The Placement of DPP-4 Inhibitors in Clinical Practice Recommendations for the Treatment of Types 2 Diabetes

ObjectiveTo review the most recent clinical data on the safety and efficacy of dipeptidyl peptidase-4 (DPP-4) inhibitors and to evaluate their position in current treatment guidelines and algorithms.MethodsPubMed searches were performed to identify published data regarding both the safety and efficacy of DPP-4 inhibitors approved for use in the United States and clinical guidelines describing recommendations for their use.ResultsIn the past 2 years, more than 100 publications have added clinical trial data on DPP-4 inhibitors to the medical literature. Since becoming available in 2006, these agents have demonstrated an excellent safety/tolerability profile, and as add-on to metformin, DPP-4 inhibitors may have comparable glycemic efficacy as other oral agents. As a result, DPP-4 inhibitors have assumed roles in clinical practice guidelines and treatment algorithms that are comparable to the sulfonylurea class. Advantages of DPP-4 inhibitors include an oral route of administration, a mechanism of action based on glucose-stimulated insulin secretion, and a low risk of hypoglycemia. The main disadvantage associated with this class is a relatively high cost. There is also less clinical experience with DPP-4 agents than classes of agents that have been in use for decades; however, long-term data on the safety and efficacy of DPP-4 agents will be available in the near future to refine their place in therapy. From 2 large clinical trials recently reported, EXAMINE and SAVOR, this class of agents does not increase overall adverse cardiovascular outcomes nor the risk of pancreatitis or pancreatic cancer.ConclusionBased on comparisons of nonglycemic effects such as risk of hypoglycemia, weight gain, and durability, DPP-4 inhibitors may be considered as an alternative to sulfonylureas. However, direct cost may be a determining factor in the choice of therapy. (Endocr Pract. 2013;19:1050-1061)     

Potential Place of SGLT2 Inhibitors in Treatment Paradigms for type 2 Diabetes Mellitus

Objective: Following the first Food and Drug Administration (FDA) approval in 2013, sodium glucose cotransporter 2 (SGLT2) inhibitors have generated much interest among physicians treating patients with type 2 diabetes mellitus (T2DM). Here, the role in treatment with this drug class is considered in the context of T2DM treatment paradigms.Methods: The clinical trials for the SGLT2 inhibitors are examined with a focus on canagliflozin, dapagliflozin, and empagliflozin.Results: Evidence from clinical trials in patients with T2DM supports the use of SGLT2 inhibitors either as monotherapy or in addition to other glucose-lowering treatments as adjuncts to diet and exercise, and we have gained significant clinical experience in a relatively short time.Conclusion: The drugs appear to be useful in a variety of T2DM populations, contingent primarily on renal function. Most obviously, SGLT2 inhibitors appear to be well suited for patients with potential for hypoglycemia or weight gain. In clinical trials, patients treated with SGLT2 inhibitors have experienced moderate weight loss and a low risk of hypoglycemic events except when used in combination with an insulin secretagogue. In addition, SGLT2 inhibitors have been shown to reduce blood pressure, so they may be beneficial in patients with T2DM complicated by hypertension. SGLT2 inhibitors were incorporated into the 2015 American Diabetes Association (ADA)/European Association for the Study of Diabetes (EASD) position statement on the management of hyperglycemia and received an even more prominent position in the American Association of Clinical Endocrinologists (AACE)/American College of Endocrinology (ACE) comprehensive diabetes management guidelines and algorithm.Abbreviations: AE = adverse event A1C = glycated hemoglobin CI = confidence interval CKD = chronic kidney disease DKA = diabetic ketoacidosis DPP-4 = dipeptidyl peptidase 4 eGFR = estimated glomerular filtration rate FDA = Food and Drug Administration FPG = fasting plasma glucose GLP-1 = glucagon-like peptide 1 HDL-C = high-density lipoprotein cholesterol HR = hazard ratio LADA = late-onset autoimmune diabetes of adulthood LDL-C = low-density lipoprotein cholesterol MACE = major adverse cardiovascular events SGLT1 = sodium glucose cotransporter 1 SGLT2 = sodium glucose cotransporter 2 T1DM = type 1 diabetes mellitus T2DM = type 2 diabetes mellitus UACR = urine albumin to creatinine ratio     

