Relation of leptin to insulin resistance syndrome in children

OBJECTIVES: To examine the relation of leptin to insulin resistance, as measured by euglycemic insulin clamp, and insulin resistance syndrome factors in thin and heavy children. RESEARCH METHODS AND PROCEDURES: Anthropometrics, insulin, blood pressure, and leptin were measured in 342 11- to 14-year-old children (189 boys, 153 girls, 272 white, 70 black). Insulin sensitivity (M) was determined by milligrams glucose uptake per kilogram per minute and expressed as M/lean body mass (Mlbm). Children were divided by median BMI (boys = 20.5 kg/m(2); girls = 21.4 kg/m(2)) into below-median (thin) and above-median (heavy) groups. Correlation coefficients between log-leptin and components of insulin resistance syndrome were adjusted for Tanner stage, gender, and race. RESULTS: BMI was related to leptin in boys (r = 0.70, p < 0.001) and girls (r = 0.75, p < 0.001). Leptin was higher in girls than boys (32.6 vs. 12.3 ng/mL, p = 0.0001). Leptin levels increased in girls and decreased in boys during puberty, paralleling the changes in body fat. Leptin was significantly correlated with insulin, Mlbm, triglycerides, and blood pressure in heavy children and only with insulin in thin children. After adjustment for body fat, the correlations remained significant for insulin and Mlbm in heavy children and with insulin in thin children. DISCUSSION: Significant associations were found between leptin and insulin resistance in children, and these associations were attenuated by adjustment for adiposity. These findings at age 13 likely have long-term consequences in the development of the obesity-insulin resistance-related cardiovascular risk profile.     

Presence of the Metabolic Syndrome in Obese Adolescents Predicts Impaired Glucose Tolerance and Nonalcoholic Fatty Liver Disease

PURPOSE: To evaluate whether the presence of metabolic syndrome (MS) in obese adolescents is associated with other comorbidities of obesity METHODS: A total of 85 obese teens (70% female and 30% male) with fasting insulin >25 microU/ml and family history of type 2 diabetes mellitus and/or acanthosis nigricans were studied. Mean age was 15.8 +/- 1.7 years and body mass index (BMI) was 39.3 +/- 6.6 kg/m(2). Of the subjects, 54% were Hispanic and 35% black, 5% white, 5% American Indian, and 1% Asian. Laboratory analysis included fasting lipids, glucose, gamma-glutamyl transpeptidase (GGT), and oral glucose tolerance testing. Additional liver transaminase levels were determined and liver ultrasound (US) was performed to evaluate the presence and severity of fatty liver. RESULTS: All subjects met MS criteria for children for waist circumference, 49% for blood pressure, 54% for high-density lipoprotein, 54% for triglycerides, and 20% for impaired fasting glucose (IFG) or impaired glucose tolerance [IGT]). In all, 47 subjects had three or more MS criteria. BMI was no different between groups with and without MS. Subjects with three or more MS criteria were more likely to have IGT (p = .004), elevated alanine aminotransferase (p = .039), elevated GGT (p = .036), fatty liver on US (p < .001), and more severe fatty liver (p = .001). CONCLUSIONS: Abnormal glucose regulation and evidence of nonalcoholic fatty liver disease (NAFLD) were more common in subjects meeting three criteria for MS than in those meeting fewer criteria. The identification of MS provides value to the primary care provider. Those patients meeting criteria for MS should be evaluated for glucose intolerance and NAFLD.     

