Management of Type 2 diabetes: the role of incretin mimetics

GLP-1 receptor agonists for the treatment of obesity: Role as a promising approach

Obesity is a complex disease characterized by excessive fat accumulation which is caused by genetic, environmental and other factors. In recent years, there has been an increase in the morbidity, disability rate,and mortality due to obesity, making it great threat to people's health and lives, and increasing public health care expenses. Evidence from previous studies show that weight loss can significantly reduce the risk of obesity-related complications and chronic diseases. Diet control, moderate exercise, behavior modification programs, bariatric surgery and prescription drug treatment are the major interventions used to help people lose weight. Among them, anti-obesity drugs have high compliance rates and cause noticeable short-term effects in reducing obese levels. However, given the safety or effectiveness concerns of anti-obesity drugs, many of the currently used drugs have limited clinical use. Glucagon-like peptide-1 receptor (GLP-1R) agonists are a group of drugs that targets incretin hormone action, and its receptors are widely distributed in nerves, islets, heart, lung, skin, and other organs. Several animal experiments and clinical trials have demonstrated that GLP-1R agonists are more effective in treating or preventing obesity. Therefore, GLP-1R agonists are promising agents for the treatment of obese individuals. This review describes evidence from previous research on the effects of GLP-1R agonists on obesity. We anticipate that this review will generate data that will help biomedical researchers or clinical workers develop obesity treatments based on GLP-1R agonists.

Gastrointestinal Incretins-Glucose-Dependent Insulinotropic Polypeptide (GIP) and Glucagon-like Peptide-1 (GLP-1) beyond Pleiotropic Physiological Effects Are Involved in Pathophysiology of Atherosclerosis and Coronary Artery Disease-State of the Art

Simple Summary

The presented manuscript contains the most current and extensive summary of the role of the most predominant gastrointestinal hormones—GIP and GLP-1 in the pathophysiology of atherosclerosis and coronary artery disease both in animals and humans. We have described GIP and GLP-1 as (1) expressed in many human tissues, (2) emphasized relationship between GIP and GLP-1 and inflammation, (3) highlighted importance of GIP and GLP-1-dependent pathways in atherosclerosis and coronary artery disease and (4) proved that GIP and GLP-1 could be used as markers of incidence, clinical course and recurrence of coronary artery disease, and related to extent and severity of atherosclerosis and myocardial ischemia. Our initial review may state a cornerstone for the future, however, there are still many unknowns and understatements on this topic. Due to the widespread growing interest for the potential use of incretins in cardiovascular diseases, we think that further research in this direction is desirable. For the future, we would like to recognize GIP and GLP-1 as widely implemented into clinical practice as new biomarkers of atherosclerosis and coronary artery disease.

Abstract

Coronary artery disease (CAD), which is the manifestation of atherosclerosis in coronary arteries, is the most common single cause of death and is responsible for disabilities of millions of people worldwide. Despite numerous dedicated clinical studies and an enormous effort to develop diagnostic and therapeutic methods, coronary atherosclerosis remains one of the most serious medical problems of the modern world. Hence, new markers are still being sought to identify and manage CAD optimally. Trying to face this problem, we have raised the question of the most predominant gastrointestinal hormones; glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), mainly involved in carbohydrates disorders, could be also used as new markers of incidence, clinical course, and recurrence of CAD and are related to extent and severity of atherosclerosis and myocardial ischemia. We describe GIP and GLP-1 as expressed in many animal and human tissues, known to be connected to inflammation and related to enormous noncardiac and cardiovascular (CV) diseases. In animals, GIP and GLP-1 improve endothelial function and lead to reduced atherosclerotic plaque macrophage infiltration and stabilize atherosclerotic lesions by directly blocking monocyte migration. Moreover, in humans, GIPR activation induces the pro-atherosclerotic factors ET-1 (endothelin-1) and OPN (osteopontin) but also has anti-atherosclerotic effects through secretion of NO (nitric oxide). Furthermore, four large clinical trials showed a significant reduction in composite of CV death, MI, and stroke in long-term follow-up using GLP-1 analogs for DM 2 patients: liraglutide in LEADER, semaglutide in SUSTAIN-6, dulaglutide in REWIND and albiglutide in HARMONY. However, very little is known about GIP metabolism in the acute phase of myocardial ischemia or for stable patients with CAD, which constitutes a direction for future research. This review aims to comprehensively discuss the impact of GIP and GLP-1 on atherosclerosis and CAD and its potential therapeutic implications.

