PPAR agonists in the treatment of insulin resistance and associated arterial disease

Augmented release of non-esterified fatty acids (NEFA) from insulin-resistant adipocytes appears to be the main cause of the 'atherogenic lipoprotein profile' associated with insulin resistance and type 2 diabetes. This atherogenic profile is characterised by large very-low-density lipoproteins (VLDL), small, dense low-density lipoproteins (LDL) and low levels of high-density lipoproteins (HDL), resulting in deposition of apo B lipoproteins in the vascular intima and subsequent inhibition of reverse cholesterol transport. This lipoprotein retention also results in a proinflammatory response from the vascular endothelium, which is increased in insulin resistance. Thus the ideal therapy for insulin resistance, and its complications, should both improve its associated dyslipidaemia and ameliorate the vascular atherogenic reaction. Some peroxisome proliferator-activated receptor (PPAR)-gamma and dual PPARalpha/gamma agonists improve insulin resistance and its dyslipidaemia, both in rodents and man, while in animal models they can show clear antiatherosclerotic effects. Nonetheless, it is difficult to evaluate how much of these antiatherosclerotic actions are caused by effects on the dyslipidaemia or by direct effects on vascular cells. Upregulation of PPARgamma and PPARalpha/gamma activity in macrophages can reduce secretion of proinflammatory cytokines and matrix metalloproteases, as well as increase HDL-mediated cholesterol efflux transport--all potentially antiatherosclerotic results. In addition, treatment of smooth muscle cells with PPARgamma agonists can partially revert possible atherogenic changes in the production of matrix proteoglycans induced by exposure to NEFA. Although these findings are still preliminary, and their relevance to human atherosclerosis has not been fully elaborated, these results suggest that improved PPARalpha/gamma agonism may positively modulate several of the metabolic steps connecting insulin resistance with dyslipidaemia and with the atherogenic response.

The relationship of obesity to the metabolic syndrome

Obese patients with the metabolic syndrome generally have a visceral (apple-shaped) fat distribution and are at an increased risk of macrovascular disease, while those with peripheral (pear-shaped) obesity tend not to have metabolic abnormalities and are at less risk. This difference appears to be related to the differing metabolic functions (and secretory products) of visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT), as well as the fact that VAT drains directly into the liver. Thus, it appears that increased VAT, but not SAT, is associated with both hepatic and peripheral biochemical abnormalities leading to insulin resistance and the associated metabolic syndrome. Insulin resistance is associated with VAT products, such as free fatty acids and their metabolites, as well as cytokines, such as tumour necrosis factor alpha (TNF-alpha). These factors may activate components of the inflammatory pathway such as nuclear factor kappa-B (NFkappaB), and inhibit insulin signalling. Insulin resistance is further associated with decreased levels of another tissue product, adiponectin. The incidence and prevalence of obesity is increasing at an unprecedented rate. The classic treatment of obesity is weight loss via lifestyle modification. However, prevention of obesity comorbidity can also be achieved by modifying the mechanisms by which obesity causes these comorbid conditions. For instance, it is now known that the peroxisome proliferator-activated receptor (PPAR) family of transcriptional regulators are crucial in regulating adipose tissue development and metabolism; this helps explain why compounds with PPARgamma agonist activity, e.g. thiazolidinediones, increase insulin action through their effects in regulating adipose tissue metabolism.

Determinants of plasminogen activator inhibitor-1 in South Asians with ischaemic stroke

To investigate the relationship of circulating plasminogen activator inhibitor-1 (PAI-1) levels with features of insulin resistance and genotype at a single nucleotide insertion/deletion (4G/5G) polymorphism in the promoter region of the PAI-1 gene in 101 South Asian ischaemic stroke patients and 102 symptom-free reference subjects. The allele frequencies were 4G-0.51, 5G-0.49 and 4G-0.61, 5G-0.39 in patients and reference subjects, respectively. There was a significant association between PAI-1 promoter genotype and PAI-1 antigen levels in patients. Regression analysis with significant correlates in the model demonstrated age, gender and triglycerides in patients and fasting insulin and HDL cholesterol in reference subjects as independent predictors of PAI-1 antigen.

Pocket tape measure for waist circumference: training medical students and residents on a simple assessment of body composition

Metabolic syndrome, the clustering of hyperglycemia, hypertension and dyslipidemia, increases the risk of coronary heart disease. Abdominal obesity is an important cue for the clinician to consider metabolic syndrome. Measurement of waist circumference is a simple means of identifying abdominal obesity. The development and distribution of pocket tape measures to medical students, residents and attending physicians were initiated to enhance identification and treatment of metabolic syndrome. Distribution of the tape measures was added to a cardiovascular nutrition component in a 4th-y medical school curriculum. The nutrition component continued to include computer-based cases and pocket reference cards. Limited data suggest that the addition of pocket tape measures to the nutrition component of an ambulatory care clerkship may increase the percentage of medical students who use waist circumference to identify patients at risk for metabolic syndrome. It is anticipated that student use will increase with role modeling by residents and attending physicians.

Researchers sound the alarm on risks associated with metabolic syndrome

As much as one-third of the population has it, and the condition has been strongly linked with CVD, diabetes, and early death. But currently very little is being done to identify or treat this dangerous cluster of conditions. If there is good news, it is that relatively simple interventions can substantially improve a person's risk profile. Get the details.

