Relationship between insulin resistance and left ventricular diastolic dysfunction in patients with impaired glucose tolerance and type 2 diabetes

Decoding the Liver-Heart Axis in Cardiometabolic Diseases

The liver and heart are closely interconnected organs, and their bidirectional interaction plays a central role in cardiometabolic disease. In this review, we summarize current evidence linking liver dysfunction-particularly metabolic dysfunction-associated steatotic liver disease, alcohol-associated liver disease, and cirrhosis-with an increased risk of heart failure and other cardiovascular diseases. We discuss how these liver conditions contribute to cardiac remodeling, systemic inflammation, and hemodynamic stress and how cardiac dysfunction in turn impairs liver perfusion and promotes hepatic injury. Particular attention is given to the molecular mediators of liver-heart communication, including hepatokines and cardiokines, as well as the emerging role of advanced research methodologies, including omics integration, proximity labeling, and organ-on-chip platforms, that are redefining our understanding of interorgan cross talk. By integrating mechanistic insights with translational tools, this review aims to support the development of multiorgan therapeutic strategies for cardiometabolic disease.

The mitochondrial dicarboxylate carrier mediates in vivo hepatic gluconeogenesis

Hepatic gluconeogenesis (GNG) is essential for maintaining euglycemia during prolonged fasting. However, GNG becomes pathologically elevated and drives chronic hyperglycemia in type 2 diabetes (T2D). Lactate/pyruvate is a major GNG substrate known to be imported into mitochondria for GNG. Yet, the subsequent mitochondrial carbon export mechanisms required to supply the extra-mitochondrial canonical GNG pathway have not been genetically delineated. Here, we evaluated the role of the mitochondrial dicarboxylate carrier (DiC) in mediating GNG from lactate/pyruvate. We generated liver-specific DiC knockout (DiC LivKO) mice. During lactate/pyruvate tolerance tests, DiC LivKO decreased plasma glucose excursion and 13C-lactate/-pyruvate flux into hepatic and plasma glucose. In a Western diet (WD) feeding model of T2D, acute DiC LivKO after induction of obesity decreased lactate/pyruvate-driven GNG, hyperglycemia, and hyperinsulinemia. Our results show that mitochondrial carbon export through the DiC mediates GNG and that the DiC contributes to impaired glucose homeostasis in a mouse model of T2D.

Enhancing Memory Using Mnemonics Acronym

Traditional Chinese medicine students find pharmacology challenging because it is complicated, yet they still need to understand facts about the mechanism of actions of drugs and how to use this knowledge in clinical settings. Mnemonics are strategies that can enhance learning and memory of course material. Mnemonics are memory techniques that aid in chunking and organising material to be learnt; as a result, they improve encoding and ease retrieval. There are variety of forms that include acronyms and acrostics (also known as first-letter mnemonics), the loci method, the pegword method, the keyword approach, auditory, visual, and kinesthetic mnemonics, and a group of semantic-based mnemonic devices such as rhymes, songs, and stories.

Ca2+ mishandling and mitochondrial dysfunction: a converging road to prediabetic and diabetic cardiomyopathy

Diabetic cardiomyopathy is defined as the myocardial dysfunction that suffers patients with diabetes mellitus (DM) in the absence of hypertension and structural heart diseases such as valvular or coronary artery dysfunctions. Since the impact of DM on cardiac function is rather silent and slow, early stages of diabetic cardiomyopathy, known as prediabetes, are poorly recognized, and, on many occasions, cardiac illness is diagnosed only after a severe degree of dysfunction was reached. Therefore, exploration and recognition of the initial pathophysiological mechanisms that lead to cardiac dysfunction in diabetic cardiomyopathy are of vital importance for an on-time diagnosis and treatment of the malady. Among the complex and intricate mechanisms involved in diabetic cardiomyopathy, Ca2+ mishandling and mitochondrial dysfunction have been described as pivotal early processes. In the present review, we will focus on these two processes and the molecular pathway that relates these two alterations to the earlier stages and the development of diabetic cardiomyopathy.

Relation of cardiac function to insulin resistance as evaluated by hyperinsulinemic-euglycemic clamp analysis in individuals with type 2 diabetes

AIMS

Whereas homeostasis model assessment of insulin resistance (HOMA-IR), an easily measured but limited index of insulin resistance, has been shown to correlate with impairment of cardiac function in individuals without diabetes, the pathological relevance of insulin resistance to the development of cardiac dysfunction in individuals with type 2 diabetes has remained unclear. Here we investigated the relation between left ventricular (LV) function as assessed by echocardiography and insulin resistance as evaluated by hyperinsulinemic-euglycemic clamp analysis, the gold standard for measurement of this parameter, in individuals with type 2 diabetes.

METHODS

This retrospective study included 34 individuals with type 2 diabetes who underwent both hyperinsulinemic-euglycemic clamp analysis and echocardiography. Both the insulin sensitivity index (ISI) as determined by glucose clamp analysis as well as HOMA-IR were determined as measures of insulin resistance. The ratio of the peak early- to late-diastolic mitral inflow velocities (E/A) and the LV ejection fraction (LVEF) were determined as measures of diastolic and systolic function, respectively.

RESULTS

The ISI was significantly correlated with both the E/A ratio and LVEF (correlation coefficients of 0.480 and 0.360, respectively), whereas HOMA-IR was not correlated with either cardiac parameter. Multivariate analysis revealed that ISI was an independent predictor for both a high log [E/A] (P = 0.031) and a high LVEF (P = 0.045).

CONCLUSIONS

Insulin resistance as evaluated by hyperinsulinemic-euglycemic clamp analysis may be causally related to LV diastolic and systolic dysfunction in individuals with type 2 diabetes.

Left ventricular myocardial performance index in prediabetic patients without coronary artery disease

Background

Prediabetes is considered a major risk factor for diabetes mellitus (DM), leading to microvascular and cardiovascular disorders. Myocardial performance index (MPI) is a non-invasive Doppler method for the determination of global ventricular activity. We have not enough knowledge about the effect of prediabetes on the left ventricular (LV) function. We aimed to assess the MPI in prediabetic patients without coronary artery disease (CAD) utilizing echocardiography tissue Doppler imaging (TDI).

Results

We conducted a randomized controlled study that included fifty prediabetic patients and fifty healthy participants as the control group. All the participants were subjected to laboratory tests and echocardiography TDI to evaluate the LV systolic and diastolic functions

We found that the isovolumic relaxation time (IVRT) and MPI values were significantly increased in the prediabetic patients compared to the control group (P < 0.001). In contrast, left ventricular ejection time (ET) was significantly longer in the control group than in prediabetic patients.

Conclusion

Prediabetes may adversely affect the LV function as assessed by MPI. Screening for prediabetes and early intervention is required for the prevention of cardiovascular morbidity and mortality.

The relationship between presystolic wave and subclinical left ventricular dysfunction assessed by myocardial performance ındex in patients with polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) patients have left ventricular dysfunction (LVD) in an earlier stage. Myocardial performance index (MPI) reflects both systolic and diastolic dysfunction. A presystolic wave (PSW) detected on late diastole has been found to be associated with LVD.

AIMS

We sought to determine whether there is an association between PSW and subclinical LVD assessed by MPI in PCOS patients.