Reshaping Diabetes Care: The Fundamental Role of Dipeptidyl Peptidase-4 Inhibitors and Glucagon-Like Peptide-1 Receptor Agonists in Clinical Practice

ObjectiveTo update clinicians on the most recent safety and efficacy data on current incretin-based strategies for the treatment of type 2 diabetes (T2D).MethodsTitle 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, sita-gliptin, and vildagliptin.ResultsThe 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.ConclusionIncretin-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. (Endocr Pract. 2013;19:718-728)     

Efficacy and Safety of Dipeptidyl Peptidase-4 Inhibitors in Type 2 Diabetes Mellitus Patients with Moderate to Severe Renal Impairment: A Systematic Review and Meta-Analysis

Objective

To perform a systematic review and meta-analysis regarding the efficacy and safety of dipeptidyl peptidase-4 (DDP-4) inhibitors (“gliptins”) for the treatment of type 2 diabetes mellitus (T2DM) patients with moderate to severe renal impairment.

Methods

All available randomized-controlled trials (RCTs) that assessed the efficacy and safety of DDP-4 inhibitors compared with placebo, no treatment, or active drugs were identified using PubMed, EMBASE, Cochrane CENTRAL, conference abstracts, clinical trials.gov, pharmaceutical company websites, the FDA, and the EMA (up to June 2014). Two independent reviewers extracted the data, and a random-effects model was applied to estimate summary effects.

Results

Thirteen reports of ten studies with a total of 1,915 participants were included in the final analysis. Compared with placebo or no treatment, DPP-4 inhibitors reduced HbA1c significantly (−0.52%, 95%CI −0.64 to −0.39) and had no increased risk of hypoglycemia (RR 1.10, 95%CI 0.92 to 1.32) or weight gain. In contrast to glipizide monotherapy, DPP-4 inhibitors showed no difference in HbA1c lowering effect (−0.08%, 95% CI −0.40 to 0.25) but had a lower incidence of hypoglycemia (RR 0.40, 95%CI 0.23 to 0.69). Furthermore, DPP-4 inhibitors were well-tolerated, without any additional mortality and adverse events. However, the quality of evidence was mostly as low, as assessed using the GRADE system for each outcome.

Conclusions

DPP-4 inhibitors are effective at lowering HbA1c in T2DM patients with moderate to severe renal impairment. DPP-4 inhibitors also have a potential advantage in lowering the risk of adverse events. Regarding the low quality of the evidence according to GRADE, additional well-designed randomized trials that focus on the safety and efficacy of DPP-4 inhibitors in various CKD stages are needed urgently.     

Discovery of triazole-based uracil derivatives bearing amide moieties as novel dipeptidyl peptidase-IV inhibitors

Dipeptidyl peptidase-IV (DPP-4) is a validated target for T2DM treatment. We previously reported a novel series of triazole-based uracil derivatives bearing aliphatic carboxylic acids with potent DPP-4 inhibitory activities in vitro, but these compounds showed poor hypoglycemic effects in vivo. Herein we further optimized the triazole moiety by amidation of the carboxylic acid to improve in vivo activities. Two series of compounds 3a-f and 4a-g were designed and synthesized. By screening in DPP-4, compound 4c was identified as a potent DPP-4 inhibitor with the IC₅₀ value of 28.62 nM. Docking study revealed compound 4c has a favorable binding mode and interpreted the SAR of these analogs. DPP-8 and DPP-9 tests indicated compound 4c had excellent selectivity over DPP-8 and DPP-9. Further in vivo evaluations revealed that compound 4c showed more potent hypoglycemic activity than its corresponding carboxylic acid in ICR mice and dose-dependently reduced glucose levels in type 2 diabetic C57BL/6 mice. The overall results have shown that compound 4c could be a promising lead for further development of novel DPP-4 agents treating T2DM.     

