Arterial wall thickness is associated with insulin resistance in type 2 diabetic patients

Detection of Early Vascular Atherosclerosis in Type 2 Diabetes Mellitus Using Ultrasound Radiofrequency-Data Technique

OBJECTIVES

To quantitatively evaluate changes in vascular elasticity and intima-media thickness (IMT) of the common carotid artery (CCA) with Ultrasound radiofrequency (RF)-data technology in asymptomatic patients with type-2 diabetes mellitus (T2DM) and controls.

MATERIALS AND METHODS

Thirty-seven T2DM patients and 39 controls were enrolled. Arterial elasticity and CCA-IMT were quantitatively assessed by RF-data technology. The CCA diameters in the diastolic and systolic phases, carotid distensibility (CD), IMT, values of stiffness (β) and local pulse wave velocity (PWVβ) were measured and compared between the two groups.

RESULTS

The T2DM group had significantly larger CCA diastolic and systolic diameter, lower CD values, higher IMT measurements (all p < 0.001), and higher values of β and PWVβ (all P < 0.05) than the controls. Significant differences were not revealed in the mean values of IMT, β, PWVβ and CD across both sides of the CCA (all P > 0.05).

CONCLUSIONS

Higher IMT measurement and lower arterial elasticity of the CCA are significantly pronounced in asymptomatic T2DM patients and may suggest atherosclerotic changes, and the ultrasound RF-data technique may be used as a potential approach for detection of early-stage atherosclerosis.

Dilating Vascular Diseases: Pathophysiology and Clinical Aspects

Atherosclerotic disease of the vessels is a significant problem affecting mortality and morbidity all over the world. However, dilatation of the vessels either in the arterial system or in the venous territory is another vessel disease. Varicocele, pelvic, and peripheral varicose veins and hemorrhoids are aneurysms of the venous vascular regions and have been defined as dilating venous disease, recently. Coronary artery ectasia, intracranial aneurysm, and abdominal aortic aneurysm are examples of arterial dilating vascular diseases. Mostly, they have been defined as variants of atherosclerosis. Although there are some similarities in terms of pathogenesis, they are distinct from atherosclerotic disease of the vessels. In addition, pathophysiological and histological similarities and clinical coexistence of these diseases have been demonstrated both in the arterial and in the venous system. This situation underlies the thought that dilatation of the vessels in any vascular territory should be considered as a systemic vessel wall disease rather than being a local disease of any vessel. These patients should be evaluated for other dilating vascular diseases in a systematic manner.

Visceral Adiposity is Preferentially Associated with Vascular Stiffness Rather than Thickness in Men with Type 2 Diabetes

Aim: Visceral fat accumulation is known to underlie the clustering of cardiovascular risk factors. However, it is not completely understood how visceral fat accumulation influences the development of cardiovascular disease. In this study, we investigated the clinical impact of visceral adiposity on vascular stiffness and thickness in patients with type 2 diabetes (T2D).

Methods: One hundred and sixty-one patients with T2D, including 92 men and 69 women, were included in this cross-sectional study. Visceral fat area (VFA) and subcutaneous fat area (SFA) were measured by dual bioelectrical impedance analysis. Stiffness parameter β and intima-media thickness (IMT) of the common carotid artery were measured by ultrasonography.

Results: The mean age and duration of diabetes in the study population were 61 years and 13.9 years, respectively. In men, VFA and waist circumference (WC) were positively correlated with stiffness parameter β, whereas body mass index (BMI), WC, and SFA were negatively correlated with IMT. In contrast, in women, none of the obesity-related indices were significantly correlated with stiffness parameter β or IMT. In multiple regression analyses, VFA as well as WC, BMI, and SFA were independently associated with stiffness parameter β after adjustment for age and other potential confounders in men but not in women. None of the obesity-related indices were independently associated with IMT for either sex.

Conclusion: In men with T2D, visceral adiposity is associated with carotid arterial stiffness but not thickness.

Early signs of atherosclerosis are associated with insulin resistance in non-obese adolescent and young adults with type 1 diabetes

Background

Patients with type 1 diabetes have a substantial risk of developing cardiovascular complications early in life. We aimed to explore the role of insulin sensitivity (S_i) as an early factor of atherosclerosis in young type 1 diabetes vs. non-diabetic subjects.