METHODS

We prospectively enrolled 106 patients diagnosed with PCOS in this study. Patients were divided into two groups based on the presence of PSW. Both groups were compared with respect to demographic, clinical, and echocardiographic properties. Univariable and multivariable regression analyses were performed to detect predictors of subclinical LVD.

RESULTS

The study included 58 patients with PSW-positive (54.7%, mean age: 23) and 48 patients with PSW-negative (45.3%, mean age: 25). PSW-positive patients had a higher waist-to-hip ratio, fasting insulin, and HOMA-IR compared to PSW-negative patients. Higher MPI velocities and more frequent subclinical LVD were observed in PSW-positive group than in PSW-negatives (p < 0.001, p = 0.0031, respectively). PSW velocity was significantly correlated with MPI velocity (r:.404, p = 0.0016). The presence of PSW, HOMA-IR, and waist-to-hip ratio > 85 were predictors of subclinical LVD in univariate logistic regression analysis. Only the presence of PSW was an independent predictor of subclinical LVD in multivariable logistic regression analysis (OR:3.257, p = 0.028).

CONCLUSION

PSW prevalence was 54.7% in PCOS patients. PSW velocity was significantly correlated with MPI velocity. The presence of PSW was independently associated with subclinical LVD in PCOS women.

Anthropometric and Biochemical Markers as Possible Indicators of Left Ventricular Abnormal Geometric Pattern and Function Impairment in Obese Normotensive Children

Εmerging data indicate that various effects of obesity on the cardiovascular system can be evident during childhood. The aim of this study was to detect early changes in left ventricular structure and function in obese normotensive children and explore possible associations of these changes with anthropometric and biochemical parameters. Normotensive 8–11-year-old obese and normal weight children were included in the study. They all underwent anthropometric measurements, laboratory tests, and echocardiography study by conventional and tissue Doppler to assess geometric pattern and function of left ventricle. Statistically significant differences in most anthropometric and metabolic parameters were noticed between groups. Obese children showed higher left ventricular mass index (LVMI) (40.05 ± 9.44 vs. 28.31 ± 6.22), lower E/A ratio (1.76 ± 0.33 vs. 2.08 ± 0.56), and higher E/e’ (6.04 ± 1.13 vs. 5.43 ± 0.96) compared to lean peers. Waist-to-height ratio and hs-CRP correlated significantly with E/A in the obese group. Left ventricular hypertrophy was present in 47.2% of obese children and eccentric was the prominent type. Waist-to-height ratio and serum cortisol levels in plasma increased the odds of having any type of abnormal ventricular geometric pattern. Echocardiographic evaluation of left ventricle and diastolic function could be considered for obese normotensive children based on waist-to-height ratio, hs-CRP, and serum cortisol.

The Peroxisome Proliferator-Activated Receptor-Gamma Coactivator-1α-Heme Oxygenase 1 Axis, a Powerful Antioxidative Pathway with Potential to Attenuate Diabetic Cardiomyopathy

Significance: From studies of diabetic animal models, the downregulation of peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α)-heme oxygenase 1 (HO-1) axis appears to be a crucial event in the development of obesity and diabetic cardiomyopathy (DCM). In this review, we discuss the role of metabolic and biochemical stressors in the rodent and human pathophysiology of DCM. A crucial contributor for many cardiac pathologies is excessive production of reactive oxygen species (ROS) pathologies, which lead to extensive cellular damage by impairing mitochondrial function and directly oxidizing DNA, proteins, and lipid membranes. We discuss the role of ROS production and inflammatory pathways with multiple contributing and confounding factors leading to DCM. Recent Advances: The relevant biochemical pathways that are critical to a therapeutic approach to treat DCM, specifically caloric restriction and its relation to the PGC-1α-HO-1 axis in the attenuation of DCM, are elucidated. Critical Issues: The increased prevalence of diabetes mellitus type 2, a major contributor to unique cardiomyopathy characterized by cardiomyocyte hypertrophy with no effective clinical treatment. This review highlights the role of mitochondrial dysfunction in the development of DCM and potential oxidative targets to attenuate oxidative stress and attenuate DCM. Future Directions: Targeting the PGC-1α-HO-1 axis is a promising approach to ameliorate DCM through improvement in mitochondrial function and antioxidant defenses. A pharmacological inducer to activate PGC-1α and HO-1 described in this review may be a promising therapeutic approach in the clinical setting.

Association of Diastolic Dysfunction with Reduced Cardiorespiratory Fitness in Adults Living with HIV

Despite the high prevalence of diastolic dysfunction in adults living with HIV, the impact on cardiorespiratory fitness (CRF) is understudied. The objective of this cross-sectional study was to investigate the relationship between cardiac function and CRF in adults with HIV. Adults receiving antiretroviral therapy with no history of coronary artery disease (CAD) or heart failure were eligible to participate. Cardiac function was assessed by resting Doppler echocardiography. CRF was measured by oxygen utilization at peak exercise (VO₂peak). The majority of participants were African American (86%) and male (97%) with a mean [standard deviation (SD)] age of 56.6 (7.1) years and median CD4 lymphocyte count of 492 cells/mL. The mean (SD) VO₂peak was 26.1 (5.5) mL/(kg·min). Age, diabetes, hypertension, and hemoglobin were associated with VO₂peak. Overall, diastolic dysfunction was present in 38% and was associated with lower VO₂peak (p < 0.05). VO₂peak was lower among those with impaired myocardial relaxation (e' <8 cm/s) compared with normal relaxation [mean ± SE mL/(kg·min), 25.2 ± 0.6 vs. 27.7 ± 0.9, p < 0.05]. Adjusted for age and clinical factors, each unit increase in left ventricular relaxation (E/A) was associated with an average 4.4 mL/(kg·min) higher VO₂peak, representing more than one metabolic equivalent. We conclude that diastolic dysfunction is independently associated with clinically significant low CRF in adults with HIV and no history of CAD or heart failure. These results highlight the importance of recognizing diastolic dysfunction in individuals living with HIV regardless of their cardiovascular disease history.

Left ventricular myocardial performance index in prediabetic patients without coronary artery disease

INTRODUCTION

Prediabetes is a high-risk condition for diabetes mellitus type 2, which is an important public health issue. The myocardial performance index (MPI) is a noninvasive Doppler measurement of global ventricular function. We evaluated the MPI and left ventricular (LV) function in prediabetic patients who did not have coronary artery disease.

METHODS

In total, 80 prediabetics (34 females and 46 males) and an equal number of sex-matched healthy volunteers (35 females and 45 males) were enrolled prospectively. All subjects underwent laboratory analyses and echocardiographic examinations, including MPI measurements.

RESULTS

There was a moderate increase in MPI between healthy controls and prediabetics (P < .001). Prediabetes was strongly associated with MPI (r = .553, P < .001). We found that MPI was associated with prediabetes on multivariate logistic regression analysis (Odds Ratio (OR) = 1.967, 95% confidence interval [CI] = 1.574-2.459, P < .001).

CONCLUSIONS

The results of this study show that systolic functions and LV diastolic parameters were adversely affected in prediabetic patients. Prediabetes is closely associated with subclinical LV systolic and diastolic dysfunction as assessed by MPI.

