Influence of insulin and of insulin resistance on platelet and vascular smooth muscle cell function

Predictive value of platelet distribution width on organ damage in patients with metabolic syndrome: a retrospective case-control study

OBJECTIVES

Metabolic syndrome (MS) is a cluster of metabolic disorders characterized by damage to multiple organs. Platelet distribution width (PDW) has been used to assess the progression of several metabolic disorders, including left ventricular hypertrophy (LVH) and diabetic nephropathy (DN). Therefore, this study aimed to evaluate the predictive value of PDW in relation to organ damage in patients with MS.

METHODS

The study included 151 patients with MS and 113 healthy controls. Clinicopathological data, including sex, age, abdominal circumference, blood pressure, and body mass index (BMI), were collected. The predictive potential of PDW was assessed by analyzing its correlation with MS progression, LVH, atherosclerosis, and kidney function.

RESULTS

The analysis revealed that patients in the MS group had higher levels of BMI, abdominal circumference, systolic blood pressure (SBP), diastolic blood pressure (DBP), triglycerides (TG), and fasting plasma glucose (FPG), and lower levels of high-density lipoprotein cholesterol (HDL-C), compared with controls. PDW was positively correlated with BMI, abdominal circumference, SBP, DBP, and FPG, and negatively correlated with HDL-C. FPG, SBP, and HDL-C were identified as independent parameters contributing to changes in PDW. Furthermore, heart function was positively related to PDW levels, while kidney function was negatively related. Logistic regression analysis further demonstrated that PDW was an independent risk factor for LVH, atherosclerosis, and kidney dysfunction.

CONCLUSIONS

PDW could serve as a promising predictive indicator for organ damage associated with the progression of MS.

Triglyceride-glucose index is associated with microcirculatory resistance in patients with type 2 diabetes and STEMI undergoing primary PCI

The triglyceride-glucose (TyG) index is emerging as a promising marker for insulin resistance and serves as an independent risk predictor for cardiovascular outcomes. The coronary angiography-derived index of microcirculatory resistance (AMR) is computed to evaluate coronary microcirculation. However, the association between the TyG index and the AMR in patients with type 2 diabetes mellitus (T2DM) and ST-segment elevation myocardial infarction (STEMI) remains unclear. We consecutively recruited 168 patients with T2DM and STEMI who underwent primary percutaneous coronary intervention (pPCI) at Taizhou People's Hospital from January 2022 to December 2023. Patients were classified into low AMR group (AMR < 2.5) and high AMR group (AMR ≥ 2.5). The TyG index was calculated using the formula: ln [plasma triglyceride (mg/dL) × fasting blood glucose (mg/dL)/2]. The study enrolled 81 patients in the low AMR group and 87 in the high AMR group, with the TyG index being significantly higher in the high AMR group. Multivariable logistic regression analysis revealed a significant association between the TyG index and high AMR after adjusting for confounding variables (odds ratio: 2.449, 95% confidence interval: 1.421-4.220, and p = 0.001). The area under the curve for the TyG index predicting high AMR was 0.650 (95% confidence interval: 0.57-0.73, p < 0.001), with a cut-off value of 9.57. Our findings indicate that the TyG index is significantly associated with AMR in T2DM patients with STEMI undergoing pPCI, suggesting it may serve as a valuable predictor of high AMR in this population.

The Interplay between Liver Sinusoidal Endothelial Cells, Platelets, and Neutrophil Extracellular Traps in the Development and Progression of Metabolic Dysfunction-Associated Steatotic Liver Disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) represents a societal burden due to the lack of effective treatment and incomplete pathophysiology understanding. This review explores the intricate connections among liver sinusoidal endothelial cells (LSECs), platelets, neutrophil extracellular traps (NETs), and coagulation disruptions in MASLD pathogenesis. In MASLD's early stages, LSECs undergo capillarization and dysfunction due to excessive dietary macronutrients and gut-derived products. Capillarization leads to ischemic changes in hepatocytes, triggering pro-inflammatory responses in Kupffer cells (KCs) and activating hepatic stellate cells (HSCs). Capillarized LSECs show a pro-inflammatory phenotype through adhesion molecule overexpression, autophagy loss, and increased cytokines production. Platelet interaction favors leucocyte recruitment, NETs formation, and liver inflammatory foci. Liver fibrosis is facilitated by reduced nitric oxide, HSC activation, profibrogenic mediators, and increased angiogenesis. Moreover, platelet attachment, activation, α-granule cargo release, and NETs formation contribute to MASLD progression. Platelets foster fibrosis and microthrombosis, leading to parenchymal extinction and fibrotic healing. Additionally, platelets promote tumor growth, epithelial-mesenchymal transition, and tumor cell metastasis. MASLD's prothrombotic features are exacerbated by insulin resistance, diabetes, and obesity, manifesting as increased von Willebrand factor, platelet hyperaggregability, hypo-fibrinolysis, and a prothrombotic fibrin clot structure. Improving LSEC health and using antiplatelet treatment appear promising for preventing MASLD development and progression.

The Combined Effect of Systemic Immune-Inflammation Index and Type 2 Diabetes Mellitus on the Prognosis of Patients Undergoing Percutaneous Coronary Intervention: A Large-Scale Cohort Study

Background

Chronic low-grade inflammation is the common mechanism of both atherosclerosis and type 2 diabetes mellitus (T2DM), and systemic immune-inflammation index (SII) has been emerged as a novel and simple inflammatory biomarker. However, the association between SII and glycemic metabolism and their synergetic effect on the prognosis of coronary artery disease (CAD) patients remains unclear.

Methods

A total of 8602 patients hospitalized for percutaneous coronary intervention (PCI) were included. The primary endpoint was major adverse cardiovascular events (MACE), including all-cause death, myocardial infarction (MI), and target vessel revascularization. According to the optimal cut-off value of SII for MACEs, patients were grouped into higher levels of SII (SII-H) and lower levels of SII (SII-L) and further divided by the concomitance of T2DM into four groups: SII-H/T2DM, SII-H/Non-T2DM, SII-L/T2DM, SII-L/Non-T2DM.