Methods

Forty adolescent and young adult individuals (20 type 1 diabetics and 20 non-diabetics), age 14–20 years, without characteristics of the metabolic syndrome, participated in this cross-sectional study. After an overnight fast, S_i was measured by hyperinsulinemic euglycemic clamp (40 mU/m²) and calculated by glucose infusion rate (GIR). Carotid intima-media thickness (cIMT) was measured in the common carotid artery with high-resolution ultrasonography. Risk factors of atherosclerosis (Body mass index [BMI], waist circumference, systolic blood pressure [sBP], triglycerides, low HDL-cholesterol and HbA_1c) were also investigated.

Results

cIMT was increased (0.52 ± 0.1 vs. 0.47 ± 0.1 mm, P < 0.01), whereas GIR was decreased (5.0 ± 2.1 vs. 7.1 ± 2.2 mg/kg/min, P < 0.01) in type 1 diabetics vs. non-diabetics. The differences in cIMT were negatively associated with S_i (r = −0.4, P < 0.01) and positively associated with waist circumference (r = 0.34, P = 0.03), with no such associations between BMI (r = 0.15, P = 0.32), sBP (r = 0.09, P = 0.58), triglycerides (r = 0.07, P = 0.66), HDL-cholesterol (r = 0.10, P = 0.55) and HbA_1c (r = 0.24, P = 0.13). In a multivariate regression model, between cIMT (dependent) and group (explanatory), only adjustment for S_i affected the significance (ß = 0.08, P = 0.11) vs. (ß = 0.07, P < 0.01) for the whole model. No interaction between cIMT, groups and S_i was observed.

Conclusions

cIMT is increased and associated with insulin resistance in adolescent, non-obese type 1 diabetic subjects. Although, no conclusions toward a causal relationship can be drawn from current findings, insulin resistance emerges as an important factor reflecting early signs of atherosclerosis in this small cohort.

Effects of cold pressor-induced sympathetic stimulation on the mechanical properties of common carotid and femoral arteries in healthy males

Our aim was to evaluate the effects of sympathetic excitation and elevation of blood pressure on mechanical properties of common carotid and femoral arteries by wave intensity analysis (WIA). The diameters and arterial stiffness parameters of right common carotid artery (RCCA) and right common femoral artery (RCFA) in healthy young men were measured by WIA at baseline and during cold pressor test (CPT). In addition, the blood pressure and heart rate were recorded simultaneously. The heart rates and blood pressures increased during CPT compared with baseline, while the pulse pressures remained unchanged. The diameters of RCCA increased slightly, while those of RCFA did not change. The Peterson's pressure modulus (Ep), augment index (AI), and pulse wave velocity from β (PWVβ) increased obviously, while arterial compliance (AC) decreased with no change in stiffness index (β) of both arteries during CPT when compared with baseline. There was an obvious increase in pulse wave velocity from wave intensity (PWV_WI) of RCCA, while the PWV_WI of RCFA showed no significant change during CPT. The sympathetic nervous system exerts a more marked tonic restraint on RCFA than on RCCA. The Ep, AC, AI, PWVβ of RCCA, and RCFA are much affected by variations in blood pressure and sympathetic status, while the β of both arteries are less vulnerable to these factors and are more reliable in reflecting the actual arterial stiffness; The PWV_WI appears to be suitable only for evaluating the stiffness of RCCA instead of RCFA.

Genetic risk factors and the anti-atherosclerotic effect of pioglitazone on carotid atherosclerosis of subjects with type 2 diabetes--a retrospective study

AIM

Pioglitazone, an agonist of peroxisome proliferator-activated receptor gamma, showed various anti-atherosclerotic effects on type 2 diabetic patients. This retrospective study was done to ascertain which risk factor(s) associate with anti-atherosclerotic effects of pioglitazone.

METHODS

We enrolled 160 diabetic patients treated through diet only and 62 treated with pioglitazone and annually evaluated carotid maximum (MaxIMT) and averaged intima-media thickness (AveIMT) for 2 years. We analyzed the relation of 99 single-nucleotide polymorphisms (SNP) as well as conventional risk factors with the progression or regression of carotid atherosclerosis.

