Race, visceral adipose tissue, plasma lipids, and lipoprotein lipase activity in men and women: the Health, Risk Factors, Exercise Training, and Genetics (HERITAGE) family study

Android and gynoid fat percentages and serum lipid levels in United States adults

CONTEXT

Accumulating evidence suggests that fat distribution is a better predictor of cardiovascular disease than body mass index (BMI).

OBJECTIVE

The aim of this study was to investigate the association of android and gynoid fat percentages with lipid profiles to determine whether android and/or gynoid fat percentages are associated with serum lipid levels.

DESIGN

A population-based cross-sectional study.

PATIENTS

Five thousand six hundred and ninety-six adults (20 years and older) who participated in the National Health and Nutrition Examination Survey 2003-2006.

MEASUREMENT

The regional body composition in the android and gynoid regions was defined by dual energy X-ray absorptiometry (DXA). The estimation of lipid risk profiles included total cholesterol, high-density lipoprotein (HDL) -cholesterol, low-density lipoprotein (LDL) -cholesterol and triglycerides (TG).

RESULTS

Regardless of gender, android and gynoid body fat percentages were positively and significantly correlated with BMI and waist circumference. After adjustment for age, ethnicity, education, smoking, alcohol consumption, dyslipidaemia and BMI, increases in android fat percentage were significantly associated with total cholesterol, TG and HDL cholesterol in males, and total cholesterol, HDL cholesterol and LDL cholesterol in females. The gynoid fat percentages showed a positive correlation with total cholesterol in males, whereas gynoid fat accumulation in females showed a favourable association with TG and HDL cholesterol. The observed associations differed according to ethnic groups.

CONCLUSION

Our results suggest that regional fat distribution in the android and gynoid regions have different effects on lipid profiles, and that fat in the android region, rather than the gynoid region, may be an important factor in determining the risk of cardiovascular disease.

Ethnic differences in associations between fat deposition and incident diabetes and underlying mechanisms: the SABRE study

OBJECTIVE

To examine ethnic differences in ectopic fat and associations with incident diabetes.

METHODS

In a UK cohort study, 1338 Europeans, 838 South Asians, and 330 African Caribbeans living in London were aged 40-69 years at baseline. Baseline assessment included blood tests, anthropometry, and questionnaires. Anthropometry-based prediction equations estimated baseline visceral adipose tissue (VAT). Incident diabetes was ascertained from record review, self-report, or oral glucose tolerance testing.

RESULTS

South Asians had more and African Caribbeans less estimated VAT than Europeans. Both ethnic minorities had larger truncal skinfolds than Europeans. In men, adjustment for risk factors (BMI, smoking, systolic blood pressure, and HDL-cholesterol) markedly attenuated the association between estimated VAT and diabetes in Europeans (standardized subhazard ratios [95% CI]: from 1.74 [1.49, 2.03] to 1.16 [0.77, 1.76]) and African Caribbeans (1.72 [1.26, 2.35] to 1.44 [0.69, 3.02]) but not South Asians (1.60 [1.38, 1.86] to 1.90 [1.37, 2.64]). In women, attenuation was observed only for South Asians (1.80 [1.01, 3.23] to 1.07 [0.49, 2.31]). Associations between truncal skinfolds and diabetes appeared less affected by multivariable adjustment in South Asians and African Caribbeans than Europeans (1.24 [0.97, 1.57] and 1.28 [0.89, 1.82] versus 1.02 [0.77, 1.36] in men; 1.91 [1.03, 3.56] and 1.42 [0.86, 2.34] versus 1.23 [0.74, 2.05] in women).

CONCLUSIONS

Differences in overall truncal fat, as well as VAT, may contribute to the excess of diabetes in South Asian and African Caribbean groups, particularly for women.

Metabolic syndrome and lifestyle modification

A clustering of metabolic abnormalities such as dyslipidemia, hypertension, and diabetes mellitus, all of which are major risk factors for cardiovascular disease (CVD), occurs more often than by chance. Numerous epidemiological studies, as well as basic researches, have revealed that visceral fat accumulation is closely involved in this risk clustering. This morbid condition is now well recognized as the metabolic syndrome. The concept of the metabolic syndrome, i.e., the involvement of visceral adiposity in the clustering of CVD risk factors, implies that an effective CVD risk reduction will be accomplished by an intervention to reduce visceral fat deposits. The primary strategy of the intervention is lifestyle modification, which can be put into practice in healthcare fields, without necessity of medical treatment. Now that CVD is a leading global health burden, the metabolic syndrome attracts increasing attention in the world. To take global action against the syndrome, several working groups developed its internationally unified diagnostic criteria. Most recently, the International Diabetes Federation (IDF) and the American Heart Association/National Heart, Lung, and Blood Institute (AHA/NHLBI) jointly proposed the criteria, although some cautions will be needed in their practical use. In this review, we mainly focus on the findings observed in clinical and epidemiological studies, to discuss a practical strategy of the management of the metabolic syndrome in healthcare fields.

Obesity-induced increases in sympathetic nerve activity: sex matters

Abundant evidence obtained largely from male human and animal subjects indicates that obesity increases sympathetic nerve activity (SNA), which contributes to hypertension development. However, recent studies that included women reported that the strong relationships between muscle SNA and waist circumference or body mass index (BMI) found in men are not present in overweight and obese women. A similar sex difference in the association between adiposity and hypertension development has been identified in animal models of obesity. In this brief review, we consider two possible mechanisms for this sex difference. First, visceral adiposity, leptin, insulin, and angiotensin II have been identified as potential culprits in obesity-induced sympathoexcitation in males. We explore if these factors wield the same impact in females. Second, we consider if sex differences in vascular reactivity to sympathetic activation contribute. Our survey of the literature suggests that premenopausal females may be able to resist obesity-induced sympathoexcitation and hypertension in part due to differences in adipose disposition as well as its muted inflammatory response and reduced production of pressor versus depressor components of the renin-angiotensin system. In addition, vascular responsiveness to increased SNA may be reduced. However, more importantly, we identify the urgent need for further study, not only of sex differences per se, but also of the mechanisms that may mediate these differences. This information is required not only to refine treatment options for obese premenopausal women but also to potentially reveal new therapeutic avenues in obese men and women.

Consequences of Abdominal Adiposity within the Metabolic Syndrome Paradigm in Black People of African Ancestry

The metabolic syndrome (MetS) is a constellation of risk factors that are associated with increased risks for coronary heart disease and type 2 diabetes. Although the cause is unknown, abdominal adiposity is considered the underpinning of these metabolic alterations. Hence, increased abdominal adiposity contributes to dyslipidemia, hyperglycemia, beta cell dysfunction, insulin resistance, hypertension and inflammation. The role of abdominal adiposity in the causation of metabolic alterations that lead to the clinical expression of the MetS has become a focus of active research. In addition, there are ethnic/racial differences in the manifestation of the MetS. Therefore, the focus of this current review is to: (1) explore the consequences of abdominal obesity within the MetS paradigm; and (2) discuss the impact of ethnicity/race on MetS in Black People of African Ancestry (PAA).

Interleukin-6 gene polymorphisms, dietary fat intake, obesity and serum lipid concentrations in black and white South African women

This study investigated interactions between dietary fat intake and IL-6 polymorphisms on obesity and serum lipids in black and white South African (SA) women. Normal-weight and obese, black and white women underwent measurements of body composition, serum lipids and dietary fat intake, and were genotyped for the IL-6 -174 G>C, IVS3 +281 G>T and IVS4 +869 A>G polymorphisms. In black women the IVS4 +869 G allele was associated with greater adiposity, and with increasing dietary fat intake adiposity increased in the IVS3 +281 GT+GG and IVS4 +869 AA or AG genotypes. In white women, with increasing omega-3 (n-3) intake and decreasing n-6:n-3 ratio, body mass index (BMI) decreased in those with the -174 C allele, IVS3 +281 T allele and IVS4 +869 AG genotype. In the white women, those with the IVS3 +281 T allele had lower triglycerides. Further, with increasing n-3 polyunsaturated fatty acid (PUFA); triglyceride and total cholesterol:high-density lipoprotein cholesterol (T-C:HDL-C) ratio decreased in those with the -174 C allele. In black women, with increasing total fat intake, triglycerides and T-C:HDL-C ratio increased in those with the IVS4 +869 G allele. This study is the first to show that dietary fat intake modulates the relationship between the IL-6 -174 G>C, IVS3 +281 G>T and IVS4 +869 A>G polymorphisms on obesity and serum lipids in black and white SA women.

Meeting physical activity guidelines is associated with reduced risk for cardiovascular disease in black South African women; a 5.5-year follow-up study

Background

Low levels of physical activity (PA) have been associated with increased risk for cardiovascular disease (CVD) and type 2 diabetes (T2D), but few studies have examined whether meeting international PA guidelines is associated with reduced risk in a black South African (SA) population. The aims of this study were to compare body composition and cardio-metabolic risk factors for CVD and T2D between active and inactive groups (part 1, cross-sectional analysis) and, to determine whether PA level predicts changes in body composition and cardio-metabolic risk factors for CVD and T2D at follow-up after 5.5-years (part 2, longitudinal analysis).

