Incretin-based therapies

Efficacy and safety of sitagliptin with basal-plus insulin regimen versus insulin alone in non-critically ill hospitalized patients with type 2 diabetes: SITA-PLUS hospital trial

AIMS

To compare the efficacy and safety of basal-plus (BP) insulin regimen with or without sitagliptin in non-critically ill patients with type 2 diabetes (T2D).

METHODS

This open-label, randomized clinical trial included inpatients with a previous diagnosis of T2D and blood glucose (BG) between 180 and 400 mg/dL. Participants received basal and correctional insulin doses (BP regimen) either with or without sitagliptin. The primary outcome was the difference in the mean daily BG among the groups.

RESULTS

Seventy-six patients (mean age 60 years, 64 % men) were randomized. Compared with BP insulin therapy alone, the sitagliptin-BP combination led to a lower mean daily BG (158.8 vs 175.0 mg/dL, P = 0.014), a higher percentage of readings within a BG range of 70-180 mg/dL (75.9 % vs 64.7 %, P < 0.001), and a lower number of BG readings >180 mg/dL (P < 0.001). Sitagliptin-BP resulted in fewer basal and supplementary insulin doses (P = 0.024 and P = 0.017, respectively) and lower daily insulin injections (P = 0.023) than those with insulin alone. The proportion of patients with hypoglycemia was similar in the two groups.

CONCLUSIONS

For inpatients with T2D and hyperglycemia, the sitagliptin and BP regimen combination is safe and more effective than insulin therapy alone.

CLINICALTRIALS

gov identifier: NCT05579119.

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

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

Current Weight Loss Medications: What Plastic Surgeons Should Know

The World Health Organization (WHO) estimates that over 650 million adults are obese worldwide. Recently, antidiabetic medications have rapidly become popular as weight loss medications. With the rising prevalence of obesity and the increasing demand for aesthetic procedures, it is anticipated that a growing number of patients presenting for consultation will be prescribed these medications. Therefore, it is critical for practicing plastic surgeons to understand their potential synergistic effects and safety considerations. This manuscript explores the potential benefits and considerations of antidiabetic medications in plastic surgery patients for weight loss therapy. The authors discuss the mechanisms of action, clinical efficacy, potential side effects, and relevant considerations for incorporating these medications into plastic surgery practices and medical spas.

The Benefit of Healthy Lifestyle in the Era of New Medications to Treat Obesity

Incretin-based medications for treating obesity produce substantial short- and long-term weight loss and improve obesity-related comorbidities. However, associating lifestyle modification with new medications to treat obesity is generally advisable for several reasons. Firstly, healthy eating patterns and physical activity may offer important additional benefits, enhancing the patient's health and well-being. In addition, regular specialist counselling in lifestyle modification can help patients maintain their motivation levels and develop specific skills for addressing obstacles during the lengthy process of weight loss and maintenance, potentially improving outcomes in the long term. Given the high efficacy of the new weight-loss drugs, it would be timely to streamline and simplify the current gold standard of obesity management based on lifestyle modification. For example, it now seems redundant to prescribe strict diets or meal replacements to reduce calorie intake, or to recommend patients practice 200 to 300 minutes of moderate-to-vigorous-intensity exercise for enhanced weight loss. Moderate calorie restriction and, at least 150 minutes of moderate-intensity aerobic exercise and two sessions of muscle-strengthening activities per week may be more achievable and appropriate goals for sustainable weight loss in most patients on pharmaceutical obesity treatment. As regards lifestyle modification counselling, future studies should assess its optimal intensity and duration in the "new medications for obesity era".

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

CONCLUSION

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

An olive-derived elenolic acid stimulates hormone release from L-cells and exerts potent beneficial metabolic effects in obese diabetic mice

