A physiologic and pharmacological basis for implementation of incretin hormones in the treatment of type 2 diabetes mellitus

The Risk and Predictors of Malignancies in Ankylosing Spondylitis Patients in Israel-A Retrospective Electronic Data-Based Study

BACKGROUND

Previous studies demonstrated unclear and vast variability in the association between Ankylosing Spondylitis (AS) and the risk of cancer.

OBJECTIVES

To assess the risk of overall and site-specific malignancies for AS patients in Israel, while examining the role of comorbidities and immunomodulatory therapy.

METHODS

We conducted a retrospective electronic data-based study including all AS patients diagnosed between 2002 and 2018, with no history of cancer prior to enrollment, with 5:1 ratio matched-control by age, gender, and place of residence. The odds Ratios (OR) for site-specific malignancies, comparing AS patients and controls, were calculated using logistic regression. Risk factors for malignancies within the AS cohort were evaluated in the same manner.

RESULTS

This study comprised 5825 AS patients and 28,356 matched controls. There was a higher overall risk of cancer in AS patients compared to controls (OR = 1.4, 95% CI 1.24-1.6), specifically for solid malignancies (OR = 1.5, 95% CI 1.3-1.7), CNS (OR = 3.72, 95% CI 1.29-10.7), kidney (OR = 2.06, 95% CI 1.12-3.8), and malignancy of unknown primary (OR = 3.06, 95% CI 2.35-3.98). Regarding predictors for malignancy within AS patients, older age at diagnosis (OR = 1.31, 95%,CI 1.25-2.36), diabetes (OR = 1.52, 95% CI 1.18-1.97), IBD (OR = 2.61, 95% CI 1.75-3.89), and treatment with DMARDs (OR = 2.17, 95% CI 1.65-2.83) were associated with a higher risk of solid malignancies, while NSAIDs treatment alone had a protective effect for solid malignancies (OR = 0.78, 95% CI 0.61-0.99). No significant association was found between anti-TNF therapy and the risk of solid or hematologic malignancies within the AS group.

CONCLUSION

AS is associated with an increased risk of overall and site-specific malignancies, with independently higher risk for older age, comorbidity of DM, IBD, and treatment with DMARDs.

Hypoglycemic Effect of Electroacupuncture at ST25 Through Neural Regulation of the Pancreatic Intrinsic Nervous System

Electroacupuncture (EA) is considered to have potential antidiabetic effects; however, the role of the pancreatic intrinsic nervous system (PINS) in EA-induced amelioration of type 2 diabetes (T2DM) remains unclear. Therefore, we investigated whether EA at ST25 exerts any beneficial effects on insulin resistance (IR), inflammation severity, and pancreatic β cell function via the PINS in a rat model of a high-fat diet-streptozotocin (HFD/STZ)-induced diabetes. To this end, Sprague Dawley rats were fed with HFD to induce IR, followed by STZ (35 mg/kg, i.p.) injection to establish the T2DM model. After hyperglycemia was confirmed as fasting glucose level > 16.7 mmol/L, the rats were treated with EA (2 mA, 2/15 Hz) for the next 28 days. Model rats showed increased serum glucose, insulin, IR, and TNF-α levels with a concomitant decrease in β cell function. Microscopy examination of the pancreas revealed pathological changes in islets, which reverted to near-normal levels after EA at ST25. EA improved islet cell morphology by increasing islet area and reducing vacuolation. EA at ST25 decreased transient receptor potential vanilloid 1 (TRPV1) and increased substance P (SP) and calcitonin gene-related peptide (CGRP) expression. Subsequently, insulin secretion decreased and impaired pancreatic endocrine function was restored through the TRPV1 channel (SP/CGRP)-insulin circuit. EA increased choline acetyltransferase and neuropeptide Y expression and controlled inflammation. It also enhanced the cocaine and amphetamine-regulated transcript prepropeptide expression and promoted glucagon-like peptide-1 secretion. Additionally, the electrophysiological activity of PINS during acupuncture (2.71 ± 1.72 Hz) was significantly increased compared to the pre-acupuncture frequency (0.32 ± 0.37 Hz, P < 0.05). Thus, our study demonstrated the beneficial effect of EA on β cell dysfunction via the PINS in rat models of HFD-STZ-induced T2DM.