Methods

Part 1 included a sample of 240 apparently healthy black SA women (26 ± 7 years) who underwent the following measurements at baseline: PA (Global Physical Activity Questionnaire (GPAQ)), body composition and regional fat distribution (dual-energy x-ray absorptiometry and computerised tomography), blood pressure, fasting glucose, insulin and lipid concentrations. For part 2, a sub-sample of women (n = 57) underwent the same measurements after a 5.5-year period.

Results

At baseline, 61% of women were classified as meeting the guidelines for moderate- to vigorous-intensity physical activity (MVPA) according to GPAQ. Women who were active had significantly lower body weight (p < 0.001), body fat (BMI, fat mass, % body fat, waist circumference, central and appendicular fat mass, all p < 0.001), and measures of insulin resistance (fasting serum insulin and HOMA-IR, both p = 0.01), and higher high-density lipoprotein cholesterol (p = 0.041), compared to the inactive group. At follow-up, all body fat measures increased significantly in both groups and diastolic blood pressure decreased significantly in those who were active at baseline, but did not change in those who were inactive.

Conclusions

Meeting PA guidelines was associated with decreased risk for CVD and T2D in black SA women, but did not prevent the increase in body fat over time. Interventions promoting physical activity to specifically address obesity in this high-risk group are recommended.

Ethnic and sex differences in fatty liver on cardiac computed tomography: the multi-ethnic study of atherosclerosis

OBJECTIVE

To describe ethnic and sex differences in the prevalence and determinants of fatty liver in a multiethnic cohort.

PATIENTS AND METHODS

We studied participants of the Multi-Ethnic Study of Atherosclerosis who underwent baseline noncontrast cardiac computed tomography between July 17, 2000, and August 29, 2002, and had adequate hepatic and splenic imaging for fatty liver determination (n=4088). Fatty liver was defined as a liver/spleen attenuation ratio of less than 1. We compared the prevalence and severity of fatty liver, in 4 ethnicities (white, Asian, African American, and Hispanic), and the factors associated with fatty liver in each ethnicity, stratifying by obesity and metabolic syndrome. Multivariable ordinal logistic regression was used to determine the effect of cardiometabolic risk factors on the prevalence of fatty liver in different ethnicities.

RESULTS

The prevalence of fatty liver varied significantly by ethnicity (African American, 11%; white, 15%; Asian, 20%; and Hispanic, 27%; P<.001). Although African Americans had the highest prevalence of obesity, a smaller percentage of obese African Americans received a diagnosis of fatty liver than did other ethnicities (African American, 17%; white, 31%; Asian, 37%; and Hispanic 39%; P<.001). Hispanics had the highest prevalence of fatty liver, including the obese and metabolic syndrome population. An increase in insulin resistance predicted a 2-fold increased prevalence of fatty liver in all ethnicities after multivariable adjustment.

CONCLUSION

African Americans have a lower prevalence and Hispanics have a higher prevalence of fatty liver than do other ethnicities. There are distinct ethnic variations in the prevalence of fatty liver even in patients with the metabolic syndrome or obesity, suggesting that genetic factors may play a substantial role in the phenotypic expression of fatty liver.

Persistently high hip circumference after bariatric surgery is a major hurdle to successful hip replacement

The prevalence of class III obesity (BMI ≥ 40 kg/m²) in black women is 18%. As class III obesity leads to hip joint deterioration, black women frequently present for orthopedic care. Weight loss associated with bariatric surgery should lead to enhanced success of hip replacements. However, we present a case of a black woman who underwent Roux-en-Y gastric bypass with the expectation that weight loss would make her a better surgical candidate for hip replacement. Her gastric bypass was successful as her BMI declined from 52.0 kg/m² to 33.7 kg/m². However, her hip circumference after weight loss remained persistently high. Therefore, at surgery the soft tissue tunnel geometry presented major challenges. Tunnel depth and immobility of the soft tissue interfered with retractor placement, tissue reflection, and surgical access to the acetabulum. Therefore a traditional cup placement could not be achieved. Instead, a hemiarthroplasty was performed. After surgery her pain and reliance on external support decreased. But her functional independence never improved. This case demonstrates that a lower BMI after bariatric surgery may improve the metabolic profile and decrease anesthesia risk, but the success of total hip arthroplasties remains problematic if fat mass in the operative field (i.e., high hip circumference) remains high.

Differential associations of abdominal visceral, subcutaneous adipose tissue with cardiometabolic risk factors between African and European Americans

OBJECTIVE

To examine the relative association of abdominal visceral adipose tissue (VAT) with cardiometabolic risk factors between African and European Americans.

METHODS

A cross-sectional study of 2,035 African Americans from the Jackson Heart Study (JHS) and 3,170 European Americans from the Framingham Heart Study (FHS) who underwent computed tomography assessment of VAT and subcutaneous adipose tissue (SAT) was conducted. The FHS participants were weighted to match the age distribution of the JHS participants, and the metabolic risk factors were examined by study groups in relation to VAT.

RESULTS

JHS participants had higher rates of obesity, hypertension, diabetes, and metabolic syndrome than FHS participants (all P = 0.001). The associations were weaker in JHS women for VAT with blood pressure, triglycerides, HDL-C, and total cholesterol (Pinteraction = 0.03-0.001) than FHS women. In contrast, JHS men had stronger associations for VAT with high triglycerides, low HDL, and metabolic syndrome (all Pinteraction = 0.001) compared to FHS men. Similar associations and gender patterns existed for SAT with most metabolic risk factors.

CONCLUSIONS

The relative association between VAT and cardiometabolic risk factors is weaker in JHS women compared to FHS women, whereas stronger associations with triglycerides and HDL were observed in JHS men.

Interethnic Variation in Lipid Profiles: Implications for Underidentification of African-Americans at risk for Metabolic Disorders

Interethnic differences exist in the distribution of serum lipids, with African Americans (AA) generally having a healthier lipid profile than other US ethnic groups. Similar lipid distributions are observed among other African ancestry groups with distinct lifestyle characteristics, suggesting the importance of inherited factors. Despite healthier serum lipids, AA experience a disproportionate burden of Type 2 Diabetes and Cardiovascular Disease. As evidence of a different relationship between serum lipids and disease exists, the characterization of metabolic risk using lipid concentration (as in Metabolic Syndrome criteria) may lead to the under-identification of AA at risk. Given the disproportionately high rate of metabolic disorders in AA, understanding interethnic differences in the association between serum lipids and disease should be a research priority, as better appreciation of these differences will enhance knowledge of disease etiology, improve intervention targeting, and may lead to mechanisms to ameliorate debilitating health disparities in the US and globally.

Application of alternative anthropometric measurements to predict metabolic syndrome

OBJECTIVE

The association between rarely used anthropometric measurements (e.g., mid-upper arm, forearm, and calf circumference) and metabolic syndrome has not been proven. The aim of this study was to assess whether mid-upper arm, forearm, calf, and waist circumferences, as well as waist/height ratio and waist-to-hip ratio, were associated with metabolic syndrome.

METHODS

We enrolled 387 subjects (340 women, 47 men) who were admitted to the obesity outpatient department of Istanbul Medeniyet University Goztepe Training and Research Hospital between September 2010 and December 2010. The following measurements were recorded: waist circumference, hip circumference, waist/height ratio, waist-to-hip ratio, mid-upper arm circumference, forearm circumference, calf circumference, and body composition. Fasting blood samples were collected to measure plasma glucose, lipids, uric acid, insulin, and HbA1c.

RESULTS

The odds ratios for visceral fat (measured via bioelectric impedance), hip circumference, forearm circumference, and waist circumference/hip circumference were 2.19 (95% CI, 1.30-3.71), 1.89 (95% CI, 1.07-3.35), 2.47 (95% CI, 1.24-4.95), and 2.11(95% CI, 1.26-3.53), respectively. The bioelectric impedance-measured body fat percentage correlated with waist circumference only in subjects without metabolic syndrome; the body fat percentage was negatively correlated with waist circumference/hip circumference in the metabolic syndrome group. All measurements except for forearm circumference were equally well correlated with the bioelectric impedance-measured body fat percentages in both groups. Hip circumference was moderately correlated with bioelectric impedance-measured visceral fat in subjects without metabolic syndrome. Muscle mass (measured via bioelectric impedance) was weakly correlated with waist and forearm circumference in subjects with metabolic syndrome and with calf circumference in subjects without metabolic syndrome.

CONCLUSION

Waist circumference was not linked to metabolic syndrome in obese and overweight subjects; however, forearm circumference, an unconventional but simple and appropriate anthropometric index, was associated with metabolic syndrome and bioelectric impedance-measured visceral fat, hip circumference, and waist-to-hip ratio.

