Pre-diabetes, metabolic syndrome, and cardiovascular risk

Pre-diabetes represents an elevation of plasma glucose above the normal range but below that of clinical diabetes. Pre-diabetes can be identified as either impaired fasting glucose (IFG) or impaired glucose tolerance (IGT). The latter is detected by oral glucose tolerance testing. Both IFG and IGT are risk factors for type 2 diabetes, and risk is even greater when IFG and IGT occur together. Pre-diabetes commonly associates with the metabolic syndrome. Both in turn are closely associated with obesity. The mechanisms whereby obesity predisposes to pre-diabetes and metabolic syndrome are incompletely understood but likely have a common metabolic soil. Insulin resistance is a common factor; systemic inflammation engendered by obesity may be another. Pre-diabetes has only a minor impact on microvascular disease; glucose-lowering drugs can delay conversion to diabetes, but whether in the long run the drug approach will delay development of microvascular disease is in dispute. To date, the drug approach to prevention of microvascular disease starting with pre-diabetes has not been evaluated. Pre-diabetes carries some predictive power for macrovascular disease, but most of this association appears to be mediated through the metabolic syndrome. The preferred clinical approach to cardiovascular prevention is to treat all the metabolic risk factors. For both pre-diabetes and metabolic syndrome, the desirable approach is lifestyle intervention, especially weight reduction and physical activity. When drug therapy is contemplated and when the metabolic syndrome is present, the primary consideration is prevention of cardiovascular disease. The major targets are elevations of cholesterol and blood pressure.     

HIV therapy,metabolic syndrome,and cardiovascular risk

People with HIV infection have metabolic abnormalities that resemble metabolic syndrome (hypertriglyceridemia, low high-density lipoprotein cholesterol, and insulin resistance), which is known to predict increased risk of cardiovascular disease (CVD). However, there is not one underlying cause for these abnormalities and they are not linked to each other. Rather, individual abnormalities can be affected by the host response to HIV itself, specific HIV drugs, classes of HIV drugs, HIV-associated lipoatrophy, or restoration to health. Furthermore, one component of metabolic syndrome, increased waist circumference, occurs less frequently in HIV infection. Thus, HIV infection supports the concept that metabolic syndrome does not represent a syndrome based on a common underlying pathophysiology. As might be predicted from these findings, the prevalence of CVD is higher in people with HIV infection. It remains to be determined whether CVD rates in HIV infection are higher than might be predicted from traditional risk factors, including smoking.     

The metabolic syndrome and cardiovascular risk

There are four definitions of the metabolic syndrome that have been recommended by the World Health Organization (WHO), the European Group for Study of Insulin Resistance (EGIR), the National Cholesterol Education Program Expert Panel (NCEP), and the American Association of Clinical Endocrinologists (AACE) separately since 1998. The prevalence of the metabolic syndrome reported from different studies has varied widely, mainly because of differences in the definitions of the syndrome and in the characteristics of the populations studied. Prospective studies on the relationship between the metabolic syndrome and cardiovascular risk are still scanty. Results from several studies including a large population-based Italian study, the Framingham Offspring Study, the Botnia Study, the Kuopio Ischemic Heart Disease Study, the National Health and Nutrition Examination Survey II Mortality Study, the San Antonio Heart Study, and the DECODE study have shown that the presence of metabolic syndrome using different definitions is associated with a significantly increased risk of total mortality and cardiovascular morbidity and mortality.     

Addressing the global cardiovascular risk of hypertension, dyslipidemia, diabetes mellitus, and the metabolic syndrome in the southeastern United States, part II: treatment recommendations for management of the global cardiovascular risk of hypertension, dyslipidemia, diabetes mellitus, and the metabolic syndrome

An aggressive global approach to screening and to the management of the metabolic syndrome is recommended to slow the growth of the syndrome throughout the United States. Prevention should begin in childhood with healthy nutrition, daily physical activity, and annual measurement of weight, height, and blood pressure beginning at 3 years of age. Such screenings will identify cardiovascular risk factors early, allow the health care provider to define global cardiovascular risk with the COSEHC Cardiovascular Risk Assessment Tool, and allow treatment of each risk factor. Lifelong lifestyle modifications and pharmacologic therapy will be required in most patients. Antihypertensive therapy for these patients should begin with an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker unless a compelling indication for another drug is present. Metformin should be considered the first drug for glucose control in the patient with type 2 diabetes. A statin should be used initially for hyperlipidemia unless contraindicated. Combinations of antihypertensive, antiglycemic, and lipid-lowering agents will often be required.     

