Heart failure: the frequent, forgotten, and often fatal complication of diabetes

Docosahexaenoic Acid Inhibits Vascular Smooth Muscle Cell Proliferation Induced by Glucose Variability

Background:

Vascular Smooth Muscle cells (VSMC) enact crucial roles in early vasculogenesis and sustenance of vascular integrity. However, aberrant proliferation of VSMC followed by migration into the blood vessel wall leads to the formation of vascular lesions accounting for the degeneration and remodelling of vascular basement membrane. In diabetes, hyperglycaemia accelerates VSMC proliferation and contributes to the initiation and progression of atherosclerotic lesions. Recently, acute glucose fluctuations have been implicated in the abnormal VSMC proliferation and complications of diabetic atherosclerosis. Docosahexaenoic acid (DHA), a ω-3 polyunsaturated fatty acid (PUFA) has been shown to inhibit proliferation of several cell types implicating several different mechanisms. In the present study, we have investigated the effects of DHA on VSMC proliferation induced by stable and intermittent high glucose levels.

Method:

Confluent cultures of rat aortic VSMCs were treated with DHA for 24 hrs and then exposed to stable high glucose (25 mmol/L, SHG) or intermittent high glucose (5 mmol/L and 25 mmol/L alternating every 12 hrs, IHG) for 72 hrs. Cell proliferation was examined by the MTT viability assay, while apoptosis process was evaluated by the Hoechst staining, flow cytometry and caspase-3 activity assays.

Results:

Our data demonstrated that the hyper proliferation induced by stable and intermittent high glucose levels was significantly inhibited by the DHA pre-treatment. DHA significantly increased caspase-3 activity, resulting in enhanced DNA fragmentation and apoptosis.

Conclusion:

Our results suggest that DHA reduced the high glucose-induced proliferation of VSMC and induced cell apoptosis.

The mTOR Signaling Pathway in Myocardial Dysfunction in Type 2 Diabetes Mellitus

PURPOSE OF REVIEW

T2DM (type 2 diabetes mellitus) is a risk factor for heart failure. The mTOR (mechanistic target of rapamycin) is a key mediator of the insulin signaling pathway. We will discuss the role of mTOR in myocardial dysfunction in T2DM.

RECENT FINDINGS

In T2DM, chronically activated mTOR induces multiple pathological events, including a negative feedback loop that suppresses IRS (insulin receptor substrate)-1. While short-term treatment with rapamycin, an mTOR inhibitor, is a promising strategy for cardiac diseases such as acute myocardial infarction and cardiac hypertrophy in T2DM, there are many concerns about chronic usage of rapamycin. Two mTOR complexes, mTORC1 and mTORC2, affect many molecules and processes via distinct signaling pathways that regulate cardiomyocyte function and survival. Understanding mechanisms underlying mTOR-mediated pathophysiological features in the heart is essential for developing effective therapies for cardiac diseases in the context of T2DM.

Cardiovascular Autonomic Neuropathy Is an Independent Risk Factor for Left Ventricular Diastolic Dysfunction in Patients with Type 2 Diabetes

Aim

This study aimed to evaluate the association between cardiovascular autonomic neuropathy (CAN) and left ventricular diastolic dysfunction (LVDD) in type 2 diabetes patients.

Methods

315 type 2 diabetes patients from inpatients of Drum Tower Hospital were included and classified into no CAN (NCAN), possible CAN (PCAN), and definite CAN (DCAN) based on cardiovascular autonomic reflex tests. The left ventricular diastolic function was assessed by tissue Doppler imaging echocardiography.

Results

The distribution of NCAN, PCAN, and DCAN was 11.4%, 51.1%, and 37.5%, respectively. The proportion of LVDD increased among the groups of NCAN, PCAN, and DCAN (39.4%, 45.3%, and 68.0%, P = 0.001). Patients with DCAN had higher filling pressure (E/e′ ratio) (10.9 ± 2.7 versus 9.4 ± 2.8, P = 0.013) and impaired diastolic performance (e′) (6.8 ± 1.7 versus 8.6 ± 2.4, P = 0.004) compared with NCAN. CAN was found to be an independent risk factor for LVDD from the multivariate regression analysis (OR = 1.628, P = 0.009, 95% CI 1.131–2.344).

Conclusions

Our results indicated that CAN was an independent risk marker for the presence of LVDD in patients with diabetes. Early diagnosis and treatment of CAN are advocated for preventing LVDD in type 2 diabetes.

Association of Impaired Glucose Regulation and Insulin Resistance With Cardiac Structure and Function: Results From ECHO-SOL (Echocardiographic Study of Latinos)

BACKGROUND

We examined the relationship between glucose homeostasis and comprehensive measures of cardiac structure and function among a representative sample of US Hispanics.

METHODS AND RESULTS

ECHO-SOL (Echocardiographic Study of Latinos), an echocardiographic ancillary study of the HCHS/SOL (Hispanic Community Health Study/Study of Latinos), enrolled 1818 Hispanic/Latino men (43%) and women (57%) aged ≥45 years (mean=56). Glucose intolerance was defined as follows: (1) prediabetes: hemoglobin (HbA1c) ≥5.7 and <6.5% and (2) diabetes mellitus: fasting plasma glucose ≥126 mg/dL, 2-hour postload glucose ≥200 mg/dL, HbA1c ≥6.5%, or hypoglycemic agent use. Uncontrolled diabetes mellitus was defined as HbA1c ≥7.0%. Insulin resistance was defined using the homeostatic model assessment for insulin resistance. Echocardiography examinations assessed left ventricular structure and systolic/diastolic function. Multivariable linear and logistic regression models were used. Prediabetes prevalence was 42%, and diabetes mellitus prevalence was 28% (47% uncontrolled). Glucose intolerance was associated with increased left ventricular posterior wall and interventricular septal and relative wall thicknesses (all P<0.05), reduced ejection fraction (P<0.01), reduced stroke and end-diastolic volumes (both P<0.001), decreased peak E' velocity (lateral and septal P<0.001), and increased E/E' ratio (lateral and septal P<0.01). The odds ratios (95% confidence intervals) for diastolic dysfunction among individuals with prediabetes and diabetes mellitus (versus diabetes mellitus free) were 1.36 (0.96-1.9) and 1.90 (1.3-2.8), respectively(P=0.006). Results were consistent for uncontrolled diabetes mellitus versus diabetes mellitus. Homeostatic model assessment for insulin resistance was associated with increased E/E' (P<0.001), and greater relative wall thickness and septal thickness (both P<0.05); lower stroke volume (P<0.0001); and lower peak lateral and septal E' velocities (both P<0.01).

CONCLUSIONS

Glucose intolerance and insulin resistance are associated with unfavorable cardiac structure and function, particularly worsened measures of diastolic function, even before the development of diabetes mellitus.

High-fat diet induces protein kinase A and G-protein receptor kinase phosphorylation of β2 -adrenergic receptor and impairs cardiac adrenergic reserve in animal hearts

Key points

Patients with diabetes show a blunted cardiac inotropic response to β‐adrenergic stimulation despite normal cardiac contractile reserve.

