Biochemical and histological effects of exendin-4 (exenatide) on the rat pancreas

Diabetes, antihyperglycemic medications and cancer risk: smoke or fire?

OBJECTIVE

The aim of this review article is to discuss the epidemiological links between diabetes and cancer; the potential biological mechanisms linking diabetes, obesity and cancer; the risk of cancer associated with antidiabetic medications.

METHODS

The data discussed in this review were obtained from the American Association of Clinical Endocrinologists Consensus Conference on Diabetes and Cancer, held in New York, NY, USA, September 2012.

RESULTS

The results of these studies demonstrate a significant association between diabetes and the risk of multiple cancers, including hepatocellular, pancreatic, endometrial, colorectal, breast, kidney, bladder, gastric, and ovarian cancer, non-Hodgkin lymphoma, T cell lymphoma and leukemia. There are multiple potential biological mechanisms that may link type 2 diabetes, obesity and cancer. Insulin resistance and hyperinsulinemia may lead to direct activation of the insulin receptors on tumor cells and promote tumor growth. Other potential mechanisms include increased circulating, local or bioavailable insulin-like growth factor 1, hyperglycemia, dyslipidemia, increased circulating or local estrogen, adipokines and direct and indirect effects of inflammatory cytokines. Epidemiological studies have had conflicting results regarding the associations between various classes of antidiabetic medication and cancer development. Animal studies have demonstrated increased tumor growth with certain medications, but their relevance to humans is uncertain. Metformin may, however, have protective effects on cancer development and may improve survival in patients with cancer.

CONCLUSION

We describe the current understanding of the links among diabetes, antidiabetic medication and cancer risk. We highlight some of the issues that should be addressed in the future to prevent cancer development and death in those with diabetes.

Glucagon-like peptide-1 receptor agonist treatment reduces beta cell mass in normoglycaemic mice

AIMS/HYPOTHESIS

Incretin-based therapies improve glycaemic control in patients with type 2 diabetes. In animal models of diabetes, glucagon-like peptide-1 receptor agonists (GLP-1RAs) increase beta cell mass. GLP-1RAs are also evaluated in non-diabetic individuals with obesity and cardiovascular disease. However, their effect on beta cell mass in normoglycaemic conditions is not clear. Here, we investigate the effects of the GLP-1RA liraglutide on beta cell mass and function in normoglycaemic mice.

METHODS

C57BL/6J mice were treated with the GLP-1RA liraglutide or PBS and fed a control or high-fat diet (HFD) for 1 or 6 weeks. Glucose and insulin tolerance tests were performed after 6 weeks. BrdU was given to label proliferating cells 1 week before the animals were killed. The pancreas was taken for either histology or islet isolation followed by a glucose-induced insulin-secretion test.

RESULTS

Treatment with liraglutide for 6 weeks led to increased insulin sensitivity and attenuation of HFD-induced insulin resistance. A reduction in beta cell mass was observed in liraglutide-treated control and HFD-fed mice at 6 weeks, and was associated with a lower beta cell proliferation rate after 1 week of treatment. A similar reduction in alpha cell mass occurred, resulting in an unchanged alpha to beta cell ratio. In contrast, acinar cell proliferation was increased. Finally, islets isolated from liraglutide-treated control mice had enhanced glucose-induced insulin secretion.

CONCLUSIONS/INTERPRETATION

Our data show that GLP-1RA treatment in normoglycaemic mice leads to increases in insulin sensitivity and beta cell function that are associated with reduced beta cell mass to maintain normoglycaemia.

A critical analysis of the clinical use of incretin-based therapies: Are the GLP-1 therapies safe?

There is no question that incretin-based glucose-lowering medications have proven to be effective glucose-lowering agents. Glucagon-like peptide 1 (GLP-1) receptor agonists demonstrate an efficacy comparable to insulin treatment and appear to do so with significant effects to promote weight loss with minimal hypoglycemia. In addition, there are significant data with dipeptidyl peptidase 4 (DPP-4) inhibitors showing efficacy comparable to sulfonylureas but with weight neutral effects and reduced risk for hypoglycemia. However, over the recent past there have been concerns reported regarding the long-term consequences of using such therapies, and the issues raised are in regard to the potential of both classes to promote acute pancreatitis, to initiate histological changes suggesting chronic pancreatitis including associated preneoplastic lesions, and potentially, in the long run, pancreatic cancer. Other issues relate to a potential risk for the increase in thyroid cancer. There are clearly conflicting data that have been presented in preclinical studies and in epidemiologic studies. To provide an understanding of both sides of the argument, we provide a discussion of this topic as part of this two-part point-counterpoint narrative. In the point narrative below, Dr. Butler and colleagues provide their opinion and review of the data to date and that we need to reconsider the use of incretin-based therapies because of the growing concern of potential risk and based on a clearer understanding of the mechanism of action. In the counterpoint narrative following the contribution by Dr. Butler and colleagues, Dr. Nauck provides a defense of incretin-based therapies and that the benefits clearly outweigh any concern of risk.

The effects of dipeptidyl-peptidase-IV inhibitor, vildagliptin, on the exocrine pancreas in spontaneously diabetic Goto-Kakizaki rats

OBJECTIVES

The risk of adverse effects of dipeptidyl peptidase-4 inhibitors on the exocrine pancreas, particularly the high risk of pancreatitis, is controversial. In this study, we examined the exocrine pancreatic function and structure in spontaneously diabetic Goto-Kakizaki (GK) rats treated with a dipeptidyl peptidase-4 inhibitor.

METHODS

Male GK rats and normal Wistar rats 4 weeks of age were treated with vildagliptin (VG; 30 mg/kg/d) for 18 weeks. Subsequently, exocrine pancreatic pathology and function in treated animals were compared to those in untreated animals.

RESULTS

In GK rats, VG treatment suppressed elevated serum concentrations of amylase and lipase, reduced lymphocytic infiltration around ducts, around vessels, and in acinar areas, and reduced the frequency of apoptotic acinar cells and ductule formation (both of which occurred more frequently in GK rats than Wistar rats). However, VG treatment had no effect on the proliferation rate of pancreatic duct glandular cells (which was low in GK rats) and of cells in the main ducts, peripheral ducts, and acini (which was similar in all groups).

CONCLUSIONS

Perturbations of exocrine pancreatic function and structure in GK rats are ameliorated by long-term VG treatment.

A critical analysis of the clinical use of incretin-based therapies: The benefits by far outweigh the potential risks

There is no question that incretin-based glucose-lowering medications have proven to be effective glucose-lowering agents. Glucagon-like peptide 1 (GLP-1) receptor agonists demonstrate an efficacy comparable to insulin treatment and appear to do so with significant effects to promote weight loss with minimal hypoglycemia. In addition, there are significant data with dipeptidyl peptidase 4 (DPP-4) inhibitors showing efficacy comparable to sulfonylureas but with weight neutral effects and reduced risk for hypoglycemia. However, over the recent past there have been concerns regarding the long-term consequences of using such therapies, and the issues raised are in regard to the potential of both classes to promote acute pancreatitis, to initiate histological changes suggesting chronic pancreatitis including associated preneoplastic lesions, and potentially, in the long run, pancreatic cancer. Other issues relate to an increase in thyroid cancer. There are clearly conflicting data that have been presented in preclinical studies and in epidemiologic studies. To provide an understanding of both sides of the argument, we provide a discussion of this topic as part of this two-part point-counterpoint narrative. In the point narrative preceding the counterpoint narrative below, Dr. Butler and colleagues provide their opinion and review of the data to date and that we need to reconsider use of incretin-based therapies because of the growing concern of potential risk and based on a clearer understanding of the mechanism of action. In the counterpoint narrative provided below, Dr. Nauck provides a defense of incretin-based therapies and that benefits clearly outweigh any concern of risk.

