Left ventricular diastolic function in type 2 diabetes mellitus: prevalence and association with myocardial and vascular disease

Prevalence, types and factors associated with echocardiographic abnormalities among newly diagnosed diabetic patients at Mulago Hospital

BACKGROUND

The prevalence of Diabetes mellitus (DM) is on a rise in sub-Saharan Africa and will more than double by 2025. Cardiovascular disease (CVD) accounts for up to 2/3 of all deaths in the diabetic population. Of all the CVD deaths in DM, 3/4 occur in sub Saharan Africa (SSA). Non invasive identification of cardiac abnormalities, such as Left Ventricular Hypertrophy (LVH), diastolic and systolic dysfunction, is not part of diabetes complications surveillance programs in Uganda and there is limited data on this problem. This study sought to determine the prevalence, types and factors associated with echocardiographic abnormalities among newly diagnosed diabetic patients at Mulago National referral hospital in Uganda.

METHODS

In this cross sectional study conducted between June 2014 and December 2014, we recruited 202 newly diagnosed adult diabetic patients. Information on patients' socio-demographics, bio-physical profile, biochemical testing and echocardiographic findings was obtained for all the participants using a pre-tested questionnaire. An abnormal echocardiogram in this study was defined as the presence of LVH, diastolic and/or systolic dysfunction and wall motion abnormality. Bivariate and multivariate logistic regression analyses were used to investigate the association of several parameters with echocardiographic abnormalities.

RESULTS

Of the 202 patients recruited, males were 102(50.5%) and the mean age was 46±15 years. Majority of patients had type 2 DM, 156(77.2%) and type 1 DM, 41(20.3%) with mean HbA1C of 13.9±5.3%. Mean duration of diabetes was 2 months. The prevalence of an abnormal echocardiogram was 67.8 % (95% CI 60%-74%). Diastolic dysfunction, systolic dysfunction, LVH and wall motion abnormalities were present in 55.0%, 21.8%, 19.3% and 4.0% of all the participants respectively. In bivariate logistic regression analysis, the factors associated with an abnormal echocardiogram were age (OR 1.09 [95% CI 1.06-1.12], P <0.0001), type 2 DM (OR 5.8[95% CI 2.77-12.07], P<0.0001), hypertension (OR 2.64[95% CI 1.44-4.85], P=0.002), obesity (OR 3.51[955 CI 1.25-9.84], P=0.017 and increased waist circumference (OR 1.02[95% CI 1.00-1.04], P=0.024. On Multiple logistic regression analysis, age was the only factor associated with an abnormal echocardiogram (OR 1.09[95%CI 1.05-1.15], P<0.0001).

CONCLUSION

Echocardiographic abnormalities were common among newly diagnosed adults with DM. Traditional CVD risk factors were associated with an abnormal echocardiogram in this patient population. Due to a high prevalence of echocardiographic abnormalities among newly diagnosed diabetics, we recommend screening for cardiac disease especially in patients who present with traditional CVD risk factors. This will facilitate early diagnosis, management and hence better patient outcomes.

Moderate intensity exercise prevents diabetic cardiomyopathy associated contractile dysfunction through restoration of mitochondrial function and connexin 43 levels in db/db mice

AIMS

Although the cardiovascular benefits of exercise are well known, exercise induced effects and mechanisms in prevention of cardiomyopathy are less clear during obesity associated type-2 diabetes. The current study assessed the impact of moderate intensity exercise on diabetic cardiomyopathy by examining cardiac function and structure and mitochondrial function.

METHODS

Obese-diabetic (db/db), and lean control (db/+) mice, were subjected to a 5 week, 300 m run on a tread-mill for 5 days/week at the speeds of 10-11 m/min. Various physiological parameters were recorded and the heart function was evaluated with M-mode echocardiography. Contraction parameters and calcium transits were examined on isolated cardiomyocytes. At the molecular level: connexin 43 and 37 (Cx43 and 37) levels, mitochondrial biogenesis regulators: Mfn2 and Drp-1 levels, mitochondrial trans-membrane potential and cytochrome c leakage were assessed through western blotting immunohistochemistry and flow cytometry. Ability of exercise to reverse oxygen consumption rate (OCR), tissue ATP levels, and cardiac fibrosis were also determined.

RESULTS

The exercise regimen was able to prevent diabetic cardiac functional deficiencies: ejection fraction (EF) and fractional shortening (FS). Improvements in contraction velocity and contraction maximum were noted with the isolated cardiomyocytes. Restoration of interstitial and micro-vessels associated Cx43 levels and improved gap junction intercellular communication (GJIC) were observed. The decline in the Mfn2/Drp-1 ratio in the db/db mice hearts was prevented after exercise. The exercise regimen further attenuated transmembrane potential decline and cytochrome c leakage. These corrections further led to improvements in OCR and tissue ATP levels and reduction in cardiac fibrosis.

CONCLUSIONS

Moderate intensity exercise produced significant cardiovascular benefits by improving mitochondrial function through restoration of Cx43 networks and mitochondrial trans-membrane potential and prevention of excessive mitochondrial fission.

Systolic aortic pressure-time area is a useful index describing arterial wave properties in rats with diabetes

The accurate measurement of arterial wave properties in terms of arterial wave transit time (τ_w) and wave reflection factor (R_f) requires simultaneous records of aortic pressure and flow signals. However, in clinical practice, it will be helpful to describe the pulsatile ventricular afterload using less-invasive parameters if possible. We investigated the possibility of systolic aortic pressure-time area (PTAs), calculated from the measured aortic pressure alone, acting as systolic workload imposed on the rat diabetic heart. Arterial wave reflections were derived using the impulse response function of the filtered aortic input impedance spectra. The cardiovascular condition in the rats with either type 1 or type 2 diabetes was characterized by (1) an elevation in PTAs; and (2) an increase in R_f and decrease in τ_w. We found that an inverse linear correlation between PTAs and arterial τ_w reached significance (τ_w = 38.5462 − 0.0022 × PTAs; r = 0.7708, P < 0.0001). By contrast, as the PTAs increased, the reflection intensity increased: R_f = –0.5439 + 0.0002 × PTAs; r = 0.8701; P <0 .0001. All these findings suggested that as diabetes stiffened aortas, the augmented aortic PTAs might act as a useful index describing the diabetes-related deterioration in systolic ventricular workload.

Relationship between increased left atrial volume and microvascular complications in patients with type 2 diabetes

AIMS

We assessed whether left atrial volume index (LAVI) was associated with the presence of microvascular complications in patients with type 2 diabetes, and whether this association was independent of hemodynamic and non-hemodynamic factors.