Type-3c Diabetes Mellitus, Diabetes of Exocrine Pancreas - An Update

BACKGROUND

The incidence of diabetes is increasing steeply; the number of diabetics has doubled over the past three decades. Surprisingly, the knowledge of type 3c diabetes mellitus (T3cDM) is still unclear to the researchers, scientist and medical practitioners, leading towards erroneous diagnosis, which is sometimes misdiagnosed as type 1 diabetes mellitus (T1DM), or more frequently type 2 diabetes mellitus (T2DM). This review is aimed to outline recent information on the etiology, pathophysiology, diagnostic procedures, and therapeutic management of T3cDM patients.

METHODS

The literature related to T3cDM was thoroughly searched from the public domains and reviewed extensively to construct this article. Further, existing literature related to the other forms of diabetes is reviewed for projecting the differences among the different forms of diabetes. Detailed and updated information related to epidemiological evidence, risk factors, symptoms, diagnosis, pathogenesis and management is structured in this review.

RESULTS

T3cDM is often misdiagnosed as T2DM due to the insufficient knowledge differentiating between T2DM and T3cDM. The pathogenesis of T3cDM is explained which is often linked to the history of chronic pancreatitis, pancreatic cancer. Inflammation, and fibrosis in pancreatic tissue lead to damage both endocrine and exocrine functions, thus leading to insulin/glucagon insufficiency and pancreatic enzyme deficiency.

CONCLUSION

Future advancements should be accompanied by the establishment of a quick diagnostic tool through the understanding of potential biomarkers of the disease and newer treatments for better control of the diseased condition.

Efficacy and safety of once-weekly semaglutide for the treatment of type 2 diabetes

INTRODUCTION

Type 2 diabetes is a chronic metabolic disease characterized by persistent hyperglycemia resulting from progressive deficient of insulin in patients with a background of insulin resistance. Current treatment algorithms recommended by American Diabetes Association/The European Association for the Study of Diabetes promote a patient-centered approach that takes into account a comprehensive consideration of pharmacological properties of drugs, including glucose-lowering action, effects on body weight, correction on multiple pathophysiologic defects, tolerability, and long-term safety. Glucagon-likepeptide1 (GLP-1) receptor analogues are appealing due to the improved glycemic control in a glucose-dependent manner, modest weight loss and low risk of hypoglycemia. Areas covered: Semaglutide (Novo Nordisk), a once-weekly GLP-1 analogue, is currently in the phase III clinical trial for the treatment of type 2 diabetes. This article aims to review the pharmacological and clinical profiles of semaglutide based on the available clinical data. Expert opinion: Semaglutide achieved greater reduction from baseline in HbA_1c in comparison to placebo. The greater proportion of patients in semaglutide group than that in placebo group achieved target HbA_1c <7.0% and <6.5%, respectively. Semaglutide is the second GLP-1 analogue contributing to the reduced bodyweight and improving obesity related complications. More importantly, semaglutide is beneficial to diabetic patients with high cardiovascular risk according to the recently completed phase III trial. The incidence of gastrointestinal adverse effects increased with semaglutide dose.

New developments in insulin therapy for type 2 diabetes

Insulin has classically been considered a treatment of last resort for individuals with type 2 diabetes, delayed until all other efforts by the patient and healthcare provider have failed. Recent treatment guidelines recommend the use of insulin, in particular basal insulin, as part of a treatment regimen earlier in the disease process. Many patients are reticent about initiating insulin, so therapies that allow insulin treatment to be more tailored to individual needs are likely to result in greater acceptance and patient adherence with therapy. To meet this need, a range of insulin products are in development that aim to increase absorption rate or prolong the duration of action, reduce peak variability and weight gain associated with insulin treatment, and offer alternative delivery methods. This review describes insulin products in clinical development, new combination therapies, and new devices for insulin delivery.

