Novel pharmacologic agents for type 2 diabetes

Transcriptional signature of islet neogenesis-associated protein peptide-treated rat pancreatic islets reveals induction of novel long non-coding RNAs

Background

Diabetes mellitus is characterized by chronic hyperglycemia with loss of β-cell function and mass. An attractive therapeutic approach to treat patients with diabetes in a non-invasive way is to harness the innate regenerative potential of the pancreas. The Islet Neogenesis-Associated Protein pentadecapeptide (INGAP-PP) has been shown to induce β-cell regeneration and improve their function in rodents. To investigate its possible mechanism of action, we report here the global transcriptional effects induced by the short-term INGAP-PP in vitro treatment of adult rat pancreatic islets.

Methods and findings

Rat pancreatic islets were cultured in vitro in the presence of INGAP-PP for 4 days, and RNA-seq was generated from triplicate treated and control islet samples. We performed a de novo rat gene annotation based on the alignment of RNA-seq reads. The list of INGAP-PP-regulated genes was integrated with epigenomic data. Using the new gene annotation generated in this work, we quantified RNA-seq data profiled in INS-1 cells treated with IL1β, IL1β+Calcipotriol (a vitamin D agonist) or vehicle, and single-cell RNA-seq data profiled in rat pancreatic islets. We found 1,669 differentially expressed genes by INGAP-PP treatment, including dozens of previously unannotated rat transcripts. Genes differentially expressed by the INGAP-PP treatment included a subset of upregulated transcripts that are associated with vitamin D receptor activation. Supported by epigenomic and single-cell RNA-seq data, we identified 9 previously unannotated long noncoding RNAs (lncRNAs) upregulated by INGAP-PP, some of which are also differentially regulated by IL1β and vitamin D in β-cells. These include Ri-lnc1, which is enriched in mature β-cells.

Conclusions

Our results reveal the transcriptional program that could explain the enhancement of INGAP-PP-mediated physiological effects on β-cell mass and function. We identified novel lncRNAs that are induced by INGAP-PP in rat islets, some of which are selectively expressed in pancreatic β-cells and downregulated by IL1β treatment of INS-1 cells. Our results suggest a relevant function for Ri-lnc1 in β-cells. These findings are expected to provide the basis for a deeper understanding of islet translational results from rodents to humans, with the ultimate goal of designing new therapies for people with diabetes.

Pharmacotherapy of type 2 diabetes: An update and future directions

Type 2 diabetes (T2D) is a widely prevalent disease with substantial economic and social impact for which multiple conventional and novel pharmacotherapies are currently available; however, the landscape of T2D treatment is constantly changing as new therapies emerge and the understanding of currently available agents deepens. This review aims to provide an updated summary of the pharmacotherapeutic approach to T2D. Each class of agents is presented by mechanism of action, details of administration, side effect profile, cost, and use in certain populations including heart failure, non-alcoholic fatty liver disease, obesity, chronic kidney disease, and older individuals. We also review targets of novel therapeutic T2D agent development. Finally, we outline an up-to-date treatment approach that starts with identification of an individualized goal for glycemic control then selection, initiation, and further intensification of a personalized therapeutic plan for T2D.

Medicinal Plants Qua Glucagon-Like Peptide-1 Secretagogue via Intestinal Nutrient Sensors

Glucagon-like peptide-1 (GLP-1) participates in glucose homeostasis and feeding behavior. Because GLP-1 is rapidly inactivated by the enzymatic cleavage of dipeptidyl peptidase-4 (DPP4) long-acting GLP-1 analogues, for example, exenatide and DPP4 inhibitors, for example, liraglutide, have been developed as therapeutics for type 2 diabetes mellitus (T2DM). However, the inefficient clinical performance and the incidence of side effects reported on the existing therapeutics for T2DM have led to the development of a novel therapeutic strategy to stimulate endogenous GLP-1 secretion from enteroendocrine L cells. Since the GLP-1 secretion of enteroendocrine L cells depends on the luminal nutrient constituents, the intestinal nutrient sensors involved in GLP-1 secretion have been investigated. In particular, nutrient sensors for tastants, cannabinoids, and bile acids are able to recognize the nonnutritional chemical compounds, which are abundant in medicinal plants. These GLP-1 secretagogues derived from medicinal plants are easy to find in our surroundings, and their effectiveness has been demonstrated through traditional remedies. The finding of GLP-1 secretagogues is directly linked to understanding of the role of intestinal nutrient sensors and their recognizable nutrients. Concurrently, this study demonstrates the possibility of developing novel therapeutics for metabolic disorders such as T2DM and obesity using nutrients that are readily accessible in our surroundings.