METHODS

We studied 157 consecutive outpatients with type 2 diabetes with no previous history of ischemic heart disease, chronic heart failure and valvular diseases. A transthoracic echocardiography and myocardial perfusion scintigraphy were performed in all participants. Presence of microvascular complications was also recorded.

RESULTS

Overall, 51 patients had decreased estimated glomerular filtration rate and/or abnormal albuminuria, 24 had diabetic retinopathy, 22 had lower-extremity sensory neuropathy, and 67 (42.7%) patients had one or more of these microvascular complications (i.e., combined endpoint). After stratifying patients by LAVI, those with LAVI ≥32 ml/m(2) had a greater prevalence of microvascular complication, lower left ventricular (LV) ejection fraction, higher LV mass index and higher E/e' ratio than those with LAVI <32 ml/m(2). Logistic regression analyses revealed that microvascular complications (singly or in combination) were associated with increased LAVI, independently of age, sex, diabetes duration, hemoglobin A1c, hypertension, LV-ejection fraction, LV mass index and the E/e' ratio.

CONCLUSIONS

These results indicate that microvascular diabetic complications are associated with increased LAVI in well-controlled type 2 diabetic patients with preserved systolic function and free from ischemic heart disease, independently of multiple potential confounders.

Pleiotropic effects of the dipeptidylpeptidase-4 inhibitors on the cardiovascular system

Dipeptidylpeptidase-4 (DPP-4) is a ubiquitously expressed transmembrane protein that removes NH2-terminal dipeptides from various substrate hormones, chemokines, neuropeptides, and growth factors. Two known substrates of DPP-4 include the incretin hormones glucagon-like peptide-1 (GLP-1) and gastric inhibitory peptide, which are secreted by enteroendocrine cells in response to postprandial hyperglycemia and account for 60–70% of postprandial insulin secretion. DPP-4 inhibitors (DPP-4i) block degradation of GLP-1 and gastric inhibitory peptide, extend their insulinotropic effect, and improve glycemia. Since 2006, several DPP-4i have become available for treatment of type 2 diabetes mellitus. Clinical trials confirm that DPP-4i raises GLP-1 levels in plasma and improves glycemia with very low risk for hypoglycemia and other side effects. Recent studies also suggest that DPP-4i confers cardiovascular and kidney protection, beyond glycemic control, which may reduce the risk for further development of the multiple comorbidities associated with obesity/type 2 diabetes mellitus, including hypertension and cardiovascular disease (CVD) and kidney disease. The notion that DPP-4i may improve CVD outcomes by mechanisms beyond glycemic control is due to both GLP-1-dependent and GLP-1-independent effects. The CVD protective effects by DPP-4i result from multiple factors including insulin resistance, oxidative stress, dyslipidemia, adipose tissue dysfunction, dysfunctional immunity, and antiapoptotic properties of these agents in the heart and vasculature. This review focuses on cellular and molecular mechanisms mediating the CVD protective effects of DPP-4i beyond favorable effects on glycemic control.

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.

Relationship of the total atrial conduction time to subclinical atherosclerosis, inflammation and echocardiographic parameters in patients with type 2 diabetes mellitus

OBJECTIVES

The aim of our study was to evaluate the total atrial conduction time and its relationship to subclinical atherosclerosis, inflammation and echocardiographic parameters in patients with type 2 diabetes mellitus.

METHODS

A total of 132 patients with type 2 diabetes mellitus (mean age 54.5 ± 9.6 years; 57.6% male) and 80 age- and gender-matched controls were evaluated. The total atrial conduction time was measured by tissue-Doppler imaging and the carotid intima-media thickness was measured by B-mode ultrasonography.

RESULTS

The total atrial conduction time was significantly longer in the patients with type 2 diabetes mellitus than in the control group (131.7 ± 23.6 vs. 113.1 ± 21.3, p<0.001). The patients with type 2 diabetes mellitus had significantly increased carotid intima-media thicknesses, neutrophil to lymphocyte ratios and high-sensitivity C-reactive protein levels than those of the controls. The total atrial conduction time was positively correlated with the high-sensitivity C-reactive protein level, neutrophil to lymphocyte ratio, carotid intima-media thickness and left atrial volume index and negatively correlated with the early diastolic velocity (Em), Em/late diastolic velocity (Am) ratio and global peak left atrial longitudinal strain. A multiple logistic regression analysis demonstrated that the neutrophil to lymphocyte ratio, carotid intima-media thickness and global peak left atrial longitudinal strain were independent predictors of the total atrial conduction time.

CONCLUSIONS

We suggest that subclinical atherosclerosis and inflammation may represent a mechanism related to prolonged total atrial conduction time and that prolonged total atrial conduction time and impaired left atrial myocardial deformation may be represent early subclinical cardiac involvement in patients with type 2 diabetes mellitus.

Lower free testosterone level is correlated with left ventricular diastolic dysfunction in asymptomatic middle-aged men with type 2 diabetes mellitus

AIMS

Low testosterone (T) level is associated with cardiovascular risk factors. However, the relationship between T level and heart function in asymptomatic men with type 2 diabetes mellitus (T2DM) is unknown.

METHODS

A total of 325 men were recruited who had no history, symptoms, or signs of heart disease.

RESULTS

T2DM had significantly lower free T (FT) levels than those with normal glucose metabolism (NGM) (428 ± 38 pmol/l vs. 444 ± 38 pmol/l, p = 0.0002), and had an increased risk of LVDD (66.1% vs. 31.8%). There was a significant difference in FT level between subjects with and without LVDD among those with T2DM (421 ± 37 pmol/l vs. 442 ± 40 pmol/l, p = 0.0007), but not among those with NGM (439 ± 37 pmol/l vs. 447 ± 39 pmol/l, p = 0.247) or in the group overall (426 ± 38 pmol/l vs. 445 ± 38 pmol/l, p = 0.156). Lower FT level was significantly associated with LVDD [univariate odds ratio (OR) = 0.63, p = 0.032; multivariate OR = 0.71, p = 0.039]. Receiver operating characteristic curve analysis of the usefulness of FT level for predicting LVDD showed an area under the curve (AUC) of 0.85 for T2DM (p < 0.001) and 0.66 for NGM (p < 0.05). FT level had a high predictive value for LVDD in T2DM (83% for FT < 414 pmol/l), but a low predictive value in NGM (61% for FT < 423 pmol/l). Comparison of the AUCs showed that FT level was more strongly correlated with LVDD in T2DM than in NGM.

