Efficacy of glimepiride on insulin resistance, adipocytokines, and atherosclerosis

Uncoupling hepatic insulin resistance - hepatic inflammation to improve insulin sensitivity and to prevent impaired metabolism-associated fatty liver disease in type 2 diabetes

Diabetes mellitus is a metabolic disease clinically-characterized as acute and chronic hyperglycemia. It is emerging as one of the common conditions associated with incident liver disease in the US. The mechanism by which diabetes drives liver disease has become an intense topic of discussion and a highly sought-after therapeutic target. Insulin resistance (IR) appears early in the progression of type 2 diabetes (T2D), particularly in obese individuals. One of the co-morbid conditions of obesity-associated diabetes that is on the rise globally is referred to as non-alcoholic fatty liver disease (NAFLD). IR is one of a number of known and suspected mechanism that underlie the progression of NAFLD which concurrently exhibits hepatic inflammation, particularly enriched in cells of the innate arm of the immune system. In this review we focus on the known mechanisms that are suspected to play a role in the cause-effect relationship between hepatic IR and hepatic inflammation and its role in the progression of T2D-associated NAFLD. Uncoupling hepatic IR/hepatic inflammation may break an intra-hepatic vicious cycle, facilitating the attenuation or prevention of NAFLD with a concurrent restoration of physiologic glycemic control. As part of this review, we therefore also assess the potential of a number of existing and emerging therapeutic interventions that can target both conditions simultaneously as treatment options to break this cycle.

Insulin resistance and insulin sensitizing agents

Insulin resistance is a common feature of obesity and type 2 diabetes, but novel approaches of diabetes subtyping (clustering) revealed variable degrees of insulin resistance in people with diabetes. Specifically, the severe insulin resistant diabetes (SIRD) subtype not only exhibits metabolic abnormalities, but also bears a higher risk for cardiovascular, renal and hepatic comorbidities. In humans, insulin resistance comprises dysfunctional adipose tissue, lipotoxic insulin signaling followed by glucotoxicity, oxidative stress and low-grade inflammation. Recent studies show that aside from metabolites (free fatty acids, amino acids) and signaling proteins (myokines, adipokines, hepatokines) also exosomes with their cargo (proteins, mRNA and microRNA) contribute to altered crosstalk between skeletal muscle, liver and adipose tissue during the development of insulin resistance. Reduction of fat mass mainly, but not exclusively, explains the success of lifestyle modification and bariatric surgery to improve insulin sensitivity. Moreover, some older antihyperglycemic drugs (metformin, thiazolidinediones), but also novel therapeutic concepts (new peroxisome proliferator-activated receptor agonists, incretin mimetics, sodium glucose cotransporter inhibitors, modulators of energy metabolism) can directly or indirectly reduce insulin resistance. This review summarizes molecular mechanisms underlying insulin resistance including the roles of exosomes and microRNAs, as well as strategies for the management of insulin resistance in humans.

Effect of glycemic control on markers of subclinical atherosclerosis in patients with type 2 diabetes mellitus: A review

Cardiovascular disease is the predominant cause of death in type 2 diabetes mellitus (T2DM). Evidence suggests a strong association between duration and degree of hyperglycemia and vascular disease. However, large trials failed to show cardiovascular benefit after intensive glycemic control, especially in patients with longer diabetes duration. Atherosclerosis is a chronic and progressive disease, with a long asymptomatic phase. Subclinical atherosclerosis, which is impaired in T2DM, includes impaired vasodilation, increased coronary artery calcification (CAC), carotid intima media thickness, arterial stiffness, and reduced arterial elasticity. Each of these alterations is represented by a marker of subclinical atherosclerosis, offering a cost-effective alternative compared to classic cardiac imaging. Their additional use on top of traditional risk assessment strengthens the predictive risk for developing coronary artery disease (CAD). We, herein, review the existing literature on the effect of glycemic control on each of these markers separately. Effective glycemic control, especially in earlier stages of the disease, attenuates progression of structural markers like intima-media thickness and CAC. Functional markers are improved after use of newer anti-diabetic agents, such as incretin-based treatments or sodium-glucose co-transporter-2 inhibitors, especially in T2DM patients with shorter disease duration. Larger prospective trials are needed to enhance causal inferences of glycemic control on clinical endpoints of CAD.

Sulfonylureas may be useful for glycemic management in patients with diabetes and liver cirrhosis

This study aimed to investigate the long-term outcomes of sulfonylurea (SU) use in patients with T2DM and compensated liver cirrhosis. From January 1, 2000, to December 31, 2012, we selected the data of 3781 propensity-score-matched SU users and nonusers from Taiwan’s National Health Insurance Research Database. The mean follow-up time for this study was 5.74 years. Cox proportional hazards models with robust sandwich standard error estimates were used to compare the risks of main outcomes between SU users and nonusers. The incidence of mortality during follow-up was 3.24 and 4.09 per 100 person-years for SU users and nonusers, respectively. The adjusted hazard ratios and 95% confidence intervals for all-cause mortality, major cardiovascular events, and decompensated cirrhosis in SU users relative to SU nonusers were 0.79 (0.71–0.88), 0.69 (0.61–0.80), and 0.82 (0.66–1.03), respectively. The SU-associated lower risks of death and cardiovascular events seemed to have a dose–response trend. This population-based cohort study demonstrated that SU use was associated with lower risks of death and major cardiovascular events compared with SU non-use in patients with T2DM and compensated liver cirrhosis. SUs may be useful for glycemic management for patients with liver cirrhosis.