Recent and emerging therapeutic medications in type 2 diabetes mellitus: incretin-based, Pramlintide, Colesevelam, SGLT2 Inhibitors, Tagatose, Succinobucol

Nearly 285 million people worldwide, with 10% being Americans, suffer from diabetes mellitus and its associated comorbidities. This is projected to increase by 6.5% per year, with 439 million inflicted by year 2030. Both morbidity and mortality from diabetes stem from the consequences of microvascular and macrovascular complications. Of the 285 million with diabetes, over a quarter of a million die per year from related complications, making diabetes the fifth leading cause of death in high-income countries. These startling statistics illustrate the therapeutic failure of current diabetes drugs to retard the progression of diabetes. These statistics further illustrate the continual need for further research and development of alternative drugs with novel mechanisms to slow disease progression and disease complications. The treatment algorithm updated in 2008 by American Diabetes Association and the European Association for the Study of Diabetes currently recommends the traditional medications of metformin, either as monotherapy or in combination with sulfonylurea or insulin, as the preferred choice in the tier 1 option. The algorithm only suggests addition of alternative medications such as pioglitazone and incretin-based drugs as second-line agents in the tier 2 "less well-validated" option. However, these traditional medications have not proven to delay the progressive course of diabetes as evidence of increasing need over time for multiple drug therapy to maintain sufficient glycemic control. Because current diabetes medications have limited efficacy and untoward side effects, the development of diabetes mellitus drugs with newer mechanisms of action continues. This article will review the clinical data on the newly available incretin-based drugs on the market, including glucagon-like peptide agonists and of dipeptidyl peptidase type-4 inhibitors. It will also discuss 2 unique medications: pramlintide, which is indicated for both type and type-2 diabetes, and colesevelam, which is approved by the United States Food and Drug Administration for both type-2 diabetes and hyperlipidemia. It will further review the clinical data on the novel emerging agents of sodium-glucose cotransporter-2 inhibitors, tagatose, and succinobucol, all currently in phase III clinical trials. This review article can serve as an aid for clinicians to identify clinical indications in which these new agents can be applied in the treatment algorithm.

Clinical experience with Liraglutide in 196 patients with type 2 diabetes from a tertiary care center in India

CONTEXT

GLP-1 receptor agonists (GLP-1 RA) are unique antidiabetic agents that have the ability to lower blood glucose without causing hypoglycemia, while at the same time promoting weight loss. Information on the efficacy and safety of GLP-1 RA in the Indian diabetic population is limited.

AIMS

(1) To evaluate the effect of GLP-1 RA, Liraglutide on glycemic control, and weight in obese Indian patients with type 2 diabetes. (2) To study the adverse event profile of Liraglutide in these patients in real-world clinical setting.

SETTINGS AND DESIGN

Observational study conducted in a tertiary care hospital.

MATERIALS AND METHODS

Liraglutide was prescribed to 196 obese patients with type 2 diabetes who had poor glycemic control on oral medications ± insulin. The initial dose of Liraglutide was 0.6 mg, which was up-titrated to 1.2 mg after 1 week; further up-titration to 1.8 mg was done based on tolerance. Dipeptidyl peptidase-IV (DPP-IV) inhibitors were discontinued and dose of other medications adjusted according to clinical judgment during the study period.

RESULTS

Mean age of patients was 49.9 ± 9.6 years. Three month data were available for 175 patients out of a total of 196. At 3 months, glycosylated hemoglobin (HbA1c) was 7.6 ± 0.9% vs. 9.2 ± 1.9% at baseline (P = 0.007) and mean body weight was 96.0 ± 16.5 kg vs. 100.1 ± 17.5 kg at baseline (P < 0.001). Most common adverse events were nausea, burping, and eructation (10%).

