Differential chemistry (structure), mechanism of action, and pharmacology of GLP-1 receptor agonists and DPP-4 inhibitors

Effects of newer-generation anti-diabetics on diabetic retinopathy: a critical review

Diabetic retinopathy (DR) is the leading etiology of blindness in the working population of the USA. Its long-term management relies on effective glycemic control. Seven anti-diabetic classes have been introduced for patients with type 2 diabetes (T2D) in the past two decades, with different glucose-lowering and cardiovascular benefits. Yet, their effects specifically on DR have not been studied in detail. A systematic review of the literature was conducted to investigate this topic, focusing on the available clinical data for T2D. Published studies were evaluated based on their level of statistical evidence, as long as they incorporated at least one endpoint or adverse event pertaining to retinal health. Fifty nine articles met our inclusion criteria and were grouped per anti-diabetic class as follows: alpha-glucosidase inhibitors (1), peroxisome proliferator-activated receptor gamma (PPAR-γ) agonists (8), amylin analogs (1), glucagon-like peptide-1 (GLP-1) receptor agonists (28), dipeptidyl peptidase 4 (DPP-4) inhibitors (9), and sodium glucose co-transporter-2 (SGLT-2) inhibitors (9), plus one retrospective study and two meta-analyses evaluating more than one of the aforementioned anti-diabetic categories. We also reviewed publicly-announced results of trials for the recently-introduced class of twincretins. The available data indicates that most drugs in the newer anti-diabetic classes are neutral to DR progression; however, there are subclasses differences in specific drugs and T2D populations. In particular, there is evidence suggesting there may be worse diabetic macular edema with PPAR-gamma agonists, potential slight DR worsening with semaglutide (GLP-1 receptor agonist), and potential slight increase in the incidence of retinal vein occlusion in elderly and patients with advanced kidney disease receiving SGLT-2 inhibitors. All these warrant further investigation. Longer follow-up and systematic assessment of at least one DR-related endpoint are highly recommended for all future trials in the T2D field, to ultimately address this topic.

Insulin resistance and Metabolic dysfunction-associated steatotic liver disease (MASLD): Pathways of action of hypoglycemic agents

Metabolic dysfunction-associated steatotic liver disease (MASLD) is characterized by overweight/obesity, and the presence of type 2 diabetes mellitus is the most important criterion. We propose an independent disease perspective without exclusion criteria and with less heterogeneity and greater impact because, according to the National Health and Nutrition Survey (ENSANUT), in Mexico, 25 % of adults over 60 years of age suffer from diabetes, and 96 % of those over 50 years of age have abdominal obesity. Due to the impact of insulin resistance in the pathophysiology of MASLD, which results in damage to hepatocytes, this work aims to provide an overview of the action pathways of hypoglycemic agents such as glucagon-like-1 receptor agonist and peroxisome proliferator-activated receptor-gamma agonists, whose importance lies in the fact that they are currently undergoing phase 2 studies, as well as dipeptidyl peptidase 4 inhibitors and sodium-glucose co-transporter type 2 inhibitors, which are undergoing phase 1 study trials.

Antidiabetic Drugs in Breast Cancer Patients

Diabetes is one of the leading chronic conditions worldwide, and breast cancer is the most prevalent cancer in women worldwide. The linkage between diabetes and its ability to increase the risk of breast cancer should always be analyzed in patients. This review focuses on the impact of antihyperglycemic therapy in breast cancer patients. Patients with diabetes have a higher risk of developing cancer than the general population. Moreover, diabetes patients have a higher incidence and mortality of breast cancer. In this review, we describe the influence of antidiabetic drugs from insulin and metformin to the current and emerging therapies, incretins and SGLT-2 inhibitors, on breast cancer prognosis. We also emphasize the role of obesity and the metastasis process in breast cancer patients who are treated with antidiabetic drugs.

Single-Anastomosis Sleeve Jejunal Bypass as a Treatment for Morbid Obesity: A Systematic Review and Meta-Analysis

Single-anastomosis sleeve jejunal (SASJ) bypass is a bariatric surgery technique with promising results. However, evidence of its efficacy and safety is still lacking. This study aimed to summarize the evidence regarding the efficacy and safety of SASJ bypass surgery in the treatment of morbid obesity. The literature was searched for English-language studies published from inception till November 26, 2023, on MEDLINE/PubMed, Cochrane Library, Web of Science, ProQuest, Scopus, SCINAPSE, and Google Scholar. The search terms included "morbid obesity," "bariatric surgery," and "single anastomosis sleeve jejunal bypass." Extracted data included the body mass index (BMI) before and after surgery, percent total weight loss (%TWL), percent excess weight loss (%EWL), and improvement in preoperative comorbidities. Pooling of the data was done using random effects or fixed-effect models based on the presence of significant heterogeneity. Nine studies were included in this systematic review and meta-analysis. The change in BMI from baseline at 12 months after SASJ bypass was significant (standardized mean difference (SMD) = -3.576, 95% confidence interval (CI) = -5.423, -1.730; I² = 99.23%). At 12 months after surgery, the pooled %TWL was 42.526 (95% CI = 37.948, 47.105; I² = 97.15%), and the pooled %EWL was 75.258 (95% CI = 67.061, 83.456; I² = 99.26%). The pooled incidence of postoperative improvement in diabetes mellitus was 91% (95% CI = 79.6%, 98%, I² = 82%). The overall rate of complications was 9.9% (95% CI = 2.5%, 21.6%; I² = 92.64%). Regarding the short- and mid-term outcomes, SASJ bypass is a safe and effective procedure for weight loss in patients with morbid obesity, with an acceptable rate of complications. The procedure is also associated with a marked improvement in obesity-related comorbidities.

DPP-4 inhibitors for treating T2DM - hype or hope? an analysis based on the current literature

DPP-4 inhibition is an interesting line of therapy for treating Type 2 Diabetes Mellitus (T2DM) and is based on promoting the incretin effect. Here, the authors have presented a brief appraisal of DPP-4 inhibitors, their modes of action, and the clinical efficiency of currently available drugs based on DPP-4 inhibitors. The safety profiles as well as future directions including their potential application in improving COVID-19 patient outcomes have also been discussed in detail. This review also highlights the existing queries and evidence gaps in DPP-4 inhibitor research. Authors have concluded that the excitement surrounding DPP-4 inhibitors is justified because in addition to controlling blood glucose level, they are good at managing risk factors associated with diabetes.

New strategies to improve clinical outcomes for diabetic kidney disease

BACKGROUND

Diabetic kidney disease (DKD), the most common cause of kidney failure and end-stage kidney disease worldwide, will develop in almost half of all people with type 2 diabetes. With the incidence of type 2 diabetes continuing to increase, early detection and management of DKD is of great clinical importance.

MAIN BODY

This review provides a comprehensive clinical update for DKD in people with type 2 diabetes, with a special focus on new treatment modalities. The traditional strategies for prevention and treatment of DKD, i.e., glycemic control and blood pressure management, have only modest effects on minimizing glomerular filtration rate decline or progression to end-stage kidney disease. While cardiovascular outcome trials of SGLT-2i show a positive effect of SGLT-2i on several kidney disease-related endpoints, the effect of GLP-1 RA on kidney-disease endpoints other than reduced albuminuria remain to be established. Non-steroidal mineralocorticoid receptor antagonists also evoke cardiovascular and kidney protective effects.