Pharmacology, physiology, and mechanisms of incretin hormone action

Incretin peptides, principally GLP-1 and GIP, regulate islet hormone secretion, glucose concentrations, lipid metabolism, gut motility, appetite and body weight, and immune function, providing a scientific basis for utilizing incretin-based therapies in the treatment of type 2 diabetes. Activation of GLP-1 and GIP receptors also leads to nonglycemic effects in multiple tissues, through direct actions on tissues expressing incretin receptors and indirect mechanisms mediated through neuronal and endocrine pathways. Here we contrast the pharmacology and physiology of incretin hormones and review recent advances in mechanisms coupling incretin receptor signaling to pleiotropic metabolic actions in preclinical studies. We discuss whether mechanisms identified in preclinical studies have potential translational relevance for the treatment of human disease and highlight controversies and uncertainties in incretin biology that require resolution in future studies.

No evidence of drug-induced pancreatitis in rats treated with exenatide for 13 weeks

AIMS

The potential association of glucagon-like peptide receptor agonists (GLP-1RAs) with the development of pancreatitis or pancreatic malignancies in patients with diabetes has been suggested. This study evaluated the long-term effects of the GLP-1RA exenatide on pancreatic exocrine structure and function in the Zucker diabetic fatty (ZDF) rat model of type 2 diabetes.

METHODS

Rats received subcutaneous twice-daily injections of 0 (control), 6, 40 and 250 µg/kg/day exenatide for 3 months. Clinical signs, body and pancreas weight, food consumption, HbA1c, fasting serum amylase, lipase, glucose and insulin concentrations were evaluated during treatment and after a 28-day off-drug period to assess the reversibility of any observed effects. Morphometric analysis of pancreatic ductal cell proliferation and apoptosis were performed.

RESULTS

Plasma exenatide concentrations were several-fold higher than therapeutic levels observed in humans. No exenatide-related effects were observed on clinical signs, lipase concentration, pancreatic weight, pancreatic histology, ductal cell proliferation or apoptosis. Exenatide improved animal survival, physical condition, glucose concentrations and HbA1c, decreased food intake, and increased serum insulin concentration. Total amylase concentrations, although within normal ranges, were slightly higher in exenatide-treated rats; following the off-drug period, total amylase concentrations were comparable in treated and untreated rats. Exenatide-related minimal-to-moderate islet hypertrophy was observed at doses ≥6 µg/kg/day, with dose-related increases in incidence and degree. These changes were still present after the off-drug period.

CONCLUSIONS

Chronic administration of exenatide in ZDF rats resulted in the expected metabolic benefits and improved animal survival, with no adverse effects noted on pancreatic exocrine structure and function.

Incretin-based therapies in the treatment of type 2 diabetes--more than meets the eye?

A lot of contradictory data regarding the serious side effects of incretin-based therapies are currently available, with more being prepared or published every month. Considering the widespread use of these drugs it should be considered a priority to establish both short- and long-term risks connected with incretin treatment. We performed an extensive literature search of the PubMed database looking for articles dealing with connections between incretin-based therapies and pancreatitis, pancreatic cancer, thyroid cancer and other neoplasms. Data obtained indicate that GLP-1 agonists and DPPIV inhibitors could increase the risk of pancreatitis and pancreatic cancer, possibly due to their capacity to increase ductal cell turnover, which has previously been found to be up-regulated in patients with obesity and T2DM. GLP-1 analogues exenatide and liraglutide seem to be connected with medullary thyroid carcinoma in rat models and, surprisingly, GLP-1 receptors have been found in papillary thyroid carcinoma, currently the most common neoplasm of the thyroid gland in humans. Changes in expression of DPPIV have been described in ovarian carcinoma, melanoma, endometrial adenocarcinoma, prostate cancer, non-small cell lung cancer and in certain haematological malignancies. In most cases loss of DPPIV activity is connected with a higher grading scale, more aggressive tumour behaviour and higher metastatic potential. In conclusion animal and human studies indicate that there could be a connection between incretin-based therapies and pancreatitis, pancreatic cancer, thyroid cancer and other neoplasms. Therefore whenever such therapy is started it would be wise to proceed with caution, especially if personal history of neoplasms is present.

Relative risk of acute pancreatitis in initiators of exenatide twice daily compared with other anti-diabetic medication: a follow-up study

AIMS

Previously, a retrospective cohort study found no increased risk of acute pancreatitis with current or recent use of exenatide twice daily compared with use of other anti-diabetic drugs. This follow-up study investigated incident acute pancreatitis, with the use of a different data source and analytic method, in patients exposed to exenatide twice daily compared with patients exposed to other anti-diabetic medications.

METHODS

A large US health insurance claims database was used. Eligible patients had ≥ 9 months continuous enrollment without a claim for pancreatitis and a claim for a new anti-diabetic medication on or after 1 June 2005 to 31 March 2009. Cases of acute pancreatitis were defined as hospitalized patients with an Internation Classification of Disease 9 code of 577.0 in the primary position. A discrete time survival model was used to evaluate the relationship between exenatide twice daily and acute pancreatitis.

RESULTS

Of 482,034 eligible patients, 24,237 initiated exenatide twice daily and 457,797 initiated another anti-diabetic medication. Initiators of exenatide twice daily had more severe diabetes compared with initiators of other anti-diabetic medications. After adjustments for propensity score, insulin and use of medication potentially associated with acute pancreatitis, the odds ratio with exenatide twice daily exposure was 0.95 (95% CI 0.65-1.38). A secondary analysis that examined current, recent and past medication exposure found no increased risk of acute pancreatitis with exenatide twice daily, regardless of exposure category.

CONCLUSION

This study indicates that exposure to exenatide twice daily was not associated with an increased risk of acute pancreatitis compared with exposure to other anti-diabetic medications. These results should be interpreted in light of potential residual confounding and unknown biases.

A case of severe acute necrotizing pancreatitis after administration of sitagliptin

A 55-year-old Japanese man with a 3-year history of type 2 diabetes mellitus was admitted to our hospital for upper abdominal pain. Control of diabetes mellitus was good with voglibose and metformin, with sitagliptin added to this regimen 8 months prior. His pancreatic enzyme levels were elevated, and abdominal computed tomography (CT) showed diffuse pancreatic swelling with fluid accumulation and ascites of CT grade 3. The patient was diagnosed with severe acute pancreatitis. There were no obvious causes for pancreatitis except the recently administered sitagliptin. Since incretin-related drugs entered the market, the number of incretin-related drugs prescriptions rapidly increased and so did the incidence of pancreatitis. There are several reports suggesting the correlation between incretin-related drugs and pancreatitis, such as a report based on data obtained from the United States Food and Drug Administration (FDA) which revealed a significant correlation between the administration of exenatide or sitagliptin and pancreatitis. However, there also is a report that denied the evidence for such in a large cohort study. The relation between incretin based drugs and pancreatitis is still controversial.