Obesity and mortality after breast cancer by race/ethnicity: The California Breast Cancer Survivorship Consortium

We investigated body size and survival by race/ethnicity in 11,351 breast cancer patients diagnosed from 1993 to 2007 with follow-up through 2009 by using data from questionnaires and the California Cancer Registry. We calculated hazard ratios and 95% confidence intervals from multivariable Cox proportional hazard model-estimated associations of body size (body mass index (BMI) (weight (kg)/height (m)(2)) and waist-hip ratio (WHR)) with breast cancer-specific and all-cause mortality. Among 2,744 ascertained deaths, 1,445 were related to breast cancer. Being underweight (BMI <18.5) was associated with increased risk of breast cancer mortality compared with being normal weight in non-Latina whites (hazard ratio (HR) = 1.91, 95% confidence interval (CI): 1.14, 3.20), whereas morbid obesity (BMI ≥ 40) was suggestive of increased risk (HR = 1.43, 95% CI: 0.84, 2.43). In Latinas, only the morbidly obese were at high risk of death (HR = 2.26, 95% CI: 1.23, 4.15). No BMI-mortality associations were apparent in African Americans and Asian Americans. High WHR (quartile 4 vs. quartile 1) was associated with breast cancer mortality in Asian Americans (HR = 2.21, 95% CI: 1.21, 4.03; P for trend = 0.01), whereas no associations were found in African Americans, Latinas, or non-Latina whites. For all-cause mortality, even stronger BMI and WHR associations were observed. The impact of obesity and body fat distribution on breast cancer patients' risk of death may vary across racial/ethnic groups.

Sex-specific differences in lipid and glucose metabolism

Energy metabolism in humans is tuned to distinct sex-specific functions that potentially reflect the unique requirements in females for gestation and lactation, whereas male metabolism may represent a default state. These differences are the consequence of the action of sex chromosomes and sex-specific hormones, including estrogens and progesterone in females and androgens in males. In humans, sex-specific specialization is associated with distinct body-fat distribution and energy substrate-utilization patterns; i.e., females store more lipids and have higher whole-body insulin sensitivity than males, while males tend to oxidize more lipids than females. These patterns are influenced by the menstrual phase in females, and by nutritional status and exercise intensity in both sexes. This minireview focuses on sex-specific mechanisms in lipid and glucose metabolism and their regulation by sex hormones, with a primary emphasis on studies in humans and the most relevant pre-clinical model of human physiology, non-human primates.

Adiponectin and waist circumference as predictors of insulin-resistance in women

BACKGROUND AND AIMS

The initial disturbance of insulin resistance seems to focus on adipose tissue is a dynamic organ involved in many physiological and metabolic processes. Expresses and secretes a variety of active peptides, adipocytokines. To evaluate the prevalence of insulin-resistance in an healthy urban middle age population and to explore the role of adiponectin, inflammatory biomarkers (hs-CRP) and traditional cardiovascular risk factors as predictors of the insulin-resistance state.

MATERIALS AND METHODS

We studied of 176 participants (117 women and 59 men, 25-74 years), individuals with diabetes, hypothyroidism or hyperthyroidism, infectious disease, renal, or hepatic neoplasms and pregnant women were excluded. We evaluated glucose, insulin, adiponectin and hs-CRP.

RESULTS

We found that 17.2% of individuals presented insulin-resistance. Correlation was found between waist circumference, body mass index, blood pressure and HOMA index (p<0.01). Adiponectin was associated with the insulin-resistance (p<0.001) but not hs-CRP. Adiponectin (β=0.385, p=0.004) and waist circumference (β=0.116, p=0.02) were predictors of IR only in women, meanwhile none of the analyzed biomarkers predicted insulin-resistance in men. Besides, postmenopausal women presented higher adiponectin levels than premenopausal 7.63 (4.46-9.58) vs 5.50 (3.83-7.40) μg/ml, p=0.01.

CONCLUSIONS

Adiponectin and waist circumference are important predictors of insulin-resistance even in healthy non-diabetic women, they may open a new opportunity to improve current risk estimation.

The TG/HDL-C Ratio Might Be a Surrogate for Insulin Resistance in Chinese Nonobese Women

Obejective. To examine the discriminatory power of triglyceride (TG) and triglyceride to high-density lipoprotein cholesterol ratio (TG/HDL-C) for insulin resistance (IR) in a normoglycaemic Chinese population. Methods. The data were collected from 711 individuals. The normoglycaemic individuals were eventually included in the study (n = 533, age: 62.8 ± 6.6 years, male: 56.8%), who were with a fasting plasma glucose < 6.1 mmol/L and without a history of diabetes. IR was defined as the upper quintile (≥1.6) of homeostasis model assessment of IR. Area under the receiver operating characteristic curve (AROC) was used to examine the discriminatory power. Results. The discriminatory power of TG/HDL-C for IR was acceptable in women with a BMI < 24 kg/m(2) or waist circumference < 80 cm (AROCs: 0.718 and 0.713, resp.); however, the discriminatory power was not acceptable in the obese women. TG/HDL-C was not an acceptable marker of IR in men. The discriminatory power of TG for IR was not acceptable in both men and women. Conclusions. The discriminatory power of TG/HDL-C for IR differs by gender and obesity index in the normoglycaemic Chinese population, and TG/HDL-C could discriminate IR in the nonobese and normoglycaemic women.

The relationship between dietary fatty acids and inflammatory genes on the obese phenotype and serum lipids

Obesity, a chronic low-grade inflammatory condition is associated with the development of many comorbidities including dyslipidemia. This review examines interactions between single nucleotide polymorphisms (SNP) in the inflammatory genes tumor necrosis alpha (TNFA) and interleukin-6 (IL-6) and dietary fatty acids, and their relationship with obesity and serum lipid levels. In summary, dietary fatty acids, in particular saturated fatty acids and the omega-3 and omega-6 polyunsaturated fatty acids, impact the expression of the cytokine genes TNFA and IL-6, and alter TNFα and IL-6 production. In addition, sequence variants in these genes have also been shown to alter their gene expression and plasma levels, and are associated with obesity, measures of adiposity and serum lipid concentrations. When interactions between dietary fatty acids and TNFA and IL-6 SNPs on obesity and serum lipid were analyzed, both the quantity and quality of dietary fatty acids modulated the relationship between TNFA and IL-6 SNPs on obesity and serum lipid profiles, thereby impacting the association between phenotype and genotype. Researching these diet–gene interactions more extensively, and understanding the role of ethnicity as a confounder in these relationships, may contribute to a better understanding of the inter-individual variability in the obese phenotype.

Sex dimorphism and depot differences in adipose tissue function

Obesity, characterized by excessive adiposity, is a risk factor for many metabolic pathologies, such as type 2 diabetes mellitus (T2DM). Numerous studies have shown that adipose tissue distribution may be a greater predictor of metabolic health. Upper-body fat (visceral and subcutaneous abdominal) is commonly associated with the unfavorable complications of obesity, while lower-body fat (gluteal-femoral) may be protective. Current research investigations are focused on analyzing the metabolic properties of adipose tissue, in order to better understand the mechanisms that regulate fat distribution in both men and women. This review will highlight the adipose tissue depot- and sex-dependent differences in white adipose tissue function, including adipogenesis, adipose tissue developmental patterning, the storage and release of fatty acids, and secretory function. This article is part of a Special Issue entitled: Modulation of Adipose Tissue in Health and Disease.

Clinical utility of visceral adipose tissue for the identification of cardiometabolic risk in white and African American adults

BACKGROUND

Visceral adipose tissue (VAT) has been identified as a harmful fat depot, and sex and race differences in VAT have been reported in white and African Americans.

OBJECTIVES

We determined the clinical utility of VAT in the identification of individuals at elevated cardiometabolic risk in white and African American adults and compared the clinical utility with measures obtained by using dual-energy X-ray absorptiometry (DXA) and anthropometric measures.

DESIGN

The sample included 429 white women, 311 African American women, 406 white men, and 100 African American men who were 18-74 y of age. VAT was measured by using computed tomography, fat mass (FM) and percentage of body fat were measured by using DXA, and waist circumference (WC) and BMI were assessed. Receiver operating characteristic curves were used to compare the utility of measures in the identification of participants in the upper quintile of a continuous score derived from principal components analysis of fasting glucose, HDL cholesterol, triglycerides, and blood pressure.

RESULTS

The clinical utility of measures varied across sex-by-race groups. In the overall sample, the areas under the curve were significantly higher for VAT and WC in comparison with the other indicators. Identified VAT thresholds were higher in white men (140 cm(2)) and women (141 cm(2)) than in African American men (82 cm(2)) and women (97 cm(2)).

CONCLUSIONS

VAT and WC showed greater clinical utility than did other obesity measures. Because of the complexity of measuring VAT, the use of WC is recommended for the identification of adults with elevated cardiometabolic risk factors. The Pennington Center Longitudinal Study was registered at clinicaltrials.gov as NCT00959270.