CONCLUSION

With these new agents and the promise of additional agents under clinical development, clinicians will be more able to personalize treatment of DKD in patients with type 2 diabetes.

Diabetes in COVID-19 patients: challenges and possible management strategies

Background

The recent pandemic of coronavirus disease 19 (COVID-19) has been causing intense stress among the global population. In the case of hospitalized and ICU-admitted COVID-19 patients with comorbidities, it has been observed that a major portion of them are diabetic. Therefore, researchers had indicated a link between diabetes mellitus (DM) and COVID-19. Furthermore, DM is a potential risk factor for the severity of COVID-19 cases. Thus, in this study, the correlation existing between diabetic patients and COVID-19 was summarized.

Main body of the abstract

Diabetic patients have a weaker immune system, less viral clearance rate, malfunctions of metabolic activity due to their high blood glucose level, and other associated problems. This does not increase the susceptibility for the patients to be infected with COVID-19. However, the severity of COVID-19 can worsen due to the comorbidity of DM.

Short conclusion

Proper management, appropriate use of drugs that do not increase the ACE2 expression, lowering blood glucose level, decreasing the susceptibility of SARS-CoV-2, and maintaining a healthy lifestyle could be effective.

Association between cardiometabolic risk factors and COVID-19 susceptibility, severity and mortality: a review

The novel coronavirus, which began spreading from China Wuhan and gradually spreaded to most countries, led to the announcement by the World Health Organization on March 11, 2020, as a new pandemic. The most important point presented by the World Health Organization about this disease is to better understand the risk factors that exacerbate the course of the disease and worsen its prognosis. Due to the high majority of cardio metabolic risk factors like obesity, hypertension, diabetes, and dyslipidemia among the population over 60 years old and higher, these cardio metabolic risk factors along with the age of these people could worsen the prognosis of the coronavirus disease of 2019 (COVID-19) and its mortality. In this study, we aimed to review the articles from the beginning of the pandemic on the impression of cardio metabolic risk factors on COVID-19 and the effectiveness of COVID-19 on how to manage these diseases. All the factors studied in this article, including hypertension, diabetes mellitus, dyslipidemia, and obesity exacerbate the course of Covid-19 disease by different mechanisms, and the inflammatory process caused by coronavirus can also create a vicious cycle in controlling these diseases for patients.

Recent Medicinal Chemistry Approach for the Development of Dipeptidyl Peptidase IV Inhibitors

BACKGROUND

Diabetes, a metabolic disease, occurs due to a decreased or no effect of insulin on the blood glucose level. The current oral medications stimulate insulin release, increase glucose absorption and its utilization, and decrease hepatic glucose output. Two major incretin hormones like Glucose-dependent insulinotropic polypeptide (GIP) and glucagonlike peptide - 1 (GLP-1) stimulate insulin release after a meal, but their action is inhibited by enzyme dipeptidyl peptidase- IV.

OBJECTIVE

The activity of endogenous GLP-1 and GIP prolongs and extends with DPP IV inhibitors, which are responsible for the stimulation of insulin secretion and regulation of blood glucose level. DPP IV inhibitors have shown effectiveness and endurability with a neutral effect on weight as well as less chances of hypoglycemia in the management of type 2 diabetes. These journeys started from Sitagliptin (marketed in 2006) to Evogliptin (marketed in 2015, Korea).

CONCLUSION

Treatment of type 2 diabetes includes lifestyle changes, oral medications, and insulin. Newer and superior therapies are needed more than currently prescribed drugs. Various heterocyclic derivatives have been tried, but due to masking of DASH proteins, CYP enzymes, and hERG channel, they showed side effects. Based on these, the study has been focused on the development of safe, influential, selective, and long-lasting inhibitors of DPP IV.

Effects of Incretin-Related Diabetes Drugs on Bone Formation and Bone Resorption

Patients with type 2 diabetes have an increased risk of fracture compared to the general population. Glucose absorption is accelerated by incretin hormones, which induce insulin secretion from the pancreas. The level of the incretin hormone, glucagon-like peptide-1 (GLP-1), shows an immediate postprandial increase, and the circulating level of intact GLP-1 is reduced rapidly by dipeptidyl peptidase-4 (DPP-4)-mediated inactivation. Therefore, GLP-1 receptor agonists and DPP-4 inhibitors are effective in the treatment of type 2 diabetes. However, these incretin-related diabetic agents have been reported to affect bone metabolism, including bone formation and resorption. These agents enhance the expression of bone markers, and have been applied to improve bone quality and bone density. In addition, they have been reported to suppress chronic inflammation and reduce the levels of inflammatory cytokine expression. Previously, we reported that these incretin-related agents inhibited both the expression of inflammatory cytokines and inflammation-induced bone resorption. This review presents an overview of current knowledge regarding the effects of incretin-related diabetes drugs on osteoblast differentiation and bone formation as well as osteoclast differentiation and bone resorption. The mechanisms by which incretin-related diabetes drugs regulate bone formation and bone resorption are also discussed.

Safety, Pharmacokinetics, and Pharmacodynamics of a Dipeptidyl Peptidase-4 Inhibitor: A Randomized, Double-Blinded, Placebo-Controlled Daily Administration of Fotagliptin Benzoate for 14 Days for Type 2 Diabetes Mellitus

This study investigated the pharmacokinetics, pharmacodynamics, and safety of fotagliptin benzoate (fotagliptin), a dipeptidyl peptidase-4 (DPP-4) inhibitor, in Chinese patients with type 2 diabetes mellitus (T2DM). In a randomized, double-blinded, placebo-controlled study, 10 and 4 patients with T2DM were randomized and received, respectively, once-daily oral fotagliptin (24 mg) or placebo, for 14 days. The pharmacokinetics and pharmacodynamics were assessed throughout the study, including monitoring DPP-4, glucagon-like peptide-1 (GLP-1), glycosylated hemoglobin, and fasting blood glucose. Fotagliptin was rapidly absorbed, and the median time to maximum concentration value was ∼1.5 hours. Plasma fotagliptin levels were stable after 14 days of once-daily dosage. The accumulation ratios for the area under the plasma concentration-time curve of fotagliptin, M1, and M2-1, were 1.19 ± 0.10, 1.59 ± 0.27, and 1.39 ± 0.26, respectively. The durations for DPP-4 inhibition >80% in the fotagliptin group on days 1 and 14 were 23.5 and 24.0 hours, respectively. The concentrations of GLP-1 were higher on days 1 and 14 than at the baseline. No serious complications occurred. Fotagliptin showed favorable pharmacokinetics and pharmacodynamics and was well tolerated. Treatment with fotagliptin can achieve high DPP-4 inhibition and increase plasma GLP-1. A once-per-day dosing regimen may be recommended as clinically efficacious.