Insulin resistance and progressive decline in functional β-cell mass are two key factors for developing type 2 diabetes (T2D), which is largely driven by overweight and obesity, a significant obstacle for effective metabolic control in many patients with T2D. Thus, agents that simultaneously ameliorate obesity and act on multiple pathophysiological components could be more effective for treating T2D. Here, we report that elenolic acid (EA), a phytochemical, is such a dual-action agent. we show that EA dose-dependently stimulates GLP-1 secretion in mouse clonal L-cells and isolated mouse ileum crypts. In addition, EA induces L-cells to secrete peptide YY (PYY). EA induces a rapid increase in intracellular [Ca²⁺]_i and the production of inositol trisphosphate in L-cells, indicating that EA activates phospholipase C (PLC)-mediated signaling. Consistently, inhibition of (PLC) or Gα_q ablates EA-stimulated increase of [Ca²⁺]_i and GLP-1 secretion. In vivo, a single dose of EA acutely stimulates GLP-1 and PYY secretion in mice, accompanied with an improved glucose tolerance and insulin levels. Oral administration of EA at a dose of 50 mg/kg/day for 2 weeks normalized the fasting blood glucose and restored glucose tolerance in high-fat diet-induced obese (DIO) mice to levels that were comparable to chow-fed mice. In addition, EA suppresses appetite, reduces food intake, promotes weight loss, and reverses perturbated metabolic variables in obese mice. These results suggest that EA could be a dual-action agent as an alternative or adjuvant treatment for both T2D and obesity.

Evidence-based therapeutics for hyperglycemia in hospitalized noncritically ill patients

Hyperglycemia in hospitalized patients, either with or without diabetes, is a common, serious, and costly healthcare problem. Evidence accumulated over 20 years has associated hyperglycemia with a significant increase in morbidity and mortality, both in surgical and medical patients. Based on this documented link between hyperglycemia and poor outcomes, clinical guidelines from professional organizations recommend the treatment of hospital hyperglycemia with a therapeutic goal of maintaining blood glucose (BG) levels less than 180 mg/dL. Insulin therapy remains a mainstay of glycemic management in the inpatient setting. The use of non-insulin antidiabetic drugs in the hospital setting is limited because little data are available regarding their safety and efficacy. However, information about the use of incretin-based therapy in inpatients has increased in the past 15 years. This review aims to summarize the different treatment strategies for hyperglycemia in hospitalized noncritical patients that are supported by observational studies or clinical trials with insulin and non-insulin drugs. In addition, we propose a protocol to help with the management of this important clinical problem.

Management of Hyperglycemia in Older Adults with Type 2 Diabetes

The increasing incidence of type 2 diabetes in the general population as well as enhanced life expectancy has resulted in a rapid rise in the prevalence of diabetes in the older population. Diabetes causes significant morbidity and impairs quality of life. Managing diabetes in older adults is a daunting task due to unique health and psychosocial challenges. Medical management is complicated by polypharmacy, cognitive impairment, urinary incontinence, injurious falls, and persistent pain. Health care providers now have several traditional and contemporary pharmacologic agents to manage diabetes. Avoidance of hypoglycemia is critical; however, evidence-based guidelines are lacking due to the paucity of clinical trials in older adults. For many in this population, maintaining independence is more important than adherence to published guidelines to prevent diabetes complications. The goal of diabetes care in older adults is to enhance the quality of life without subjecting these patients to intrusive and complicated interventions. Recent technological advancements such as continuous glucose monitoring systems can have crucial supplementary benefits in the geriatric population.

Incretin-based therapy for glycemic control of hospitalized patients with type 2 diabetes: a systematic review

Incretin-based therapy leads to glycemic control in a glucose-dependent manner with a low risk of hypoglycemia, making it appealing for use in the hospital. The aim of this systematic review was to assess the benefits of incretin-based therapy in patients with type 2 diabetes hospitalized outside of the intensive care unit. We searched for studies published up to August 2021 in the PubMed and Scopus databases. Clinical trials comparing incretin-based therapy (alone or in combination with insulin) versus an insulin regimen were selected. The results of the included studies showed that incretin-based therapy showed mean blood glucose values, a percentage of records within the therapeutic target, and a percentage of treatment failure similar to insulin management, particularly in patients with mild to moderate hyperglycemia. Furthermore, incretin-based treatment was associated with a lower total insulin dose and a lower incidence of hypoglycemia. In conclusion, incretin-based therapy achieved glycemic control similar to insulin treatment in patients with type 2 diabetes hospitalized outside the intensive care unit and has the advantages of reducing the insulin requirement and a lower risk of hypoglycemia.

