated the increase in DPP-4 content and promoted the stabilization of GLP-1 in the diabetic kidney. Furthermore, sitagliptin treatment significantly attenuated the increase of free-radical formation and the decrease of antioxidant defenses, attenuating therefore the oxidative stress in the kidneys of diabetic animals.

SIGNIFICANCE

The results suggest that sitagliptin treatment alleviates kidney oxidative stress in type 1 diabetic rats, which could play a key role in reducing the progression of DN.

Therapeutic Options Targeting Oxidative Stress, Mitochondrial Dysfunction and Inflammation to Hinder the Progression of Vascular Complications of Diabetes

Type 2 diabetes mellitus is a leading cause of morbidity and mortality worldwide, given its serious associated complications. Despite constant efforts and intensive research, an effective, ubiquitous treatment still eludes the scientific community. As such, the identification of novel avenues of research is key to the potential discovery of this evasive "silver bullet." We focus on this review on the matter of diabetic injury to endothelial tissue and some of the pivotal underlying mechanisms, including hyperglycemia and hyperlipidemia evoked oxidative stress and inflammation. In this sense, we revisited the most promising therapeutic interventions (both non-pharmacological and antidiabetic drugs) targeting oxidative stress and inflammation to hinder progression of vascular complications of diabetes. This review article gives particular attention to the relevance of mitochondrial function, an often ignored and understudied organelle in the vascular endothelium. We highlight the importance of mitochondrial function and number homeostasis in diabetic conditions and discuss the work conducted to address the aforementioned issue by the use of various therapeutic strategies. We explore here the functional, biochemical and bioenergetic alterations provoked by hyperglycemia in the endothelium, from elevated oxidative stress to inflammation and cell death, as well as loss of tissue function. Furthermore, we synthetize the literature regarding the current and promising approaches into dealing with these alterations. We discuss how known agents and therapeutic behaviors (as, for example, metformin, dietary restriction or antioxidants) can restore normality to mitochondrial and endothelial function, preserving the tissue's function and averting the aforementioned complications.

Characterization of the Open-Label Lead-In Period of Two Randomized Controlled Phase 3 Trials Evaluating Dapagliflozin, Saxagliptin, and Metformin in Type 2 Diabetes

INTRODUCTION

To examine the utility of sequential versus dual add-on approaches in patients who have type 2 diabetes and inadequate glycemic control with metformin therapy alone, we characterized the efficacy and safety of dual therapy with dapagliflozin or saxagliptin added to metformin in the open-label lead-in periods of two phase 3 trials (study 1, NCT01619059; study 2, NCT01646320) that evaluated triple therapy in patients with inadequately controlled type 2 diabetes.

METHODS

During the lead-in periods of each trial, patients [glycated hemoglobin (HbA1c) 8.0-11.5%] who had been receiving metformin ≥ 1500 mg/day for ≥ 8 weeks received metformin immediate release at an equivalent dose plus dapagliflozin 10 mg/day (study 1; N = 482) or saxagliptin 5 mg/day (study 2; N = 349) for 16 weeks. Efficacy end points were assessed at week - 2 before randomization.

RESULTS

Mean change in HbA1c [95% confidence interval (CI)] from lead-in baseline (study 1, 9.3%; study 2, 9.4%) was - 1.6% (- 1.7, - 1.5) in study 1 and - 1.3% (- 1.5, - 1.2) in study 2. Mean changes (95% CI) from lead-in baseline in weight and fasting plasma glucose were - 2.4 kg (- 2.6, - 2.1) and - 47.5 mg/dL (- 52.8, - 42.3) for study 1 and - 0.5 kg (- 0.8, - 0.2) and - 28.5 mg/dL (- 35.8, - 21.2) for study 2. At the end of the lead-in period, 22.0% of patients achieved HbA1c < 7.0% in study 1 and 17.5% in study 2. Dual therapy was well tolerated, with hypoglycemia incidence < 1% in both studies.

CONCLUSION

Dual therapy improved glycemic control and was well tolerated; however, most patients required additional therapy to further improve HbA1c towards target, suggesting that an early move to triple therapy with oral glucose-lowering drugs rather than a stepwise approach may be beneficial for patients with high HbA1c levels on metformin therapy.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01619059, NCT01646320.

FUNDING

AstraZeneca.

Naringin enhances reverse cholesterol transport in high fat/low streptozocin induced diabetic rats