Thyroid diseases, dyslipidemia and cardiovascular risk

By affecting the metabolism of lipids, hypothyroidism accelerates the process of atherogenesis and increases cardiovascular risk. In manifest hypothyroidism the number of LDL receptors in the liver decreases and there is an increase in levels of overall cholesterol, LDL-cholesterol and apolipoprotein B in the blood. Levels of HDL particles remain normal or even rise slightly as a result of reduced activity of the Cholesterol ester transfer protein (CETP) and hepatic lipase. This leads to a reduction in the transport of cholesterol esters from HDL-(2) to VLDL and IDL. Subclinical hypothyroidism also has a negative effect on the lipid profile, but is more likely to lead to pro-atherogenic changes in the proportion of lipid particles than to a reduction in overall cholesterol. Subclinical hypothyroidism leads to the manifestation of certain risk factors of atherosclerosis. Although studies of overall mortality and cardiovascular morbidity have not been completely unanimous in their conclusions, increased cardiovascular risk can be considered likely in subclinical hypothyroidism. It remains an open question whether the treatment of subclinical hypothyroidism with levothyroxine. At present we have only indirect proof from studies that assessed the effect of levothyroxine treatment on risk factors of atherosclerosis. Starting treatment with lipid lowering agents (especially statins) for (sub)clinical hypothyroidism is extremely risky though due to the risk of the development or worsening of myopathy, which is a further cogent argument for the active screening and treatment of(sub)clinical hypothyroidism for all patients with dyslipidemia.     

The metabolic syndrome and related cardiovascular risk

The metabolic syndrome is a complex association of several risk factors including insulin resistance, dyslipidemia, and essential hypertension. Insulin resistance has been associated with sympathetic activation and endothelial dysfunction, which are the main mechanisms involved in the pathophysiology of hypertension and its related cardiovascular risk. According to the Sixth Report of the Joint National Committee, and guidelines of the World Health Organization/International Society of Hypertension, the presence of multiple risk markers suggests that both hypertension and risk factors should be aggressively managed in order to obtain a better outcome. Primary prevention of obesity at different levels—individual, familial, and social—starting early in childhood has proven to be cost effective, and will be mandatory to reduce the world epidemic of obesity and its severe consequences.     

The metabolic syndrome and cardiovascular risk in Cushing's syndrome.

Cushing's syndrome (CS) is characterized by a series of systemic complications that increase cardiovascular risk and cause severe atherosclerotic damage that develops in parallel with an acquired metabolic syndrome. Short-term remission from hypercortisolism improves metabolic and vascular damages, but long-term remission from CS seems to be associated with similar or worse metabolic and vascular damage, probably because of persistent abdominal obesity or insulin resistance years after normalization of cortisol secretion. Study results suggest that an increased cardiovascular risk also may persist in patients who undergo treatment with exogenous glucocorticoids after therapy withdrawal. Considering the many patients subjected to corticosteroid treatment, this could be of great clinical relevance and should be investigated thoroughly.     

Vitamin d, metabolic dyslipidemia, and metabolic syndrome in rheumatoid arthritis

PurposeVitamin D deficiency is a potential risk factor for cardiometabolic disease. We investigated the associations between vitamin D and dyslipidemia and the metabolic syndrome in patients with rheumatoid arthritis, a group at high risk for cardiovascular disease.MethodsSerum 25(OH)vitamin D and lipoprotein levels were measured at baseline in a random sample of 499 participants, ages 18-85 years, enrolled in a randomized trial of golimumab (GOlimumab Before Employing methotrexate as the First-line Option in the treatment of Rheumatoid arthritis of Early onset or GO-BEFORE Trial). Participants had rheumatoid arthritis with active disease, and were naïve to methotrexate and biologic therapies. Multivariable linear regression was performed to assess associations between vitamin D levels and lipoprotein fractions. Multivariable logistic regression was performed to determine the odds of hyperlipidemia and the metabolic syndrome in participants with vitamin D deficiency (<20 ng/mL).ResultsIn multivariable linear regression, vitamin D levels (per 10 ng/mL) were associated inversely with low-density lipoprotein (β: ?0.029 [?0.049, ?0.0091], P = .004) and triglyceride (β: ?0.094 [?0.15, ?0.039] P = .001) levels, adjusted for demographic, cardiovascular, and disease-specific variables. Vitamin D and high-density lipoprotein levels were not associated in univariate or multivariate analyses. Vitamin D deficiency was associated independently with an increased odds of hyperlipidemia (odds ratio 1.72; 95% confidence interval, 1.10-2.45; P = .014) and metabolic syndrome (odds ratio 3.45; 95% confidence interval, 1.75-6.80; P <.001) in adjusted models.ConclusionsIn conclusion, vitamin D deficiency was associated with the metabolic syndrome and dyslipidemia in rheumatoid arthritis, suggesting a potential role in cardiovascular disease risk. Large-scale, prospective studies are needed to determine if vitamin D supplementation improves lipoprotein levels and reduces cardiovascular risk in rheumatoid arthritis.     

Pediatric nonalcoholic fatty liver disease, metabolic syndrome and cardiovascular risk

Nonalcoholic fatty liver disease(NAFLD) encompasses a range of liver histology severity and outcomes in the absence of chronic alcohol use.The mildest form is simple steatosis in which triglycerides accumulate within hepatocytes.A more advanced form of NAFLD,nonalcoholic steatohepatitis,includes inflammation and liver cell injury,progressive to cryptogenic cirrhosis.NAFLD has become the most common cause of chronic liver disease in children and adolescents.The recent rise in the prevalence rates of overweig...     

Circulating CD34+ cells, metabolic syndrome, and cardiovascular risk.