Association of albuminuria and the metabolic syndrome

Microalbuminuria clusters with the metabolic syndrome, and both conditions predict cardiovascular disease mortality. The reported relationships of microalbuminuria with the individual components of the metabolic syndrome (i.e., hyperglycemia, insulin resistance, hypertension, dyslipidemia, abdominal obesity) are variable. Each of these components, as well as intrauterine effects and diet and other lifestyle factors, may contribute to elevated risk of microalbuminuria in certain population groups. Recent evidence indicates a role for oxidation and inflammation in cardiovascular disease, and endothelial dysfunction (exacerbated by factors such as dyslipidemia) may be the mediator of this relationship. Because endothelial dysfunction can also be manifested as microalbuminuria, this provides a potential explanation of the observed association of the metabolic syndrome, chronic inflammation, and microalbuminuria.

Weight loss and weight maintenance, ambulatory blood pressure and cardiac autonomic tone in obese persons with the metabolic syndrome

BACKGROUND

Cardiac autonomic function may play a role in obesity-associated hypertension. Most studies on the effects of weight loss on blood pressure and autonomic function do not distinguish between acute or continuing weight loss and steady-state weight maintenance after weight loss.

OBJECTIVES

We sought to clarify the changes in ambulatory blood pressure, heart rate and heart rate variability as assessed by spectral analysis during rapid weight loss and extended weight maintenance.

PARTICIPANTS

Abdominally obese (body mass index 35.2 +/- 2.1 kg/m2, waist 114.3 +/- 9.0 cm) men and women (n = 41) with the metabolic syndrome.

METHODS AND RESULTS

The 34 men and women completing the 1-year weight maintenance period lost 14.6 +/- 3.5 kg during the 9-week very-low-calorie diet and maintained a 12.5 +/- 7.5 kg weight loss to the end of the trial. Ambulatory 24-h blood pressure decreased dramatically during the diet (-9.0 +/- 8.0/-4.6 +/- 4.9 mmHg), but had risen to near baseline levels by the end of weight maintenance (-2.2 +/- 8.2 /-1.2 +/- 6.1 mmHg). Night-time heart rate decreased (-5.5 +/- 9.6 beats/min, P = 0.012), and heart rate variability total and low-frequency power measured during 5 min of controlled breathing increased by 46-56% (P = 0.003-0.09) during rapid weight loss. These changes gradually attenuated during weight maintenance, and only the change in night-time heart rate was still of borderline significance after 1 year of weight maintenance (-3.6 +/- 8.6 beats/min, P = 0.063). Heart rate variability high-frequency power tended to increase during weight loss and weight maintenance.

CONCLUSION

Despite successful weight maintenance, the decrease in ambulatory blood pressure after rapid weight loss was largely transient. The increase in parasympathetic tone was more sustained, but also gradually attenuated during 1 year of weight maintenance.

Epidemiology of the insulin resistance syndrome

The insulin resistance syndrome consists of the co-occurrence of metabolic risk factors for type 2 diabetes and cardiovascular disease, including overall obesity, central obesity, dyslipidemia (characterized by elevated levels of triglycerides and low levels of high-density lipoprotein cholesterol), hyperglycemia, and hypertension. Using criteria proposed by the National Cholesterol Education Program Adult Treatment Panel III, national survey data suggest the insulin resistance syndrome is very common, affecting about 24% of US adults aged greater than 20 years. The syndrome is more common in older people and in Mexican Americans, and will increase in prevalence as populations age and become more obese. Identification of the syndrome warrants aggressive interventions known to prevent type 2 diabetes and cardiovascular disease, including weight reduction, increased physical activity, and control of hypertension and dyslipidemia.

Lipid abnormalities in the metabolic syndrome

The metabolic syndrome is the constellation of adverse metabolic and clinical effects of insulin resistance. Its high and increasing prevalence and its profound impact on the major diseases of the western world require that clinicians consider its diagnosis and management on a routine basis. Recently published guidelines on its definition now make convenient and reliable diagnosis possible. Also, there is new and better understanding of the complex dyslipidemias and other risk factors strongly associated with the metabolic syndrome, which greatly increase the risk of clinical atherosclerotic events. Comprehensive clinical evaluation of these dyslipidemias and associated atherosclerosis risk factors can lead to their aggressive treatment, customized according to the circumstances of each patient. These steps are now more feasible and more clearly desirable than ever before. Statins alone greatly reduce atherosclerosis risk, but combination lipid therapy is often required for optimal dyslipidemia management and atheroprevention.

Endothelial dysfunction and the metabolic syndrome

The metabolic syndrome is a highly prevalent multifaceted clinical entity produced through the interaction of genetic, hormonal, and lifestyle factors. A distinctive constellation of abnormalities precedes and predicts the accelerated development of inflammation and coagulation represent emerging risk contributors associated with obesity and insulin resistance, central components of the metabolic syndrome, which act in concert with traditional abnormalities to increase cardiovascular risk. The initiation and progression of atherosclerosis may have its origins in impaired endothelial function that can be detected at the earliest stages of development of the syndrome. The basic elements of the metabolic syndrome and accelerated phase of atherogenesis are often silent partners that present many years before the onset of type 2 diabetes mellitus. The ability to detect and monitor subclinical vascular disease, as a reflection of the multiple factors that contribute to impair arterial wall integrity, holds potential to further refine cardiovascular risk stratification. Noninvasive assessment of vascular health may also aid the clinical decision-making process by guiding therapeutic interventions to optimize vascular protection in the metabolic syndrome.