Combination therapy with GLP-1 receptor agonists and basal insulin: a systematic review of the literature

Treatment algorithms for type 2 diabetes call for intensification of therapy over time as the disease progresses and glycaemic control worsens. If diet, exercise and oral antihyperglycaemic medications (OAMs) fail to maintain glycaemic control then basal insulin is added and ultimately prandial insulin may be required. However, such an intensification strategy carries risk of increased hypoglycaemia and weight gain, both of which are associated with worse long-term outcomes. An alternative strategy is to intensify therapy by the addition of a short-acting glucagon-like peptide-1 receptor agonist (GLP-1 RA) rather than prandial insulin. Short-acting GLP-1 RAs such as exenatide twice daily are particularly effective at reducing postprandial glucose while basal insulin has a greater effect on fasting glucose, providing a physiological rationale for this complementary approach. This review analyzes the latest randomized controlled clinical trials of insulin/GLP-1 RA combination therapy and examines results from 'real-world' use of the combinations as reported through observational and clinical practice studies. The most common finding across all types of studies was that combination therapy improved glycaemic control without weight gain or an increased risk of hypoglycaemia. Many studies reported weight loss and a reduction in insulin use when a GLP-1 RA was added to existing insulin therapy. Overall, the relative degree of benefit to glycaemic control and weight was influenced by the insulin titration employed in conjunction with the GLP-1 RA. The greatest glycaemic benefits were observed in studies with structured titration of insulin to glycaemic targets while the greatest weight benefits were observed in studies with a protocol-specified focus on insulin sparing. The adverse event profile of GLP-1 RAs in the reviewed trials was similar to that reported with GLP-1 RAs as monotherapy or in combination with OAMs with gastrointestinal events being the most commonly reported.

A randomized non-inferiority study comparing the addition of exenatide twice daily to sitagliptin or switching from sitagliptin to exenatide twice daily in patients with type 2 diabetes experiencing inadequate glycaemic control on metformin and sitagliptin

AIMS

To test the hypothesis that glycaemic control achieved when switching sitagliptin to exenatide twice daily plus metformin is non-inferior to adding exenatide twice daily to sitagliptin and metformin.

METHODS

Patients with Type 2 diabetes inadequately controlled with sitagliptin plus metformin were randomly assigned to 20 weeks of treatment with twice-daily exenatide plus placebo and metformin (SWITCH, n = 127) or twice-daily exenatide plus sitagliptin and metformin (ADD, n = 128).

RESULTS

Non-inferiority (0.4% margin) of SWITCH to ADD treatment, measured by change in HbA(1c) from baseline to week 20, was not shown {between-treatment difference in least-squares mean [95% CI 3 mmol/mol (0.30%)] [0.8-5.8 (0.07-0.53)]}. A greater reduction (P = 0.012) in HbA(1c) [least-squares mean (se)] was experienced by patients in the ADD group {-7 mmol/mol [-0.68%] [0.9 (0.08)]}, compared with those in the SWITCH group {-4 mmol/mol [-0.38%] [1.0 (0.09)]} and a greater proportion (P = 0.027) of patients in the ADD group (41.7%) reached < 7.0% (< 53 mmol/mol) HbA(1c) target, compared with those in the SWITCH group (26.6%) by week 20. Patients in the ADD group experienced greater fasting serum glucose (P = 0.038) and daily mean postprandial self-monitored blood glucose (P = 0.048) reductions, compared with patients in the SWITCH group, by week 20. Patients in both groups experienced a lower incidence of nausea and vomiting compared with previous exenatide studies.

CONCLUSIONS

Non-inferiority of SWITCH to ADD treatment was not supported by the results of this study. In patients with Type 2 diabetes inadequately controlled with sitagliptin plus metformin, adding exenatide provided better glycaemic control than switching to exenatide. These results are consistent with the clinical approach that adding is better than switching to another oral anti-hyperglycaemic medication.

Hypoglycemic Effect of Laminaria japonica Polysaccharide in a Type 2 Diabetes Mellitus Mouse Model

The aim is to investigate the hypoglycemic effect of Laminaria japonica polysaccharides (LJPS) on type 2 diabetes mellitus (T2DM) mice model. 60 healthy male mice have been used in the experiment. T2DM animal mode was prepared by high fatty forage feeding and intraperitoneal injection with alloxan. Diabetic mice were orally supplied with LJPS. Then their blood was collected for various biomedical measurements of fasting blood glucose (FBG), serum insulin, and amylin. Treatment with LJPS significantly reduced fasting blood glucose (P < 0.05) and increased the levels of insulin and amylin in serum (P < 0.05). Overall, the study presented that LJPS can reverse several components of T2DM. Therefore, LJPS may become a new oral candidate medicine for the treatment of diabetes.