Acute insulin stimulation impairs β‐adrenergically induced contractile function in isolated cardiomyocytes and Langendorff‐perfused hearts.

In this study, we aimed to examine the potential effects of hyperinsulinaemia associated with high‐fat diet (HFD) feeding on the cardiac β₂‐adrenergic receptor signalling and the impacts on cardiac contractile function.

We showed that 8 weeks of HFD feeding leads to reductions in cardiac functional reserve in response to β‐adrenergic stimulation without significant alteration of cardiac structure and function, which is associated with significant changes in β₂‐adrenergic receptor phosphorylation at protein kinase A and G‐protein receptor kinase sites in the myocardium.

The results suggest that clinical intervention might be applied to subjects in early diabetes without cardiac symptoms to prevent further cardiac complications.

Abstract

Patients with diabetes display reduced exercise capability and impaired cardiac contractile reserve in response to adrenergic stimulation. We have recently uncovered an insulin receptor and adrenergic receptor signal network in the heart. The aim of this study was to understand the impacts of high‐fat diet (HFD) on the insulin–adrenergic receptor signal network in hearts. After 8 weeks of HFD feeding, mice exhibited diabetes, with elevated insulin and glucose concentrations associated with body weight gain. Mice fed an HFD had normal cardiac structure and function. However, the HFD‐fed mice displayed a significant elevation of phosphorylation of the β₂‐adrenergic receptor (β₂AR) at both the protein kinase A site serine 261/262 and the G‐protein‐coupled receptor kinase site serine 355/356 and impaired adrenergic reserve when compared with mice fed on normal chow. Isolated myocytes from HFD‐fed mice also displayed a reduced contractile response to adrenergic stimulation when compared with those of control mice fed normal chow. Genetic deletion of the β₂AR led to a normalized adrenergic response and preserved cardiac contractile reserve in HFD‐fed mice. Together, these data indicate that HFD promotes phosphorylation of the β₂AR, contributing to impairment of cardiac contractile reserve before cardiac structural and functional remodelling, suggesting that early intervention in the insulin–adrenergic signalling network might be effective in prevention of cardiac complications in diabetes.

Patients with diabetes show a blunted cardiac inotropic response to β‐adrenergic stimulation despite normal cardiac contractile reserve.

Acute insulin stimulation impairs β‐adrenergically induced contractile function in isolated cardiomyocytes and Langendorff‐perfused hearts.

In this study, we aimed to examine the potential effects of hyperinsulinaemia associated with high‐fat diet (HFD) feeding on the cardiac β₂‐adrenergic receptor signalling and the impacts on cardiac contractile function.

We showed that 8 weeks of HFD feeding leads to reductions in cardiac functional reserve in response to β‐adrenergic stimulation without significant alteration of cardiac structure and function, which is associated with significant changes in β₂‐adrenergic receptor phosphorylation at protein kinase A and G‐protein receptor kinase sites in the myocardium.

The results suggest that clinical intervention might be applied to subjects in early diabetes without cardiac symptoms to prevent further cardiac complications.

Empagliflozin: Role in Treatment Options for Patients with Type 2 Diabetes Mellitus

Empagliflozin is an oral treatment for type 2 diabetes mellitus (T2DM), one of the leading causes of death in the US and around the world. Recently, the EMPA-REG OUTCOME study has shown that empagliflozin added to standard of care treatment reduced the risk of cardiovascular (CV) events in patients with T2DM who were also at increased CV risk. The risk of major adverse CV events (MACE: first occurrence of CV death, non-fatal myocardial infarction, or non-fatal stroke) was reduced by 14% relative to placebo (HR 0.86; 95.02% CI: 0.74-0.99; P = 0.04 for superiority). The risk of CV death was reduced by 38% relative to the placebo group (HR 0.62; 95% CI: 0.49-0.77; P < 0.001) and the risk of death from any cause by 32% (HR 0.68; 95% CI: 0.57-0.82; P < 0.001). Furthermore, empagliflozin was associated with reduced risk of hospitalization for heart failure and of renal adverse events. As well as EMPA-REG OUTCOME, empagliflozin has been studied in a number of clinical trials in patients with T2DM, in various combinations, including with insulin. Empagliflozin has shown significant improvements in glycemic control, body weight, and blood pressure, albeit improvements are limited in patients with declining renal function (estimated glomerular filtration rate <45 ml/min/1.73 m2). Empagliflozin has been generally well tolerated, with the typical adverse events of genital mycotic infections usually being straightforward to manage. Considering all the data together, empagliflozin appears to be a promising option for many patients with T2DM, but care will still be needed to ensure that use is appropriate for an individual patient's characteristics.

β-Adrenergic Receptor and Insulin Resistance in the Heart

Insulin resistance is characterized by the reduced ability of insulin to stimulate tissue uptake and disposal of glucose including cardiac muscle. These conditions accelerate the progression of heart failure and increase cardiovascular morbidity and mortality in patients with cardiovascular diseases. It is noteworthy that some conditions of insulin resistance are characterized by up-regulation of the sympathetic nervous system, resulting in enhanced stimulation of β-adrenergic receptor (βAR). Overstimulation of βARs leads to the development of heart failure and is associated with the pathogenesis of insulin resistance in the heart. However, pathological consequences of the cross-talk between the βAR and the insulin sensitivity and the mechanism by which βAR overstimulation promotes insulin resistance remain unclear. This review article examines the hypothesis that βARs overstimulation leads to induction of insulin resistance in the heart.

Sex Differences in the Effect of Type 2 Diabetes on Major Cardiovascular Diseases: Results from a Population-Based Study in Italy

The aim of the study is to assess sex difference in association between type 2 diabetes and incidence of major cardiovascular events, that is, myocardial infarction, stroke, and heart failure, using information retrieved by diabetes register. The inhabitants of Reggio Emilia (Italy) aged 30-84 were followed during 2012-2014. Incidence rate ratios and 95% confidence intervals were calculated using multivariate Poisson model. The age- and sex-specific event rates were graphed. Subjects with type 2 diabetes had an excess risk compared to their counterparts without diabetes for all the three major cardiovascular events. The excess risk is similar in women and men for stroke (1.8 times) and heart failure (2.7 times), while for myocardial infarction, the excess risk in women is greater than the one observed in men (IRR 2.58, 95% CI 2.22-3.00 and IRR 1.78, 95% CI 1.60-2.00, resp.; P of interaction < 0.0001). Women had always a lesser risk than men, but in case of myocardial infarction, the women with type 2 diabetes lost part of advantage gained by women free of diabetes (IRR 0.61, 95% CI 0.53-0.72 and IRR 0.36, 95% CI 0.33-0.39, resp.). In women with type 2 diabetes, the risk of major cardiovascular events is anticipated by 20-30 years, while in men it is by 15-20.