Results

During a median 2.4-year follow-up, 522 MACEs occurred. The optimal cut-off value of SII for MACEs was 502.5. A 1-unit increase of SII (transformed by natural logarithm) was associated with a 29% increase of MACE risks in the T2DM cohort [adjusted hazard ratio (HR): 1.29, 95% confidence interval (CI): 1.03 to 1.61, P = 0.024], while had no effect in the non-T2DM cohort (HR: 1.03, 95% CI: 0.80 to 1.34, P = 0.800). Compared to those in SII-H/T2DM group, patients in SII-H/Non-T2DM, SII-L/T2DM, SII-L/Non-T2DM had significantly decreased risk of MACEs [adjusted HR: 0.77, 95% CI: 0.61 to 0.98, P = 0.036; adjusted HR: 0.66, 95% CI: 0.50 to 0.87, P = 0.003; adjusted HR: 0.58, 95% CI: 0.45 to 0.74, P < 0.001; respectively]. Multivariable Cox regression analysis also indicated the highest risk in T2DM patients with higher levels of SII than others (P for trend < 0.001).

Conclusion

In this large-scale real-world study, diabetic patients with elevated SII levels were associated with worse clinical outcomes after PCI.

Urine 11-Dehydro-Thromboxane B2 in Aspirin-Naive Males with Metabolic Syndrome

Urine 11-dehydro-thromboxane B2 (11-dehydro-TXB2), an indirect measure of platelet activity, is elevated in cardiovascular diseases and diabetes. The purpose of our study was to determine whether urine 11-dehydro-TXB2 is elevated in aspirin-naive males with metabolic syndrome (MS) and to determine predictors of 11-dehydro-TXB2 levels. The secondary aim was to evaluate whether these MS patients could be potential candidates for the aspirin-mediated prevention of atherosclerotic cardiovascular diseases (ASCVDs). In 82 males with MS (76 hypertensive), anthropometric measures, urine 11-dehydro-TXB2, platelet count, creatinine, glucose, insulin, estimated insulin resistance, lipid parameters, high-sensitivity C-reactive protein (hs-CRP), adiponectin, homocysteine, and ten-year risk of fatal cardiovascular disease (SCORE) were assessed. Urine 11-dehydro-TXB2 levels were elevated (≥2500 pg/mg creatinine) in two-thirds of patients, including 11 high-risk patients (SCORE ≥ 5%). Homocysteine, adiponectin, hs-CRP, waist-to-hip ratio, and total cholesterol were found to be predictors of urine 11-dehydro-TXB2. In conclusion, there is a high incidence of elevated urine 11-dehydro-TXB2 in males with MS, including in some patients who are at a high or very high risk of ASCVDs. 11-dehydro-TXB2 levels are associated with hyperhomocysteinemia, inflammation, fat distribution, hypercholesterolemia, and adiponectin concentrations. Elevated 11-dehydro-TXB2 levels may support the use of personalised aspirin ASCVD prevention in high-risk males with MS. Giuseppe Patti.

An Insight into Recent Advances on Platelet Function in Health and Disease

Platelets play a variety of roles in vascular biology and are best recognized as primary hemostasis and thrombosis mediators. Platelets have a large number of receptors and secretory molecules that are required for platelet functionality. Upon activation, platelets release multiple substances that have the ability to influence both physiological and pathophysiological processes including inflammation, tissue regeneration and repair, cancer progression, and spreading. The involvement of platelets in the progression and seriousness of a variety of disorders other than thrombosis is still being discovered, especially in the areas of inflammation and the immunological response. This review represents an integrated summary of recent advances on the function of platelets in pathophysiology that connects hemostasis, inflammation, and immunological response in health and disease and suggests that antiplatelet treatment might be used for more than only thrombosis.

Impairment of Anti-Aggregatory Responses to Nitric Oxide and Prostacyclin: Mechanisms and Clinical Implications in Cardiovascular Disease

The propensity towards platelet-rich thrombus formation increases substantially during normal ageing, and this trend is mediated by decreases in platelet responsiveness to the anti-aggregatory nitric oxide (NO) and prostacyclin (PGI2) pathways. The impairment of soluble guanylate cyclase and adenylate cyclase-based signalling that is associated with oxidative stress represents the major mechanism of this loss of anti-aggregatory reactivity. Platelet desensitization to these autacoids represents an adverse prognostic marker in patients with ischemic heart disease and may contribute to increased thrombo-embolic risk in patients with heart failure. Patients with platelet resistance to PGI2 also are unresponsive to ADP receptor antagonist therapy. Apart from ischemia, diabetes and aortic valve disease are also associated with impaired anti-aggregatory homeostasis. This review examines the association of impaired platelet cyclic nucleotide (i.e., cGMP and cAMP) signalling with the emerging evidence of thromboembolic risk in cardiovascular diseases, and discusses the potential therapeutic strategies targeting this abnormality.

The Association Between Arterial Stiffness and Muscle Indices Among Healthy Subjects and Subjects With Cardiovascular Risk Factors: An Evidence-Based Review

Skeletal muscle is one of the major tissues in the body and is important for performing daily physical activity. Previous studies suggest that vascular dysfunction contributes to reduced skeletal muscle mass. However, the association between vascular dysfunction and muscle mass, muscle strength and muscle flexibility are less established. Therefore, the focus of this review was to investigate the association between arterial stiffness (AS) which is a marker of vascular function, and muscle indices among healthy and those with cardiovascular risk factors. Three databases were used to search for relevant studies. These keywords were used: "arterial stiffness" OR "vascular stiffness" OR "aortic stiffness" OR "pulse wave velocity" OR "carotid femoral pulse wave velocity" OR "pulse wave analysis" AND "muscle" OR "skeletal" OR "flexibility" OR "range of motion" OR "articular" OR "arthrometry" OR "strength" OR "hand strength" OR "pinch strength" OR "mass" OR "lean" OR "body composition." The criteria were; (1) original, full-text articles, (2) articles written in English language, (3) human studies involving healthy adults and/or adults with cardiovascular disease (CVD) or CVD risk factors (4) articles that reported the relationship between AS (measured as carotid-femoral pulse wave velocity or brachial-ankle pulse wave velocity) and muscle indices (measured as muscle mass, muscle flexibility and muscle strength) after adjusting for relevant confounders. The search identified 2295 articles published between 1971 and June 2021. Only 17 articles fulfilled the criteria. Two studies showed an inverse association between AS and muscle strength in healthy subjects, whereas in subjects with CVD risk factors, five out of seven studies found an inverse correlation between the two parameters. Eleven studies showed an inverse association between AS and muscle mass in subjects with CVD and CVD risk factors. The association between AS and muscle flexibility was not studied in any of the articles reviewed. In conclusion, there is an inverse correlation between muscle indices and AS in healthy adults and those with CVD or CVD risk factors. However, most of the studies were cross-sectional studies, hence the need for future prospective studies to address this issue.