Dapagliflozin elevates plasma high-density lipoprotein levels and influences visceral fat gene expression in streptozotocin-induced diabetes mellitus

OBJECTIVES

Dapagliflozin (Dapa) could potentially be used to treat type 1 diabetes mellitus. We tested the hypothesis that it would influence blood lipid levels and visceral fat accumulation in a rodent diabetic model.

METHODS

We used three groups of male Wistar rats: Controls, streptozotocin (STZ)-treated rats and STZ-treated orally with Dapa (STZ+Dapa), 10 mg/kg/day for six weeks. Blood glucose and serum lipids levels were determined. Plasma levels of lipases (hormone-sensitive lipase, HSL and lipoprotein lipase, LPL), adipokines (leptin and adiponectin) and proinflammatory cytokines [tumour necrosis factor-alpha (TNFα) and interleukin-6 (IL-6)] were determined by ELISA assays. mRNA levels in the perirenal fat were determined by real-time PCR.

KEY FINDINGS

Dapa suppressed STZ-related hyperglycemia by 20% (P < 0.05) and increased serum HDL when compared to the controls and the STZ-only treated rats (both P < 0.05). STZ treatment caused elevations of other serum lipids that were resistant to Dapa treatment. Dapa treatment also increased both plasma and visceral fat mRNA levels of leptin, LPL and IL-6, while decreasing plasma and fat expressions of HSL and TNFα compared to the STZ-only treated rats (all P < 0.05).

CONCLUSIONS

Our results suggest that Dapa, in addition to its antidiabetic effect, also influences the function of adipose tissue which could be beneficial in the treatment of diabetes.

Clinical pharmacology of glucagon-like peptide-1 receptor agonists

Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are an important asset in the armamentarium for the treatment of type 2 diabetes mellitus (type 2 DM). Incretin failure is a critical etiopathogenetic feature of type 2 DM, which, if reversed, results in improved glycaemic control. GLP-1 RAs are injectable peptides that resemble the structure and function of endogenous incretin GLP-1, but as they are not deactivated by the dipeptidyl peptidase-4 (DPP-4), their half-life is prolonged compared with native GLP-1. Based on their ability to activate GLP-1 receptor, GLP-1 RAs are classified as short-acting (exenatide twice-daily and lixisenatide once-daily), and long-acting (liraglutide once-daily and the once-weekly formulations of exenatide extended-release, dulaglutide, and albiglutide). Semaglutide, another long-acting, once-weekly GLP-1 RA, was recently approved by the FDA and EMA. Although all of these agents potently reduce haemoglobin A1C (HbA1c), there are unique features and fundamental differences among them related to fasting and postprandial hyperglycaemia reduction, weight loss potency, cardiovascular protection efficacy, and adverse events profile. It is imperative that current evidence be integrated and applied in the context of an individualised patient-centred approach. This should include not only glucose management but also targeting as many as possible of the pathophysiologic mechanisms responsible for type 2 DM development and progression.