Association of hyperglycemia and insulin with diabetic cardiovascular complications

Patients with diabetes and/or insulin resistance syndrome are at increased risk for developing cardiovascular disease. The UKPDS raised a great debate about the relative importance of hyperglycemia in the development of cardiovascular disease. Recently, several epidemiologic studies have suggested that high postprandial blood glucose levels are associated with a significant risk for the development of cardiovascular disease well as a grave prognosis for these patients during acute coronary events. In addition, a number of reports reinforce the thesis that postprandial hyperglycemia is a risk factor for mortality. Our review summarizes the current knowledge on the relation between blood glucose, insulin levels, and cardiovascular morbidity and mortality, relating these data to the new World Health Organization and American Diabetes Association classification of disturbed glucose metabolism.

C-reactive protein, the metabolic syndrome, and risk of incident cardiovascular events: an 8-year follow-up of 14 719 initially healthy American women

BACKGROUND

The metabolic syndrome describes a high-risk population having 3 or more of the following clinical characteristics: upper-body obesity, hypertriglyceridemia, low HDL, hypertension, and abnormal glucose. All of these attributes, however, are associated with increased levels of C-reactive protein (CRP).

METHODS AND RESULTS

We evaluated interrelationships between CRP, the metabolic syndrome, and incident cardiovascular events among 14 719 apparently healthy women who were followed up for an 8-year period for myocardial infarction, stroke, coronary revascularization, or cardiovascular death; 24% of the cohort had the metabolic syndrome at study entry. At baseline, median CRP levels for those with 0, 1, 2, 3, 4, or 5 characteristics of the metabolic syndrome were 0.68, 1.09, 1.93, 3.01, 3.88, and 5.75 mg/L, respectively (P(trend) <0.0001). Over the 8-year follow-up, cardiovascular event-free survival rates based on CRP levels above or below 3.0 mg/L were similar to survival rates based on having 3 or more characteristics of the metabolic syndrome. At all levels of severity of the metabolic syndrome, however, CRP added prognostic information on subsequent risk. For example, among those with the metabolic syndrome at study entry, age-adjusted incidence rates of future cardiovascular events were 3.4 and 5.9 per 1000 person-years of exposure for those with baseline CRP levels less than or greater than 3.0 mg/L, respectively. Additive effects for CRP were also observed for those with 4 or 5 characteristics of the metabolic syndrome. The use of different definitions of the metabolic syndrome had minimal impact on these findings.

CONCLUSIONS

These prospective data suggest that measurement of CRP adds clinically important prognostic information to the metabolic syndrome.

Does Homocysteine Cause Hypertension?

Several studies, some population-based, have plasma homocysteine levels linked to blood pressure, especially systolic pressure. In one large and carefully conducted epidemiological study, each 5 micromol/l increase in plasma homocysteine was associated with an increase in systolic and diastolic blood pressure of 0.7/0.5 mmHg in men and 1.2/0.7 mmHg in women, which was independent of renal function and B vitamin status. In addition, observations that homocysteine-lowering therapies with folic acid-based treatments have been followed by decreases in blood pressure raise the possibility that the link between homocysteine and blood pressure is causal, which is important since homocysteine levels can easily be lowered by folic acid-based regimens. Mechanisms that could explain the relationship between homocysteine and blood pressure include homocysteine-induced arteriolar constriction, renal dysfunction and increased sodium reabsorption, and increased arterial stiffness. However, there is only circumstantial evidence that these mechanisms are operative in humans. In addition, confounding by subtle renal dysfunction or by unmeasured dietary and lifestyle factors cannot be excluded as an explanation for the association between homocysteine and blood pressure. At present, therefore, the hypothesis that homocysteine increases blood pressure must be considered unproven. Ongoing large intervention studies with homocysteine-lowering vitamins may show whether blood pressure is indeed lowered by these vitamins, whether the blood pressure decrease, if any, is explained by the decrease in homocysteine levels, and whether a vitamin treatment-associated decrease in cardiovascular morbidity, if any, is explained by the decrease in blood pressure.

Hypertension in obese patients: a dysmetabolic hypertension with a possible adipocyte dysfunction mechanism

Large longitudinal studies showed the epidemiological link between obesity and hypertension. During last years, multiple possible mechanisms involved in this association were identified. Adipose tissue has an important role in the genesis of hypertension in obese patients through several pathways: insulin resistance, leptin, renin-angiotensin-aldosteron system and mediators of inflammation (TNF-alpha, IL-6). Adipocyte may be the major player in the development of insulin resistance and hypertension, elements of the metabolic syndrome, responsible for the cardiovascular complications.

Microcirculation: target therapy in cardiovascular diseases - a clinical perspective

Microcirculation conduit, distribution, exchange and reception vessels usually retain a demand-dependent vascular-tissue match as well as a nutrient friendly capillary-matrix tissue match. Various stimuli can initiate a vascular-capillary matrix-tissue mismatch. Counter-regulatory mechanisms result in hyperplasia or apoptosis. Microvascular disease (MVD) as a consequence or outcome of supply-demand mismatch has clinical therapeutic and prognostic implications in the hypertensive syndrome and coronary artery disease (CAD) cases. Recognition of the role of apoptosis and MVD may initiate a paradigm shift in clinical practice. Digitalis and other anti-hypertensive agents have anti-apoptotic action and MVD blunting effects that can control LVH development to reduce congestive heart failure (CHF) progression.

