Lack of independent relationship between plasma adiponectin, leptin levels and bone density in nondiabetic female adolescents

OBJECTIVES: Adiponectin has been implicated in the pathophysiology of metabolic syndrome and coronary artery disease in humans. Whether adiponectin is related to bone mineralization remains unclear in adults as well as in adolescents. In this study, we aimed to determine the relationship between plasma adiponectin, leptin concentrations and bone density, including total-body bone mineral density (BMD) and bone mineral content (BMC) in adolescence. PATIENTS AND MEASUREMENTS: We studied 105 nondiabetic female adolescents [mean age 15.4 +/- 1.9 years, and mean body mass index (BMI), 23.1 +/- 4.0 kg/m(2)]. A venous blood sample was taken after 12 h of fasting to measure fasting plasma adiponectin and leptin levels. BMD and BMC of the whole body were measured by dual-energy X-ray absorptiometry. RESULTS: In simple correlation analysis, plasma adiponectin and leptin levels correlated significantly with total-body BMD (r =-0.523 and r = 0.443, P < 0.001, respectively) and BMC (r =-0.471 and r = 0.396, P < 0.001, respectively). However, plasma adiponectin and leptin were related to both BMD and BMC in opposite directions. In multivariate linear regression analyses, only BMI or fat mass (FM) and Tanner stage, but not plasma adiponectin and leptin, were significantly related to BMD and BMC following adjustment for other variables. CONCLUSIONS: The results suggest that plasma adiponectin and leptin concentrations are not related to the total-body BMD and BMC independent of the chronological age, BMI or FM, and Tanner stage in nondiabetic female adolescents, although they were highly correlated in simple correlation analyses. The biologic roles of adiponectin in bone still need further clarification.     

Plasma plasminogen activator inhibitor-I is associated with plasma leptin irrespective of body mass index, body fat mass, and plasma insulin and metabolic parameters in premenopausal women.

Leptin, the satiety hormone expressed almost exclusively in adipose tissue, is a marker of body fat accumulation in humans. Recent studies have shown that plasminogen activator inhibitor-1 (PAI-1), a prothrombotic factor associated with atherosclerosis complications, is also produced in adipose tissue. The objective of the present study was to determine whether PAI-1 antigen plasma concentrations are associated with leptin plasma levels or the body fat mass (FM) independently of the variables known to influence PAI-1 production. Sixty-one nondiabetic women aged 18 to 45 years with a wide range of values for the body mass index ([BMI] 18.1 to 37.7 kg/m2) were evaluated for (1) body FM and fasting plasma levels of (2) PAI-1 antigen, (3) PAI-1 activity, (4) leptin, (5) insulin, (6) blood glucose, and (7) lipids (cholesterol, high-density lipoprotein [HDL]-cholesterol, and triglycerides [TG]). Body FM and fat-free mass (FFM) were estimated during fasting conditions by the bioimpedance analysis (BIA) method using a tetrapolar device. Body fat distribution was evaluated by the waist circumference and the waist to hip ratio (WHR). FM was directly associated with both PAI-1 antigen (r = .585, P < .001) and PAI-1 activity (r = .339, P < .001). Seemingly, leptin was positively related to both PAI-1 antigen (r = .630, P < .001) and PAI-1 activity (r = .497, P < .001). Moreover, both PAI-I antigen and PAI-1 activity were directly correlated with FFM (r = .285, P < .05, and r = .336, P < .01, respectively), BMI (r = .594, P < .001, and r = .458, P < .001, respectively), and WHR (r = .510, P < .001, and r = .391, P < .005, respectively). Insulin was directly related to PAI-1 antigen (r = .540, P < .001), PAI-1 activity (r = .259, P < .05), leptin (r = .447, P < .001), and FM (r = .435, P < .001). The association between PAI-1 antigen (dependent variable) and leptin or FM was tested by a stepwise regression model simultaneously including leptin, FM, BMI, WHR, age, FFM, and fasting insulin, blood glucose, TG, cholesterol, and HDL-cholesterol as independent variables. PAI-1 antigen maintained a significant positive independent relationship only with leptin (t = 2.923, P < .01), insulin (t = 3.489, P < .001), and fasting blood glucose (t = 2.092, P < .05), and a negative independent relationship with HDL-cholesterol (t = -2.634, P < .05). In conclusion, the strong relationship between PAI-1 antigen and leptin irrespective of other variables known to influence these factors seems to indicate that leptin per se may potentially increase PAI-1 plasma concentrations in obese subjects.     