Small-molecule GLP-1 secretagogs: challenges and recent advances

Glucagon-like peptide-1 (GLP-1) is a potent anti-hyperglycemic hormone that is an alternative treatment choice for patients with type 2 diabetes mellitus (T2DM). The glucose-dependent mechanism of GLP-1 is particularly important because it does not stimulate insulin secretion and cause hypoglycemia when plasma glucose concentrations are in the normal fasting range. Although several peptide drugs of GLP-1 analogs are clinically available, research on the small molecules that stimulate GLP-1 secretion is still struggling. In this review, we summarize recent updates in the discovery of small-molecule GLP-1 secretagogs targeting the G-protein-coupled receptor (GPCR) family. We also discuss the challenges and strategies for the study and describe the latest developments.

Regenerative medicine of pancreatic islets

The pancreas became one of the first objects of regenerative medicine, since other possibilities of dealing with the pancreatic endocrine insufficiency were clearly exhausted. The number of people living with diabetes mellitus is currently approaching half a billion, hence the crucial relevance of new methods to stimulate regeneration of the insulin-secreting β-cells of the islets of Langerhans. Natural restrictions on the islet regeneration are very tight; nevertheless, the islets are capable of physiological regeneration via β-cell self-replication, direct differentiation of multipotent progenitor cells and spontaneous α- to β- or δ- to β-cell conversion (trans-differentiation). The existing preclinical models of β-cell dysfunction or ablation (induced surgically, chemically or genetically) have significantly expanded our understanding of reparative regeneration of the islets and possible ways of its stimulation. The ultimate goal, sufficient level of functional activity of β-cells or their substitutes can be achieved by two prospective broad strategies: β-cell replacement and β-cell regeneration. The “regeneration” strategy aims to maintain a preserved population of β-cells through in situ exposure to biologically active substances that improve β-cell survival, replication and insulin secretion, or to evoke the intrinsic adaptive mechanisms triggering the spontaneous non-β- to β-cell conversion. The “replacement” strategy implies transplantation of β-cells (as non-disintegrated pancreatic material or isolated donor islets) or β-like cells obtained ex vivo from progenitors or mature somatic cells (for example, hepatocytes or α-cells) under the action of small-molecule inducers or by genetic modification. We believe that the huge volume of experimental and clinical studies will finally allow a safe and effective solution to a seemingly simple goal-restoration of the functionally active β-cells, the innermost hope of millions of people globally.

Flavone Hispidulin Stimulates Glucagon-Like Peptide-1 Secretion and Ameliorates Hyperglycemia in Streptozotocin-Induced Diabetic Mice

SCOPE

Loss of functional β-cell mass is central for the deterioration of glycemic control in diabetes. The incretin hormone glucagon-like peptide-1 (GLP-1) plays a critical role in maintaining glycemic homeostasis via potentiating glucose-stimulated insulin secretion and promoting β-cell mass. Agents that can directly promote GLP-1 secretion, thereby increasing insulin secretion and preserving β-cell mass, hold great potential for the treatment of T2D.

METHODS AND RESULTS

GluTag L-cells, INS832/13 cells, and mouse ileum crypts and islets are cultured for examining the effects of flavone hispidulin on GLP-1 and insulin secretion. Mouse livers and isolated hepatocytes are used for gluconeogenesis. Streptozotocin-induced diabetic mice are treated with hispidulin (20 mg kg^-1 day^-1 , oral gavage) for 6 weeks to evaluate its anti-diabetic potential. Hispidulin stimulates GLP-1 secretion from the L-cell line, ileum crypts, and in vivo. This hispidulin action is mediated via activation of cyclic adenosine monophosphate/protein kinase A signaling. Hispidulin significantly improves glycemic control in diabetic mice, concomitant with improved insulin release, and β-cell survival. Additionally, hispidulin decreases hepatic pyruvate carboxylase expression in diabetic mice and suppresses gluconeogenesis in hepatocytes. Furthermore, hispidulin stimulates insulin secretion from β-cells.

CONCLUSION

These findings suggest that Hispidulin may be a novel dual-action anti-diabetic compound via stimulating GLP-1 secretion and suppressing hepatic glucose production.

Dulaglutide-combined basal plus correction insulin therapy contributes to ideal glycemic control in non-critical hospitalized patients

AIMS/INTRODUCTION

We investigated whether dulaglutide (DU)-combined conventional insulin therapy is beneficial for glycemic control in non-critically ill hospitalized patients with type 2 diabetes.