Lower serum adiponectin levels in African-American boys

OBJECTIVE: To examine adiponectin, an adipocyte-secreted hormone with anti-inflammatory and insulin-sensitizing effects, in relation to race or gender in younger subjects. RESEARCH METHODS AND PROCEDURES: The relationship of adiponectin, quantitated by radioimmunoassay, to anthropometric and metabolic factors (fasting insulin, glucose, and leptin) and reproductive hormones was examined in 46 healthy African Americans (25 girls/21 boys) and 40 whites (20 girls/20 boys) ranging in age from 12 to 21 years. RESULTS: There was no statistical difference in BMI or in BMI percentile among the four groups. Sums of skinfolds, but not skinfold percentile, were significantly lower in boys than girls (p = 0.001 and p = 0.896, respectively), whereas there was no difference between racial groups. Leptin was significantly greater in girls (p = 0.0002). There was no difference in fasting serum glucose, insulin, or homeostasis model assessment score among any of the groups. There was a significant negative univariate relationship between serum adiponectin and both BMI and BMI percentile for the entire group (p = 0.006 and p = 0.005). In a multivariate model, BMI percentile (p = 0.005) and the interaction between race and gender (p = 0.026) were significant predictors of serum adiponectin. In this model, African-American boys had the lowest serum adiponectin level, 37% less than white boys, who had the highest adiponectin levels. DISCUSSION: Serum adiponectin levels are reduced in young obese subjects (African Americans and whites) and are lower in African-American boys than white boys. A lower adiponectin level in African-American boys may predispose this group to a greater risk of diabetes and cardiovascular disease.     

Ten-year change in serum uric acid and its relation to changes in other metabolic risk factors in young black and white adults: the CARDIA study

Elevated serum uric acid is commonly seen in association with obesity, glucose intolerance, hypertension and dyslipidemia. There is currently no satisfactory explanation for the relation of uric acid and the metabolic syndrome (MetSyn). This study aimed to evaluate the relations of change in serum uric acid with changes in components of the MetSyn in young adults. We studied 1,249 male and 1,362 female black and white subjects aged 17–35 years (baseline) from the Coronary Artery Risk Development in Young Adults (CARDIA) Study, which attended a 10-year follow-up. Metabolic factors assessed at both time periods included BMI, waist circumference, blood pressure, fasting glucose, insulin, and lipids. Confounders examined (baseline and change variables) were serum creatinine, alcohol, smoking, physical activity, and oral contraceptives. Mean uric acid increased the most in black males (+0.5 mg/dl), followed by white males (+0.3 mg/dl) and black females (+0.2 mg/dl) (all P < 0.01), with the least change among white females (+0.1 mg/dl) (ns). Although change in all of the metabolic factors was associated with change in uric acid in the anticipated directions, in multivariable analyses only BMI and triglycerides had a significant independent association with uric acid in all race-sex-groups. Among confounders, only change in serum creatinine showed a strong independent association with uric acid. In conclusion, besides weight gain and renal excretion, increasing uric acid concentrations in young adults are strongly related to corresponding changes in triglycerides. The correlation of uric acid and triglycerides was found within the normal range and could not be explained by obesity.     

Analysis of obesity and hyperinsulinemia in the development of metabolic syndrome: San Antonio Heart Study

OBJECTIVE: To use standardized cut-offs of body mass index (BMI), waist circumference, waist-to-hip ratio, and fasting insulin levels to predict the development of metabolic disorders and metabolic syndrome. RESEARCH METHODS AND PROCEDURES: We performed an 8-year follow-up study of 628 non-Hispanic whites and 1340 Mexican Americans, ages 25 to 64 years, from the second cohort of the San Antonio Heart Study. We defined metabolic disorders as dyslipidemia (triglycerides > or =2.26 mM or high-density lipoprotein <0.91 mM in men and <1.17 mM in women), hypertension (blood pressure > or =140 or >=90 mm Hg, or receiving antihypertensive medications), and type 2 diabetes (fasting glucose > or =7.0 mM, 2-hour test glucose > or =11.1 mM, or receiving anti-diabetic medications). People with at least two metabolic disorders were defined as having metabolic syndrome. RESULTS: High waist-to-hip ratio and fasting insulin levels were significant predictors of developing metabolic syndrome. High anthropometric indices remained significant predictors of metabolic syndrome after adjusting for fasting insulin. Waist circumference, BMI, and insulin had similar areas under the receiver operating characteristic curves (0.74 to 0.76). Further multivariate analyses combining these indices showed minimal increase in prediction. Of subjects who had a combination of high BMI (> or =30 kg/m(2)) and high waist circumference (above "Action Level 2"), 32% developed metabolic syndrome, compared with 10% of subjects with both low BMI and low waist circumference. DISCUSSION: These findings support the National Institutes of Health recommendations for reducing the risk of metabolic syndrome. Adjustment for baseline fasting insulin levels had only a small effect on the ability of anthropometric indices to predict the metabolic syndrome.     