Pathophysiology of human visceral obesity: an update

Excess intra-abdominal adipose tissue accumulation, often termed visceral obesity, is part of a phenotype including dysfunctional subcutaneous adipose tissue expansion and ectopic triglyceride storage closely related to clustering cardiometabolic risk factors. Hypertriglyceridemia; increased free fatty acid availability; adipose tissue release of proinflammatory cytokines; liver insulin resistance and inflammation; increased liver VLDL synthesis and secretion; reduced clearance of triglyceride-rich lipoproteins; presence of small, dense LDL particles; and reduced HDL cholesterol levels are among the many metabolic alterations closely related to this condition. Age, gender, genetics, and ethnicity are broad etiological factors contributing to variation in visceral adipose tissue accumulation. Specific mechanisms responsible for proportionally increased visceral fat storage when facing positive energy balance and weight gain may involve sex hormones, local cortisol production in abdominal adipose tissues, endocannabinoids, growth hormone, and dietary fructose. Physiological characteristics of abdominal adipose tissues such as adipocyte size and number, lipolytic responsiveness, lipid storage capacity, and inflammatory cytokine production are significant correlates and even possible determinants of the increased cardiometabolic risk associated with visceral obesity. Thiazolidinediones, estrogen replacement in postmenopausal women, and testosterone replacement in androgen-deficient men have been shown to favorably modulate body fat distribution and cardiometabolic risk to various degrees. However, some of these therapies must now be considered in the context of their serious side effects. Lifestyle interventions leading to weight loss generally induce preferential mobilization of visceral fat. In clinical practice, measuring waist circumference in addition to the body mass index could be helpful for the identification and management of a subgroup of overweight or obese patients at high cardiometabolic risk.

Gender differences in the association of visceral and subcutaneous adiposity with adiponectin in African Americans: the Jackson Heart Study

BACKGROUND

Adiponectin, paradoxically reduced in obesity and with lower levels in African Americans (AA), modulates several cardiometabolic risk factors. Because abdominal visceral adipose tissue (VAT), known to be reduced in AA, and subcutaneous adipose tissue (SAT) compartments may confer differential metabolic risk profiles, we investigated the associations of VAT and SAT with serum adiponectin, separately by gender, with the hypothesis that VAT is more strongly inversely associated with adiponectin than SAT.

METHODS

Participants from the Jackson Heart Study, an ongoing cohort of AA (n = 2,799; 64% women; mean age, 55 ± 11 years) underwent computer tomography assessment of SAT and VAT volumes, and had stored serum specimens analyzed for adiponectin levels. These levels were examined by gender in relation to increments of VAT and SAT.

RESULTS

Compared to women, men had significantly lower mean levels of adiponectin (3.9 ± 3.0 μg/mL vs. 6.0 ± 4.4 μg/mL; p < 0.01) and mean volume of SAT (1,721 ± 803 cm(3) vs. 2,668 ± 968 cm(3); p < 0.01) but significantly higher mean volume of VAT (884 ± 416 cm(3) vs. 801 ± 363 cm(3); p < 0.01). Among women, a one standard deviation increment in VAT was inversely associated with adiponectin (β = - 0.13; p < 0.0001) after controlling for age, systolic blood pressure, fasting plasma glucose, high-density lipoprotein cholesterol, triglycerides, education, pack-years of smoking and daily intake of alcohol. The statistically significant inverse association of VAT and adiponectin persisted after additionally adjusting for SAT, body mass index (BMI) and waist circumference (WC), suggesting that VAT provides significant information above and beyond BMI and WC. Among men, after the same multivariable adjustment, there was a direct association of SAT and adiponectin (β = 0.18; p = 0.002) that persisted when controlling for BMI and WC, supporting a beneficial effect of SAT. Insulin resistance mediated the association of SAT with adiponectin in women.

CONCLUSION

In African Americans, abdominal visceral adipose tissue had an inverse association with serum adiponectin concentrations only among women. Abdominal subcutaneous adipose tissue appeared as a protective fat depot in men.

Metabolic syndrome in the prevention of cardiovascular diseases and diabetes--still a matter of debate?

After metabolic syndrome was first introduced to identify persons at greater cardiovascular disease (CVD) risk, it has been associated with an increased risk of CVD and type 2 diabetes (T2D). Obesity has been considered as the fundamental factor in metabolic syndrome and it is thought to be mediated, at least in part by the role of the adipocyte in controlling circulating free fatty acids and the development of insulin resistance. However, the obese population is not perfectly overlapped with the population with metabolic syndrome. Is metabolic syndrome a better predictor than obesity to prevent CVD and T2D? Has metabolic syndrome been considered as a cluster of risk factors or an additional independent risk factor to assess CVD and T2D risk? The debate on the necessity of metabolic syndrome diagnosis seems not to be ended. Various definitions of metabolic syndrome were advocated by different organizations with emphasis on different components, and these definitions have different abilities to predict CVD and T2D among different populations because of fundamental philosophical differences. In the definitions of metabolic syndrome, only the cutoffs of each component were presented but rather continuous values or the degree of the severity of the syndrome with multiple cutoffs. Moreover, metabolic syndrome did not incorporate all the risk factors as known for CVD and T2D, such as physical activity. Future prospective studies with the measurement of sophisticated metabolic markers and of abdominal visceral and subcutaneous adiposity are needed to examine if the metabolic syndrome is a good CVD and T2D risk predictor over obesity and other risk factors. In practice, prevention action should be taken at the stage of obesity and providers need to pay attention to any components in the definition of metabolic syndrome even if the number of positive components has not achieved three or more.

The effect of exercise on visceral adipose tissue in overweight adults: a systematic review and meta-analysis

Excessive visceral adipose tissue appears to trigger a cascade of metabolic disturbances that seem to coexist with ectopic fat storage in muscle, liver, heart and the ß-cell. Therefore, the reduction of visceral adipose tissue potentially plays a pivotal role in the treatment of the metabolic syndrome. The purpose of this systematic review and meta-analysis is to describe the overall effect of exercise on visceral adipose tissue and to provide an overview of the effect of different exercise regimes, without caloric restriction, on visceral adipose tissue in obese persons. A systematic literature search was performed according to the PRISMA statement for reporting systematic reviews and meta-analyses. The initial search resulted in 87 articles after removing duplicates. After screening on title, abstract and full-text 15 articles (totalling 852 subjects) fulfilled the a priori inclusion criteria. The quality of each eligible study was assessed in duplicate with “The Critical Review Form for Quantitative Studies”. Using random-effects weights, the standardized mean difference (Hedge's g) of the change in visceral adipose tissue was −0.497 with a 95% confidence interval of −0.655 to −0.340. The Z-value was −6.183 and the p-value (two tailed) was <0.001. A subgroup analysis was performed based on gender, type of training and intensity. Aerobic training of moderate or high intensity has the highest potential to reduce visceral adipose tissue in overweight males and females. These results suggest that an aerobic exercise program, without hypocaloric diet, can show beneficial effects to reduce visceral adipose tissue with more than 30 cm² (on CT analysis) in women and more than 40 cm² in men, even after 12 weeks.

Adipokine inflammation and insulin resistance: the role of glucose, lipids and endotoxin

Adipose tissue is an active endocrine organ, and our knowledge of this secretory tissue, in recent years, has led us to completely rethink how our body functions and becomes dysregulated with weight gain. Human adipose tissue appears to act as a multifunctional secretory organ with the capacity to control energy homoeostasis through peripheral and central regulation of energy homoeostasis. It also plays an important role in innate immunity. However, the capability to more than double its original mass to cope with positive energy balance in obesity leads to many pathogenic changes. These changes arise within the adipose tissue as well as inducing secondary detrimental effects on other organs like muscle and liver, including chronic low-grade inflammation mediated by adipocytokines (adipokine inflammation). This inflammation is modulated by dietary factors and nutrients including glucose and lipids, as well as gut bacteria in the form of endotoxin or LPS. The aim of this current review is to consider the impact of nutrients such as glucose and lipids on inflammatory pathways, specifically within adipose tissue. Furthermore, how nutrients such as these can influence adipokine inflammation and consequently insulin resistance directly through their effects on secretion of adipocytokines (TNFα, IL6 and resistin) as well as indirectly through increases in endotoxin is discussed.

The association of the triglyceride-to-HDL cholesterol ratio with insulin resistance in White European and South Asian men and women

INTRODUCTION

There is recent interest surrounding the use of the triglyceride-to-HDL cholesterol ratio as a surrogate marker of insulin resistance in clinical practice, as it may identify people at high risk of developing diabetes or its complications. However, it has been suggested using this lipid ratio may not be appropriate for measuring insulin resistance in African-Americans, particularly women. We investigated if this inconsistency extended to South Asian women in a UK multi-ethnic cohort of White Europeans and South Asians.

METHODS

Cross-sectional analysis was done of 729 participants from the ADDITION-Leicester study from 2005 to 2009. The association between tertiles of triglyceride-to-HDL cholesterol ratio to fasting insulin, homeostatic model of assessment for insulin resistance (HOMA1-IR), quantitative insulin sensitivity check index (QUICKI) and glucose: insulin ratio was examined with adjustment for confounding variables.

RESULTS

Incremental tertiles of the triglyceride-to-HDL cholesterol ratio demonstrated a significant positive association with levels of fasting insulin, HOMA1-IR, glucose: insulin ratio and a negative association with QUICKI in White European men (n = 255) and women (n = 250) and South Asian men (n = 124) (all p<0.05), but not South Asian women (n = 100). A significant interaction was demonstrated between sex and triglyceride-to-HDL cholesterol ratio tertiles in South Asians only (p<0.05). The area under the receiver operating characteristic curve for triglyceride-to-HDL cholesterol ratio to detect insulin resistance, defined as the cohort HOMA1-IR ≥ 75(th) percentile (3.08), was 0.74 (0.67 to 0.81), 0.72 (0.65 to 0.79), 0.75 (0.66 to 0.85) and 0.67 (0.56 to 0.78) in White European men and women, South Asian men and women respectively. The optimal cut-points for detecting insulin resistance were 0.9-1.7 in mmol/l (2.0-3.8 in mg/dl) for the triglyceride-to-HDL ratio.