Excess accumulation of body fat is related to dyslipidemia in normal-weight subjects

OBJECTIVE: To assess the relationship of fat mass (FM) and its distribution to hypertension and dyslipidemia in normal-weight Japanese individuals. DESIGN: Cross-sectional study. SUBJECTS: Apparently healthy Japanese subjects with a body mass index (BMI) between 20 and 23.5 kg/m(2) (265 males and 741 females, age 21-69 y). MEASUREMENTS: BMI, waist circumference (WC), waist-hip ratio (WHR), systolic and diastolic blood pressure, serum levels of total cholesterol (TC), high-density lipoprotein-cholesterol (HDL-C) and triglyceride (TG) were measured. Low-density lipoprotein-cholesterol (LDL-C) was calculated by the Friedewald formula. Percentage fat mass (%FM) and trunk fat mass-leg fat mass ratio (FM(trunk)/FM(legs)) were obtained by dual-energy X-ray absorptiometry. RESULTS: WC, WHR, %FM and FM(trunk)/FM(legs) were significantly correlated with TC, LDL-C, HDL-C and TG with the tendency of FM(trunk)/FM(legs) to show the strongest correlations. For %FM and FM(trunk)/FM(legs) in both sexes, odds ratios (ORs) of the third tertiles with respect to the first tertiles increased for LDL-C elevation, TG elevation and dyslipidemia. In males, ORs of the third tertiles of WC were significantly high for LDL-C elevation and dyslipidemia whereas those of WHR were high for TG elevation and dyslipidemia. ORs of the third tertiles of WC and WHR were significantly high for TG elevation in females. BMI was not associated with the risk of abnormal lipid levels. ORs for hypertension showed significant increases in none of the variables of obesity. CONCLUSIONS: Excess accumulation of FM, especially to the upper body, was related to dyslipidemia in normal-weight subjects. Simple anthropometric variables, WC and WHR, may be useful for screening and management of dyslipidemia in these subjects.     

Relationship between plasminogen activator inhibitor-1 antigen, leptin, and fat mass in obese children and adolescents

Hyperleptinemia may be associated with cardiovascular risk and is linked with parameters of fibrinolytic processes in adults. We studied whether body fatness, leptin, and insulin interact with plasminogen activator inhibitor-1 antigen (PAI-1-Ag) and tissue-type plasminogen activator antigen (tPA-Ag) in obese children and adolescents. Twenty-three boys (mean +/- SD: age, 10.7 +/- 3.3 years; body mass index [BMI], 28.7 +/- 5.4 Kg/m2) and 19 girls (age, 11.9 +/- 2.7 years; BMI, 29.4 +/- 4.8 Kg/m2) were investigated. Body fat mass (FM) in the children was calculated by bioelectrical impedance analysis, and blood samples were obtained for leptin, insulin, C-peptide, PAI-1-Ag, and tPA-Ag. The children were divided into 3 subgroups according to maturation. Maturity was associated with greater adiposity and higher levels of leptin and C-peptide, but insulin and PAI-1-Ag were not different between prepubertal, pubertal, and late/postpubertal children. PAI-1-Ag was associated with leptin and insulin, but not after adjustment for fatness. PAI-1-Ag was independently associated with tPA-Ag (r = .36, P < .02). Multiple regression analysis showed that tPA-Ag failed to reach the level of significance (P = .07), but FM contributed to the variation in PAI-1-Ag (adjusted R2 = .29). The BMI was the main determinant for the variation in leptin (adjusted R2 = .386) and in insulin (adjusted R2 = .60, all P < .001). Neither gender, maturation, chronological age, or leptin contributed significantly to the variation in either PAI-1-Ag or tPA-Ag. Our data suggest that adiposity and other variables contribute to higher levels of PAI-1-Ag. Leptin seems not to be independently linked with fibrinolytic parameters, but an unfavorable metabolic and fibrinolytic risk profile might emanate from the obese pubertal stage.     

Adipocytokines, fat distribution, and insulin resistance in elderly men and women

BACKGROUND: The aim of this study was to evaluate the relation between adiponectin and leptin, fat distribution, and insulin resistance in elderly men and women. METHODS: 68 elderly participants (28 men and 40 women) aged 66-77 years, with body mass index (BMI) ranging from 19.83 to 37.18 kg/m2, participated in the study. In all participants, we evaluated BMI, waist and hip circumferences, sagittal abdominal diameter (SAD), fat mass (FM) by dual energy X-ray absorptiometry, fasting and 2-hour glucose, insulin, homeostasis model assessment of insulin resistance (HOMA), leptin, and adiponectin. RESULTS: Elderly women had significantly higher circulating levels of adiponectin and leptin compared to men even after adjusting for age, FM, or waist circumference. In men and women, leptin was positively associated, whereas adiponectin was negatively associated, with BMI, indices of body fat distribution, as well as FM and FM%. Both fasting insulin and HOMA showed significant positive correlation with leptin and negative correlation with adiponectin in both sexes. In a step-wise multiple regression model with HOMA as the dependent variable and age, gender, waist circumference, FM, leptin, and adiponectin as independent variables, waist entered the regression first, explaining 19.7% of HOMA variance, leptin was second, and adiponectin was third, explaining each one an additional 10% of variance. In a multiple linear regression analysis, leptin and adiponectin alone explained up to 38% of HOMA variance. CONCLUSION: Leptin and adiponectin together seem to be strictly related to insulin resistance in elderly people, independently of body fat and body fat distribution.     