CONCLUSIONS

Lower FT level is correlated with LVDD in asymptomatic middle-aged men with T2DM.

The influence of type 2 diabetes on left atrial remodeling

The influence of type 2 diabetes mellitus on cardiac remodeling has been evaluated for decades; however, the majority of investigations were focused only on the left ventricle. The impact of diabetes on the left atrial (LA) function is less researched. LA enlargement has been shown as an independent predictor of cardiovascular morbidity and mortality in the general and diabetic population; however, LA dysfunction has been proven to be an independent predictor only in the general population. There are not much follow-up data about the influence of diabetes on LA function. New echocardiographic techniques, such as 2-dimensional speckle tracking imaging, provide more accurate, sensitive, and reliable information about LA function than traditional, volumetric methods. The aim of this review was to summarize the most recent reports about the influence of diabetes on LA function, as well as to discuss the possible mechanisms and potential clinical implications of the relationship between diabetes and LA remodeling.

Left ventricular diastolic function in type 2 diabetes mellitus and the association with coronary artery calcium score: a cardiac MRI study

OBJECTIVE

The purpose of this study was to compare cardiac MRI-derived parameters of left ventricular (LV) diastolic function between uncomplicated type 2 diabetes mellitus (DM2) and normoglycemic control subjects and to evaluate whether these parameters of LV diastolic function are related to coronary atherosclerosis.

SUBJECTS AND METHODS

We prospectively studied 41 subjects with DM2 and 21 normoglycemic control subjects (30 women and 32 men; mean age, 57.2 ± 7.1 [SD] years) with no evidence of overt cardiovascular disease. We used cardiac MRI to measure LV volumes, LV peak filling rate (PFR), and transmitral flow and CT to determine coronary artery calcium scores.

RESULTS

Absolute values of the peak filling rate (PFR) were significantly lower in DM2 patients than in control subjects (mean ± SD, 293.2 ± 51.7 vs 375.7 ± 102.8 mL/s, respectively; p < 0.001). Mitral peak E velocities (mean ± SD, 42.8 ± 10.7 vs 48.8 ± 10.4 cm/s; p = 0.040) and peak E velocity-to-peak A velocity ratios (0.88 ± 0.3 vs 1.1 ± 0.3; p = 0.002) were also lower in DM2 patients compared with control subjects. DM2 patients with coronary artery calcification showed a lower PFR normalized to stroke volume (SV) (mean ± SD, 4.4 ± 1.0 vs 5.3 ± 1.4, respectively; p = 0.038) and lower mitral peak E velocities (40.1 ± 11.3 vs 48.0 ± 7.3 cm/s; p = 0.024) than DM2 patients without coronary calcification. PFR normalized to SV was independently associated with the presence of coronary artery calcification (β = -1.5, p = 0.005).

CONCLUSION

DM2 decreases cardiovascular MRI-derived parameters of LV diastolic function. Patients with DM2 and coronary atherosclerosis show a more impaired LV diastolic function than patients without coronary atherosclerosis.

Prevalence and predictors of left ventricular diastolic dysfunction in a Hispanic patient population

Minimal data exist on attributes of diastolic dysfunction in the Hispanic population. The purpose of this study was to evaluate the prevalence and predictors of diastolic dysfunction in a Hispanic patient population. We performed a retrospective review of 166 consecutive echocardiograms in a southwestern Texas Hospital that caters to a large Hispanic patient population. We identified all echocardiograms that met criteria for diastolic dysfunction and assessed baseline demographics and comorbidities in the cohort of Hispanic patients. A multivariate analysis was performed to identify the independent predictors of diastolic dysfunction. A total of 129 out of 166 patients (77.8%) were of Hispanic origin. Out of the 129 patients, 87 (67.4%) had some degree of diastolic dysfunction in this population suggesting a high prevalence in the study cohort. In the diastolic dysfunction group, the mean age was 64.5 ± 13.9, 37% were male and 63% female, 78% had diabetes, 85% had hypertension, and 49% had some degree of renal insufficiency (stages 3-5). A logistic multivariate analysis showed that diabetes was an independent predictor of diastolic dysfunction with odds ratio of 2.69 (95% confidence interval [CI], 1.06-6.28; p = 0.038). Similarly age (per year increase) and chronic kidney disease were independent predictors of diastolic dysfunction. We demonstrated that older age, presence of diabetes, and renal dysfunction are independent predictors of diastolic dysfunction in the Hispanic patient population. Strategies geared toward reducing diabetes and preventing renal dysfunction are likely to decrease prevalence of diastolic dysfunction and heart failure in this community.

Visceral adiposity index score indicated the severity of coronary heart disease in Chinese adults

BACKGROUND

Visceral adiposity contributes to cardiometabolic risk, and visceral adiposity index (VAI) had significant correlation with visceral adiposity. We aimed to explore whether VAI was associated with cardiac structure and function and assess the impact of the cut-off points of VAI defining visceral adipose dysfunction (VAD) on the severity of coronary heart disease (CHD).

METHODS

A total of 95 patients with CHD were divided into Control (nondiabetic CHD patients) and DM group (diabetic CHD patients). Then the two groups were respectively divided into VAD absent and VAD groups. Clinical, echocardiographic and coronary artery angiographic indexes were acquired to examine in relation to VAI.

RESULTS

A significant increasing trend among the four groups of patients (Control + VAD absent, Control +VAD, DM + VAD absent and DM +VAD groups) were observed for waist circumference (WC), body mass index (BMI), systolic blood pressure (SBP), glucose, VAI and Gensini score (P<0.05 for all). The following variables were associated with VAI: total cholesterol, nonesterified fatty acid, Waist-Hip ratio and SBP. VAI was independently associated with Gensini score.

CONCLUSIONS

The extent of CHD was more severe in diabetes, and VAI as a simple indicator of visceral adipose mass was strongly associated with the severity of CHD. The cut-off points of VAI used for defining VAD were more useful in diabetic CHD patients in identifying the severity of CHD.

Combination of a peroxisome proliferator-activated receptor-gamma agonist and an angiotensin II receptor blocker attenuates myocardial fibrosis and dysfunction in type 2 diabetic rats

Aims/Introduction

We aimed to examine the effect of an angiotensin II receptor blocker (ARB), a peroxisome proliferator‐activated receptor (PPAR)‐gamma agonist, and their combination on myocardial fibrosis and function in type 2 diabetic rats.