Obesity,fasting plasma insulin,and C-reactive protein levels in healthy children

OBJECTIVE: Obesity is associated with hyperinsulinemia and increased level of C-reactive protein in older children and adults, but little is known about these relationships in very young children. We examined these relationships in healthy 2- to 3-year-old children. RESEARCH METHODS AND PROCEDURES: Analyses were performed on data from 491 healthy 2- to 3-year-old Hispanic children enrolled in a dietary study conducted in New York City, 1992 to 1995. RESULTS: Body mass index (BMI), ponderal index, and sum of four skinfolds were highly correlated (r > 0.75) in both boys and girls. Fasting insulin and glucose levels were only modestly correlated (r = 0.37 for boys and r = 0.28 for girls; p < 0.001 for both), but essentially all of the variability in a calculated index of insulin resistance was attributable to variability in fasting insulin level. The correlations of BMI with fasting insulin level were r = 0.16 (p < 0.05) in boys and r = 0.14 (p < 0.05) in girls. In separate multivariate regression analyses adjusting for age and sex, BMI and ponderal index were associated with fasting plasma insulin level (p < 0.001 for both obesity measures). In multivariate regression analyses adjusting simultaneously for age, sex, and either BMI or ponderal index, fasting insulin level, but not these obesity measures, was associated with C-reactive protein level. DISCUSSION: Obesity is associated with higher fasting insulin level, and fasting insulin is associated with C-reactive protein level, in healthy 2- to 3-year-old children.     

Associations between the metabolic syndrome and its components, watching television and physical activity

OBJECTIVE: To examine the associations between watching television and physical activity with the metabolic syndrome and its components. STUDY DESIGN: Cross-sectional study. METHODS: This study was conducted among 358 subjects recruited from the Department of Health Management of Chang Gung Medical Centre in Linkou. After adjustment for gender, age and body mass index (BMI), the odds ratios (ORs) of the metabolic syndrome and its components were analysed for relative daily energy expenditure groups and time spent watching television categories. RESULTS: After adjustment for gender, age and BMI, the OR of the metabolic syndrome in the most active subjects compared with the least active subjects was 0.27 [95% confidence interval (CI)=0.08-0.88; P=0.030]. There was inconclusive evidence of an association between watching television for more than 20h/week and presence of the metabolic syndrome (OR=2.99; 95% CI=0.83-10.84; P=0.095). CONCLUSIONS: Physical activity was a significant protective factor for presence of the metabolic syndrome and low levels of high-density-lipoprotein cholesterol. Watching television was positively associated with greater odds of high levels of triglycerides and fasting glucose. This study emphasized the importance of reducing the time spent watching television and increasing the level of physical activity for prevention of the metabolic syndrome.     

Metabolic syndrome and ischemic heart disease in elderly men and women

Associations between metabolic syndrome components and prevalent ischemic heart disease (IHD) were investigated in a cross-sectional, community-based study of elderly men (n = 1,015) and women (n = 1,259) in Rancho Bernardo, California, in 1984-1987. In both sexes, there were significant positive associations between IHD defined by resting electrocardiogram criteria and age, systolic blood pressure, fasting and postchallenge hyperglycemia, total cholesterol/high density lipoprotein cholesterol (HDL cholesterol) ratio, and triglycerides and an inverse significant association with HDL cholesterol. High collinearity and interactions between serum insulin and metabolic syndrome variables were accounted for by uncorrelated principal components identified by factor analysis. In both men and women, three uncorrelated principal components were identified, representing a central metabolic factor (body mass index, fasting and 2-hour serum insulin, high serum triglycerides, and low HDL cholesterol), a glucose factor, and a blood pressure factor. In a multivariate model with age and sex, all three factors were significantly associated with IHD by electrocardiogram criteria; central metabolic factor (odds ratio (OR) = 1.6, p = 0.001), glucose factor (OR = 1.4, p < 0.001), blood pressure factor (OR = 1.2, p = 0.005), age (10 years) (OR = 1.8, p < 0.001), and female sex (OR = 0.5, p < 0.02). Similar results were obtained in analyses using clinically manifest IHD as the outcome. These results support the thesis that the metabolic syndrome exerts effects through different risk factors by different mechanisms.     