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

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

Understanding the interplay between food structure, intestinal bacterial fermentation and appetite control

Epidemiological and clinical evidence highlight the benefit of dietary fibre consumption on body weight. This benefit is partly attributed to the interaction of dietary fibre with the gut microbiota. Dietary fibre possesses a complex food structure which resists digestion in the upper gut and therefore reaches the distal gut where it becomes available for bacterial fermentation. This process yields SCFA which stimulate the release of appetite-suppressing hormones glucagon-like peptide-1 and peptide YY. Food structures can further enhance the delivery of fermentable substrates to the distal gut by protecting the intracellular nutrients during upper gastrointestinal digestion. Domestic and industrial processing can disturb these food structures that act like barriers towards digestive enzymes. This leads to more digestible products that are better absorbed in the upper gut. As a result, less resistant material (fibre) and intracellular nutrients may reach the distal gut, thus reducing substrates for bacterial fermentation and its subsequent benefits on the host metabolism including appetite suppression. Understanding this link is essential for the design of diets and food products that can promote appetite suppression and act as a successful strategy towards obesity management. This article reviews the current evidence in the interplay between food structure, bacterial fermentation and appetite control.

Pharmacophore- based virtual screening, 3D- QSAR, molecular docking approach for identification of potential dipeptidyl peptidase IV inhibitors

Pharmacophore modeling, molecular docking, and in silico ADME studies have been carried out to determine the binding mode and drug likeliness profile of Pyrrolidine derivatives as Dipeptidyl peptidase IV inhibitors. A five point pharmacophore model (AAADH_1) was generated using 96 compounds with IC₅₀ values ranging from 1.8 to 13000 nM. A statistically significant 3D-QSAR model was generated from the pharmacophore hypothesis. The model had a high correlation coefficient (R² - 0.92), cross validation coefficient (Q² - 0.776) and F value (F - 144) at 6 component Partial least square factor. Pearson r of 0.7124 indicated greater degree of confidence on the model. The accuracy and predictability of the generated model were checked by Enrichment factor, Receiver operating characteristic curves, area under curve, Boltzmann-enhanced discrimination of Receiver operating characteristic and the Robust initial enhancement. To identify novel and potent Dipeptidyl peptidase IV inhibitors, virtual screening was performed using the ligand and database screening. Considering the potent hit molecules on the basis of pharmacophore virtual screening, we have designed new molecules and further subjected to see the interaction with protein. The catalytic domain of Dipeptidyl peptidase IV enzyme in complex with Vildagliptin (PDB Code: 6B1E) was obtained from protein data bank with resolution 1.77 A°. Compound 75 showed the better binding (dock score -7.966) with protein than standard drug vildagliptin (Dock Score -6.554). The hits obtained on virtual screening of the database have provided new chemical starting points for design and development of novel Dipeptidyl peptidase IV inhibitory agents.Communicated by Ramaswamy H. Sarma.

Single-Anastomosis Sleeve Jejunal Bypass, a Novel Bariatric Surgery, Versus Other Familiar Methods: Results of a 6-Month Follow-up-a Comparative Study

BACKGROUND

Obesity and its associated morbidities have become a significant concern all over the world. Bariatric surgery, regardless of its type, is the most effective approach for treating morbid obesity. Single-anastomosis sleeve jejunal (SASJ) bypass is a novel bariatric surgery technique and can be considered for patients with former background of severe gastroesophageal symptoms. The purpose of this research was to compare SASJ bypass outcomes with other techniques during a 6-month follow-up.

METHODS

This is a non-randomized clinical trial conducted on 100 patients, who underwent four types of bariatric surgery (classic Roux-en-Y bypass, SASJ bypass, omega gastric bypass, and sleeve gastrectomy), and each one of these types contained 25 cases, during the time period of 2 years from 2016 to 2018. Patients' information including age, gender, height, basal weight, body mass index (BMI), serum albumin, and hemoglobin A1C were recorded, within 1, 3, and 6 months after their surgery, and also were compared with each other.

RESULTS

Members of the four groups were similar due to their age, gender distribution, height, baseline BMI, hemoglobin A1C, albumin, and also excess weight (P value > 0.05); however, the sleeve gastrectomy group baseline weight was significantly higher compared with the other three groups (P value = 0.013). All of the groups significantly lost weight during this 6-month period, but the comparison between them indicated no statistical difference regarding excess weight loss, BMI, hemoglobin A1C, and albumin (P value > 0.05). The excess weight loss mean during 6 months in SASJ bypass was 34.2 ± 5.4%, which was comparable with other groups.

CONCLUSIONS

The weight loss trend after the SASJ bypass was similar to that of older techniques; consequently this technique can be considered for cases with particular indications due to the reversibility and also more accessible gastric follow-up studies in the SASJ approach. Further researches with longer follow-ups are strongly recommended.

A Retrospective Database Study of Liraglutide Persistence Associated with Glycemic and Body Weight Control in Patients with Type 2 Diabetes

INTRODUCTION

In both randomized controlled trials and real-world studies, liraglutide has demonstrated glycemic and body weight benefits in patients with type 2 diabetes. However, persistence with diabetes medication can be challenging. This study compared glycated hemoglobin (HbA_1c) and other outcomes in patients with type 2 diabetes who continued treatment with liraglutide for over 12 months with those who discontinued treatment earlier, in a real-life setting.

METHODS

This is a retrospective study of adult patients with type 2 diabetes from Maccabi Healthcare Services in Israel, who initiated treatment with liraglutide from 2010 to 2015. Mean HbA_1c and body weight change from initiation to after 24 months was compared between patients who received liraglutide for at least 12 months ("continuers") and those who discontinued within the first year ("discontinuers"). Adjustment for HbA_1c, body weight, and other potentially confounding factors was performed using 1:1 propensity score matching.

RESULTS

The 3580 patients comprised 2695 continuers and 885 discontinuers; 882 patients per group were matched. A significant (p < 0.001) reduction in HbA_1c (- 0.80% vs - 0.32%) was seen in continuers compared with discontinuers, despite higher insulin usage (70.2% vs 59.0%; p < 0.001), and a higher proportion of patients using ≥ 3 oral glucose-lowering drugs (20.6% vs 6.2%; p < 0.001) at 24 months among discontinuers. Mean body weight reduction was greater in continuers than discontinuers (3.57 vs 1.25 kg; p < 0.001).

CONCLUSION

In a real-world setting, persistent use of liraglutide was associated with good glycemic and body weight control.

FUNDING

Novo Nordisk Health Care AG.

Exenatide ameliorates inflammatory response in human rheumatoid arthritis fibroblast-like synoviocytes

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease of unknown etiology characterized by degradation of cartilage and bone, accompanied by unimpeded proliferation of synoviocytes of altered phenotype. In the present study, we investigated the involvement of the glucagon-like peptide 1 (GLP-1) receptor on human fibroblast-like synoviocytes (FLS) in the pathogenesis of RA using the selective GLP-1 agonist exenatide, a licensed drug used for the treatment of type 2 diabetes. Our results indicate that exenatide may play a role in regulating tumor necrosis factor-α-induced mitochondrial dysfunction by increasing mitochondrial membrane potential, oxidative stress by reducing the production of reactive oxygen species, the expression of NADPH oxidase 4, expression of matrix metalloproteinase (MMP)-3 and MMP-13, release of proinflammatory cytokines including interleukin-1β (IL-1β), IL-6, monocyte chemoattractant protein-1, and high-mobility group protein 1, as well as activation of the p38/nuclear factor of κ light polypeptide gene enhancer in B-cells inhibitor, α/nuclear factor κB signaling pathway in primary human RA FLS. These positive results indicate that exenatide may have potential as a therapeutic agent for the treatment and prevention of RA. © 2019 IUBMB Life, 9999(9999):1-9, 2019.