Materials and Methods

Five male Long‐Evans Tokushima Otsuka (LETO) rats and 20 male Otsuka Long‐Evans Tokushima Fatty (OLETF) rats were used. OLETF rats were assigned to four groups (n = 5 per group) at 28 weeks‐of‐age: untreated, losartan‐treated, rosiglitazone‐treated and combination‐treated. The ARB, losartan, was administered at a dose of 5 mg/kg/day, and the PPAR‐gamma agonist, rosiglitazone, was administered at a dose of 3 mg/kg/day by oral gavage for 12 weeks. Urine and blood samples were collected, and two‐dimensional echocardiograms and strain rate imaging were obtained at 28 and 40 weeks. Cytokines were evaluated by reverse transcriptase polymerase chain reaction, and histological analysis was carried out at 40 weeks.

Results

At 40 weeks, the global radial strains of the losartan‐treated (55.7 ± 4.5%, P = 0.021) and combination‐treated groups (59.3 ± 6.7%, P = 0.001) were significantly higher compared with the untreated OLETFs (44.3 ± 10.5%). No difference was observed when compared with LETO rats. Although the rosiglitazone‐treated group showed a better metabolic profile than the untreated OLETF group, there was no difference in the global radial strain (49.8 ± 6.0 vs 44.3 ± 10.5, P = 0.402). The expression of pro‐inflammatory cytokines, and collagen type I and III were consistently attenuated in the losartan‐treated and combination‐treated OLETF groups, but not in the rosiglitazone‐treated group.

Conclusions

A combination of rosiglitazone and losartan attenuates myocardial fibrosis and dysfunction in type 2 diabetic rats.

Left ventricular dysfunction in normotensive type II diabetic patients in Port Harcourt, Nigeria

Background

Diabetes mellitus (DM) is on the increase globally. Cardiovascular complications, such as left ventricular dysfunction is a major cause of death in patients with type II DM. Prior to the development of symptomatic heart failure, subclinical left ventricular dysfunction (systolic and diastolic) may exist for some time.

Aim

The aim of the study was to determine the prevalence of left ventricular dysfunction in non-hypertensive type II DM patients.

Methods

A cross sectional study of left ventricular function in 90 normotensive type II diabetes mellitus patients using echocardiography was carried out. Healthy normotensive controls matched for age, sex, and body mass index were selected for comparison. Patients and controls who had hypertension (blood pressure of >140/90 mmHg), history of smoking, significant alcohol history, pregnancy, features of thyroid disease, or valvular heart disease were excluded. Left ventricular diastolic and systolic functions were assessed.

Results

Ninety patients, (39 males and 51 females) and 90 healthy controls (39 males and 51 females) were enrolled. Mean age of patients was 50.76 ± 9.13 years and 51.33 ± 7.84 years for controls. Mean body mass index was 26.88 ± 4.73 kg/m² in patients and 27.09 ± 4.04 kg/m² in controls. Mean ejection fraction was 62.4% ± 8.47% and 68.52% ± 7.94% in patients and controls, respectively (P < 0.001). Fourteen (15.56%) patients had ejection fraction less than 55% compared to four (4.44%) in controls (P < 0.001; odds ratio = 3.96). Impaired diastolic function was found in 65.6% of patients compared to 3.3% of controls (P < 0.001). Left ventricular mass index of >99 kg/m² in females and >115 kg/m² in males was considered abnormal. The left ventricular mass index was also higher in patients than in controls (95.17 ± 25.67 g/m² versus 85.40 ± 18.0 g/m²; P = 0.004).

Conclusion

Normotensive diabetic patients have a high prevalence of left ventricular dysfunction even in the absence of cardiac symptoms

Dipeptidylpeptidase inhibition is associated with improvement in blood pressure and diastolic function in insulin-resistant male Zucker obese rats

Diastolic dysfunction is a prognosticator for future cardiovascular events that demonstrates a strong correlation with obesity. Pharmacological inhibition of dipeptidylpeptidase-4 (DPP-4) to increase the bioavailability of glucagon-like peptide-1 is an emerging therapy for control of glycemia in type 2 diabetes patients. Accumulating evidence suggests that glucagon-like peptide-1 has insulin-independent actions in cardiovascular tissue. However, it is not known whether DPP-4 inhibition improves obesity-related diastolic dysfunction. Eight-week-old Zucker obese (ZO) and Zucker lean rats were fed normal chow diet or diet containing the DPP-4 inhibitor, linagliptin (LGT), for 8 weeks. Plasma DPP-4 activity was 3.3-fold higher in ZO compared with Zucker lean rats and was reduced by 95% with LGT treatment. LGT improved echocardiographic and pressure volume-derived indices of diastolic function that were impaired in ZO control rats, without altering food intake or body weight gain during the study period. LGT also blunted elevated blood pressure progression in ZO rats involving improved skeletal muscle arteriolar function, without reducing left ventricular hypertrophy, fibrosis, or oxidative stress in ZO hearts. Expression of phosphorylated- endothelial nitric oxide synthase (eNOS)(Ser1177), total eNOS, and sarcoplasmic reticulum calcium ATPase 2a protein was elevated in the LGT-treated ZO heart, suggesting improved Ca(2+) handling. The ZO myocardium had an abnormal mitochondrial sarcomeric arrangement and cristae structure that were normalized by LGT. These studies suggest that LGT reduces blood pressure and improves intracellular Cai(2+) mishandling and cardiomyocyte ultrastructure, which collectively result in improvements in diastolic function in the absence of reductions in left ventricular hypertrophy, fibrosis, or oxidative stress in insulin-resistant ZO rats.

Left atrial volume index is a predictor of silent myocardial ischemia in high-risk patients with end-stage renal disease

Silent myocardial ischemia is highly prevalent in patients with end-stage renal disease (ESRD), and is associated with poor cardiovascular outcomes. However, the criteria for coronary artery disease screening remain unclear in asymptomatic patients. The goal of this study was to evaluate whether baseline echocardiographic parameters can predict myocardial ischemia in asymptomatic patients with ESRD. We investigated 259 high-risk asymptomatic patients with ESRD who underwent both echocardiography and myocardial perfusion single-photon emission computed tomography at the initiation of dialysis. We defined the presence of myocardial ischemia as a reversible or fixed perfusion defect. Silent myocardial ischemia was found in 99 (38.2 %) high-risk asymptomatic patients with ESRD at the initiation of dialysis. In patients with myocardial ischemia, left ventricular (LV) end systolic volume index, LV mass index, left atrial volume index (LAVI), and the ratio of early mitral inflow velocity to peak mitral annulus velocity were significantly higher, and LV ejection fraction was significantly lower, than those without myocardial ischemia. Multivariate analysis showed that LAVI, LV ejection fraction, and regional wall motion abnormalities were independently associated with the presence of silent myocardial ischemia. Severe (LA) enlargement was independently associated with the presence of silent myocardial ischemia (odds ratio 1.97; 95 % confidence interval 1.08-3.57; p = 0.026). LA enlargement is a potential marker for identifying patients with ESRD at high risk of silent myocardial ischemia.

