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Abstract: Irisin, a novel myokine, is believed to be the crucial factor in converting white adipose tissue to beige adipose tissue. For this paper, we studied the relationship among irisin and components of metabolic syndrome (MetS), and insulin secretion and resistance in schoolchildren of Taiwan.Subjects receiving routine annual health examination at elementary school were enrolled. Demographic data, anthropometry, MetS components, irisin, and insulin secretion and resistance were collected. Subjects were divided into normal, overweight, and obese groups for evaluation of irisin in obesity. Finally, the relationship between irisin and MetS was analyzed.There were 376 children (179 boys and 197 girls), aged 10.3 ± 1.5 years, were enrolled. In boys, irisin levels were not associated with body mass index percentile, body fat, blood pressure, lipid profiles, insulin secretion or resistance. After adjusting for age, the irisin level in boys was negatively related to fasting plasma glucose (FPG) (r = -0.21, P = .006). In girls, after adjusting for age, the irisin levels were positively related only to FPG (r = 1.49, P = .038). In both genders, irisin levels were similar among normal, overweight, and obese groups, and between subjects with and without MetS.The irisin levels were not associated with MetS in either boys or girls. In girls, circulating irisin levels have a nonsignificant declining trend in overweight and obese girls. However, irisin levels were negatively related to FPG in boys and positively related to FPG in girls. The contrary relationship between irisin and FPG in boys and girls needs further exploration., Competing Interests: The authors report no conflicts of interest., (Copyright © 2021 the Author(s). Published by Wolters Kluwer Health, Inc.)

Objective: Adiponectin, a novel adipokine with antiinflammatory and insulin-sensitizing properties, has an important role in glucose metabolism and is negatively correlated with body fat amount in adults. The purpose of this study was to evaluate the association of plasma adiponectin level with metabolic risk profiles and insulin resistance status among Taiwanese children., Research Methods and Procedures: We enrolled 1,248 children (608 boys and 640 girls) to ascertain their demographic, anthropometric, and cardiovascular risk factors distribution in Taipei. We measured plasma insulin, adiponectin, and leptin levels by radioimmunoassay (Linco Research Inc, St. Charles, MO). We calculated an insulin resistance index (IRI) using the Homeostasis Model Assessment model and also calculated an insulin resistance syndrome (IRS) summary score for each individual by adding the quartile ranks from the distribution of systolic blood pressure, serum triglyceride, high-density lipoprotein-cholesterol (HDL-C) (inverse), and insulin levels., Results: In general, the boys had larger BMI, higher systolic blood pressure, serum total cholesterol, and triglyceride, and lower plasma leptin and adiponectin levels than girls. Plasma adiponectin levels were correlated negatively with BMI, leptin, insulin, IRI, and IRS summary score but positively correlated with HDL-C in both boys and girls. In multivariate regression analyses, adiponectin was negatively associated with insulin (girls only), IRI (girls only), and IRS score, and positively associated with HDL-C in both genders even after adjusting for age, BMI, plasma leptin level, and other potential confounders., Discussion: These data suggest that plasma adiponectin levels were negatively associated with metabolic risk profiles that may have played a protective role in the development of insulin resistance among Taiwanese school children.

Purpose: Evidence suggests that there may be a metabolic syndrome characterized by hyperinsulinemia or insulin resistance associated with increased cardiovascular disease risk. The purpose of this study is to evaluate insulin, proinsulin or insulin resistance to determine which is the best parameter to predict lipid profiles among children in Taiwan., Methods: After multi-stage sampling, we randomly included 852 school children (415 boys and 437 girls) with a mean age of 13 yr in this study. We measured insulin and intact proinsulin levels by RIA (<0.2% cross-reactivity) and estimated insulin resistance index (IRI) using the homeostatic model assessment (HOMA) method. We used standard methods to measure atherosclerotic lipid profiles including total cholesterol (CHOL), triglyceride (TG), HDL-C, apolipoprotein A (ApoA), apolipoprotein B (ApoB), and lipoprotein[a] and calculated LDL-C and TCHR (total cholesterol to HDL-C ratio) levels., Results: Girls had higher CHOL, LDL-C, ApoA and ApoB levels than boys (p < 0.001). There was no significant difference in insulin, proinsulin and IRI status between boys and girls. Among boys, insulin, proinsulin and IRI were positively correlated with TG, ApoB and TCHR and negatively related to HDL-C. Among girls, these associations were attenuated and became insignificantly for TCHR and HDL-C. After adjusting for potential confounders, IRI and insulin were still positively associated with TG and ApoB levels and negatively associated with HDL-C in boys. However, in girls, proinsulin and insulin were positively associated with TG only. Finally, in the stepwise regression analyses, IRI was a better predictor of TG, HDL-C, and ApoB than insulin or proinsulin in boys. However, in girls, proinsulin was a stronger predictor than insulin or IRI for TG and TCHR., Conclusion: From this study, we found that IRI (in boys) and proinsulin (in girls) levels are generally more significant and stronger parameters than insulin for predicting lipid profiles among children in Taiwan.