CONCLUSION

In South Asian women the triglyceride-to-HDL cholesterol ratio was not associated with insulin resistance; therefore there may be limitations in its use as a surrogate marker in this group.

Triglyceride-based screening tests fail to recognize cardiometabolic disease in African immigrant and African-American men

BACKGROUND

The prevalence of cardiometabolic disease in Africa now rivals that of Western nations. Therefore, screening programs that lead to effective prevention of cardiometabolic disease in Africans is imperative. Most screening tests for cardiometabolic disease use triglyceride (TG) levels as a criterion. However, the failure rate of TG-based screening tests in African Americans is high. In Africans, the efficacy of TG-based screening tests is unknown. Our goal was to determine the association between hypertriglyceridemia (TG ≥150 mg/dL) and cardiometabolic disease in African and African-American men.

RESEARCH DESIGN AND METHODS

This was a cross-sectional study of 155 men (80 African immigrants, 75 African Americans) [age, 35±9 years, mean±standard deviation (SD), body mass index (BMI) 28.5±5.2 kg/m(2)] who self-identified as healthy. Lipid profiles were performed. Glucose tolerance and insulin resistance was determined by oral glucose tolerance tests (OGTT) and the insulin sensitivity index (S(I)), respectively. Cardiometabolic disease was defined by four possible subtypes--prediabetes, diabetes, insulin resistance, or metabolic triad [hyperinsulinemia, hyperapolipoprotein B, small low-density lipoprotein (LDL) particles].

RESULTS

TG levels were higher in men with cardiometabolic disease than without (88±43 versus 61±26 mg/dL, P<0.01). However, <10% of men with cardiometabolic disease had TG ≥150 mg/dL. Even within each cardiometabolic disease subtype, the prevalence of TG ≥150 mg/dL was <10%. Furthermore, TG levels in the 5% of men identified by OGTT as diabetic were ≤100 mg/dL (mean 71±24, range 45-100 mg/dL).

CONCLUSIONS

Hypertriglyceridemia is a poor marker of cardiometabolic disease in men of African descent. Therefore TG-based screening tests fail to identify both African immigrants and African-American men with cardiometabolic disease. As a consequence, the opportunity for early intervention and prevention is lost.

The tumor necrosis factor-α gene -238G>A polymorphism, dietary fat intake, obesity risk and serum lipid concentrations in black and white South African women

BACKGROUND/OBJECTIVES

This study explored interactions between dietary fat intake and the tumor necrosis factor-α gene (TNFA) -238G>A polymorphism (rs361525) on adiposity and serum lipid concentrations in apparently healthy premenopausal black and white South African (SA) women.

SUBJECTS/METHODS

Normal-weight (N=107) and obese (N=120) black, and normal-weight (N=89) and obese (N=62) white SA women underwent measurements of body composition, fasting lipids and dietary intake, and were genotyped for the -238G>A polymorphism.

RESULTS

Black women had a higher -238GA genotype frequency than white women (P<0.001), but there were no differences between body mass index groups. Black women with the -238A allele had a greater body fat % than those with the GG genotype (P<0.001). Further, in black women, with increasing polyunsaturated:saturated fat ratio and omega-6 (n-6):omega-3 (n-3) ratio, high-density lipoprotein-cholesterol (HDL-C) concentrations decreased, and total cholesterol (T-C):HDL-C ratio increased in those with the GA genotype but not the GG genotype. In addition, with increasing n-3 polyunsaturated fatty acid intake (percentage of total energy intake, %E), T-C:HDL-C ratio decreased in those with the GA genotype, but not in those with the GG genotype. In white SA women, with increasing eicosapentaenoic acid (%E) intake, low-density lipoprotein-cholesterol concentrations decreased in those with the GG genotype but not the GA genotype.

CONCLUSIONS

The -238G>A polymorphism was associated with body fatness in black women. Interactions between -238G>A genotypes and dietary fat intake on serum lipids and adiposity differed depending on dietary fat intake, but those for serum lipids were not the same in black and white SA women.

Fatty acid and very low density lipoprotein metabolism in obese African American and Caucasian women with type 2 diabetes

Type 2 diabetes mellitus (T2DM) is associated with increased plasma triglyceride (TG) concentrations, but African Americans (AA) have lower plasma TG than Caucasians (CC). We evaluated the hypothesis that obese AA women have lower plasma TG than obese CC women do because of differences in lipid kinetics. Eleven AA and 11 CC obese women with T2DM, matched on body mass index (BMI) (AA = 37 ± 1, CC = 37 ± 1 kg/m(2)), age, duration of diabetes, percentage body fat, and insulin sensitivity (S(I), determined by an intravenous glucose tolerance test), were studied. Plasma TG concentration (AA = 1.14 ± 0.11, CC = 1.88 ± 0.18 mmol/l), FFA rate of appearance (R(a)) into plasma (AA = 419 ± 27, CC = 503 ± 31 µmol·min(-1)), and total VLDL-TG secretion rate (AA = 18 ± 2, CC = 29 ± 4 µmol·min(-1)) were lower in AA than CC women (all P < 0.05). In contrast, plasma total apolipoprotein (apo)B-100 concentration (AA = 1,542 ± 179, CC = 1,620 ± 118 nmol/l) and VLDL-apoB-100 secretion rate (AA = 1.3 ± 0.1, CC = 1.3 ± 0.1 nmol·min(-1)) were similar in both groups, so the molar ratio of VLDL-TG secretion rate to VLDL-apoB-100 secretion rate was lower in AA women than in CC women. VLDL-TG concentration was lower in AA women due to lower total VLDL-TG secretion rate. However, the VLDL-apoB-100 secretion rate was the same in both groups, demonstrating that AA women secrete smaller VLDL particles containing less TG than do CC women.

The Metabolic Syndrome: How Definition Impacts the Prevalence and Risk in U.S. Adults: 1999-2004 NHANES

BACKGROUND

To examine the relationships various medical society definitions have on metabolic syndrome (MetS) prevalence and the likelihood of a MetS diagnosis among a national sample of the United States (US) adult population.

METHODS

The sample for this study included adults, 20 years and older, (N = 5620) who completed the mobile examination center (MEC) examination in the 1999-2004 National Health and Nutrition Examination Survey (NHANES). SUDAAN statistical software was used to estimate age-adjusted prevalence and odds ratios.

RESULTS

The overall age-adjusted MetS prevalence ranged from a high of 38.9% (ACE/AACE), to a low of 21.2% (EGIR). For most MetS definitions, males, people in the eighth decade of life (70-79 years of age), Mexican-Americans, those without a high school education, and those living in poverty were found to have the greatest prevalence. Additionally, females were 21% to 33% less likely to be diagnosed with the MetS. People in the seventh decade of life were two to four times more likely to have the MetS compared to those in the third decade of life. Furthermore, adults with greater than a high school education were 26% to 30% less likely to be diagnosed with the MetS and adults in the >/=400% poverty category were 24% to 29% less likely to be diagnosed with the MetS compared to those living below the 100% poverty demarcation.

CONCLUSION

MetS prevalence and the likelihood of being diagnosed with the MetS within populations are highly dependent on the requisite criteria and medical society definition used.

Determining cut-off values for neck circumference as a measure of the metabolic syndrome amongst a South African cohort: the SABPA study

The aim was to determine receiver operating characteristic (ROC) neck circumference (NC) cut offs best associated with the metabolic syndrome (MetS) in a South African cohort. We included 409 urban Africans and Caucasians and stratified them into gender and age groups (25-45 years; 45-65 years). Measurements included anthropometric, fasting overnight urine and biological markers for the MetS (systolic and diastolic blood pressure, glucose, triglycerides, and high density lipoprotein). ROC analysis determined pathological (NC) cut-points of 39 and 35 cm for young and older African men; 32 and 35 cm for young and old African women; 40 and 41 cm for Caucasian men; 34 and 33 cm for Caucasian women. Pathological NC cut-points significantly predicted MetS in all ethnic-gender-age groups except in African women (ORs 2.3-5.4; 95% CI 1.36-16.5). Multiple regression analyses revealed that MetS prevalence and ROC cut-points were not associated with renal impairment in any groups. ROC NC cut-points demonstrated that NC may be used as an additional anthropometric marker to predict the MetS in a South African cohort but not in African women.

Ethnic influences on the relations between abdominal subcutaneous and visceral adiposity, liver fat, and cardiometabolic risk profile: the International Study of Prediction of Intra-Abdominal Adiposity and Its Relationship With Cardiometabolic Risk/Intra-Abdominal Adiposity

BACKGROUND

Ethnic differences in cardiometabolic risk (CMR) may be related to patterns of ethnic-specific body fat distribution.

OBJECTIVE

We aimed to identify differences across ethnic groups in interrelations between BMI, abdominal adiposity, liver fat, and CMR profile.