Plasma leptin concentrations and obesity in relation to insulin resistance syndrome components among school children in Taiwan--The Taipei Children Heart Study

OBJECTIVE: Leptin, an adipose tissue-derived product of the obesity (OB) gene, is an important regulator of energy metabolism and may be associated with the occurrence of insulin resistance and diabetes in humans. The purpose of this study was to evaluate the association of plasma leptin concentration with obesity and the components of insulin resistance syndrome (IRS) among school children in Taiwan. METHODS: After multistage sampling of 85 junior high schools in Taipei, we randomly selected 1,264 children (617 boys and 647 girls) aged 12-16y. Obesity measurements included body mass index (BMI) and waist-to-hip circumference ratio (WHR). We calculated an IRS summary score for each individual by adding the quartile ranks from the distribution of systolic blood pressure (BP), serum triglyceride (TG), HDL-cholesterol (inverse), and insulin levels. RESULTS: Boys had a higher BMI and WHR, BP and IRS score and lower leptin, insulin, TG and HDL-C levels than girls. BMI, WHR and plasma leptin levels were significantly associated with the IRS summary score and each of its components in both genders. Children with higher plasma leptin levels (> 75th percentiles) have significantly higher BP, TG, insulin levels and IRS score than children with low leptin levels. The associations between plasma leptin level and the IRS components and score were still significant after adjusting for BMI in boys, but less so in girls. In both genders, after adjusting for WHR, plasma leptin levels were still significantly associated with the IRS components and summary score (P< 0.001). The final model that included the standard covariates, BMI and leptin, but not WHR, was the most predictive of the IRS summary score among school children. CONCLUSIONS: Insulin resistance syndrome in childhood, characterized by high blood pressure, dyslipidemia, and hyperinsulinemia, may be an early marker of cardiovascular risk. From the present BMI and leptin in combination are the most predictive markers of insulin resistance syndrome among school children in Taiwan.     

Distribution and determinants of adiponectin, resistin and ghrelin in a randomly selected healthy population

OBJECTIVE: Adiponectin, resistin, ghrelin and the IGF-I system seem to play an important role in the regulation of body composition throughout life, but the mechanisms are not well understood. The aim of our study was to analyse the distribution among sexes and all decades of the adult life of adiponectin, resistin and ghrelin and their relationship with anthropometric, body composition parameters and the IGF-I system. SUBJECTS: One hundred and thirty-four men and 127 healthy women were included in the study. MEASUREMENTS: Plasma concentration of adiponectin, resistin, ghrelin, total IGF-I, free IGF-I and IGFBP-3 were determined in all subjects. Body composition was evaluated by bioelectrical impedance. RESULTS: Resistin and ghrelin were not affected by age. Plasma adiponectin correlated negatively with age, body mass index (BMI), waist-to-hip ratio (WHR), waist circumference (WC), fat mass (FM) and body fat (BF) in men. Adiponectin correlated negatively with WHR and positively with free IGF-I in women. Resistin correlated positively with BMI and WC only in men, and ghrelin correlated positively with WC, BMI and FM and negatively with free IGF-I in men. In multiple regression analysis adiponectin remained associated with WHR (beta=-0.19, P=0.01) in women. Resistin was positively associated with BMI (beta=0.30, P=0.003) in women and ghrelin was negatively related to free IGF-I (beta=-0.158, P=0.019) in men. CONCLUSIONS: Plasma adiponectin declines with age and is negatively associated with FM in men. Our data suggest the existence of a positive correlation of adiponectin and the IGF-I axis in women and of an inverse relationship between ghrelin and the IGF-I system in men.     