Use of Canagliflozin in Combination With and Compared to Incretin-Based Therapies in Type 2 Diabetes

In Brief Sodium-glucose cotransporter 2 (SGLT2) inhibitors and incretin-based therapies (dipeptidyl peptidase-4 [DPP-4] inhibitors and glucagon-like peptide-1 [GLP-1] receptor agonists) are widely used to treat patients with type 2 diabetes. In clinical and real-world studies, canagliflozin, an SGLT2 inhibitor, has demonstrated superior A1C lowering compared to the DPP-4 inhibitor sitagliptin. Canagliflozin can also promote modest weight/fat loss and blood pressure reduction. The addition of canagliflozin to treatment regimens that include a DPP-4 inhibitor or a GLP-1 receptor agonist has been shown to further improve glycemic control, while still maintaining beneficial effects on cardiometabolic parameters such as body weight and blood pressure. Overall, the available clinical and real-world evidence suggests that canagliflozin is a safe and well-tolerated treatment option that can be considered either in addition to or instead of incretin-based therapies for patients with type 2 diabetes.

Evidence-based practice use of quick-release bromocriptine across the natural history of type 2 diabetes mellitus

OBJECTIVES

To provide an evidence-based practice overview on the clinical use of bromocriptine-quick release (QR) across the natural history of type 2 diabetes mellitus (T2DM).

METHODS

Articles for inclusion were selected after a comprehensive literature search of English-language PubMed articles and identification of other relevant references through other sources. Inclusion criteria were animal studies examining the mechanism of action and efficacy of bromocriptine, and clinical studies examining the safety and efficacy of bromocriptine-QR in patients with T2DM, without a time limitation.

RESULTS

The brain plays a key role in total body metabolism, in particular ensuring that sufficient levels of glucose are available for proper neural functioning. The hypothalamic suprachiasmatic nucleus (SCN), the body's biological clock, plays a key role in the regulation of seasonal and diurnal variations of insulin sensitivity. A daily surge of dopaminergic activity in the SCN upon waking enables insulin sensitivity throughout the day. When this is disrupted (e.g. by a high fat/sugar diet, stress, altered [diminished] exercise, altered sleep/wake cycle, diabetes), insulin resistance persists throughout the day and overnight. Improving the morning surge in dopaminergic activity with the short-acting dopamine D2 receptor agonist bromocriptine-QR can safely and effectively improve glycemic control, while improving cardiovascular disease risk factors and related adverse events, and reducing sympathetic tone, as demonstrated by 5 reports of the Cycloset Safety Trial and 3 additional clinical studies of bromocriptine-QR.

CONCLUSIONS

In patients with T2DM, the dopamine D2 receptor agonist bromocriptine-QR has been shown to be well tolerated, efficacious, and a logical treatment option.

Contractile apparatus dysfunction early in the pathophysiology of diabetic cardiomyopathy

Diabetes mellitus significantly increases the risk of cardiovascular disease and heart failure in patients. Independent of hypertension and coronary artery disease, diabetes is associated with a specific cardiomyopathy, known as diabetic cardiomyopathy (DCM). Four decades of research in experimental animal models and advances in clinical imaging techniques suggest that DCM is a progressive disease, beginning early after the onset of type 1 and type 2 diabetes, ahead of left ventricular remodeling and overt diastolic dysfunction. Although the molecular pathogenesis of early DCM still remains largely unclear, activation of protein kinase C appears to be central in driving the oxidative stress dependent and independent pathways in the development of contractile dysfunction. Multiple subcellular alterations to the cardiomyocyte are now being highlighted as critical events in the early changes to the rate of force development, relaxation and stability under pathophysiological stresses. These changes include perturbed calcium handling, suppressed activity of aerobic energy producing enzymes, altered transcriptional and posttranslational modification of membrane and sarcomeric cytoskeletal proteins, reduced actin-myosin cross-bridge cycling and dynamics, and changed myofilament calcium sensitivity. In this review, we will present and discuss novel aspects of the molecular pathogenesis of early DCM, with a special focus on the sarcomeric contractile apparatus.

Saxagliptin add-on therapy to insulin with or without metformin for type 2 diabetes mellitus: 52-week safety and efficacy

BACKGROUND

Achievement of glycemic control is an important objective in the management of type 2 diabetes mellitus (T2DM).