CONCLUSION

Liraglutide significantly improves glycemic control with low risk of hypoglycemia and is associated with significant weight loss in obese Indian patients with type 2 diabetes mellitus.

Mechanisms of action of islet neogenesis-associated protein: comparison of the full-length recombinant protein and a bioactive peptide

Islet neogenesis-associated protein (INGAP) was discovered in the partially duct-obstructed hamster pancreas as a factor inducing formation of new duct-associated islets. A bioactive portion of INGAP, INGAP(104-118) peptide (INGAP-P), has been shown to have neogenic and insulin-potentiating activity in numerous studies, including recent phase 2 clinical trials that demonstrated improved glucose homeostasis in both type 1 and type 2 diabetic patients. Aiming to improve INGAP-P efficacy and to understand its mechanism of action, we cloned the full-length protein (rINGAP) and compared the signaling events induced by the protein and the peptide in RIN-m5F cells that respond to INGAP with an increase in proliferation. Here, we show that, although both rINGAP and INGAP-P signal via the Ras/Raf/ERK pathway, rINGAP is at least 100 times more efficient on a molar basis than INGAP-P. For either ligand, ERK1/2 activation appears to be pertussis toxin sensitive, suggesting involvement of a G protein-coupled receptor(s). However, there are clear differences between the peptide and the protein in interactions with the cell surface and in the downstream signaling. We demonstrate that fluorescent-labeled rINGAP is characterized by clustering on the membrane and by slow internalization (≤5 h), whereas INGAP-P does not cluster and is internalized within minutes. Signaling by rINGAP appears to involve Src, in contrast to INGAP-P, which appears to activate Akt in addition to the Ras/Raf/ERK1/2 pathway. Thus our data suggest that interactions of INGAP with the cell surface are important to consider for further development of INGAP as a pharmacotherapy for diabetes.

Pramlintide, the synthetic analogue of amylin: physiology, pathophysiology, and effects on glycemic control, body weight, and selected biomarkers of vascular risk

Pramlintide is a synthetic version of the naturally occurring pancreatic peptide called amylin. Amylin and pramlintide have similar effects on lowering postprandial glucose, lowering postprandial glucagon and delaying gastric emptying. Pramlintide use in type 1 and insulin requiring type 2 diabetes mellitus (DM) is associated with modest reductions in HbA1c often accompanied by weight loss. Limited data show a neutral effect on blood pressure. Small studies suggest small reductions in LDL-cholesterol in type 2 DM and modest reductions in triglycerides in type 1 DM. Markers of oxidation are also reduced in conjunction with reductions in postprandial glucose. Nausea is the most common side effect. These data indicate that pramlintide has a role in glycemic control of both type 1 and type 2 DM. Pramlintide use is associated with favorable effects on weight, lipids and other biomarkers for atherosclerotic disease.

Epidermal growth factor increases insulin secretion and lowers blood glucose in diabetic mice

Epidermal growth factor (EGF) is synthesized in the pancreas and diabetic animals have low levels of EGF. However, the role of EGF in regulating the major function of the pancreas, insulin secretion, has not been studied. Here, we show that EGF rapidly increased insulin secretion in mouse pancreatic islets, as well as in a pancreatic β-cell line. These events were dependent on a Ca²⁺ influx and phospholipase D (PLD) activity, particularly PLD2, as determined using pharmacological blockers and molecular manipulations such as over-expression and siRNA of PLD isozymes. In addition, EGF also increased plasma insulin levels and mediated glucose lowering in normal and diabetic mice. Here, for the first time, we provide evidence that EGF is a novel secretagogue that regulates plasma glucose levels and a candidate for the development of therapeutics for diabetes.