Platelet Function in Cardiovascular Disease: Activation of Molecules and Activation by Molecules

Globally, one of the major causes of death is the cardiovascular disease (CVD), and platelets play an important role in thrombosis and atherosclerosis that led to death. Platelet activation can be done by different molecules, genes, pathways, and chemokines. Lipids activate platelets by inflammatory factors, and platelets are activated by receptors of peptide hormones, signaling and secreted proteins, microRNAs (miRNAs), and oxidative stress which also affect the platelet activation in older age. In addition, surface molecules on platelets can interact with other cells and chemokines in activated platelets and cause inflammation thrombosis events and CVD. However, these molecules activating platelets or being activated by platelets can be suggested as the markers to predict the clinical outcome of CVD and can be targeted to reduce thrombosis and atherosclerosis. However, hindering these molecules by other factors such as genes and receptors can reduce platelet activation and aggregation and targeting these molecules can control platelet interactions, thrombosis, and CVD. In addition, dual therapy with the receptor blockers and novel drugs results in better management of CVD patients. Overall, our review will emphasize on the molecules involved in the activation of platelets and on the molecules that are activated by platelets in CVD and discuss the molecules that can be blocked or targeted to reduce the thrombosis events and control CVD.

Diabetes and atherothrombosis: The circadian rhythm and role of melatonin in vascular protection

Obesity-related euglycaemic insulin resistance clusters with cardiometabolic risk factors, contributing to the development of both type 2 diabetes and cardiovascular disease. An increased thrombotic tendency in diabetes stems from platelet hyperactivity, enhanced activity of prothrombotic coagulation factors and impaired fibrinolysis. Furthermore, a low-grade inflammatory response and increased oxidative stress accelerate the atherosclerotic process and, together with an enhanced thrombotic environment, result in premature and more severe cardiovascular disease. The disruption of circadian cycles in man secondary to chronic obesity and loss of circadian cues is implicated in the increased risk of developing diabetes and cardiovascular disease. Levels of melatonin, the endogenous synchronizer of circadian rhythm, are reduced in individuals with vascular disease and those with deranged glucose metabolism. The anti-inflammatory, antihypertensive, antioxidative and antithrombotic activities of melatonin make it a potential therapeutic agent to reduce the risk of vascular occlusive disease in diabetes. The mechanisms behind melatonin-associated reduction in procoagulant response are not fully known. Current evidence suggests that melatonin inhibits platelet aggregation and might affect the coagulation cascade, altering fibrin clot structure and/or resistance to fibrinolysis. Large-scale clinical trials are warranted to investigate the effects of modulating the circadian clock on insulin resistance, glycaemia and cardiovascular outcome.

Thrombosis in diabetes: a shear flow effect?

Cardiovascular events are the major cause of morbidity and mortality in Type 2 diabetes (T2D). This condition is associated with heightened platelet reactivity, contributing to increased atherothrombotic risk. Indeed, individuals with diabetes respond inadequately to standard antiplatelet therapy. Furthermore, they often experience recurrent events as well as side effects that include excess bleeding. This highlights the need for identification of novel regulators of diabetes-associated thrombosis to target for therapeutic intervention. It is well established that platelet aggregation, a process essential for thrombus formation, is tightly regulated by shear stress; however, the mechanisms underlying shear activation of platelets, particularly in the setting of diabetes, are still poorly understood. This review will address the limitations of current diagnostic systems to assess the importance of shear stress in the regulation of thrombus formation in T2D, and the inability to recapitulate the pro-thrombotic phenotype seen clinically in the setting of T2D. Moreover, we will discuss recent findings utilizing new technologies to define the importance of shear stress in thrombus formation and their potential application to the setting of diabetes. Finally, we will discuss the potential of targeting shear-dependent mechanisms of thrombus formation as a novel therapeutic approach in the setting of T2D.

Atherosclerosis in Type 2 Diabetes Mellitus: The Role of Insulin Resistance

Type 2 diabetes mellitus is associated with a marked increase in the risk of atherosclerotic diseases, including coronary heart disease, peripheral arterial disease, and cerebrovascular disease. Insulin resistance is a key factor in the pathogenesis of type 2 diabetes mellitus. Insulin resistance and its attendant metabolic abnormalities may cause much of the increased cardiovascular risk of type 2 diabetes mellitus. Among the abnormalities associated with insulin resistance are dyslipidemia, hypertension, systemic inflammation, and a prothrombotic state. This review discusses the role that each of these disorders plays in the cardiovascular risk of type 2 diabetes mellitus.

Skeletal Muscle Vascular Function: A Counterbalance of Insulin Action

Insulin is a vasoactive hormone that regulates vascular homeostasis by maintaining balance of endothelial-derived NO and ET-1. Although there is general agreement that insulin resistance and the associated hyperinsulinemia disturb this balance, the vascular consequences for hyperinsulinemia in isolation from insulin resistance are still unclear. Presently, there is no simple answer for this question, especially in a background of mixed reports examining the effects of experimental hyperinsulinemia on endothelial-mediated vasodilation. Understanding the mechanisms by which hyperinsulinemia induces vascular dysfunction is essential in advancing treatment and prevention of insulin resistance-related vascular complications. Thus, we review literature addressing the effects of hyperinsulinemia on vascular function. Furthermore, we give special attention to the vasoregulatory effects of hyperinsulinemia on skeletal muscle, the largest insulin-dependent organ in the body. This review also characterizes the differential vascular effects of hyperinsulinemia on large conduit vessels versus small resistance microvessels and the effects of metabolic variables in an effort to unravel potential sources of discrepancies in the literature. At the cellular level, we provide an overview of insulin signaling events governing vascular tone. Finally, we hypothesize a role for hyperinsulinemia and insulin resistance in the development of CVD.

Platelets and diabetes mellitus

Platelet activation plays a key role in atherothrombosis in type 2 diabetes mellitus (T2DM) and increased in vivo platelet activation with enhanced thromboxane (TX) biosynthesis has been reported in patients with impairment of glucose metabolism even in the earlier stages of disease and in the preclinical phases. In this regards, platelets appear as addresses and players carrying and transducing metabolic derangement into vascular injury. The present review critically addresses key pathophysiological aspects including (i) hyperglycemia, glycemic variability and insulin resistance as determinants and predictors of platelet activation, (ii) inflammatory mediators derived from platelets, such as soluble CD40 ligand, soluble CD36, Dickkopf-1 and probably soluble receptor for advanced glycation-end-products (sRAGE), which expand the functional repertoire of platelets from players of hemostasis and thrombosis to powerful amplifiers of inflammation by promoting the release of cytokines and chemokines, cell activation, and cell-cell interactions; (iii) molecular mechanisms underpinning the less-than-expected antithrombotic protection by aspirin (ASA), despite regular antiplatelet prophylaxis at the standard dosing regimen, and (iv) stratification of patients deserving different antiplatelet strategies, based on the metabolic phenotype. Taken together, these pathophysiological aspects may contribute to the development of promising mechanism-based therapeutic strategies to reduce the progression of atherothrombosis in diabetic subjects.