Diabetes and calcification: The potential role of anti-diabetic drugs on vascular calcification regression

Vascular calcification (VC) has been well-established as an independent and strong predictor of cardiovascular diseases (CVD) as well as major cardiac adverse events (MACE). VC is associated with increased mortality in patients with CVD. Pathologically, VC is now believed to be a multi-directional active process ultimately resulting in ectopic calcium deposition in vascular beds. On the other hand, prevalence of diabetes mellitus (DM) is gradually increasing thus making the current population more prone to future CVD. Although the mechanisms involved in development and progression of VC in DM patients are not fully understood, a series of evidences demonstrated positive association between DM and VC. It has been highlighted that different cellular pathways are involved in this process. These intermediates such as tumor necrosis factor alpha (TNF-α), various interleukins (ILs) and different cell-signaling pathways are over-expressed in DM patients leading to development of VC. Thus, considering the burden and significance of VC it is of great importance to find a therapeutic approach to prevent or minimize the development of VC in DM patients. Over the past few years various anti diabetic drugs (ADDs) have been introduced and many of them showed desired glucose control. But no study demonstrated the effects of these medications on regression of VC. In this review, we will briefly discuss the current understanding on DM and VC and how commonly used ADDs modulate the development or progression of VC.

The differential influence of glimepiride and glibenclamide on insulin resistance and adiponectin levels in patients with type 2 diabetes

Several studies have demonstrated the decreased insulin resistance (IR) in persons with type 2 diabetes mellitus (T2DM) treated with glimepiride. Those suggest this might be associated with observed higher concentrations of adiponectin. We assessed if there is a difference in IR and metabolic syndrome components between glimepiride and glibenclamide treatment as well as adiponectin concentration in T2DM. Our research observed 20 T2DM patients treated with glibenclamid and 20 switched to glimepiride (n = 20) treatment for 24 weeks. Anthropometric measurements and laboratory analysis were performed at the beginning and at the end of treatment while IR was accessed by homeostasis model assessment of insulin resistance (HOMA-IR). The glimepiride group revealed better glycaemic control compared to glibenclamide group. Moreover, the adiponectin concentration increased (23.9 ± 17.3 to 29.1 ± 12.2 ng/mL, p = 0.087) whereas it decreased in the glibenclamide group (34.3 ± 22.6 to 20.3 ± 11.3 ng/mL, p = 0.011) following 24 weeks of treatment. The serum adiponectin and HOMA-IR were inversely correlated within the group of glibenclamide (r = -0.667, p = 0.009). The present study demonstrates that glimepiride might have beneficial effect on IR compared to glibenclamide, as suggested. However, this observation needs further study investigation among other formulations of SU.

Glucocrinology of Modern Sulfonylureas: Clinical Evidence and Practice-Based Opinion from an International Expert Group

AIM

The primary objective of this document is to develop practice-based expert group opinion on certain important but less discussed endocrine and metabolic effects of modern sulfonylureas (SUs) and their usage in the management of diabetes mellitus (DM).

BACKGROUND

Modern SUs may be considered a panacea in DM care with their beneficial extra-pancreatic, pleiotropic, and cardiovascular effects. Safe glycemic control with SUs could be achieved with appropriate patient selection, drug and dosage selection, and patient empowerment. Additionally, sulfonylureas also exhibit certain endocrine and metabolic effects, which could be considered beneficial in the management of DM. In this regard, a group of international clinical experts discussed the less known beneficial aspects of SUs and safe and smart prescription of modern SUs in DM care.

RESULTS

The concept of glucocrinology or the relationship of glycemia with the endocrine system was emphasized during the meetings. Clinical experts arrived at a consensus for the usage of modern SUs in the presence of other endocrine dysfunction and the impact of these drugs on endocrine health. The beneficial pleiotropic and cardiovascular effects of modern SUs were also discussed. The key discussion points were considered to develop clinical expert opinions for the use of modern SUs in persons with DM. Clinical expert opinions were developed for indications, pleiotropic benefits, cardiovascular outcomes, adherence, and safe use of modern SUs.

CONCLUSIONS

Appropriate clinical judgement coupled with a patient-centered approach is crucial to achieve the best outcome in persons with DM. Owing to their safety, efficacy, extra-pancreatic benefits including effects on endocrine and metabolic aspects, and low cost of therapy, modern SUs could be considered as drugs/agents of choice for the treatment of diabetes.

FUNDING

Sanofi India.

Efficacy and Safety of Premixed Human Insulin Combined with Sulfonylureas in Type 2 Diabetic Patients Previously Poorly Controlled with Insulin

INTRODUCTION

Some type 2 diabetes (T2DM) patients treated with premixed insulin alone or in combination with oral glucose-lowering agents (without sulfonylureas) cannot reach the required glucose targets. Clinical studies have demonstrated that diabetes patients treated with sulfonylureas achieve stable glycemic control, with a low hypoglycemic rate. The aim of our study was to evaluate the efficacy and safety of therapy with the combination of premixed insulin and sulfonylureas.

METHODS

A total of 120 patients with T2DM who were unable to achieve glycemic control on premixed human insulin were randomized into four groups, namely, a control group (premixed human insulin only) and three groups receiving combination therapy with premixed human insulin and one of the following sulfonylureas: gliclazide sustained release tablets [Diamicron], glipizide extended release tablets [Glucotrol XL], and glimepiride medium-to-long-acting tablets [Amaryl], with 30 patients in each group. Hemoglobin A1c, blood glucose, and adverse events were assessed at baseline and at the end of the 12-week treatment period.