Elevated Amylase and Lipase Levels in Patients Using Glucagonlike Peptide-1 Receptor Agonists or Dipeptidyl-Peptidase-4 Inhibitors In the Outpatient Setting

ObjectiveTo investigate the effects of glucagonlike peptidase-1 (GLP-1) receptor agonists and dipeptidyl-peptidase-4 (DPP-4) inhibitors on serum amylase and serum lipase levels in patients with type 2 diabetes.MethodsIn 90 patients with type 2 diabetes, treatment was initiated with a GLP-1 agonist or a DPP-4 inhibitor. A comparison group consisted of 33 patients with type2 diabetes and similar characteristics who were not prescribed these agents. Baseline serum amylase and lipase levels were measured in all patients and repeated periodically. We determined the percentage of patients with elevated levels of serum amylase or lipase (or both) in both groups.ResultsAmong all 90 patients who received a GLP-1 receptor agonist or a DPP-4 inhibitor, 32 (36%) had an increase in serum amylase or lipase (or both) in comparison with 6 of 33 patients (18%) with such increases in the comparison group. Interestingly, the serum lipase levels increased more than the serum amylase values in all groups. To ascertain that this was not a chance laboratory error, serum samples were submitted to a second independent laboratory, and the same results were obtained. Usually, use of the medication was discontinued when serum lipase or amylase values were found to be elevated at any level.ConclusionBoth GLP-1 receptor agonists and DPP-4 inhibitors are associated with increased levels of serum lipase more than serum amylase in many patients with type2 diabetes, possibly suggesting the presence of pancreatic inflammation. Whether this finding may potentially lead to acute pancreatitis or chronic pancreatitis, as reported in rat models, is currently unknown. Careful observation of patients taking these medications may be prudent. (Endocr Pract. 2012;18:472-477)     

Preservation of Beta-Cell Function in Type 2 Diabetes

ObjectiveTo review available data on preservation and potential improvement of beta-cell function in patients with type 2 diabetes mellitus (T2DM) with use of currently available strategies and agents.MethodsUsing key words, we performed a MEDLINE search of the relevant literature published through 2009 regarding the effects of available agents on beta-cell function in humans with T2DM.ResultsOn the basis of current clinical data, no uniformly effective treatment for beta-cell preservation has been found. Lifestyle intervention and early intensive insulin therapy appear to have some preservative properties on beta-cell function. Glucagonlike peptide-1 agonists, dipeptidyl-peptidase-4 inhibitors, and thiazolidinediones result in maintenance and often improvement of beta-cell function during their active use; however, data on their ability to preserve beta-cell function when patients are not receiving active treatment are limited.ConclusionThe continuous loss of beta-cell mass and beta-cell function is a critical mechanism underlying the progressive deterioration of glycemic control in T2DM. In light of the projected increase in individuals at risk for developing T2DM, strategies and agents aimed at delaying or preventing the progression and inducing a remission of the disease are needed. Future research on this topic should include comparative efficacy trials with washout periods incorporating currently available and novel medications and strategies for preservation of beta cells. (Endocr Pract. 2010;16:1038-1055)     

Safety And Efficacy Of Dpp-4 Inhibitors For The Management Of Hospitalized General Medicine And Surgery Patients with Type 2 Diabetes