Elevated amylase and lipase levels in patients using glucagonlike peptide-1 receptor agonists or dipeptidyl-peptidase-4 inhibitors in the outpatient setting

OBJECTIVE

To 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.

METHODS

In 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 type 2 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.

RESULTS

Among 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.

CONCLUSION

Both GLP-1 receptor agonists and DPP-4 inhibitors are associated with increased levels of serum lipase more than serum amylase in many patients with type 2 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.

Acting on Hormone Receptors with Minimal Side Effect on Cell Proliferation: A Timely Challenge Illustrated with GLP-1R and GPER

G protein-coupled receptors (GPCRs) constitute a large family of receptors that sense molecules outside the cell and activate inside signal transduction pathways and cellular responses. GPCR are involved in a wide variety of physiological processes, including in the neuroendocrine system. GPCR are also involved in many diseases and are the target of 30% of marketed medicinal drugs. Whereas the majority of the GPCR-targeting drugs have proved their therapeutic benefit, some of them were associated with undesired effects. We develop two examples of used drugs whose therapeutic benefits are tarnished by carcinogenesis risks. The chronic administration of glucagon-like peptide-1 (GLP-1) analogs widely used to treat type-2 diabetes was associated with an increased risk of pancreatic or thyroid cancers. The long-term treatment with the estrogen antagonist tamoxifen, developed to target breast cancer overexpressing estrogen receptors ER, presents agonist activity on the G protein-coupled estrogen receptor which is associated with an increased incidence of endometrial cancer and breast cancer resistance to hormonotherapy. We point out and discuss the need of pharmacological studies to understand and overcome the undesired effects associated with the chronic administration of GPCR ligands. In fact, biological effects triggered by GPCR often result from the activation of multiple intracellular signaling pathways. Deciphering which signaling networks are engaged following GPCR activation appears to be primordial to unveil their contribution in the physiological and physiopathological processes. The development of biased agonists to elucidate the role of the different signaling mechanisms mediated by GPCR activation will allow the generation of new therapeutic agents with improved efficacy and reduced side effects. In this regard, the identification of GLP-1R biased ligands promoting insulin secretion without inducing pro-tumoral effects would offer therapeutic benefit.

Discovery and development of exenatide: the first antidiabetic agent to leverage the multiple benefits of the incretin hormone, GLP-1

INTRODUCTION

The GLP-1 receptor agonist exenatide is synthetic exendin-4, a peptide originally isolated from the salivary secretions of the Gila monster. Exenatide was developed as a first-in-class diabetes therapy, with immediate- and extended-release formulations. In preclinical diabetes models, exenatide enhanced glucose-dependent insulin secretion, suppressed inappropriately elevated glucagon secretion, slowed gastric emptying, reduced body weight, enhanced satiety, and preserved pancreatic β-cell function. In clinical trials, both exenatide formulations reduced hyperglycemia in patients with type 2 diabetes mellitus (T2DM) and were associated with weight loss.

AREAS COVERED

This article reviews the development of exenatide from its discovery and preclinical investigations, to the elucidation of its pharmacological mechanisms of action in mammalian systems. The article also presents the pharmacokinetic profiling and toxicology studies of exenatide, as well as its validation in clinical trials.

EXPERT OPINION

GLP-1 receptor agonists represent a new paradigm for the treatment of patients with T2DM. By leveraging incretin physiology, a natural regulatory system that coordinates oral nutrient intake with mechanisms of metabolic control, these agents address multiple core defects in the pathophysiology of T2DM. Studies have identified unique benefits including improvements in glycemic control and weight, and the potential for beneficial effects on the cardiometabolic system without the increased risk of hypoglycemia associated with insulin therapy. Peptide hormone therapeutics can offer significant advantages over small molecule drug targets when it comes to specificity, potency, and more predictable side effects. As exemplified by exenatide, injectable peptides can be important drugs for the treatment of chronic diseases, such as T2DM.

Pancreatitis: a potential complication of liraglutide?

OBJECTIVE

To review the evidence surrounding a potential association between liraglutide and pancreatitis.

DATA SOURCES

A literature search was conducted in MEDLINE (1948-July 12, 2012) and EMBASE (1974-week 27, 2012) using the search terms pancreatitis, liraglutide, and glucagon-like peptide 1/adverse effects. Reference citations from identified publications were reviewed. The manufacturer was contacted and regulatory documents from the Food and Drug Administration website were reviewed for unpublished data related to cases of pancreatitis associated with liraglutide use.

STUDY SELECTION AND DATA EXTRACTION

All identified sources that were published in English were considered for inclusion.

DATA SYNTHESIS

Eleven cases of pancreatitis have been reported in patients taking liraglutide. Seven were from the LEAD (Liraglutide Effect and Action in Diabetes) studies, 1 was reported in the extension of a clinical trial, and 1 was in an unpublished obesity trial. Two were published postmarketing case reports. Nine of the cases reported were diagnosed as acute pancreatitis, while 2 were classified as chronic pancreatitis. The mean age of the patients was 57.5 years and mean body mass index was 33.92 kg/m(2). Six of the 11 cases occurred in male patients. Nine of the patients were white and 1 was African American. In 7 of the cases, onset occurred at liraglutide doses at or above 1.8 mg daily. Common comorbidities included history of pancreatitis, cholelithiasis, and diabetes. One case was fatal.

CONCLUSIONS

Pancreatitis is a potential complication with liraglutide therapy. Liraglutide should be used cautiously in patients at risk of pancreatitis (eg, alcohol abuse, history of pancreatitis, cholelithiasis).

A meta-analysis of serious adverse events reported with exenatide and liraglutide: acute pancreatitis and cancer

AIMS

The association between GLP-1 agonists, acute pancreatitis (AP), any cancer and thyroid cancer is discussed. This meta-analysis was aimed at evaluating the risk of those serious adverse events associated with GLP-1 agonists in patients with type 2 diabetes.

METHODS

Medline, EMBASE, Cochrane Library and clinicaltrials.gov were searched in order to identify longitudinal studies evaluating exenatide or liraglutide use and reporting data on AP or cancer. Odds ratios (ORs) were pooled using a random-effects model. I(2) statistics assessed heterogeneity.

RESULTS

Twenty-five studies were included. Neither exenatide (OR 0.84 [95% CI 0.58-1.22], I(2) = 30%) nor liraglutide (OR 0.97 [95% CI 0.21-4.39], I(2) = 0%) were associated with an increased risk of AP, independent of baseline comparator. The pooled OR for cancer associated with exenatide was 0.86 (95% CI 0.29, 2.60, I(2) = 0%) and for liraglutide was 1.35 (95% CI 0.70, 2.59, I(2) = 0%). Liraglutide was not associated with an increased risk for thyroid cancer (OR 1.54 [95% CI 0.40-6.02], I(2) = 0%). For exenatide, no thyroid malignancies were reported.