Lean, nondiabetic Asian Indians have decreased insulin sensitivity and insulin clearance, and raised leptin compared to Caucasians and Chinese subjects

OBJECTIVE: To study and compare the insulin sensitivity of healthy, nondiabetic Asian Indians with that of two other ethnic groups (Caucasian and Chinese) living in Singapore. DESIGN: Study of insulin sensitivity using euglycaemic hyperinsulinaemic glucose clamp. SUBJECTS: A total of 10 healthy, lean, young male subjects of each ethnic group, matched for age, body mass index (BMI) and physical activity. They all had normal glucose tolerance and had no family history of diabetes. MEASUREMENTS: Anthropometric parameters (BMI, waist-hip ratio (WHR) and percentage body fat (PBF)), fasting lipid profile and leptin concentration, insulin sensitivity index, and insulin clearance. RESULTS: Healthy lean (BMI 22.1+/-1.5 kg/m(2) (mean+/-s.d.)) Indians had significantly higher fasting serum leptin (5.1+/-2.5 vs Chinese 1.0+/-0.9 vs Caucasian 2.3+/-1.2 ng/ml; P<0.001), lower insulin sensitivity index (9.9+/-3.3 vs Chinese 14.1+/-3.5 vs Caucasian 18.8+/-9.2 mg/min kg fat-free mass/microU/ml; P<0.002), and lower insulin clearance (461.4+/-54.8 vs Chinese 621.0+/-99.3 vs Caucasian 646.9+/-49.2 ml/min m(2); P<0.001). Indians also had a higher PBF (26.5+/-5.2 vs Chinese 19.5+/-2.2 vs Caucasians 22.9+/-1.4%; P<0.001), diastolic blood pressure (P=0.036), fasting insulin (P<0.006) and fasting triglyceride (P=0.022). Stepwise regression analysis showed that ethnicity was the only significant independent determinant variable for the differences in insulin sensitivity index (P=0.008). CONCLUSION: Healthy lean nondiabetic Indians were more insulin resistant compared to other ethnic groups despite the similarity in living environment. These findings may warrant preventive health-care strategies for type II diabetes and coronary artery disease to target Indians at an earlier stage compared to other ethnic groups.     

Comparison of fasting plasma leptin concentrations in healthy subjects with high and low plasma insulin

This study was initiated to evaluate the role of hyperinsulinemia in the regulation of fasting plasma leptin. We measured plasma leptin and insulin concentrations in 404 healthy nondiabetic subjects. For analytical purposes, the population was divided into quartiles on the basis of the lowest (quartile 1) and highest (quartile 4) plasma insulin response to oral glucose, and fasting plasma leptin values in these 2 dichotomous groups were compared. The total plasma integrated insulin response was 4-fold greater in quartile 4, associated with significantly higher (P < .001) fasting plasma leptin (12.60+/-0.85 v8.53+/-0.56 ng/mL). Fasting plasma leptin concentrations remained significantly higher in the hyperinsulinemic quartile when comparisons were made after subdividing the population on the basis of gender, body mass index (BMI), or waist to hip ratio (WHR). These results demonstrate that fasting plasma leptin concentrations are significantly higher in hyperinsulinemic individuals, and this difference is independent of either overall or central obesity.     

阻塞性睡眠呼吸暂停低通气综合征与胰岛素抵抗的关系

目的探讨阻塞性睡眠呼吸暂停低通气综合征（OSAHS）与胰岛素抵抗（IR）的关系。方法选男性肥胖OSAHS患者60例（肥胖OSAHS组）、非OSAHS肥胖男性60例（肥胖非OSAHS组）、体重正常非OSAHS男性60例（正常体重非OSAHS组）,计算3组受试者的腰臀比和体重指数（BMI）;观察脉搏血氧饱和度（SpO2）;测空腹血糖,用高度特异的单克隆抗体夹心放大酶联免疫分析法测真胰岛素（TI）,IR的体内稳定状态模式评估方法（HOMA-IR）评估IR;行多导睡眠图（PSG）监测,计算呼吸暂停低通气指数（AHI）。结果同样是肥胖者,肥胖OSAHS组TI、HOMA—IR高于肥胖非OSAHS组,而最低SpO2低于肥胖非OSAHS组;在非OSAHS者中,肥胖非OSAHS组TI、HOMA-IR高于正常体重非OSAHS组,而最低SpO2低于正常体重非OSAHS组。协方差分析校正年龄、BMI、腰臀比的影响后,肥胖OSAHS组的TI、HOMA-IR仍明显高于肥胖非OSAHS组和正常体重非OSAHS组,肥胖非OSAHS组的TI、HOMA—IR明显高于正常体重非OSAHS组。多元线性回归分析显示MTU、HOMA—IR均与年龄和最低SpO2呈负相关,与BMI、腰臀比、AHI呈正相关;当以TU作因变量时,腰臀比是影响肥胖OSAHS组IR的主要因素,AHI与最低SpO2是TI的独立影响因素;当以HOMA—IR作因变量时,腰臀比是其主要影响因素,AHI与最低SpO2是其独立影响因素。结论OSAHS与IR独立相关,OSAHS可能经IR这一中间途径导致心血管疾病。     

Body mass, plasma leptin, glucose, insulin and C-peptide in offspring of diabetic and non-diabetic mothers.