MATERIALS AND METHODS

This study was a prospective, randomized controlled pilot study. Participants were randomized to either basal-plus (BP) therapy, where basal insulin and corrective doses of regular insulin were administered before meals, or BP + DU therapy, where BP therapy was combined with DU. Blood glucose (BG) levels before and after every meal were measured for 7 days after assignment to groups. Because we consider the ideal BG during hospitalization to be within 100-180 mg/dL, we defined this range as the hospitalized ideal glucose range (hIGR). We compared the percentage of BG measurements within the hIGR among all BG measurements (%hIGR), mean BG, glucose variability and insulin dose between the two groups.

RESULTS

Of 54 patients, 27 were assigned to the BP group and 27 to the BP + DU group. The %hIGR was significantly higher (44% vs 56%, P < 0.001), and the frequency of BG >240 mg/dL and BG <70 mg/dL was significantly lower in the BP + DU group than in the BP group (both P < 0.001). The mean BG (183 ± 29 vs 162 ± 30 mg/dL, P < 0.05), standard deviation (P < 0.01), coefficient of variation (P < 0.01) and total regular insulin dose (P < 0.05) in the BP + DU group were significantly lower than those in the BP group. No significant side-effects were observed in either group.

CONCLUSIONS

BP + DU therapy reduced the frequency of hyperglycemia and hypoglycemia, and resulted in a lower glucose variability.

A Human Glucagon-Like Peptide-1-albumin Recombinant Protein with Prolonged Hypoglycemic Effect Provides Efficient and Beneficial Control of Glucose Metabolism in Diabetic Mice

GW002 is a recombinant protein engineered by fusing the C-terminal region of human glucagon-like peptide-1 (GLP-1) to the N-terminal region of human serum albumin (HSA) with a peptide linker. This study aims to evaluate its anti-diabetic effects both in vitro and in vivo. The GLP-1 receptor-dependent luciferase reporter plasmid was transiently transfected in NIT-1 cells to calculate the half-maximal concentration (EC₅₀) for GLP-1 receptor activation, and normal ICR mice and diabetic KKAy mice were acutely injected with GW002 (1, 3, 9 mg/kg) subcutaneously to evaluate the hypoglycemic action, while the diabetic KKAy and db/db mice were treated with GW002 once daily for 7 weeks to evaluate the effects on glucose metabolism. The results showed that GW002 activated GLP-1 receptor in NIT-1 cells with higher EC₅₀ versus exendin-4 (46.7 vs. 7.89 nM), and single subcutaneous injection of GW002 at doses of 1, 3 and 9 mg/kg efficiently restrained the glycemia variation after oral glucose loading in ICR mice for at least 4 d, as well as reducing the non-fasting blood glucose in KKAy mice for about 2 d, while repeated injections of GW002 significantly improved abnormal glycaemia, hemoglobin (Hb)A1c levels, oral glucose intolerance and β-cell function in diabetic db/db mice. These results suggested that GW002 showed prolonged hypoglycemic action by activating its cognate receptor and provided efficient control of glucose metabolism. Thus GW002 may be a potential treatment for the management of type 2 diabetes.

Treatment Outcomes and Tolerability Following Initiation of GLP-1 Receptor Agonists Among Type 2 Diabetes Patients in Primary Care Practices in Germany

BACKGROUND

The aim was to investigate real-world treatment outcomes and tolerability of GLP-1 receptor agonist (GLP-1RA) therapy in patients with type 2 diabetes in Germany.

METHODS

Patients from 323 primary care practices who started any GLP-1RA therapy (89 Byetta, 108 Bydureon, 347 Victoza patients) between January 1, 2011, and December 31, 2013 (index date) were analyzed retrospectively (Disease Analyzer database, Germany). Changes from baseline in HbA1c, weight, and hypoglycemia were evaluated in 3 follow-up periods of 0-6, 7-12, and 13-18 months.