RESULTS

After treatment for 12 weeks, HbA1c, fasting glucose, and 2-h postprandial glucose levels in the four groups were significantly decreased when compared with baseline (P < 0.05). However, there was no difference between the four groups at the end of the study. In the control group, the daily insulin dose had been significantly increased at the end of the follow-up when compared with baseline (P  < 0.05), while there were no significant changes in premixed insulin dose in the three combination therapy groups. There were no significant differences in adverse events among the four groups.

CONCLUSION

Insulin combined with sulfonylureas could improve glycemic control without increasing daily insulin dose and adverse events. Based on our results, we consider the combination of premixed insulin and sulfonylureas to be effective and safe for the treatment of T2DM.

TRIAL REGISTRATION

This trial was registered as ChiCTR-TRC-14004751. Trial Registration Date: 5 June 2014.

Comparison of the Brachial-ankle Pulse Wave Velocity between Patients with Acute Coronary Syndrome and Effort Angina Pectoris

Objective Coronary artery disease (CAD) is one of the clinical categories of atherosclerotic diseases. There have been reports indicating that the pathological findings of coronary artery plaque differ between acute coronary syndrome (ACS) and effort angina pectoris (EAP). The brachial-ankle pulse wave velocity (baPWV) has been reported to be a good indicator of atherosclerotic disease. However, the baPWV may not be equally effective for evaluating ACS and EAP. In this study, we compared the baPWV in patients with ACS and those with EAP. Methods Two hundred and seventy patients were enrolled in this study. All patients underwent coronary angiography, and were separated into normal (CONT), ACS and EAP groups according to the clinical and coronary angiographic findings. The baPWV was evaluated and the results were compared among the groups. Results The baPWV was significantly higher in the EAP group than in the other groups. The baPWV in the ACS group was almost the same as that of the CONT group and was significantly higher in the EAP group than in the ACS group across almost all age groups. Conclusion The present study showed that the baPWV is high in patients with EAP. In contrast, the baPWV in the ACS group was almost normal and was similar to that of the CONT group. ACS occurs due to plaque rupture induced by atherosis, which may occur independent of sclerosis in the coronary artery. EAP may occur in proportion to systemic arterial sclerosis. The baPWV is suitable for screening for EAP, but not for ACS.

Pharmacologic Differences of Sulfonylureas and the Risk of Adverse Cardiovascular and Hypoglycemic Events

OBJECTIVE

Sulfonylureas have been associated with an increased risk of cardiovascular adverse events and hypoglycemia, but it is unclear if these risks vary with different agents. We assessed whether the risks of acute myocardial infarction, ischemic stroke, cardiovascular death, all-cause mortality, and severe hypoglycemia differ between sulfonylureas grouped according to pancreas specificity and duration of action.

RESEARCH DESIGN AND METHODS

Using the U.K. Clinical Practice Research Datalink, linked with the Hospital Episodes Statistics and the Office for National Statistics databases, we conducted a cohort study among patients with type 2 diabetes initiating monotherapy with sulfonylureas between 1998 and 2013. Adjusted hazard ratios (HRs) and 95% CIs were estimated using Cox proportional hazards models, comparing use of pancreas-nonspecific, long-acting sulfonylureas (glyburide/glimepiride) to pancreas-specific, short-acting sulfonylureas (gliclazide/glipizide/tolbutamide).

RESULTS

The cohort included 17,604 sulfonylurea initiators (mean [SD] follow-up 1.2 [1.5] years). Compared with specific, short-acting sulfonylureas (15,741 initiators), nonspecific, long-acting sulfonylureas (1,863 initiators) were not associated with an increased risk of acute myocardial infarction (HR 0.86; CI 0.55-1.34), ischemic stroke (HR 0.92; CI 0.59-1.45), cardiovascular death (HR 1.01; CI 0.72-1.40), or all-cause mortality (HR 0.81; CI 0.66-1.003), but with an increased risk of severe hypoglycemia (HR 2.83; CI 1.64-4.88).

CONCLUSIONS

The nonspecific, long-acting sulfonylureas glyburide and glimepiride do not have an increased risk of cardiovascular adverse events compared with the specific, short-acting sulfonylureas gliclazide, glipizide, and tolbutamide. However, nonspecific, long-acting sulfonylureas glyburide and glimepiride have an increased risk of severe hypoglycemia.

Insulin use, adipokine profiles and breast cancer prognosis

BACKGROUND

Type-2 diabetes mellitus (T2DM) and breast cancer (BC) share common cytokine signaling changes resultant from adipose tissue dysfunction. This modified adipokine signaling was shown to be directly associated with changes in the body mass index (BMI) and diet and it is expected to also be influenced by T2DM pharmacotherapy. We evaluated the relationship between pre-existing diabetes treatment, circulating adipokine levels at cancer diagnosis, and long-term outcomes.

