Insulin resistance is not necessarily an essential element of metabolic syndrome

Influence of Cardiometabolic Risk Factors on Platelet Function

Platelets are key players in the thrombotic processes. The alterations of platelet function due to the occurrence of metabolic disorders contribute to an increased trend to thrombus formation and arterial occlusion, thus playing a major role in the increased risk of atherothrombotic events in patients with cardiometabolic risk factors. Several lines of evidence strongly correlate metabolic disorders such as obesity, a classical condition of insulin resistance, dyslipidemia, and impaired glucose homeostasis with cardiovascular diseases. The presence of these clinical features together with hypertension and disturbed microhemorrheology are responsible for the prothrombotic tendency due, at least partially, to platelet hyperaggregability and hyperactivation. A number of clinical platelet markers are elevated in obese and type 2 diabetes (T2DM) patients, including the mean platelet volume, circulating levels of platelet microparticles, oxidation products, platelet-derived soluble P-selectin and CD40L, thus contributing to an intersection between obesity, inflammation, and thrombosis. In subjects with insulin resistance and T2DM some defects depend on a reduced sensitivity to mediators—such as nitric oxide and prostacyclin—playing a physiological role in the control of platelet aggregability. Furthermore, other alterations occur only in relation to hyperglycemia. In this review, the main cardiometabolic risk factors, all components of metabolic syndrome involved in the prothrombotic tendency, will be taken into account considering some of the mechanisms involved in the alterations of platelet function resulting in platelet hyperactivation.

Application of Latent Class Analysis to Identify Metabolic Syndrome Components Patterns in adults: Tehran Lipid and Glucose study

In this study, using latent class analysis (LCA), we investigated whether there are any homogeneous subclasses of individuals exhibiting different profiles of metabolic syndrome (MetS) components. The current study was conducted within the framework of the Tehran Lipid and Glucose Study (TLGS), a population-based cohort including 6448 subjects, aged 20-50 years. We carried out a LCA on MetS components and assessed the association of some demographic and behavioral variables with membership of latent subclasses using multinomial logistic regression. Four latent classes were identified:(1) Low riskclass, with the lowest probabilities for all MetS components (its prevalence rate in men: 29%, women: 64.7%), (2) MetS with diabetes medication (men: 1%, women: 2.3%), (3) Mets without diabetes medication (men: 32%, women: 13.4%), (4) dyslipidemia (men: 38%, women: 19.6%). In men the forth subclass was more significantly associated with being smoker (odds ratio: 4.49; 95% CI: 1.89-9.97). Our study showed that subjects with MetS could be classified in sub-classes with different origins for their metabolic disorders including drug treated diabetes, those with central obesity and dyslipidemia associated with smoking.

Metabolic syndrome and cardiometabolic risk factors among indigenous Malaysians

OBJECTIVES

This study was undertaken to investigate the occurrence of metabolic syndrome (MetS) and cardiovascular disease (CVD) risk in Orang Asli (OA), the indigenous people of Peninsular Malaysia. OA consist of Negrito, Proto-Malay, and Senoi groups who collectively comprise only 0.76% of the population of Peninsular Malaysia. Owing to the challenges in accessing their remote villages, these groups are often excluded in larger government health surveys. Although tropical diseases were scourges in the past, with rapid national development, many OA communities have been gradually urbanized. We believe an epidemiological transition is occurring and non-communicable diseases are on the rise.

STUDY DESIGN

A retrospective cross-sectional study.

METHODS

Indigenous Malaysians (n = 629) from three major groups (Negrito, Proto-Malay, and Senoi) were recruited, after ethics approval and informed consent. Body mass index (BMI), body weight, height, waist circumference, and systolic and diastolic blood pressure were measured, and participants were examined for acanthosis nigricans. Venous blood samples were used for measurements of fasting blood sugar, triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C). Insulin resistance was estimated using a surrogate measurement TG/HDL-C. The ratios of TC to HDL-C, and of LDL-C to HDL-C were determined. MetS was accessed according to the Joint Interim Statement of the IDF Tsak Force on Epidemiology and Prevention.