RESULTS

A total of 544 diabetes patients (mean age: 57.9 years; men: 54%) were eligible for the study. Mean (SD) HbA1c (%) decreased from 8.3 (1.4) at baseline to 7.4 (1.2) in 6 months, 7.6 (1.3) in 7-12 months and 7.6 (1.4) in 13-18 months, respectively ( P < .001 for all), while the proportion of patients with HbA1c <7% increased from 15% at baseline to 38%, 36% and 35% in the corresponding periods ( P < .0001 for all). Multivariate-adjusted beta coefficients corresponding to changes in HbA1c (%) from baseline were -.52, -.44, and -.44, respectively, in the follow-up periods for baseline HbA1c (%) ( P < .0001 for all). The prevalence of hypoglycemia at baseline was 0.7%; this did not change significantly after treatment.

CONCLUSIONS

In clinical practice, GLP-1RA treatment was associated with improved glycemic control without increased hypoglycemia for up to 18 months. The higher the baseline HbA1c, the greater the HbA1c reduction recorded.

The Potential Therapeutic Application of Peptides and Peptidomimetics in Cardiovascular Disease

Cardiovascular disease (CVD) remains a leading cause of mortality and morbidity worldwide. Numerous therapies are currently under investigation to improve pathological cardiovascular complications, but yet, there have been very few new medications approved for intervention/treatment. Therefore, new approaches to treat CVD are urgently required. Attempts to prevent vascular complications usually involve amelioration of contributing risk factors and underlying processes such as inflammation, obesity, hyperglycaemia, or hypercholesterolemia. Historically, the development of peptides as therapeutic agents has been avoided by the Pharmaceutical industry due to their low stability, size, rate of degradation, and poor delivery. However, more recently, resurgence has taken place in developing peptides and their mimetics for therapeutic intervention. As a result, increased attention has been placed upon using peptides that mimic the function of mediators involved in pathologic processes during vascular damage. This review will provide an overview on novel targets and experimental therapeutic approaches based on peptidomimetics for modulation in CVD. We aim to specifically examine apolipoprotein A-I (apoA-I) and apoE mimetic peptides and their role in cholesterol transport during atherosclerosis, suppressors of cytokine signaling (SOCS)1-derived peptides and annexin-A1 as potent inhibitors of inflammation, incretin mimetics and their function in glucose-insulin tolerance, among others. With improvements in technology and synthesis platforms the future looks promising for the development of novel peptides and mimetics for therapeutic use. However, within the area of CVD much more work is required to identify and improve our understanding of peptide structure, interaction, and function in order to select the best targets to take forward for treatment.

Obesity and diabetes: An update

The twin epidemic of obesity and diabetes is a major crisis globally. Several epidemiologic studies reveal the parallel escalation of obesity and diabetes. The term 'diabesity' expresses their close relationship to each other, wherein both these metabolic disorders are characterized by defects of insulin action. The pathophysiology connecting obesity and diabetes is chiefly attributed to two factors: insulin resistance and insulin deficiency. Recent years have seen an increasing body of work on the following metabolic defects common to both obesity and diabetes such as, impaired tissue perfusion, sleep disturbances, androgen dysfunction, altered Vitamin D levels and GI stress. The scope of this review is to present the most widely accepted theories that link the two diseases, provide an update on some proposed unifying metabolic defects and highlight current and future prevention and management strategies.

Novel Anti-glycemic Drugs and Reduction of Cardiovascular Risk in Diabetes: Expectations Realized, Promises Unmet

PURPOSE OF REVIEW

The purpose is to review evidence on cardiovascular risks and benefits of new treatments for type 2 diabetes mellitus.

RECENT FINDINGS

In response to guidance issued by the Food and Drug Administration, thousands of patients have been enrolled in large randomized trials evaluating the cardiovascular effects of the three newest diabetes drug classes: glucagon-like peptide-1 (GLP-1) receptor agonists, sodium glucose cotransporter 2 (SGLT-2) inhibitors, and dipeptidyl peptidase-4 (DPP-4) inhibitors. Two studies of GLP-1 receptor agonists-one of liraglutide and one of semaglutide-have shown cardiovascular benefit relative to placebo, and one study of the SGLT-2 inhibitor empagliflozin has shown benefit. The other published cardiovascular outcome studies of the newest drug classes have generally supported safety, apart from an as-yet unresolved safety concern about increased rates of heart failure with DPP-4 inhibitors. Recent research suggests the thiazolidinedione pioglitazone may have beneficial effects on some cardiovascular outcomes as well, but these are counterbalanced by a known increase of the risk of heart failure with this drug. In general, more prospective randomized trial data is now available regarding the cardiovascular effects of the newer diabetes drugs than on the older drug classes. New evidence suggests that the newest diabetes drugs are safe from a cardiovascular perspective. Evidence on benefit from at least some members of the GLP-1 receptor agonist and SGLT-2 inhibitor classes is encouraging but not yet decisive.