OBJECTIVE: The aim was to investigate the relationship between body mass index (BMI), plasma leptin, glucose, insulin and C-peptide levels in the offspring of diabetic mothers (DM) and non-diabetic healthy mothers (HM). DESIGN: Seventy-two offspring (37 girls and 35 boys, age 4-20 years) of DM were investigated in a prospective study. Those 14-16 years old (Tanner stage II-IV) were compared with age-matched offspring of HM (33 girls and 33 boys). RESULTS: BMI strongly correlated with plasma leptin concentration in the offspring of both DM and HM children. There were higher BMI and plasma leptin and glucose levels in DM than in HM children. There was no difference in plasma insulin or C-peptide levels between HM and age-matched DM children. There was a highly significant positive correlation between plasma leptin and C-peptide in boys of DM. CONCLUSIONS: The higher plasma leptin found in the offspring of DM reflects their higher BMI. A moderately high but still normal glycemia might be a preclinical sign of insulin resistance or other disturbance of glucoregulation.     

Serum leptin concentration in moderate and severe obesity: relationship with clinical, anthropometric and metabolic factors

OBJECTIVE: To study clinical, anthropometric and metabolic determinants of serum leptin concentrations in a series of patients with a wide range of obesity. SUBJECTS: 400 patients, 116 males and 284 females, aged 44+/-12.3 years with body mass index (BMI) ranging from 31 to 82 kg/m2 (mean 41.4+/-7.1). MEASUREMENTS: Energy intake by 7-day recall, resting energy expenditure (REE) by indirect calorimetry, body composition determined by bioelectrical impedance; C index, an anthropometric index of abdominal fat distribution, and waist-hip ratio (WHR), blood glucose serum leptin concentrations, total cholesterol, high-density lipoprotein (HDL) cholesterol, triglycerides, uric acid, and insulin concentrations HOMA IRI (homeostastis model assessment of insulin resistance index). RESULTS: Leptin concentrations were higher in obese than in normal subjects and in females than in males without differences between diabetic and non-diabetic patients; leptin concentrations were not related to age and showed a strong negative association with energy intake only in the group of women with BMI less than 40. Leptin concentrations showed a direct correlation with BMI and body fat values (expressed either as percentage of total body mass or absolute fat mass) independent of age and sex. After adjustment for fat mass, leptin values higher than predicted were found in women whereas concentrations lower than predicted were found predominantly in men. Leptin showed an inverse correlation with WHR and C-index, the latter persisting also after correction for gender and fat mass. REE, but not REE/kg fat-free mass (FFM) was inversely related to leptin also after correction for sex and absolute fat mass. Leptin concentrations were directly associated with HOMA IRI, insulin and HDL cholesterol and inversely associated with triglycerides and uric acid. The relationship of leptin with HOMA IRI was still evident after adjusting for sex but was lost when absolute fat mass was added to the model; HDL cholesterol and triglycerides appeared to be variables independent of leptin concentrations even when both sex and fat mass were added to the model. CONCLUSIONS: In a large group of obese patients (half of whom had severe obesity, gender, BMI and fat mass accounted for the largest proportion of serum leptin concentrations variability. We found that in obese subjects there is an effect of fat distribution on leptin concentrations and that, after excluding variability due to absolute fat mass, patients with a greater amount of abdominal fat have relatively low leptin concentrations which in turn relates to a metabolic profile compatible with an increased cardiovascular risk. Women with milder obesity may retain some degree of control of food intake by leptin.     

Importance of plasma leptin in predicting future weight gain in obese children: a two-and-a-half-year longitudinal study

OBJECTIVE: To determine whether relatively low leptin levels predict changes in adiposity in prepubertal and pubertal obese children. RESEARCH METHODS AND PROCEDURES: In a biracial cohort of 68 obese children (33 male and 35 female; 46 Caucasians and 22 African-Americans, age range 7-18 y), we measured at baseline fasting insulin and leptin levels, height and weight and calculated body mass index (kg/m(2)) and expressed body mass index as (BMI) Z-score. After a 2.5-y follow-up, anthropometric measurements were repeated and changes in weight gain were calculated as changes in BMI Z-score. RESULTS: At baseline obese preadolescent boys and girls had similar age and BMI Z-score, fasting insulin and leptin levels. After an average follow-up of 2.5 y, mean weight change calculated by changes in BMI Z-score from baseline was similar in both groups. In obese adolescent boys and girls at baseline, no significant gender differences were observed for BMI Z-score and insulin levels. In contrast, plasma leptin levels were significantly higher in obese girls compared with obese adolescent boys. At follow-up, there was no significant difference in change in BMI Z-score between obese boys and girls. Multiple linear regression analysis revealed that high basal leptin levels were positively associated with greater changes in BMI Z-score only in girls (r(2)=0.18, P<0.02), after adjusting for basal BMI Z-score, Tanner stage, years of follow-up and basal insulin. High basal leptin levels in girls explained 18% of the weight gain. CONCLUSION: High leptin levels are associated with excessive future weight gain only in girls.     