Objective: DPP-4 inhibitors (DPP-4i) have been shown to be effective for the management of inpatient diabetes. We report pooled data from 3 prospective studies using DPP-4i in general medicine and surgery patients with type 2 diabetes (T2D).Methods: We combined data from 3 randomized studies comparing DPP-4i alone or in combination with basal insulin or a basal-bolus insulin regimen. Medicine (n = 266) and surgery (n = 319) patients admitted with a blood glucose (BG) between 140 and 400 mg/dL, treated with diet, oral agents, or low-dose insulin therapy were included. Patients received DPP-4i alone (n = 144), DPP-4i plus basal insulin (n = 158) or basal-bolus regimen (n = 283). All groups received correctional doses with rapid-acting insulin for BG >140 mg/dL. The primary endpoint was differences in mean daily BG between groups. Secondary endpoints included differences in hypoglycemia and hospital complications.Results: There were no differences in mean hospital daily BG among patients treated with DPP-4i alone (170 ± 37 mg/dL), DPP-4i plus basal (172 ± 42 mg/dL), or basalbolus (172 ± 43 mg/dL), P = .94; or in the percentage of BG readings within target of 70 to 180 mg/dL (63 ± 32%, 60 ± 31%, and 64 ± 28%, respectively; P = .42). There were no differences in length of stay or complications, but hypoglycemia was less common with DPP-4i alone (2%) compared to DPP-4i plus basal (9%) and basal-bolus (10%); P = .004.Conclusion: Treatment with DPP-4i alone or in combination with basal insulin is effective and results in a lower incidence of hypoglycemia compared to a basal-bolus insulin regimen in general medicine and surgery patients with T2D.Abbreviations: BG = blood glucose; BMI = body mass index; CI = confidence interval; DPP-4i = dipeptidyl peptidase-4 inhibitors; HbA1c = hemoglobin A1c; OR = odds ratio; T2D = type 2 diabetes     

Design,synthesis and anti-diabetic activity of triazolotriazine derivatives as dipeptidyl peptidase-4 (DPP-4) inhibitors

Type 2 diabetes mellitus (T2DM) is one of the major global metabolic disorders characterized by insulin resistance and chronic hyperglycemia. Inhibition of the enzyme, dipeptidyl peptidase-4 (DPP-4) has been proved as successful and safe therapy for the treatment of T2DM since last decade. In order to design novel DPP-4 inhibitors, various in silico studies such as 3D-QSAR, pharmacophore modeling and virtual screening were performed and on the basis of the combined results of them, total 50 triazolo[5,1-c][1,2,4]triazine derivatives were designed and mapped on the best pharmacophore model. From this, best 25 derivatives were docked onto the active site of DPP-4 enzyme and in silico ADMET properties were also predicted. Finally, top 17 derivatives were synthesized and characterized using FT-IR, Mass, ¹H NMR and ¹³C NMR spectroscopy. Purity of compounds was checked using HPLC. These derivatives were then evaluated for in vitro DPP-4 inhibition. The most promising compound 15q showed 28.05 μM DPP-4 IC₅₀ with 8–10-fold selectivity over DPP-8 and DPP-9 so selected for further in vivo anti-diabetic evaluation. During OGTT in normal C57BL/6J mice, compound 15q reduced blood glucose excursion in a dose-dependent manner. Chronic treatment for 28 days with compound 15q improved the serum glucose levels in type 2 diabetic Sprague Dawley rats wherein diabetes was induced by high fat diet and low dose streptozotocin. This suggested that compound 15q is a moderately potent and selective hit molecule which can be further optimized structurally to increase the efficacy and overall pharmacological profile as DPP-4 inhibitor.     

Inhibition of Renal Glucose Reabsorption: A Novel Strategy for Achieving Glucose Control in Type 2 Diabetes Mellitus

ObjectiveTo review the renal handling of glucose and the role of inhibition of a sodium-glucose transporter (SGLT2) in the treatment of type 2 diabetes mellitus (T2DM).MethodsWe review the published data about (1) the filtration and reabsorption of glucose by the kidneys in normal subjects and patients with diabetes; (2) the deleterious effects of long-term elevation of plasma glucose levels on muscle and hepatic insulin sensitivity and beta cell function (that is, glucotoxicity); (3) the effect of inhibiting the SGLT2 transporter on the induction of glycosuria, glycemic control, insulin resistance, and beta cell dysfunction in animals and humans with diabetes; and (4) the safety of SGLT2 inhibition as a therapeutic modality to treat human T2DM.ResultsStudies in animal models of diabetes document the efficacy of the SGLT2 inhibitors in inducing glycosuria, decreasing both fasting and postprandial glucose levels, augmenting beta cell function, and enhancing hepatic and muscle insulin sensitivity. In human T2DM, short-term studies with dapagliflozin (12 weeks) and sergliflozin (2 weeks) have confirmed the efficacy of these agents in improving glycemic control. Excessive urinary electrolyte or water loss, plasma electrolyte disturbances, and hypoglycemia were not observed.ConclusionSGLT2 inhibitors represent a promising approach to the treatment of T2DM. They have the potential to be used as monotherapy, as well as in combination with all approved antidiabetic agents. Because their mechanism of action is independent of the severity of beta cell dysfunction or insulin resistance, efficacy should not decline with progressive beta cell failure or in the presence of severe insulin resistance. (Endocr Pract. 2008;14:782-790)     