南宁地区儿童青少年肥胖与代谢综合征相关性的流行病学研究

目的 分析儿童青少年肥胖与代谢综合征(MS)相关性及危险因素.方法 采用分层整群随机抽样方法从南宁市396所中小学抽取14所学校6～18岁中小学生7893人,进行体格检查及空腹血糖(FBG)、总胆固醇(TC)、甘油三酯(TG)、高密度脂蛋白胆固醇(HDL-C)、低密度脂蛋白胆固醇(LDL-C)、丙氨酸氨基转移酶(ALT)、天门冬氨酸氨基转移酶(AST)、空腹胰岛素(FINS)的血液生化检测,并计算胰岛素抵抗指数(HOMA-IR).结果 (1)MS患病率为正常组0.57％、超重组4.53％、肥胖组26.80％.(2)除HDL-C均值随肥胖增加而降低外,其余各指标均值、异常率比较均为肥胖组＞超重组＞正常组,3组间差异有统计学意义(P＜0.05).(3)对MS有影响的指标为腰围(OR=1.087,95％CI:1.033～1.143)、SBP(OR=1.073,95％CI:1.032 ～ 1.1 16)、FBG(OR=1.394,95％CI:1.568 ～3.423)、TG(OR=3.213,95％CI:1.410 ～ 7.319)、HDL-C(OR=0.001,95％ CI:0.000～0.012).结论 儿童青少年MS与肥胖密切相关,其患病率和危险因素随着肥胖程度的加重而增加.     

Risk of type 2 diabetes mellitus in young adults from a biracial community: the Bogalusa Heart Study

BACKGROUND: Since type 2 diabetes has a strong familial component, characteristics of young adult offspring of type 2 diabetics were examined in a community sample to determine early abnormalities in black and white persons at risk. METHODS: The sample consisted of 1,338 fasting young adults (72% white, 28% black) aged 19 to 37 years from a biracial community, including those with positive parental history of type 2 diabetes (one offspring per family, n = 230) or conditions of impaired fasting glucose and type 2 diabetes (n = 22). RESULTS: Positive family history of diabetes or impaired fasting glucose and type 2 diabetes in young adults of both races were significantly associated with adverse profiles of measures of obesity and abdominal fat (body mass index, triceps and subscapular skinfolds, waist circumference, and abdominal height), systolic and diastolic blood pressures, serum total cholesterol, triglycerides, VLDL cholesterol, and HDL cholesterol, and indicators of glucose homeostasis (plasma glucose and insulin and insulin resistance index). The magnitude of the differences in obesity and abdominal fat measures and plasma glucose between individuals with and without parental diabetes was greater among blacks versus whites (P = 0. 047-0.004). Further, black offspring of both diabetics and non-diabetics had unfavorable profiles of obesity and abdominal fat measures, blood pressure, insulin, and insulin resistance index (P = 0.0001). In a multivariate analysis, adiposity measured as body mass index (P = 0.03) and plasma glucose (P = 0.003) emerged as the two independent characteristics that distinguished those with parental diabetes from those without parental disease. Insulin (P = 0.0001) and the insulin resistance index (P = 0.0001) were independently associated with conditions of impaired fasting glucose or type 2 diabetes. CONCLUSIONS: The risk factors of young adults with parental type 2 diabetes or conditions of impaired fasting glucose and type 2 diabetes can be detected early. These observations have implications for early prevention and intervention, especially for blacks.     