Incremental effect of liraglutide on traditional insulin injections in rats with type 2 diabetes mellitus by maintaining glycolipid metabolism and cardiovascular function

Type 2 diabetes mellitus (T2DM) is characterized by chronic hyperglycemia, damaged insulin secretion and insulin resistance with high morbidity and mortality. Liraglutide (liragl) and insulin are effective hypoglycemic agents used in T2DM treatment. The potential effect of liragl in combination with insulin on T2DM remains unclear. The aim of the current study was to explore effects of liragl combined with insulin on glycolipid metabolism and cardiovascular function in rats with diabetes. A diabetes model was established in Sprague Dawley rats exposed to a high calorie and high sugar diet in conjunction with intraperitoneal injections of streptozotocin. Results indicated that liragl or insulin used alone decreased glucose and elevated insulin and c-peptide levels. However, their combination revealed greater effects. A significant increase in high-density lipoprotein cholesterol levels along with a decrease in total cholesterol, triglycerides and low-density lipoprotein cholesterol were observed in liragl- and insulin-treated rats compared with STZ-induced diabetes rats. Furthermore, co-administration of liragl and insulin significantly decreased sterol regulatory element-binding protein 1 levels and increased adenosine 5'-monophosphate kinase-α1 and carnitine palmitoyltransferase 1 expression. Combining liragl with insulin reduced myocardial hypertrophy level and gaps between cardiomyocytes compared with liragl or insulin treatment alone. Caspase-3 expression was significantly decreased by combination treatment of liragl and insulin. Oxidative damage was significantly decreased by co-administration of liragl and insulin through enhancing superoxide dismutase expression and reducing malondialdehyde. Furthermore, combination of liragl and insulin significantly reduced myocardial enzyme expression, including myoglobin, creatine kinase-muscle/brain and cardiac troponin I. In summary, the current study demonstrated synergistic effects of liragl and insulin injections on a T2DM rat model by maintaining glycolipid metabolism and cardiovascular function.

Protective effects of alogliptin against TNF-α-induced degradation of extracellular matrix in human chondrocytes

Osteoarthritis (OA) is a common debilitating disease most prevalent among the elderly population worldwide. Excessive degradation of the articular extracellular matrix is a pivotal event in the development of OA. Preventative treatments against the destruction of type II collagen and aggrecan, the two main components of the articular extracellular matrix, may serve as a novel therapy against the progression of OA. In the current study, we investigated whether the DPP-4 inhibitor alogliptin could prevent degradation of the articular extracellular matrix in human primary chondrocytes. Pretreatment with alogliptin successfully prevented degradation of type II collagen and aggrecan in a dose-dependent manner by reducing increased expression of MMP-1, -3, and -13 as well as ADAMTS-4 and -5 induced by treatment with TNF-α. Furthermore, pretreatment with alogliptin also reduced TNF-α-induced expression of IKKα/β, IκBα and NF-κB in human primary chondrocytes. This suggests that DPP-4 inhibitors such as alogliptin may be used as an effective preventative therapy against continued destruction of the articular extracellular matrix in OA.

Treatment approach to type 2 diabetes: Past, present and future

Type 2 diabetes mellitus (DM) is a lifelong metabolic disease, characterized by hyperglycaemia which gradually leads to the development and progression of vascular complications. It is recognized as a global burden disease, with substantial consequences on human health (fatality) as well as on health-care system costs. This review focuses on the topic of historical discovery and understanding the complexity of the disease in the field of pathophysiology, as well as development of the pharmacotherapy beyond insulin. The complex interplay of insulin secretion and insulin resistance developed from previously known "ominous triumvirate" to "ominous octet" indicate the implication of multiple organs in glucose metabolism. The pharmacological approach has progressed from biguanides to a wide spectrum of medications that seem to provide a beneficial effect on the cardiovascular system. Despite this, we are still not achieving the target treatment goals. Thus, the future should bring novel antidiabetic drug classes capable of acting on several levels simultaneously. In conclusion, given the raising burden of type 2 DM, the best present strategy that could contribute the most to the reduction of morbidity and mortality should be focused on primary prevention.

Efficacy and safety of alogliptin in patients with type 2 diabetes mellitus: A multicentre randomized double-blind placebo-controlled Phase 3 study in mainland China, Taiwan, and Hong Kong

BACKGROUND

This study determined the efficacy and safety of once-daily oral alogliptin in patients from mainland China, Taiwan, and Hong Kong with type 2 diabetes mellitus.

METHODS

In this Phase 3 multicenter double-blind placebo-controlled 16-week trial, 506 patients were randomized to receive once-daily alogliptin 25 mg or placebo: 185 in the monotherapy group, 197 in the add-on to metformin group, and 124 in the add-on to pioglitazone group. The primary efficacy variable was the change from baseline (CFB) in HbA1c at Week 16; other efficacy measures included CFB to Week 16 in fasting plasma glucose (FPG), incidence of marked hyperglycemia (FPG ≥11.1 mmol/L), and the incidence of clinical HbA1c ≤6.5 % (48 mmol/mol) and ≤7.0 % (53 mmol/mol) at Week 16. Safety was assessed throughout the trial.

RESULTS

Alogliptin monotherapy provided a significantly greater decrease in HbA1c from baseline to Week 16 compared with placebo (-0.58 %; 95 % confidence interval [CI] -0.78 %, -0.37 %; P < 0.001). As an add-on to metformin or pioglitazone, alogliptin also significantly decreased HbA1c compared with placebo (-0.69 % [95 % CI -0.87 %, -0.51 %; P < 0.001] and -0.52 % [95 % CI -0.75 %, -0.28 %; P < 0.001], respectively). In any treatment group versus placebo, alogliptin led to greater decreases in FPG (P ≤ 0.004) and a higher percentage of patients who achieved an HbA1c target of ≤6.5 % and ≤7.0 % (P ≤ 0.003). No weight gain was observed in any treatment group. A similar percentage of patients experienced drug-related, treatment-emergent adverse events in the alogliptin and placebo arms. Four and two patients in the alogliptin and placebo arms, respectively, experienced mild or moderate hypoglycemia.

CONCLUSIONS

Alogliptin 25 mg once daily reduced HbA1c and FPG and enhanced clinical response compared with placebo when used as monotherapy or as an add-on to metformin or pioglitazone. Therapy with alogliptin was well tolerated.

FAM3D inhibits glucagon secretion via MKP1-dependent suppression of ERK1/2 signaling

Dysregulated glucagon secretion is a hallmark of type 2 diabetes (T2D). To date, few effective therapeutic agents target on deranged glucagon secretion. Family with sequence similarity 3 member D (FAM3D) is a novel gut-derived cytokine-like protein, and its secretion timing is contrary to that of glucagon. However, the roles of FAM3D in metabolic disorder and its biological functions are largely unknown. In the present study, we investigated whether FAM3D modulates glucagon production in mouse pancreatic alpha TC1 clone 6 (αTC1-6) cells. Glucagon secretion, prohormone convertase 2 (PC2) activity, and mitogen-activated protein kinase (MAPK) pathway were assessed. Exogenous FAM3D inhibited glucagon secretion, PC2 activity, as well as extracellular-regulated protein kinase 1/2 (ERK1/2) signaling and induced MAPK phosphatase 1 (MKP1) expression. Moreover, knockdown of MKP1 and inhibition of ERK1/2 abolished and potentiated the inhibitory effect of FAM3D on glucagon secretion, respectively. Taken together, FAM3D inhibits glucagon secretion via MKP1-dependent suppression of ERK1/2 signaling. These results provide rationale for developing the therapeutic potential of FAM3D for dysregulated glucagon secretion and T2D.