CONCLUSIONS

Current available published evidence is insufficient to support an increased risk of AP or cancer associated with GLP-1 agonists. These rare and long-term adverse events deserve properly monitoring in future studies evaluating GLP-1 agonists.

Relative risk of acute pancreatitis in initiators of exenatide twice daily compared with other anti-diabetic medication: a follow-up study

AIMS

Previously, a retrospective cohort study found no increased risk of acute pancreatitis with current or recent use of exenatide twice daily compared with use of other anti-diabetic drugs. This follow-up study investigated incident acute pancreatitis, with the use of a different data source and analytic method, in patients exposed to exenatide twice daily compared with patients exposed to other anti-diabetic medications.

METHODS

A large US health insurance claims database was used. Eligible patients had ≥ 9 months continuous enrollment without a claim for pancreatitis and a claim for a new anti-diabetic medication on or after 1 June 2005 to 31 March 2009. Cases of acute pancreatitis were defined as hospitalized patients with an Internation Classification of Disease 9 code of 577.0 in the primary position. A discrete time survival model was used to evaluate the relationship between exenatide twice daily and acute pancreatitis.

RESULTS

Of 482,034 eligible patients, 24,237 initiated exenatide twice daily and 457,797 initiated another anti-diabetic medication. Initiators of exenatide twice daily had more severe diabetes compared with initiators of other anti-diabetic medications. After adjustments for propensity score, insulin and use of medication potentially associated with acute pancreatitis, the odds ratio with exenatide twice daily exposure was 0.95 (95% CI 0.65-1.38). A secondary analysis that examined current, recent and past medication exposure found no increased risk of acute pancreatitis with exenatide twice daily, regardless of exposure category.

CONCLUSION

This study indicates that exposure to exenatide twice daily was not associated with an increased risk of acute pancreatitis compared with exposure to other anti-diabetic medications. These results should be interpreted in light of potential residual confounding and unknown biases.

GLP1 and cancer: friend or foe?

The new incretin-based therapies, dipeptidyl peptidase-4 (DPP4) inhibitors and glucagon like peptide 1 (GLP1) receptor agonists are widely used for the treatment of type 2 diabetes because of their glucose-lowering capacity with low risk of hypoglycemia. As they are weight neutral or induce weight loss in this mostly overweight population, they are popular among clinicians and patients alike. Nonetheless, concerns have been raised about GLP1's trophic effects. While increased β cell mass observed in rodents sounds appealing for treatment of diabetes, there was also an increased incidence of medullary thyroid cancer (MTC) in some species. We reviewed literature available in the Medline database until March 2012. Safety signals have emerged for MTC and pancreatic carcinoma from adverse event databases in the United States and Europe. Considering the relatively short duration of these studies, it is more likely that premalignant lesions are stimulated in presence of GLP1, rather than new neoplasms induced. Moreover, interpreting results of animal studies is difficult because of species-specific differences in presence and density of GLP1 receptors. Furthermore, data are emerging suggesting beneficial effects of GLP1 on colon and breast cancer. In conclusion, presently, the benefits of using DPP4 inhibitors or GLP1 receptor agonists for treatment of type 2 diabetes outweigh the risks. Nonetheless, their safety profile should be monitored and their indications should be widened cautiously. At present they remain contra-indicated in patients with a personal or family history of MTC or multiple endocrine neoplasia type 2.

The effects of 13 wk of liraglutide treatment on endocrine and exocrine pancreas in male and female ZDF rats: a quantitative and qualitative analysis revealing no evidence of drug-induced pancreatitis

A possible association between glucagon-like peptide-1 (GLP-1) analogs and incidences of pancreatitis has been suggested based on clinical studies. In male and female diabetic Zucker diabetic fatty (ZDF) rats, we investigated the effects of continuous administration of liraglutide and exenatide on biochemical [lipase, pancreatic amylase (P-amylase)] and histopathological markers of pancreatitis. Male and female ZDF rats were dosed for 13 wk with liraglutide (0.4 or 1.0 mg·kg(-1)·day(-1) sc once daily) or exenatide (0.25 mg·kg(-1)·day(-1) sc, Alzet osmotic minipumps). P-amylase and lipase plasma activity were measured, and an extended histopathological and stereological (specific cell mass and proliferation rate) evaluation of the exocrine and the endocrine pancreas was performed. Expectedly, liraglutide and exenatide lowered blood glucose and Hb A(1c) in male and female ZDF rats, whereas β-cell mass and proliferation rate were increased with greatly improved blood glucose control. Whereas neither analog affected lipase activity, small increases in P-amylase activity were observed in animals treated with liraglutide and exenatide. However, concurrent or permanent increases in lipase and P-amylase activity were never observed. Triglycerides were lowered by both GLP-1 analogs. The qualitative histopathological findings did not reveal adverse effects of liraglutide. The findings were mainly minimal in severity and focal in distribution. Similarly, the quantitative stereological analyses revealed no effects of liraglutide or exenatide on overall pancreas weight or exocrine and duct cell mass or proliferation. The present study demonstrates that, in overtly diabetic male and female ZDF rats, prolonged exposure to GLP-1 receptor agonists does not affect biochemical or histopathological markers of pancreatitis, and whereas both exenatide and liraglutide increase β-cell mass, they have no effect on the exocrine pancreas. However, clinical outcome studies and studies using primate tissues and/or studies in nonhuman primates are needed to further assess human risk.

Exenatide and sitagliptin are not associated with increased risk of acute renal failure: a retrospective claims analysis

AIM

This study evaluated whether the risk of acute renal failure (ARF) increases with exenatide and sitagliptin use.

METHODS

A retrospective cohort study of a large medical and pharmacy claims database was performed. Data for 4 91 539 patients were analysed. Cox proportional hazard models were used to compare the risk of ARF between diabetic and non-diabetic subjects and between diabetic patients treated with exenatide, sitagliptin and control medications.

RESULTS

Adjusted Cox analyses showed diabetic subjects had a higher risk of ARF [HR 1.51, confidence interval (CI) 1.26-1.81, p < 0.001] than non-diabetic controls. Compared with diabetic controls, neither exenatide (HR 0.77, CI 0.42-1.41, p = 0.40) nor sitagliptin (HR 1.17, CI 0.82-1.65, p = 0.39) increased the risk of ARF.

CONCLUSION

Our study revealed an increased incidence of ARF in diabetic versus non-diabetic patients but no association between use of exenatide or sitagliptin and ARF. Because of the limitations of this observational analysis, we cannot exclude the possibility of a very small increased risk.

Hypoglycemic and antilipidemic properties of kombucha tea in alloxan-induced diabetic rats

Background

Diabetes has become a serious health problem and a major risk factor associated with troublesome health complications, such as metabolism disorders and liver-kidney dysfunctions. The inadequacies associated with conventional medicines have led to a determined search for alternative natural therapeutic agents. The present study aimed to investigate and compare the hypoglycemic and antilipidemic effects of kombucha and black tea, two natural drinks commonly consumed around the world, in surviving diabetic rats.