METHODS

All incident BC cases were reviewed (01/01/2003-12/31/2009, N=2194). Each of the subjects with baseline T2DM (cases) was matched with two other subjects without T2DM (controls) based on the following criteria: age, BMI, ethnicity, menopausal status and tumor stage. All cases and controls with available baseline plasma and tumor biopsies, and being surgery and BC treatment naïve, were included (N₁=97, N₂=194). Clinical history and vital status were documented. Adipokine levels (adiponectin, leptin, TNF-α, CRP, IL-1β, IL-1Ra, IL-6, and C-peptide) were assessed by either ELISA or Luminex® assays. Cancer outcomes were assessed by Kaplan-Meier analysis; associations between categorical variables were assessed by Fisher's exact test, categorical and continuous variables by Kruskal-Wallis or Wilcoxon Rank-Sum test, where appropriate. Multivariate adjustments (MVP, multivariate p-value) were performed accounting for age, tumor stage, BMI, estrogen receptor (ER) status and cumulative comorbidity. All biomarker correlations were assessed by the Pearson method. Utilization of insulin and insulin secretagogues was associated with ER (-) phenotype (p=0.008, p=0.043) and poorer BC outcomes (p=0.012, p=0.033). Insulin users were found to have lower C-peptide and higher IL-6, TNF-α and CRP levels, of which elevated CRP and TNF-α were associated with poorer BC outcomes (p=0.003, MVP=0.210). Insulin remarked by higher leptin levels as compared to controls (p=0.052), but did not differ significantly from non-users. Although lower adiponectin levels were observed among non-insulin users as compared to controls (p<0.001, MVP=0.006), insulin use seemed to have restored adiponectin production. C-peptide levels were lower among insulin users as compared to non-users (p<0.001, MVP<0.001) and approached levels comparable with those of the controls. In the overall dataset, C-peptide lower than 0.75ng/ml were strongly associated with poorer survival (p=0.007, MVP=0.002). Among insulin users, C-peptide levels were inversely correlated with IL-1β and IL-1Ra levels only after full adjustment (p=0.012, p=0.030); the correlation was unremarkable in other groups.

CONCLUSION

Insulin use is associated with elevated leptin, CRP, TNFα, and lower C-peptide and also linked to poor BC outcomes. More research is needed to verify these findings; however, we are among the first to correlate pharmacotherapy use, measures of adipose tissue dysfunction and cancer outcomes.

Diabetes medications: Impact on inflammation and wound healing

Chronic wounds are a common complication in patients with diabetes that often lead to amputation. These non-healing wounds are described as being stuck in a persistent inflammatory state characterized by accumulation of pro-inflammatory macrophages, cytokines and proteases. Some medications approved for management of type 2 diabetes have demonstrated anti-inflammatory properties independent of their marketed insulinotropic effects and thus have underappreciated potential to promote wound healing. In this review, the potential for insulin, metformin, specific sulfonylureas, thiazolidinediones, and dipeptidyl peptidase-4 inhibitors to promote healing is evaluated by reviewing human and animal studies on inflammation and wound healing. The available evidence indicates that diabetic medications have potential to prevent wounds from becoming arrested in the inflammatory stage of healing and to promote wound healing by downregulating pro-inflammatory cytokines, upregulating growth factors, lowering matrix metalloproteinases, stimulating angiogenesis, and increasing epithelization. However, no clinical recommendations currently exist on the potential for specific diabetic medications to impact healing of chronic wounds. Thus, we encourage further research that may guide physicians on providing personalized diabetes treatments that achieve glycemic goals while promoting healing in patients with chronic wounds.

Possible effects of glimepiride beyond glycemic control in patients with type 2 diabetes: a preliminary report

Background

The purpose of this study was to elucidate the effects of glimepiride on the levels of biomarkers related to cardiovascular regulation in patients with type 2 diabetes mellitus.

Methods and results

Thirty-four patients with type 2 diabetes received glimepiride for 24 weeks. Significant decreases in the levels of glyceraldehyde-derived advanced glycation end products, (glycer-AGE: toxic AGE), eotaxin and fibroblast growth factor (FGF)-2 were recognized after the administration of glimepiride. Moreover, there were trends for there to be increases in the levels of granulocyte-colony stimulating factor (G-CSF) and granulocyte macrophage-colony stimulating factor (GM-CSF), and decreases in the levels of fractalkine, soluble CD40 ligand (sCD40L), macrophage inflammatory protein (MIP)-β, vascular endothelial growth factor (VEGF) and soluble receptor for AGE (sRAGE).

Conclusions

Glimepiride may have potent anti-oxidative, anti-inflammatory and angiogenic properties and it may potentially repair tissue damage by decreasing the levels of toxic AGE and increasing colony-stimulating factors.

Renal and vascular protective effects of ezetimibe in chronic kidney disease

OBJECTIVE

Dyslipidemia is a risk factor for not only cardiovascular diseases (CVD), but also chronic kidney disease (CKD). Ezetimibe, a cholesterol absorption inhibitor, lowers cholesterol levels by inhibiting both extrinsic and intrinsic cholesterol absorption via the gastrointestinal duct. However, very few studies have examined its efficacy and safety for patients with dyslipidemia complicated with CKD.

METHODS

Thirty-seven dyslipidemic patients (low density lipoprotein cholesterol (LDL-C) levels ≥120 mg/dL) complicated with CKD were given ezetimibe (10 mg/day) for twenty-four weeks. The efficacy and safety of the therapy, including the anti-atherosclerotic and renal protective effects, were then examined.

RESULTS

Significant decreases were observed in the levels of LDL-C (158.9 ± 26.9 mg/dL→123.0 ± 31.8 mg/dL; p<0.0001), remnant-like lipoprotein cholesterol (9.3 ± 5.3 mg/dL→7.3 ± 3.8 mg/dL; p<0.05) and lipoprotein (a) (22.0 ± 16.1 mg/dL→16.4 ± 11.0 mg/dL; p<0.01). The estimated glomerular filtration rate did not change, but the urine protein to creatinine ratio decreased significantly (1,107.3 ± 1,454.2 mg/gCre→732.1 ± 1,237.8 mg/gCre; p<0.05). No changes were observed in the carotid intima media thickness, but the brachial-ankle pulse wave velocity decreased significantly (1,770.4 ± 590.3 cm/sec→1,702.5 ± 519.9 cm/sec; p<0.05). No adverse events were observed.