Adjuvant Liraglutide and Insulin Versus Insulin Monotherapy in the Closed-Loop System in Type 1 Diabetes: A Randomized Open-Labeled Crossover Design Trial

BACKGROUND

The closed-loop (CL) system delivers insulin in a glucose-responsive manner and optimal postprandial glycemic control is difficult to achieve with the algorithm and insulin available. We hypothesized that adjunctive therapy with liraglutide, a once-daily glucagon-like peptide-1 agonist, would be more effective in normalizing postprandial hyperglycemia versus insulin monotherapy in the CL system, in patients with type 1 diabetes.

METHODS

This was a randomized, controlled, open-label, crossover design trial comparing insulin monotherapy versus adjuvant subcutaneous liraglutide 1.2 mg and insulin, using the CL system in 15 patients. Blood glucose (BG), insulin, and glucagon concentrations were analyzed.

RESULTS

The liraglutide arm was associated with overall decreased mean BG levels (P = .0002). The average BG levels from 8:00 pm (day 1) to 9:00 pm (day 2) were lower in the liraglutide arm (144.6 ± 36.31 vs 159.7 ± 50.88 mg/dl respectively; P = .0002). Two-hour postbreakfast and lunch BG profiles were better in the liraglutide arm (P < .05) and the insulin and glucagon assay values were lower (P < .0001). Postprandially, the area under the curve (AUC) for 2-hour postbreakfast and lunch BG levels were significant (P = .01, P = .03) and the AUC for glucagon, postbreakfast (P < .0001) and lunch (P < .05), was also significant. The incidence of hypoglycemia did not differ between arms (P = .83, Fisher's exact test). Overall, adjunct liraglutide therapy plus CL was well tolerated even with expected side effects.

CONCLUSION

This is a proof-of-concept study showing liraglutide can be a potential adjunctive therapy in addition to CL with insulin to reduce postprandial hyperglycemia in type 1 diabetes.

Cut to the chase: a review of CD26/dipeptidyl peptidase-4's (DPP4) entanglement in the immune system

CD26/DPP4 (dipeptidyl peptidase 4/DP4/DPPIV) is a surface T cell activation antigen and has been shown to have DPP4 enzymatic activity, cleaving-off amino-terminal dipeptides with either L-proline or L-alanine at the penultimate position. It plays a major role in glucose metabolism by N-terminal truncation and inactivation of the incretins glucagon-like peptide-1 (GLP) and gastric inhibitory protein (GIP). In 2006, DPP4 inhibitors have been introduced to clinics and have been demonstrated to efficiently enhance the endogenous insulin secretion via prolongation of the half-life of GLP-1 and GIP in patients. However, a large number of studies demonstrate clearly that CD26/DPP4 also plays an integral role in the immune system, particularly in T cell activation. Therefore, inhibition of DPP4 might represent a double-edged sword. Apart from the metabolic benefit, the associated immunological effects of long term DPP4 inhibition on regulatory processes such as T cell homeostasis, maturation and activation are not understood fully at this stage. The current data point to an important role for CD26/DPP4 in maintaining lymphocyte composition and function, T cell activation and co-stimulation, memory T cell generation and thymic emigration patterns during immune-senescence. In rodents, critical immune changes occur at baseline levels as well as after in-vitro and in-vivo challenge. In patients receiving DPP4 inhibitors, evidence of immunological side effects also became apparent. The scope of this review is to recapitulate the role of CD26/DPP4 in the immune system regarding its pharmacological inhibition and T cell-dependent immune regulation.

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

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

Safety and Efficacy of Liraglutide in Patients With Type 2 Diabetes and End-Stage Renal Disease: An Investigator-Initiated, Placebo-Controlled, Double-Blind, Parallel-Group, Randomized Trial

OBJECTIVE

To evaluate parameters related to safety and efficacy of liraglutide in patients with type 2 diabetes and dialysis-dependent end-stage renal disease (ESRD).

RESEARCH DESIGN AND METHODS

Twenty-four patients with type 2 diabetes and ESRD and 23 control subjects with type 2 diabetes and normal kidney function were randomly allocated to 12 weeks of double-blind liraglutide (titrated to a maximum dose of 1.8 mg) or placebo treatment (1:1) injected subcutaneously once daily as add on to ongoing antidiabetic treatment. Dose-corrected plasma trough liraglutide concentration was evaluated at the final trial visit as the primary outcome measure using a linear mixed model.

RESULTS

Twenty patients with ESRD (1:1 for liraglutide vs. placebo) and 20 control subjects (1:1) completed the study period. Dose-corrected plasma trough liraglutide concentration at the final visit was increased by 49% (95% CI 6-109, P = 0.02) in the group with ESRD compared with the control group. Initial and temporary nausea and vomiting occurred more frequently among liraglutide-treated patients with ESRD compared with control subjects (P < 0.04). Glycemic control tended to improve during the study period in both liraglutide-treated groups as assessed by daily blood glucose measurements (P < 0.01), and dose of baseline insulin was reduced in parallel (P < 0.04). Body weight was reduced in both liraglutide-treated groups (-2.4 ± 0.8 kg [mean ± SE] in the group with ESRD, P = 0.22; -2.9 ± 1.0 kg in the control group, P = 0.03).

CONCLUSIONS

Plasma liraglutide concentrations increased during treatment in patients with type 2 diabetes and ESRD, who experienced more gastrointestinal side effects. Reduced treatment doses and prolonged titration period may be advisable.

Sitagliptin can inhibit the development of hepatic steatosis in high-fructose diet-fed ob/ob mice

The beneficial effect of dipeptidyl peptidase-4 inhibition on diet-induced extra-pancreatic effects, especially on liver tissue remains poorly understood. Thus, we made the experimental designs as follows; five-week-old male ob/ob mice, which develop type 2 diabetic mellitus and nonalcoholic fatty liver disease by taking a high-carbohydrate diet (HCD), were divided into a group in which a HCD was given for 8 weeks as control, and another in which a HCD added with 0.0018% sitagliptin was given for 8 weeks. Hepatic steatosis was seen in all mice, but the mean grade of steatosis in the sitagliptin-administrated mice was significantly decreased. The acetyl-CoA concentrations were lower in sitagliptin-administrated mice, although the differences were not significant. However, the malonyl-CoA concentrations were significantly lower in sitagliptin-administrated mice. The expression of acetyl-CoA carboxylase 1 was inhibited in sitagliptin-administrated mice, irrespective of expressions of carbohydrate responsive element-binding protein (ChREBP) or sterol regulatory element-binding protein (SREBP)-1c. In conclusion, sitagliptin may affect the development of nonalcoholic fatty liver disease by inhibiting the production of malonyl-CoA and thus synthesis of fatty acids in the liver.