Insulin therapy for reducing cardiovascular risk in patients with type 2 diabetes

Twenty-four percent of the adult American population have the metabolic syndrome. Although somewhat counterintuitive, carefully regulated treatment with insulin has been shown to reduce insulin resistance and may also retard the development of cardiovascular disease by preventing chronic hyperglycemia, a condition that synergistically contributes to many proatherogenic pathways, including glycoxidation, the polyol pathway, advanced glycation end products, interference with normal metabolic pathways, and stimulation of protein kinase C-beta and proinflammatory pathways. This article describes some of the physiologic changes that occur when hyperglycemia and insulin resistance develop in patients with type 2 diabetes and discusses therapies, including insulin, that normalize glucose and reduce insulin resistance, thereby potentially reducing cardiovascular risk.

Microvascular disease relevance in the hypertension syndrome

Hypertension is not an isolated problem. Co-morbidities of smoking, obesity, diabetes and dyslipidemia are all associated with microvascular disease (MVD) with abnormal PET scan and endothelial dysfunction. MVD may contribute to left ventricular hypertrophy (LVH) via an imbalance between hyperplasia and apoptotic signals. Digitalis and other anti-hypertensive agents have anti-apoptotic action and MVD blunting effects, respectively. Heart failure progression must then be based on the preservation of myocyte integrity. Indeed, altered contractility appears to be a consequence of rather than the cause of myocyte deterioration. LV systolic dysfunction improvement is already a late strategy. Furthermore, the efficacy of anti-hypertension therapy may be limited in restoring LV diastolic function. Recognition of the role of apoptosis and MVD may initiate a paradigm shift in clinical practice.

The metabolic syndrome and total and cardiovascular disease mortality in middle-aged men

CONTEXT

The metabolic syndrome, a concurrence of disturbed glucose and insulin metabolism, overweight and abdominal fat distribution, mild dyslipidemia, and hypertension, is associated with subsequent development of type 2 diabetes mellitus and cardiovascular disease (CVD). Despite its high prevalence, little is known of the prospective association of the metabolic syndrome with cardiovascular and overall mortality.

OBJECTIVE

To assess the association of the metabolic syndrome with cardiovascular and overall mortality using recently proposed definitions and factor analysis.

DESIGN, SETTING, AND PARTICIPANTS

The Kuopio Ischaemic Heart Disease Risk Factor Study, a population-based, prospective cohort study of 1209 Finnish men aged 42 to 60 years at baseline (1984-1989) who were initially without CVD, cancer, or diabetes. Follow-up continued through December 1998.

MAIN OUTCOME MEASURES

Death due to coronary heart disease (CHD), CVD, and any cause among men with vs without the metabolic syndrome, using 4 definitions based on the National Cholesterol Education Program (NCEP) and the World Health Organization (WHO).

RESULTS

The prevalence of the metabolic syndrome ranged from 8.8% to 14.3%, depending on the definition. There were 109 deaths during the approximately 11.4-year follow-up, of which 46 and 27 were due to CVD and CHD, respectively. Men with the metabolic syndrome as defined by the NCEP were 2.9 (95% confidence interval [CI], 1.2-7.2) to 4.2 (95% CI, 1.6-10.8) times more likely and, as defined by the WHO, 2.9 (95% CI, 1.2-6.8) to 3.3 (95% CI, 1.4-7.7) times more likely to die of CHD after adjustment for conventional cardiovascular risk factors. The metabolic syndrome as defined by the WHO was associated with 2.6 (95% CI, 1.4-5.1) to 3.0 (95% CI, 1.5-5.7) times higher CVD mortality and 1.9 (95% CI, 1.2-3.0) to 2.1 (95% CI, 1.3-3.3) times higher all-cause mortality. The NCEP definition less consistently predicted CVD and all-cause mortality. Factor analysis using 13 variables associated with metabolic or cardiovascular risk yielded a metabolic syndrome factor that explained 18% of total variance. Men with loadings on the metabolic factor in the highest quarter were 3.6 (95% CI, 1.7-7.9), 3.2 (95% CI, 1.7-5.8), and 2.3 (95% CI, 1.5-3.4) times more likely to die of CHD, CVD, and any cause, respectively.

CONCLUSIONS

Cardiovascular disease and all-cause mortality are increased in men with the metabolic syndrome, even in the absence of baseline CVD and diabetes. Early identification, treatment, and prevention of the metabolic syndrome present a major challenge for health care professionals facing an epidemic of overweight and sedentary lifestyle.

The metabolic syndrome: psychopharmacologists should weigh the evidence for weighing the patient

We are in the midst of a North American epidemic of obesity and type 2 diabetes. Since patients with psychiatric disorders who receive psychopharmacologic treatments may be at even greater risk than the general population for weight gain, dyslipidemia, and diabetes and their complications, psychopharmacologists now need standards for how to monitor and manage these risks.

Asymmetric dimethylarginine (ADMA): a potential link between endothelial dysfunction and cardiovascular diseases in insulin resistance syndrome?

Endothelium-derived nitric oxide plays a major role in the regulation of vascular tone and in the maintenance of vascular homeostasis. Endothelial dysfunction with impaired nitric oxide biosynthesis and decreased bioavailability has been implicated in insulin resistance syndrome and Type II (non-insulin-dependent) diabetes mellitus. Nitric oxide is synthesised by nitric oxide synthase. Asymmetric dimethylarginine is a major endogenous nitric oxide synthase inhibitor. Increased circulating asymmetric dimethylarginine was initially found in patients with chronic renal failure and subsequently many other disease states. Increased asymmetric dimethylarginine plasma concentrations could contribute to the development of insulin resistance and coronary heart disease. Understanding of the pathophysiological role of asymmetric dimethylarginine could lead to novel therapies in the prevention of arteriosclerosis and coronary heart disease.