Methods

Alloxan diabetic rats were orally supplied with kombucha and black tea at a dose of 5 mL/kg body weight per day for 30 days, fasted overnight, and sacrificed on the 31st day of the experiment. Their bloods were collected and submitted to various biochemical measurements, including blood glucose, cholesterol, triglcerides, urea, creatinine, transaminases, transpeptidase, lipase, and amylase activities. Their pancreases were isolated and processed to measure lipase and α-amylase activities and to perform histological analysis.

Results

The findings revealed that, compared to black tea, kombucha tea was a better inhibitor of α-amylase and lipase activities in the plasma and pancreas and a better suppressor of increased blood glucose levels. Interestingly, kombucha was noted to induce a marked delay in the absorption of LDL-cholesterol and triglycerides and a significant increase in HDL-cholesterol. Histological analyses also showed that it exerted an ameliorative action on the pancreases and efficiently protected the liver-kidney functions of diabetic rats, evidenced by significant decreases in aspartate transaminase, alanine transaminase, and gamma-glytamyl transpeptidase activities in the plasma, as well as in the creatinine and urea contents.

Conclusions

The findings revealed that kombucha tea administration induced attractive curative effects on diabetic rats, particularly in terms of liver-kidney functions. Kombucha tea can, therefore, be considered as a potential strong candidate for future application as a functional supplement for the treatment and prevention of diabetes.

Chronic GLP-1 receptor activation by exendin-4 induces expansion of pancreatic duct glands in rats and accelerates formation of dysplastic lesions and chronic pancreatitis in the Kras(G12D) mouse model

Pancreatic duct glands (PDGs) have been hypothesized to give rise to pancreatic intraepithelial neoplasia (PanIN). Treatment with the glucagon-like peptide (GLP)-1 analog, exendin-4, for 12 weeks induced the expansion of PDGs with mucinous metaplasia and columnar cell atypia resembling low-grade PanIN in rats. In the pancreata of Pdx1-Cre; LSL-Kras(G12D) mice, exendin-4 led to acceleration of the disruption of exocrine architecture and chronic pancreatitis with mucinous metaplasia and increased formation of murine PanIN lesions. PDGs and PanIN lesions in rodent and human pancreata express the GLP-1 receptor. Exendin-4 induced proproliferative signaling pathways in human pancreatic duct cells, cAMP-protein kinase A and mitogen-activated protein kinase phosphorylation of cAMP-responsive element-binding protein, and increased cyclin D1 expression. These GLP-1 effects were more pronounced in the presence of an activating mutation of Kras and were inhibited by metformin. These data reveal that GLP-1 mimetic therapy may induce focal proliferation in the exocrine pancreas and, in the context of exocrine dysplasia, may accelerate formation of neoplastic PanIN lesions and exacerbate chronic pancreatitis.

Rational therapy for diabetes: early recognition of adverse effects and avoidance of disruptive false alarms

Corresponding to the uncontrolled diabetes pandemic, significant effort has been invested in developing new therapeutic options. Nevertheless, all medicines have possible adverse effects. Recently, a trend of 'scrutinizing' novel hypoglycaemic drug side effects based on scant scientific data has emerged. With recent publications highlighting possible dangers of rosiglitazone, insulin glargine, sitagliptin, exenatide and, most recently, pioglitazone, it seems that all means are valid and that every database is suitable, even if specifically defined as inadequate for the purpose of data analysis. The use of such data may lead authors to draw erroneous conclusions that may be granted unwarranted impact upon publication in leading scientific journals and eventually lead patients and misinformed physicians to wrongly change beneficial medication regimes. Adherence to strict scientific methodology, ongoing large clinical trials and creating adjudicated patient databases may facilitate early recognition of adverse effects while avoiding disruptive false alarms.

The human GLP-1 analog liraglutide and the pancreas: evidence for the absence of structural pancreatic changes in three species

Glucagon-like peptide (GLP)-1 analogs have been implicated as a risk factor for pancreatitis in humans. We investigated whether liraglutide, the once-daily human GLP-1 analog, induces pancreatitis in rats, mice, and monkeys. Pancreata from mice, rats, and nonhuman primates were examined macro- and microscopically. Evaluation of preneoplastic proliferative lesions in the pancreata from nonhuman primates was performed. After 2 years of treatment, 3 of 79 male mice in the control group and 2, 1, 1, and 1 mice in the different liraglutide groups (of 67-79 mice per group) had pancreatitis based on microscopic criteria. For females, the numbers were 0 of 79 mice in the control group and 3 mice in all the liraglutide groups (of 66-76 mice per group). Pancreatitis was not the cause of death in any animals. There were no cases of pancreatitis, macroscopically or microscopically, in 400 rats. Neither pancreatitis nor preneoplastic proliferative lesions was found in monkeys dosed for 87 weeks, with plasma liraglutide exposure 60-fold higher than that observed in humans at the maximal clinical dose. In conclusion, liraglutide did not induce pancreatitis in mice, rats, or monkeys when dosed for up to 2 years and at exposure levels up to 60 times higher than in humans.

[Benefits and risks of current pharmacotherapy in the treatment of type 2 diabetes]

The development of new drugs for the treatment of type 2 diabetes (T2DM) and metabolic disorders is currently one of the most innovative areas of drug development. However, a considerable number of newly developed drugs have either not reached the market and were stopped late in development or have been withdrawn after initial approval soon after market authorization due to serious safety concerns. How can drug safety problems be anticipated and, even more important, how can adverse events definitely caused by a drug be differentiated from incidences of naturally occurring diseases? This review article will provide an update about the state of the art treatment of type 2 diabetes and reflect on the newest available study evidence on glitazones, incretin mimetics (GLP-1 agonists and DPP-4 inhibitors), SGLT-2 inhibitors (gliflocines) and pan-PPAR agonists (glitazars). Furthermore, new and still experimental approaches for the treatment of T2DM, such as bardoxolone, salsalate and anakinra will be briefly reviewed.

Vildagliptin-induced acute pancreatitis

OBJECTIVE

To describe the first reported case of acute pancreatitis in a patient receiving vildagliptin.

METHODS

We present the clinical, biochemical, and radiographic findings of the study patient.

RESULTS

A 61-year-old woman who presented with severe abdominal pain was found to have acute pancreatitis. This occurred 5 weeks after the commencement of vildagliptin, a dipeptidyl-peptidase 4 inhibitor, for the treatment of type 2 diabetes mellitus. The patient's pancreatic enzymes were elevated (amylase, 1205 U/L; lipase, 8846 U/L), and abdominal computed tomography demonstrated diffuse pancreatic swelling, cyst formation, and necrosis in the body of the pancreas. In the absence of an identifiable cause for the patient's pancreatitis, vildagliptin was considered a potential trigger. The patient recovered after vildagliptin therapy was ceased.

CONCLUSIONS

Although incretin-based therapy effectively treats type 2 diabetes mellitus, emerging reports of acute pancreatitis in patients receiving sitagliptin and exenatide have prompted the US Food and Drug Administration to issue an alert on these drugs. This appears to be the first reported case of acute pancreatitis in a patient receiving vildagliptin, and it supports the possibility that acute pancreatitis may be a rare effect of incretin-based therapy.