Distinct glucose-lowering properties in good responders treated with sitagliptin and alogliptin

BACKGROUND AND OBJECTIVES

All dipeptidyl peptidase 4 (DPP-4) inhibitors display similar glycemic efficacies, although they differ greatly in their chemical structures and pharmacological properties. This may be due to the inclusions of non- or poor-responders in the analysis, thereby masking the real effects of these drugs. The aim of this study was to identify any differences in diabetic parameters only in good responders treated with sitagliptin and alogliptin.

METHODS

Treatment naïve subjects with type 2 diabetes mellitus were assigned to either sitagliptin 25-50 mg/day (n = 69) or alogliptin 12.5-25 mg/day monotherapy (n = 62) for 3 months. Only those who showed good response selected by a novel parameter called A1c index were further analysed (n = 24 for sitagliptin and n = 21 for alogliptin).

RESULTS

At baseline, FBG and BMI were significantly higher and CPR-index was significantly lower in alogliptin good responders. At 3 months, while similar reductions of HbA1c were observed in these two groups, decreases of fasting blood glucose (FBG) were significantly higher in alogliptin good responders. Homeostasis model assessment (HOMA)-R significantly decreased only in alogliptin good responders, while HOMA-B similarly and significantly increased in these two groups. BMI significantly increased only in sitagliptin good responders. Significant negative correlations were observed between A1c index and changes (Δ) of HOMA-B in both groups. By contrast, significant positive and negative correlations were observed between ΔFBG and ΔHOMA-R, and between ΔFBG and ΔHOMA-B, respectively, only in alogliptin good responders.

CONCLUSIONS

These results implicate that the effects on diabetic parameters and the glucose-lowering mechanisms of these two drugs might be different in those who have good response with these drugs. Accordingly, the choice of these drugs may be dependent on the characteristics of the patients.

Pathways targeted by antidiabetes drugs are enriched for multiple genes associated with type 2 diabetes risk

Genome-wide association studies (GWAS) have uncovered >65 common variants associated with type 2 diabetes (T2D); however, their relevance for drug development is not yet clear. Of note, the first two T2D-associated loci (PPARG and KCNJ11/ABCC8) encode known targets of antidiabetes medications. We therefore tested whether other genes/pathways targeted by antidiabetes drugs are associated with T2D. We compiled a list of 102 genes in pathways targeted by marketed antidiabetic medications and applied Gene Set Enrichment Analysis (MAGENTA [Meta-Analysis Gene-set Enrichment of variaNT Associations]) to this gene set, using available GWAS meta-analyses for T2D and seven quantitative glycemic traits. We detected a strong enrichment of drug target genes associated with T2D (P = 2 × 10(-5); 14 potential new associations), primarily driven by insulin and thiazolidinedione (TZD) targets, which was replicated in an independent meta-analysis (Metabochip). The glycemic traits yielded no enrichment. The T2D enrichment signal was largely due to multiple genes of modest effects (P = 4 × 10(-4), after removing known loci), highlighting new associations for follow-up (ACSL1, NFKB1, SLC2A2, incretin targets). Furthermore, we found that TZD targets were enriched for LDL cholesterol associations, illustrating the utility of this approach in identifying potential side effects. These results highlight the potential biomedical relevance of genes revealed by GWAS and may provide new avenues for tailored therapy and T2D treatment design.

DPP-4 inhibitors: pharmacological differences and their clinical implications

INTRODUCTION

Recently, incretin-based therapy was introduced for the treatment of type 2 diabetes (T2D). In particular, dipeptidyl peptidase-4 inhibitors (DPP-4i) (sitagliptin, vildagliptin, saxagliptin, linagliptin and alogliptin) play an increasing role in the management of T2D.

AREAS COVERED

An extensive literature search was performed to analyze the pharmacological characteristics of DPP-4i and their clinical implications.

EXPERT OPINION

DPP-4i present significant pharmacokinetic differences. They also differ in chemical structure, in the interaction with distinct subsites of the enzyme and in different levels of selectivity and potency of enzyme inhibition. Moreover, disparities in the effects on glycated hemoglobin, glucagon-like peptide-1 and glucagon levels and on glucose variability have been observed. However, indirect comparisons indicate that all DPP-4i have a similar safety and efficacy profiles. DPP-4i are preferred in overweight/obese and elderly patients because of the advantages of minimal or no influence on weight gain and low risk of hypoglycemia. For the same reasons, DPP-4i can be safely combined with insulin. However, currently cardiovascular outcomes related to DPP-4i are widely debated and the available evidence is controversial. Today, long-term studies are still in progress and upcoming results will allow us to better define the strengths and limits of this therapeutic class.

Evaluation of the effectiveness of liraglutide and sitagliptin in type 2 diabetes: a retrospective study in UK primary care

OBJECTIVE

Type 2 diabetes is a chronic condition that continues to increase in prevalence in the UK. Incretin-based therapies, including liraglutide and sitagliptin, provide adequate blood glucose control. Clinical trials have shown that liraglutide offers greater glycaemic control and body weight reduction in comparison to sitagliptin. We aimed to assess the effectiveness of liraglutide and sitagliptin in routine clinical practice.

MATERIALS AND METHODS

We designed and conducted a retrospective database analysis in primary care using the Clinical Practice Research Datalink in the UK. Patients aged ≥ 18 years, diagnosed with type 2 diabetes and prescribed liraglutide or sitagliptin between July 2009 and July 2012, were included in the study. Glycaemic and weight control were investigated 6 months after treatment initiation.

RESULTS

A total of 287 liraglutide and 2781 sitagliptin patients were identified. Compared with sitagliptin, liraglutide recipients had greater reductions in HbA1c (%) (-0.90 vs. -0.57, p < 0.01), weight (kg) (-3.78 vs. -1.12, p < 0.001), BMI (kg/m(2) ) (-1.30 vs. -0.39, p < 0.001) and systolic blood pressure (mmHg) (-3.91 vs. -0.39, p < 0.001) after 6 months of treatment. When controlling for potential confounders, liraglutide was more likely than sitagliptin to achieve an HbA1c reduction ≥ 1% (OR = 2.29, 95% CI 1.62-3.25), an HbA1c reduction ≥ 1% and a weight reduction ≥ 3% (OR = 2.99; 95% CI 2.00-4.48) and a target HbA1c < 7% (OR = 2.11; 95% CI 1.45-3.07) after 6 months of treatment.

CONCLUSIONS

Clinical trials show superior glycaemic control and weight reduction with liraglutide compared with sitagliptin. This finding is reflected in routine clinical practice in the UK.

Alogliptin: a new dipeptidyl peptidase-4 inhibitor with potential anti-atherogenic properties

OBJECTIVES

The aim of this study is to evaluate the effects of alogliptin on metabolic profiles in relation to those of glycemic control.

PATIENTS AND METHODS

Treatment naïve subjects with type 2 diabetes received 12.5-25 mg/d alogliptin monotherapy (n = 59). A novel parameter called A1c index was used to assess the glycemic efficacy. The subjects were divided into three groups according to this index; super-responders, average responders and poor-responders. At 3 months, levels of the metabolic parameters were compared with those at baseline between super-responders (n = 20) and poor-responders (n = 21).