Low serum magnesium levels and metabolic syndrome

Low serum magnesium levels are related to diabetes mellitus (DM) and high blood pressure (HBP), but as far as we know, there are no previous reports that analyzed the serum magnesium concentration in individuals with metabolic syndrome (MS). We performed a cross-sectional population-based study to compare 192 individuals with MS and 384 disorder-free control subjects, matched by age and gender. Magnesium supplementation treatment and conditions likely to provoke hypomagnesemia, including previous diagnosis of diabetes mellitus (DM) and/or high blood pressure (HBP), were exclusion criteria. In this regard, only incident cases of DM and HBP were included. MS was defined by the presence at least of two of the following features: hyperglycemia (> or =7.0 mmol/l); HBP (> or =160/90 mmHg); dyslipidemia (fasting triglycerides > or =1.7 mmol/l and/or HDL-cholesterol <1.0 mmol/l); and obesity (body mass index > or =30 kg/m(2) and/or waist-to-hip ratio > or =0.85 in women or > or =0.9 in men). Low serum magnesium levels were identified in 126 (65.6%) and 19 (4.9%) individuals with and without MS, p<0.00001. The mean serum magnesium level among subjects with MS was 1.8+/-0.3 mg/dl, and among control subjects 2.2+/-0.2 mg/dl, p<0.00001. There was a strong independent relationship between low serum magnesium levels and MS (odds ratio (OR)=6.8, CI(95%) 4.2-10.9). Among the components of MS, dyslipidemia (OR 2.8, CI(95%) 1.3-2.9) and HBP (OR 1.9, CI(95%) 1.4-2.8) were strongly related to low serum magnesium levels. This study reveals a strong relationship between decreased serum magnesium and MS.

Metabolic syndrome and development of diabetes mellitus: application and validation of recently suggested definitions of the metabolic syndrome in a prospective cohort study

The World Health Organization (WHO) and the National Cholesterol Education Program (NCEP) recently proposed definitions for the metabolic syndrome. Little is known of their validity, however. The authors assessed the sensitivity and specificity of the definitions of the metabolic syndrome for prevalent and incident diabetes mellitus in a Finnish population-based cohort of middle-aged men (n = 1,005) followed for 4 years since the late 1980s. Four definitions based on the WHO and NCEP recommendations were compared. All definitions identified persons at high risk for developing diabetes during the 4-year follow-up (odds ratios = 5.0-8.8). The WHO definition including waist-hip ratio > 0.90 or body mass index >or= 30 kg/m(2) was the most sensitive (0.83 and 0.67) and least specific (0.78 and 0.80) in detecting the 47 prevalent and 51 incident cases of diabetes. The NCEP definition in which adiposity was defined as waist girth > 102 cm detected only 61% of prevalent and 41% of incident diabetes, although it was the most specific (0.89 and 0.90). The WHO definition seems valid as judged by its relatively high sensitivity and specificity in predicting diabetes. The NCEP definition including waist > 102 cm also identifies persons at high risk for diabetes, but it is relatively insensitive in predicting diabetes.

[Metabolic aspects of the polycystic ovary syndrome]

The author reviews the history of the term polycystic ovaries syndrome. He emphasizes the importance of insulin resistance in this disease. According to more recent criteria for the definition of the syndrome suffices the finding of hyperandrogenism, an irregular cycle (after elimination of other classical causes of this condition) and insulin resistance. The frequency of the disease varies in different populations up to 10%. It is significantly associated in particular with type 2 diabetes and obesity. The molecular biology of the syndrome is obscure. The metabolic syndrome as well as the polycystic ovaries syndrome have partly a genetic pathogenesis as well as an environmentally induced participation caused by stress. The polycystic ovaries syndrome is nowadays unequivocally an atherogenic syndrome and is a unit very close to Reaven's metabolic syndrome X or is part of this syndrome.

The metabolic syndrome, type 2 diabetes, and cardiovascular disease: understanding the role of insulin resistance

The most common and clinically important complication in adults with diabetes is cardiovascular disease (CVD), which includes coronary heart disease, peripheral vascular disease, and stroke. Both type 2 diabetes and the insulin resistance syndrome are associated with a marked increase in the risk for CVD. The metabolic syndrome and the closely related insulin resistance syndrome have recently been recognized as important disorders, each being associated with an increase in CVD risk even in the absence of glucose intolerance. Given the significant public health burden of CVD, risk reduction has emerged as a significant clinical challenge for most practitioners. Diabetes and the insulin resistance syndrome are closely related disorders, with insulin resistance being more than a key pathogenic defect in type 2 diabetes. Even in the absence of glucose intolerance, these 2 disorders are both associated with a number of distinct pathologic findings, including hypertension, atherogenic dyslipidemia, a prothrombotic environment, and significant vascular and hemodynamic abnormalities that result from endothelial cell dysfunction. Insulin resistance is now recognized to be closely associated with the development of each of these risk factors. This article uses a case-based approach to discuss the unique features of insulin resistance and type 2 diabetes considered to be key contributors to CVD risk. A systematic approach to both evaluation and management is proposed, with priority given to therapies of demonstrated clinical benefit. Because of its critical and central role in the development of many CVD risk factors, targeted treatment of insulin resistance will also be discussed as such therapy may prove to be a critical component of care in years to come.