Resveratrol Ameliorates Diabetes-Induced Cardiac Dysfunction Through AT1R-ERK/p38 MAPK Signaling Pathway

The present study was to determine the preventive effect of resveratrol (Res) on diabetes-induced cardiac dysfunction and the possible signaling pathway involved. Diabetes was induced in rats by injection of streptozotocin (STZ) at 45 mg/kg. The animals were randomly divided into three groups (10 rats/group): normal group, diabetes groups with or without Res (80 mg/kg) treatment. Biochemistry, cardiac function and fibrosis were detected. Moreover, pro-inflammatory cytokines were evaluated, and heart tissues were homogenized for western blot analysis to analyze the possible mechanisms. The results indicated that Res might regulate glucose and lipid metabolism, ameliorate cardiac function and fibrosis response in STZ-induced diabetic rats. The protective effects were consistent with the inhibition of inflammatory factors such as TNF-α, IL-6 and IL-1β. In addition, Res favorably shifted STZ-induced AT1R, ERK1/2 and p38 MAPK activation in rat heart. In conclusion, the results suggested that Res attenuated diabetes-induced cardiac dysfunction, and the effects were associated with attenuation inflammatory response and down-regulation of AT1R-ERK/p38 MAPK signaling pathway.

Inhibiting Insulin-Mediated β2-Adrenergic Receptor Activation Prevents Diabetes-Associated Cardiac Dysfunction

BACKGROUND

Type 2 diabetes mellitus (DM) and obesity independently increase the risk of heart failure by incompletely understood mechanisms. We propose that hyperinsulinemia might promote adverse consequences in the hearts of subjects with type-2 DM and obesity.

METHODS

High-fat diet feeding was used to induce obesity and DM in wild-type mice or mice lacking β₂-adrenergic receptor (β₂AR) or β-arrestin2. Wild-type mice fed with high-fat diet were treated with a β-blocker carvedilol or a GRK2 (G-protein-coupled receptor kinase 2) inhibitor. We examined signaling and cardiac contractile function.

RESULTS

High-fat diet feeding selectively increases the expression of phosphodiesterase 4D (PDE4D) in mouse hearts, in concert with reduced protein kinase A phosphorylation of phospholamban, which contributes to systolic and diastolic dysfunction. The expression of PDE4D is also elevated in human hearts with DM. The induction of PDE4D expression is mediated by an insulin receptor, insulin receptor substrate, and GRK2 and β-arrestin2-dependent transactivation of a β₂AR-extracellular regulated protein kinase signaling cascade. Thus, pharmacological inhibition of β₂AR or GRK2, or genetic deletion of β₂AR or β-arrestin2, all significantly attenuate insulin-induced phosphorylation of extracellular regulated protein kinase and PDE4D induction to prevent DM-related contractile dysfunction.

CONCLUSIONS

These studies elucidate a novel mechanism by which hyperinsulinemia contributes to heart failure by increasing PDE4D expression and identify β₂AR or GRK2 as plausible therapeutic targets for preventing or treating heart failure in subjects with type 2 DM.

Prohibitin overexpression improves myocardial function in diabetic cardiomyopathy

Prohibitin (PHB) is a highly conserved protein implicated in various cellular functions including proliferation, apoptosis, tumor suppression, transcription, and mitochondrial protein folding. However, its function in diabetic cardiomyopathy (DCM) is still unclear. In vivo, type 2 diabetic rat model was induced by using a high-fat diet and low-dose streptozotocin. Overexpression of the PHB protein in the model rats was achieved by injecting lentivirus carrying PHB cDNA via the jugular vein. Characteristics of type 2 DCM were evaluated by metabolic tests, echocardiography and histopathology. Rats with DCM showed severe insulin resistance, left ventricular dysfunction, fibrosis and apoptosis. PHB overexpression ameliorated the disease. Cardiofibroblasts (CFs) and H9c2 cardiomyoblasts were used in vitro to investigate the mechanism of PHB in altered function. In CFs treated with HG, PHB overexpression decreased expression of collagen, matrix metalloproteinase activity, and proliferation. In H9c2 cardiomyoblasts, PHB overexpression inhibited apoptosis induced by HG. Furthermore, the increased phosphorylation of extracellular signal–regulated kinase (ERK) 1/2 was significantly decreased and the inhibited phosphorylation of Akt was restored in DCM. Therefore, PHB may be a new therapeutic target for human DCM.

Electrophysiological basis of metabolic-syndrome-induced cardiac dysfunction

Myocardial contractility is controlled by intracellular Ca2+ cycling with the contribution of sarcoplasmic reticulum (SR). In this study, we aimed to investigate the role of altered SR function in defective regulation of intracellular Ca2+ levels in rats with metabolic syndrome (MetS) induced by a 16-week high-sucrose drinking-water diet. Electric-field stimulated transient intracellular Ca2+ changes in MetS cardiomyocytes exhibited significantly reduced amplitude (∼30%) and prolonged time courses (2-fold), as well as depressed SR Ca2+ loading (∼55%) with increased basal Ca2+ level. Consistent with these data, altered ryanodine receptor (RyR2) function and SERCA2a activity were found in MetS cardiomyocytes through Ca2+ spark measurements and caffeine application assay in a state in which sodium calcium exchanger was inhibited. Furthermore, tetracaine application assay results and hyperphosphorylated level of RyR2 also support the “leaky RyR2” hypothesis. Moreover, altered phosphorylation levels of phospholamban (PLN) support the depressed SERCA2a-activity thesis and these alterations in the phosphorylation of Ca2+-handling proteins are correlated with altered protein kinase and phosphatase activity in MetS cardiomyocytes. In conclusion, MetS-rat heart exhibits altered Ca2+ signaling largely due to altered SR function via changes in RyR2 and SERCA2a activity. These results point to RyR2 and SERCA2a as potential pharmacological targets for restoring intracellular Ca2+ homeostasis and, thereby, combatting dysfunction in MetS-rat heart.

Mitochondrial dysfunction and its impact on diabetic heart

Mitochondrial dysfunction and associated oxidative stress are strongly linked to cardiovascular, neurodegenerative, and age associated disorders. More specifically cardiovascular diseases are common in patients with diabetes and significant contributor to the high mortality rates associated with diabetes. Studies have shown that the heart failure risk is increased in diabetic patients even after adjusting for coronary artery disease and hypertension. Although the actual basis of the increased heart failure risk is multifactorial, increasing evidences suggest that imbalances in mitochondrial function and associated oxidative stress play an important role in this process. This review summarizes these abnormalities in mitochondrial function and discusses potential underlying mechanisms. This article is part of a Special Issue entitled: Oxidative Stress and Mitochondrial Quality in Diabetes/Obesity and Critical Illness Spectrum of Diseases - edited by P. Hemachandra Reddy.