RESULTS

At baseline, total cholesterol, non-high density lipoprotein cholesterol and atherogenic index were significantly higher in super-responders than poor-responders. At 3 months, significant increases of beta-cell function (HOMA-B) and decreases of insulin resistance (HOMA-R) or these atherogenic lipids were observed in super-responders, while significant increases of HOMA-R were observed in poor-responders. Significant correlations were observed between A1c index and the changes of these atherogenic lipids. In super-responders, significant correlations were observed between the changes (Δ) of glycemic parameters (A1c index or fasting blood sugar) and ΔHOMA-R and/or ΔHOMA-B, while in poor-responders, significant correlations were observed between ΔHOMA-R and ΔHOMA-B. Lean subjects gained weight and the changes of body mass index had significant negative correlations with A1c index.

CONCLUSIONS

These results indicate that (1) glucose lowering efficacy of alogliptin is closely linked to atherogenic lipids. (2) alogliptin can down-regulate atherogenic lipids. (3) glycemic efficacy of alogliptin appears to be determined by the balance of its capacity in modulating insulin resistance and beta-cell function.

Efficacy and safety of linagliptin as monotherapy or add-on treatment in Asian patients with suboptimal glycemic control: a pooled analysis

AIMS

To evaluate the efficacy and safety of the dipeptidyl peptidase (DPP)-4 inhibitor linagliptin in Asian patients with type 2 diabetes mellitus (T2DM), a rapidly increasing population.

METHODS

Data were pooled for Asian patients receiving linagliptin orally once daily, as monotherapy or added to existing oral antidiabetes therapies, in multinational randomized placebo-controlled clinical trials. Efficacy data were taken from four pivotal trials with 24-week durations to allow for robust efficacy assessment. Safety data were pooled from a wider group of 10 trials with varying durations to capture the largest possible incidence of adverse events (AEs). The primary efficacy endpoint was change from baseline to week 24 in HbA1c. AEs were analyzed descriptively.

RESULTS

Mean baseline HbA1c (±SD) in this population was 8.2 ± 0.9%. Placebo-corrected mean change in HbA1c after 24 weeks was -0.79% (95% confidence interval [CI]: -0.92 to -0.67; p < 0.0001). Placebo-corrected mean change in fasting plasma glucose was -17.8 ± 2.4 mg/dL (95% CI: -22.6, -13.0; p < 0.0001). In a small subgroup, mean post-prandial glucose was reduced by a placebo-corrected -56.9 ± 14.0 mg/dL (95% CI: -85.2, -28.5). AEs occurred in 58.0% of linagliptin patients (serious AEs in 2.4%) and 58.2% of placebo patients (serious AEs in 3.0%).

CONCLUSIONS

This study was limited by the post hoc nature of the analysis, and because the pooling did not differentiate between geographically distant Asian regions. Nonetheless, this analysis provides evidence that linagliptin was efficacious and well tolerated as monotherapy or added to other oral antidiabetes therapies in Asian patients with T2DM.

Linagliptin improved glycaemic control without weight gain or hypoglycaemia in patients with type 2 diabetes inadequately controlled by a combination of metformin and pioglitazone: a 24-week randomized, double-blind study

AIMS

To investigate the efficacy and safety of the dipeptidyl peptidase-4 inhibitor linagliptin in patients with Type 2 diabetes mellitus inadequately controlled by a combination of metformin and pioglitazone.

METHODS

This was a multi-centre, phase 3, randomized, double-blind, placebo-controlled study comparing linagliptin 5 mg once daily (n = 183) and placebo (n = 89) as add-on to metformin and pioglitazone. The primary endpoint was the change from baseline in glycated haemoglobin (HbA1c ) after 24 weeks.

RESULTS

The placebo-corrected adjusted mean (se) change in HbA1c from baseline to 24 weeks was -6 (1) mmol/mol [-0.57 (0.13)%] (P < 0.0001). In patients with baseline HbA1c ≥ 53 mmol/mol (7.0%), 32.4% of patients in the linagliptin group and 13.8% in the placebo group achieved HbA1c < 53 mmol/mol (7.0%) (odds ratio 2.94; P = 0.0033). The placebo-corrected adjusted mean (se) change from baseline in fasting plasma glucose at week 24 was -0.57 (0.26) mmol/l [-10.4 (4.7) mg/dl] (P = 0.0280). The incidence of serious adverse events was 2.2% with linagliptin and 3.4% with placebo. Investigator-defined hypoglycaemia occurred in 5.5% of the linagliptin group and 5.6% of the placebo group. No meaningful changes in mean body weight were noted for either group.

CONCLUSIONS

Linagliptin as add-on therapy to metformin and pioglitazone produced significant and clinically meaningful improvements in glycaemic control, without an additional risk of hypoglycaemia or weight gain (Clinical Trials Registry No: NCT 00996658).

Novel AGLP-1 albumin fusion protein as a long-lasting agent for type 2 diabetes

Glucagon like peptide-1 (GLP-1) regulates glucose mediated-insulin secretion, nutrient accumulation, and β-cell growth. Despite the potential therapeutic usage for type 2 diabetes (T2D), GLP-1 has a short half-life in vivo (t_1/2 ＜2 min). In an attempt to prolong half-life, GLP-1 fusion proteins were genetically engineered: GLP-1 human serum albumin fusion (GLP-1/HSA), AGLP-1/HSA which has an additional alanine at the N-terminus of GLP-1, and AGLP-1-L/HSA, in which a peptide linker is inserted between AGLP-1 and HSA. Recombinant fusion proteins secreted from the Chinese Hamster Ovary-K1 (CHO-K1) cell line were purified with high purity (＞96%). AGLP-1 fusion protein was resistant against the dipeptidyl peptidase-IV (DPP-IV). The fusion proteins activated cAMP-mediated signaling in rat insulinoma INS-1 cells. Furthermore, a C57BL/6N mice pharmacodynamics study exhibited that AGLP-1-L/HSA effectively reduced blood glucose level compared to AGLP-1/HSA. [BMB Reports 2013; 46(12): 606-610]

Diabetes and cardiovascular disease: focus on glucagon-like peptide-1 based therapies

Type 2 diabetes is a well known risk factor for cardiovascular disease (CVD). While glycemic control has consistently been shown to prevent microvascular complications, large randomized trials have not demonstrated the same consistent beneficial effects of intensive glycemic control in improving cardiovascular (CV) outcomes. Thus, optimal glucose control alone is not sufficient to reduce CV risk. Aggressive management of CV risk factors such as blood pressure, lipids, and body weight is also necessary. A growing body of evidence suggests that the recently available glucagon-like peptide 1 receptor (GLP-1R) agonists have beneficial CV effects beyond glucose control. Studies have demonstrated beneficial effects in the myocardium, endothelium, vasculature and various markers of cardiovascular risk such as body weight, blood pressure and dyslipidemia. Despite the growing evidence, large, randomized, blinded clinical trials with hard CV endpoints have not been performed. Most human studies have been small, and have focused on surrogate endpoints. The findings need to be confirmed by prospective, randomized cardiovascular outcomes trials. In this review we examine the GLP-1R agonist data on weight reduction, blood pressure lowering, beneficial changes in dyslipidemia, and improvements in myocardial and endothelial function. The safety as well as potential role of these agents in treatment regimens for type 2 diabetes is also addressed.

Teneligliptin as an initial therapy for newly diagnosed, drug naive subjects with type 2 diabetes

BACKGROUND

Teneligliptin is a novel, highly selective dipeptidyl peptidase-4 (DPP-4) inhibitor. The aim of this study is to explore the glycemic and non-glycemic efficacies of teneligliptin as an initial therapy.