OBJECTIVE

The objective of this study was to evaluate the safety and efficacy of the dipeptidyl peptidase-4 inhibitor saxagliptin versus placebo as add-on therapy in patients with T2DM inadequately controlled with insulin alone or insulin plus metformin.

METHODS

This was a long-term (28-week) extension of a short-term (24-week), randomized, double-blind, parallel-group trial of saxagliptin 5 mg once daily versus placebo as add-on therapy to open-label insulin or insulin plus metformin therapy totaling 52 weeks of treatment. In contrast with the goal of maintaining a stable insulin dosage during the short-term phase, during the extension phase the insulin dosage was flexible and adjusted as deemed appropriate by the investigator. The study was conducted in a clinical practice setting, including family practice and hospital sites. Patients with T2DM aged 18-78 years with glycated hemoglobin (HbA1c) 7.5-11 % on a stable insulin regimen (30-150 U/day with or without metformin) for ≥8 weeks at screening were included in the study. Patients were stratified by metformin use and randomly assigned 2:1 to oral saxagliptin 5 mg (n = 304) or placebo (n = 151) once daily. All patients who completed the initial 24 weeks of treatment were eligible to participate in the 28-week extension, regardless of whether they had required rescue treatment. The main outcome measure was change in HbA1c from baseline to week 52.

RESULTS

In general, the outcomes achieved at week 24 were sustained to week 52. Adjusted mean change from baseline HbA1c at week 52 was greater with saxagliptin (-0.75 %) versus placebo (-0.38 %); the adjusted between-group difference was -0.37 % (95 % CI -0.55 to -0.19); between-group differences were similar in patients treated with metformin (-0.37 % [95 % CI -0.59 to -0.15]) and without metformin (-0.37 % [95 % CI -0.69 to -0.04]). At week 52, a greater proportion of patients receiving saxagliptin achieved HbA1c <7 % than those receiving placebo (21.3 vs. 8.7 %; between-group difference 12.6 % [95 % CI 6.1-19.1]). The increase from baseline in mean total daily insulin dose at week 52 was numerically smaller with saxagliptin (5.67 vs 6.67 U with placebo; difference, -1.01 U [95 % CI -3.24 to 1.22]). During the 52-week study period, the proportion of patients reporting ≥1 adverse event (AE) was 66.4 % with saxagliptin and 71.5 % with placebo, the majority being mild or moderate in intensity. The most common AEs (≥5 % with saxagliptin or placebo) were urinary tract infection, nasopharyngitis, upper respiratory tract infection, headache, influenza, and pain in extremity; the incidence of each AE was similar between treatment groups. In the saxagliptin and placebo groups, the incidence of reported hypoglycemia was 22.7 and 26.5 %, respectively; the incidence of confirmed hypoglycemia (fingerstick glucose ≤50 mg/dL [≤2.77 mmol/L] with characteristic symptoms) was 7.6 and 6.6 %, respectively. Adjusted mean change from baseline body weight was +0.8 kg with saxagliptin and +0.5 kg with placebo.

CONCLUSION

Saxagliptin 5 mg once daily as add-on to insulin, with or without concomitant metformin, produced a durable improvement in glycemic control and was well tolerated over 52 weeks of treatment.

Ankylosing spondylitis and other inflammatory spondyloarthritis increase the risk of developing type 2 diabetes in an Asian population