SGLT2 inhibitors: molecular design and potential differences in effect

The physiological and pathological handling of glucose via sodium-glucose cotransporter-2 (SGLT2) in the kidneys has been evolving, and SGLT2 inhibitors have been focused upon as a novel drug for treating diabetes. SGLT2 inhibitors enhance renal glucose excretion by inhibiting renal glucose reabsorption. Consequently, SGLT2 inhibitors reduce plasma glucose insulin independently and improve insulin resistance in diabetes. To date, various SGLT2 inhibitors have been developed and evaluated in clinical studies. The potency and positioning of SGLT2 inhibitors as an antidiabetic drug are dependent on their characteristic profile, which induces selectivity, efficacy, pharmacokinetics, and safety. This profile decides which SGLT2 inhibitors can be expected for application of the theoretical concept of reducing renal glucose reabsorption for the treatment of diabetes. I review the structure and advancing profile of various SGLT2 inhibitors, comparing their similarities and differences, and discuss the expected SGLT2 inhibitors for an emerging category of antidiabetic drugs.

Managing type 2 diabetes in the primary care setting: beyond glucocentricity

Successful management of type 2 diabetes mellitus (T2DM) requires attention to additional conditions often associated with hyperglycemia including overweight or obesity, dyslipidemia and hypertension, as each has some relationship with microvascular or macrovascular complications. Because control of cardiovascular risk factors is as important as glucose control in T2DM, these risk factors need to be addressed, and it is critical that antidiabetes medications do not exacerbate these risk factors. A patient-centered approach to treatment in which clinicians maximize patient involvement in the selection of antidiabetes therapy may lead to increased adherence and improved clinical outcomes. The incretin hormones, which include glucagon-like peptide-1 (GLP-1), are involved in glucoregulation and have become an important focus of T2DM research and treatment. Incretin-based therapies, such as the glucagon-like peptide-1 receptor agonists and the dipeptidyl peptidase-IV inhibitors, have shown beneficial effects on hyperglycemia, weight, blood pressure and lipids with a low incidence of hypoglycemia.

Current antihyperglycemic treatment guidelines and algorithms for patients with type 2 diabetes mellitus

Type 2 diabetes mellitus and obesity are associated with increased cardiovascular risk. While lifestyle interventions such as medical nutrition therapy and appropriately prescribed physical activity remain cornerstones of disease prevention and treatment, most patients with type 2 diabetes will eventually require pharmacotherapy for glycemic control. Fortunately, many of these patients are able to achieve desired glycemic targets with the use of currently available antihyperglycemic agents. Both not-for-profit disease-specific organizations and healthcare specialty societies have provided guidance about the appropriate selection of these therapies. Type 2 diabetes treatment guidelines and algorithms have been developed, taking into account a combination of evidence-based information and expert opinions, with various groups offering diverse glucose goals and approaches to hyperglycemia management. Virtually all recognize that type 2 diabetes is a multifaceted disease, necessitating an integrated yet individualized approach to patient care.

Cardiovascular prevention in type 2 diabetes mellitus patients: the role of oral glucose-lowering agents

Diabetes mellitus (DM) is a metabolic disorder that requires medical diagnosis and treatment. Type 2 DM is due to a combination of defective secretion of and responsiveness to insulin. In early stages, the predominant abnormality is reduced insulin sensitivity, and hyperglycemia can be reversed by a variety of measures and medications. In this stage, the cornerstone of glucose-lowering therapy is lifestyle modification, but when counseling does not adequately achieve the recommended glycemic targets, at least five classes of oral drugs are available. In general, alpha-glucosidase inhibitors delay carbohydrate absorption, metiglinides and sulfonylureas increase insulin supply, and biguanides and thiazolidinediones enhance insulin action. Given the high cardiovascular morbidity and mortality in type 2 DM patients, the attempt to reduce cardiovascular complications, beyond the glucose lowering itself, is an extremely relevant task. Indeed, the role of oral glucose-lowering agents concerning hyperglycemia reduction is defined; however, they have not clearly demonstrated to reduce micro- and macrovascular disease, and hitherto, no firm evidence favors one pharmacological treatment over another. The aim of this update is to describe the existing experiences with oral glucose-lowering agents for type 2 DM treatment with respect to cardiovascular prevention.