RESULTS

The D allele of the angiotensin-converting enzyme (ACE) gene and 677 allele of the methylene-tetrahydrofolate reductase (MTHFR) gene showed a significant association with increases in MaxIMT among the diabetic subjects treated through diet only. The pioglitazone-treated carriers of the D allele showed an attenuation of MaxIMT as compared with the diet-treated carriers. The pioglitazone-treated carriers of the 677T allele carriers showed a significant attenuation of MaxIMT compared with the diet-treated carriers.

CONCLUSIONS

Pioglitazone may exert anti-atherosclerotic effects on type 2 diabetics carrying the ACE gene's D allele and/or MTHFR gene's 677T allele, who showed a progression of carotid atherosclerosis without the drug.

The combination of IMT and stiffness parameter beta is highly associated with concurrent coronary artery disease in type 2 diabetes

AIMS

The clinical implications of stiffness of the carotid artery (CA) have not been fully clarified in the prediction of coronary artery disease (CAD), although intima-media thickness (IMT) has been established as a surrogate marker. We examined the associations of stiffness parameter beta (ST) and IMT with concurrent CAD.

METHODS

IMT and ST were measured by ultrasound in 439 nondiabetic subjects as a control and 1528 type 2 diabetic subjects (T2DM) with or without CAD in a cross-sectional study.

RESULTS

Both IMT and ST significantly increased with age and group category, in the order of control, T2DM without CAD, and T2DM with CAD (p<0.001). The area under the curve on ROC analysis of ST for concurrent CAD was comparable to that for IMT. On multivariate logistic regression analysis, High IMT (>or=1.30 mm) and High stiffness (>or=20.0) had significant odds ratios for concurrent CAD (2.205, p<0.001 and 1.548, p<0.05, respectively). The group with High IMT and High Stiffness exhibited a stronger multivariate odds ratio (3.115, p=0.0001).

CONCLUSIONS

ST and IMT are associated with CAD and exhibited significant odds ratios for CAD. Our findings suggest that the combination of IMT and ST is a useful marker of atherosclerosis.

Insulin response to oral glucose load is associated with coronary artery disease in subjects with normal glucose tolerance

AIM

The critical role of hyperinsulinemia, independent of hyperglycemia, in the pathogenesis of atherosclerosis has not been fully determined. We investigated the association between secretion patterns of insulin after oral glucose load and the severity of coronary artery disease (CAD) in patients with normal glucose tolerance (NGT).

METHODS

We enrolled 116 subjects with NGT from 243 patients who had undergone coronary angiography and a standard 75-g oral glucose tolerance test. The patients were divided into 0-vessel, single-vessel and multi-vessel disease groups on the basis of the severity of CAD.

RESULTS

The 2-h insulin levels in the multi-vessel disease group (p=0.005) and the single-vessel disease group (p<0.05) were significantly higher than those in the 0-vessel disease group. Multivariate analysis revealed that the levels of 2-h insulin were an independent variable for the presence of CAD (p=0.02) after adjustment for gender and the presence of each criterion of metabolic syndrome using the definition of the International Diabetes Federation.

CONCLUSION

A slight but significant increase in prolonged insulin secretion, which is associated with the early stage of insulin resistance, in subjects with NGT, may play an important role in the pathogenesis of atherosclerosis.

The association of myeloperoxidase promoter polymorphism with carotid atherosclerosis is abolished in patients with type 2 diabetes

OBJECTIVES

Type 2 diabetes mellitus (DM) enhances the development of atherosclerosis and reduces the activity of the oxidative myeloperoxidase (MPO) enzyme. MPO gene has a functional promoter polymorphism -463G/A which leads to high- (GG) and low-expression (AG, AA) genotypes.

DESIGN AND METHODS

We studied the association of MPO polymorphism with carotid artery intima-media thickness (IMT) in 198 randomly selected Finnish men of Caucasian origin, 161 non-diabetics and 37 with type 2 DM. Their carotid IMT was measured by high-resolution ultrasonography, and the overall mean IMT value was calculated. MPO genotypes were determined by the PCR-RFLP method.