Essential role of Pin1 via STAT3 signalling and mitochondria-dependent pathways in restenosis in type 2 diabetes

Type 2 diabetes (T2D) is associated with accelerated restenosis rates after angioplasty. We have previously proved that Pin1 played an important role in vascular smooth muscle cell (VSMC) cycle and apoptosis. But neither the role of Pin1 in restenosis by T2D, nor the molecular mechanism of Pin1 in these processes has been elucidated. A mouse model of T2D was generated by the combination of high-fat diet (HFD) and streptozotocin (STZ) injections. Both Immunohistochemistry and Western blot revealed that Pin1 expression was up-regulated in the arterial wall in T2D mice and in VSMCs in culture conditions mimicking T2D. Next, increased activity of Pin1 was observed in neointimal hyperplasia after arterial injury in T2D mice. Further analysis confirmed that 10% serum of T2D mice and Pin1-forced expression stimulated proliferation, inhibited apoptosis, enhanced cell cycle progression and migration of VSMCs, whereas Pin1 knockdown resulted in the converse effects. We demonstrated that STAT3 signalling and mitochondria-dependent pathways played critical roles in the involvement of Pin1 in cell cycle regulation and apoptosis of VSMCs in T2D. In addition, VEGF expression was stimulated by Pin1, which unveiled part of the mechanism of Pin1 in regulating VSMC migration in T2D. Finally, the administration of juglone via pluronic gel onto injured common femoral artery resulted in a significant inhibition of the neointima/media ratio. Our findings demonstrated the vital effect of Pin1 on the VSMC proliferation, cell cycle progression, apoptosis and migration that underlie neointima formation in T2D and implicated Pin1 as a potential therapeutic target to prevent restenosis in T2D.

Clinical characteristics associated with high on-treatment platelet reactivity of patients undergoing PCI after a 300 mg loading dose of clopidogrel, measured by thrombelastography

BACKGROUND

Dual antiplatelet therapy with clopidogrel and aspirin is the standard of care for patients undergoing percutaneous coronary intervention (PCI).

OBJECTIVE

To determine the clinical characteristics associated with high on-treatment platelet reactivity (HPR) of patients undergoing PCI after a 300 mg loading dose of clopidogrel, measured by thrombelastography (TEG).

METHODS AND RESULTS

394 consecutive patients were enrolled in this prospective observational study. All had been receiving aspirin 100 mg/day for more than 7 days, but were clopidogrel naïve. A 300 mg loading dose of clopidogrel was given more than 12 h before the procedure. The cut-off point for HPR was defined as ≥70% adenosine-5-diphosphate-induced aggregation. The prevalence of HPR was 21% as measured by TEG. More women than men (41.7% vs 27.1%, p=0.01) were found in the HPR group. Raised glycosylated haemoglobin (HbA1c) was more prevalent in the HPR group than in the group with normal on-treatment platelet reactivity (NPR) (45.2% vs 30.0%, p=0.009). Patients with HPR had a higher level of total plasma cholesterol (4.8±1.5 mmol/l vs 4.3±1.1 mmol/l, p=0.002) and low-density lipoprotein cholesterol (2.8±1.1 mmol/l vs 2.5±0.9 mmol/l, p=0.022) than those with NPR. Multivariable logistic regression analysis showed that female gender (OR=3.175, 95% CI 1.428 to 7.059, p=0.005) and raised HbA1c (OR=1.911, 95% CI 1.066 to 3.428, p=0.03) independently predicted the occurrence of HPR.

CONCLUSIONS

Despite pretreatment with aspirin and a 300 mg loading dose of clopidogrel, 21% patients undergoing PCI exhibited HPR measured by TEG. A raised level of HbA1c and female gender independently predicted the findings.

[Metabolic syndrome as the risk factor for ischaemic stroke]

Metabolic syndrome (MetS) is a heterogeneous clinical entity represented by the occurrence of central obesity, hyperlipidaemia, hyperglycaemia and hypertension. The results of previous studies have shown that the probable common underlying pathophysiological factor for MetS is the insulin resistance phenomenon. However, the pathogenesis of the syndrome is still not well known. We present substantial information on MetS and the relationships between stroke and MetS as a compound entity, while individual components of MetS are well known risk factors for both first-in-life and recurrent ischaemic stroke. We also discuss primary and secondary stroke prevention in subjects with MetS.

The prothrombotic tendency in metabolic syndrome: focus on the potential mechanisms involved in impaired haemostasis and fibrinolytic balance

The metabolic syndrome is a clinical disorder characterized by impairment of glucose metabolism, increased arterial blood pressure, and abdominal obesity. The presence of these clinical features exposes patients to a high risk of atherothrombotic cardiovascular events. The pathogenesis of atherothrombosis in the metabolic syndrome is multifactorial, requiring a close relationship among the main components of the metabolic syndrome, including insulin resistance, alterations of glycaemic and lipid pattern, haemodynamic impairment, and early appearance of endothelial dysfunction. Furthermore, haemostatic alterations involving coagulation balance, fibrinolysis, and platelet function play a relevant role both in the progression of the arterial wall damage and in acute vascular events. The mechanisms linking abdominal obesity with prothrombotic changes in the metabolic syndrome have been identified and partially elucidated on the basis of alterations of each haemostatic variable and defined through the evidence of peculiar dysfunctions in the endocrine activity of adipose tissue responsible of vascular impairment, prothrombotic tendency, and low-grade chronic inflammation. This paper will focus on the direct role of adipose tissue on prothrombotic tendency in patients affected by metabolic syndrome, with adipocytes being able to produce and/or release cytokines and adipokines which deeply influence haemostatic/fibrinolytic balance, platelet function, and proinflammatory state.