CONCLUSION

Ezetimibe can be safely administered even to patients with CKD. The results of this study indicate that ezetimibe may provide some renal protection and suppress the complications of CVD in CKD patients.

Transcriptomic analysis of insulin-sensitive tissues from anti-diabetic drug treated ZDF rats, a T2DM animal model

Gene expression changes have been associated with type 2 diabetes mellitus (T2DM); however, the alterations are not fully understood. We investigated the effects of anti-diabetic drugs on gene expression in Zucker diabetic fatty (ZDF) rats using oligonucleotide microarray technology to identify gene expression changes occurring in T2DM. Global gene expression in the pancreas, adipose tissue, skeletal muscle, and liver was profiled from Zucker lean control (ZLC) and anti-diabetic drug treated ZDF rats compared with those in ZDF rats. We showed that anti-diabetic drugs regulate the expression of a large number of genes. We provided a more integrated view of the diabetic changes by examining the gene expression networks. The resulting sub-networks allowed us to identify several biological processes that were significantly enriched by the anti-diabetic drug treatment, including oxidative phosphorylation (OXPHOS), systemic lupus erythematous, and the chemokine signaling pathway. Among them, we found that white adipose tissue from ZDF rats showed decreased expression of a set of OXPHOS genes that were normalized by rosiglitazone treatment accompanied by rescued blood glucose levels. In conclusion, we suggest that alterations in OXPHOS gene expression in white adipose tissue may play a role in the pathogenesis and drug mediated recovery of T2DM through a comprehensive gene expression network study after multi-drug treatment of ZDF rats.

Up- and down-regulation of adiponectin expression and multimerization: mechanisms and therapeutic implication

Adiponectin has been receiving a great deal of attention due to its potential therapeutic use for metabolic and cardiovascular disorders. Adiponectin expression levels and multimerization are down-regulated in obesity and up-regulated by insulin sensitizers such as thiazolidinediones (TZDs), metformin, sulfonylurea and resveratrol (RSV). The precise mechanisms underlying adiponectin up- and down-regulation remain largely unknown, but recent studies indicate that the cellular and plasma levels of adiponectin could be regulated at both transcriptional and post-transcriptional levels. At the post-translational level, TZDs and resveratrol promote adiponectin levels and multimerization via up-regulation of disulfide-bond-A oxidoreductase-like protein (DsbA-L). Adiponectin levels are also stimulated by FOXO1 and AMP-activated protein kinase (AMPK), and are suppressed by PKA or silencing mediator of retinoid and thyroid hormone receptors (SMRT). Since multimerization is important not only for adiponectin function but also for stability, increasing adiponectin multimerization has become a promising drug target for the treatment of metabolic diseases and other related disorders.

Variations in tissue selectivity amongst insulin secretagogues: a systematic review

AIM

Insulin secretagogues promote insulin release by binding to sulfonylurea receptors on pancreatic β-cells (SUR1). However, these drugs also bind to receptor isoforms on cardiac myocytes (SUR2A) and vascular smooth muscle (SUR2B). Binding to SUR2A/SUR2B may inhibit ischaemic preconditioning, an endogenous protective mechanism enabling cardiac tissue to survive periods of ischaemia. This study was designed to identify insulin secretagogues that selectively bind to SUR1 when given at therapeutic doses.

METHODS

Using accepted systematic review methods, three electronic databases were searched from inception to 13 June 2011. Original studies measuring the half-maximal inhibitory concentration (IC(50)) for an insulin secretagogue on K(ATP) channels using standard electrophysiological techniques were included. Steady-state concentrations (C(SS)) were estimated from the usual oral dose and clearance values for each drug.

RESULTS

Data were extracted from 27 studies meeting all inclusion criteria. IC(50) values for SUR1 were below those for SUR2A/SUR2B for all insulin secretagogues and addition of C(SS) values identified three distinct patterns. The C(SS) for gliclazide, glipizide, mitiglinide and nateglinide lie between IC(50) values for SUR1 and SUR2A/SUR2B, suggesting that these drugs bind selectively to pancreatic receptors. The C(SS) for glimepiride and glyburide (glibenclamide) was above IC(50) values for all three isoforms, suggesting these drugs are non-selective. Tolbutamide and repaglinide may have partial pancreatic receptor selectivity because IC(50) values for SUR1 and SUR2A/SUR2B overlapped somewhat, with the C(SS) in the midst of these values.

CONCLUSIONS

Insulin secretagogues display different tissue selectivity characteristics at therapeutic doses. This may translate into different levels of cardiovascular risk.