RESULTS

We found significant MPO genotype-by-study-group (control/DM) interactions with the overall mean IMT and internal carotid IMT (p=0.05 and p=0.04, respectively). Among non-diabetic subjects, the overall carotid IMT was 7.3% higher in subjects with the low-activity genotype when compared to the high-activity (G/G) group. The results remained significant after adjustment for total cholesterol and smoking (p=0.015). No similar genotypic association was found for the subjects with type 2 DM.

CONCLUSIONS

This data suggests that in subjects with normal glucose metabolism, MPO gene variation may modify the carotid artery IMT.

Increased arterial stiffness in normoglycemic normotensive offspring of type 2 diabetic parents

Diabetes is associated with a reduction of arterial distensibility. Limited information exists regarding whether or how early this appears in the course of the disease. We studied 54 normoglycemic, normotensive, healthy offspring of 2 parents with type 2 diabetes mellitus and 55 age- and sex-matched healthy control subjects. Carotid diastolic diameter and systodiastolic change were measured by echo tracking (Wall Track System) and wall thickness by echocolor Doppler (Sonos 5500, Philips). Pulse pressure was measured by a semiautomatic device positioned on the brachial artery and arterial distensibility calculated by Reneman formula. Blood pressure, blood glucose, glycohemoglobin, and insulin sensitivity (homeostasis model assessment index) were normal or only slightly elevated and by and large similar in the 2 groups. Compared with control subjects, offspring of diabetic parents showed similar carotid diameters at diastole and a reduced increase in carotid diameter at systole (-16%), a reduced carotid artery distensibility (-30%), and an increased pulse pressure (+21.8%), all differences being statistically significant (P<0.05) and persisting in subgroups with elevated or normal body mass index values (<25 and >or=25 kg/m(2)). Carotid artery wall thickness was not different between the 2 groups. Thus, subjects with predisposition to diabetes show carotid artery stiffening even in the absence of blood pressure alterations, as well as substantial alterations of glucose metabolism, body mass index, and changes in carotid wall thickness. This suggests that, in diabetes, alterations in arterial mechanical properties represent an early phenomenon, which may occur in the absence of metabolic and blood pressure alterations.

Novel insights into an old controversy: is coronary artery ectasia a variant of coronary atherosclerosis?

Coronary artery ectasia (CAE) is defined as a localized or diffuse non-obstructive lesion of the epicardial coronary arteries with a luminal dilation exceeding 1.5-fold the diameter of the normal adjacent arterial segment. The incidence of CAE has been reported to range between 2% and 4%, which might be an overestimation of the true frequency. The coincidence of CAE with other systemic vascular dilatations has suggested that the mechanism underlying CAE is not only localized to coronary arteries, but also to other vascular compartments such as aorta or peripheral veins. Although the pathophysiology of CAE remains largely unknown, it was supposed to represent a variant of coronary atherosclerosis. This review focuses on this controversy of whether CAE and coronary artery disease (CAD) are two manifestations of the same underlying process. There are clear differences between CAD and CAE with respect to cardiovascular risk factors such as diabetes mellitus, and pathogenic steps in disease progress such as inflammation or extracellular matrix remodeling. As this review will underscore, the current knowledge of the field is insufficient to finally clarify the causative interrelation between CAE and CAD. The clinical course and treatment of CAE mainly depends on its coexistence with CAD. When coexisting with CAD, the prognosis and treatment of CAE are the same as for CAD alone. In isolated CAE, prognosis is better and anti-platelet drugs are the mainstay of treatment. Surgical treatment can be considered in selected patients. For clarifying the mechanism underlying CAE, additional clinical, histopathological and pathophysiological investigations are required. In fact, every patient with CAE should be evaluated systematically for pathological changes in other vascular territories, both in the arterial system as well as in the venous system, which might occur in the disease process.