The PPAR-Platelet Connection: Modulators of Inflammation and Potential Cardiovascular Effects

Historically, platelets were viewed as simple anucleate cells responsible for initiating thrombosis and maintaining hemostasis, but clearly they are also key mediators of inflammation and immune cell activation. An emerging body of evidence links platelet function and thrombosis to vascular inflammation. peroxisome proliferator-activated receptors (PPARs) play a major role in modulating inflammation and, interestingly, PPARs (PPARβ/δ and PPARγ) were recently identified in platelets. Additionally, PPAR agonists attenuate platelet activation; an important discovery for two reasons. First, activated platelets are formidable antagonists that initiate and prolong a cascade of events that contribute to cardiovascular disease (CVD) progression. Dampening platelet release of proinflammatory mediators, including CD40 ligand (CD40L, CD154), is essential to hinder this cascade. Second, understanding the biologic importance of platelet PPARs and the mechanism(s) by which PPARs regulate platelet activation will be imperative in designing therapeutic strategies lacking the deleterious or unwanted side effects of current treatment options.

Adipocytokines in atherothrombosis: focus on platelets and vascular smooth muscle cells

Visceral obesity is a relevant pathological condition closely associated with high risk of atherosclerotic vascular disease including myocardial infarction and stroke. The increased vascular risk is related also to peculiar dysfunction in the endocrine activity of adipose tissue responsible of vascular impairment (including endothelial dysfunction), prothrombotic tendency, and low-grade chronic inflammation. In particular, increased synthesis and release of different cytokines, including interleukins and tumor necrosis factor-α (TNF-α), and adipokines—such as leptin—have been reported as associated with future cardiovascular events. Since vascular cell dysfunction plays a major role in the atherothrombotic complications in central obesity, this paper aims at focusing, in particular, on the relationship between platelets and vascular smooth muscle cells, and the impaired secretory pattern of adipose tissue.

C-Peptide in the vessel wall

Patients with insulin resistance and early type 2 diabetes exhibit an increased sensitivity to develop a diffuse and extensive pattern of arteriosclerosis leading to a remarkable increase in vascular complications, including myocardial infarction and stroke. The accelerated atherosclerosis in these patients is likely to be multifactorial. In this review, we introduce the new hypothesis that C-peptide could play a role as a mediator of lesion development. Patients with type 2 diabetes show increased levels of the proinsulin cleavage product C-peptide, and in the past few years, various groups have examined the effect of C-peptide in vascular cells as well as its potential role in lesion development. Recent data suggest that C-peptide deposits in the vessel wall could promote the recruitment of monocytes and CD4-positive lymphocytes in early arteriosclerotic lesions. Furthermore, C-peptide induces proliferation of vascular smooth muscle cells, a critical step in atherogenesis and restenosis formation. The present review summarizes this new pathophysiological aspect and discusses the potential relevance for lesion development.

Contribution of insulin resistance to vascular dysfunction

Insulin is a vascular hormone, able to influence vascular cell responses. In this review, we consider the insulin actions on vascular endothelium and on vascular smooth muscle cells (VSMC) both in physiological conditions and in the presence of insulin resistance. In particular, we focus the relationships between activation of insulin signalling pathways of phosphatidylinositol-3 kinase (PI3-K) and mitogen-activated protein kinase (MAPK) and the different vascular actions of insulin, with a particular attention to the insulin ability to activate the pathway nitric oxide (NO)/cyclic GMP/PKG via PI3-K, owing to the peculiar relevance of NO in vascular biology. We also discuss the insulin actions mediated by the MAPK pathway (such as endothelin-1 synthesis and secretion and VSMC proliferation and migration) and by the interactions between the two pathways, both in insulin-sensitive and in insulin-resistant states. Finally, we consider the influence of free fatty acids, cytokines and endothelin on vascular insulin resistance.

Role of adipose tissue in haemostasis, coagulation and fibrinolysis

Obesity is associated with an increased incidence of insulin resistance (IR), type 2 diabetes mellitus and cardiovascular diseases. The increased risk for cardiovascular diseases could partly be caused by a prothrombotic state that exists because of abdominal obesity. Adipose tissue induces thrombocyte activation by the production of adipose tissue-derived hormones, often called adipokines, of which some such as leptin and adiponectin have been shown to directly interfere with platelet function. Increased adipose tissue mass induces IR and systemic low-grade inflammation, also affecting platelet function. It has been demonstrated that adipose tissue directly impairs fibrinolysis by the production of plasminogen activator inhibitor-1 and possibly thrombin-activatable fibrinolysis inhibitor. Adipose tissue may contribute to enhanced coagulation by direct tissue factor production, but hypercoagulability is likely to be primarily caused by affecting hepatic synthesis of the coagulation factors fibrinogen, factor VII, factor VIII and tissue factor, by releasing free fatty acids and pro-inflammatory cytokines (tumour necrosis factor-alpha, interleukin-1beta and interleukin-6) into the portal circulation and by inducing hepatic IR. Adipose tissue dysfunction could thus play a causal role in the prothrombotic state observed in obesity, by directly and indirectly affecting haemostasis, coagulation and fibrinolysis.

The effects of thiazolidinediones on blood pressure levels – A systematic review

Insulin resistance has been proposed to be the underlying disorder of the so-called metabolic or insulin resistance syndrome, which represents the clustering in the same individual of several cardiovascular risk factors, such as type 2 diabetes mellitus, hypertension, abdominal obesity, elevated triglycerides and low high-density lipoprotein-cholesterol. As far as the connection of insulin resistance and compensatory hyperinsulinaemia with hypertension is concerned, a number of mechanisms possibly linking these disturbances have been described, such as activation of sympathetic nervous system, enhancement of renal sodium reabsorption, or impairment of endothelium-dependent vasodilatation. Thiazolidinediones (TZDs) constitute a class of oral antihyperglycaemic agents that act by decreasing insulin resistance, and apart from their action on glycaemic control, they have been also reported to exert beneficial effects on other parameters of the metabolic syndrome. In particular, during recent years a considerable number of animal and human studies have shown that the use of TZDs was associated with usually small but significant reductions of blood pressure (BP) levels. Since a possible beneficial action of these compounds on BP could be of particular value for patients with the metabolic syndrome, this review aimed to summarize and evaluate the literature data in the field, derived either from studies that just examined BP levels among other parameters or from studies that were specifically designed to determine the effect of a TZD on BP.