Safety of dipeptidyl peptidase-4 inhibitors: a meta-analysis of randomized clinical trials

OBJECTIVE

Dipeptidyl peptidase-4 inhibitors (DPP4i) have been recently associated with increased risk of pancreatitis and cancer. The aim of the present meta-analysis of randomized clinical trials is the assessment of the effect of DPP4i on the incidence of major cardiovascular events (MACE), cancer, and pancreatitis.

RESEARCH DESIGN AND METHODS

An extensive Medline and Embase search for 'vildagliptin', 'sitagliptin', 'saxagliptin', 'alogliptin', 'linagliptin', and 'dutogliptin' was performed, collecting all randomized clinical trials on humans up to March 1, 2011. The present meta-analysis was therefore performed including all randomized clinical trials with a duration of at least 24 weeks, enrolling patients with type 2 diabetes, comparing DPP4i with either placebo or active drugs. Completed but still unpublished trials were identified through a search of www.clinicaltrials.gov, Food and Drug Administration, and European Medicines Agency website.

RESULTS

Fifty-three trials enrolling 20,312 and 13,569 patients for DPP4i and comparators, respectively, were included, reporting 176 malignancies, 257 MACE, and 22 pancreatitis. DPP4i, compared with placebo or other treatment, were associated with a similar risk of cancer (MH-OR 1.020 [0.742-1.402]; p = 0.90) and pancreatitis (0.786 [0.357-1.734], p = 0.55), and with a reduced risk of MACE (MH-OR 0.689 [0.528-0.899], p = 0.006).

CONCLUSIONS

The present meta-analysis seems to exclude any relevant short term effect of DPP4i on the incidence of cancer and suggest a possible protection from cardiovascular events. This result should be interpreted with caution, as those events were not the principal endpoint, the trial duration was short, and the characteristics of patients included could be different from routine clinical practice.

Skp2 is required for incretin hormone-mediated β-cell proliferation

The glucoincretin hormone glucagon-like peptide-1 (GLP-1) and its analog exendin-4 (Ex-4) promote β-cell growth and expansion. Here we report an essential role for Skp2, a substrate recognition component of SCF (Skp, Cullin, F-box) ubiquitin ligase, in promoting glucoincretin-induced β-cell proliferation by regulating the cellular abundance of p27. In vitro, GLP-1 treatment increases Skp2 levels, which accelerates p27 degradation, whereas in vivo, loss of Skp2 prevents glucoincretin-induced β-cell proliferation. Using inhibitors of phosphatidylinositol 3-kinase and Irs2 silencing RNA, we also show that the effects of GLP-1 in facilitating Skp2-dependent p27 degradation are mediated via the Irs2-phosphatidylinositol-3 kinase pathway. Finally, we show that down-regulation of p27 occurs in islets from aged mice and humans, although in these islets, age-dependent accumulation of p16(Ink4a) prevent glucoincretin-induced β-cell proliferation; however, ductal cell proliferation is maintained. Taken together, these data highlight a critical role for Skp2 in glucoincretin-induced β-cell proliferation.

A cohort study of acute pancreatitis in relation to exenatide use

AIM

Reports of acute pancreatitis associated with exenatide treatment prompted this study to estimate the association between acute pancreatitis and exenatide use relative to other antihyperglycaemic drugs.

METHODS

This cohort study included patients without claims for prior pancreatic disease who initiated exenatide or other antihyperglycaemic drugs between June 2005 and December 2007. Acute pancreatitis was identified with diagnosis codes and confirmed through review of blinded medical records. Poisson regression models provided estimates of rate ratios (RRs) and 95% confidence intervals (CIs) comparing the rate of acute pancreatitis during periods of current (days supplied + 31 days), recent (current definition + 31 days) and past use (≥32 days beyond current definition) of exenatide relative to other antihyperglycaemic drugs, adjusted for propensity scores. A prespecified nested case-control analysis provided RR estimates adjusted for patient characteristics abstracted from medical records.

RESULTS

Initiators of exenatide (N = 25719) had more baseline claims for obesity and concomitant diabetes drugs than comparators (N = 234536). There were 40 confirmed cases of acute pancreatitis in the exenatide cohort and 254 among other antihyperglycaemic drug initiators. Compared to other antihyperglycaemic drugs, the propensity score-adjusted RR for exenatide was 0.5 (95% CI 0.2-0.9) for current use, 1.1 (95% CI 0.4-3.2) for recent use and 2.8 (95% CI 1.6-4.7) for past use. The case-control analysis resulted in a RR of 0.2 for current use (95% CI 0.0-1.4) and 0.1 for recent use (95% CI 0.0-1.3), but an attenuated RR in the past use association (RR 1.1; 95% CI 0.1-11.0).

CONCLUSIONS

Exenatide use was not associated with an increased risk of acute pancreatitis.

Activation of the GLP-1 receptor signalling pathway: a relevant strategy to repair a deficient beta-cell mass

Recent preclinical studies in rodent models of diabetes suggest that exogenous GLP-1R agonists and DPP-4 inhibitors have the ability to increase islet mass and preserve beta-cell function, by immediate reactivation of beta-cell glucose competence, as well as enhanced beta-cell proliferation and neogenesis and promotion of beta-cell survival. These effects have tremendous implication in the treatment of T2D because they directly address one of the basic defects in T2D, that is, beta-cell failure. In human diabetes, however, evidence that the GLP-1-based drugs alter the course of beta-cell function remains to be found. Several questions surrounding the risks and benefits of GLP-1-based therapy for the diabetic beta-cell mass are discussed in this review and require further investigation.

A novel human-based receptor antagonist of sustained action reveals body weight control by endogenous GLP-1

Ex-4 (9-39)a is a well characterized GLP-1 receptor antagonist that suffers from two notable limitations, its nonhuman amino acid sequence and its relatively short in vivo duration of action. Comparable N-terminal shortening of human GLP-1 lessens agonism but does not provide a high potency antagonist. Through a series of GLP-1/Ex-4 hybrid peptides, the minimal structural changes required to generate a pure GLP-1-based antagonist were identified as Glu16, Val19, and Arg20, yielding an antagonist of approximately 3-fold greater in vitro potency compared with Ex-4 (9-39)a. The structural basis of antagonism appears to result from stabilization of the α helix combined with enhanced electrostatic and hydrophobic interactions with the extracellular domain of the receptor. Site-specific acylation of the human-based antagonist yielded a peptide of increased potency as a GLP-1 receptor antagonist and 10-fold greater selectivity relative to the GIP receptor. The acylated antagonist demonstrated sufficient duration of action to maintain inhibitory activity when administered as a daily subcutaneous injection. The sustained pharmacokinetics and enhanced human sequence combine to form an antagonist optimized for clinical study. Daily administration of this antagonist by subcutaneous injection to diet-induced obese mice for 1 week caused a significant increase in food intake, body weight, and glucose intolerance, demonstrating endogenous GLP-1 as a relevant hormone in mammalian energy balance in the obese state.