Diabetes and coronary heart disease: a risk factor for the global epidemic

Cardiovascular disease remains a leading cause of death in the United States and the world. In this we will paper focus on type 2 diabetes mellitus as a risk factor for coronary heart disease, review the mechanisms of atherogenesis in diabetics, the impact of hypertension and the treatment goals in diabetics, the guidelines for screening, and review the epidemiologic consequences of diabetes and heart disease on a global scale. The underlying premise to consider diabetes a cardiovascular disease equivalent will be explored as well as the recommendations for screening and cardiac testing for asymptomatic diabetic patients.

Diastolic dysfunction in asymptomatic type 2 diabetes mellitus with normal systolic function

BACKGROUND

The incidence of heart failure in diabetic subjects is high even in the absence of hypertension and coronary artery disease.

AIMS

The purpose of this study was to study the incidence of diastolic dysfunction in diabetic subjects and its relation to age, duration of diabetes mellitus (DM), Glycosylated hemoglobin (HbA1c) levels, obesity indices and diabetic microangiopathies.

SETTINGS AND DESIGN

This was a case control prospective study conducted at the teaching hospital during a one year period.

MATERIALS AND METHODS

A total of 127 subjects (case) with type 2 diabetes of more than five years duration were studied. Total 100 healthy subjects were included as the control group. Echocardiography was performed to assess left ventricular diastolic function.

RESULTS

Out of the total 127 subjects, 69 (54.33%) from the case group had diastolic dysfunction, and 11% amongst 100 in the control group population showed the diastolic dysfunction (P < 0.001). Patients with a longer duration of DM (of 11 to 15 years) had a higher prevalence of diastolic dysfunction (P < 0.02). Subjects with high waist circumference and high waist to hip ratio had statistically significant diastolic dysfunction with 'P' =0.001 and 'P' = < 0.02 respectively. Subjects with HbA1c > 7.5% had a higher prevalence of diastolic dysfunction than subjects with HbA1c < 7.5% (P < 0.02). Diastolic dysfunction was present in majority of the subjects with autonomic neuropathy and retinopathy.

CONCLUSIONS

Present study reveals high incidence of diastolic dysfunction in asymptomatic diabetic; subjects and, this finding was correlated with the duration of diabetes, HbA1c levels, obesity indices and diabetic microangiopathies. We conclude that early diagnosis and institution of treatment will reduce morbidity and improve the outcomes, and prevent future heart failure.

Do diabetes, metabolic syndrome or their association equally affect biventricular function? A tissue Doppler study

Metabolic syndrome (MetS) and type 2 diabetes (T2DM) have been associated with an impairment of left (LV) and right ventricular (RV) function as well as an increased risk of heart failure (HF). However, it remains unclear whether these clinical entities or their associations promote a similar derangement of biventricular function. Overall, 345 patients without overt cardiovascular disease consecutively underwent routine blood chemistry including high-sensitivity C reactive protein (hs-CRP) and echocardiographical examination with conventional and tissue Doppler imaging (TDI) of both ventricles. According to the ATP III criteria and fasting glucose levels, the study population was stratified into four groups: (1) healthy controls (n=120); (2) MetS without T2DM (n=84); (3) T2DM without MetS (n=49); and (4) MetS+T2DM (n=92). The Myocardial performance index (MPI) of the RV and LV was obtained with a multi-segmental approach using TDI. Patients with MetS and T2DM exhibited a similar impairment of biventricular function compared with healthy controls, whereas a further decline was observed in patients having both MetS and T2DM. In addition to MetS markers, hs-CRP exhibited the strongest association with the MPI of both ventricles. Regression analyses indicated that individual MetS markers were inferior to MetS in identifying subtle cardiac dysfunction. Independent associations of MetS and T2DM with biventricular dysfunction were comparable, and the coexistence of MetS and T2DM exhibited the highest risk for biventricular dysfunction. Our findings emphasize the importance of MetS as an equivalent of T2DM and support a synergic effect of these clinical conditions on cardiac organ damage requiring more aggressive therapeutic strategies to prevent HF.

Emerging role of epigenetics and miRNA in diabetic cardiomyopathy

The prevalence of heart failure independent of coronary artery disease and hypertension is increasing rapidly in diabetic patients. Thus, this pathophysiology has been recognized as a distinct clinical entity termed "diabetic cardiomyopathy." Several studies support the notion that diabetes is a threatening insult for the myocardium resulting in functional, cellular, and structural changes manifesting as a cardiac myopathy. Recent data suggested that epigenetics including DNA and histone modifications as well as microRNAs play an important role in the development of cardiac diseases. The role of epigenetics in diabetes is largely recognized; however, its role in diabetes-associated cardiomyopathy remains elusive. Thus, molecular, cellular, and functional modulations in the diabetic cardiomyopathy will be investigated in this review. Moreover, particular attention will be drawn on the epigenetic mechanisms that may play an important role in the pathophysiology of diabetic cardiomyopathy.