Noninvasive assessment of preclinical atherosclerosis

Initially considered as a semipermeable barrier separating lumen from vessel wall, the endothelium is now recognised as a complex endocrine organ responsible for a variety of physiological processes vital for vascular homeostasis. These include the regulation of vascular tone, luminal diameter, and blood flow; hemostasis and thrombolysis; platelet and leucocyte vessel-wall interactions; the regulation of vascular permeability; and tissue growth and remodelling. The endothelium modulates arterial stiffness, which precedes overt atherosclerosis and is an independent predictor of cardiovascular events. Unsurprisingly, dysfunction of the endothelium may be considered as an early and potentially reversible step in the process of atherogenesis and numerous methods have been developed to assess endothelial status and large artery stiffness. Methodology includes flow-mediated dilatation of the brachial artery, assessment of coronary flow reserve, carotid intimamedia thickness, pulse wave analysis, pulse wave velocity, and plethysmography. This review outlines the various modalities, indications, and limitations of available methods to assess arterial dysfunction and vascular risk.

The metabolic syndrome and the Maillard reaction. An introduction

With the rapid increase of life expectancy in western societies, appeared also a new phenomenon, obesity, which took during the recent decades pandemic dimensions. One of the consequences was the appearance of type II diabetes in much younger persons than before. The result of intensive research in this field over the last decades led, among other achievements to the identification of biological and molecular symptoms which together were reclassified as the "metabolic syndrome". Questionable as far as its originality is concerned, it did however good service to practitioners by formulating criteria for diagnostic and therapeutical purposes. Among the underlying biochemical mechanisms the Maillard reaction, the non enzymatic glycosylation of proteins and nucleotide bases followed by the formation of advanced glycation and products (AGE-s) plays an important role. Several recent experimental results confirm this statement, some of them are published in this issue. The reviews and original contributions form together an up to date report on this important pathology and support again the importance of posttranslational and environmental factors influencing gene expression and cellular functions.

Effect of adiponectin on carotid arterial stiffness in type 2 diabetic patients treated with pioglitazone and metformin

Adiponectin, an adipocyte-specific plasma protein, has been reported to exhibit protective effects against atherosclerosis as well as an insulin-sensitizing effect. This study was designed to investigate the effect of adiponectin on carotid arterial stiffness in type 2 diabetic patients treated with pioglitazone and metformin. Twenty type 2 diabetic patients were enrolled and divided into 2 groups, a pioglitazone-treated group (n = 10) and a metformin-treated group (n = 10). Before and after intervention, plasma adiponectin levels were measured by enzyme-linked immunosorbent assay and carotid arterial stiffness was evaluated by the stiffness parameter beta, measured by ultrasound equipped with a phase-locked echo-tracking system. In the pioglitazone group, plasma adiponectin level significantly increased and stiffness parameter beta significantly decreased, whereas in the metformin group neither of these parameters changed significantly. The changes in stiffness parameter beta were significantly and inversely correlated with change in plasma adiponectin level after treatment with pioglitazone or metformin in the group of all subjects (r = -0.472, P = .036). In conclusion, the present study is the first to demonstrate that increase in adiponectin level after treatment with the insulin sensitizers pioglitazone and metformin may improve arterial stiffness in patients with type 2 diabetes mellitus.

Comparison of body fat composition and serum adiponectin levels in diabetic obesity and non-diabetic obesity

OBJECTIVE

Clinical aspects of diabetes and obesity are somewhat different, even at similar levels of insulin resistance. The purpose of this study was to determine differences in body fat distribution and serum adiponectin concentrations in diabetic and non-diabetic obese participants. We were also interested in identifying the characteristics of insulin resistance in these two groups, particularly from the standpoint of adiponectin.

RESEARCH METHODS AND PROCEDURES

Adiponectin concentrations of 112 type 2 diabetic obese participants and 124 non-diabetic obese participants were determined. Abdominal adipose tissue areas and midthigh skeletal muscle areas were measured by computed tomography. A homeostasis model assessment of the insulin resistance score was calculated to assess insulin sensitivity. The relationships among serum adiponectin, body fat distribution, and clinical characteristics were also analyzed.

RESULTS

Both abdominal subcutaneous and visceral fat areas were higher in the non-diabetic obese group, whereas midthigh low-density muscle area was higher in the diabetic obese group. The homeostasis model assessment of the insulin resistance score was similar between groups, whereas serum adiponectin was lower in the diabetic obese group. Abdominal visceral fat (beta = -0.381, p = 0.012) was a more important predictor of adiponectin concentration than low-density muscle (beta = -0.218, p = 0.026) in cases of non-diabetic obesity, whereas low-density muscle (beta = -0.413, p = 0.013) was a better predictor of adiponectin level than abdominal visceral fat (beta = - 0.228, p = 0.044) in diabetic obese patients.