Adolescent sex differences in adiponectin are conditional on pubertal development and adiposity

OBJECTIVE: Adiponectin is an adipose tissue protein with important insulin-sensitizing, anti-inflammatory, and cardioprotective properties but is paradoxically lower in obese individuals. Sex differences in adiponectin have been reported in adults and adolescents but not in prepubertal children. In this study, we hypothesized that sex differences in adiponectin would develop during puberty and would be influenced by level of adiposity. RESEARCH METHODS AND PROCEDURES: Adiponectin levels were measured in 1196 white and African-American adolescents. Insulin resistance was estimated using the homeostasis model (HOMA-IR). Demographic, developmental, and metabolic variables, including interactions with adiposity measurements, were evaluated for independent relationships with adiponectin levels. RESULTS: Overall, adiponectin levels varied significantly by sex, race, adiposity, and puberty stage. Significant sex differences in adiponectin developed after the onset of puberty, particularly in lean adolescents. Adolescent boys had lower adiponectin levels in post-puberty compared with pre-puberty (p = 0.01) and had lower levels than girls in both puberty and post-puberty (both p < 0.001), after adjusting for race, BMI z-score, and natural logarithm-(HOMA-IR). Sex differences were also conditional on adiposity level, with significant sex differences among lean (p < 0.001) but not among non-lean (p = 0.16) adolescents. Adiponectin levels in girls decreased more with increasing adiposity than in boys (p = 0.004), but only marginally so after standardizing for girls' higher mean adiponectin level (p = 0.11). DISCUSSION: Sex differences in adiponectin are dependent on both puberty stage and adiposity in adolescents, such that by post-puberty, non-lean boys exhibit the lowest levels of adiponectin.     

Relationship among fatness, blood lipids, and insulin resistance in Pakistani children

Observations on associations between fatness and metabolic risks among South-East Asian adults have resulted in devising lower thresholds of body mass index (BMI) for them. Metabolic abnormalities, including type 2 diabetes, are now also appearing in children and are associated with obesity. There has not been much work done to identify indicators of metabolic risks among South Asian children. This study was undertaken to observe the relationship among fatness, blood lipids, and insulin resistance in Pakistani children. Fatness, lipids, and insulin resistance were assessed in 92 middle-class Pakistani school children aged 8-10 years. Height, weight, waist, hips, mid-arm circumference, and triceps skin-fold, measured in school, were used for calculating various indicators of fatness, i.e. BMI, waist hip ratio (WHR), and arm-fat percentage. Fasting blood samples were analyzed for total lipids, triglycerides (TG), total cholesterol (TC), high density lipoprotein (HDL), low density lipoprotein (LDL), glucose and insulin levels. Homeostasis model assessment (HOMA) index was calculated to assess insulin resistance. Two separate multiple regression models of various risk indicators (family history, sex, BMI, WHR, arm-fat percentage) showed that only arm-fat percentage had a significant positive association both with insulin levels (b = 2.04, p = 0.044) and LDL (b = 2.11, p = 0.037). Only five children were overweight (BMI-for-age > 85th percentile according to National Center for Health Statistics 2000 reference). Neither overweight children nor those who were in the uppermost tercile of BMI-for-age differed significantly from other children in terms of presence of higher-than-desirable values of lipids or insulin. However, compared to those in the lowest tercile, children who were in the uppermost tercile of armfat percentage had a significantly higher frequency of high blood cholesterol (40% vs 67%, p = 0.027), high LDL (33.3% vs 61.3%, p = 0.026), and markedly higher proportion above average insulin levels (16.7% vs 35.5%, p = 0.083). Arm-fat percentage could be developed as a practical tool for determining the risk status of children. However, further cross-sectional assessments are needed to ascertain accurate relationships among arm-fat percentage, lipid profiles, and insulin resistance in larger and varied groups of children.     

Glucose and insulin components of the metabolic syndrome are associated with hyperandrogenism in postmenopausal women: the atherosclerosis risk in communities study