Echocardiographic feature of diabetic cardiomyopathy: where are we now?

We are now entering the very exciting era of treatment and management of diabetes mellitus (DM) with the emergence of new therapeutic agents, including sodium-glucose cotransporter 2 inhibitors (SGLT2i) and dipeptidyl peptidase-4 inhibitor (DPP-4i). From a cardiology and echocardiography perspective, the existence of diabetic cardiomyopathy has been proven through over four decades of discussion. DM is highly prevalent in patients with heart failure (HF). Independent associations are found after adjusting for hypertension (HTN) and coronary artery disease (CAD). In patients with both DM and HF, the prognosis is extremely dismal. In this review, the main focus is on both diabetic cardiomyopathy per se and its typical features (including myocardial additive insult related to DM), diagnosis, and management.

The relationship between insulin sensitivity and heart rate-corrected QT interval in patients with type 2 diabetes

BACKGROUND

Reduced insulin sensitivity not only contributes to the pathogenesis of type 2 diabetes but is also linked to multiple metabolic risk factors and cardiovascular diseases (CVD). A prolonged heart rate-corrected QT interval (QTc interval) is related to ventricular arrhythmias and CVD mortality and exhibits a high prevalence among type 2 diabetes patients. The aim of the study was to investigate the relationship between insulin sensitivity and the QTc interval in patients with type 2 diabetes.

METHODS

This cross-sectional observational study recruited 2927 patients with type 2 diabetes who visited the Affiliated Haian Hospital and Second Affiliated Hospital of Nantong University. The insulin sensitivity index (Matsuda index, ISI_Matsuda) derived from 75-g OGTT and other metabolic risk factors were examined in all patients. The QTc interval was estimated using a resting 12-lead electrocardiogram, and an interval longer than 440 ms was considered abnormally prolonged.

RESULTS

The QTc interval was significantly and negatively correlated with the ISI_Matsuda (r = -0.296, p < 0.001), and when the multiple linear regression analysis was adjusted for anthropometric parameters, metabolic risk factors, and current antidiabetic treatments, the QTc interval remained significantly correlated with the ISI_Matsuda (β = -0.23, t = -12.63, p < 0.001). The proportion of patients with prolonged QTc interval significantly increased from 12.1% to 17.9%, 25.6% and 37.9% from the fourth to third, second and first quartile of the ISI_Matsuda, respectively. After adjusting for anthropometric parameters by multiple logistic regression analysis, the corresponding odd ratios (ORs) for prolonged QTc interval of the first, second and third quartiles versus the fourth quartile of ISI_Matsuda were 3.11 (95% CI 2.23-4.34), 2.09 (1.51-2.88) and 1.53 (1.09-2.14), respectively, and p for trend was <0.001.

CONCLUSIONS

Reduced insulin sensitivity is associated with an increase in the QTc interval in patients with type 2 diabetes.

Assessment of the left ventricular function in normotensive prediabetics: a tissue Doppler echocardiography study

OBJECTIVE

Several studies have shown that left ventricular (LV) dysfunction is increased in individuals with diabetes. However, there are scarce data about LV function in prediabetics. This study assessed the early changes in LV diastolic and systolic myocardial function in normotensive prediabetics using tissue Doppler echocardiography (TDE).

SUBJECTS AND METHODS

We evaluated 94 patients with prediabetes (mean age of 50.8 ± 6.9 years, 78 female) without known cardiovascular diseases and 70 healthy volunteers with similar demographic characteristics. Systolic and diastolic function of the left ventricle was evaluated with transthoracic echocardiography according to the latest consensus recommendations including TDE.

RESULTS

The mean results of septal and lateral parts of the mitral annulus Pulsed wave TDE showed that myocardial systolic wave (Sm), myocardial early diastolic wave (Em) and Em to atrial peak velocity (Am) ratio were significantly lower whereas early diastolic peak flow velocity (E) to Em ratio, myocardial isovolumetric relaxation time (IVRTm), myocardial isovolumetric contraction time (IVCTm) and myocardial performance index (MPI) values were significantly higher in patients with prediabetes (preDM). In addition, mean left atrium (LA) diameter measured with M-mode echocardiography was significantly higher in prediabetics than controls.

CONCLUSION

PreDM is associated with subclinical LV systolic and diastolic dysfunction as evaluated by TDE.

The Relationship between Left Ventricular Mass Index and Insulin Sensitivity, Postprandial Glycaemia, and Fasting Serum Triglyceride and Adiponectin Levels in Patients with Type 2 Diabetes

The relationship between left ventricular mass index (LVMI) and insulin sensitivity, postprandial glycaemia, fasting serum triglyceride and adiponectin was investigated in 70 patients with type 2 diabetes. Serum fasting insulin, C-peptide, high-sensitivity C-reactive protein (hs-CRP), glycated haemoglobin (HbA1c), postprandial glycaemia, lipids and fasting serum adiponectin levels were measured. Ventricular hypertrophy was assessed at rest by electrocardiography and echocardiography. Insulin sensitivity was assessed using the homeostasis model assessment index (HOMA-IR). LVMI was assessed using the Devereux formula. Study patients had lower than normal HOMA-IR, and higher than normal serum fasting insulin levels and LVMI, and tended to have reduced insulin sensitivity. Pearson's correlation coefficient showed a statistically significant correlation between fasting serum adiponectin and LVMI, fasting serum insulin, HOMA-IR, HbA1c, serum postprandial glucose and hs-CRP. There were no statistically significant correlations between LVMI and serum hs-CRP or HOMA-IR. The results indicate the importance of fasting serum adiponectin in the development of cardiovascular complications, such as increased LVMI.

Bone mineral density is associated with left ventricular diastolic function in men with type 2 diabetes

AIMS

Type 2 diabetes (T2DM) is associated with chronic heart failure and cardiomyopathy. Furthermore, low bone mineral density (BMD) predicts incident heart failure. Abnormal diastolic function reflects early changes in cardiac function and plays a key role in the development of heart failure. The purpose of this study was to investigate the association between BMD with left ventricular (LV) diastolic function in men with T2DM.

METHODS

In all, 344 men with T2DM and 331 age-matched control subjects were enrolled. BMD measurements were performed. LV diastolic function and structure were assessed by echocardiographic evaluation.

RESULTS

BMD was lower in men with T2DM than in controls. There were significant differences in the level of parameters reflecting cardiac structure and LV diastolic function between two groups. Moreover, LV diastolic function and structure parameters also showed significant differences as BMD reduced in T2DM group. BMD at femoral neck was correlated with LV diastolic function parameters in T2DM after adjusting for confounding factors. Multivariable logistic analysis revealed that osteopenia and osteoporosis were associated with diastolic dysfunction compared to the control in men with T2DM. However, no association between BMD and LV diastolic function was found in subjects without T2DM.

CONCLUSION

Osteoporosis may be an independent factor for LV diastolic dysfunction in men with T2DM. Our data suggested that early detection of abnormal BMD should warrant for early search of undetected LV diastolic dysfunction in diabetic men.