Pharmacological management of type 2 diabetes: the potential of incretin-based therapies

Management guidelines recommend metformin as the first-line therapy for most patients with type 2 diabetes uncontrolled by diet and exercise. Efficacy with metformin therapy is usually of limited duration, which necessitates the early introduction of one or two additional oral agents or the initiation of injections, glucagon-like peptide-1 (GLP-1) agonists or insulin. Although safe and effective, metformin monotherapy has been associated with gastrointestinal side effects (≈20% of treated patients in randomized studies) and is contraindicated in patients with renal insufficiency or severe liver disease. Patients treated with a sulphonylurea are at increased risk for hypoglycaemia and moderate weight gain, whereas those receiving a thiazolidinedione are subject to an increased risk of weight gain, oedema, heart failure or fracture. Weight gain and hypoglycaemia are associated with insulin use. Thus, there is an unmet need for a safe and efficacious add-on agent after initial-therapy failure. Evidence suggests that incretin-based agents, such as GLP-1 receptor agonists and dipeptidyl peptidase-4 inhibitors, can successfully achieve glycaemic targets and potentially provide cardiovascular and β-cell-function benefits. This review will examine current approaches for treating type 2 diabetes and discuss the place of incretin therapies, mainly GLP-1 agonists, in the type 2 diabetes treatment spectrum.

Exenatide does not evoke pancreatitis and attenuates chemically induced pancreatitis in normal and diabetic rodents

The risk of developing pancreatitis is elevated in type 2 diabetes and obesity. Cases of pancreatitis have been reported in type 2 diabetes patients treated with GLP-1 (GLP-1R) receptor agonists. To examine whether the GLP-1R agonist exenatide potentially induces or modulates pancreatitis, the effect of exenatide was evaluated in normal or diabetic rodents. Normal and diabetic rats received a single exenatide dose (0.072, 0.24, and 0.72 nmol/kg) or vehicle. Diabetic ob/ob or HF-STZ mice were infused with exenatide (1.2 and 7.2 nmol·kg(-1)·day(-1)) or vehicle for 4 wk. Post-exenatide treatment, pancreatitis was induced with caerulein (CRN) or sodium taurocholate (ST), and changes in plasma amylase and lipase were measured. In ob/ob mice, plasma cytokines (IL-1β, IL-2, IL-6, MCP-1, IFNγ, and TNFα) and pancreatitis-associated genes were assessed. Pancreata were weighed and examined histologically. Exenatide treatment alone did not modify plasma amylase or lipase in any models tested. Exenatide attenuated CRN-induced release of amylase and lipase in normal rats and ob/ob mice but did not modify the response to ST infusion. Plasma cytokines and pancreatic weight were unaffected by exenatide. Exenatide upregulated Reg3b but not Il6, Ccl2, Nfkb1, or Vamp8 expression. Histological analysis revealed that the highest doses of exenatide decreased CRN- or ST-induced acute inflammation, vacuolation, and acinar single cell necrosis in mice and rats, respectively. Ductal cell proliferation rates were low and similar across all groups of ob/ob mice. In conclusion, exenatide did not modify plasma amylase and lipase concentrations in rodents without pancreatitis and improved chemically induced pancreatitis in normal and diabetic rodents.

Acute pancreatitis in type 2 diabetes treated with exenatide or sitagliptin: a retrospective observational pharmacy claims analysis

OBJECTIVE

Cases of acute pancreatitis have been reported in association with exenatide, sitagliptin, and type 2 diabetes without use of these medications. It remains unknown whether exenatide or sitagliptin increase the risk of acute pancreatitis.

RESEARCH DESIGN AND METHODS

A retrospective cohort study of a large medical and pharmacy claims database was performed. Data for 786,656 patients were analyzed. Cox proportional hazard models were built to compare the risk of acute pancreatitis between diabetic and nondiabetic subjects and between exenatide, sitagliptin, and control diabetes medication use.

RESULTS

Incidence of acute pancreatitis in the nondiabetic control group, diabetic control group, exenatide group, and sitagliptin group was 1.9, 5.6, 5.7, and 5.6 cases per 1,000 patient years, respectively. The risk of acute pancreatitis was significantly higher in the combined diabetic groups than in the nondiabetic control group (adjusted hazard ratio 2.1 [95% CI 1.7-2.5]). Risk of acute pancreatitis was similar in the exenatide versus diabetic control group (0.9 [0.6-1.5]) and sitagliptin versus diabetic control group (1.0 [0.7-1.3]).

CONCLUSIONS

Our study demonstrated increased incidence of acute pancreatitis in diabetic versus nondiabetic patients but did not find an association between the use of exenatide or sitagliptin and acute pancreatitis. The limitations of this observational claims-based analysis cannot exclude the possibility of an increased risk.

Molecular and cellular mechanisms of pancreatic injury

PURPOSE OF REVIEW

This review focuses on studies from the past year that highlight molecular and cellular mechanisms of pancreatic injury arising from acute and chronic pancreatitis.

RECENT FINDINGS

Factors that induce or ameliorate injury as well as cellular pathways involved have been examined. Causative or sensitizing factors include refluxed bile acids, hypercalcemia, ethanol, hypertriglyceridemia, and acidosis. In addition, the diabetes drug exendin-4 has been associated with pancreatitis, whereas other drugs may reduce pancreatic injury. The intracellular events that influence disease severity are better understood. Cathepsin-L promotes injury through an antiapoptotic effect, rather than by trypsinogen activation. In addition, specific trypsinogen mutations lead to trypsinogen misfolding, endoplasmic reticulum stress, and injury. Endogenous trypsin inhibitors and upregulation of proteins including Bcl-2, fibroblast growth factor 21, and activated protein C can reduce injury. Immune cells, however, have been shown to increase injury via an antiapoptotic effect.

SUMMARY

The current findings are critical to understanding how causative factors initiate downstream cellular events resulting in pancreatic injury. Such knowledge will aid in the development of targeted treatments for pancreatitis. This review will first discuss factors influencing pancreatic injury, and then conclude with studies detailing the cellular mechanisms involved.

Effects of sitagliptin treatment on dysmetabolism, inflammation, and oxidative stress in an animal model of type 2 diabetes (ZDF rat)

The purpose of this paper is to evaluate the chronic effect of sitagliptin on metabolic profile, inflammation, and redox status in the Zucker Diabetic Fatty (ZDF) rat, an animal model of obese type 2 diabetes. Diabetic and obese ZDF (fa/fa) rats and their controls (ZDF +/+) were treated during 6 weeks with vehicle (control) and sitagliptin (10 mg/kg/bw). Glucose, HbA1c, insulin, Total-c, TGs, IL-1beta, TNF-alpha, CRPhs, and adiponectin were assessed in serum and MDA and TAS in serum, pancreas, and heart. Pancreatic histology was also evaluated. Sitagliptin in diabetic rats promoted a decrease in glucose, HbA1c, Total-c, and TGs accompanied by a partial prevention of insulinopenia, together, with a decrease in CRPhs and IL-1beta. Sitagliptin also showed a positive impact on lipid peroxidation and hypertension prevention. In conclusion, chronic sitagliptin treatment corrected the glycaemic dysmetabolism, hypertriglyceridaemia, inflammation, and hypertension, reduced the severity of the histopathological lesions of pancreatic endocrine and exocrine tissues, together with a favourable redox status, which might be a further advantage in the management of diabetes and its proatherogenic comorbidities.