Heterologous Expression and Delivery of Biologically Active Exendin-4 by Lactobacillus paracasei L14

Exendin-4, a glucagon-like protein-1 (GLP-1) receptor agonist, is an excellent therapeutic peptide drug for type 2 diabetes due to longer lasting biological activity compared to GLP-1. This study explored the feasibility of using probiotic Lactobacillus paracasei as an oral vector for recombinant exendin-4 peptide delivery, an alternative to costly chemical synthesis and inconvenient administration by injection. L. paracasei transformed with a plasmid encoding the exendin-4 gene (L. paracasei L14/pMG76e-exendin-4) with a constitutive promotor was successfully constructed and showed efficient secretion of exendin-4. The secreted exendin-4 significantly enhanced insulin secretion of INS-1 β-cells, along with an increment in their proliferation and inhibition of their apoptosis, corresponding to the effect of GLP-1 on these cells. The transcription level of the pancreatic duodenal homeobox-1 gene (PDX-1), a key transcription factor for cellular insulin synthesis and secretion, was upregulated by the treatment with secreted exendin-4, paralleling the upregulation of insulin gene expression. Caco-2 cell monolayer permeability assay showed a 34-fold increase in the transport of exendin-4 delivered by L. paracasei vs. that of free exendin-4 (control), suggesting effective facilitation of exendin-4 transport across the intestinal barrier by this delivery system. This study demonstrates that the probiotic Lactobacillus can be engineered to secrete bioactive exendin-4 and facilitate its transport through the intestinal barrier, providing a novel strategy for oral exendin-4 delivery using this lactic acid bacterium.

Cardiovascular Effects of Incretin-Based Therapies

The incretin-based therapies, dipeptidyl peptidase-4 (DPP4) inhibitors and glucagon-like peptide-1 (GLP-1) analogs, are important new classes of therapy for type 2 diabetes mellitus (T2DM). These agents prolong the action of the incretin hormones, GLP-1 and glucose-dependent insulinotropic polypeptide (GIP), by inhibiting their breakdown. The incretin hormones improve glycemic control in T2DM by increasing insulin secretion and suppressing glucagon levels. The cardiovascular (CV) effects of the incretin-based therapies have been of substantial interest since 2008, when the US Food and Drug Administration began to require that all new therapies for diabetes undergo rigorous assessment of CV safety through large-scale CV outcome trials. This article reviews the most recent CV outcome trials of the DPP-4 inhibitors (SAVOR-TIMI 53, EXAMINE, and TECOS) as evidence that the incretin-based therapies have acceptable CV safety profiles for patients with T2DM. The studies differ with regard to patient population, trial duration, and heart failure outcomes but show similar findings for CV death, nonfatal myocardial infarction, and stroke, as well as hospitalization for unstable angina.

Conformational Analysis of the Host-Defense Peptides Pseudhymenochirin-1Pb and -2Pa and Design of Analogues with Insulin-Releasing Activities and Reduced Toxicities

Pseudhymenochirin-1Pb (Ps-1Pb; IKIPSFFRNILKKVGKEAVSLIAGALKQS) and pseudhymenochirin-2Pa (Ps-2Pa; GIFPIFAKLLGKVIKVASSLISKGRTE) are amphibian peptides with broad spectrum antimicrobial activities and cytotoxicity against mammalian cells. In the membrane-mimetic solvent 50% (v/v) trifluoroethanol-H2O, both peptides adopt a well-defined α-helical conformation that extends over almost all the sequence and incorporates a flexible bend. Both peptides significantly (p < 0.05) stimulate the rate of release of insulin from BRIN-BD11 clonal β-cells at concentrations ≥ 0.1 nM but produce loss of integrity of the plasma membrane at concentrations ≥ 1 μM. Increasing cationicity by the substitution Glu(17) → l-Lys in Ps-1Pb and Glu(27) → l-Lys in Ps-2Pa generates analogues with increased cytotoxicity and reduced insulin-releasing potency. In contrast, the analogues [R8r]Ps-1Pb and [K8k,K19k]Ps-2Pa, incorporating d-amino acid residues to destabilize the α-helical domains, retain potent insulin-releasing activity but are nontoxic to BRIN-BD11 cells at concentrations of 3 μM. [R8r]Ps-1Pb produces a significant increase in insulin release rate at 0.3 nM and [K8k,K19k]Ps-2Pa at 0.01 nM. Both analogues show low hemolytic activity (IC50 > 100 μM) but retain broad-spectrum antimicrobial activity and remain cytotoxic to a range of human tumor cell lines, albeit with lower potency than the naturally occurring peptides. These analogues show potential for development into agents for type 2 diabetes therapy.