Greater body mass index is a better predictor of subclinical cardiac damage at long-term follow-up in men than is insulin sensitivity: a prospective, population-based cohort study

BACKGROUND

To examine whether lower insulin sensitivity as determined by homeostatic model assessment (HOMA-%S) was associated with increased left ventricular mass (LVM) and presence of LV diastolic dysfunction at long-term follow-up, independently of body mass index (BMI), in middle-aged, otherwise healthy males.

METHODS

Prospective population-based cohort study with a median (IQR) follow-up time of 28 (27-28) years, in which traditional cardiovascular risk factors, including HOMA-%S and BMI, were assessed at baseline, and echocardiographic determination of LVM and LV diastolic function was performed at follow-up. Associations between risk factors and echocardiographic variables were tested using multivariable linear and binary logistic regression.

RESULTS

The study population comprised 247 men with a median (IQR) age of 47 (47-48) years. Mean (SD) BMI was 25.1 +/- 3.0 kg/m(2), and median (IQR) HOMA-%S was 113.0 (68.3-284.6). Subjects with low insulin sensitivity (lowest HOMA-%S quartile (Q1)) had significantly greater BMI, fasting plasma insulin, and higher fasting blood glucose (FBG) (p <0.02 for all). BMI and HOMA-%S were significantly correlated (r = -0.383, p <0.0001). At follow-up, mean (SD) LVM and LVMI were 202 +/- 61 g and 103 +/- 31 g/m(2), respectively, whereas median (IQR) E/é was 10 (8-12). Moreover, 36 % had grade 2 or 3 diastolic dysfunction. In multivariable analyses, greater BMI, but not low insulin sensitivity was independently associated with later detection of increased LVM and diastolic dysfunction.

CONCLUSION

Greater baseline BMI, but not lower insulin sensitivity was independently associated with greater LVM and diastolic dysfunction at long-term follow-up.

Impaired fasting glucose and left ventricular diastolic dysfunction in middle-age adults: a retrospective cross-sectional analysis of 2971 subjects

BACKGROUND

Left ventricular (LV) diastolic dysfunction (LVDD) is a well-established and early echocardiographic characteristic of diabetic cardiomyopathy. However, there are limited data on the association between impaired fasting glucose (IFG) and LVDD.

OBJECTIVE

To determine whether IFG is associated with LVDD among middle age adults.

METHODS

Amongst 3781 subjects screened in an annual health survey program and referred for an echocardiogram, 2971 individuals without LV systolic dysfunction or valvular heart disease were selected. Mean age of study population was 59 ± 12 years and 75% were men. The subjects were categorized into three groups: euglycemia (N = 2025), IFG (N = 534) and diabetes mellitus (DM; N = 412). Doppler echocardiography readers were blinded to glycemic state. Subjects with impaired LV relaxation, pseudo-normal or restrictive filling patterns were defined as having LVDD.

RESULTS

LVDD was diagnosed in 574 (19 %) of subjects and it was more prevalent among patients with IFG and DM than in euglycemic individuals (27, 30 and 15%, respectively; p < 0.001). Patients with IFG and DM had lower ratios of early (E) to late (A) trans-mitral flow (0.9 ± 0.3 and 0.9 ± 0.3 vs. 1.1 ± 0.4, respectively, p < 0.001). LV hypertrophy (LVH) was also more prevalent among patients with IFG and DM (11 and 18%, respectively, vs. 9%; p < 0.001). Multivariate binary logistic regression model adjusted to age, gender, obesity, LVH, renal function, total, high and low density lipoprotein cholesterol, triglycerides, ischemic heart disease, hypertension and LV ejection fraction showed that patients with IFG were 43% more likely to have LVDD compared with euglycemic subjects (95% confidence interval 1.12-1.83, p = 0.004).

CONCLUSIONS

IFG is independently associated with a significant increase in the likelihood for the presence of LVDD in middle aged adults.

Myocardial metabolism in diabetic cardiomyopathy: potential therapeutic targets

SIGNIFICANCE

Cardiovascular complications in diabetes are particularly serious and represent the primary cause of morbidity and mortality in diabetic patients. Despite early observations of cardiac dysfunction in diabetic humans, cardiomyopathy unique to diabetes has only recently been recognized.

RECENT ADVANCES

Research has focused on understanding the pathogenic mechanisms underlying the initiation and development of diabetic cardiomyopathy. Emerging data highlight the importance of altered mitochondrial function as a major contributor to cardiac dysfunction in diabetes. Mitochondrial dysfunction occurs by several mechanisms involving altered cardiac substrate metabolism, lipotoxicity, impaired cardiac insulin and glucose homeostasis, impaired cellular and mitochondrial calcium handling, oxidative stress, and mitochondrial uncoupling.

CRITICAL ISSUES

Currently, treatment is not specifically tailored for diabetic patients with cardiac dysfunction. Given the multifactorial development and progression of diabetic cardiomyopathy, traditional treatments such as anti-diabetic agents, as well as cellular and mitochondrial fatty acid uptake inhibitors aimed at shifting the balance of cardiac metabolism from utilizing fat to glucose may not adequately target all aspects of this condition. Thus, an alternative treatment such as resveratrol, which targets multiple facets of diabetes, may represent a safe and promising supplement to currently recommended clinical therapy and lifestyle changes.

FUTURE DIRECTIONS

Elucidation of the mechanisms underlying the initiation and progression of diabetic cardiomyopathy is essential for development of effective and targeted treatment strategies. Of particular interest is the investigation of alternative therapies such as resveratrol, which can function as both preventative and mitigating agents in the management of diabetic cardiomyopathy.

Diastolic dysfunction in the diabetic continuum: association with insulin resistance, metabolic syndrome and type 2 diabetes

Background

Diabetes increases the risk of heart failure but the underlying mechanisms leading to diabetic cardiomyopathy are poorly understood. Left ventricle diastolic dysfunction (LVDD) is one of the earliest cardiac changes in these patients. We aimed to evaluate the association between LVDD with insulin resistance, metabolic syndrome (MS) and diabetes, across the diabetic continuum.

Methods

Within a population-based study (EPIPorto), a total of 1063 individuals aged ≥45 years (38% male, 61.2 ± 9.6 years) were evaluated. Diastolic function was assessed by echocardiography, using tissue Doppler analysis (E’ velocity and E/E’ ratio) according to the latest consensus guidelines. Insulin resistance was assessed using the Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) score.

Results

The HOMA-IR score correlated to E’ velocity (ρ = −0.20;p < 0.0001) and E/E’ ratio (ρ = 0.20; p < 0.0001). There was a progressive worsening in E’ velocity (p for trend < 0.001) and in E/E’ ratio across HOMA-IR quartiles (p for trend <0.001). Individuals in the highest HOMA-IR quartile were more likely to have LVDD, even after adjustment for age, sex, blood pressure and body mass index (adjusted OR: 1.82; 95% CI: 1.09-3.03). From individuals with no MS, to patients with MS and no diabetes, to patients with diabetes, there was a progressive decrease in E’ velocity (11.2 ± 3.3 vs 9.7 ± 3.1 vs 9.2 ± 2.8 cm/s; p < 0.0001), higher E/E’ (6.9 ± 2.3 vs 7.8 ± 2.7 vs 9.0 ± 3.6; p < 0.0001) and more diastolic dysfunction (adjusted OR: 1.62; 95% CI: 1.12-2.36 and 1.78; 95% CI: 1.09-2.91, respectively).