Reduced cell proliferation and neuroblast differentiation in the dentate gyrus of high fat diet-fed mice are ameliorated by metformin and glimepiride treatment

We investigated the effects of a high-fat diet (HFD) and the subsequent treatment of metformin (met) and glimepiride (glim), which are widely prescribed for type 2 diabetes, on cell proliferation and neuroblast differentiation using Ki67 and doublecortin (DCX) immunohistochemistry, respectively. Animals were fed low-fat diet (LFD) or HFD for 8 weeks. After 5 weeks of the HFD treatment, met alone or met + glim was administered orally once a day for 3 weeks. Body weight and food intake were much higher in the HFD + vehicle-treated group than the LFD-treated group. The administration of met or met + glim to the HFD-treated group resulted in a decrease in weight gain and food intake. Ki67-immunoreactive ((+)) nuclei, DCX(+) neuroblasts and brain-derived neurotrophic factor (BDNF) protein levels were markedly decreased in the dentate gyrus (DG) of the HFD + vehicle-treated group compared to the LFD-treated group. The administration of met or met + glim to the HFD-treated group prevented the reduction of Ki67(+) nuclei, DCX(+) neuroblasts, BDNF levels in the DG. The intraventricular injection of K252a (a BDNF receptor blocker) to the HFD-treated group treated met or met + glim distinctively lowered the reduction of cell proliferation and neuroblast differentiation induced by HFD. These results suggest that a HFD significantly reduces cell proliferation and neuroblast differentiation by reducing BDNF levels and these effects are ameliorated by treatment with met or met + glim.

Effects of glimepiride and glibenclamide on carotid atherosclerosis in type 2 diabetic patients

We performed a 3-year observation study of type 2 diabetic patients treated with glibenclamide or glimepiride and found that the annual progression of the maximum carotid intima-media thickness was significantly attenuated in the subjects treated with glimepiride (n=20) as compared with those treated with glibenclamide (n=20) (-0.044±0.171 mm/year vs. 0.077±0.203 mm/year, p=0.0474).

Therapies for type 2 diabetes: lowering HbA1c and associated cardiovascular risk factors

OBJECTIVES

To summarize data supporting the effects of antidiabetes agents on glucose control and cardiovascular risk factors in patients with type 2 diabetes.

METHODS

Studies reporting on the effects of antidiabetes agents on glycemic control, body weight, lipid levels, and blood pressure parameters are reviewed and summarized for the purpose of selecting optimal therapeutic regimens for patients with type 2 diabetes.

RESULTS

National guidelines recommend the aggressive management of cardiovascular risk factors in patients with type 2 diabetes, including weight loss and achieving lipid and blood pressure treatment goals. All antidiabetes pharmacotherapies lower glucose; however, effects on cardiovascular risk factors vary greatly among agents. While thiazolidinediones, sulfonylureas, and insulin are associated with weight gain, dipeptidyl peptidase-4 inhibitors are considered weight neutral and metformin can be weight neutral or associated with a small weight loss. Glucagon-like peptide-1 receptor agonists and amylinomimetics (e.g. pramlintide) result in weight loss. Additionally, metformin, thiazolidinediones, insulin, and glucagon-like peptide-1 receptor agonists have demonstrated beneficial effects on lipid and blood pressure parameters.

CONCLUSION

Management of the cardiovascular risk factors experienced by patients with type 2 diabetes requires a multidisciplinary approach with implementation of treatment strategies to achieve not only glycemic goals but to improve and/or correct the underlying cardiovascular risk factors.

Glucose supply and insulin demand dynamics of antidiabetic agents

BACKGROUND

For microvascular outcomes, there is compelling historical and contemporary evidence for intensive blood glucose reduction in patients with either type 1 diabetes mellitus (T1DM) or type 2 diabetes mellitus (T2DM). There is also strong evidence to support macrovascular benefit with intensive blood glucose reduction in T1DM. Similar evidence remains elusive for T2DM. Because cardiovascular outcome trials utilizing conventional algorithms to attain intensive blood glucose reduction have not demonstrated superiority to less aggressive blood glucose reduction (Action to Control Cardiovascular Risk in Diabetes; Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation; and Veterans Affairs Diabetes Trial), it should be considered that the means by which the blood glucose is reduced may be as important as the actual blood glucose.

METHODS

By identifying quantitative differences between antidiabetic agents on carbohydrate exposure (CE), hepatic glucose uptake (HGU), hepatic gluconeogenesis (GNG), insulin resistance (IR), peripheral glucose uptake (PGU), and peripheral insulin exposure (PIE), we created a pharmacokinetic/pharmacodynamic model to characterize the effect of the agents on the glucose supply and insulin demand dynamic. Glucose supply was defined as the cumulative percentage decrease in CE, increase in HGU, decrease in GNG, and decrease in IR, while insulin demand was defined as the cumulative percentage increase in PIE and PGU. With the glucose supply and insulin demand effects of each antidiabetic agent summated, the glucose supply (numerator) was divided by the insulin demand (denominator) to create a value representative of the glucose supply and insulin demand dynamic (SD ratio).

RESULTS

Alpha-glucosidase inhibitors (1.25), metformin (2.20), and thiazolidinediones (TZDs; 1.25-1.32) demonstrate a greater effect on glucose supply (SD ratio >1), while secretagogues (0.69-0.81), basal insulins (0.77-0.79), and bolus insulins (0.62-0.67) demonstrate a greater effect on insulin demand (SD ratio <1).

CONCLUSION

Alpha-glucosidase inhibitors, metformin, and TZDs demonstrate a greater effect on glucose supply, while secretagogues, basal insulin, and bolus insulin demonstrate a greater effect on insulin demand. Because T2DM cardiovascular outcome trials have not demonstrated macrovascular benefit with more aggressive blood glucose reduction when using conventional algorithms that predominantly focus on insulin demand, it would appear logical to consider a model that incorporates both the extent of blood glucose lowering (hemoglobin A1c) and the means by which the blood glucose was reduced (SD ratio) when considering macrovascular outcomes.