Discovery of 3H-imidazo[4,5-c]quinolin-4(5H)-ones as potent and selective dipeptidyl peptidase IV (DPP-4) inhibitors

In recent years, dipeptidyl peptidase IV inhibitors have been noted as valuable agents for treatment of type 2 diabetes. Herein, we report the discovery of a novel potent DPP-4 inhibitor with 3H-imidazo[4,5-c]quinolin-4(5H)-one as skeleton. After efficient optimization of the lead compound 2a at the 7- and 8-positions using a docking study, we found 28 as a novel DPP-4 inhibitor with excellent selectivity against various DPP-4 homologues. Compound 28 showed strong DPP-4 inhibitory activity compared to marketed DPP-4 inhibitors. We also found that a carboxyl group at the 7-position could interact with the residue of Lys554 to form a salt bridge. Additionally, introduction of a carboxyl group to 7-position led to both activity enhancement and reduced risk for hERG channel inhibition and induced phospholipidosis. In our synthesis of compounds with 7-carboxyl group, we achieved efficient regioselective synthesis using bulky ester in the intramolecular palladium coupling reaction.     

The Emerging Role Of Adjunctive Noninsulin Antihyperglycemic Therapy In The Management Of Type 1 Diabetes

Objective: Review available data on adjunctive therapies for type 1 diabetes (T1D), with a special focus on newer antihyperglycemic agents.Methods: Published data on hypoglycemia, obesity, mortality, and goal attainment in T1D were reviewed to determine unmet therapeutic needs. PubMed databases and abstracts from recent diabetes meetings were searched using the term “type 1 diabetes” and the available and investigational sodium-glucose cotransporter (SGLT) inhibitors, glucagon-like peptide 1 (GLP-1) receptor agonists, dipeptidyl peptidase 4 inhibitors, and metformin.Results: The majority of patients with T1D do not meet glycated hemoglobin (A1C) goals established by major diabetes organizations. Hypoglycemia risks and a rising incidence of obesity and metabolic syndrome featured in the T1D population limit optimal use of intensive insulin therapy. Noninsulin antihyperglycemic agents may enable T1D patients to achieve target A1C levels using lower insulin doses, which may reduce the risk of hypoglycemia. In pilot studies, the SGLT2 inhibitor dapagliflozin and the GLP-1 receptor agonist liraglutide reduced blood glucose, weight, and insulin dose in patients with T1D. Phase 2 studies with the SGLT2 inhibitor empagliflozin and the dual SGLT1 and SGLT2 inhibitor sotagliflozin, which acts in the gut and the kidney, have demonstrated reductions in A1C, weight, and glucose variability without an increased incidence of hypoglycemia.Conclusion: Newer antihyperglycemic agents, particularly GLP-1 agonists, SGLT2 inhibitors, and dual SGLT1 and SGLT2 inhibitors, show promise as adjunctive treatment for T1D that may help patients achieve better glucose control without weight gain or increased hypoglycemia.Abbreviations:A1C = glycated hemoglobinBMI = body mass indexCI = confidence intervalDKA = diabetic ketoacidosisDPP-4 = dipeptidyl peptidase 4GLP-1 = glucagonlike peptide 1PYY = polypeptide tyrosine tyrosineSGLT = sodium-glucose cotransporterSGLT1 = sodium-glucose cotransporter 1SGLT2 = sodium-glucose cotransporter 2T1D = type 1 diabetesT2D = type 2 diabetesTDD = total daily dosage     