In 1990-1992, the authors investigated the association of total and free testosterone with the metabolic syndrome in postmenopausal US women not taking hormone replacement therapy (n=362) in a prevalent case-control study of carotid atherosclerosis. Free testosterone was estimated by using the free androgen index (FAI) (total testosterone/sex hormone-binding globulin ratio). The metabolic syndrome was defined as the presence of three or more of the following criteria: waist circumference > or =35 inches (88.9 cm), triglycerides > or =150 mg/dl, high density lipoprotein cholesterol <40 mg/dl, blood pressure >130/80 mmHg, fasting insulin > or =100 pmol/liter, or impaired glucose homeostasis (fasting glucose > or =110 mg/dl or diagnosed diabetes mellitus). FAI, but not total testosterone, was strongly associated with the metabolic syndrome. Compared with women in the lowest FAI quartile, those in the highest quartile had a fivefold greater odds of having the metabolic syndrome (odds ratio=5.38, 95% confidence interval: 2.70, 10.7) after adjustment for age, race, and carotid atherosclerosis status. In multivariate analyses, the three-component metabolic syndrome combinations that contained both hyperinsulinemia and hyperglycemia were most strongly associated with increased FAI (absolute increase=0.41-0.54 compared with that for women who did not have these combinations; all p's < 0.001). Higher FAI was associated with the hyperinsulinemia and hyperglycemia components of the metabolic syndrome. The role of androgens in glucose homeostasis in postmenopausal women requires further study.     

Percentage body fat ranges associated with metabolic syndrome risk: results based on the third National Health and Nutrition Examination Survey (1988-1994)

BACKGROUND: Increasing attention has focused on the association between body fatness and related metabolic risk factors. The quantitative link between percentage body fat (%BF) and the risk of metabolic syndrome is unknown. OBJECTIVES: The objectives were to determine the risk [odds ratios (ORs)] of metabolic syndrome based on %BF in black and white men and women in the United States and to provide corresponding ranges of %BF associated with a risk equivalent to body mass index (BMI; in kg/m(2)). DESIGN: The subjects were participants in the third National Health and Nutrition Examination Survey and were divided into those with and without the metabolic syndrome. OR equations were derived from logistic regression models for %BF and BMI, with the 25th percentile in the study population as the reference. Ranges were developed by associating %BF with the equivalent risk of metabolic syndrome based on established BMI cutoffs. RESULTS: Four sets (men, women, black, and white) of OR curves were generated for %BF and for BMI by using data from 8259 adults. The ORs for metabolic syndrome were lower in blacks than in whites at any given %BF or BMI. The developed cutoffs for %BF differed between men and women but showed only small race and age effects. A simplified set of sex-specific %BF ranges for the risk of metabolic syndrome were developed. CONCLUSIONS: The risk of metabolic syndrome can be established from measured %BF by using either the developed OR curves or %BF thresholds at traditional BMI cutoffs. This information should prove useful in both clinical and research settings.     

Prevalence of non-traditional cardiovascular disease risk factors among persons with impaired fasting glucose, impaired glucose tolerance, diabetes, and the metabolic syndrome: analysis of the Third National Health and Nutrition Examination Survey (NHANES III)

PURPOSE: To calculate the prevalence of non-traditional cardiovascular disease (CVD) risk factors across diabetes status and for persons with and without the metabolic syndrome. METHODS: Data were analyzed from the Third National Health and Nutrition Examination Survey for normal plasma glucose [<100 mg/dl, n=4589]; impaired fasting glucose [IFG, 100-125 mg/dl, n=2008], diabetes [fasting glucose #10878; 126 mg/dl or diabetes medication, n=750]; and participants with and without the metabolic syndrome, n=1938 and n=5409, respectively. RESULTS: After adjustment for age, race, sex, body mass index, physical inactivity, cigarette smoking and alcohol consumption, a higher odds (p-trend < 0.01) of the metabolic syndrome, an elevated HOMA-insulin resistance index, chronic kidney disease, elevated C-reactive protein, high fibrinogen, and high white blood cell count was observed across diabetes status. After similar adjustment, the metabolic syndrome was associated with (odds ratio; 95% confidence interval) low apolipoprotein A1 (2.27: 1.30,3.96), high apolipoprotein-B (2.97: 2.03,4.34), a higher HOMA insulin resistance index (5.25: 4.16, 6.63), chronic kidney disease (2.27: 1.42, 3.63), and elevated markers of inflammation [high white blood cell count (1.55: 1.14, 2.10), and elevated C-reactive protein (1.46: 1.06, 2.00)]. Among participants with IFG, the presence of impaired glucose tolerance (IGT) was associated with a higher prevalence of the HOMA insulin reistance index, 32.3%, high fibrinogen, 18.5%, and elevated C-reactive protein, 13.2%, compared to persons with IFG alone, 19.7%, 13.3% and 5.7%, respectively (each p <== 0.05). CONCLUSIONS: In this representative of the US population, an increased prevalence of non-traditional CVD risk factors was present among persons with diabetes, IGT and IFG compared to IFG alone, and the metabolic syndrome.     