DISCUSSION

Therefore, factors involved in pathophysiology, including different serum adiponectin levels and body fat distributions, are believed to be responsible for differences in clinical characteristics, even at similar levels of insulin resistance in both diseases.

Relationship between insulin resistance and effect of atorvastatin in non-diabetic subjects

BACKGROUND

Although insulin resistance (IR) is present in non-diabetic subjects, it is unknown whether IR affects statin treatment. We assessed the relationship between IR and the changes of lipid profile in patients with hyperlipidemia treated by atorvastatin.

METHODS

Forty-four non-diabetic patients were included. Homeostasis model assessment of insulin resistance (HOMA-IR) was calculated. We used the value of 2.5 as the threshold for IR.

RESULTS

High-density lipoprotein (HDL) cholesterol at baseline was lower and triglyceride (TG) at baseline was higher in the IR group than in the nonIR group (p < 0.05). Changes in all lipid measurements did not differ between the two groups. HOMA-IR was correlated with HDL cholesterol at baseline and at follow-up and correlated with TG at baseline and at follow-up (r = -0.40, r = -0.53, r = 0.38, r = 0.35, p < 0.01, respectively). However, HOMA-IR did not associate with changes in total cholesterol, low-density lipoprotein cholesterol, HDL cholesterol, and TG.

CONCLUSION

The IR did not affect the degree of reduction in cholesterol by atorvastatin in non-diabetic subjects. The IR may influence hypertriglyceridemia greater than the effect of atorvastatin in non-diabetic subjects.

The K469E polymorphism of the intercellular adhesion molecule-1 gene is associated with plasma fibrinogen level in type 2 diabetes

Intercellular adhesion molecule-1 (ICAM-1) is involved in inflammation and development of atherosclerotic change of vascular endothelium. The aim of the present study is to investigate whether K469E polymorphism of the ICAM-1 gene is associated with various clinical factors including plasma fibrinogen in patients with type 2 diabetes. ICAM-1 gene polymorphism was examined using polymerase chain reaction and restriction enzyme analysis in 360 type 2 diabetic patients. Plasma fibrinogen levels and other clinical variables were measured as well as circulating soluble ICAM-1 (sICAM-1) levels by enzyme-linked immunosorbent assay. The distribution of ICAM-1 genotypes, EE, EK, and KK, was not significantly different between type 2 diabetes and 152 healthy control subjects. Among 3 groups according to ICAM-1 genotypes in type 2 diabetes, no difference was found in adiposity, glycemic control, lipid profile, insulin sensitivity evaluated by homeostasis model assessment, or sICAM-1. Regarding fibrinogen, the patients with E allele showed significantly lower plasma fibrinogen levels in a dose-dependent manner (P = .033). Spearman rank correlation analyses revealed that ICAM-1 genotype showed significant correlation with plasma fibrinogen level (P < .001). In multiple regression analysis, ICAM-1 genotype was independent contribution factor of plasma fibrinogen level as well as high-density lipoprotein-cholesterol and urinary albumin excretion (R2 = 0.148, P < .001). In conclusion, K469E polymorphism of the ICAM-1 gene had impact on plasma fibrinogen level independently of other clinical factors in 360 type 2 diabetic patients, suggesting that fibrinogen is a candidate which links the ICAM-1 gene polymorphism to atherosclerosis.