Excess protein O-GlcNAcylation and the progression of diabetic cardiomyopathy

We examined the role that enzymatic protein O-GlcNAcylation plays in the development of diabetic cardiomyopathy in a mouse model of Type 2 diabetes mellitus (DM2). Mice injected with low-dose streptozotocin and fed a high-fat diet developed mild hyperglycemia and obesity consistent with DM2. Studies were performed from 1 to 6 mo after initiating the DM2 protocol. After 1 mo, DM2 mice showed increased body weight, impaired fasting blood glucose, and hyperinsulinemia. Echocardiographic evaluation revealed left ventricular diastolic dysfunction by 2 mo and O-GlcNAcylation of several cardiac proteins and of nuclear transcription factor Sp1. By 4 mo, systolic dysfunction was observed and sarcoplasmic reticulum Ca(2+) ATPase expression decreased by 50%. Fibrosis was not observed at any timepoint in DM2 mice. Levels of the rate-limiting enzyme of the hexosamine biosynthetic pathway, glutamine:fructose-6-phosphate amidotransferase (GFAT) were increased as early as 2 mo. Fatty acids, which are elevated in DM2 mice, can possibly be linked to excessive protein O-GlcNAcylation levels, as cultured cardiac myocytes in normal glucose treated with oleic acid showed increased O-GlcNAcylation and GFAT levels. These data indicate that the early onset of diastolic dysfunction followed by the loss of systolic function, in the absence of cardiac hypertrophy or fibrosis, is associated with increased cardiac protein O-GlcNAcylation and increased O-GlcNAcylation levels of key calcium-handling proteins. A link between excessive protein O-GlcNAcylation and cardiac dysfunction is further supported by results showing that reducing O-GlcNAcylation by O-GlcNAcase overexpression improved cardiac function in the diabetic mouse. In addition, fatty acids play a role in stimulating excess O-GlcNAcylation. The nature and time course of changes observed in cardiac function suggest that protein O-GlcNAcylation plays a mechanistic role in the triggering of diabetic cardiomyopathy in DM2.

Left atrial volume index as a marker of left ventricular diastolic dysfunction in asymptomatic Tanzanian diabetic patients

AIM

To determine the prevalence of left atrial (LA) enlargement and its relation to left ventricular (LV) diastolic dysfunction among asymptomatic diabetic outpatients attending Muhimbili National Hospital in Dar es Salaam, Tanzania.

METHODS

Echocardiography was performed in 122 type 2 and 58 type 1 diabetic patients. Diastolic dysfunction was defined as peak transmitral blood velocity to medial mitral annulus velocity (E/E') ratio ≥ 15. LA volume indexed to body surface area (LAVI) was considered enlarged if ≥ 29 ml/m(2).

RESULTS

Enlarged LAVI and LV diastolic dysfunction were more common in type 2 than in type 1 diabetic patients (44.3 vs 25.9% and 20.5 vs 3.5%, respectively, both p < 0.05). In multivariate linear regression analysis, larger LAVI was associated with LV diastolic dysfunction independent of significant associations with LV mass index and presence of mitral regurgitation in type 2 diabetic patients, while LV mass index, lower ejection fraction and longer duration of diabetes were the main covariates of larger LAVI in type 1 diabetic patients (all p < 0.05).

CONCLUSION

Enlarged LA is common among asymptomatic Tanzanian diabetic patients, and particularly associated with LV diastolic dysfunction in type 2, and with cardiomyopathy and lower systolic function in type 1 diabetic patients.

Diabetic cardiomyopathy and diastolic heart failure -- difficulties with relaxation

Diabetic patients carry a four- to five-fold increased risk of heart failure. Hyperglycaemia plays a central role in the pathogenesis of diabetic cardiomyopathy. Diabetic cardiomyopathy represents a distinct structural and functional disorder of the myocardium characterized by cardiac hypertrophy and an increased myocardial stiffness. At an early stage, diabetic cardiomyopathy is manifested by diastolic heart failure with preserved ejection fraction. In some patients, diastolic dysfunction may progress to heart failure with reduced ejection fraction and result in overt systolic heart failure. Diastolic dysfunction can accurately be diagnosed by echocardiography and BNP measurement in daily clinical practice. Early treatment is prognostically important. Optimal control of blood glucose levels and blood pressure is beneficial. So far metformin is the only antidiabetic agent not associated with harm in diabetic patients with heart failure. Incretin-based therapies potentially provide cardiovascular benefits. ACE inhibitors, angiotensin-1 receptor antagonists and beta-blockers should be preferred in heart failure therapy.

Changes in left atrial volume in diabetes mellitus: more than diastolic dysfunction?

AIM

To evaluate left atrial (LA) volume and function as assessed by strain and strain rate derived from 2D speckle tracking and their association with diastolic dysfunction (DD) in patients with diabetes mellitus (DM).

METHODS AND RESULTS

Seventy three patients with DM were compared with age- and gender-matched normal controls; 30 patients with DM alone were compared to those with hypertension (HT) alone. The maximum LA volume, traditional measures of atrial function, 2D strain and strain rate were analysed. The LA indexed volume (LAVI) was larger in DM group than that in normal controls (38.2 ± 9.9 vs. 20.5 ± 4.8 ml/m(2), P< 0.0001), as well as in DM alone compared with hypertensive patients (33.9 ± 10 vs. 25.7 ± 8 ml/m(2), P< 0.0001). Global strain was significantly reduced in the DM group compared with that in normal controls (22.5 ± 8.67 vs. 30.6 ± 8.27%; P< 0.0001) but was similar with HT. There was a weak correlation between LAVI and global strain with increasing grades of DD (r= 0.439, P< 0.0001 and r= - 0.316, P< 0.0001, respectively) in the diabetic group. However, there was no significant difference in LAVI between these groups. A logistic regression analysis for predictors of LAVI demonstrated that only diabetes was a determinant of LAVI. Patients with diabetes showed a significant reduction in global strain compared with normal controls but no difference with increasing grades of diastolic function.

CONCLUSIONS

LA enlargement in DM is independent of associated HT and diastolic function. LA enlargement is associated with LA dysfunction as evaluated by 2D strain. It is likely that a combination of DD and a diabetic atrial myopathy contribute to LA enlargement in patients with DM.

Diabetic cardiomyopathy: myth or reality?

Diabetes mellitus has reached an epidemic level worldwide. Cardiovascular diseases are the primary cause of death in diabetic patients, not only because of coronary artery disease and associated hypertension but also because of a direct adverse effect of diabetes on the heart, independent of other potential aetiological factors. However, the existence of this 'diabetic cardiomyopathy' remains controversial. We aimed to review current evidence for the existence of diabetic cardiomyopathy, focusing particularly on the clinical setting.

NT-proBNP, echocardiographic abnormalities and subclinical coronary artery disease in high risk type 2 diabetic patients

Background

Intensive multifactorial treatment aimed at prevention of cardiovascular (CV) disease may reduce left ventricular (LV) echocardiographic abnormalities in diabetic subjects. Plasma N-terminal (NT)-proBNP predicts CV mortality in diabetic patients but the association between P-NT-proBNP and the putative residual abnormalities in such patients are not well described. This study examined echocardiographic measurements of LV hypertrophy, atrial dilatation and LV dysfunction and their relation to P-NT-proBNP levels or subclinical coronary artery disease (CAD) in type 2 diabetic patients with microalbuminuria receiving intensive multifactorial treatment.