RESULTS

MetS affected 29.57% of the OA population investigated and was significantly more prevalent (P < 0.05) in women than in men (35.25% vs 21.95%, P < 0.001). MetS prevalence was the highest among the Proto-Malays (39.56%), followed by Negritos (26.35%) and Senois (11.26%). The most prevalent risk factor among the Negritos with MetS was low HDL-C (95.35%), whereas central obesity was the most common risk factor among the Proto-Malays (82.91%). In contrast, hypertension was the commonest risk factor among the Senois with MetS (94.44%). Elevated TG/HDL-C ratios resulted in the highest risk for MetS among the OA population (relative risk [RR] = 7.01, 95% confidence interval [CI] = 3.58-13.72). The risk was almost four-fold among those with high TG (RR = 3.89, 95% CI = 3.08-4.91) and three-fold among those with BMI obesity (RR = 3.37, 95% CI = 2.61-4.36) and central obesity (RR = 2.99, 95% CI = 2.48-3.61).

CONCLUSIONS

This may well be the first comprehensive report about MetS in OA indigenous communities in Malaysia. We have shown that rapidly urbanized OA communities had significant prevalence of MetS and associated cardiometabolic risk factors. Major contributory factors may include changes from previous hunter-gatherer lifestyles and subsistence diets to more urbanized lifestyles and easier access to high calorie foods.

Hepatic function and the cardiometabolic syndrome

Despite skeletal muscle being considered by many as the source of insulin resistance, physiology tells us that the liver is a central and cardinal regulator of glucose homeostasis. This is sometimes underestimated because, in contrast with muscle, investigations of liver function are technically very difficult. Nevertheless, recent experimental and clinical research has demonstrated clearly that, due in part to its anatomic position, the liver is exquisitely sensitive to insulin and other hormonal and neural factors, either by direct intrahepatic mechanisms or indirectly by organ cross-talk with muscle or adipose tissue. Because the liver receives absorbed nutrients, these have a direct impact on liver function, whether via a caloric excess or via the nature of food components (eg, fructose, many lipids, and trans fatty acids). An emerging observation with a possibly great future is the increase in intestinal permeability observed as a consequence of high fat intake or bacterial modifications in microbiota, whereby substances normally not crossing the gut gain access to the liver, where inflammation, oxidative stress, and lipid accumulation leads to fatty liver, a situation observed very early in the development of diabetes. The visceral adipose tissue located nearby is another main source of inflammatory substances and oxidative stress, and also acts on hepatocytes and Kupffer cells, resulting in stimulation of macrophages. Liberation of these substances, in particular triglycerides and inflammation factors, into the circulation leads to ectopic fat deposition and vascular damage. Therefore, the liver is directly involved in the development of the prediabetic cardiometabolic syndrome. Treatments are mainly metformin, and possibly statins and vitamin D. A very promising avenue is treatment of the leaky gut, which appears increasingly to be an important causal factor in hepatic insulin resistance and steatosis.

C-reactive protein concentration as a significant correlate for metabolic syndrome: a Chinese population-based study

Increasing evidence suggests that chronic, low-grade inflammation may be a common soil involving the pathogenesis of metabolic syndrome (MetS) and cardiovascular disease. We examined the association between C-reactive protein (CRP) concentration, an extensively studied biomarker of low-grade inflammation, and the MetS in a representative sample of Chinese adults in Taiwan. We performed a cross-sectional analysis of data from 4234 subjects [mean (±SD) age, 47.1 (±18.2) years; 46.4 % males] who participated in a population-based survey on prevalences of hypertension, hyperglycemia, and hyperlipidemia in Taiwan. CRP levels were measured by the immunoturbidimetric CRP-latex high-sensitivity assay. The MetS was defined by an unified criteria set by several major organizations. Odds ratios (ORs) and 95 % confidence intervals (CIs) were calculated with logistic regression model. Overall, there were 938 subjects with MetS among 4,234 participants, resulting in a prevalence rate of 22.1 %. A significantly progressive increase in the prevalence of MetS across quartiles of CRP was observed (p for trend <0.001). Participants in the second, third, and upper quartiles of CRP had significantly higher risk of having MetS when compared with those in the lowest quartile [adjusted ORs (95 % CIs) were 2.18 (1.62-2.94), 4.39 (3.31-5.81), and 7.11 (5.39-9.38), respectively; p for trend <0.001]. Furthermore, there was a strong stepwise increase in CRP levels as the number of components of the MetS increased. The prevalence of MetS showed a graded increase according to CRP concentrations. The possible utility of CRP concentration as a marker for MetS risk awaits further evaluation in prospective studies.

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.