Sitagliptin in Glutamic Acid Decarboxylase Antibody-Positive Diabetes Mellitus

ObjectiveTo describe a case illustrating the use of sitagliptin, an inhibitor of dipeptidyl-peptidase-4 (DPP-4), in anti-glutamic acid decarboxylase antibody-positive diabetes mellitus in association with a rare ataxic variant of stiff person syndrome.MethodsWe present our experience with use of the DPP-4 inhibitor sitagliptin for management of autoimmune diabetes in a elderly woman and highlight the association of diabetes with other autoimmune conditions.ResultsA 68-year-old Japanese woman presented with poorly controlled “type 2” diabetes mellitus, cerebral palsy, cerebellar ataxia, and hypothyroidism. She complained of stiffness and spasms, which had resulted in multiple falls and immobility. Antidiabetic medications included gliclazide, rosiglitazone, and acarbose; various insulins had been tried but discontinued because they worsened her stiffness and spasms. Her hemoglobin A_1c values remained above 9% despite maximal doses of the aforementioned orally administered hypoglycemic agents. After sitagliptin therapy was initiated, her hemoglobin A_1c level decreased from 9.3% (78 mmol/mol) to 7.3% (56 mmol/mol) in 5 months. Investigations confirmed the presence of an ataxic variant of stiff person syndrome. On repeated testing 18 months later, her anti-glutamic acid decarboxylase antibody levels had declined by more than 85%.ConclusionApart from the well-known mechanism of an increase in glucagonlike peptide-1, sitagliptin may exert its glucose-lowering effect by other mechanisms in patients with autoimmune diabetes. Further studies should be undertaken to address the effectiveness of DPP-4 inhibitors in non-type 2 diabetes. (Endocr Pract. 2012;18: e65-e68)     

Decreased Mortality After Long-Term Treatment With Dipeptidyl Peptidase-4 Inhibitors: A Retrospective Study of U.S. Veterans With Type 2 Diabetes

ObjectiveThe prevalence of chronic kidney disease (CKD) in the United States is 13% of the general population. Among those with CKD, diabetic nephropathy is the leading cause of end-stage renal disease. This is a retrospective study examining the effect of long-term use of dipeptidyl peptidase-4 (DPP-4) inhibitors on all-cause mortality and progression of renal disease in the veteran population.MethodsData was extracted using the Veterans Administration Informatics and Computing Infrastructure. A large cohort of veterans diagnosed with type 2 diabetes mellitus were used to identify patients on DPP-4 inhibitors and without DPP-4 inhibitors. Groups were compared to determine the effect of DPP-4 inhibitors on the progression of CKD and all-cause mortality. Data were analyzed using SAS.ResultsSubjects in the treatment group (n = 40 558) had baseline variables (age, body mass index, race) similar to the control group (n = 40 558). Diabetes control improved in the treatment group (HgbA1c, 8.3% [67 mmol/mol] to 7.8% [62 mmol/mol]; P < .001) but not in the control group (HgbA1c, 7.4% [57 mmol/mol] to 7.3% [56 mmol/mol]). New diagnoses of heart failure and coronary artery bypass grafts were clinically significant (odds ratios = 0.66 and 0.52). No change in progression of CKD was seen in either group. All-cause mortality was reduced by 59%.ConclusionWe conclude that DPP-4 inhibitors are associated with a significant reduction in all-cause mortality independent of glucose control, albeit with no clear cause, including obtainable cardiovascular outcomes. Our data is consistent with prior trials in that DPP-4 inhibitors did not show a significant change in serum creatinine or microalbuminuria.     