Conclusions

HOMA-IR score and metabolic syndrome were independently associated with LVDD. Changes in diastolic function are already present before the onset of diabetes, being mainly associated with the state of insulin resistance.

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-014-0168-x) contains supplementary material, which is available to authorized users.

Mandatory oral glucose tolerance tests identify more diabetics in stable patients with chronic heart failure: a prospective observational study

BACKGROUND

Many patients with chronic heart failure (CHF) are believed to have unrecognized diabetes, which is associated with a worse prognosis. This study aimed to describe glucose tolerance in a general stable CHF population and to identify determinants of glucose tolerance focusing on body composition and skeletal muscle strength.

METHODS

A prospective observational study was set up. Inclusion criteria were diagnosis of CHF, stable condition and absence of glucose-lowering medication. Patients underwent a 2 h oral glucose tolerance test (OGTT), isometric strength testing of the upper leg and dual energy x-ray absorptiometry. Health-related quality of life and physical activity level were assessed by questionnaire.

RESULTS

Data of 56 participants were analyzed. Despite near-normal fasting glucose values, 55% was classified as prediabetic, 14% as diabetic, and 20% as normal glucose tolerant. Of all newly diagnosed diabetic patients, 79% were diagnosed because of 2 h glucose values only and none because of HbA1c. Univariate mixed model analysis revealed ischaemic aetiology, daily physical activity, E/E', fat trunk/fat limbs and extension strength as possible explanatory variables for the glucose curve during the glucose tolerance test. When combined in one model, only fat trunk/fat limbs and E/E' remained significant predictors. Furthermore, fasting insulin was correlated with fat mass/height2 (r = 0.51, p < 0.0001), extension strength (r = -0.33, p < 0.01) and triglycerides (r = 0.39, p < 0.01).

CONCLUSIONS

Our data confirm that a large majority of CHF patients have impaired glucose tolerance. This glucose intolerance is related to fat distribution and left ventricular end-diastolic pressure.

Diabetic cardiomyopathy: mechanisms and new treatment strategies targeting antioxidant signaling pathways

Cardiovascular disease is the primary cause of morbidity and mortality among the diabetic population. Both experimental and clinical evidence suggest that diabetic subjects are predisposed to a distinct cardiomyopathy, independent of concomitant macro- and microvascular disorders. 'Diabetic cardiomyopathy' is characterized by early impairments in diastolic function, accompanied by the development of cardiomyocyte hypertrophy, myocardial fibrosis and cardiomyocyte apoptosis. The pathophysiology underlying diabetes-induced cardiac damage is complex and multifactorial, with elevated oxidative stress as a key contributor. We now review the current evidence of molecular disturbances present in the diabetic heart, and their role in the development of diabetes-induced impairments in myocardial function and structure. Our focus incorporates both the contribution of increased reactive oxygen species production and reduced antioxidant defenses to diabetic cardiomyopathy, together with modulation of protein signaling pathways and the emerging role of protein O-GlcNAcylation and miRNA dysregulation in the progression of diabetic heart disease. Lastly, we discuss both conventional and novel therapeutic approaches for the treatment of left ventricular dysfunction in diabetic patients, from inhibition of the renin-angiotensin-aldosterone-system, through recent evidence favoring supplementation of endogenous antioxidants for the treatment of diabetic cardiomyopathy. Novel therapeutic strategies, such as gene therapy targeting the phosphoinositide 3-kinase PI3K(p110α) signaling pathway, and miRNA dysregulation, are also reviewed. Targeting redox stress and protective protein signaling pathways may represent a future strategy for combating the ever-increasing incidence of heart failure in the diabetic population.

Chemotherapy for testicular cancer induces acute alterations in diastolic heart function

BACKGROUND

After treatment with cisplatin-based chemotherapy for testicular cancer (TC), patients have higher prevalence of cardiovascular complications after long-term follow up. Little is known about acute cardiovascular effects of cisplatin-based chemotherapy. The aim of this study was to explore acute effects of chemotherapy on cardiac function in patients treated for TC.

METHODS

Fourteen TC patients (age 34.6 ± 12.3 years) were studied before and 3 months after start with cisplatin-based chemotherapy. Cardiac function was assessed with magnetic resonance imaging. Fasting glucose and insulin levels were measured and insulin sensitivity, reflected by the quantitative insulin sensitivity index (Quicki index), was calculated.

RESULTS

Left ventricular (LV) end-diastolic volume and LV stroke volume (SV) significantly decreased from 192 ± 27 to 175 ± 26 ml (P<0.05) and 109 ± 18 to 95 ± 16 ml (P<0.05), respectively. The ratio of early and atrial filling velocities across the mitral valve, a parameter of diastolic heart function, decreased after chemotherapy from 1.87 ± 0.43 to 1.64 ± 0.45 (P<0.01). Metabolic parameters were unfavourably changed, reflected by a decreased Quicki index, which reduced from 0.39 ± 0.05 to 0.36 ± 0.05 (P<0.05).

CONCLUSION

Chemotherapy for TC induces acute alterations in diastolic heart function, paralleled by unfavourable metabolic changes. Therefore, early after chemotherapy, metabolic treatment may be indicated to possibly reduce long-term cardiovascular complications.

Relationships among HIV infection, metabolic risk factors, and left ventricular structure and function

Our objective was to determine if the presence of metabolic complications (MC) conveyed an additional risk for left ventricular (LV) dysfunction in people with HIV. HIV⁺ and HIV⁻ men and women were categorized into four groups: (1) HIV⁺ with MC (43±7 years, n=64), (2) HIV⁺ without MC (42±7 years, n=59), (3) HIV⁻ with MC (44±8 years, n=37), or (4) HIV⁻ controls without MC (42±8 years, n=41). All participants underwent two-dimensional (2-D), Doppler, and tissue Doppler echocardiography. Overall, the prevalence of systolic dysfunction (15 vs. 4%, p=0.02) and LV hypertrophy (9 vs. 1%, p=0.03) was greater in HIV⁺ than in HIV⁻ participants. Participants with MC had a greater prevalence of LV hypertrophy (10% vs. 1%). Early mitral annular velocity during diastole was significantly (p<0.005) lower in groups with MC (HIV⁺/MC⁺: 11.6±2.3, HIV⁻/MC⁺: 12.0±2.3 vs. HIV⁺/MC⁻: 12.4±2.3, HIV⁻/MC⁻: 13.1±2.4 cm/s) and tended to be lower in groups with HIV (p=0.10). However, there was no interaction effect of HIV and MC for any systolic or diastolic variable. Regardless of HIV status, participants with MC had reduced LV diastolic function. Although both the presence of MC and HIV infection were associated with lower diastolic function, there was no additive negative effect of HIV on diastolic function beyond the effect of MC. Also, HIV was independently associated with lower systolic function. Clinical monitoring of LV function in individuals with metabolic risk factors, regardless of HIV status, is warranted.