DESIGN

In the International Study of Prediction of Intra-Abdominal Adiposity and Its Relationship With Cardiometabolic Risk/Intra-Abdominal Adiposity, 297 physicians recruited 4504 patients (from 29 countries). In the current cross-sectional analyses, 2011 whites, 166 African Caribbean blacks, 381 Hispanics, 1192 East Asians, and 347 Southeast Asians were included. Computed tomography was used to assess abdominal fat distribution and to estimate liver fat content. Anthropometric variables and CMR profile were measured.

RESULTS

Higher ranges of BMI were associated with higher levels of visceral [visceral adipose tissue (VAT)] and deep subcutaneous [deep subcutaneous adipose tissue (DSAT)] adiposity, with significant ethnic differences regarding the slope of these relations. Despite lower absolute BMI values, East Asians presented the largest accumulation of VAT but the lowest accumulation of DSAT with increasing adiposity. The association of BMI with liver fat did not differ between ethnic groups. Liver fat and DSAT were positively correlated with VAT with no ethnic variation. All ethnic groups had a similar association between a 1-SD increase in VAT, DSAT, or liver fat with hypertension, type 2 diabetes, hypertriglyceridemia, low HDL-cholesterol concentration, or high C-reactive protein concentration.

CONCLUSIONS

Ethnicity significantly affects abdominal adiposity and liver fat partitioning, and East Asians have the most deleterious abdominal fat distribution. Irrespective of ethnicity, abdominal and hepatic fat depots are strongly interrelated and increased with obesity. Higher amounts of VAT or liver fat are associated with a more deteriorated CMR profile in all ethnic groups.

Insulin resistance status and four-year changes in other cardiometabolic risk factors in West-African adults: the Benin study

BACKGROUND

The association of insulin resistance (IR) with other cardiometabolic risk (CMR) factors in sub-Saharan Africans is poorly documented. This study examined the links between IR and the evolution of blood pressure (BP), glycaemia, serum lipids and abdominal obesity in the population of Benin.

DESIGN

Population-based longitudinal study.

METHODS

This study initially included 541 apparently healthy Beninese adults (50% women) aged 25-60 years who were randomly selected in a large city, a small town and a rural area. After a baseline survey, our subjects were followed up after 2 years, and again at 4 years. IR based on homeostasis model assessment (HOMA), blood glucose, BP, waist circumference (WC), triglycerides, total cholesterol and HDL-cholesterol were measured. Complete data at the end of the follow-up periods was available for 416 subjects.

RESULTS

IR was more prevalent in women than in men (33.2% versus 17.8%) and it was generally associated with more adverse values of CMR factors, excepting BP. In controlling for baseline age, sex, WC, diet, lifestyle variables and WC changes; the relative risk (RR) of hyperglycemia over 4 years was as least 3-fold in IR subjects, compared to normal subjects. The RR of abdominal obesity was 5.3 (1.04-26.93) in IR women, compared to non-IR. The association of IR with the evolution of dyslipidemia was inconsistent, but IR tended to exacerbate low HDL-cholesterol.

CONCLUSION

Over 4 years, IR exacerbated hyperglycemia in both men and women, and abdominal obesity in women, but IR did not affect blood pressure. Further research on the link found between IR and dyslipidemia, particularly low HDL-C, is needed in sub-Saharan Africa.

Health disparities in endocrine disorders: biological, clinical, and nonclinical factors--an Endocrine Society scientific statement

OBJECTIVE

The aim was to provide a scholarly review of the published literature on biological, clinical, and nonclinical contributors to race/ethnic and sex disparities in endocrine disorders and to identify current gaps in knowledge as a focus for future research needs. PARTICIPANTS IN DEVELOPMENT OF SCIENTIFIC STATEMENT: The Endocrine Society's Scientific Statement Task Force (SSTF) selected the leader of the statement development group (S.H.G.). She selected an eight-member writing group with expertise in endocrinology and health disparities, which was approved by the Society. All discussions regarding the scientific statement content occurred via teleconference or written correspondence. No funding was provided to any expert or peer reviewer, and all participants volunteered their time to prepare this Scientific Statement.

EVIDENCE

The primary sources of data on global disease prevalence are from the World Health Organization. A comprehensive literature search of PubMed identified U.S. population-based studies. Search strategies combining Medical Subject Headings terms and keyword terms and phrases defined two concepts: 1) racial, ethnic, and sex differences including specific populations; and 2) the specific endocrine disorder or condition. The search identified systematic reviews, meta-analyses, large cohort and population-based studies, and original studies focusing on the prevalence and determinants of disparities in endocrine disorders. consensus process: The writing group focused on population differences in the highly prevalent endocrine diseases of type 2 diabetes mellitus and related conditions (prediabetes and diabetic complications), gestational diabetes, metabolic syndrome with a focus on obesity and dyslipidemia, thyroid disorders, osteoporosis, and vitamin D deficiency. Authors reviewed and synthesized evidence in their areas of expertise. The final statement incorporated responses to several levels of review: 1) comments of the SSTF and the Advocacy and Public Outreach Core Committee; and 2) suggestions offered by the Council and members of The Endocrine Society.

CONCLUSIONS

Several themes emerged in the statement, including a need for basic science, population-based, translational and health services studies to explore underlying mechanisms contributing to endocrine health disparities. Compared to non-Hispanic whites, non-Hispanic blacks have worse outcomes and higher mortality from certain disorders despite having a lower (e.g. macrovascular complications of diabetes mellitus and osteoporotic fractures) or similar (e.g. thyroid cancer) incidence of these disorders. Obesity is an important contributor to diabetes risk in minority populations and to sex disparities in thyroid cancer, suggesting that population interventions targeting weight loss may favorably impact a number of endocrine disorders. There are important implications regarding the definition of obesity in different race/ethnic groups, including potential underestimation of disease risk in Asian-Americans and overestimation in non-Hispanic black women. Ethnic-specific cut-points for central obesity should be determined so that clinicians can adequately assess metabolic risk. There is little evidence that genetic differences contribute significantly to race/ethnic disparities in the endocrine disorders examined. Multilevel interventions have reduced disparities in diabetes care, and these successes can be modeled to design similar interventions for other endocrine diseases.

Waist circumference in children and adolescents correlate with metabolic syndrome and fat deposits in young adults

BACKGROUND & AIMS

To determine the relevance of waist circumference (WC) measurement and monitoring in children and adolescents as an early indicator of overweight, metabolic syndrome (MS) and cardiovascular problems in young adults in comparison with visceral and subcutaneous adiposity.

METHODS

A cohort study with 159 subjects (51.6% female) started in 1999 with an average age of 13.2 years. In 1999, 2006 and 2008 weight, height, and WC were evaluated. In 2006 blood samples for laboratory diagnosis of MS were added. In 2008 abdominal computed tomography (ACT) to quantify the fat deposits were also added.

RESULTS

The WC measured in children and adolescents was strongly correlated with body mass index (BMI) measured simultaneously. A strong correlation was established between WC in 1999 with measures of WC and BMI as young adults. WC strongly correlated with fat deposits in ACT. The WC in 1999 expressed more subcutaneous fat (SAT), while the WC when young adults expressed strong correlation with both visceral fat (VAT) and SAT. The correlation of WC with fat deposits was stronger in females. WC and not BMI in 1999 was significantly higher in the group that evolved to MS.

CONCLUSIONS

The WC in children and adolescents was useful in screening patients for MS. WC expressed the accumulation of abdominal fat; especially subcutaneous fat.

Prevalence and clinical correlates of metabolic syndrome in Nigerians living with human immunodeficiency virus/acquired immunodeficiency syndrome

BACKGROUND

Sub-Saharan Africa bears an inordinate burden of human immunodeficiency virus (HIV) infection/acquired immune deficiency syndrome (AIDS). Reports have shown increased prevalence of clustering of cardiovascular risk factors referred to as metabolic syndrome in treatment-naïve patients and patients on highly active antiretroviral therapy (HAART). In view of the fact that metabolic syndrome is a heterogeneous disorder with substantial variability in the prevalence and component traits within and across populations and the dearth of publications on the prevalence and clinical correlates of metabolic syndrome in people living with HIV/AIDS (PLWHA) in Nigeria, this study was carried out to determine the prevalence and clinical correlates of metabolic syndrome among an HIV-infected outpatient population using the National Cholesterol Education Adult Treatment Panel III (NCEP ATP III), the International Diabetes Federation (IDF), and the Joint Interim Statement (JIS) definitions. We also sought to determine if HAART use and CD4 count level were associated with metabolic syndrome.

METHODS

This cross-sectional study involved 291 (95 men, 196 women) consecutive PLWHA. Anthropometry, blood pressure, fasting plasma glucose, and lipid profile values were determined.

RESULTS

The prevalence rates of metabolic syndrome according to the ATP III, IDF, and JIS criteria were 12.7%, 17.2%, and 21.0%, respectively. Metabolic syndrome was significantly associated with female gender (all definitions), body mass index (all definitions), increasing age, and CD4 count (IDF definition). There was no significant association between metabolic syndrome and HAART. The concordance [kappa coefficient (κ)] between the definitions of metabolic syndrome varied between 0.583 and 0.878.