New Therapeutic Options for the Management of Diabetes

Objective: To review new hypoglycemic and antihyperglycemic agents recently approved for the treatment of type 1 and type 2 diabetes mellitus.Data Sources: A MEDLINE search of articles published from 1966 to March 2006 was conducted to identify English-language literature available on the newer therapies approved for the treatment of diabetes. Search terms used were: Byetta, exenatide, insulin detemir, NN304, Exubera inhaled insulin, Levemir, pramlintide, Symlin, AC137, AC0137, and Tripro-Amylin. These articles, abstracts, and data provided by the pharmaceutical manufacturers were reviewed to identify pertinent data. Additional references were obtained from the bibliographies of these publications.Study Selection: Randomized, English-language studies investigating safety or efficacy data on these newer agents with a focus on human studies.Data Extraction: These hypoglycemic and antihyperglycemic agents were reviewed with regard to background information, pharmacokinetic and pharmacodynamic data, relevant clinical studies, U.S. Food and Drug Administration-approved indications, dosing and administration, contraindications, drug interactions, adverse effects, storage, cost, availability, and role in therapy.Data Synthesis: Over the last decade, management options for the treatment of diabetes have exploded. Among these are the incretin mimetics, amylin analogs, insulin analogs, and inhaled insulin. Short-term studies demonstrate that each of these therapies may offer specific advantages such as improved glycemia, convenience, and/or weight loss. Continued study of the incretin mimetics, amylin analogs, and inhaled insulin will be needed to verify long-term safety and efficacy of these agents.Conclusions: These agents with novel mechanisms of action and a new insulin-delivery device offer patients and clinicians additional options that improve glycemic and nonglycemic factors while addressing some of the concerns of older agents. Longerterm studies will help providers weigh the benefits, adverse effects, cost, and unknown long-term risks of these medications.

Diabetes: the latest trends in glycemic control

The increasing pervasiveness of diabetes mellitus on a global stage has been well documented. Many groundbreaking studies have detailed the consequences of inadequate glycemic control, but only recently have data supported evidence that demonstrates benefits in the acute setting. Consensus is lacking with regard to how to achieve glycemic control in the hospital setting. This article discusses glycemic control, with special emphasis on the perioperative patient. Emerging therapeutic treatments and less frequently encountered protocols such as insulin pump management and insulin infusion are considered.

Differential effects of oral hypoglycemic agents on glucose control and cardiovascular risk

Cardiovascular disease (CVD) burden remains the predominant cause of mortality and morbidity in the United States and in most of the developed world. The ongoing twin epidemics of obesity and type 2 diabetes mellitus provide a groundswell source for sustaining this trend for the foreseeable future (increasing the prevalence of CVD by 2-4 times), unless radical changes are made in public health policy. Oral hypoglycemic agents (OHAs) remain a mainstay for management of type 2 diabetes in most practice settings. Although these agents are primarily prescribed to achieve better glycemic control, it is important to evaluate what effects they have on cardiovascular risk and whether there are significant differences in effects among the different OHAs. This review presents the available data on the effects of the various OHAs on cardiovascular risk surrogates and actual events in retrospective and prospective study design settings.

Exenatide: A Novel Approach for Treatment of Type 2 Diabetes

Exenatide (synthetic exendin-4) is the analog of glucagon-like peptide 1 (GLP-1), the major physiologic incretin. The latter is an intestinal hormone that enhances glucose-induced insulin secretion after meals. In addition, GLP-1 stimulates insulin synthesis, inhibits glucagon secretion, delays gastric emptying, and may promote satiety. These glucoregulatory actions help control plasma glucose in the postprandial period. However, in diabetes, the GLP-1 response to nutrient intake is impaired, leading to exacerbation of postprandial hyperglycemia. Exenatide was recently approved as adjunctive therapy in diabetic patients failing sulfonylureas and/or metformin. In clinical trials lasting 30 weeks, exenatide therapy was associated with moderate reduction in mean hemoglobin A1c (HbA1c) levels of approximately 0.8%, and an average weight loss of approximately 2 kg compared with baseline. Hypoglycemia was generally mild and occurred more commonly when exenatide was used in conjunction with sulfonylureas. The requirement of subcutaneous injections twice a day, and the frequent occurrence of nausea and vomiting, represent the main limitations of exenatide. Nevertheless, this agent may be a useful add-on therapy in obese diabetic patients with suboptimal control as a result of continuing weight gain and/or severe postprandial hyperglycemia. The introduction of GLP-1-based antidiabetic drugs is a novel and promising strategy to treat diabetes.