Naringin, a citrus-derived flavonoid with antihyperglycemic, antihyperlipidemic, and antioxidant properties, is reported to be a useful nutraceutical in the management of diabetes and its complications. This study investigated the mechanism of antiatherogenic properties of naringin in type 2 diabetes (T2DM) using high fat-low streptozocin rat model of T2DM. Rats were treated daily with 50, 100 and 200 mg/kg naringin orally for 21days. Levels of biomarkers of T2DM, lipid profile and activity of paraoxonase (PON) were assayed spectrophotometrically. The levels of expression of hepatic 3-hydroxy-3-methyl-glutaryl-CoA reductase (Hmgcr), scavenger receptor class B member 1 (Scarb1), aryl hydrocarbon receptor (Ahr), hepatic Lipase (Lipc), and lecithin-cholesterol acyltransferase (Lcat) were assessed using relative reverse transcriptase polymerase chain reaction technique. Naringin treatment resulted in a dose-dependent significant (p < 0.05) decrease in the levels of plasma cholesterol and triglyceride from 84.84 ± 1.62 to 55.59 ± 1.50 mg/dL and 123.03 ± 15.11 to 55.00 ± 0.86 mg/dL, respectively, at 200 mg/kg naringin. In the liver, Scarb1 and Ahr were significantly (p < 0.05) upregulated at 200 mg/kg naringin while Lipc and Lcat were significantly (p < 0.05) upregulated by 50 mg/kg naringin. T2DM-induced decrease in PON activities in the plasma, liver and HDL was significantly (p < 0.05) reversed by 200 mg/kg naringin treatment. These genes play critical roles in reverse cholesterol transport and hence our results showed that the antiatherogenic property of naringin in T2DM involves enhancement of reverse cholesterol transport and PON activity.

Peptides Derived from Foods as Supportive Diet Components in the Prevention of Metabolic Syndrome

Metabolic syndrome (MSyn) includes physiological, biochemical, clinical, and metabolic abnormalities, leading to an increase in health problems like obesity, dyslipidemia, cardiovascular diseases, and diabetes, which contribute to an increase in mortality rate. One of the main factors having a key impact on our health is the food we consume. Thus, scientists work towards the discovery of novel bioactive compounds with therapeutic potential to address MSyn. According to scientific reports, peptides derived from food proteins exhibit bioactivities important for the prevention of MSyn diseases; that is, they regulate blood pressure and glycemia; reduce cholesterol level and body mass; and scavenge free radicals. The aim of this review is to study the potential role of peptides in the prevention of MSyn. Particularly peptides which exhibit the following activities: antihypertensive [angiotensin-converting enzyme (ACE) inhibition (EC 3.4.15.1)], antidiabetic [dipeptidyl peptidase IV (DPP-IV) (EC 3.4.14.5)/α-glucosidase (EC 3.2.1.20)/α-amylase (EC 3.2.1.1) inhibition)], cholesterol level reduction, antioxidative, and obesity prevention, were studied. If possible, special attention is paid in the review to the bioactivities of peptides that were measured in vivo. Some examples of peptides showing dual or multiple action against MSyn targets are presented. Moreover, using the database of bioactive peptide sequences (BIOPEP) we made a list of peptides serving simultaneous functions in counteracting MSyn dysfunctions. Such an approach may simplify the discovery of MSyn preventive peptides, as well as highlight some of them as potent bioactive ingredients that may be incorporated into foods. Moreover, the research strategy involving the in silico and in vitro/in vivo methodologies may be useful in the production of food protein hydrolysates supporting the treatment of MSyn dysfunctions.

Minimizing Glycemic Fluctuations in Patients with Type 2 Diabetes: Approaches and Importance

Glycemic fluctuations, characterized by short-term oscillations in plasma glucose, are important when managing type 2 diabetes (T2D) and may be considered a target of glucose-lowering therapies. Continuous glucose monitoring (CGM) has been used to evaluate the effects of different treatments on glycemic fluctuations. This review examines approaches to and the importance of minimizing glycemic fluctuations among patients with T2D. Measures of HbA_1c, fructosamine, and glycated albumin reflect a long-term average of plasma glucose, and are therefore unable to provide an accurate measure of short-term glycemic oscillations. CGM provides accurate monitoring of real-time glucose fluctuations and has been used to investigate the effects of lifestyle and treatment on daily glycemic control. Dipeptidyl peptidase-4 inhibitors, sodium-glucose cotransporter 2 inhibitors, and glucagon-like peptide-1 receptor agonists have demonstrated significant improvements in measures such as the mean amplitude of glucose excursions and standard deviation of CGM. Case studies of two patients with T2D utilizing CGM are also included in this review, which demonstrated that CGM was a useful tool for diagnosing unrecognized hypoglycemia and hyperglycemia in situations in which it was impractical to check fingerstick concentrations. Altogether, the evidence suggests that glycemic fluctuations are a potential target to consider when managing T2D. CGM allows for the real-time evaluation of glycemic fluctuations and may assist in the development of an individualized treatment plan to adequately control short-term oscillations in blood glucose levels.

Renoprotective Effects of the Dipeptidyl Peptidase-4 Inhibitor Sitagliptin: A Review in Type 2 Diabetes

Diabetic nephropathy (DN) is now the single commonest cause of end-stage renal disease (ESRD) worldwide and one of the main causes of death in diabetic patients. It is also acknowledged as an independent risk factor for cardiovascular disease (CVD). Since sitagliptin was approved, many studies have been carried out revealing its ability to not only improve metabolic control but also ameliorate dysfunction in various diabetes-targeted organs, especially the kidney, due to putative underlying cytoprotective properties, namely, its antiapoptotic, antioxidant, anti-inflammatory, and antifibrotic properties. Despite overall recommendations, many patients spend a long time well outside the recommended glycaemic range and, therefore, have an increased risk for developing micro- and macrovascular complications. Currently, it is becoming clearer that type 2 diabetes mellitus (T2DM) management must envision not only the improvement in glycaemic control but also, and particularly, the prevention of pancreatic deterioration and the evolution of complications, such as DN. This review aims to provide an overview of the current knowledge in the field of renoprotective actions of sitagliptin, namely, improvement in diabetic dysmetabolism, hemodynamic factors, renal function, diabetic kidney lesions, and cytoprotective properties.