Update on the cardiometabolic syndrome

An array of metabolic, hemodynamic, and renal abnormalities constitutes the cardiometabolic syndrome. A hallmark of this syndrome is visceral obesity and associated insulin resistance/hyperinsulinemia. The syndrome is also associated with essential hypertension, abnormalities in the circadian rhythm of blood pressure and heart rate, the diabetic dyslipidemic syndrome, hypercoagulability, hyperuricemia, increased cardiovascular inflammation, and microalbuminuria, all of which contribute to an increased risk of cardiovascular disease morbidity and mortality. This article reviews current knowledge about the interrelationship of the various factors that make up the cardiometabolic syndrome and its implications for individuals with and without diabetes mellitus.

Hostility, the metabolic syndrome, and incident coronary heart disease

This invesgation examined the impact of hostility and the metabolic syndrome on coronary heart disease (CHD) using prospective data from the Normative Aging Study. Seven hundred seventy-four older, unmedicated men free of cardiovascular disease were included in the study. The total Cook-Medley Hostility (Ho) Scale score, anthropometric data, serum lipids, fasting insulin concentrations, blood pressure, cigarette smoking, alcohol consumption, and total dietary calories were used to predict incident CHD during a 3-year follow-up interval. Multivariate analysis indicated that only Ho positively predicted and high-density lipoprotein cholesterol level negatively predicted incident CHD. Ho's effects on CHD may be mediated though mechanisms other than factors that constitute the metabolic syndrome.

Insulin resistance: a metabolic link between depressive disorder and atherosclerotic vascular diseases

The association of depression with insulin resistance (IR) and athersclerotic vascular diseases has been well documented. This review examines the relevance of IR as a link between depressive disorder and atherosclerotic vascular diseases. Relevant articles collected from Medline database over the period of 1966-2001 were reviewed. Studies have shown that IR is a state-dependent abnormality in depression and depression increases the risk of vascular morbidity and mortality. Given that IR is a central component of cardiovascular risk factors, depression-related IR might play a role in the development and progression of coronary and cerebral atherosclerosis in chronic-resistant depression. Further, IR may contribute to the pathophysiology of depressive disorder. In conclusion IR could account for the linkage between depression and atherosclerotic vascular diseases. More studies are needed to examine the importance of improving insulin sensitivity in the treatment of chronic-resistant depression and prevention of depression-related vascular morbidity and mortality.

Prostate cancer: another aspect of the insulin-resistance syndrome?

Insulin resistance and compensatory hyperinsulinaemia are thought to be the underlying factors in the metabolic or insulin-resistance syndrome and can be controlled by diet and exercise. Hyperinsulinaemia has been shown to have a direct effect on the live, suppressing the production of sex hormone-binding globulin (SHBG) and insulin-like growth factor-binding proteins 1 and 2 (IGFBP-1, -2) while stimulating the production of insulin-like growth factor 1 (IGF-1). These factors have been proposed to be important modulators of hormone-related cancers, such as prostate cancer. Men adopting a low-fat diet and daily exercise reduced their levels of serum insulin and IGF-1, while increasing their levels of IGFBP-1 and sex hormone-binding globulin (SHBG). Cell-culture studies with LNCaP prostate cancer cells showed apoptosis of tumour cells and a reduction in serum-stimulated cell growth in the post diet and exercise serum. These results suggest that prostate cancer may be another aspect of the insulin-resistance syndrome and that adopting a low-fat diet combined with regular exercise may reduce the risk for prostate and other hormone-related cancers. This needs to be tested with prospective studies.

Addressing the insulin resistance syndrome: a role for the thiazolidinediones

The global epidemic of type 2 diabetes and cardiovascular disease (CVD) is mirrored by increasing prevalence of the Insulin Resistance Syndrome (IRS) or Metabolic Syndrome. Accumulating data indicate that insulin resistance is the common denominator underlying this cluster of related CVD risk factors. Therapeutic interventions that address insulin resistance and other components of the IRS may be of benefit in reducing the significant health and socioeconomic burden presented by diabetes and CVD. Evidence is discussed that the thiazolidinediones, which improve glycemic control by directly targeting insulin resistance, have the additional benefit of improving many of the CVD risk factors in the IRS, and thus have the potential to reduce CVD in patients with type 2 diabetes.

Obesity and cardiovascular disease

Obesity is a major contributor to the prevalence of cardiovascular disease in the developed world, and yet has only recently been afforded the same level of attention as other risk factors of coronary artery disease. Obesity is a chronic metabolic disorder associated with cardiovascular disease and increased morbidity and mortality. It is apparent that a variety of adaptations/alterations in cardiac structure and function occur as excessive adipose tissue accumulates, even in the absence of comorbidities. Shifts toward a less physically demanding lifestyle are observed today throughout different populations, and this scourge associated with obesity implicates a corresponding increase in the number of individuals afflicted with the metabolic syndrome, which defines the obese patient as being "at risk." Adipose tissue is not simply a passive storehouse for fat, but an endocrine organ that is capable of synthesizing and releasing into the bloodstream a variety of molecules that may impact unfavorably the risk factor profile of a patient. Indeed, obesity may affect atherosclerosis through unrecognized variables and risk factors for coronary artery disease such as dyslipidemia, hypertension, glucose intolerance, inflammatory markers, and the prothrombotic state. By favorably modifying lipids, decreasing blood pressure, and decreasing levels of glycemia, proinflammatory cytokines, and adhesion molecules, weight loss may prevent the progression of atherosclerosis or the occurrence of acute coronary syndrome events in the obese high-risk population.