Diabetes and Clinical and Subclinical CVD

Diabetes mellitus is a major cardiovascular risk factor and its prevalence has been increasing globally. This review examines the contributions of the MESA (Multi-Ethnic Study of Atherosclerosis), a diverse American cohort (6,814 adults ages 45 to 84, recruited from 2000 to 2002, 50% female, 62% nonwhite) toward understanding the relationship between diabetes and clinical and subclinical cardiovascular disease. People with diabetes have a high burden of subclinical vascular disease as measured by coronary artery calcification (CAC), carotid artery intima-media thickness, valvular calcification, and alterations in left ventricular structure. CAC substantially improves cardiovascular risk prediction. Among adults with diabetes, 63% had CAC >0; above CAC >400 Agatston units the event rate was 4% annually, whereas an absence of CAC was a marker of a very low cardiovascular disease rate (0.4% to 0.1% annually). These stark differences in rates may have implications for screening and/or targeted prevention efforts based on CAC burden. MESA has also provided insight on diabetes epidemiology.

Review: Biomarkers in clinical trials and drug development: measurement of cardiometabolic risk

Cardiometabolic risk is linked to a cluster of modifiable factors, including established risk factors such as obesity, dyslipidaemia, raised blood pressure, and 'nontraditional' risk factors closely related to central (especially intra-abdominal) adiposity. These 'nontraditional' risk factors include dysfunction of inflammation, coagulation, platelets, fibrinolysis, lipoproteins, endothelium, plaque instability, and miscellaneous biological processes. Both the established ('traditional') and emerging ('nontraditional') cardiometabolic risk factors are components of the metabolic syndrome.

In patients with known or suspected cardiometabolic diseases, biomarkers are increasingly being explored as indicators of disease presence, severity or activity, prognosis and therapeutic efficacy. Many biomarkers have been proposed for prediction of the macrovascular (and microvascular) complications of cardiometabolic diseases. This review provides background information on biomarkers, and an assessment of the possible utility of biomarkers in clinical trials and drug development programmes that include measurement of cardiometabolic risk.

Review: From Hypertension to Heart Failure — Are There Better Primary Prevention Strategies?

Although in the developed world the incidence of and mortality from coronary heart disease (CHD) and stroke have been declining over the last 15 years, heart failure is increasing in incidence, prevalence and overall mortality, despite advances in the diagnosis and management of the condition. Hypertension, alone or in combination with CHD, precedes the development of heart failure in the majority of both men and women. Whilst there have been improvements in the overall management of hypertension, as reflected in rates of diagnosis, awareness, treatment and control of blood pressure (BP), there are still many patients with hypertension who remain undiagnosed or untreated and of those who do receive treatment many fail to achieve current targets for BP control. Placebo controlled trials in hypertension, largely based on diuretic and beta-blocker-based regimens, have unequivocally demonstrated that the treatment of hypertension can significantly reduce the incidence of heart failure. Newer treatment strategies offer theoretical and proven practical advantages over established antihypertensive therapy. In particular, AT1-receptor blockers appear to provide benefits beyond BP control and are effective in the treatment of both hypertension and heart failure. Thus, the primary prevention of heart failure in hypertensive patients should be based upon strategies that provide tight and sustained BP control necessitating the use of multiple drugs. However, there is now compelling evidence to suggest that this therapy should include an antihypertensive agent that inhibits the reninangiotensin-aldosterone system (RAAS).

Can a Shift in Fuel Energetics Explain the Beneficial Cardiorenal Outcomes in the EMPA-REG OUTCOME Study? A Unifying Hypothesis

Type 2 diabetes mellitus causes excessive morbidity and premature cardiovascular (CV) mortality. Although tight glycemic control improves microvascular complications, its effects on macrovascular complications are unclear. The recent publication of the EMPA-REG OUTCOME study documenting impressive benefits with empagliflozin (a sodium-glucose cotransporter 2 [SGLT2] inhibitor) on CV and all-cause mortality and hospitalization for heart failure without any effects on classic atherothrombotic events is puzzling. More puzzling is that the curves for heart failure hospitalization, renal outcomes, and CV mortality begin to separate widely within 3 months and are maintained for >3 years. Modest improvements in glycemic, lipid, or blood pressure control unlikely contributed significantly to the beneficial cardiorenal outcomes within 3 months. Other known effects of SGLT2 inhibitors on visceral adiposity, vascular endothelium, natriuresis, and neurohormonal mechanisms are also unlikely major contributors to the CV/renal benefits. We postulate that the cardiorenal benefits of empagliflozin are due to a shift in myocardial and renal fuel metabolism away from fat and glucose oxidation, which are energy inefficient in the setting of the type 2 diabetic heart and kidney, toward an energy-efficient super fuel like ketone bodies, which improve myocardial/renal work efficiency and function. Even small beneficial changes in energetics minute to minute translate into large differences in efficiency, and improved cardiorenal outcomes over weeks to months continue to be sustained. Well-planned physiologic and imaging studies need to be done to characterize fuel energetics-based mechanisms for the CV/renal benefits.

High Glucose Causes Human Cardiac Progenitor Cell Dysfunction by Promoting Mitochondrial Fission: Role of a GLUT1 Blocker

Cardiovascular disease is the most common cause of death in diabetic patients. Hyperglycemia is the primary characteristic of diabetes and is associated with many complications. The role of hyperglycemia in the dysfunction of human cardiac progenitor cells that can regenerate damaged cardiac tissue has been investigated, but the exact mechanism underlying this association is not clear. Thus, we examined whether hyperglycemia could regulate mitochondrial dynamics and lead to cardiac progenitor cell dysfunction, and whether blocking glucose uptake could rescue this dysfunction. High glucose in cardiac progenitor cells results in reduced cell viability and decreased expression of cell cycle-related molecules, including CDK2 and cyclin E. A tube formation assay revealed that hyperglycemia led to a significant decrease in the tube-forming ability of cardiac progenitor cells. Fluorescent labeling of cardiac progenitor cell mitochondria revealed that hyperglycemia alters mitochondrial dynamics and increases expression of fission-related proteins, including Fis1 and Drp1. Moreover, we showed that specific blockage of GLUT1 improved cell viability, tube formation, and regulation of mitochondrial dynamics in cardiac progenitor cells. To our knowledge, this study is the first to demonstrate that high glucose leads to cardiac progenitor cell dysfunction through an increase in mitochondrial fission, and that a GLUT1 blocker can rescue cardiac progenitor cell dysfunction and downregulation of mitochondrial fission. Combined therapy with cardiac progenitor cells and a GLUT1 blocker may provide a novel strategy for cardiac progenitor cell therapy in cardiovascular disease patients with diabetes.

Effects of Dipeptidyl Peptidase 4 Inhibitors and Sodium-Glucose Linked coTransporter-2 Inhibitors on cardiovascular events in patients with type 2 diabetes mellitus: A meta-analysis

BACKGROUND

Dipeptidyl Peptidase 4 Inhibitors (DPP4-I) and Sodium-Glucose Linked coTransporter-2 Inhibitors (SGLT2-I) improve glycemic control in patients with type 2 diabetes mellitus (DM). However, only few studies were designed to assess the efficacy and safety of these drugs on cardiovascular (CV) events and mortality. The purpose of the current study was to evaluate the effects of DPP4-Is and SGLT2-Is on CV events and mortality by meta-analysis.