Targeting the upregulation of reactive oxygen species subsequent to hyperglycemia prevents type 1 diabetic cardiomyopathy in mice

Cardiac oxidative stress is an early event associated with diabetic cardiomyopathy, triggered by hyperglycemia. We tested the hypothesis that targeting left-ventricular (LV) reactive oxygen species (ROS) upregulation subsequent to hyperglycemia attenuates type 1 diabetes-induced LV remodeling and dysfunction, accompanied by attenuated proinflammatory markers and cardiomyocyte apoptosis. Male 6-week-old mice received either streptozotocin (55mg/kg/day for 5 days), to induce type 1 diabetes, or citrate buffer vehicle. After 4 weeks of hyperglycemia, the mice were allocated to coenzyme Q10 supplementation (10mg/kg/day), treatment with the angiotensin-converting-enzyme inhibitor (ACE-I) ramipril (3mg/kg/day), treatment with olive oil vehicle, or no treatment for 8 weeks. Type 1 diabetes upregulated LV NADPH oxidase (Nox2, p22(phox), p47(phox) and superoxide production), LV uncoupling protein UCP3 expression, and both LV and systemic oxidative stress (LV 3-nitrotyrosine and plasma lipid peroxidation). All of these were significantly attenuated by coenzyme Q10. Coenzyme Q10 substantially limited type 1 diabetes-induced impairments in LV diastolic function (E:A ratio and deceleration time by echocardiography, LV end-diastolic pressure, and LV -dP/dt by micromanometry), LV remodeling (cardiomyocyte hypertrophy, cardiac fibrosis, apoptosis), and LV expression of proinflammatory mediators (tumor necrosis factor-α, with a similar trend for interleukin IL-1β). Coenzyme Q10's actions were independent of glycemic control, body mass, and blood pressure. Coenzyme Q10 compared favorably to improvements observed with ramipril. In summary, these data suggest that coenzyme Q10 effectively targets LV ROS upregulation to limit type 1 diabetic cardiomyopathy. Coenzyme Q10 supplementation may thus represent an effective alternative to ACE-Is for the treatment of cardiac complications in type 1 diabetic patients.

The association and predictive value analysis of metabolic syndrome on diastolic heart failure in patients at high risk for coronary artery disease

BACKGROUND

The purpose of the present study was to evaluate the effect and predictive value of metabolic syndrome (MetS) and its components on diastolic heart failure (DHF) in patients at high risk for coronary artery disease (CAD).

MATERIALS AND METHODS

We enrolled 261 patients with normal left ventricular ejection fraction (≥50%) who were scheduled to undergo coronary angiography for suspected myocardial ischemia. They were categorized into three groups (non-MetS, pre-MetS and MetS) based on the number of MetS criteria. Echocardiography was used to assess left ventricular (LV) diastolic function. The association between MetS and DHF was assessed by multivariate logistic regression (MLR) analysis (non-DHF patients as reference group) after controlling for confounders. The predictive performance of the MetS severity score (MSS) was evaluated using the area under the receiver-operating characteristic curve (AUC).

RESULTS

A tendency toward increased DHF prevalence with increasing MSS was found (p < 0.001). MLR analysis showed that in patients with an MSS of 1, the odds ratio (OR) of DHF was 1.60 (95% confidence interval-CI, 1.19-2.16; p = 0.02) compared to non-DHF patients; in patients with MSS ≥4, the OR was 6.61 (95% CI, 4.90-8.90; p < 0.001) compared to non-DHF patients. MSSs strongly predicted DHF (AUC = 0.73, 95% CI, 0.66-0.78, p < 0.001). MLR with MetS components as binary variables showed that blood pressure (BP) and triglycerides (TGs) were significantly associated with DHF (P = 0.001 and 0.043, respectively).

CONCLUSION

Our findings signify that MetS and its components of BP or TG were associated with DHF in high-risk CAD patients. DHF prevalence tends to increase with increasing MSS that has a high value in predicting DHF in high-risk CAD patients.

Early impairment of contractility reserve in patients with insulin resistance in comparison with healthy subjects

Background

Insulin resistance (IR) is currently considered a crucial cardiovascular (CV) risk factor, which seems to play a dominant role in the evolution toward cardiac and vascular impairment. Early IR-induced cardiac dysfunction can be assessed by Doppler-derived myocardial systolic strain rate (SR) index, measured at baseline and after dobutamine stress echocardiography (DSE).

Methods

Thirty IR patients (HOMA-IR = 7 ± 5.2, age 52.6 ± 2.1 years), and 20 healthy, age and sex matched controls were studied. IR had been diagnosed in all patients in the 3 months preceding the study. Dobutamine echocardiography was performed in all subjects to exclude ischemic heart disease, and left ventricular contractile reserve (LVCR) was then assessed. LVCR was evaluated as an increase in the peak of an average longitudinal SR, measured in the basal and mid segments of 2 and 4 chamber ventricular walls.

Results

No significant differences between the 2 groups were revealed by baseline echocardiography. In contrast, after DSE a significant decrease of Delta SR was found in the IR group in comparison to the controls (0.54 ± 0.31 s⁻¹vs 1.14 ± 0.45 s⁻¹; p < 0.0001).

Conclusions

Our results show that IR, even if isolated and arising within a short time period, not only represents the initial phase of future diabetes, but may adversely affect heart function, as evidenced by the depressed LVCR. Our data strengthen the need for attention to be paid to IR state and for an early therapeutic approach.

Cellular cross-talk between epicardial adipose tissue and myocardium in relation to the pathogenesis of cardiovascular disease

Epicardial and perivascular fat depot size is considered an index of cardiac and visceral obesity. The functional and anatomic proximity of epicardial adipose tissue (EAT) to myocardium has drawn increasing attention in recent years among researchers attempting to elucidate its putative role as an endocrine organ. This includes the role of EAT as a lipid storing depot and as an inflammatory tissue secreting cytokines and chemokines under pathogenic conditions such as cardiovascular diseases. In this review, we discuss the current state of knowledge regarding the potential EAT mediators of inflammation and the paracrine cross-talk between EAT and the underlying myocardium. We also highlight the most recent findings on the causes and correlates of myocardial steatosis/cardiac lipotoxicity and its association with cardiac dysfunction.

Low glial angiotensinogen improves body habitus, diastolic function, and exercise tolerance in aging male rats

OBJECTIVES

Long-term systemic blockade of the renin-angiotensin system (RAS) with either an angiotensin (Ang) II type 1 receptor antagonist or an angiotensin-converting enzyme inhibitor attenuates age-related cardiac remodeling and oxidative damage, and improves myocardial relaxation. However, the role of the brain RAS in mediating the development of diastolic dysfunction during aging is not known. We hypothesized that low brain RAS protects against the development of age-related diastolic dysfunction and left ventricular remodeling.

METHODS

Sixty-week-old transgenic male ASrAOGEN rats (n =9), with normal circulating Ang II and functionally low brain Ang II, because of a GFAP promoter-linked angiotensinogen antisense targeted to glia, and age-matched and sex-matched Hannover Sprague-Dawley (SD; n= 9) rats, with normal levels of both circulating and brain Ang II, underwent echocardiograms to evaluate cardiac structure and function. Postmortem hearts were further compared for histological, molecular, and biochemical changes consistent with cardiac aging.