[Predictive value of insulin-glucose homeostasis markers in patients with metabolic syndrome X]

AIM

To clarify informative value of secretory ability of pancreatic beta-cells and correspondence of insulin values to glycemia in the course of standard glucose tolerance test (GTT) in detection of insulin-resistance in patients with arterial hypertension (AH) to verify metabolic syndrome (MS).

MATERIAL AND METHODS

Correlation and factor analyses were performed of correlations between glycemia, immunoreactive insulin (IRI), C-peptide, glucose/IRI in the course of GTT in 111 AH patients divided into groups by the sum of metabolic disturbances.

RESULTS

The greatest number of correlations were seen for glucose/IRI fasting index. According to the factor analysis, changed sensitivity to insulin and hyperinsulinemia are the first stage of metabolic disturbances in AH irrespective of body mass. In obesity the number of the above correlations is maximal. Multivariance analysis has shown significant differences between AH patients and healthy subjects irrespective of body mass and glucose tolerance.

CONCLUSION

Basal index glucose/IRI < 6 relative units is informative in all the studied variants of metabolic syndrome as regards insulin resistance.

Current concepts in insulin resistance, type 2 diabetes mellitus, and the metabolic syndrome

A clustering of risk factors, including elevated triglycerides, decreased high-density lipoprotein cholesterol, hyperinsulinemia, and hypertension often are observed in patients who are insulin resistant. Insulin resistance has been found to play a critical role in the development of cardiovascular disease, particularly in patients with type 2 diabetes. Patients with insulin resistance have an increase in small, dense low-density lipoprotein (LDL) cholesterol, which is more atherogenic than large, buoyant LDL cholesterol. In the context of insulin resistance, insulin has reduced effects on the phosphatidylinositol 3 kinase (PI3K) pathway, whereas mitogen-activated protein kinase activity is maintained. The result is an exaggeration of the mitogenic actions of insulin leading to vascular smooth muscle proliferation and elevated plasminogen activator inhibitor (PAI)-1. Notably, nitric oxide-mediated vasodilation also is impaired, further contributing to atherogenicity. In addition, hyperinsulinemia further contributes to cardiovascular risk by promoting thrombosis. Patients who are insulin resistant have decreased fibrinolysis, as indicated by increased levels of PAI-1. Studies have shown that enhancing insulin sensitivity with insulin sensitizers, such as thiazolidinediones, may improve insulin resistance and limit the development of adverse cardiovascular consequences.

Interrelationship between serum lipid profile, serum hormones and other components of the metabolic syndrome

The aim of the present study was to investigate the association between the serum lipid profile and components of the metabolic syndrome, such as central obesity (anthropometric, computed tomography and fat cell data), insulin, sex-hormone-binding-globulin (SHBG) and different hormones influencing this important syndrome, e.g. sex steroids, leptin and tumor necrosis factor-alpha (TNF-alpha). The sample consisted of 85 obese patients (30 men and 55 women) who had undergone abdominal surgery. Fasting serum lipids were analysed, as well as anthropometric and computed tomography data, perivisceral and subcutaneous fat cell size and serum glucose and hormones. Abdominal fat revealed itself as an important correlator of the adverse changes in plasma lipoprotein levels, the waist-to-hip-ratio and waist-to-thigh-ratio being the best morphological correlators in men and women, respectively. Intra-abdominal fat (VA) correlated significantly and positively to perivisceral fat cell size in women, while no correlation was found between subcutaneous fat accumulation (SA) and adipocyte size in both genders. Perivisceral fat cell size showed the greatest number of correlations with the adverse plasma lipid profile compared to that in the subcutaneous depot. SHBG and sex steroids showed a negative correlation with serum lipids considered a cardiovascular risk. In contrast, TNF-alpha and C-peptide were inversely correlated with potential protector lipids. In conclusion, abdominal obesity, adipocyte hypertrophy from visceral fat, serum TNF-alpha and C-peptide seem to be the best correlators of the lipoprotein disturbance characteristic of the metabolic syndrome, whereas SHBG and sex steroids could play a protective role regarding the lipid profile associated to this syndrome.

Body fat and cardiovascular risk factors in Indian men in three geographical locations

We studied cardiovascular risk factors in 149 rural, 142 slum dwellers, and 150 urban middle class Indian men (30 to 50 years, mean 40 years) in relation to their body fat. Mean body mass index (BMI) was 21.0, 22.3, and 24.3 kg/m2 and mean body fat percent (bioimpedance) was 20.4, 22.5, and 30.4, respectively. A 75 g oral glucose tolerance test showed no diabetes in rural subjects; 4% of urban slum dwellers and 10% of urban middle class men were diabetic. Hypertension (blood pressure > or = 140/90 mm Hg) was present in 2% of the rural, 4% of the urban slum, and 10% of the urban middle class men. All cardiovascular risk factors were strongly related the percentage of body fat and waist to hip ratio. Two hour plasma glucose concentration and blood pressure were, in addition, independently related to geographical location (urban middle class were higher than slums who were higher than rural men). Our results suggest that urbanization increases the risk of hyperglycemia and hypertension independent of the percentage of body fat or its central distribution.