This study evaluated whether people with ankylosing spondylitis (AS) and spondyloarthritis are at higher risk of type 2 diabetes mellitus (T2DM). We used a sub-dataset of the National Health Insurance Research Database from 1996 to 2010 to established a AS cohort consisting new patients with AS or spondyloarthritis (N = 7,778) and a non-AS cohort without the diseases (N = 31,112). Incidences of T2DM in the two cohorts, hazard ratios (HRs) of risk of T2DM in association with AS, and cumulative probability of having T2DM were estimated by the end of 2010. The incidence of T2DM was 1.17-fold higher in the AS cohort than in the non-AS cohort (13.5 vs. 11.5, per 1,000 person-years), with an adjusted HR of 1.16 (95 % CI = 1.05-1.29). The T2DM incidence was higher for women than for men; while the Cox model measured sex-specific adjusted HR of T2DM was higher for men than for women. The incidence rate of T2DM increased with age in both cohorts, while the age-specific measures showed that the adjusted HR of T2DM was higher in young AS patients (≤50 years of age) than older ones, compared to their peers of non-AS group. The plot of Kaplan-Meier analysis showed that the overall probability of having T2DM was 2 % higher in the AS cohort than in the non-AS cohort (log-rank test: p < 0.0001). Patients with AS and spondyloarthritis have an increased risk of developing T2DM.

Choice of early treatment regimen and impact on β-cell preservation in type 2 diabetes

The progressive deterioration of glycaemic control in individuals with type 2 diabetes mellitus (T2DM) results from insulin resistance combined with the ongoing loss of β-cell function. Although it had been suggested that most β-cell dysfunction occurs after the development of T2DM, studies have documented a substantial early loss of β-cell function, particularly during the prediabetic state. In patients diagnosed with T2DM, β-cell function continues to decline despite treatment with commonly prescribed antihyperglycaemic medications, and ultimately exogenous insulin administration is required to maintain optimal glycaemic control. Thus, interventions to address the early decline in β-cell function could potentially alter the course of T2DM, preventing or delaying its onset and decreasing the incidence of complications. Original research and review articles on this topic were identified in a PubMed search from January 2000 through August 2012. Data from prospective studies and clinical trials suggest that lifestyle modifications and certain antihyperglycaemic medications, including thiazolidinediones (TZDs), glucagon-like peptide-1 (GLP-1) agonists, dipeptidyl peptidase-4 (DPP-4) inhibitors and insulin, may preserve or enhance β-cell function. The implication of current data is that early initiation of lifestyle modifications and antihyperglycaemic agents that preserve β-cell function might reverse or delay progression to T2DM in those with prediabetes. Moreover, improved β-cell function may confer more durable glucose control and perhaps reduce/delay the incidence of diabetic complications. Long-term studies are needed to validate this hypothesis.

Clinically relevant reductions in HbA1c without hypoglycaemia: results across four studies of saxagliptin

BACKGROUND

In four 24-week controlled studies, the antihyperglycaemic efficacy of saxagliptin was demonstrated in patients with type 2 diabetes mellitus as add-on therapy to glyburide, a thiazolidinedione, or metformin, and when used in initial combination with metformin vs. metformin monotherapy in drug-naive patients.

METHODS

Data from these studies were analysed to compare the proportions of patients who achieved specific reductions from baseline in glycated haemoglobin [HbA(1c); reductions of ≥ 0.5% and ≥ 0.7% in all studies (prespecified); reductions ≥ 1.0% in the add-on studies and ≥ 1.0% to ≥ 2.5% in the initial combination study (post hoc)] for saxagliptin vs. comparator at week 24. We report overall rates of glycaemic response defined by these reductions in HbA(1c) and rates of response without experiencing hypoglycaemia.

RESULTS

Large glycaemic response rates were higher with saxagliptin 2.5 and 5 mg/day than with comparator (HbA(1c) ≥ 1.0%, 31.7-50.3% vs. 10.3-20.0%) as add-on therapy and higher with saxagliptin 5 mg/day as initial combination with metformin than with metformin monotherapy (HbA(1c) ≥ 2.0%, 68.3% vs. 49.8%) in drug-naive patients. Addition of saxagliptin was associated with a low incidence of hypoglycaemia; overall response rates and response rates excluding patients who experienced hypoglycaemia were similar. Analysis of several demographic and baseline clinical variables revealed no consistent correlations with response to saxagliptin.