Asymmetric dimethylarginine: A molecule responsible for the coexistence of insulin resistance and atherosclerosis via dual nitric oxide synthase inhibition

Asymmetric dimethylarginine (ADMA) has been recently identified as the major endogenous inhibitor of soluble nitric oxide synthase. Its systemic accumulation was observed in conjunction with atherosclerosis and several cardiovascular and metabolic diseases. Here, we propose that ADMA causes insulin resistance by the inhibition of the neuronal isoform of nitric oxide synthase, while the simultaneously observed atherosclerosis is the consequence of endothelial nitric oxide synthase (NOS) inhibition. Our hypothesis rests on animal models in which experimental insulin resistance was induced by intraportal administration of non-selective and selective neuronal nitric oxide synthase inhibitors, N-methyl-L-arginine (L-NMMA) or 7-nitroindazole. In these models, loss of hepatic nitric oxide productions is presumed to hinder a very potent insulin sensitizing mechanism referred to as meal induced sensitization that is anatomically linked to the nitrergic fibers of the anterior hepatic plexus. Cause and effect relationship between ADMA and insulin resistance has been proposed previously by others however the nature of this relationship has not been elucidated in detail. In our hypothesis, we suggest that ADMA by inhibiting both the neuronal and the endothelial forms of NOS, results both in insulin resistance and in accelerated atherosclerosis, therefore ADMA is the molecule responsible for the coexistence of these two conditions. We also suggest animal models and human studies to test our hypothesis, the results of which may offer novel approaches in the prevention of insulin resistance and atherosclerosis.

Short-term aerobic exercise improves arterial stiffness in type 2 diabetes

OBJECTIVE

To investigate whether: (1) aerobic exercise decreases arterial stiffness and (2) reduction in arterial stiffness is associated with improvement in insulin resistance in type 2 diabetes.

METHODS

Common carotid and femoral arterial stiffness was ultrasonographically evaluated using stiffness index beta in 23 type 2 diabetic subjects before and after a 3-week exercise protocol including ergometer and walking. Insulin sensitivity (Clamp-IR) was assessed using euglycemic-hyperinsulinemic clamp before and after the protocol. Arterial stiffness was also examined in steady hyperinsulinemic state during clamp.

RESULTS

Anthropometrical factors did not change following exercise. Clamp-IR tended to increase after exercise protocol (P = 0.061). Stiffness index beta decreased following exercise in both common carotid and femoral arteries (P = 0.020 and P < 0.001, respectively). DeltaClamp-IR was significantly correlated with the changes in stiffness index beta of both common carotid (P = 0.040) and femoral artery (P = 0.016). Divided into tertiles according to DeltaClamp-IR, decreases in stiffness index beta for both common carotid (P = 0.009) and femoral (P = 0.037) arteries was greater in tertile group with a higher DeltaClamp-IR. Hyperinsulinemia during clamp decreased stiffness index beta in both common carotid (P = 0.031) and femoral (P = 0.025) arteries before exercise, but these effects disappeared after the exercise protocol.

CONCLUSIONS

Short-term aerobic exercise significantly decreased arterial stiffness in both common carotid and femoral arteries, and the reduction of stiffness was associated with improvement of insulin resistance in type 2 diabetes.

Role of surrogate markers in assessing patients with diabetes mellitus and the metabolic syndrome and in evaluating lipid-lowering therapy

Diabetes mellitus and the metabolic syndrome (MS) are reaching epidemic proportions in the United States, and cardiovascular disease continues to be the leading cause of death among patients with diabetes. A range of noninvasive screening tools may help reduce the morbidity and mortality of patients with diabetes because of early detection of subclinical cardiovascular disease and active monitoring of the effectiveness of therapy. Surrogate markers of subclinical disease include conventional and contrast-enhanced ultrasound imaging of carotid artery intima-media thickness (c-IMT), 2-dimensional echocardiography, coronary artery calcium imaging, cardiac magnetic resonance imaging, ankle-brachial indices, and brachial artery reactivity testing. Because these noninvasive imaging tools are relatively comfortable and entail relatively low risk to the patient, they are ideal for initial screening and for the repeated imaging that is required for monitoring the effectiveness of therapy. Moreover, when used in large numbers of patients with diabetes, prediabetes, and the MS, these imaging tools may be useful in developing and validating thresholds for the use of lipid-lowering therapy as well as clear therapeutic goals for this population. In addition, contrast-enhanced c-IMT scans now produce real-time images of the vasa vasorum and neovascularization of atherosclerotic plaque, potentially causing a paradigm shift in our view of the genesis of atherosclerosis and affecting treatment options for all populations. Thus, surrogate markers may not only help improve individual patient outcomes, they also may help direct scarce medical resources to maximize medical benefits, improve overall medical care, and minimize costs and untoward side effects.