Advances in understanding relationship between GLP-1 based drugs and the kidney

The drugs based on glucagon-like peptide-1 (GLP-1) not only lower urinary protein, but also increase urine sodium excretion and improve the pathological changes of kidney disease. However, the mechanism is not very clear and may be associated with atrial natriuretic peptide, renin angiotensin axis, and oxidative stress. This review focuses on the progress in understanding the relationship between GLP-1 and the kidney.

DPP4 in Diabetes

Dipeptidyl-peptidase 4 (DPP4) is a glycoprotein of 110 kDa, which is ubiquitously expressed on the surface of a variety of cells. This exopeptidase selectively cleaves N-terminal dipeptides from a variety of substrates, including cytokines, growth factors, neuropeptides, and the incretin hormones. Expression of DPP4 is substantially dysregulated in a variety of disease states including inflammation, cancer, obesity, and diabetes. Since the incretin hormones, glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide (GIP), are major regulators of post-prandial insulin secretion, inhibition of DPP4 by the gliptin family of drugs has gained considerable interest for the therapy of type 2 diabetic patients. In this review, we summarize the current knowledge on the DPP4–incretin axis and evaluate most recent findings on DPP4 inhibitors. Furthermore, DPP4 as a type II transmembrane protein is also known to be cleaved from the cell membrane involving different metalloproteases in a cell-type-specific manner. Circulating, soluble DPP4 has been identified as a new adipokine, which exerts both para- and endocrine effects. Recently, a novel receptor for soluble DPP4 has been identified, and data are accumulating that the adipokine-related effects of DPP4 may play an important role in the pathogenesis of cardiovascular disease. Importantly, circulating DPP4 is augmented in obese and type 2 diabetic subjects, and it may represent a molecular link between obesity and vascular dysfunction. A critical evaluation of the impact of circulating DPP4 is presented, and the potential role of DPP4 inhibition at this level is also discussed.

The influence of age and metformin treatment status on reported gastrointestinal side effects with liraglutide treatment in type 2 diabetes

AIM

Treatment of type 2 diabetes with glucagon-like peptide-1 (GLP-1) receptor agonists may be limited by gastrointestinal side effects (GISE) in some patients. Risk factors for developing GISE are not known. We analysed patient characteristics that were associated with GISE among patients treated with the GLP-1 receptor agonist liraglutide.

METHODS

Data was obtained from an audit database of liraglutide use based in clinical practice in the UK. Patients were grouped into those who did not report GISE, those who reported GISE but continued liraglutide and those who discontinued liraglutide due to GISE within 26 weeks of treatment. Baseline variables of age, diabetes duration, HbA1c, weight, BMI, blood pressure, lipids, gender, ethnicity, alanine transaminotransferase, estimated glomerular filtration rate (eGFR) and diabetes treatment types were tested for possible associations with GISE outcome. Significant variables in univariate analyses were entered into ordinal logistic regression analyses.

RESULTS

A total of 4442 patients were suitable for analysis. A total of 3905 (87.9%) did not report GISE, 297 (6.7%) and 240 (5.4%) had GISE and continued and discontinued treatment, respectively. Age, weight, eGFR, metformin status and insulin status were associated with GISE outcome in univariate analyses (P all <0.05). In the final regression model, age (adjusted OR 1.15 [95%CI 1.05,1.26], P=0.002) and non-metformin use (adjusted OR 0.76 [95%CI 0.60,0.96], P=0.020) were associated with worse GISE outcome.

CONCLUSION

Older age and non-metformin use were associated with more significant GISE leading to discontinuation of liraglutide treatment. The reasons for these findings are unclear and warrant further investigation.