CONCLUSIONS

The prevalence of metabolic syndrome varied with the criteria used and metabolic syndrome correlates with traditional cardiovascular risk factors rather than HAART-related factors.

Biogeographic ancestry, self-identified race, and admixture-phenotype associations in the Heart SCORE Study

Large epidemiologic studies examining differences in cardiovascular disease (CVD) risk factor profiles between European Americans and African Americans have exclusively used self-identified race (SIR) to classify individuals. Recent genetic epidemiology studies of some CVD risk factors have suggested that biogeographic ancestry (BGA) may be a better predictor of CVD risk than SIR. This hypothesis was investigated in 464 African Americans and 771 European Americans enrolled in the Heart Strategies Concentrating on Risk Evaluation (Heart SCORE) Study in March and April 2010. Individual West African and European BGA were ascertained by means of a panel of 1,595 genetic ancestry informative markers. Individual BGA varied significantly among African Americans and to a lesser extent among European Americans. In the total cohort, BGA was not found to be a better predictor of CVD risk factors than SIR. Both measures predicted differences in the presence of the metabolic syndrome, waist circumference, triglycerides, body mass index, very low density lipoprotein cholesterol, lipoprotein A, and systolic and diastolic blood pressure between European Americans and African Americans. These results suggest that for most nongenetic cardiovascular epidemiology studies, SIR is sufficient for predicting CVD risk factor differences between European Americans and African Americans. However, higher body mass index and diastolic blood pressure were significantly associated with West African BGA among African Americans, suggesting that BGA should be considered in genetic cardiovascular epidemiology studies carried out among African Americans.

Sex differences in human adipose tissues - the biology of pear shape

Women have more body fat than men, but in contrast to the deleterious metabolic consequences of the central obesity typical of men, the pear-shaped body fat distribution of many women is associated with lower cardiometabolic risk. To understand the mechanisms regulating adiposity and adipose tissue distribution in men and women, significant research attention has focused on comparing adipocyte morphological and metabolic properties, as well as the capacity of preadipocytes derived from different depots for proliferation and differentiation. Available evidence points to possible intrinsic, cell autonomous differences in preadipocytes and adipocytes, as well as modulatory roles for sex steroids, the microenvironment within each adipose tissue, and developmental factors. Gluteal-femoral adipose tissues of women may simply provide a safe lipid reservoir for excess energy, or they may directly regulate systemic metabolism via release of metabolic products or adipokines. We provide a brief overview of the relationship of fat distribution to metabolic health in men and women, and then focus on mechanisms underlying sex differences in adipose tissue biology.

Visceral adiposity as a target for the management of the metabolic syndrome

Atherosclerosis, the underlying cause of atherosclerotic cardiovascular disease (ACVD), develops due not only to a single cardiovascular risk factor but to a variety of complex factors. The concept of the multiple cardiometabolic risk factor clustering syndrome has been proposed as a highly atherogenic state, independent of hypercholesterolemia and smoking. Body fat distribution, especially visceral fat accumulation, is a major correlate of a cluster of diabetogenic, atherogenic, prothrombotic, and proinflammatory metabolic abnormalities referred to as the metabolic syndrome, with dysfunctional adipocytes and dysregulated production of adipocytokines (hypoadiponectinemia). Medical research has focused on visceral adiposity as an important component of the syndrome in Japanese subjects with a mild degree of adiposity compared with Western subjects. For the prevention of ACVD at least in Japan, it might be practical to stratify subjects with multiple risk factors for atherosclerotic cardiovascular disease based on visceral fat accumulation. Visceral fat reduction through health promotion programs using risk factor-oriented approaches may be effective in reducing ACVD events, as well as producing improvement in risks and hypoadiponectinemia. This review article discusses visceral adiposity as a key player in the syndrome. Visceral fat reduction with life-style modification is a potentially useful strategy in the prevention of ACVD in patients with the metabolic syndrome.

Insulin resistance and adipose-derived hormones in young men with untreated obstructive sleep apnea

PURPOSE

Obstructive sleep apnea (OSA) increases the risk for insulin resistance (IR). The mechanisms that link the two are not clear and are frequently confounded by obesity. OSA is associated with alterations in adipose-derived hormones (adipokines) that increase IR; however, previous studies have focused on middle-aged and older adults. The objective of this study was to determine if IR and alterations in adipokines exist in young men with OSA, independent of obesity.

METHODS

Subjects were assigned into the following groups based on body mass index and presence of OSA: obese with OSA (OSA, n = 12), obese without OSA (NOSA, n = 18), and normal weight without OSA (CON, n = 15). Fasting blood was obtained for batch analysis of biomarkers of IR. The homeostasis model assessment (HOMA) method was used to assess IR.

RESULTS

HOMA and leptin were higher in the OSA group than the CON group. There were no differences in insulin, tumor necrosis factor alpha (TNF-α), and interleukin-6 (IL-6) between the OSA and NOSA groups. Adiponectin was lower in the OSA group vs. NOSA and CON; however, when controlled for central abdominal fat (CAF), the difference was nullified. When controlled for total body adiposity, however, CAF was 24 % higher in the subjects with OSA vs. subjects without OSA.

CONCLUSIONS

These findings suggest that excess CAF in young men with OSA may contribute to risk for type 2 diabetes indirectly by a degree that would otherwise not be reached through obesity, although further research is needed.

Comparability of skinfold thickness to DXA whole-body total fat in their associations with serum triglycerides in youths

OBJECTIVE

To determine the comparability of triceps and subscapular skinfold thicknesses with dual X-ray absorptiometry (DXA) whole-body total fat (kg) in relation to serum triglyceride (TG) levels and increased risk of elevated TG levels, and identified optimum skinfold cutoffs for screening purposes in US adolescents.

SUBJECTS/METHODS

Data from triceps and subscapular skinfold thickness, DXA whole-body total fat and serum TGs were obtained from 1505 US adolescents ages 12.00-17.99 years, who participated in two continuous National Health and Nutrition Examination Survey (NHANES) cycles 2001-2004. Study associations were examined with linear and logistic models, and ROC (receiver operating characteristic) analyses were used to derive skinfold cutoffs for identifying the risk of elevated TG levels.

RESULTS

Using area under the curves (AUCs) as metrics of prediction accuracy (with bootstrapped 95% CIs), no significant differences were found between skinfolds and DXA logistic models for predicting elevated TG levels. Similarly, skinfold and DXA models had comparable precision in predicting continuous serum TG from bootstrapped root mean squared errors for both sexes. Population-adjusted marginal mean estimates indicated that youths whose skinfolds are in the top quartile had TG levels within 83-108 mg/dl. Skinfold cutoffs for predicting elevated estimated TG using ROC analyses showed that cutoffs decreased with age and ranged from 13 to 30 mm for ages 12-17, in yearly intervals.

CONCLUSION

Skinfold thicknesses were comparable to DXA whole-body total fat in predicting serum TG levels. These skinfold cutoffs could be used in practical settings as a first pass screener for identifying US adolescents at risk of elevated serum TGs.

The triglyceride paradox in people of African descent

Even though insulin resistance, cardiovascular disease (CVD), and type 2 diabetes (T2D) are associated with hypertriglyceridemia, blacks with these conditions usually have normal triglyceride (TG) levels. This is often called a lipid paradox. More precisely, it is a "TG paradox." The pathways that lead to hypertriglyceridemia have been intensively explored. Yet, the pathways that allow TG levels to be normal in the presence of insulin resistance have received little attention and this is problematic. Tests designed for the early detection of insulin-resistant conditions often use elevated TG levels as a diagnostic criterion. However, insulin resistance, CVD, and T2D are not usually associated with hypertriglyceridemia in people of African descent; therefore, the widespread use of TG levels to predict these conditions needs re-evaluation. This review focuses on black-white differences in: (1) the lipid profile across North America, Europe, and Africa; (2) the efficacy of TG-based screening tests, specifically the metabolic syndrome and its two abbreviated versions, the hypertriglycerdemic waist and TG/high-density lipoprotein cholesterol (HDL-C) ratio; and (3) the mechanisms that allow TG to be normal even in the presence of insulin resistance. Overall, a broader understanding of how TG physiology varies by race could lead to better diagnostic tests and improved health outcomes.

The Association between Self-Reported Energy Intake and Intra-Abdominal Adipose Tissue in Perimenopausal Women

We have previously shown that physical activity predicts intra-abdominal adipose tissue (IAT), but it is unknown whether energy intake predicts IAT independently of physical activity in a community-based, naturalistic environment. The association of energy intake with IAT was explored cross-sectionally in women, recruited between 2002 and 2005 for a study of fat patterning in midlife. IAT at L(4)-L(5) vertebral interspace was assessed by computed tomography, energy intake by the Block Food Frequency Questionnaire, and physical activity by the Kaiser Physical Activity Survey. Linear regression models were used for the principal analyses. Among the 257 women, 48% were African American and 52% were Caucasian. Women were 52 ± 3 years old, and 49% were postmenopausal. Every 500 kcal increase in energy intake was associated with a 6% higher IAT (P = 0.02), independent of physical activity (P = 0.02), after adjustment for ethnicity, menopausal status, age, smoking, income, and DXA-assessed percent body fat. Energy intake had a significant interaction with ethnicity (P = 0.02), but not with physical activity. Models using the IAT to subcutaneous abdominal adipose tissue ratio as an outcome had similar associations. In conclusion, self-reported EI was associated with preferential IAT accumulation in midlife women, independent of physical activity. This association was significantly stronger in Caucasian than African American women. Future longitudinal studies are needed to explore lifestyle predictors of IAT accumulation during the menopausal transition.