Is Exenatide A Useful Addition to Diabetes Therapy?

OBJECTIVE

To present an evidence-based evaluation of the antidiabetic drug exenatide.

METHODS

The English literature from 1965 to January 2006 was reviewed by using data sources from MED-LINE, endocrinology textbooks, and manual searching of cross-references from original articles and reviews.

RESULTS

Glucagon-like peptide-1 (GLP-1) is the major physiologic incretin, a gut-derived hormone that enhances glucose-induced insulin secretion. Moreover, GLP-1 inhibits glucagon secretion, delays gastric emptying, and may promote satiety, leading to reduction of postprandial glucose levels. Exenatide (AC-2993, synthetic exendin-4) is a GLP-1 analogue that was recently approved as adjunctive therapy in patients with diabetes in whom sulfonylureas, metformin, or both have failed. Exenatide is administered by subcutaneous injections twice daily. The use of exenatide has been associated with a mean reduction in hemoglobin A1c levels of approximately 0.8% and a mean weight loss of approximately 2 kg after 30 weeks of therapy in comparison with baseline. Treatment-related hypoglycemia was generally mild and occurred more commonly in association with the use of sulfonylureas. In 5% to 10% of patients, however, exenatide could not be tolerated, mainly because of nausea and vomiting.

CONCLUSION

Exenatide is a moderately effective antidiabetic agent. Mild degrees of weight loss and hypoglycemia are its main advantages, whereas the frequent occurrence of nausea and vomiting and the requirement of subcutaneous administration are its strongest limitations. Nevertheless, this new drug may be a useful add-on therapy in obese patients with diabetes who have suboptimal control of their disease as a result of continuing weight gain, severe postprandial hyperglycemia, or both.

New-onset diabetes and antihypertensive drugs

Observational studies have provided evidence that a consistent fraction (approximately 15-20%) of hypertensive patients displays a glucose intolerance state that may be aggravated by antihypertensive drug regimens based on thiazide diuretics or beta-blockers. This review examines the relative and absolute diabetogenic effects of antihypertensive drugs, by comparing the impact of 'new' (calcium antagonists, angiotensin-converting enzyme inhibitors and angiotensin II receptor antagonists) versus 'old' (diuretics and beta-blockers) drugs on new-onset diabetes in recent clinical trials. Evidence is provided that compared with diuretics and beta-blockers, new-onset diabetes is less common with 'new' drugs, and that conventional antihypertensive compounds, particularly when combined together, may amplify the natural time-dependent tendency towards the development of this metabolic disease. This paper provides new insights into the potential mechanisms responsible for the phenomenon and the clinical significance of antihypertensive drug-induced diabetes.

Dual-action peptides: a new strategy in the treatment of diabetes-associated neuropathy

Peripheral neuropathy is one of the most common and debilitating complications of type 1 and type 2 diabetes mellitus. Recent studies have shown that several small, non-neural peptides possess neurotrophic activity and exert beneficial effects on nervous system function in experimental and clinical diabetes. Two of these, C-peptide and islet neogenesis-associated protein peptide, are derived from pancreatic proteins and use related signal transduction mechanisms. Derivatives of erythropoietin possess similar properties in the nervous system. As a group, these peptides are of increasing interest as leads to potential new approaches in the treatment of diabetes-associated neuropathies and other neurodegenerative conditions. This review addresses the recent advances made with these peptides in the context of diabetic neuropathy, and highlights similarities and differences in their mechanisms of action from the perspective of combination therapy.

Oral agents in managing diabetes mellitus in children and adolescents

Type 2 diabetes mellitus is a chronic disease with potentially devastating long-term complications. Despite the tremendous body of research and experience in the adult population, relatively little is established regarding this condition and its optimal management in children and adolescents. The pediatric community awaits results of ongoing trials as well as further study of optimal intervention in children, as they continue to extrapolate management practices from their adult counterparts.