METHODS

Newly diagnosed, drug naive Japanese subjects with type 2 diabetes (T2DM) were assigned to 20 mg/day teneligliptin monotherapy (n = 31). At 3 months, levels of glycemic and other parameters were compared with those at baseline.

RESULTS

Significant reductions of HbA1c (from 10.34 ± 2.06 to 8.38 ± 2.23%) and fasting blood glucose (FGB, from 211.3 ± 68.4 to 167.3 ± 70.2 mg/dL) levels were observed without any clinically significant adverse events. However, significant increases of uric acids (UA) levels were observed and two subjects reported mild hypoglycemic events. Homeostasis model assessment-B (HOMA-B) levels significantly increased, while high HOMA-R levels significantly decreased. Significant correlations were observed between the changes (Δ) of HbA1c and those of HOMA-B, and between ΔFBG and ΔHOMA-R. No changes in lipid and body weight were noted.

CONCLUSIONS

Teneligliptin might be effectively and safely used as an initial therapy for newly diagnosed T2DM. Glycemic efficacy of teneligliptin is obtained through activating beta-cell function as well as decreasing insulin resistance.

Corticotropin-releasing hormone and the sympathoadrenal system are major mediators in the effects of peripherally administered exendin-4 on the hypothalamic-pituitary-adrenal axis of male rats

Glucagon-like peptide-1 (GLP-1) and the GLP-1 receptor agonist, exendin-4 (Ex-4), potently stimulate hypothalamic-pituitary-adrenal (HPA) axis activity after either central or peripheral administration. Because several GLP-1 derivative drugs, including synthetic Ex-4, are currently in use to treat patients with type II diabetes mellitus, the characterization of Ex-4 effects on the HPA axis is highly relevant. Herein, the roles of CRH and AVP on these effects were investigated by administering the antagonists astressin and d(CH2)5Tyr(Me)AVP, respectively. The role of the sympathoadrenal system (SAS) was explored in bilateral adrenal enucleated and guanethidine-treated rats, whereas primary pituitary cell cultures were used to study direct effects on the corticotropes. Astressin completely abrogated (P < .05) the effects of Ex-4 central administration on ACTH secretion but only slightly reduced (by 35%) the ACTH response to Ex-4 peripheral administration. Moreover, astressin significantly (P < .05) decreased the corticosterone response to centrally but not peripherally administered Ex-4, suggesting different mechanisms depending on the route of administration. Pretreatment with d(CH2)5Tyr(Me)AVP failed to diminish either the ACTH or corticosterone response to Ex-4 and no direct effect of Ex-4 or GLP-1 was observed on pituitary cell cultures. In contrast, a significant (P < .05) reduction in the corticosterone response elicited by Ex-4 peripheral administration was observed in enucleated and guanethidine-treated rats, indicating a role of the SAS in the glucocorticoid stimulatory effects of Ex-4. Our data demonstrate that the effects of Ex-4 on the HPA axis are partially mediated by CRH and the sympathoadrenal system, and stress the relevance of Ex-4 as a corticosterone secretagogue.

Evolution of abnormal plasma glucagon responses to mixed-meal feedings in youth with type 1 diabetes during the first 2 years after diagnosis

OBJECTIVE

To examine the evolution of the dysregulated glucagon responses to mixed-meal tolerance tests (MMTTs) in youth with recent-onset type 1 diabetes (T1D).

RESEARCH DESIGN AND METHODS

MMTTs were performed in 25 youth (9-18 years of age) with 1.5-12 months disease duration (year 1); 22 subjects were restudied 1 year later (year 2). Twenty nondiabetic (ND) control children were also studied.

RESULTS

In T1D children, MMTT-stimulated increases in glucagon were significantly greater than that in ND children (median increments: year 1, 21 pg/mL [16-30]; year 2, 25 pg/mL [16-30]; ND, 9 pg/mL [5-16]; P = 0.001 and P < 0.001, respectively).

CONCLUSIONS

In comparison with ND control children, exaggerated plasma glucagon responses to mixed-meal feedings are observed in youth with T1D within the first 2 years of diagnosis. Further studies to determine whether suppression of these abnormal responses may help to improve glycemic control are warranted.

Randomized controlled clinical trial of a combination therapy of vildagliptin plus an α-glucosidase inhibitor for patients with type II diabetes mellitus

The aim of this study was to assess the efficacy of a combination therapy of vildagliptin plus an α-glucosidase inhibitor for patients with type II diabetes mellitus. Type II diabetic patients exhibiting poor glycemic control following α-glucosidase inhibitor treatment for at least two months were selected and randomly distributed into vildagliptin and placebo groups. The body weight, fasting blood glucose (FBG), postprandial glucose (PPG), glycated hemoglobin (HBA1c) and blood lipid levels and hepatorenal functions of the patients were determined before and 12 weeks after the trial. Following the trial, the FBG, PPG, HbA1c, cholesterol (CHOL) and triglyceride (TG) levels in the vildagliptin group were significantly decreased compared with the pretreatment levels (P<0.05), whereas only the PPG level in the placebo group decreased (P<0.05). The FBG, PPG and HbA1c levels in the vildagliptin group were markedly lower than those in the placebo group 12 weeks after the trial. A comparison of the body weights and hepatorenal functions before and after the trial or between groups did not show statistically significant differences. The combination therapy of vildagliptin plus an α-glucosidase inhibitor effectively reduced the FBG, PPG and HbA1c levels in patients without inducing weight gain or hepatorenal dysfunction. However, the therapy may have caused a reduction in the blood lipid levels.

A Brief History of the Development of Diabetes Medications

This article provides an overview of the development of insulins, oral agents, and noninsulin injectable agents used in the management of hyperglycemia in patients with diabetes. It also briefly reviews the pharmacological impact and salient side effects of these medications.

Separation of alogliptin enantiomers in cyclodextrin-modified capillary electrophoresis: a validated method

The single enantiomer drug, alogliptin (Alo, Nesina®) is a novel, orally available and selective dipeptidyl peptidase-4 inhibitor used for the treatment of type II diabetes. Following its pKa determination by CE-pH titration, a validated chiral CE method has been developed to separate Alo enantiomers. Preliminary screening of the native CDs and their ten derivatives revealed that sulfopropylated-γ-CD, sulfopropylated-β-CD and sulfopropylated-γ-CD, sulfobutyl-ether-β-CD (SBE-β-CD) and sulfobutyl-ether-γ-CD enabled enantioresolution. Furthermore, cavity size dependent enantiomer migration order reversal was observed between γ- and β-CD derivatives. To improve enantioseparation, buffer composition and pH, CD concentration, applied voltage, temperature, and injection parameters were optimized for the Alo/ SBE-β-CD system, yielding a resolution of 8.34. RSD percentage of the resolution value, migration times, and corrected peak areas were below 3 and 5% during testing repeatability and intermediate precision. LOD and LOQ values were found to be 2 and 6 μg/mL, respectively, for each enantiomer. Calibration lines ranging from 6 to 250 μg/mL were constructed with r(2) > 0.9997. Robustness could be successfully verified by using the Plackett-Burman statistical experimental design. The optimized system containing 5 mM SBE-β-CD in a 25 mM acetate buffer at pH 4.75 was found promising to detect 0.1% distomer in the presence of the API.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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