CONCLUSIONS

Whether receiving saxagliptin as an add-on therapy to glyburide, a thiazolidinedione, or metformin or in initial combination with metformin, a greater percentage of patients achieve clinically relevant large reductions in HbA(1c) vs. comparator, with a low incidence of hypoglycaemia.

Ultra-high-performance liquid chromatography for the determination of exenatide in monkey plasma by tandem quadrupole mass spectrometry

A highly sensitive ultra-high-performance liquid chromatographic-tandem mass spectrometry (UPLC/MS/MS) method was developed for the quantification of the synthetic peptide drug of exenatide in monkey plasma. Sample preparation was carried out by solid-phase extraction (SPE), and bivalirudin was used as the internal standard (IS). An excellent chromatographic separation was obtained on a reversed-phase C18 column with a gradient elution. Detection utilized a Qtrap 5500 system operated in the positive ion mode with multiple reaction monitoring (MRM). The proposed method was validated by assessing the specificity, linearity, intra- and inter-day precision and accuracy, recovery, and stability. The method resulted in a linear calibration range of 0.10-30 ng/mL, extracting with only 50 μL monkey plasma aliquots. The intra- and inter-day precisions (as relative standard deviation) were less than 7.5% and 9.6%, respectively. The method could be successfully utilized for the pharmacokinetic study of exenatide in monkeys following a single subcutaneous injection of Byetta.

Effects of saxagliptin and sitagliptin on glycaemic control and pancreatic β-cell mass in a streptozotocin-induced mouse model of type 2 diabetes

AIMS

We examined the effects of the oral dipeptidyl peptidase-4 (DPP-4) inhibitor saxagliptin on glycaemic control and pancreatic β-cell mass and morphology in a mouse model of type 2 diabetes mellitus (T2DM).

METHODS

Male C57BL/6 mice (n = 12/group) aged 4 to 6 weeks and weighing >15 g received a high-fat diet throughout this 45-day study. After a 7-day handling period, baseline levels of plasma glucose, plasma insulin and glycated haemoglobin (HbA1c) were assessed. Animals were allocated to one of six groups: compound vehicle control, intraperitoneal streptozotocin (STZ, 50 mg/kg)-treated control and saxagliptin (10 mg/kg) or sitagliptin (10 mg/kg, positive control) initiated 7 days before or 1 day after STZ administration. Endpoints included changes in body weight, food and water consumption, glucose tolerance (approximately 3 weeks post-STZ), fasting glucose and HbA1c and immunohistochemical analyses of the pancreas.

RESULTS

Body weight, weight gain and food intake were reduced in STZ versus control mice. DPP-4 inhibitor treatment did not affect these changes, but the increase in water intake observed post-STZ administration was significantly attenuated with DPP-4 inhibitors whether initiated before or after STZ injury. Small but significant improvements in glycaemic control were observed with DPP-4 inhibitors versus the STZ control. Improved β-cell mass and morphology were observed with saxagliptin given pre- or post-STZ and sitagliptin given post-STZ.

CONCLUSIONS

Saxagliptin mitigated damage to β-cells and improved glycaemic control in this mouse model of T2DM.

Tendinopathy and Inflammation: Some Truths

Overuse tendinopathies are a common cause of pain and disability in athletes. According to histological findings, it is a “failed healing response” to overuse tendon injury. In obesity, macrophages and mast cells migrate to adipose tissue, and the resulting decreased availability of immune circulating cells should be responsible for less effective immune responses to acute tendon injury. In diabetic patients, free glucose molecules attach to collagen, alter collagen solubility, increase resistance to enzymatic degradation, and impair cross linking, contributing to the subsequent development of chronic tendinopathy secondary to a failed healing response to a tendon insult. Prolonged systemic, low-grade inflammation and impaired insulin sensitivity act as a risk factor for a “failed healing response” after an acute tendon insult, and predispose to the development of chronic overuse tendinopathies. Further studies may reveal novel therapeutic treatment approaches.