Methods

Echocardiography including tissue Doppler imaging and P-NT-proBNP measurements were performed in 200 patients without prior CAD. Patients with P-NT-proBNP > 45.2 ng/L and/or coronary calcium score ≥ 400 were stratified as high risk patients for CAD(n = 133) and examined for significant CAD by myocardial perfusion imaging and/or CT-angiography and/or coronary angiography.

Results

LV mass index was 41.2 ± 10.9 g/m^2.7 and 48 (24%) patients had LV hypertrophy. LA and RA dilatation were found in 54(27%) and 45(23%) patients, respectively, and LV diastolic dysfunction was found in 109(55%) patients. Patients with increased P-NT-proBNP levels did not have more major echocardiographic abnormalities. In 70(53%) of 133 high risk patients significant CAD was demonstrated and patients with LV hypertrophy had increased risk of significant CAD(adjusted odd ratio[CI] was 4.53[1.14-18.06]).

Conclusion

Among asymptomatic type 2 diabetic patients with microalbuminuria that received intensive multifactorial treatment, P-NT-proBNP levels is not associated with echocardiographic abnormalities. LV diastolic dysfunction was frequently observed, whereas LV hypertrophy was less frequent but associated with significant CAD.

Left ventricular diastolic function in type 2 diabetes mellitus is associated with myocardial triglyceride content but not with impaired myocardial perfusion reserve

PURPOSE

To study myocardial perfusion reserve and myocellular metabolic alterations indicated by triglyceride content as possible causes of diastolic dysfunction in patients with type 2 diabetes mellitus, preserved systolic function, and without clinically evident coronary artery disease.

MATERIALS AND METHODS

Patients with type 2 diabetes mellitus (n = 42) underwent cardiac magnetic resonance (CMR) for quantification of 1) myocardial contractility by strain-encoded MR (SENC); 2) myocardial triglyceride content by proton magnetic resonance spectroscopy ((1) H-MRS); and 3) myocardial perfusion reserve during pharmacologic hyperemia. Age-matched healthy volunteers (n = 16) also underwent CMR to acquire normal values for myocardial strain and perfusion reserve.

RESULTS

Stress CMR procedures were successfully performed in all subjects, and no regional inducible perfusion defects were observed in type 2 diabetes mellitus patients. Diastolic strain rate and myocardial perfusion reserve were significantly impaired in patients with type 2 diabetes mellitus compared to control subjects (P < 0.001 for both). Interestingly, impaired diastolic function in type 2 diabetes mellitus was not associated with impaired myocardial perfusion reserve (r = 0.12, P = NS). Conversely a significant association was observed between diastolic dysfunction and myocardial triglyceride content (r = -0.71, P < 0.001), which proved to be independent of age, gender, diabetes duration, blood pressure, and fasting blood glucose.

CONCLUSION

Myocardial steatosis may represent an early marker of diabetic heart disease, triggering subclinical myocardial dysfunction irrespective of myocardial perfusion reserve.

Circulation: Cardiovascular Imaging Editors' Picks

The following articles are being highlighted as part of Circulation: Cardiovascular Imaging 's Topic Review. This series summarizes the most important articles, as selected by the editors, that have published in the Circulation portfolio. The studies included in this article represent the most significant research in the area of myocardial disease.

Diastolic dysfunction in patients with type 2 diabetes mellitus: is it really the first marker of diabetic cardiomyopathy?

BACKGROUND

Diastolic dysfunction is considered the first marker of diabetic cardiomyopathy. However, preclinical systolic alteration was also recently described by strain, but its association with diastolic dysfunction has never been investigated.

METHODS

One hundred fourteen patients with type 2 diabetes mellitus (DM) with controlled blood pressure and without overt heart disease were prospectively enrolled and compared with 88 age-matched controls. All subjects underwent comprehensive echocardiography, including diastolic evaluation according to current recommendations and speckle-tracking imaging. The prevalence of diastolic dysfunction, the determinants of diastolic parameters, and the association between preclinical systolic and diastolic dysfunctions were studied.

RESULTS

Diastolic parameters were altered in patients compared with controls, with lower E/A ratios, longer mitral deceleration and isovolumic relaxation times, and higher E/e' ratio. Diastolic dysfunction occurred in 47% of patients with DM (33% and 14% with grade I and II diastolic dysfunction, respectively) and systolic alteration (longitudinal strain ≥ -18%) in 32% of patients. Whereas longitudinal systolic strain was independently associated with DM and gender, diastolic parameters were influenced by many factors, including age, rate-pressure product, history of hypertension, and body mass index. Systolic alteration occurred in 28% of patients with DM with normal diastolic function and in 35% with diastolic dysfunction.

CONCLUSIONS

Diastolic dysfunction diagnosed according to current recommendations is frequent in patients with DM but is also influenced by other factors. Systolic strain alteration may exist despite normal diastolic function, indicating that diastolic dysfunction should not be considered the first marker of a preclinical form of diabetic cardiomyopathy.

Exercise Tolerance and the Post Exercise Diastolic Filling Pattern in Patients With the Resting Impaired Relaxation

Background

In patients with normal LV systolic function, cardiac output increases with exercise mediated by increased stroke volume early in exercise and an increase in heart rate later in exercise. Despite normal LV systolic function, patients who display an impaired relaxation pattern may have a reduced exercise tolerance. We hypothesized that the resting impaired relaxation pattern that persists during exercise results in reduced LV filling volume and reduced exercise tolerance.

Methods

We evaluated consecutive exercise echocardiograms performed at Harper Hospital from 1998-2000 for patients with sinus rhythm, normal resting wall motion and ejection fraction (> 55%), evidence of resting impaired relaxation, and a negative exercise echocardiogram. There were 49 patients fitting the above criteria who were compared with a group of age and sex matched patients (43 patients) with a normal rest and exercise echocardiogram with normal resting transmitral Doppler. Rest and post exercise echocardiography and Doppler parameters were obtained.

Results

Patients in the impaired relaxation group demonstrated shorter exercise times as compared to the normal control group (8.8 ± 1.6 versus 9.7 ± 2.0 minutes, P < 0.001). In patients with normal resting transmitral diastolic filling, there was an increased the extent of atrial contribution to LV filling volume post exercise associated with shortening of isovolumic relaxation. Two patterns were seen in the impaired relaxation group post exercise. In 1 subgroup in which E/A ratio decreased post exercise, exercise duration was reduced (7.4 ± 1.3 minutes, P < 0.001) as compared to the subgroup with E/A increase (9.6 ± 1.2 minutes) post exercise which was similar to normal controls. Forward stepwise regression indicated that exercise time was primarily related to E/A change post exercise for all patient groups (r = 0.625, P = 0.0008). Specifically, this was true for patients with E/A reversal at rest (r = 0.584, P = 0.0028). However, for patients with normal diastolic filling at rest, the diastolic velocity integral was the major predictor (r = 0.695, P < 0.0084).