Algorithm for the treatment of type 2 diabetes: a position statement of Brazilian Diabetes Society

The Brazilian Diabetes Society is starting an innovative project of quantitative assessment of medical arguments of and implementing a new way of elaborating SBD Position Statements. The final aim of this particular project is to propose a new Brazilian algorithm for the treatment of type 2 diabetes, based on the opinions of endocrinologists surveyed from a poll conducted on the Brazilian Diabetes Society website regarding the latest algorithm proposed by American Diabetes Association /European Association for the Study of Diabetes, published in January 2009.An additional source used, as a basis for the new algorithm, was to assess the acceptability of controversial arguments published in international literature, through a panel of renowned Brazilian specialists. Thirty controversial arguments in diabetes have been selected with their respective references, where each argument was assessed and scored according to its acceptability level and personal conviction of each member of the evaluation panel.This methodology was adapted using a similar approach to the one adopted in the recent position statement by the American College of Cardiology on coronary revascularization, of which not only cardiologists took part, but also specialists of other related areas.

Sitagliptin: review of preclinical and clinical data regarding incidence of pancreatitis

Recent case reports of acute pancreatitis in patients with type 2 diabetes (T2DM) treated with incretin-based therapies have triggered interest regarding the possibility of a mechanism-based association between pancreatitis and glucagon-like peptide-1 mimetics or dipeptidyl peptidase-4 (DPP-4) inhibitors. The objective of this review was to describe the controlled preclinical and clinical trial data regarding the incidence of pancreatitis with sitagliptin, the first DPP-4 inhibitor approved for use in patients with T2DM. Tissue samples from multiple animal species treated with sitagliptin for up to 2 years at plasma exposures substantially in excess of human exposure were evaluated to determine whether any potential gross or histomorphological changes suggestive of pancreatitis occurred. Sections were prepared by routine methods, stained with haematoxylin and eosin and examined microscopically. A pooled analysis of 19 controlled clinical trials, comprising 10,246 patients with T2DM treated for up to 2 years, was performed using patient-level data from each study for the evaluation of clinical and laboratory adverse events. Adverse events were encoded using the Medical Dictionary for Regulatory Activities (MedDRA) version 12.0 system. Incidences of adverse events were adjusted for patient exposure. Tissue samples from preclinical studies in multiple animal species did not reveal any evidence of treatment-related pancreatitis. The pooled analysis of controlled clinical trials revealed similar incidence rates of pancreatitis in patients treated with sitagliptin compared with those not treated with sitagliptin (0.08 events per 100 patient-years vs. 0.10 events per 100 patient-years, respectively). Preclinical and clinical trial data with sitagliptin to date do not indicate an increased risk of pancreatitis in patients with T2DM treated with sitagliptin.

Minireview: update on incretin biology: focus on glucagon-like peptide-1

The incretin hormone, glucagon-like peptide-1 (GLP-1), is now being used in the clinic to enhance insulin secretion and reduce body weight in patients with type 2 diabetes. Although much is already known about the biology of GLP-1, much remains to be understood. Hence, this review will consider recent findings related to the potential for enhancing endogenous levels of GLP-1 through selective use of secretagogues and the beneficial cardiovascular, neuroprotective, and immunomodulatory effects of GLP-1, as well as the possible effects of GLP-1 to enhance beta-cell growth and/or to induce pancreatitis or thyroid cancer. Finally, the potential for molecular medicine to enhance the success of GLP-1 therapy in the clinic is considered. A better understanding of the fundamental biology of GLP-1 may lead to new therapeutic modalities for the clinical use of this intestinal hormone.

Sitagliptin: review of preclinical and clinical data regarding incidence of pancreatitis

Recent case reports of acute pancreatitis in patients with type 2 diabetes (T2DM) treated with incretin-based therapies have triggered interest regarding the possibility of a mechanism-based association between pancreatitis and glucagon-like peptide-1 mimetics or dipeptidyl peptidase-4 (DPP-4) inhibitors. The objective of this review was to describe the controlled preclinical and clinical trial data regarding the incidence of pancreatitis with sitagliptin, the first DPP-4 inhibitor approved for use in patients with T2DM. Tissue samples from multiple animal species treated with sitagliptin for up to 2 years at plasma exposures substantially in excess of human exposure were evaluated to determine whether any potential gross or histomorphological changes suggestive of pancreatitis occurred. Sections were prepared by routine methods, stained with haematoxylin and eosin and examined microscopically. A pooled analysis of 19 controlled clinical trials, comprising 10,246 patients with T2DM treated for up to 2 years, was performed using patient-level data from each study for the evaluation of clinical and laboratory adverse events. Adverse events were encoded using the Medical Dictionary for Regulatory Activities (MedDRA) version 12.0 system. Incidences of adverse events were adjusted for patient exposure. Tissue samples from preclinical studies in multiple animal species did not reveal any evidence of treatment-related pancreatitis. The pooled analysis of controlled clinical trials revealed similar incidence rates of pancreatitis in patients treated with sitagliptin compared with those not treated with sitagliptin (0.08 events per 100 patient-years vs. 0.10 events per 100 patient-years, respectively). Preclinical and clinical trial data with sitagliptin to date do not indicate an increased risk of pancreatitis in patients with T2DM treated with sitagliptin.

Association of pancreatitis with glucagon-like peptide-1 agonist use

OBJECTIVE

To review the possible association between glucagon-like peptide-1 (GLP-1) agonist use and pancreatitis in patients with type 2 diabetes mellitus.

DATA SOURCES

A MEDLINE search (1950-January 2010) identified key clinical trials delineating adverse effects associated with GLP-1 agonist use. Key search terms included type 2 diabetes mellitus, pancreatitis, incretins, exenatide, liraglutide, albiglutide, and taspoglutide. Review of references listed in the articles identified was also performed. The Food and Drug Administration (FDA) Web site and Amylin Pharmaceuticals file data were utilized to extract case report information and unpublished clinical development data related to GLP-1 agonist use and pancreatitis.

STUDY SELECTION AND DATA EXTRACTION

Phase 2 and 3 clinical trials evaluating exenatide, liraglutide, albiglutide, and taspoglutide that discussed treatmentrelated adverse effects as well as FDA-reviewed case reports of pancreatitis in patients taking these same therapies were included. One study evaluating type 2 diabetes as a risk factor for development of acute pancreatitis was also included. Exenatide case reports and clinical development data were also included.

DATA SYNTHESIS

Currently there have been 8 cases during clinical development and 36 postmarketing reports of acute pancreatitis in exenatide-treated patients. Four patients have developed acute (n = 3) or chronic (1) pancreatitis during liraglutide clinical trials. There have been no reports to date of development of acute pancreatitis in patients taking albiglutide or taspoglutide.

CONCLUSIONS

Observational reports and clinical trial data suggest an association between GLP-1 agonist use and acute pancreatitis; however, additional clinical trial data and in-depth case report analysis are needed to further evaluate and verify this finding.