Association between insulin resistance and metabolic syndrome risk factors in Japanese

Aims/Introduction: It is important to identify individuals at risk of metabolic syndrome (MetS), namely those with insulin resistance. Therefore, the aim of the present study was to find anthropometric and metabolic parameters that can better predict insulin resistance. Subjects and Methods: We selected 3899 individuals (2058 men and 1841 women), excluding those with fasting plasma glucose (FPG) ≥126 mg/dL, on medication for hypertension, dyslipidemia or diabetes, and those with a history of advanced macrovascular disease. Using multivariate analyses, we selected components for obesity, lipids, and blood pressure based on the strength of their association with the homeostasis model assessment of insulin resistance (HOMA‐IR). Results: In multiple linear regression analysis, body mass index (BMI), waist circumference (WC), triglycerides (TG), high‐density lipoprotein–cholesterol (HDL‐C), and systolic blood pressure (SBP) were selected in men and women, and the effect of BMI on HOMA‐IR outweighed that of WC. In multiple logistic regression analysis, BMI, TG, and SBP were significantly associated with HOMA‐IR ≥2.5 in both genders, but WC and HDL‐C were only selected in men. Combinations of BMI, TG, SBP, and FPG showed higher HOMA‐IR values than those of the existing MetS components, considered useful for the identification of individual with higher insulin resistance. Conclusions: Body mass index, TG and SBP were selected as components significantly related to insulin resistance. The selected components were fundamentally adherent to the existing MetS criteria, the only difference being the measure of obesity, in which a stronger association with insulin resistance was observed for BMI than WC. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2011.00162.x, 2011)     

Decreased plasma adiponectin concentrations in nondiabetic women with elevated homeostasis model assessment ratios

OBJECTIVE: Whether the adipocyte-derived protein adiponectin is associated with insulin resistance independently of the effects of adiposity and the diabetic state is an important question. We explored, in a cross-sectional study of 486 Japanese nondiabetic women, the relationship between the calculated insulin resistance (homeostasis model assessment ratio (HOMA-R)) and adiponectin levels determined using a validated sandwich ELISA. DESIGN AND METHODS: All participants were stratified into tertiles for HOMA-R (approximately <1.5, 1.5< or = approximately <3.0, 3.0< or = approximately ) and the differences across tertiles of continuous variables were tested with ANOVA. Two-way ANOVA was used to determine possible relationships for plasma adiponectin between tertiles of HOMA-R and several stratified parameters. Multiple regression analyses were performed with HOMA-R or fasting serum insulin as dependent variable, and diastolic blood pressure (BP), body mass index (BMI), serum triglyceride (TG), leptin and adiponectin as independent determinants. RESULTS: Mean plasma adiponectin in the high HOMA-R group decreased compared with that in the low HOMA-R group both before (mean+/-s.e.m. 6.2+/-0.6 vs 9.2+/-0.3 microg/ml, P<0.001) and after adjustment for body fat mass (BFM) as kg or percent (0.31+/-0.04 vs 0.69+/-0.03, 0.18+/-0.02 vs 0.34+/-0.01, both P<0.001). HOMA-R was inversely associated with adiponectin levels both before (r=-0.37, P<0.001) and after adjustment for BFM (r=-0.49, -0.46, both P<0.001). After covariate adjustment for age, diastolic BP, BMI and serum TG, HOMA-R retained a significant correlation with adiponectin/BFM (kg). Both adiponectin and leptin were the significant determinants of HOMA-R or fasting insulin in multiple regression models. CONCLUSIONS: Adiponectin was inversely associated with insulin resistance in nondiabetic subjects, independently from age, BP, adiposity and serum lipids. Because adiponectin is thought to have an anti-atherogenic action, the presence of hypoadiponectinemia may predispose subjects to atherosclerosis, and may progress the atherogenesis in insulin resistance.     

Waist circumference and waist-to-hip ratio in Turkish adults: interrelation with other risk factors and association with cardiovascular disease.