Platelet dysfunction in central obesity

Central obesity is a relevant risk factor for major cardiovascular events due to the atherosclerotic involvement of coronary, cerebral and lower limb arterial vessels. A major role in the increased cardiovascular risk is played by platelets, which show an increased activation and a reduced sensitivity to the physiological and pharmacological antiaggregating agents. This review focuses on platelet dysfunction in central obesity. The mechanisms involved are related to: i) the reduced sensitivity to insulin and other substances acting via intracellular cyclic nucleotides, such as nitrates and prostacyclin; ii) the altered intracellular ionic milieu with elevated cytosolic Ca(2+); and iii) the increased oxidative stress, which elicits isoprostane production from arachidonic acid. Therapeutic guidelines recommend a multifactorial prevention of cardiovascular disease including antiplatelet drugs in high risk patients, even though, at present, the protective effect of antiplatelet therapy in obese, insulin resistant subjects has not been evaluated by specific trials. Some reports, however, suggest a decreased sensitivity to the antiaggregating effects of both acetylsalicylic acid (aspirin) and thienopyridines in human obesity. Platelet defects may play a pivotal role in the reduced efficacy of antiplatelet therapy in obese subjects in the setting of cardiovascular prevention and acute coronary syndrome treatment. Thus, a specifically tailored antiaggregating therapy is likely necessary in obese, insulin resistant subjects, especially in the presence of type 2 diabetes mellitus.

Atherogenesis and atherothrombosis--focus on diabetes mellitus

Diabetes mellitus represents a major cause of cardiovascular morbidity and mortality in developed countries, and atherothrombosis accounts for most deaths among patients with diabetes mellitus. Atherothrombosis is defined as atherosclerotic lesion disruption with superimposed thrombus formation. As a long-term, progressive disease process, atherosclerosis often results in an acute atherothrombotic event through plaque rupture and formation of a platelet-rich thrombus. The principal clinical manifestations of atherothrombosis are sudden cardiac death, myocardial infarction, ischaemic stroke, and peripheral arterial ischaemia comprising both intermittent claudication and critical limb ischaemia. Atherosclerosis is the leading cause of morbidity and mortality in the industrialized world, and diabetes mellitus magnifies the risk of cardiovascular events. In addition to the well-known microvascular complications of diabetes mellitus - such as nephropathy, retinopathy and neuropathy - the risk of macrovascular complications affecting the large conduit arteries markedly increases in patients with diabetes mellitus.

Diabetes mellitus: a prothrombotic state implications for outcomes after coronary revascularization

Coronary stent thrombosis is a serious problem in the drug-eluting stent era. Despite aggressive antiplatelet therapy during and after percutaneous coronary intervention (PCI), the incidence of sub-acute stent thrombosis remains approximately 0.5%–2%, which may represent a catastrophic clinical situation. Both procedural factors and discontinuation of antiplatelet therapy are normally associated with this event. We report on simultaneous stent thromboses of two drug-eluting stents implanted in two different vessels, which resulted in a life-threatening clinical condition. Possible contributing factors that led to synergistic thrombotic effects are discussed.

Biological mechanisms of stroke prevention by physical activity in type 2 diabetes

The principal modifiable risk factors for stroke are hypertension, diabetes mellitus, hypercholesterolaemia, hyperhomocysteinaemia, smoking and limited physical activity. However, it is not clear whether physical inactivity is a risk factor per se, or because it predisposes to pathological conditions that are risk factors for stroke. The limited availability of effective therapeutic approaches for stroke emphasizes the crucial role of prevention of risk factors. The global burden associated with type 2 diabetes is large and continues to grow. Convincing epidemiologic data support the role of physical activity in preventing type 2 diabetes. The increasing evidence of physical activity in preventing diabetic complications, including stroke, has generated interest in the molecular basis underlying these beneficial effects. The aim of the present review is to discuss the biological mechanisms underlying the effect of physical activity in preventing stroke in type 2 diabetes.

Effects of thiazolidinediones on blood pressure

Peroxisome-proliferator-activated receptor-gamma (PPAR-gamma) agonists (known as thiazolidinediones; TDZs) activate nuclear receptors that regulate gene expression; they were developed as insulin-sensitizing drugs to treat type 2 diabetes mellitus. Although the prototypic TZD troglitazone was withdrawn from the market due to hepatic toxicity, rosiglitazone and pioglitazone are mainstays in managing type 2 diabetes mellitus. TZDs exert their hypoglycemic effect by reducing insulin resistance, hence improving insulin sensitivity. However, TZDs also exhibit a broad range of cardiovascular actions, with the clinical consequence of reduction in blood pressure (BP), observed in animal models and human diabetic subjects. The magnitude of reduction appears to be about 4 to 5 mm Hg in systolic and 2 to 4 mm Hg in diastolic BP--sufficient to significantly reduce subsequent cardiovascular event rates. But these BP-reducing properties, which are not present with metformin or sulfonylureas, are particularly important when viewed in conjunction with hypoglycemic effects. A significant proportion of patients with type 2 diabetes mellitus and BP mildly above target range might be successfully treated for both processes with a single drug.

Platelet hyperaggregability: impaired responsiveness to nitric oxide ("platelet NO resistance") as a therapeutic target

Platelet hyperaggregability and associated thrombosis have been documented in a number of cardiovascular disease states. While one of the current mainstays of anti-thrombotic treatment (i.e. aspirin, clopidogrel, glycoprotein IIb/IIIa antagonists) has been directed at reducing platelet activation and aggregation, it is apparent that there are limitations to the effectiveness of these therapies. Nitric oxide (NO) plays an important role in platelet physiology. The ability of NO to regulate cyclic guanosine-3,'5'-monophosphate (cGMP), via activation of soluble guanylate cyclase, is the principal mechanism of negative control over platelet activity. NO is not only of the endothelial source, it is also released from activated platelets, providing a negative feedback. Studies in patients with symptomatic ischemia, chronic heart failure, diabetes and various risk factors for cardiovascular disease have demonstrated that platelets from these subjects exhibit reduced responsiveness to the anti-aggregating efficacy of NO: a phenomenon termed "platelet NO resistance". It constitutes an impaired physiological response to endogenous NO (endothelium-derived relaxing factor or EDRF), and as such may contribute to the increased risk of ischemic events. NO resistance also accounts for reduced pharmaco-activity of exogenous NO donors, e.g. organic nitrates. Platelet NO resistance results largely from a combination of "scavenging" of NO by superoxide anion radical and inactivation of soluble guanylate cyclase. NO resistance has both diagnostic and prognostic implications. The current review examines the association of platelet NO resistance with pathological hyperaggregability and discusses potential therapeutic strategies targeting this abnormality.