Objective: Observational studies support inverse associations between moderate alcohol consumption and fasting insulin concentrations, but the importance of drinking pattern on the effect of alcohol on insulin sensitivity has not been fully explored. We examined the relations of alcohol consumption patterns-including average daily consumption, frequency of consumption and drinking with meals-to fasting insulin, fasting c-peptide and hemoglobin A1c (HbA1c)., Methods: A cross-sectional study of 462 disease-free men selected from the Health Professionals' Follow-up Study to provide information on a range of drinking patterns. Study participants were 48 to 82 years of age who provided a blood sample and detailed information on diet, life-style and alcohol consumption patterns in 1994. Among the study participants, 267 men provided a fasting blood sample and contributed to the analyses of insulin and c-peptide., Results: Biologic markers were not strongly related to average alcohol consumption. Compared to abstainers, differences in insulin concentrations-all statistically non-significant-were 0.06, 1.25, 1.02, and 0.12 micro U/mL for consumers of <1, 1-1.9, 2-2.9, 3+ drinks per day, respectively. The frequency of alcohol consumption was inversely related to fasting c-peptide and insulin concentrations after controlling for average alcohol consumption and other potential confounding variables. Compared to men who reported consuming alcohol one to three days per week, c-peptide concentrations were 0.08 ng/mL and 0.29 ng/mL lower (p-trend = 0.04) in men who reported consuming alcohol on four to five days per week and six to seven days per week, respectively. Men who consumed alcohol on most days also had lower fasting insulin levels than more irregular drinkers (p-trend = 0.05)., Conclusions: Our results suggest that frequent alcohol consumption is inversely related to fasting c-peptide and insulin concentrations.

Objectives: Leptin is a multifunctional polypeptide produced primarily by adipocytes and associated with the occurrence of obesity and insulin resistance. Tumor necrosis factor-alpha (TNF-alpha), a polypeptide cytokine produced primarily by mononuclear phagocytes, plays a key role in the initiation of the inflammatory response but has a multitude of effects in many tissues. The interactions between TNF-alpha and insulin on leptin expression are complicated and have not been completely described. The purpose of this study is to evaluate interactions between TNF-alpha and insulin on circulating leptin levels among normal and overweight children., Design and Methods: After multi-stage sampling, we randomly selected 1,500 school children in this survey. All children completed a questionnaire on their disease history and lifestyle characteristics. We measured body weight, height, waist and hip circumference of children and calculated BMI and Waist-to-hip ratio (WHR). We also measured plasma tumor necrosis factor-receptor 1 (TNF-R1) by ELISA, plasma insulin and circulating leptin levels by RIA using commercial kits. We divided the children into normal or overweight groups using BMI criteria (85th percentile) to evaluate the relationship of TNF-R1 and insulin on circulating leptin concentrations., Results: In general, boys were taller, heavier and had higher TNF-R1 and lower leptin levels than girls. Plasma leptin levels were positively correlated with anthropometric variables and insulin levels among children in both genders. In multivariate regression analyses, plasma insulin levels were significantly positive associated with leptin levels in normal weight children. Plasma TNF-R1 levels were positively associated with leptin levels even after adjusting for BMI in girls only., Conclusions: From this study, we found that plasma insulin plays certain role in leptin expression among normal weight children. However, TNF-R1 plays a more significant role in leptin expression among girls only.

Obesity is related to cardiovascular disease (CVD) morbidity and mortality, however, the mechanisms for the development of obesity-induced CVD risk remain unclear. Hyperinsulinemia and insulin resistance are considered key components in the metabolic cardiovascular syndrome and as independent risk factors for CVD. Plasma leptin and tumor necrosis factor-alpha (TNF-alpha), two adipocyte products, are also proposed to be associated with the development of CVD risk. The purpose of this study is to evaluate the association of plasma leptin, soluble TNF receptors (sTNF-R), and insulin levels as possible mediators of the effect of obesity on atherogenic and thrombogenic CVD risk factors among men. From the Health Professionals Follow-up Study (HPFS), we selected 268 men, aged 47--83 years, who were free of CVD, diabetes, and cancer (except non-melanoma skin cancer), and who had provided a fasting blood sample in 1994. We measured plasma insulin and leptin levels by radioimmunoassay and sTNF-R levels by ELISA. Men in the highest quintile of body mass index (BMI, mean=30.5 kg/m(2)) were less physically active and had a more adverse cardiovascular lipid and homeostatic profile, as indicated by levels of insulin, triglyceride (TG), tissue plasminogen activator (t-PA) antigen levels, and apolipoprotein A1 (Apo-A1). In a multivariate regression model controlling for age, smoking, alcohol intake, physical activity and diet, BMI was inversely associated with HDL-cholesterol (HDL-C) and Apo-A1 and positively associated with TG, Apo-B and t-PA antigen levels. The associations between BMI and these CVD risk factors were only slightly changed after adjusting for leptin and/or sTNF-R; but were substantially attenuated after controlling for insulin levels. These data suggest that the association between obesity and biological predictors of CVD may be mediated through changes in plasma insulin, rather than leptin or sTNF-R levels. However, plasma leptin may still play a role in CVD through independent effects on lipid metabolism.

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.