OBJECTIVE: To investigate the distribution of waist circumference (WC) and waist-to-hip ratio (WHR), their relationships with a number of established risk factors and their relevance to cardiovascular morbidity in a random sample of Turkish general adult population. DESIGN: Cross-sectional population-based study. Subjects: The subjects comprised 958 men and 1014 women, aged 25-74 years. MEASUREMENTS: Waist circumference was measured midway between the lower rib and iliac crest while that of the hip at the level of trochanters. Mean of two blood pressure measurements was used for analysis. Plasma total cholesterol (Cho) and triglyceride (Trg) concentrations were measured by the enzymatic dry method with a Reflotron apparatus. RESULTS: Overall mean WC measured 93+/-12 cm in men, and 88.6+/-13 cm in women. Mean WHR was 0.919+/-0.077 and 0.823+/-0.074, respectively, and a rise by about 0.001 was associated with each year of age. In multiple regression analysis a model was utilized that included age, body mass index (BMI), systolic and diastolic blood pressure (BP), plasma total Cho and Trg and category of smoking. This revealed age, BMI, and Trg as independent determinants of WHR in both genders, and diastolic BP in women alone. Age, BMI, and diastolic BP proved to be independently associated with WC in both genders, while Cho did so in men alone, Trg and systolic BP in women alone. Partial correlation coefficients on univariate analysis between all four variables of blood pressure and plasma lipids and either WC or WHR, controlled for age, were highly significant though moderately weak in both genders. These were stronger in men than in women, and stronger with respect to WC than to WHR. Cigarette smoking men and women had significantly lower WC or WHR than nonsmokers and ex-smokers, though these associations did not prove to be independent. When the relevance of WC and WHR to CHD risk was tested in this cohort (for the age bracket 45-74 years) comprising 138 cases with a clinical diagnosis of CHD, only WHR in women proved to be significantly associated. Odds ratio for a value of >0.845 was 1.6. CONCLUSION: WC and WHR are strongly associated with BMI and age as well as with parameters reflecting insulin resistance such as diastolic blood pressure and plasma triglycerides. WHR was significantly associated with coronary heart disease in Turkish women.     

Plasma leptin levels after biliopancreatic diversion: dissociation with body mass index.

Human obesity is associated with increased leptin levels, related to body composition and fat mass (FM). Insulin has been suggested to be a regulator of in vivo leptin secretion. To further investigate the relationships between insulin and leptin levels in human obesity, we have studied 10 obese females, aged 26-57 yr [body mass index (BMI), 42.9+/-6.3], successfully treated by biliopancreatic (BPD) diversion, in an early postoperative period (2 months after surgery, post-BPD I; BMI, 37.2+/-7.5) and a late postoperative period (16-24 months after surgery; BMI, 27.6+/-3.96). Fourteen normal female subjects (18-59 yr; BMI, 27.9+/-1.4 kg/m2) were studied as controls. In pre-BPD obese subjects, leptin levels were higher than those in controls (60.5+/-18.8 vs. 28.7+/-4.8 ng/mL; P<0.001). BMI and insulin levels were also significantly greater (P<0.0001 and P<0.03, respectively). After surgery, the three parameters considered significantly decreased (P = 0.0007 for BMI, P<0.0001 for leptin, and P = 0.038 for insulin, using Friedman's test for repeated data). Concerning the correlation between leptin and FM in our patients, control subjects and pre-BPD subjects confirmed the correlation found in the general population (r = 0.78; P<0.01). On the contrary, post-BPD patients at 2 months lay outside the general correlation between FM and leptin; in fact, patients with low leptin levels still had a high FM. Moreover, in the post-BPD patients there was no longer a significant correlation between FM and leptin. Concerning the correlation between insulin and leptin levels, a significant correlation was present in control subjects and pre-BPD patients (r = 0.46; P<0.05). Using correlation analysis for repeated measures in surgically treated obese patients, a significant correlation within the subjects was present (r = 0.91; P<0.0001). After operation, BMI and leptin levels had a different pattern of decrease; leptin decreased rapidly, without correlation with BMI, indicating that body composition is not the only factor regulating leptin levels. The consistent correlation with insulin levels suggests an important interaction between these two hormones in post-BPD obese subjects.     