Association of exogenous insulin or sulphonylurea treatment with an increased incidence of hepatoma in patients with hepatitis C virus infection

BACKGROUND

Diabetes mellitus is frequently seen in hepatitis C patients and is often treated with antidiabetic agents that increase serum insulin levels. Because insulin is a growth-promoting hormone, antidiabetic agents could pose a risk for hepatocellular carcinoma (HCC).

AIM

The aim of this study was to investigate an association between antidiabetic therapies and the incidence of HCC in hepatitis C patients with diabetes mellitus.

METHODS

A nested case-control study was conducted. Participants were recruited from a cohort study, in which patients with hepatitis C were consecutively registered. Participants were assigned to an HCC group (n=138) or a non-HCC group (n=103). To identify independent factors, variables including use of antidiabetic agents were analysed by logistic regression analysis.

RESULTS

Besides ageing, being male, cirrhosis and hypoalbuminaemia, use of exogenous insulin and a second-generation sulphonylurea were significant independent factors associated with an incidence of HCC [odds ratio (OR) 2.969, 95% confidence interval (CI) 1.293-6.819, P<0.0103 and OR 6.831, 95% CI 1.954-23.881, P<0.0026 respectively). In stratified analyses, the impact of these antidiabetic agents was more evident in patients who were non-cirrhotic than in those who were cirrhotic.

CONCLUSIONS

Exogenous insulin and a second-generation sulphonylurea were independent variables associated with an incidence of HCC in hepatitis C patients with diabetes mellitus. This association was evident in patients who were non-cirrhotic. To verify a causal relationship between these antidiabetic agents and the development of HCC, a prospective cohort study is required.

Relationship between job strain and radial arterial wave reflection in middle-aged male workers

OBJECTIVE

This study examined the relationship between job stain and radial arterial wave reflection as expressed by the augmentation index (AI), a marker of cardiovascular risk, in middle-aged male workers.

METHODS

Radial AI was measured using automated applanation tonometry in 808 working men (mean age; 47+/-5 years) at a company in Kanagawa, Japan in 2007. An elevated AI represents the deterioration of arterial properties and increased cardiovascular risk. Job demand and job control (decision latitude) were evaluated by a self-administered, Brief Job Stress Questionnaire. High job strain was defined as the combination of high job demand and low job control.

RESULTS

In the entire study population, the mean+/-SD and the median of AI were 74+/-13% and 75%, respectively. High job strain was seen in 267 subjects. In a multiple logistic regression analysis with adjustment for multiple potential confounders, high job strain showed a significantly increased odds ratio (1.47, 95% CI; 1.04-2.09, P=0.029) for an elevated AI (> or =75%).

CONCLUSION

High job strain was significantly associated with an elevated radial AI. The measurement of AI may be useful when incorporated in workplace interventions to reduce the risk of cardiovascular disease, especially at sites where workers tend to perceive high job strain.

Switch to oral hypoglycemic agent therapy from insulin injection in patients with type 2 diabetes

AIM

We aimed to determine the feasibility of substituting thiazolidinedione-based therapy for insulin injection therapy in patients with type 2 diabetes.

METHODS

Thirty-six subjects (17 men and 19 women) aged 67.8 +/- 11.3 years with an average insulin dose of 0.46 +/- 0.17 U/kg bodyweight, a duration of insulin therapy of 6.1 +/- 8.2 years and an average hemoglobin A1c (HbA1c) of 6.8 +/- 1.3% were switched from insulin injection therapy to pioglitazone, glimepiride and voglibose combination therapy.

RESULTS

The number of subjects achieving HbA1c levels of less than 7% at 4 months was 30. The success rate of switch therapy was 83% (30/36). HbA1c was significantly reduced from 6.7 +/- 1.3% to 5.9 +/- 0.7% at 4 months after the switch (P < 0.01) in 32 patients who completed the planned 4-month study. No adverse effects including heart failure, liver dysfunction or severe hypoglycemia were observed. The insulin dose and the maximum blood glucose on the switch day were significantly lower and the age was significantly higher in the subjects who achieved HbA1c less than 7% at 4 months compared to those who did not (P < 0.05).

CONCLUSION

Thiazolidinedione-based oral combination therapy may efficiently and safely substitute relatively high-dose insulin injection therapy in patients with type 2 diabetes.

Serum adiponectin concentrations correlate with severity of rheumatoid arthritis evaluated by extent of joint destruction

Adiponectin is a hormone released by adipose tissue with antidiabetic, antiatherogenic, and anti-inflammatory properties. The present observational study focused on the relation between serum adiponectin level and the disease severity of established rheumatoid arthritis (RA). Ninety patients with more than 5-year diagnosis of RA and 42 age- and BMI-matched control were enrolled. The severity of RA was evaluated according to the number of destructed joints of overall 68 joints on plain radiographs (37 patients had mild RA and 53 had severe RA). Serum adiponectin level was significantly higher in the severe RA group (17.7+/-6.7 microg/ml) than in the control (9.1+/-3.8 microg/ml) and mild RA groups (13.9+/-6.5 microg/ml) (control vs. mild RA group, P<0.001; mild RA vs. severe RA group, P<0.01). These results suggest that increased number of joint destruction is associated with hyperadiponectinemia in established RA patients.