Cardiovascular pleiotropic actions of DPP-4 inhibitors: A step at the cutting edge in understanding their additional therapeutic potentials

Dipeptidyl peptidase 4 (DPP-4) is a serine protease enzyme expressed widely in many tissues, including the cardiovascular system. The incretin hormones such as glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are released from the small intestine into the vasculature during a meal, and these incretins have a potential to release insulin from pancreatic beta cells of islets of Langerhans, affording a glucose-lowering action. However, both incretins are hurriedly degraded by the DPP-4. Inhibitors of DPP-4, therefore, enhance the bioavailability of GLP-1 and GIP, and thus have been approved for better glycemic management in patients afflicted with type 2 diabetes mellitus (T2DM). Five different DPP-4 inhibitors, often called as ‘gliptins’, namely sitagliptin, vildagliptin, saxagliptin, linagliptin and alogliptin have been approved hitherto for clinical use. These drugs are used along with diet and exercise to lower blood sugar in diabetic subjects. T2DM is intricately related with an increased risk of cardiovascular disease. Growing body of evidence suggests that gliptins, in addition to their persuasive anti-diabetic action, have a beneficial pleiotropic action on the heart and vessels. In view of the fact of cardiovascular disease susceptibility of patients afflicted with T2DM, gliptins might offer additional therapeutic benefits in treating diabetic cardiovascular complications. Exploring further the cardiovascular pleiotropic potentials of gliptins might open a panorama in impeccably employing these agents for the dual management of T2DM and T2DM-associated perilous cardiovascular complications. This review will shed lights on the newly identified beneficial pleiotropic actions of gliptins on the cardiovascular system.     

The Use of Premixed Insulin Analogues in the Treatment of Patients with Type 2 Diabetes Mellitus: Advantages and Limitations

Background:Intensive, target-oriented therapy is the standard of care in the management of patients with type 2 diabetesmellitus (DM). Early and aggressive use of insulin that is as close as possible to the physiologic pattern of insulin secretion from healthy pancreatic β-cells is advocated to achieve glycemic goals and reduce complications of DM.Objective:The objective of this article was to review the characteristics, advantages, and drawbacks of premixedinsulin analogues and to evaluate their role in the treatment of patients with type 2 DM.Methods:A PubMed search of articles from 1990 to 2006 was undertaken using the search terms type 2 diabetes, basalbolus therapy, premixed insulins, biphasic insulins, and insulin analogues. Pertinent content from relevant articles was extracted and combined with the authors' knowledge, experience, and clinical expertise.Results:The advent of insulin analogues has streamlined the treatment of patients with DM. When to initiate insulin during the course of treatment is the subject of much debate. Insulin therapy targeting both fasting and postprandial hyperglycemia is important in achieving optimal blood glucose (BG) control in patients with type 2 DM. A practical and feasible option is the use of >1 injection of premixed insulin analogues. Premixed insulin preparations provide both basal and prandial coverage because of their biphasic pharmacokinetic properties. Clinical trials have shown that these agents improve glycemic control, are associated with an acceptably low rate of severe hypoglycemia, and have a high degree of patient acceptance. Limitations include the inability to adjust the long- and short-acting components separately, to use a flexible regimen of self-titration and premeal bolus-insulin calculations, and to adequately treat postlunch and earlymorning BG elevations.Conclusion:Clinicians should be aware of premixed insulin analogues' advantages and limitations so that these agentscan be used appropriately in the treatment of patients with type 2 DM.     

The role of rapid-acting insulin analogues and inhaled insulin in type 2 diabetes mellitus