Diabetes mellitus as a prothrombotic condition

Diabetes mellitus (DM) is characterized by fasting hyperglycaemia and a high risk of atherothrombotic disorders affecting the coronary, cerebral and peripheral arterial trees. The risk of myocardial infarction (MI) is 3-5 fold higher in Type 2 DM and a DM subject with no history of MI has the same risk as a non-DM subject with a past history of MI. In total around 70% of deaths are vascular with poorer outcomes to both acute events and cardiological interventions. It was proposed that clustering of vascular risk factors (hyperinsulinaemia, dysglycaemia, dyslipidaemia and hypertension) around insulin resistance (IR) accounted for the increase in risk with Type 2 DM. The importance of this became apparent with the recognition that risk clustering occurs in normoglycaemic and impaired glucose tolerance (IGT) subjects with IR, in total around 25% of the population in addition to long-standing Type 1 subjects with renal disease. Evidence indicates that thrombotic risk clustering also occurs in association with IR, suppression of fibrinolysis due to elevated concentrations of the fibrinolytic inhibitor, plasminogen activator inhibitor-1 (PAI-1) is invariable with IR and there is evidence that this is regulated by the effects of triglyceride on the PAI-1 gene promoter. Other studies indicated that prothrombotic risk (coagulation factors VII, XII and fibrinogen) also associates with the IR syndrome. The development of endothelial cell dysfunction with suppression of nitric oxide and prostacyclin synthesis, combined with platelet resistance to the anti-aggregatory effects of these hormones leads to loss of control over platelet activation. In addition, hyperglycaemia and glycation have marked effects on fibrin structure function, generating a clot which has a denser structure, resistant to fibrinolysis. The combination of increased circulating coagulation zymogens, inhibition of fibrinolysis, changes in fibrin structure/function and alterations in platelet reactivity creates a thrombotic risk clustering which underpins the development of cardiovascular disease.

Impaired tissue responsiveness to organic nitrates and nitric oxide: a new therapeutic frontier?

Nitric oxide (NO) is a physiologically important modulator of both vasomotor tone and platelet aggregability. These effects of NO are predominantly mediated by cyclic guanosine-3,'5'-monophosphate (cGMP) via activation of soluble guanylate cyclase. However, in patients with ischemic heart disease, platelets and coronary/peripheral arteries are hyporesponsive to the antiaggregatory and vasodilator effects of NO donors. NO resistance is also associated with a number of coronary risk factors and presents in different disease states. It correlates with conventional measures of "endothelial dysfunction," and represents a multifaceted disorder, in which smooth muscle and platelet NO resistance are equally important, as sites of abnormal NO-driven physiology. NO resistance results largely from a combination of "scavenging" of NO by superoxide anion radical (O(2)(-)) and of (reversible) inactivation of soluble guanylate cyclase. It constitutes an impaired physiological response to endogenous NO (endothelium-derived relaxing factor, EDRF) and, as such, may contribute to the increased risk of ischemic events. Impairment in responsiveness to NO in ischemic patients implies a potential problem that those patients, in greatest need of nitrate therapy, may be least likely to respond. The prognostic impact of NO resistance at vascular and platelet levels has been demonstrated in patients with ischemic heart disease, and it has been shown that a number of agents (angiotensin-converting enzyme [ACE] inhibitors, perhexiline, insulin, and possibly statins) ameliorate this anomaly. The current review examines different aspects of the "NO resistance" phenomenon and discusses some related methodological issues.

Platelet resistance to the antiaggregatory cyclic nucleotides in central obesity involves reduced phosphorylation of vasodilator-stimulated phosphoprotein

BACKGROUND

Impairment of platelet response to antiaggregatory agents is seen in individuals with central obesity and may play a role in the increased cardiovascular risk associated with obesity. In this study we evaluated whether this impairment involves the antiaggregatory pathways regulated by cAMP and cGMP.

METHODS

We obtained platelet-rich plasma from 12 obese individuals and 12 controls. We investigated the effects of the cyclic nucleotide analogs 8-pCPT-cAMP (10-500 micromol/L) and 8-pCPT-cGMP (10-500 micromol/L) on ADP-induced platelet aggregation as assessed by decreased light scattering. We assessed the activation of cAMP- and cGMP-dependent protein kinases by measuring phosphorylation of the vasodilator-stimulated phosphoprotein (VASP) at Ser157 and Ser239.

RESULTS

The antiaggregatory effect of both cyclic nucleotide analogs was impaired in obese individuals compared to controls, with mean (SE) half-maximal inhibitory concentrations (IC(50)) (after 20-min incubation) of 123 (33) micromol/L vs 5 (1) micromol/L, respectively, for 8-pCPT-cAMP (P <0.01) and of 172 (43) micromol/L vs 17 (8) micromol/L, respectively, for 8-pCPT-cGMP (P <0.01). The Homeostasis Model Assessment Index of Insulin Resistance was independently correlated with cyclic nucleotide analog IC(50). In obese individuals, VASP phosphorylation at Ser157 and Ser239 in response to cyclic nucleotides was significantly lower than in controls.

CONCLUSIONS

In central obesity the reduced ability of cyclic nucleotides to inhibit platelet aggregation is associated with reduced activation of their specific kinases. Because cyclic nucleotides help regulate platelet antiaggregation, alteration of this ability is consistent with platelet hyperactivity in obesity.

The deleterious effects of hyperglycemia on platelet function in diabetic patients with acute coronary syndromes mediation by superoxide production, resolution with intensive insulin administration

OBJECTIVES

This study sought to assess the determinants of platelet nitric oxide (NO) responsiveness in diabetic patients admitted with acute coronary syndromes (ACS) and the short-term effects of aggressive glycemic control on these factors.

BACKGROUND

Hyperglycemia is an independent risk factor for mortality in both diabetic patients and nondiabetic patients with ACS. The mechanism(s) underlying this observation and potential benefit from its correction remain uncertain. Although a reduction in NO bioavailability has been proposed, this remains untested in the ACS setting.

METHODS

A total of 76 diabetic patients with ACS were studied. Putative correlations between admission blood sugar level (BSL), inhibition of platelet aggregation by the NO donor sodium nitroprusside (SNP), and superoxide (O2-) were assessed. Hyperglycemic patients (n = 60) were randomized to acute glycemic control with intravenous versus subcutaneous insulin, and changes in the aforementioned parameters were compared. Plasma levels of the endogenous inhibitor of NO synthase asymmetric dimethylarginine (ADMA) were also monitored.

RESULTS

There was an inverse correlation between admission BSL and both platelet SNP response (p = 0.007) and ADMA levels (p = 0.045), and a positive correlation with O2- generation (p < 0.001). Intravenous insulin infusion resulted in a greater reduction (p < 0.001) in BSL, differentially improved platelet responsiveness to SNP (p = 0.049), and decreased O2- (p < 0.001) and ADMA levels (p = 0.049).