RESULTS

ASrAOGEN rats showed preserved systolic and diastolic function at mid-life and this was associated with a lower, more favorable ratio of the phospholamban-SERCA2 ratio, reduced incidence of histological changes in the left ventricle, and increased cardiac Ang-(1-7) when compared with the in-vivo functional, and ex-vivo structural and biochemical indices from age-matched SD rats. Moreover, ASrAOGEN rats had lower percent body fat and a superior exercise tolerance when compared with SD rats of the same age.

CONCLUSION

Our data indicate that the central RAS plays a role in the maintenance of diastolic function and exercise tolerance in mid-life and this may be related to effects on body habitus.

Insulin resistance is not associated with myocardial steatosis in women

AIMS/HYPOTHESIS

Insulin resistance, an independent risk-factor for cardiovascular disease, precedes type 2 diabetes and is associated with ectopic lipid accumulation in skeletal muscle and liver. Recent evidence indicates that cardiac steatosis plays a central role in the development of diabetic cardiomyopathy. However, it is not known whether insulin resistance as such in the absence of type 2 diabetes is associated with heart steatosis and/or impaired function. We therefore assessed myocardial steatosis and myocardial function in a sample of women with normal insulin sensitivity, insulin resistance, impaired glucose tolerance (IGT) and type 2 diabetes.

METHODS

Magnetic resonance imaging and localised spectroscopy were used to measure left ventricular dynamic variables and myocardial lipid accumulation in interventricular septum of non-diabetic, age- and BMI-matched insulin-sensitive (n = 11, 47 ± 6 years, BMI 25 ± 2 kg/m(2); clamp-like index [CLIX] = 9.7 ± 0.7) and insulin-resistant (n = 10, 48 ± 5 years, 27 ± 4 kg/m(2); CLIX = 4.5 ± 0.4) women with normal glucose tolerance as well as of women with IGT (n = 6, 45 ± 5 years, 28 ± 6 kg/m(2); CLIX = 3.6 ± 1.1) and type 2 diabetes (n = 7, 52 ± 10 years, 27 ± 3 kg/m(2)).

RESULTS

Myocardial lipid content was increased in type 2 diabetic women only (insulin-sensitive 0.4 ± 0.2% [means ± SD]; insulin-resistant 0.4 ± 0.1%; IGT 0.5 ± 0.2%; type 2 diabetes 0.7 ± 0.3%; p < 0.05). In insulin-resistant and type 2 diabetic women, stroke volume was lower (-15% and -27%, respectively, vs insulin-sensitive) and heart rate was higher (11% and 14%, respectively, vs insulin-sensitive, p < 0.05). No other differences in systolic and diastolic function were observed between study groups.

CONCLUSIONS/INTERPRETATION

In contrast to liver and skeletal muscle, insulin resistance as such is not associated with increased myocardial lipid accumulation.

Type 2 diabetes and cardiovascular disease in South Asians

Type 2 diabetes (T2DM) is growing at a pandemic scale and is associated with a rapid increase in its complications such as cardiovascular diseases (CVD). This problem is even worse in South Asian population with South Asian people having a much higher prevalence of T2DM and CVD, occurring at an earlier age and being associated with premature and high mortality. This review looks in detail at the current knowledge on epidemiology and characteristic pathophysiology of T2DM and CVD (coronary heart disease, heart failure, stroke and peripheral vascular disease) in South Asian migrant population. Specific attention is also drawn to the role of novel risk factors and cultural and socioeconomic factors on occurrence and outcomes of these chronic diseases in this population. Finally the review makes recommendations on various measures including need for further research to tackle this serious health challenge facing the South Asian community.

Metabolic syndrome and insulin resistance are associated with abnormal left ventricular diastolic function and structure independent of blood pressure and fasting plasma glucose level

BACKGROUND

Abnormal left ventricular (LV) structure and diastolic function are frequently detected in a variety of heart diseases, and insulin resistance has been suggested to be associated with LV diastolic dysfunction (LVDD). The aims of this study were to determine the association between LVDD or LV structure and metabolic syndrome (MetS) or insulin resistance, and whether or not the associations are independent of age, blood pressure, and plasma glucose level.

METHODS

A total of 1599 subjects (1161 men and 398 women), 25-83 years of age, who underwent medical health check-ups at two institutions, were enrolled. LV diastolic function and structure were assessed by echocardiographic evaluation, including tissue Doppler imaging (TDI).

RESULTS

The subjects with MetS had significant differences in the level of parameters reflecting cardiac structure and LV diastolic function compared to those without MetS, even after adjustment for age, gender, blood pressure, and fasting plasma glucose level (P<0.001). MetS was independently associated with an increased risk for LVDD (OR, 1.67; 95% CI, 1.18-2.37; P = 0.004). In addition, as the HOMA-IR value increased, the level of parameters reflecting cardiac structure and LVDD significantly increased and the E/A ratio significantly decreased (P<0.001). Furthermore, the LV mass, E/A ratio, and E/E' ratio were significantly different across the HOMA-IR quartiles, even after adjustment for other confounders.

CONCLUSIONS

MetS and insulin resistance are associated with abnormal LV diastolic function and structure independent of age, gender, blood pressure, and fasting plasma glucose level.

Severe obstructive sleep apnea impairs left ventricular diastolic function in non-obese men

OBJECTIVE

To evaluate whether obstructive sleep apnea (OSA) contributes directly to left ventricular (LV) diastolic dysfunction.

METHODS

Seventy-four non-obese male OSA (apnea hypopnea index (AHI)⩾5/h) patients without cardiac disease, hypertension or diabetes were enrolled. Echocardiography, pulse wave velocity (PWV) measurements and laboratory testing were performed in all patients. LV diastolic function was assessed by the transmitral flow velocity (E/A ratio), and mitral annular velocity (Ea) was derived from tissue Doppler imaging (TDI).

RESULTS

The E/A ratio and Ea in the severe OSA group (AHI⩾30/h) was significantly lower than those in the mild to moderate OSA group (5⩽AHI<30/h) (P<0.0001), whereas the S/D ratio, an indicator of pulmonary vein flow velocity, in the severe OSA group was significantly higher than that in the mild to moderate OSA group (P=0.04). AHI exhibited a statistically significant inverse correlation with the E/A ratio (r=-0.47, P=0.0001), but not with relative wall thickness (RWT), LV mass index (LVMI) or PWV. RWT, LVMI and PWV exhibited an inverse correlation with the E/A ratio. Multivariate linear regression analysis revealed that severe OSA was independently associated with the E/A ratio even after adjusting for age, insulin resistance, blood pressure, LV geometry, and PWV (β=-0.23, P=0.001).

CONCLUSIONS

These results indicate that severe OSA itself may contribute directly to LV diastolic dysfunction irrespective of LV geometry, arterial stiffness, obesity and its associated cardiovascular risk factors.

A, Ribeiro JM. Is there a link between glucose levels and heart failure? An update

It has been well documented that there is an increased prevalence of standard cardiovascular (CV) risk factors in association with diabetes and with diabetes-related abnormalities. Hyperglycemia, in particular, also plays an important role. Heart failure (HF) has become a frequent manifestation of cardiovascular disease (CVD) among individuals with diabetes mellitus. Epidemiological studies suggest that the effect of hyperglycemia on HF risk is independent of other known risk factors. Analysis of datasets from populations including individuals with dysglycemia suggests the pathogenic role of hyperglycemia on left ventricular function and on the natural history of HF. Despite substantial epidemiological evidence of the relationship between diabetes and HF, data from available interventional trials assessing the effect of a glucose-lowering strategy on CV outcomes are limited. To provide some insight into these issues, we describe in this review the recent important data to understand the natural course of CV disease in diabetic individuals and the role of hyperglycemia at different times in the progression of HF.