METHODS

Randomized trials enrolling more than 200 patients, comparing DPP-4-Is or SGLT2-Is versus placebo or active treatments in patients with DM, and reporting at least one event among all-cause and CV mortality, stroke, myocardial infarction (MI) and new onset of heart failure (HF), were included.

RESULTS

157 randomized trials (114 on DPP4-Is and 43 on SGLT2-Is) enrolling 140,470 patients (107,100 in DPP4-I and 33,370 in SGLT2-I studies) were included in the analysis. Compared to control, treatment with DPP4-Is did not affect all-cause (RR: 1.010; 95% CI: 0.935-1.091) and CV (RR: 0.975; CI: 0.887-1.073) mortality as well as risk of MI (RR: 0.915; CI: 0.835-1.002), stroke (RR: 0.933; CI: 0.820-1.062) and HF (RR: 1.083; CI: 0.973-1.205). Treatment with SGLT2-Is significantly reduced the risk of all-cause death by 28% (RR: 0.718; CI: 0.613-0.840), CV death by 33% (RR: 0.668; CI: 0.544-0.821), MI by 20% (RR: 0.803; CI: 0.668-0.965) and HF by 35% (RR: 0.652; CI: 0.517-0.823) without effect on stroke (RR: 1.158; CI: 0.912-1.469).

CONCLUSIONS

DPP4-Is show a safe CV profile as they do not affect mortality and CV events, including HF, in patients with type 2 DM. SGLT2-Is are associated with improved CV outcome and survival in DM patients.

Clinical Update: Cardiovascular Disease in Diabetes Mellitus: Atherosclerotic Cardiovascular Disease and Heart Failure in Type 2 Diabetes Mellitus - Mechanisms, Management, and Clinical Considerations

Cardiovascular disease remains the principal cause of death and disability among patients with diabetes mellitus. Diabetes mellitus exacerbates mechanisms underlying atherosclerosis and heart failure. Unfortunately, these mechanisms are not adequately modulated by therapeutic strategies focusing solely on optimal glycemic control with currently available drugs or approaches. In the setting of multifactorial risk reduction with statins and other lipid-lowering agents, antihypertensive therapies, and antihyperglycemic treatment strategies, cardiovascular complication rates are falling, yet remain higher for patients with diabetes mellitus than for those without. This review considers the mechanisms, history, controversies, new pharmacological agents, and recent evidence for current guidelines for cardiovascular management in the patient with diabetes mellitus to support evidence-based care in the patient with diabetes mellitus and heart disease outside of the acute care setting.

Risk of new-onset heart failure in patients using sitagliptin: a population-based cohort study

AIMS

To examine whether patients using sitagliptin at the time of an acute coronary syndrome event are at increased risk of incident heart failure compared with those not exposed.

METHODS

Using US claims data, people with diabetes without a history of heart failure in the 3 years before hospitalization for acute coronary syndrome were identified for the period 2004 to 2010. We used a nested case-control design, whereby cases were patients who developed incident heart failure <30 days after admission to hospital for acute coronary syndrome and were matched by age and sex with up to 10 controls with no heart failure. Subjects exposed or not exposed to sitagliptin in the 90 days before acute coronary syndrome admission were compared using conditional logistic regression after adjustment for clinical and laboratory data, healthcare utilization and propensity scores.

RESULTS

In total, 457 cases of heart failure developing de novo after diagnosis of acute coronary syndrome were matched to 4570 controls. The average age of the subjects was 55 years and 65% were male. Overall, 11 of 147 (7%) people exposed to sitagliptin developed heart failure compared with 446 of the 4880 people not exposed (9%, adjusted odds ratio 0.75, 95% CI 0.38-1.46; P=0.40). Sitagliptin exposure before acute coronary syndrome was not associated with an increased risk of death or heart failure combined (7% vs 9%, adjusted odds ratio 0.66, 95% CI 0.34-1.28).

CONCLUSIONS

In our sample of patients who are at high risk of heart failure after acute coronary syndrome, sitagliptin exposure was not associated with an increased risk of de novo heart failure.

Shengmai San Ameliorates Myocardial Dysfunction and Fibrosis in Diabetic db/db Mice

In this study, we mainly investigated the effects of Shengmai San (SMS) on diabetic cardiomyopathy (DCM) in db/db mice. The db/db mice were randomly divided into model group and SMS group, while C57BLKS/J inbred mice were used as controls. After 24-week treatment, blood glucose, body weight, and heart weight were determined. Hemodynamic changes in the left ventricle were measured using catheterization. The myocardial structure and subcellular structural changes were observed by HE staining and electron microscopy; the myocardium collagen content was quantified by Masson staining. To further explore the protective mechanism of SMS, we analyzed the expression profiles of fibrotic related proteins. Compared to nondiabetic mice, db/db mice exhibited enhanced diastolic myocardial dysfunction and adverse structural remodeling. Higher expression of profibrotic proteins and lower levels of extracellular matrix degradation were also observed. After SMS oral administration for 24 weeks, cardiac dysfunction, hypertrophy, and fibrosis in diabetic mice were greatly improved. Moreover, increased profibrotic protein expression was strongly reversed by SMS treatment in db/db mice. The results demonstrate that SMS exerts a cardioprotective effect against DCM by attenuating myocardial hypertrophy and fibrosis via a TGF-β dependent pathway.

Forkhead box transcription factor 1: role in the pathogenesis of diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is a disorder of the heart muscle in people with diabetes that can occur independent of hypertension or vascular disease. The underlying mechanism of DCM is incompletely understood. Some transcription factors have been suggested to regulate the gene program intricate in the pathogenesis of diabetes prompted cardiac injury. Forkhead box transcription factor 1 is a pleiotropic transcription factor that plays a pivotal role in a variety of physiological processes. Altered FOXO1 expression and function have been associated with cardiovascular diseases, and the important role of FOXO1 in DCM has begun to attract attention. In this review, we focus on the FOXO1 pathway and its role in various processes that have been related to DCM, such as metabolism, oxidative stress, endothelial dysfunction, inflammation and apoptosis.

The impact of an inverse correlation between plasma B-type natriuretic peptide levels and insulin resistance on the diabetic condition in patients with heart failure

BACKGROUND

A diabetic state is causally related to heart failure (HF); therefore, there should be a close correlation between the severity of diabetes and HF. However, a direct relationship between these conditions has rarely been reported and remains unclear. This study was designed to precisely examine this relationship, taking into consideration the possible association between natriuretic peptide (NP) levels and insulin resistance.

MATERIAL AND METHODS

We examined various hemodynamic parameters and simultaneously performed blood biochemical analyses of consecutive patients who underwent cardiac catheterization at our institution (n=840).