Incretin mimetics and dipeptidyl peptidase-4 inhibitors: innovative treatment therapies for type 2 diabetes

The prevalence of diabetes and impaired glucose tolerance is predicted to dramatically increase over the next two decades. Clinical therapies for type 2 diabetes mellitus (T2DM) have traditionally included lifestyle modification, oral anti-diabetic agents, and ultimately insulin initiation. In this report, we review the clinical trial results of two innovative T2DM treatment therapies that are based on the glucoregulatory effects of incretin hormones. Incretin mimetics are peptide drugs that mimic several of the actions of glucagon-like peptide-1 (GLP-1) and have been shown to lower glycated hemoglobin (A1C) levels in patients with T2DM. Additionally, incretin mimetics lower postprandial and fasting glucose, suppress elevated glucagon release, and are associated with progressive weight reduction. Dipeptidyl peptidase-4 (DPP-4) inhibitors increase endogenous GLP-1 levels by inhibiting the enzymatic degradation of GLP-1. Clinical studies in patients with T2DM have shown that DPP-4 inhibitors reduce elevated A1C, lower postprandial and fasting glucose, suppress glucagon release, and are weight neutral. Collectively, these new drugs, given in combination with other antidiabetic agents, such as metformin, sulfonylureas, and/or thiazolidinediones, can help restore glucose homeostasis in poorly controlled patients with T2DM.

Reduced attenuation of bone resorption after oral glucose in type 2 diabetes

OBJECTIVE

To investigate the effect of oral glucose on bone resorption and osteoprotegerin (OPG) in subjects with varying degrees of glucose tolerance.

DESIGN AND PATIENTS

In a cross-sectional study, 163 postmenopausal women aged 50-88 years without previous history of diabetes, impaired fasting glucose (IFG) or impaired glucose tolerance (IGT) were recruited. All subjects underwent a 75-g oral glucose tolerance test (OGTT) and were then classified as having normal glucose tolerance (NGT), IFG, IGT or diabetes according to American Diabetes Association (ADA) criteria.

MEASUREMENTS

Plasma glucose, serum insulin, C-terminal telopeptide of type I collagen (CTX-I) and OPG were measured.

RESULTS

Fasting insulin levels increased progressively from subjects with NGT, IFG/IGT to diabetes. After adjusted for age and body mass index (BMI), there was no significant difference in fasting CTX-I and OPG levels across the various degrees of glucose tolerance. After oral glucose, there was a significant decrease in serum CTX-I and OPG (P < 0.001) except for serum OPG in diabetic subjects. In addition, the percentages of change from baseline for both serum CTX-I and OPG were significantly less in diabetic subjects when compared to those in NGT subjects (-40.9% and 0.6% for diabetes and -50.2% and -10.6% for NGT, respectively).

CONCLUSIONS

Oral glucose intake causes suppression of serum CTX-I and OPG in postmenopausal women. The effect is attenuated in women with type 2 diabetes.

Is pancreatic diabetes (type 3c diabetes) underdiagnosed and misdiagnosed?

Exocrine pancreatic insufficiency is frequently associated with diabetes, with high prevalence in both insulin-dependent or insulin-independent patients. Exocrine pancreatic failure has often been perceived as a complication of diabetes. In contrast, recent clinical observations lead to the notion that nonendocrine pancreatic disease is a critical factor for development rather than a sequel to diabetes. The incidence of diabetes caused by exocrine pancreatic disease appears to be underestimated and may comprise 8% or more of the general diabetic patient population. Nonendocrine pancreas disease can cause diabetes by multiple mechanisms. Genetic defects have been characterized, resulting in a syndrome of both exocrine and endocrine failure. Regulation of beta-cell mass and physiological incretin secretion are directly dependent on normal exocrine function. Algorithms for diagnosis and therapy of diabetes should therefore address both endocrine and exocrine pancreatic function.

Dipeptidyl peptidase 4 inhibition with sitagliptin: a new therapy for type 2 diabetes

Sitagliptin is a once-daily, orally active, competitive and fully reversible inhibitor of dipeptidyl peptidase 4, the enzyme that is responsible for the rapid degradation of the incretin hormone glucagon-like peptide-1. It is the first in this new class of antihyperglycaemic agents to gain regulatory approval for the treatment of Type 2 diabetes, both as a monotherapy and for use in combination with metformin or a thiazolidinedione. In clinical trials of < or = 1-year duration, sitagliptin improves glycaemic control by reducing both fasting and postprandial glucose concentrations, leading to clinically meaningful reductions in glycosylated haemoglobin levels. It is safe and well tolerated, with a side-effect profile that is similar to that of the placebo, a low incidence of hypoglycaemia and body weight neutrality. Further clinical experience with sitagliptin will reveal its long-term durability, safety and efficacy.