Anthropometric, hormonal and biochemical differences in lean and obese women before and after menopause

The menopausal status is associated with an increased risk of metabolic and cardiovascular diseases. Since the post-menopausal modifications have not been clearly investigated in obese women, we evaluated the influences of menopausal status on anthropometric, hormonal and biochemical characteristics in selected groups of normal-weight and obese women. We studied 92 female outpatients: 24 normal-weight pre-menopausal (Pre-NW) [body mass index (BMI) 23.6 +/- 0.48, age 44.8 +/- 0.68], 24 normal-weight post-menopausal (Post-NW) (BMI 23.7 +/- 0.44, age 55.5 +/- 0.69), 24 obese pre-menopausal (pre-OB) (BMI 32.3 +/- 0.45, age 44.6 +/- 0.75), 20 obese post-menopausal women (Post-OB) (BMI 32.9 +/- 0.57, age 55.2 +/- 0.82). All the subjects were non smokers and free from hypertension, diabetes or impaired glucose tolerance (IGT). Anthropometric parameters, body composition, 17 beta-estradiol, LH, FSH, androstenedione, SHBG, testosterone and leptin were determined. Free androgen index (FAI) and insulin resistance index (HOMA) were calculated. In comparison with Pre-OB, Post-OB had higher values of waist circumferences (p < 0.02), while Post-NW showed no difference. Total and LDL-cholesterol were high in Post-NW women, whereas in the obese subjects they were already elevated in the premenopausal period. SHBG levels declined and FAI increased in Post-OB in comparison with Pre-OB. SHBG levels showed an inverse correlation with BMI, waist and waist-to-hip ratio (WHR), while FAI positively correlated with waist values. Serum leptin levels were higher in Post-OB than in Pre-OB, whereas they were similar in normal-weight women. The rise of leptin levels may be related to the greater abdominal fat deposition. In addition, menopausal status of uncomplicated obese women is associated with a greater abdominal fat deposition and with higher values of free androgen index, which may be considered as factors of cardiovascular risk.     

Plasma insulin concentration is more tightly linked to plasma leptin concentration than is the body mass index

This study tested the hypothesis that the integrated plasma insulin response to oral glucose is a more sensitive predictor of the fasting plasma leptin concentration than the body mass index (BMI) or waist to hip ratio (WHR). For this purpose, we determined the fasting plasma leptin concentration and plasma insulin response to a 75-g oral glucose challenge in 76 healthy female subjects, with a BMI of 19.1 to 36.6 kg/m2 and a WHR of 0.57 to 1.1. The results demonstrated that fasting plasma leptin concentrations were significantly correlated with both the BMI (r = .64, P < .001) and the plasma insulin response to glucose (r = .61, P < .001), but not with the WHR (r = .27). Since the BMI and the insulin response were also significantly related (r = .34, P = .003), multivariate analysis was performed to determine if the BMI and insulin response were independent determinants of the fasting leptin concentration. This analysis indicated that both the BMI and insulin response were significantly related to plasma leptin (P < .001). To pursue this issue further, the population was divided into tertiles on the basis of the (1) plasma leptin concentration, (2) BMI, and (3) integrated insulin response. The two variables that were most closely linked to each other were the leptin concentration and insulin response. In contrast, the BMI was relatively easily disassociated from the other two variables. These results indicate that while both the plasma insulin response to glucose and the BMI are significantly associated with the fasting plasma leptin concentration, the plasma insulin response appears more closely associated with the plasma leptin concentration.     

Serum leptin in formerly small-for-gestational-age children during adolescence: relationship to gender, puberty, body composition, insulin sensitivity, creatinine, and serum uric acid

Serum leptin levels reflect body fat mass (FM), and have been described to be related to serum uric acid levels in adult type 2 diabetic and healthy subjects. We therefore aimed to evaluate the interrelationship between leptin and markers of the metabolic syndrome by studying serum leptin concentration, body mass index (BMI), percent body fat (Fat%), total fat mass (FM), sum of skinfolds (SS), triglycerides (TG), total cholesterol (CHOL), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), glucose, insulin, calculated insulin resistance (HOMA), creatinine (CR), and uric acid (UA) concentration in 50 former small-for-gestational-age (SGA) children and 21 infants born adequate for gestational age (AGA) at the time of mid-puberty. Our data confirm previous results showing a positive association between leptin and body fatness, and female gender. Twelve children with impaired glucose tolerance (IGT) had higher UA levels than subjects with normal glucose tolerance (NGT) (5.1 +/- 1.1 v 4.2 +/- 1.2 mg/dL, P <.05), and showed the strongest relation between serum leptin and UA (r =.76, P <.001). Multiple regression analyses demonstrated that gender, estimates of total body adiposity (Fat% and SS), birth weight (BW), gestational age (GA), stimulated glucose and insulin, and serum UA are independently associated with serum leptin concentration in former SGA children with dysglycemia (R(2) =.89, P <.001). A long-term effect of intrauterine growth restriction on body fatness, metabolic syndrome, and serum leptin levels is suggested.