Cardiovascular risk factors clustering features of insulin resistance syndrome (Syndrome X) in a biracial (Black-White) population of children, adolescents, and young adults: the Bogalusa Heart Study.

Recently, independent factors representing different features of insulin resistance syndrome (Syndrome X) have been identified by factor analysis in middle-aged and elderly adult populations. In this study, factor analysis was applied to the clustering characteristics of Syndrome X in a biracial (Black-White) community-based population of 4,522 children (ages 5-11 years), adolescents (ages 12-17 years), and young adults (ages 18-38 years) from the Bogalusa Heart Study who were screened during 1988-1996. Ponderal index (weight (kg)/height (m)3), levels of insulin, glucose, triglycerides, and high density lipoprotein cholesterol, and systolic and diastolic blood pressure were used as measures of components of Syndrome X. No evidence was found to support a one-factor hypothesis for this syndrome, but factor analysis yielded two uncorrelated factors (factor 1: insulin/lipids/glucose/ponderal index; factor 2: insulin/blood pressure). These two factors explained 54.6% of the total variance in the entire sample. The factor loading patterns were very similar in all race and age groups, based on high values of coefficients of congruence (0.89-1.0). These results suggest that Syndrome X is characterized by the linking of a metabolic entity (hyperinsulinemia/insulin resistance, dyslipidemia, and obesity) to a hemodynamic factor (hypertension) through shared correlation with hyperinsulinemia/insulin resistance, and that the clustering features are independent of sex and age in both Black and White populations.     

Race and gender differences in serum lipoproteins of children, adolescents, and young adults--emergence of an adverse lipoprotein pattern in white males: the Bogalusa Heart Study.

METHODS. Serum lipoprotein profiles in 4,231 individuals, ages 5-26 years, were studied cross-sectionally in a biracial community to describe the race- and gender-specific changes from adolescence into young adulthood. RESULTS. White children and adolescents of both genders showed significantly higher covariates--adjusted triglycerides (9-11 mg/dl) and very-low-density lipoprotein cholesterol (1-2 mg/dl)--and lower total cholesterol (3-14 mg/dl) and high-density lipoprotein cholesterol (6-10 mg/dl) levels than their black counterparts. These black-white differences persisted among young adults of both genders with the exception of total cholesterol levels (higher triglycerides: 23-32 mg/dl; higher very-low-density lipoprotein cholesterol: 5-7 mg/dl; lower high-density lipoprotein cholesterol: 9-11 mg/dl); in addition, white young adult males began to show higher levels of low-density lipoprotein cholesterol (14 mg/dl) than black young adult males. A consistent gender-related pattern emerged only among white young adults with males showing higher triglyceride levels (22 mg/dl), very-low-density lipoprotein cholesterol (5 mg/dl), and low-density lipoprotein cholesterol (10 mg/dl) and lower high-density lipoprotein cholesterol (10 mg/dl) than females. Lipoprotein changes from adolescence into young adulthood were more pronounced among white males than other race-gender groups, resulting in higher triglyceride, very-low-density lipoprotein cholesterol, and low-density lipoprotein cholesterol, a higher total cholesterol/high-density lipoprotein cholesterol ratio, and a lower high-density lipoprotein cholesterol in their young adulthood. According to the National Cholesterol Education Program criteria, a relatively higher proportion of young adult white males was classified as borderline-high (22.6%) or high (9.1%) for low-density lipoprotein cholesterol. Adiposity was the major contributor to the adverse lipoprotein pattern, especially among white males. Sexual maturation and age influenced the lipoprotein levels to a greater extent among white males. Cigarette smoking, alcohol intake, and oral contraceptive use began to emerge as minor but significant factors contributing to the lipoprotein levels in adolescents and young adults. CONCLUSION. These results underscore the desirability of early targeting for primary prevention.     