Conclusion

We conclude that the transmitral Doppler pattern post exercise provides insight into the mechanism of reduced exercise tolerance in some patients with the resting impaired relaxation pattern. Preservation of this pattern post exercise is associated with reduced exercise tolerance.

Severity of erectile dysfunction could predict left ventricular diastolic dysfunction in patients without overt cardiac complaint

INTRODUCTION

It has been repeatedly demonstrated that presence of erectile dysfunction (ED) may predate the occurrence of overt event of coronary artery disease. However, the association between severity of ED and left ventricular diastolic dysfunction (LVDD) was rarely reported.

AIM

The aim of this study was to assess the association between severity of ED and LVDD in patients without overt cardiac complaint.

MAIN OUTCOME MEASURES

The International Index of Erectile Function (IIEF) was used to assess erectile function. Diastolic Doppler parameters measurements and tissue Doppler imaging were used to assess left ventricular diastolic function.

METHODS

A total of 230 male ED patients without overt cardiac complaint were enrolled in this study. Erectile function was assessed using the IIEF. Patients were also screened for socio demographic data and medical comorbidities that included age, smoking, diabetes, hypertension, and dyslipidemia. All patients were referred to cardiologist for cardiac assessment. Left ventricular diastolic function that included diastolic Doppler parameters measurements and tissue Doppler imaging were also assessed.

RESULTS

Mean age±standard deviation was 57.5±5.6 (range of 42-81). There were significant associations between the following risk factors: age, obesity, smoking, hypertension, dyslipidemia, and increased severity of ED (P<0.05 for each). Of the patients, 77.4%, 74.8%, 80%, and 66.1% had abnormal transmitral E/A (E/A) ratio, deceleration time (DT), isovolumic relaxation time (IVRT), mitral E velocity/tissue Doppler imaging E velocity (E/Em) ratio, respectively. Only the means of IVRT and (E/Em) ratio had significant associations with increased severity of ED (P<0.001 for each). There were significant associations between increased severity of ED and the following categorical echo parameters: grades 1 and 2 of E/A ratio, DT, IVRT, and grades 1, 2, and 3 of (E/Em) ratio (P<0.05 for each).

CONCLUSIONS

The current study clearly demonstrated that LVDD is prevalent among patients with ED-associated medical comorbidities without overt cardiac complaint. There were significant associations between increased severity of ED and presence of LVDD in those patients.

Competing risks of heart failure with preserved ejection fraction in diabetic patients

AIMS

The prevalence of heart failure with preserved ejection fraction (HFpEF) has increased in the past two decades, and diabetes mellitus (DM) is frequently associated with HFpEF. Although it has been demonstrated that left ventricular (LV) diastolic and vascular functional abnormalities are generally observed in HFpEF, it remains to be clinically elucidated how an asymptomatic stage progresses to symptomatic HFpEF in DM patients. We aimed to identify risk factors associated with incident HFpEF in DM patients and to evaluate the contribution of LV relaxation and compliance to the development of HFpEF.

METHODS AND RESULTS

The study included 544 consecutive Japanese DM patients with ejection fraction ≥50%. Patients with coronary artery disease or serum creatinine ≥2.0 mg/dL were excluded. Multiple logistic regression analysis revealed that obesity, female gender, anaemia, and impaired LV compliance were independently associated with the prevalence of HFpEF, and that age, LV mass index, an index of LV relaxation, estimated glomerular filtration rate, and history of hypertension were not. There was no difference in haemoglobin A1c or brachial-ankle pulse wave velocity between the DM patients with and without HFpEF.

CONCLUSIONS

This study suggests that exacerbation of LV compliance impairment, rather than of relaxation abnormality or vascular stiffening, plays a crucial role in the induction of HFpEF in DM patients regardless of the severity of DM and renal dysfunction. Anaemia and obesity may also contribute to the transition from asymptomatic stage to symptomatic HFpEF even without further progression of LV diastolic dysfunction.

Cardiovascular comorbidities of type 2 diabetes mellitus: defining the potential of glucagonlike peptide-1-based therapies

The global epidemic of diabetes mellitus (~95% type 2 diabetes) has been fueled by a parallel increase in obesity and overweight. Together, these metabolic disease epidemics have contributed to the increasing incidence and prevalence of cardiovascular disease. The accumulation of metabolic and cardiovascular risk factors in patients with type 2 diabetes--risk factors that may exacerbate one another--complicates treatment. Inadequate treatment, treatment that fails to achieve goals, increases the risk for cardiovascular morbidity and mortality. From a clinical perspective, type 2 diabetes is a cardiovascular disease, an observation that is supported by a range of epidemiologic, postmortem, and cardiovascular imaging studies. Vascular wall dysfunction, and particularly endothelial dysfunction, has been posited as a "common soil" linking dysglycemic and cardiovascular diseases. Vascular wall dysfunction promoted by environmental triggers (e.g., sedentary lifestyle) and metabolic triggers (chronic hyperglycemia, obesity) has been associated with the upregulation of reactive oxygen species and chronic inflammatory and hypercoagulable states, and as such with the pathogenesis of type 2 diabetes, atherosclerosis, and cardiovascular disease. Glucagon-like peptide-1 (GLP)-1, an incretin hormone, and synthetic GLP-1 receptor agonists represent promising new areas of research and therapeutics in the struggle not only against type 2 diabetes but also against the cardiovascular morbidity and mortality associated with type 2 diabetes. In a number of small trials in humans, as well as in preclinical and in vitro studies, both native GLP-1 and GLP-1 receptor agonists have demonstrated positive effects on a range of cardiovascular disease pathologies and clinical targets, including such markers of vascular inflammation as high-sensitivity C-reactive protein, plasminogen activator inhibitor-1, and brain natriuretic peptide. Reductions in markers of dyslipidemia such as elevated levels of triglycerides and free fatty acids have also been observed, as have cardioprotective functions. Larger trials of longer duration will be required to confirm preliminary findings. In large human trials, GLP-1 receptor agonists have been associated with significant reductions in both blood pressure and weight.