AIMS: Circulating progenitor cells are believed to participate in cardiovascular (CV) homeostasis and their exhaustion has been linked to CV damage. As general agreement on their characterization is lacking, this work was carried out to assess the relationships between different antigenic profiles of progenitor cells and CV risk, with special regard to metabolic syndrome (MetSyn). METHODS AND RESULTS: CD34, CD133, and KDR were used to quantify circulating progenitors in 214 subjects at different levels of CV risk. In a cross-analysis of six different cell subtypes (CD34(+), CD133(+), CD34(+)CD133(+), CD34(+)KDR(+), CD133(+)KDR(+), and CD34(+)CD133(+)KDR(+)), CD34(+) progenitors showed the best correlation with CV parameters and risk estimates. Components of the MetSyn were all characterized by reduction of CD34(+) cells and acted synergistically in decreasing CD34(+) cell count. Moreover, CD34(+) cell count demonstrated a high performance in detecting high CV risk. CONCLUSION: These data demonstrate that CD34 identifies progenitor cells linked to CV risk, showing a close negative correlation between CD34(+) cells and CV risk, as well as a synergic detrimental effect of clustered metabolic components. Progenitor cell count may be used as a surrogate marker of CV risk, whereas extensive antigenic characterization may not be useful for this purpose.     

The insulin-like growth factor system, metabolic syndrome, and cardiovascular disease risk

The metabolic syndrome is a combination of metabolic and clinical features that aggregate in individuals and increase cardiovascular disease (CVD) risk considerably. It is believed, although sometimes controversially, that the underlying basis for this syndrome is insulin resistance (IR) and accompanying compensatory hyperinsulinemia. Insulin and insulin-like growth factors (IGFs) have significant homology and interact with differing affinity with the same receptors. Therefore, their actions can be complementary, and this becomes particularly significant clinico-pathologically when their circulating levels are altered. This review of currently available information attempts to answer the following questions: (1) Is there any evidence for changes in the components of the IGF system in individuals with established CVD or with increased CVD risk as with the metabolic syndrome? (2) What are the underlying mechanisms for interactions, if any, between insulin and the IGF system, in the genesis of CVD? (3) Can knowledge of the pathophysiological changes in the IGF system observed in macrosomic newborn infants and growth hormone (GH)-treated children and adults explain some of the observations in relation to the IGF system and the metabolic syndrome? (4) Can the experimental and clinical evidence adduced from the foregoing be useful in designing novel therapies for the prevention, treatment, and assignment of prognosis in metabolic syndrome-associated disease, particularly ischemic heart disease? To answer these questions, we have performed a literature review using bibliographies from PubMed, Medline, and Google Scholar published within the last 10 years. We suggest that IGF-1 levels are reduced consistently in individuals with the metabolic syndrome and its components and in those with ischemic CVD. Such changes are also seen with GH deficiency in which these changes are partially reversible with GH treatment. Furthermore, changes are seen in levels and interactions of IGF-binding proteins in these disorders, and some of these changes appear to be independent of IGF-binding capability and could potentially impact on risk for the metabolic syndrome and CVD. The promising therapeutic implications of these observations are also discussed.     

Polycystic ovary syndrome, metabolic syndrome, cardiovascular risk and the role of insulin sensitizing agents

The Polycystic Ovary Syndrome (PCOS) affects 6 to 10% of women of childbearing age. Insulin resistance and hyperinsulinemia are present in nearly all PCOS patients and play a central role in the development of both hyperandrogenism and metabolic syndrome (MS). MS occurs in approximately 43% of PCOS patients, raising the cardiovascular risk to up seven fold in these patients. Several serum, functional and structural markers of endothelial dysfunction and subclinical atherosclerosis were described in PCOS patients, even those young and non-obese. However, despite the fact that PCOS adversely affects the cardiovascular profile, long-term studies did not demonstrate a consistent raise in cardiovascular mortality, which seems to be more observed in the post-menopausal period. Recently, oral contraceptives are being substituted for insulin sensitizing agents (metformin and glitazones) in the PCOS treatment, due to their effects on insulin resistance and cardiovascular risk.     

Sympathetic overdrive and cardiovascular risk in the metabolic syndrome.

Sympathetic neural factors are involved in energy balance as well as in blood pressure control. This represents the background for the hypothesis that an adrenergic overdrive may be implicated in the development and/or progression of the metabolic syndrome. Indirect and direct markers of sympathetic drive have confirmed this hypothesis, by showing the occurrence of an adrenergic activation both at the cardiac and peripheral vascular level. It is likely that this sympathetic dysfunction is triggered by reflex mechanisms (arterial baroreceptor impairment), metabolic factors (insulin resistance), and humoral agents (angiotensin II, leptin). The adrenergic overdrive exerts a number of adverse effects on the cardiovascular system, by favoring the genesis of cardiac hypertrophy, vascular hypertrophy, arterial remodeling and endothelial dysfunction and thereby aggravating the already elevated cardiovascular risk profile of the patient. This carries obvious clinical and therapeutic implications, including the suggestion that sympathetic inhibition should be included among the goals of both pharmacological and non-pharmacological interventions employed in the treatment of the metabolic syndrome.