Association of total and central adiposity measures with fasting insulin in a biracial population of young adults with normal glucose tolerance: the CARDIA study.

OBJECTIVE: To determine the association of computed tomography (CT)-measured visceral adipose tissue (AT) and other measures of adiposity with fasting insulin in a biracial (African American and Caucasian) study population of young adults. RESEARCH METHODS AND PROCEDURES: The study population consisted of 251 young adults with normal glucose tolerance (NGT), ages 28-40 years, who were volunteers from the Birmingham, Alabama, and Oakland, California centers of the Coronary Artery Risk Development in Young Adults (CARDIA) study. RESULTS: In regression models with total adiposity measures (body mass index or dual-energy X-ray absorptiometry-measured percent fat), visceral AT (measured as a cross-sectional area in cm2) was generally a stronger predictor of insulin than overall adiposity in all race/gender groups (partial correlation coefficients ranging from 0.31 to 0.47) except for black men, in whom the associations were nonsignificant. Partial correlation coefficients between waist circumference and insulin, controlling for percent fat, were nearly identical to those between visceral AT and insulin in women and in white men. Analyses performed on 2060 NGT CARDIA subjects who were not in this study of visceral AT showed significant correlations of waist circumference with insulin in all race/gender groups, including black men, and that black men in the visceral AT study group were significantly leaner than other black male CARDIA subjects. DISCUSSION: We conclude that visceral AT was associated with fasting insulin in NGT participants in three of the four race/gender groups (black men excepted) and that waist circumference was a good surrogate for visceral AT in examining associations of central adiposity with fasting insulin.     

Pathophysiologic mechanisms of obesity and related metabolic disorders: an epidemiologic study using questionnaire and serologic biomarkers

BACKGROUND: It is still unclear whether individuals with the same degree of obesity but different weight histories since young adulthood have different insulin concentration, prevalence of metabolic syndrome components and their clustering. METHODS: A cross-sectional study was conducted on 3,399 (for weight difference analysis) and 1,879 (for weight fluctuation analysis) Japanese men aged 40-59 years. Weight difference was calculated by subtracting the recalled weight at about 25 years old from the current weight. The root mean square error around the slope of weight on age (weight-RMSE) was calculated by a simple linear regression model, in which the subject's actual weights at ages 20, 25, 30, 40 years and 5 years prior to the study, as well as current weight, were dependent variables against the subject's age as the independent variable. Each metabolic syndrome component was defined as follows: serum triglycerides > or =150 mg/dL; HDL-cholesterol <40 mg/dL; fasting glucose > or =110 mg/dL; and blood pressure > or =140/90 mm Hg. RESULTS: Those who gained <10%, <20%, or 20% or more in weight had a significantly higher than unity odds ratio of having two or more metabolic syndrome components in relation to those whose weight remained stable: 1.28 (95% confidence interval: 0.95-1.73), 2.49 (1.91-3.24), and 5.30 (3.97-7.07), respectively. Weight-RMSE was significantly and positively associated with fasting insulin concentration independent of current weight, weight-slope or other lifestyle-related factors. CONCLUSIONS: Metabolic syndrome components would likely tend to cluster more in individuals with large weight gain on a physiologic basis characterized by high fasting insulin concentration. Furthermore, weight fluctuation was suggested to increase the risk of fasting hyperinsulinemia.     

青少年肥胖与代谢综合征关系的研究

目的分析不同营养状况青少年的脂代谢、糖代谢和血压状况,研究青少年肥胖与代谢综合征（MS）的关系。方法选择北京市东城区初中生966名,进行身体测量和血压、血脂、空腹血糖和胰岛素测定。结果不同营养状况青少年血压（SBP和DBP）、血脂（TC,TG,LDL-C）和空腹胰岛素（FINS）水平差异均有统计学意义（P值均〈0.05）,均随体重指数（BMI）增加而上升;空腹血糖（FPG）差异无统计学意义（P〉0.05）;除FPG,HDL-C外,其余MS指标异常检出率均为肥胖组〉超重组〉体重正常组（P值均〈0.05）。结论青少年肥胖与MS发生密切相关。肥胖青少年已经出现代谢紊乱,应重视并积极防治。