Total sialic acid and associated elements of the metabolic syndrome in women with and without previous gestational diabetes

OBJECTIVE

Inflammatory markers predict type 2 diabetes and relate to the metabolic syndrome. Gestational diabetes mellitus (GDM) predicts type 2 diabetes and may be part of this syndrome. To examine the association of inflammatory markers with GDM, we investigated total sialic acid (TSA) in women with and without previous GDM.

RESEARCH DESIGN AND METHODS

All women with GDM and a random sample of women from one center of the Brazilian Study of Gestational Diabetes were invited to return 7 years after their index pregnancy. After an interview, an oral glucose tolerance test and anthropometry were performed. A total of 46 women with and 50 women without previous GDM completed the protocol.

RESULTS

Mean TSA was significantly higher in women with (71.8 +/- 11.1 mg/dl) than without (67.5 +/- 9.8 mg/dl) previous GDM (P < 0.05). In a linear regression model, TSA was 4 mg/dl (P < 0.05) higher in women with previous GDM, after adjustment for BMI, fasting insulin sensitivity, and number of years spent in school. In a similar model, current 2-h plasma glucose levels were associated with higher TSA levels after adjustment for waist-to-hip ratio and the log of triglycerides. TSA was strongly correlated with individual components and aggregates (r = 0.55, P < 0.001) of the metabolic syndrome.

CONCLUSIONS

Increased TSA levels are associated with previous GDM and are strongly linked to the metabolic syndrome. These findings in young women suggest that a chronic mild systemic inflammatory response is an early feature of the metabolic syndrome and that GDM may be a window for its investigation.

Epidemiological study on obesity and its comorbidities in urban Chinese older than 20 years of age in Shanghai, China

The aim of this work was to establish the prevalence of overweight and obesity and its associated comorbidities in a Chinese population older than 20 years of age. A group of 2776 randomly selected adults (20-94 years of age) living in the Huayang Community in Shanghai, China, were investigated between 1998 and 2000. Body weight, height, waist and hip circumferences and blood pressure were measured, as were fasting blood glucose, fasting insulin and lipid profile, as well as blood glucose 2 h after a glucose load, and a 75-g glucose tolerance test was performed. The prevalence of overweight was 29.5% and obesity was 4.3%, with a greater number of women being obese than men. More than one-third of the population had abnormal lipid levels. Impaired glucose regulation (IGR) occurred in 10.8%; and 9.8% of the population were classified as having type 2 diabetes mellitus. Hypertension was present in 58.4% of this population. About 21% and 29.3% of the population suffered from high total cholesterol and high triglyceride, respectively. The prevalence of metabolic syndrome was 10.2%. The prevalence of diabetes, IGR and metabolic syndrome increased progressively in association with a body mass index (BMI) of >23 kg m(-2). Hence, although the prevalence of obesity is low in this Chinese population, higher BMI and waist circumference values are clearly associated with an increasing prevalence of comorbidities. The absolute risk of having diabetes, IGR and metabolic syndrome is high in adults with a BMI of > or =23 kg m(-2).

[Hypertension and metabolic syndrome in population of one company. Monotherapy with amlodipine and doxazosin]

In Poland diagnosing of hypertension (HA) and the efficacy of treatment of this condition is still insufficient. Consideration of the concomitant metabolic disorders may help to choose the best line of therapy.

AIM OF THE STUDY

To determine the incidence of HA and concomitant lipid and carbohydrate metabolism disturbances in population of one company. To assess the efficacy of monotherapy of HA and the influence of therapy on some metabolic parameters.

METHODS

The blood pressure was measured in 599 subjects. Patients with HA (> or = 140/90 mmHg) were treated according to metabolic parameters. Patients with fasting total cholesterol (TC) > or = 200 mg% and/or fasting glucose level > or = 110 mg% received doxazosin (D); initial dose 1 mg. The remaining patients received amlodipine (A); initial dose 5 mg.

RESULTS

HA was found in 154 patients (27.5%). In this group, 50 of subjects were unaware of the disease, the remaining 67 (44%) were not treated or treated insufficiently. Elevated glucose and/or TC levels were found in 51% of hypertensives. After one month of treatment with A or D, the mean systolic and diastolic blood pressure decreased significantly (p = 0.001). Monotherapy was effective in 88.9% of subjects in group D and in 92.1% in group A. In group D, TC concentration decreased by 9.5% comparing to baseline (p = 0.001). The tolerance of treatment was similar in both groups.

CONCLUSIONS

One fourth of the examined company population under medical attention of the local health service had HA. One third of HA patients were unaware of the disease. The half of patients with HA had metabolic disorders. Doxazosin and amlodipine were equally effective and well tolerated during one month of treatment. Treatment with doxazosin positively influenced the metabolic profile.

The metabolic syndrome, insulin resistance and cardiovascular disease

In westernised societies the metabolic syndrome (MS) is common and primarily a lifestyle disease with significant morbidity and premature mortality. The main endpoints are related to cardiovascular disease (CVD), especially affecting the heart. Although insulin resistance (and hyperinsulinaemia) is an early marker of MS and future adverse cardiovascular outcomes, it is not known if on its own this is sufficient. The issue is further clouded in prospective studies by the development in study subjects of some, or all of the components of MS, each of which is an independent risk factor for CVD! Therefore, in spite of a number of appropriate long-term observational studies, we are unable to tease out the exact contribution of the individual components of MS, which together are unequivocally responsible for this present-day epidemic of CVD.