RESULTS

Simple regression analyses showed that hemoglobin A1c (HbA1c) levels were not significantly changed by the left ventricular end-diastolic pressure (LVEDP) and left ventricular ejection fraction (LVEF), which were correlated with a low cardiac index. Rather, there was a negative correlation between the HbA1c levels and plasma BNP levels as a marker of HF. A multivariate analysis showed no correlations between the HbA1c levels and cardiac functional parameters (LVEDP, LVEF or the plasma BNP levels), suggesting that the trend toward high HbA1c levels in HF cases is likely to be limited for unknown reasons. To search for an explanation of this finding, we examined the potential biological interactions between BNP and insulin resistance. A multivariate analysis revealed that the plasma BNP levels were positively correlated with age, creatinine levels and LVEDP and inversely correlated with the male gender, body mass index and HOMA-IR (homeostasis model assessment-insulin resistance) (P<0.001, respectively), but not HbA1c levels. This analysis indicated a close correlation between plasma BNP levels and insulin effectiveness in HF.

CONCLUSIONS

HF and diabetes tend to worsen with each other; however, the appearance of an association between them was likely blunted due to the considerable effect of NP in counteracting insulin resistance, even during the metabolically harmful condition of HF.

Diabetes-associated cardiac fibrosis: Cellular effectors, molecular mechanisms and therapeutic opportunities

Both type 1 and type 2 diabetes are associated with cardiac fibrosis that may reduce myocardial compliance, contribute to the pathogenesis of heart failure, and trigger arrhythmic events. Diabetes-associated fibrosis is mediated by activated cardiac fibroblasts, but may also involve fibrogenic actions of macrophages, cardiomyocytes and vascular cells. The molecular basis responsible for cardiac fibrosis in diabetes remains poorly understood. Hyperglycemia directly activates a fibrogenic program, leading to accumulation of advanced glycation end-products (AGEs) that crosslink extracellular matrix proteins, and transduce fibrogenic signals through reactive oxygen species generation, or through activation of Receptor for AGEs (RAGE)-mediated pathways. Pro-inflammatory cytokines and chemokines may recruit fibrogenic leukocyte subsets in the cardiac interstitium. Activation of transforming growth factor-β/Smad signaling may activate fibroblasts inducing deposition of structural extracellular matrix proteins and matricellular macromolecules. Adipokines, endothelin-1 and the renin-angiotensin-aldosterone system have also been implicated in the diabetic myocardium. This manuscript reviews our current understanding of the cellular effectors and molecular pathways that mediate fibrosis in diabetes. Based on the pathophysiologic mechanism, we propose therapeutic interventions that may attenuate the diabetes-associated fibrotic response and discuss the challenges that may hamper clinical translation.

Left ventricular diastolic dysfunction in nonhuman primate model of dysmetabolism and diabetes

BACKGROUND

Diabetes is one of the major risk factors for cardiomyopathy and heart failure with reduced ejection fraction (EF) and highly associated with left ventricular (LV) dysfunction in human. This study aimed 1) to noninvasively assess cardiac function using echocardiography; 2) to test the hypothesis that like diabetic human, cardiac function may also be compromised; in spontaneously developed obese, dysmetabolic and diabetic nonhuman primates (NHPs).

METHODS

Cardiovascular functions were measured by noninvasive echocardiography in 28 control, 20 dysmetabolic/pre-diabetic and 41 diabetic cynomolgus monkeys based on fasting blood glucose and other metabolic status.

RESULTS

The LV end-systolic volume (ESV) was higher while end-diastolic volume (EDV, 12 ± 5.7 mL) and EF (63 ± 12.8 %) significantly lower in the diabetic compared to control (14 ± 7 mL and 68 ± 9.8 %) group, respectively. The E/A ratio of LV trans-mitral peak flow rate during early (E) over late (A) diastole was significantly lower in the diabetic (1.19 ± 0.45) than control (1.44 ± 0.48) group. E-wave deceleration time (E DT) was prolonged in the diabetic (89 ± 41 ms) compared to control (78 ± 26 ms) group. Left atrial (LA) maximal dimension (LADmax) was significantly greater in the diabetic (1.3 ± 0.17 cm) than control (1.1 ± 0.16 cm) group. Biochemical tests showed that total cholesterol and LDL were significant higher in the diabetic (167 ± 63 and 69 ± 37 mg/dL) than both pre-diabetic (113 ± 37 and 41 ± 23 mg/dL) and control (120 ± 28 and 41 ± 17 mg/dL) groups, respectively. Multivariable logistic regression analysis demonstrated that LV systolic (reduced EF) and diastolic (abnormal E/A ratio) dysfunctions are significantly correlated with aging and hyperglycemia. Histopathology examination of the necropsy heart revealed inflammatory infiltration, cardiomyocyte hypertrophy and fragmentation, indicating the myocardial ischemia and remodeling which is consistent with the LV dysfunction phenotype.

CONCLUSIONS

Using noninvasive echocardiography, the present study demonstrated for the first time that dysmetabolic and diabetic NHPs are associated with LV systolic (increased ESV, decreased EF, etc.) and diastolic (decreased EDV and E/A ratio, prolonged E DT, etc.) dysfunctions, accompanied by LA hypertrophic remodeling (increased LADmax), the phenotypes similarly to those found in diabetic patients. Thus, spontaneously developed dysmetabolic and diabetic NHPs is a highly translatable model to human diseases not only in the pathogenic mechanisms but also can be used for testing novel therapies for cardiometabolic disorders.

Intensity of statin therapy and new hospitalizations for heart failure in patients with type 2 diabetes

OBJECTIVE

To examine a relationship between statin intensity and heart failure (HF) incidence in diabetes.

RESEARCH DESIGN AND METHODS

We performed a retrospective cohort study of patients with type 2 diabetes (n=600; age, 66.3 years; men, 68%). Patients were categorized into three groups by baseline statin treatments-moderate-intensity, low-intensity, or no statin-and the independent association between the statin category and HF hospitalization during follow-up was examined.

RESULTS

Over the course of the median 6-year follow-up, 17.7% of the patients were hospitalized for HF. Cox regression analysis revealed a significant association between the baseline statin category and HF incidence (p=0.002), independently of age, sex, hypertension, B-type natriuretic peptide, glycated hemoglobin, estimated glomerular filtration rate, and low-density lipoprotein (LDL) cholesterol levels. The moderate-intensity statin group had a significantly lower risk for HF than the low-intensity statin group with an adjusted HR of 0.31 (95% CI 0.13 to 0.65, p=0.0014). Interestingly, among patients with prevalent coronary artery diseases (CAD) and with baseline LDL controlled to less than 100 mg/dL, the frequency of HF was still significantly lower in the moderate-intensity group than in the low-intensity group or the no statin group. The effect of baseline statin category on HF was independent of incident CAD events during follow-up.

CONCLUSIONS

In type 2 diabetes, moderate-intensity statins, in comparison to low-intensity or no statin, were associated with lower HF incidence independently of LDL levels or of CAD events.

Protective mechanisms of mitochondria and heart function in diabetes

SIGNIFICANCE

The heart depends on continuous mitochondrial ATP supply and maintained redox balance to properly develop force, particularly under increased workload. During diabetes, however, myocardial energetic-redox balance is perturbed, contributing to the systolic and diastolic dysfunction known as diabetic cardiomyopathy (DC).