A randomised, active- and placebo-controlled, three-period crossover trial to investigate short-term effects of the dipeptidyl peptidase-4 inhibitor linagliptin on macro- and microvascular endothelial function in type 2 diabetes

Background

Studies of dipeptidyl peptidase (DPP)-4 inhibitors report heterogeneous effects on endothelial function in patients with type 2 diabetes (T2D). This study assessed the effects of the DPP-4 inhibitor linagliptin versus the sulphonylurea glimepiride and placebo on measures of macro- and microvascular endothelial function in patients with T2D who represented a primary cardiovascular disease prevention population.

Methods

This crossover study randomised T2D patients (n = 42) with glycated haemoglobin (HbA1c) ≤7.5%, no diagnosed macro- or microvascular disease and on stable metformin background to linagliptin 5 mg qd, glimepiride 1–4 mg qd or placebo for 28 days. Fasting and postprandial macrovascular endothelial function, measured using brachial flow-mediated vasodilation, and microvascular function, measured using laser-Doppler on the dorsal thenar site of the right hand, were analysed after 28 days.

Results

Baseline mean (standard deviation) age, body mass index and HbA1c were 60.3 (6.0) years, 30.3 (3.0) kg/m² and 7.41 (0.61)%, respectively. After 28 days, changes in fasting flow-mediated vasodilation were similar between the three study arms (treatment ratio, gMean [90% confidence interval]: linagliptin vs glimepiride, 0.884 [0.633–1.235]; linagliptin vs placebo, 0.884 [0.632–1.235]; glimepiride vs placebo, 1.000 [0.715–1.397]; P = not significant for all comparisons). Similarly, no differences were seen in postprandial flow-mediated vasodilation. However, under fasting conditions, linagliptin significantly improved microvascular function as shown by a 34% increase in hyperaemia area (P = 0.045 vs glimepiride), a 34% increase in resting blow flow (P = 0.011 vs glimepiride, P = 0.003 vs placebo), and a 25% increase in peak blood flow (P = 0.009 vs glimepiride, P = 0.003 vs placebo). There were no significant differences between treatments in postprandial changes. Linagliptin had no effect on heart rate or blood pressure. Rates of overall adverse events with linagliptin, glimepiride and placebo were 27.5, 61.0 and 35.0%, respectively. Fewer hypoglycaemic events were seen with linagliptin (5.0%) and placebo (2.5%) than with glimepiride (39.0%).

Conclusions

Linagliptin had no effect on macrovascular function in T2D, but significantly improved microvascular function in the fasting state.

Trial registration ClinicalTrials.gov identifier—NCT01703286; registered October 1, 2012

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-016-0493-3) contains supplementary material, which is available to authorized users.

Using Caco-2 cells as novel identification tool for food-derived DPP-IV inhibitors

Dietary proteins have recently been investigated as a new source of DPP-IV inhibitory peptides with limited side effects and promising applications. Numerous studies have highlighted and identified peptide sequences able to inhibit DPP-IV activity in vitro, mostly from milk proteins. However, the correlation to in vivo studies remains scarce because standard in vitro assays with purified enzyme do not accurately simulate key factors impacting peptide bioactivity such as intestinal and brush border enzymes or cellular permeability. Therefore, a DPP-IV activity inhibition assay is here proposed using non differentiated confluent Caco-2 cells to rapidly assess food-derived peptide inhibitory potential in approaching intestinal conditions. DPP-IV gene expression was first checked and specific DPP-IV substrate was used to implement the assay. Using a specific DPP-IV inhibitor confirmed that non differentiated Caco-2 cells express measurable DPPIV activity. This in situ assay was then applied to digests which already demonstrated a DPP-IV inhibitory potential with a standard assay using purified enzyme. Bovine hemoglobin and cuttlefish hydrolysate digests from simulated gastrointestinal digestion exerted a dose response inhibition on DPP-IV activity but displayed different inhibitory potentials.

Protein Digestion-Derived Peptides and the Peripheral Regulation of Food Intake

The gut plays a central role in energy homeostasis. Food intake regulation strongly relies on the gut-brain axis, and numerous studies have pointed out the significant role played by gut hormones released from enteroendocrine cells. It is well known that digestive products of dietary protein possess a high satiating effect compared to carbohydrates and fat. Nevertheless, the processes occurring in the gut during protein digestion involved in the short-term regulation of food intake are still not totally unraveled. This review provides a concise overview of the current data concerning the implication of food-derived peptides in the peripheral regulation of food intake with a focus on the gut hormones cholecystokinin and glucagon-like peptide 1 regulation and the relationship with some aspects of glucose homeostasis.