Effects of aerobic vs. resistance training on visceral and liver fat stores, liver enzymes, and insulin resistance by HOMA in overweight adults from STRRIDE AT/RT

While the benefits of exercise are clear, many unresolved issues surround the optimal exercise prescription. Many organizations recommend aerobic training (AT) and resistance training (RT), yet few studies have compared their effects alone or in combination. The purpose of this study, part of Studies Targeting Risk Reduction Interventions Through Defined Exercise-Aerobic Training and/or Resistance Training (STRRIDE/AT/RT), was to compare the effects of AT, RT, and the full combination (AT/RT) on central ectopic fat, liver enzymes, and fasting insulin resistance [homeostatic model assessment (HOMA)]. In a randomized trial, 249 subjects [18-70 yr old, overweight, sedentary, with moderate dyslipidemia (LDL cholesterol 130-190 mg/dl or HDL cholesterol ≤ 40 mg/dl for men or ≤ 45 mg/dl for women)] performed an initial 4-mo run-in period. Of these, 196 finished the run-in and were randomized into one of the following 8-mo exercise-training groups: 1) RT, which comprised 3 days/wk, 8 exercises, 3 sets/exercise, 8-12 repetitions/set, 2) AT, which was equivalent to ∼19.2 km/wk (12 miles/wk) at 75% peak O(2) uptake, and 3) full AT + full RT (AT/RT), with 155 subjects completing the intervention. The primary outcome variables were as follows: visceral and liver fat via CT, plasma liver enzymes, and HOMA. AT led to significant reductions in liver fat, visceral fat, alanine aminotransferase, HOMA, and total and subcutaneous abdominal fat (all P < 0.05). RT resulted in a decrease in subcutaneous abdominal fat (P < 0.05) but did not significantly improve the other variables. AT was more effective than RT at improving visceral fat, liver-to-spleen ratio, and total abdominal fat (all P < 0.05) and trended toward a greater reduction in liver fat score (P < 0.10). The effects of AT/RT were statistically indistinguishable from the effects of AT. These data show that, for overweight and obese individuals who want to reduce measures of visceral fat and fatty liver infiltration and improve HOMA and alanine aminotransferase, a moderate amount of aerobic exercise is the most time-efficient and effective exercise mode.

Fatty liver, abdominal visceral fat, and cardiometabolic risk factors: the Jackson Heart Study

OBJECTIVE

The goal of this study was to examine whether fatty liver and abdominal visceral adipose tissue (VAT) are jointly associated with cardiometabolic abnormalities.

METHODS AND RESULTS

Black participants were from the Jackson Heart Study (n=2882, 65% women) who underwent computed tomography. Fatty liver was measured by liver attenuation in Hounsfield units (LA), and VAT was quantified volumetrically. Cross-sectional associations between LA, VAT, and cardiometabolic risk factors were assessed using linear and logistic regression, and their joint associations were further examined in 4 subgroups: high-LA/low-VAT (n=1704), low-LA/low-VAT (n=422), high-LA/high-VAT (n=436), and low-LA/high-VAT (n=320). Both LA and VAT were associated with most cardiometabolic traits (all P<0.0001), which persisted after additional adjustment for each other (LA, P<0.01-0.0001; VAT, P<0.0001). In bootstrap analyses, the regression coefficient of VAT was significantly greater than LA for triglycerides, high-density lipoprotein cholesterol, impaired glucose, and metabolic syndrome (P=0.009-0.0001). The interaction between LA and VAT was significant for high-density lipoprotein cholesterol (P=0.002), impaired glucose (P=0.003), and metabolic syndrome (P=0.04). Among 4 subgroups, participants with higher VAT and lower LA had higher prevalence of cardiometabolic traits than those with each condition alone.

CONCLUSION

Both fatty liver and VAT are independent correlates of cardiometabolic risk, but the associations are stronger for VAT than for fatty liver.

Comparing abilities of different lipid measures in diagnosis of insulin resistance: a Survey of Risk Factors of Non-Communicable Diseases (SuRFNCD-2007) study

BACKGROUND

Dyslipidemia is a distinguishing characteristic of subjects with insulin resistance. Our aim was to determine the predictive abilities and appropriate cutoffs of different lipid variables for insulin resistance.

METHODS

We used the data of the individuals without history of known diabetes mellitus, aged 25-64 years, from the third national Survey of Risk Factors of Non-Communicable Diseases (SuRFNCD-2007). Fasting blood was collected for lipids, glucose and insulin. Receiver operating characteristics (ROC) curves were used to evaluate the predictive abilities of lipid measures for insulin resistance reflected by a homeostasis model assessment value >1.775. The optimal cutoffs of the selected measures were determined using the maximum Youden index and the point closest to (0,1) on the ROC curve, and were compared with metabolic syndrome definitions to diagnose hyperinsulinemia (fasting insulin ≥10 in men and ≥11 U/L in women).

RESULTS

Among lipid measures, low-density lipoprotein cholesterol (LDL-C) was the most tenuously related parameter to insulin resistance. On the contrary, triglycerides and triglycerides to high-density lipoprotein cholesterol ratio (triglycerides/HDL-C) had the highest abilities to determine insulin resistance, regardless of sex and body mass index (BMI). The optimal triglycerides and triglycerides/HDL-C cutoffs were 145 mg/dL and 3.75 for men and 109 mg/dL and 3.00 for women, respectively, which had similar abilities to metabolic syndrome definitions in identifying hyperinsulinemia.

CONCLUSION

Among lipid measures, triglycerides and the triglycerides/HDL-C ratio have the highest predictive abilities for insulin resistance, and the diagnostic values of their appropriate cutoffs are similar to those of metabolic syndrome definitions.

Differential effect of gender on hepatic fat

BACKGROUND

There are discrepant data on whether men or women have a higher risk for hepatic steatosis.

OBJECTIVE

To examine the influence of gender on hepatic adiposity in teenagers and young adults.

MATERIALS AND METHODS

We measured subcutaneous abdominal fat (SAF), intra-abdominal fat (IAF) and hepatic tissue density (a surrogate measure of hepatic fat) using CT in 505 healthy teenagers and young adults (254 males, 251 females; ages 15-22.9 years).

RESULTS

Overall, compared to men, women had higher values of SAF (P < 0.0001) but similar measures of IAF and liver tissue density (P = 0.09 and 0.92, respectively). However, when compared to overweight/obese men, overweight/obese women had strikingly similar IAF values (P = 0.85) but lower hepatic fat (P = 0.009). Multiple regression analyses indicated that, after adjusting for age and SAF, IAF independently predicted hepatic density in males (P < 0.0001) but not in females (P = 0.36). Hepatic fat increased with body mass in males from lean to overweight and obese (P < 0.0001) but not in females (P > 0.05).

CONCLUSION

When compared to overweight and obese young women, overweight and obese young men are at greater risk for hepatic steatosis, independent of IAF.

Bioactive androgens and glucuronidated androgen metabolites are associated with subcutaneous and ectopic skeletal muscle adiposity among older black men

Aging is associated with declining serum levels of androgenic hormones and with increased skeletal muscle fat infiltration, an emerging risk factor for type 2 diabetes mellitus (T2DM). Androgens regulate fat mass and glucose homeostasis, but the effect of androgenic hormones on skeletal muscle fat infiltration is largely unknown. Thus, the aim of the current study was to examine the association of serum androgens and their precursors and metabolites with skeletal muscle fat infiltration and T2DM in a black male population group at high risk of T2DM. Serum androgens, estrogens, and androgen precursors and metabolites were measured using mass spectrometry; and calf skeletal muscle fat distribution (subcutaneous and intermuscular fat; skeletal muscle density) was measured using quantitative computed tomography in 472 Afro-Caribbean men 65 years and older. Bioactive androgens, testosterone, free testosterone, and dihydrotestosterone were associated with less skeletal muscle fat infiltration (r = -0.14 to -0.18, P < .05) and increased skeletal muscle density (r = 0.10 to 0.14, P < .05), independent of total adiposity. In addition, glucuronidated androgen metabolites were associated with less subcutaneous fat (r = -0.11 to -0.15, P < .05). Multivariate logistic regression analysis identified an increased level of 3α-diol-3 glucuronide (odds ratio = 1.38, P < .01) and a decreased level of dihydrotestosterone (odds ratio = 0.66, P < .01) to be significantly associated with T2DM. Our findings suggest that, in elderly black men, independent of total adiposity, bioactive androgens and glucuronidated androgen metabolites may play previously unrecognized role in skeletal muscle fat distribution. Longitudinal studies are needed to further evaluate the relationship between androgens and androgen metabolites with changes in skeletal muscle fat distribution with aging and the incidence of T2DM.