CONCLUSIONS

A component of platelet dysfunction in diabetic patients with ACS is impaired responsiveness to the anti-aggregatory effects of NO, probably reflecting increased NO clearance by O2-. This phenomenon is reversed by acute aggressive glycemic control. These findings provide a further rationale for use of insulin therapy in acute myocardial infarction and suggest its extension to ACS patients.

Insulin Resistance as a Determinant of Platelet Activation in Obese Women

OBJECTIVES

We tested the hypothesis that insulin resistance, per se, contributes to increased platelet activation in obesity, independently of underlying inflammation.

BACKGROUND

Obesity, insulin resistance, and atherosclerosis are closely linked phenomena associated with low-grade inflammation. Obesity is associated with persistent platelet activation in otherwise healthy women.

METHODS

We performed a cross-sectional study in 40 obese and 20 non-obese healthy women using urinary thromboxane metabolite excretion as a non-invasive index of platelet activation. An index of insulin sensitivity, S(I), and plasma adiponectin, C-reactive protein (CRP), and CD40 ligand (CD40L) levels were measured.

RESULTS

Obese women had significantly (p < 0.0001) higher 11-dehydro-thromboxane B2 (11-dehydro-TXB2) excretion (median 718 vs. 211 pg/mg creatinine), CRP (1.13 vs. 0.48 mg/l), and CD40L levels (4.45 vs. 0.90 ng/ml) than controls. Obese women had lower S(I) (median 2.51 vs. 5.0 10(4) min(-1)/[microU/ml], p < 0.002) and adiponectin (6.3 vs. 10 microg/ml, p < 0.01) than control subjects. On multiple regression analysis, waist-to-hip ratio (beta = 0.27, p < 0.05) and S(I) (beta = -0.72, p < 0.04) predicted 11-dehydro-TXB2 excretion rate, independently of adiponectin, CRP, CD40L, and lipid patterns. In order to investigate the cause-effect relationship of these associations, we examined the effects of a 12-week weight loss program or a 3-week pioglitazone treatment on urinary 11-dehydro-TXB2 in 10 women with impaired S(I) and visceral obesity. Successful weight loss (0.6 kg loss/week) achieved in 5 subjects was associated with increased S(I) (+92%) and decreased CD40L (-27%), CRP (-37%), and 11-dehydro-TXB2 (-53%) (p < 0.05). Consistently, improvement of insulin sensitivity achieved with pioglitazone significantly decreased urinary 11-dehydro-TXB2 excretion (-43%, p < 0.05) without changes in body weight.

CONCLUSIONS

Insulin resistance is a major determinant of platelet activation in female obesity.

Platelet activation is associated with hypoadiponectinemia and carotid atherosclerosis

Adiponectin, an adipokine secreted specifically from adipose tissue, has plurifunctions including antidiabetic, antiatherosclerotic, and antiinflammatory functions. Recently, platelet activation and the subsequent local inflammation have been implicated in progression of atherosclerosis. The aim of the study is to examine the interrelation among plasma adiponectin levels, platelet activation status and quantitatively determined carotid atherosclerosis. Subjects (n = 277) including 136 type 2 diabetic, 138 hypertensive, and 203 hypercholesterolemic patients participated in the study. Platelet activation was determined as percentage of polymorphonuclear cells (PMNs) or monocytes aggregated with platelets analyzed by CD41-positivity determined by whole-blood flow cytometry. PMN-platelet aggregates were significantly and positively associated with carotid atherosclerosis (intimal-medial thickness, IMT) with the interaction stronger than that of monocyte-platelet aggregates. Stepwise regression analyses revealed that PMN-platelet aggregates were the third strongest determinant of carotid IMT, with age and HbA1c stronger independent determinants. Simple and stepwise regression analyses of the factors associated with PMN-platelet aggregates revealed that HbA1c (r = 0.423), serum adiponectin levels (r = -0.289) and age (r = -0.184) were the three independent determinants. Thus, our data unveil novel link between hypoadiponectinemia and platelet activation.

Coagulation and atherothrombotic disease

Atherothrombotic disease arises secondary to a complex gene-environment interaction. In the initial stages, the condition is clinically silent but with more advanced disease, an occlusive thrombus is formed resulting in the classical clinical manifestations. Both environmental factors and genetic variations in elements of the clotting cascade influence thrombosis risk by inducing quantitative and qualitative changes in the mature protein, which may affect the final structure of the clot and determine its resistance to lysis. Understanding the fine details of gene-environment interactions in relation to thrombus formation will help to shed more light on disease pathogenesis. Consequently, this will allow the development of more efficacious treatment strategies and will also help to identify subjects at risk, thereby enabling the introduction of early preventative measures.

Clustering of insulin resistance with vascular dysfunction and low-grade inflammation in type 2 diabetes

Vascular dysfunction, low-grade inflammation, insulin resistance, and impaired fibrinolysis have each been reported to be present in type 2 diabetes, but their relationships, and the role of obesity, have not been investigated. We measured insulin sensitivity (euglycemic clamp), forearm blood flow responses to graded local acetylcholine (Ach) and sodium nitroprusside (SNP) infusions, plasma concentrations of tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, von Willebrand factor (vWF), plasminogen activator inhibitor (PAI)-1, tissue plasminogen activator (tPA), and high-sensitivity C-reactive protein (hs-CRP) in 81 diabetic patients. When patients were stratified by insulin resistance, more severe insulin resistance was associated (P < 0.05) with overweight, central fat distribution, hypertension, and dyslipidemia (with similar sex distribution, age, fasting plasma glucose, and HbA1c). With regard to vascular function, both endothelium-dependent (Ach) (-22, -40, and -52%; P < 0.0001) and -independent (SNP) (-3, -7, and -27%; P < 0.02) vasodilatation were progressively reduced across insulin resistance tertiles. In multivariate analysis, inflammatory markers (IL-6, hs-CRP, and TNF-alpha) were independently associated with insulin resistance and fasting glycemia, fibrinolytic markers PAI-1 and tPA with insulin resistance and central fat distribution, and vascular indexes (vWF, Ach, and SNP vasodilation) with insulin resistance and obesity or cytokines (TNF-alpha or IL-6). In type 2 diabetes, insulin resistance is associated with vascular dysfunction/damage, impaired fibrinolysis, and low-grade inflammation independently of obesity and poor glycemic control.