CRITICAL ISSUES

How these energetic and redox alterations intertwine to influence the DC progression is still poorly understood. Excessive bioavailability of both glucose and fatty acids (FAs) play a central role, leading, among other effects, to mitochondrial dysfunction. However, where and how this nutrient excess affects mitochondrial and cytoplasmic energetic/redox crossroads remains to be defined in greater detail.

RECENT ADVANCES

We review how high glucose alters cellular redox balance and affects mitochondrial DNA. Next, we address how lipid excess, either stored in lipid droplets or utilized by mitochondria, affects performance in diabetic hearts by influencing cardiac energetic and redox assets. Finally, we examine how the reciprocal energetic/redox influence between mitochondrial and cytoplasmic compartments shapes myocardial mechanical activity during the course of DC, focusing especially on the glutathione and thioredoxin systems.

FUTURE DIRECTIONS

Protecting mitochondria from losing their ability to generate energy, and to control their own reactive oxygen species emission is essential to prevent the onset and/or to slow down DC progression. We highlight mechanisms enforced by the diabetic heart to counteract glucose/FAs surplus-induced damage, such as lipid storage, enhanced mitochondria-lipid droplet interaction, and upregulation of key antioxidant enzymes. Learning more on the nature and location of mechanisms sheltering mitochondrial functions would certainly help in further optimizing therapies for human DC.

Hospitalisation for heart failure and mortality associated with dipeptidyl peptidase 4 (DPP-4) inhibitor use in an unselected population of subjects with type 2 diabetes: a nested case-control study

OBJECTIVE

The SAVOR TIMI-53 study reported a significant increase in the risk of hospitalisation for heart failure (HF) in patients treated with a DPP-4 inhibitor (DPP-4i) in comparison with placebo. A recent case-control study in part confirmed this risk signal. Our aim was to compare the occurrence of HF in relation to DPP-4i use versus any antidiabetic treatment.

DESIGN

Population-based matched case-control study conducted using administrative data.

SETTING

The Italian Region of Piedmont (4.4 million inhabitants).

PARTICIPANTS

From a database of 282,000 patients treated with antidiabetic drugs, we identified 14,613 hospitalisations for HF, 7212 incident cases, and 1727 hospital re-admissions between 2008 and 2012; each case was matched for gender, age and antidiabetic therapy with 10 controls; cases and controls were compared for exposure to DPP-4i.

OUTCOME MEASURES

ORs and 95% CIs were calculated by fitting a conditional logistic model. All analyses were adjusted for available risk factors for HF.

RESULTS

We found no increased risk of hospitalisation for HF associated with the use of DPP-4i (OR for admission for HF 1.00 (0.94 to 1.07), incident HF1.01 (0.92 to 1.11), recurrent HF 1.02 (0.84 to 1.22)). All-cause mortality was 6% lower in DPP-4i users (p<0.001), whereas insulin users showed an excess of risk for any type of hospital admission (19%) and death (20%) (p<0.001).

CONCLUSIONS

Our findings suggest that, in an unselected population of diabetic patients, the use of DPP-4i is not associated with an increased risk of HF. The favourable impact on all-cause mortality should be viewed with caution and also other explanations investigated.

Heart failure in diabetes: effects of anti-hyperglycaemic drug therapy

Individuals with diabetes are not only at high risk of developing heart failure but are also at increased risk of dying from it. Fortunately, antiheart failure therapies such as angiotensin-converting-enzyme inhibitors, β blockers and mineralocorticoid-receptor antagonists work similarly well in individuals with diabetes as in individuals without the disease. Response to intensive glycaemic control and the various classes of antihyperglycaemic agent therapy is substantially less well understood. Insulin, for example, induces sodium retention and thiazolidinediones increase the risk of heart failure. The need for new glucose-lowering drugs to show cardiovascular safety has led to the unexpected finding of an increase in the risk of admission to hospital for heart failure in patients treated with the dipeptidylpeptidase-4 (DPP4) inhibitor, saxagliptin, compared with placebo. Here we review the relation between glycaemic control and heart failure risk, focusing on the state of knowledge for the various types of antihyperglycaemic drugs that are used at present.

Alcohol and incident heart failure among middle-aged and elderly men: cohort of Swedish men

BACKGROUND

Compared with no alcohol consumption, heavy alcohol intake is associated with a higher rate of heart failure (HF) whereas light-to-moderate intake may be associated with a lower rate. However, several prior studies did not exclude former drinkers, who may have changed alcohol consumption in response to diagnosis. This study aimed to investigate the association between alcohol intake and incident HF.

METHODS AND RESULTS

We conducted a prospective cohort study of 33 760 men aged 45 to 79 years with no HF, diabetes mellitus, or myocardial infarction at baseline participating in the Cohort of Swedish Men Study. We excluded former drinkers. At baseline, participants completed a food frequency questionnaire and reported other characteristics. HF was defined as hospitalization for or death from HF, ascertained by Swedish inpatient and cause-of-death records from January 1, 1998, through December 31, 2011. We constructed Cox proportional hazards models to estimate multivariable-adjusted incidence rate ratios. During follow-up, 2916 men were hospitalized for (n=2139) or died (n=777) of incident HF. There was a U-shaped relationship between total alcohol intake and incident HF (P=0.0004). There was a nadir at light-to-moderate alcohol intake: consuming 7 to <14 standard drinks per week was associated with a 19% lower multivariable-adjusted rate of HF compared with never drinking (incidence rate ratio, 0.81; 95% confidence interval, 0.69-0.96).

CONCLUSIONS

In this cohort of Swedish men, there was a U-shaped relationship between alcohol consumption and HF incidence, with a nadir at light-to-moderate intake. Heavy intake did not seem protective.

[Latin American consensus on hypertension in patients with diabetes type 2 and metabolic syndrome]

The present document has been prepared by a group of experts, members of cardiology, endocrinology, internal medicine, nephrology and diabetes societies of Latin American countries, to serve as a guide to physicians taking care of patients with diabetes, hypertension and comorbidities or complications of both conditions. Although the concept of metabolic syndrome is currently disputed, the higher prevalence in Latin America of that cluster of metabolic alterations has suggested that metabolic syndrome is a useful nosography entity in the context of Latin American medicine. Therefore, in the present document, particular attention is paid to this syndrome in order to alert physicians on a particular high-risk population, usually underestimated and undertreated. These recommendations result from presentations and debates by discussion panels during a 2-day conference held in Bucaramanga, in October 2012, and all the participants have approved the final conclusions. The authors acknowledge that the publication and diffusion of guidelines do not suffice to achieve the recommended changes in diagnostic or therapeutic strategies, and plan suitable interventions overcoming knowledge, attitude and behavioural barriers, preventing both physicians and patients from effectively adhering to guideline recommendations.