sBackground:The availability of rapid-acting insulin analogues and inhaled insulin gives clinicians additional treatmentoptions in the management of patients with diabetes mellitus (DM). Combining rapid-acting insulin analogues with basal insulin can more closely mimic physiologic insulin release to maximize glycemic control.Objective:The objective of this article was to discuss the role of rapid-acting insulin analogues and inhaled insulin inthe treatment of patients with type 2 DM.Methods:Materials for this article were obtained through an online search of MEDLINE/PubMed and Google(1996-2006) using the search terms bolus insulin, postprandial, rapid-acting insulin analogues, titration, hypoglycemia, glycemic control, inhaled insulin, and insulins lispro, aspart, and glulisine.Results:Glycosylated hemoglobin (A1C) levels and number of all hypoglycemic episodes were similar in patients withtype 2 DM taking either mealtime rapid-acting insulin analogues or regular human insulin (RHI). Rapid-acting insulins have been successfully used in basal-bolus regimens with a variety of long- and intermediate-acting insulins, as well as with oral hypoglycemic agents. Injectable rapid-acting insulin analogues markedly decreased postprandial glucose (PPG) levels compared with RHI. Better reduction in PPG levels may be key to achieving target A1C levels in some patients, but long-term outcome studies are needed to assess whether lowering PPG levels decreases cardiovascular risk in patients with type 2 DM. Inhaled insulin may be an option for patients who cannot inject insulin, but route of administration and dosing issues limit its use in many patients. The effect of inhaled insulin on PPG is unclear at this time.Conclusions:Although rapid-acting insulin analogues are effective in the management of patients with type 2 DM, the limited numbers of studies have yet to demonstrate that these agents have any significant long-term advantage compared with RHI. In addition, they cost more than RHI. Further studies are needed to compare the efficacy of the rapid-acting insulin analogues, to compare the different dosing regimens used with mealtime insulin administration, and to ascertain if the decrease in PPG levels seen with the use of rapid-acting insulin analogues translates into improved glycemic control and perhaps even a reduction in cardiovascular risk in patients with type 2 DM. (Insulin. 2007;2:61-67) Copyright 2007 Excerpta Medica, Inc.     

Synthesis,nitric oxide release,and dipeptidyl peptidase-4 inhibition of sitagliptin derivatives as new multifunctional antidiabetic agents

Nitric oxide (NO) dysfunction has been found to be an important factor in both the development and progression of diabetic complications due to its many roles in the vascular system. Multifunctional compounds with hypoglycemic and endothelial protective action will be promising agents for the treatment of diabetes and its complications. In this study, a series of novel NO-donating sitagliptin derivatives and relevant metabolites were synthesized and evaluated as potential multifunctional hypoglycemic agents. All of synthetic compounds shown remarkable inhibitory activity against dipeptidyl peptidase IV (DPP-IV) in vitro and demonstrated excellent hypoglycemic activities in diabetic mice, similar to the activity of sitagliptin, and compounds T1-T4 shown different extents of NO-releasing abilities and potent antioxidant abilities in vivo. By screening in DPP-4, compound T4 was recognized as a potent DPP-4 inhibitor with the IC₅₀ value of 0.060?μM. Docking study revealed compound T4 has a favorable binding mode. Furthermore, compounds T1-T4 exhibited different extents of NO-releasing abilities and excellent anti-platelet aggregation in vitro. The overall results suggested that T4 could help to the amelioration of endothelial dysfunction by reducing blood glucose, lessening oxidative stress and raising NO levels as well as inhibiting platelet aggregation. Based on this research, compound T4 deserves further investigation as potential new multifunctional anti-diabetic agent with antioxidant, anti-platelet aggregation and endothelial protective properties.     

Synthesis and biological evaluation of pyrrolidine-2-carbonitrile and 4-fluoropyrrolidine-2-carbonitrile derivatives as dipeptidyl peptidase-4 inhibitors for the treatment of type 2 diabetes

A novel series of pyrrolidine-2-carbonitrile and 4-fluoropyrrolidine-2-carbonitrile derivatives was designed, synthesized, and found to act as dipeptidyl peptidase-4 (DPP-4) inhibitors. From this series of compounds, compound 17a was identified as an efficacious, safe, and selective inhibitor of DPP-4. In vivo studies in ICR and KKAy mice showed that administration of this compound resulted in decreased blood glucose in these mice after an oral glucose challenge. Compound 17a showed high DPP-4 inhibitory activity (IC₅₀ = 0.017 μM), moderate selectivity against DPP-4 (selective ratio: DPP-8/DPP-4 = 1324; DPP-9/DPP-4 = 1164), and good efficacy in oral glucose tolerance tests in ICR and KKAy mice. These in vivo anti-diabetic properties and its desirable pharmacokinetic profile in Sprague–Dawley rats demonstrate that compound 17a is a promising candidate for development as an anti-diabetic agent.     

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

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