Hydrogen peroxide-induced translocation of glycolipid-anchored (c)AMP-hydrolases to lipid droplets mediates inhibition of lipolysis in rat adipocytes

BACKGROUND

The insulin-independent inhibition of lipolysis by palmitate, the anti-diabetic sulphonylurea glimepiride and H2O2 in rat adipocytes involves stimulation of the glycosylphosphatidylinositol (GPI)-specific phospholipase-C (GPI-PLC) and subsequent translocation of the GPI-anchored membrane ectoproteins (GPI-proteins), Gce1 and cluster of differentiation antigen (CD73), from specialized plasma membrane microdomains (DIGs) to cytosolic lipid droplets (LDs). This results in cAMP degradation at the LD surface and failure to activate hormone-sensitive lipase. Reactive oxygen species (ROS) may trigger this sequence of events in response to palmitate and glimepiride.

EXPERIMENTAL APPROACH

The effects of various inhibitors of ROS production on the release of H2O2, GPI anchor cleavage and translocation of the photoaffinity-labelled or metabolically labelled Gce1 and CD73 from DIGs to LD and inhibition of lipolysis by different fatty acids and sulphonylureas were studied with primary rat adipocytes.

KEY RESULTS

Glimepiride and palmitate induced the production of H2O2 via the plasma membrane NADPH oxidase and mitochondrial complexes I and III, respectively. Inhibition of ROS production was accompanied by the loss of (i) GPI-PLC activation, (ii) Gce1 and CD73 translocation and (iii) lipolysis inhibition in response to palmitate and glimepiride. Non-metabolizable fatty acids and the sulphonylurea drug tolbutamide were inactive. NADPH oxidase and GPI-PLC activities colocalized at DIGs were stimulated by glimepiride but not tolbutamide.

CONCLUSIONS AND IMPLICATIONS

The data suggest that ROS mediate GPI-PLC activation at DIGs and subsequent GPI-protein translocation from DIGs to LD in adipocytes which leads to inhibition of lipolysis by palmitate and glimepiride. This insulin-independent anti-lipolytic mechanism may be engaged by future anti-diabetic drugs.

Pioglitazone plus glimepiride: a promising alternative in metabolic control

Current approaches to pharmacotherapy of type 2 diabetes focus on two key aspects of hyperglycaemia - insulin secretory dysfunction and insulin resistance. Combining drugs that target both these defects via different mechanisms of action improves long-term glycaemic control and offers a number of additional benefits. A fixed-dose combination of pioglitazone and glimepiride in a single tablet is now available in the US (Duetact(TM)). Both pioglitazone and glimepiride are glucose-lowering agents with distinct mechanisms of action. Pioglitazone is a potent and selective peroxisome proliferator-activated receptor-gamma agonist that improves whole-body insulin sensitivity and augments hepatic glucose uptake. On the other hand, glimepiride acts by releasing insulin from pancreatic beta-cells and improves both first and second phases of insulin secretion. These two therapies have been shown to act synergistically to treat type 2 diabetes - glimepiride therapy achieves rapid reductions in glycated haemaglobin (HbA(1c)), whereas pioglitazone sustains glycaemic control in the longer term. Furthermore, pioglitazone and glimepiride affect a number of pleiotropic markers. In particular, pioglitazone has beneficial effects on the atherogenic diabetic dyslipidaemia that are greater than those seen with rosiglitazone and other oral glucose-lowering agents. This advantage is also seen when comparing pioglitazone and rosiglitazone in combination with glimepiride. In addition, pioglitazone also improves a number of atherosclerotic risk markers that appear to translate into clinical benefits on macrovascular outcomes. Glimepiride may also improve several atherosclerotic risk markers and lipoproteins. This review discusses the potential benefits of combining pioglitazone plus glimepiride on patient compliance, targeting the dual effects of insulin resistance and beta-cell dysfunction and affecting a number of metabolic and cardiovascular parameters.

Effect of gliclazide modified release on adiponectin, interleukin-6, and tumor necrosis factor-alpha plasma levels in individuals with type 2 diabetes mellitus

OBJECTIVE

The aim of the study was to evaluate the effect of gliclazide modified release (MR) treatment on adiponectin, interleukin 6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha) plasma concentrations in type 2 diabetic patients.

RESEARCH DESIGN AND METHODS

24 randomly selected type 2 diabetic patients, aged 61.2 +/- 15.4 years, with poorly controlled glucose level (mean glycated hemoglobin [HbA1c] 7.6 +/- 1.1%) despite treatment with diet and/or oral hypoglycemic agents, were included in the study. All of the patients, after a 2-week run-in period, were given gliclazide MR for 12 weeks. At baseline, and after gliclazide MR treatment, HbA(1c) and plasma concentrations of IL-6, TNF-alpha, and adiponectin were measured.

RESULTS

Gliclazide MR treatment produced significant reductions in fasting plasma glucose (from 7.6 +/- 1.4 to 6.6 +/- 1.2 mmol/L, p < 0.01), HbA(1c) (from 7.6 +/- 1.1 to 6.9 +/- 0.8%, p < 0.01), and plasma IL-6 concentrations (from 2.5 +/- 1.8 to 1.8 +/- 1.2 pg/mL, p < 0.05). A significant increase in plasma adiponectin level was noted (from 6.4 +/- 3.3 to 7.6 +/- 4.4 mug/mL, p < 0.05). Plasma TNF-alpha concentrations and homeostasis model assessment of insulin resistance (HOMA-IR) decreased after treatment, but these changes did not reach statistical significance.

CONCLUSIONS

Gliclazide MR improves glycemic control and, in addition, has a positive influence on the plasma level of some inflammatory markers and adiponectin. Increased plasma adiponectin and decreased plasma IL-6, and TNF-alpha levels may explain, at least in part, the anti-atherogenic action of this drug reported elsewhere.