Adenosine signalling in diabetes mellitus--pathophysiology and therapeutic considerations

Adenosine is a key extracellular signalling molecule that regulates several aspects of tissue function by activating four G-protein-coupled receptors, A1, A2A, A2B and A1 adenosine receptors. Accumulating evidence highlights a critical role for the adenosine system in the regulation of glucose homeostasis and the pathophysiology of type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM). Although adenosine signalling is known to affect insulin secretion, new data indicate that adenosine signalling also contributes to the regulation of β-cell homeostasis and activity by controlling the proliferation and regeneration of these cells as well as the survival of β cells in inflammatory microenvironments. Furthermore, adenosine is emerging as a major regulator of insulin responsiveness by controlling insulin signalling in adipose tissue, muscle and liver; adenosine also indirectly mediates effects on inflammatory and/or immune cells in these tissues. This Review critically discusses the role of the adenosine-adenosine receptor system in regulating both the onset and progression of T1DM and T2DM, and the potential of pharmacological manipulation of the adenosinergic system as an approach to manage T1DM, T2DM and their associated complications.

Prediction of heart failure in patients with type 2 diabetes mellitus- a systematic review and meta-analysis

BACKGROUND

Heart failure (HF) is a major cause of mortality and disability in type 2 diabetes mellitus (T2DM). This study sought to improve the assessment of HF risk in patients with T2DM-a step that would be critical for effective HF screening.

METHODS

A systematic literature search was performed on electronic databases including MEDLINE and EMBASE, using MeSH terms 'heart failure', 'risk factor', 'T2DM', 'cardiac dysfunction', 'stage B heart failure', 'incident heart failure', 'risk assessment', 'risk impact', 'risk score', 'predictor', 'prediction' and related free text terms. The search was limited to human studies in full-length publications in English language journal from 1946 to 2014. Univariable and multivariable relative risk (RR) and hazard ratio (HR) were obtained from each study.

RESULTS

Twenty-one studies (n=1111,569, including 507,637 subjects with T2DM) were included in this analysis with a follow-up ranging from 1 to 12 years. Associations between incident HF and risk variables described in ≥3 studies were reported. This association was greatest for insulin use (HR 2.48; 1.24-4.99), HbA1c 7.0-8.0% (2.41; 1.62-3.59), 5 years increase in age (1.47; 1.25-1.73), fasting glucose (1.28; 1.10-1.51 per standard deviation) and HbA1c (1.18; 1.14-1.23 each 1% increase). After adjustment for confounders, there were strong associations with coronary artery disease (1.77; 1.31, 2.39), HbA1c ≥ 10% (1.66; 1.45-1.89), insulin use (1.43; 1.14-1.79), HbA1c 9.0-10.0% (1.31; 1.14-1.50), fasting glucose (1.27; 1.10-1.47 per standard deviation) and 5 years increase in age (1.26; 1.13-1.40).

CONCLUSION

Among patients with T2DM, five common clinical variables are associated with significantly increased risk of incident HF.

Chronic administration of the nitroxyl donor 1-nitrosocyclo hexyl acetate limits left ventricular diastolic dysfunction in a mouse model of diabetes mellitus in vivo

BACKGROUND

Nitroxyl (HNO), a redox congener of nitric oxide (NO·), is a novel regulator of cardiovascular function, combining concomitant positive inotropic, lusitropic, and vasodilator properties. Moreover, HNO exhibits myocardial antihypertrophic and superoxide-suppressing actions. Despite these favorable actions, the impact of chronic HNO administration has yet to be reported in the context of cardiomyopathy. Diabetic cardiomyopathy is characterized by early diastolic dysfunction and adverse left ventricular (LV) structural remodeling, with LV superoxide generation playing a major causal role. We tested the hypothesis that the HNO donor 1-nitrosocyclohexylacetate (1-NCA) limits cardiomyocyte hypertrophy and LV diastolic dysfunction in a mouse model of diabetes mellitus in vivo.

METHODS AND RESULTS

Diabetes mellitus was induced in male FVB/N mice using streptozotocin. After 4 weeks, diabetic and nondiabetic mice were allocated to 1-NCA therapy (83 mg/kg per day IP) or vehicle and followed up for a further 4 weeks. Diabetes mellitus-induced LV diastolic dysfunction was evident on echocardiography-derived E and A wave velocities, E:A ratio, deceleration, and isovolumic relaxation times; LV systolic function was preserved. Increased LV cardiomyocyte size, hypertrophic and profibrotic gene expression, and upregulation of LV superoxide were also evident. These characteristics of diabetic cardiomyopathy were largely prevented by 1-NCA treatment. Selectivity of 1-NCA as an HNO donor was demonstrated by sensitivity of acute 1-NCA to l-cysteine but not to hydroxocobalamin in the normal rat heart ex vivo.

CONCLUSIONS

Our studies provide the first evidence that HNO donors may represent a promising strategy for treatment of diabetic cardiomyopathy and implies therapeutic efficacy in settings of chronic heart failure.

Diabetes, diabetic complications, and blood pressure targets

Association of diabetes with hypertension is frequent and it well known that high blood pressure potentiates the probability of diabetic patients to develop macrovascular and microvascular complications. Strong evidence obtained in a number of large scale prospective studies indicates that adequate blood pressure control in diabetic patients is highly beneficial for prevention of cardiovascular events. Nonetheless, only a limited proportion of hypertensive-diabetic individuals included in studies on anti-hypertensive treatment has met the predefined blood pressure goal. The optimal blood pressure goal to be pursued in diabetic patients with hypertension to guarantee effective protection from cardiovascular outcomes is still under intense debate and recommendations of current guidelines on hypertension treatment are still inconsistent. We comment here on the most important studies and conclude that current evidence does not conclusively support the need to reach a blood pressure target in hypertensive patients with diabetes different from nondiabetic hypertensive individuals.

IGF-2R-Gαq signaling and cardiac hypertrophy in the low-birth-weight lamb

The cardiac insulin-like growth factor 2 receptor (IGF-2R) can induce cardiomyocyte hypertrophy in a heterotrimeric G protein receptor-coupled manner involving αq (Gαq) or αs (Gαs). We have previously shown increased left ventricular weight and cardiac IGF-2 and IGF-2R gene expression in low-birth-weight (LBW) compared with average-birth-weight (ABW) lambs. Here, we have investigated the cardiac expression of IGF-2 gene variants, the degree of histone acetylation, and the abundance of proteins in the IGF-2R downstream signaling pathway in ABW and LBW lambs. Samples from the left ventricle of ABW and LBW lambs were collected at 21 days of age. There was increased phospho-CaMKII protein with decreased HDAC 4 abundance in the LBW compared with ABW lambs. There was increased GATA 4 and decreased phospho-troponin I abundance in LBW compared with ABW lambs, which are markers of pathological cardiac hypertrophy and impaired or reduced contractility, respectively. There was increased histone acetylation of H3K9 at IGF-2R promoter and IGF-2R intron 2 differentially methylated region in the LBW lamb. In conclusion, histone acetylation of IGF-2R may lead to increased IGF-2R mRNA expression and subsequently mediate Gαq signaling early in life via CaMKII, resulting in an increased risk of left ventricular hypertrophy and cardiovascular disease in adult life.