Modification of the effect of glycemic status on aortic distensibility by age in the multi-ethnic study of atherosclerosis

Elevated serum glucose from diabetes mellitus (DM) or impaired fasting glucose shares many mechanisms with aging that decrease aortic distensibility (AD), such as glycation of the extracellular matrix. However, few data compare the simultaneous effects of elevated serum glucose and aging on AD. To study this, we examined the relationship among fasting glucose status, age, and AD in the Multi-Ethnic Study of Atherosclerosis: a multiethnic cohort of individuals aged 45 to 84 years without clinical cardiovascular disease. In the Multi-Ethnic Study of Atherosclerosis, participants with normal fasting glucose (n=2270), impaired fasting glucose (n=870), and DM (n=412) underwent MRI assessment of proximal thoracic aortic distensibility. This sample was 46% male, 42% white, 30% black, 11% Asian, and 17% Hispanic. The relationship among glucose status, age, and AD was analyzed with general linear models by adjusting for factors influential on AD. An interaction term was used to determine whether age modified the effect of glucose status on AD. AD was lowest among those with DM. The interaction term was significant (P=0.024). Comparing participants <65 years of age, AD was different between normal fasting glucose and DM (P<0.01) and between normal fasting glucose and impaired fasting glucose (P=0.02). In those >65 years of age, the fasting glucose group was no longer a significant predictor of AD. Our data indicate that there are overall differences in AD among DM, impaired fasting glucose, and normal fasting glucose. However, age modified the effect of glucose status such that differences between the groups diminished with advancing age.

Newly detected glucose disturbance is associated with a high prevalence of diastolic dysfunction: double risk for the development of heart failure?

Diastolic dysfunction is associated with a high rate of morbidity and mortality and has a high prevalence in patients with diabetes. Aim of the study was to investigate the prevalence of diastolic dysfunction in patients with newly detected glucose metabolism disorder (GMD) submitted for coronary angiography. Oral glucose tolerance test, echocardiography, and tissue Doppler imaging were performed in patients referred to coronary angiography. Prevalence of diastolic dysfunction was 97, 88, and 74% in the known diabetes, newly detected diabetes, and new diagnosed impaired glucose tolerance group, respectively. This is higher than previously reported. Severity of diastolic dysfunction was associated with higher 2-h plasma glucose levels and with new diagnosed diabetes. Screening patients with newly detected GMD for diastolic dysfunction may identify patients with double risk for cardiovascular morbidity and mortality and this group might be a target population to avoid development heart failure.

Diabetic cardiomyopathy

Diabetes mellitus is well recognized as a potent and prevalent risk factor for accelerated atherosclerosis and ischemic heart disease. However, there is also evidence of cardiac dysfunction in diabetes in the absence of coronary atherosclerosis, termed diabetic cardiomyopathy. Changes in ventricular structure and left ventricular systolic and diastolic dysfunction have all been noted even in patients with well-controlled diabetes and without overt macrovascular complications. Insulin resistance, hyperglycemia, and increased free fatty acid metabolism promote coronary microvascular disease, sympathetic nervous system dysfunction, and ventricular remodeling, and may contribute to the altered cardiac phenotype seen in diabetes. In addition to standard therapy (angiotensin-converting enzyme inhibitors and beta-blockers), diabetic patients with left ventricular dysfunction are likely to benefit from targeted therapies to reduce insulin resistance and modulate substrate use.

Hypoadiponectinemia in type 2 diabetes mellitus in men is associated with sympathetic overactivity as evaluated by cardiac 123I-metaiodobenzylguanidine scintigraphy

Hypoadiponectinemia is associated with insulin resistance. However, there is very limited information about the relationship between plasma adiponectin and cardiac autonomic nervous function. We tested the hypothesis that hypoadiponectinemia is associated with cardiac sympathetic overactivity in patients with type 2 diabetes mellitus. Thirty-three male type 2 diabetic patients not on insulin treatment were classified into a hypoadiponectinemia group (plasma adiponectin concentration, <4.0 microg/mL; age, 58.6 +/- 8.6 years [mean +/- SD]; n = 14) and an age-matched normoadiponectinemia group (serum adiponectin concentration, >/=4.0 microg/mL; age, 58.2 +/- 8.1 years; n = 19). In each patient, baroreflex sensitivity, heart rate variability, plasma norepinephrine concentration, and cardiac (123)I-metaiodobenzylguanidine (MIBG) scintigraphic findings were assessed. Compared with the normoadiponectinemia group, the hypoadiponectinemia group had a higher body mass index (P < .01), higher plasma concentrations of glucose and insulin (P < .05 and P < .01, respectively), higher homeostasis model assessment of insulin resistance (HOMA-IR) values (P < .005), higher plasma triglyceride levels (P < .05), and lower plasma high-density lipoprotein cholesterol levels (P < .05). In the hypoadiponectinemia group, the autonomic function measurements included a lower baroreflex sensitivity (P< .05) and a lower delayed myocardial uptake of (123)I-MIBG (P < .01) with a higher washout rate (P < .05). Multiple regression analysis revealed that the plasma adiponectin level was independently associated with HOMA-IR (F = 9.916) and the percent washout rate of (123)I-MIBG (F = 5.985). Our results suggest that in middle-aged men with type 2 diabetes mellitus, hypoadiponectinemia is associated with cardiac sympathetic overactivity as determined by (123)I-MIBG scintigraphy.

Left Ventricular Diastolic Dysfunction as Assessed by Echocardiography in Metabolic Syndrome

The purpose of the present study was to elucidate the cardiac structure and function in patients who have metabolic syndrome but no history of cardiovascular disease by analyzing echocardiographic findings. Echocardiographic examination was performed to screen for cardiovascular disease in 135 patients who were in their sixties. Patients were divided into metabolic syndrome (n=65, age: 65+/-2.7 years) and non-metabolic syndrome (n=70, age: 66+/-2.5 years) groups based on the criteria for metabolic syndrome proposed by the Japanese Society of Hypertension and seven other societies in 2005. The left ventricular (LV) wall thickness and dimension were measured by M-mode echocardiography. The relative wall thickness, LV mass index, and LV ejection fraction (LVEF) were calculated. LV diastolic function was assessed by the peak velocity of early rapid filling (E velocity) and the peak velocity of atrial filling (A velocity), and the ratio of E to A (E/A) was assessed by the transmitral flow. The Tei index, which reflects both LV diastolic and systolic function, was also calculated. There were no differences in relative wall thickness, LV mass index, or LVEF between the two groups. However, both the EIA and Tei index were significantly different between the metabolic syndrome (0.66+/-0.14 and 0.36+/-0.07, respectively) and non-metabolic syndrome (0.88+/-0.25 and 0.29+/-0.09) groups (p<0.001). These results indicate that patients with metabolic syndrome can have cardiac diastolic dysfunction even if they have neither LV hypertrophy nor systolic dysfunction.