Anthropometric predictors of serum fasting insulin in 9- and 15-year-old children and adolescents

Obesity and Insulin Resistance Screening Tools in American Adolescents: National Health and Nutrition Examination Survey (NHANES) 1999 to 2010

OBJECTIVE

To identify which feasible obesity and insulin resistance (IR) screening tools are most strongly associated in adolescents by using a nationally representative sample.

METHODS

Adolescents aged 12.0 to 18.9 years who were participating in the National Health and Nutrition Examination Survey (NHANES) (n=3584) and who were measured for height, weight, waist circumference (WC), triceps and subscapular skinfold thickness, glycated hemoglobin, fasting glucose (FG) and fasting insulin (FI) level were included. Adolescents were split by gender and grouped by body mass index (BMI) percentile. Age- and gender-specific classifications were constructed for each obesity screening tool measure to account for growth and maturation. General linear models were used to establish groups objectively for analysis based on when IR began to increase. Additional general linear models were used to identify when IR significantly increased for each IR measure as obesity group increased and to identify the variance accounted for among each obesity-IR screening tool relationship.

RESULTS

As the obesity group increased, homeostasis model assessment-insulin resistance (HOMA-IR) and FI significantly increased, while FG increased only (above the referent) in groups with BMI percentiles ≥95.0, and glycated hemoglobin level did not vary across obesity groups. The most strongly associated screening tools were WC and FI in boys (R(2)=0.253) and girls (R(2)=0.257). FI had the strongest association with all of the obesity measures. BMI associations were slightly weaker than WC in each in relation to IR.

CONCLUSIONS

Our findings show that WC and FI are the most strongly associated obesity and IR screening tool measures in adolescents. These feasible screening tools should be utilized in screening practices for at-risk adolescents.

A matter of fat: insulin resistance and oxidative stress

BACKGROUND

Obesity is linked to insulin resistance (IR), which can lead to type 2 diabetes mellitus. Oxidative stress present in early obesity may favor the progression to comorbid conditions.

OBJECTIVE

To examine the relationship between oxidative stress biomarkers and the severity of IR in a group of obese children.

METHODS

Forty obese children with a body mass index (BMI) Z-score ≥ 2 were divided into two groups using the median obtained for the homeostasis model assessment of IR (HOMA-IR). Anthropometric parameters (including body fat composition by bioelectrical impedance) and biochemical parameters were assessed. The following biomarkers of oxidative stress were measured: malondialdehyde (MDA), carbonyl groups (CG), reduced glutathione, oxidized low-density lipoprotein, and vitamin E. Comparisons were adjusted for gender and Tanner stage.

RESULTS

Children with high values of HOMA-IR were more likely to have high body fat percentage and waist circumferences. However, the BMI Z-score did not correlate to the level of IR. Children with higher values of HOMA-IR presented increased levels of markers of oxidative stress in lipids (MDA, p = 0.005) and proteins (CG, p = 0.015). Moreover, MDA increased with increasing levels of HOMA-IR (r = 0.50, p = 0.002), suggesting that lipoperoxidation increases as IR worsens. In a multivariate regression model, only HOMA-IR was predictive of MDA values, irrespective of adiposity parameters and other metabolic risk factors (r2 = 0.22, p = 0.002).

CONCLUSIONS

Oxidative stress increases in obese children according to the severity of IR, which could be linked to the development of comorbidities.

Comparison of several anthropometric indices with insulin resistance proxy measures among European adolescents: The Helena Study

The aim of the current study was to compare the association of several anthropometric indices, with insulin resistance (IR) proxy measures in European adolescents. The present study comprises 1,097 adolescents aged 12.5-17.5 from ten European cities participating in the HELENA study. Weight, height, waist circumference (WC) and hip circumference, skinfolds thickness, fat mass (FM), fasting plasma glucose (G(F)) and serum insulin (I(F)) levels were measured. HOMA (as indicator of IR body mass index (BMI), waist to hip ratio (WHR) and waist to height ratio (WHtR) were calculated. I(F) and HOMA were statistically significantly related to BMI, WC, skinfold sum, WHtR, WHR and FM. BMI, WC, WHtR, skinfold sum and FM displayed similar correlation with I(F) and HOMA as opposed to WHR where lower correlation with IR indices was detected in the overall sample. Similar results were found for boys, girls and underweight/normal weight adolescents. On the other hand, WC and WHtR were found to be more strongly associated with IR proxy measures compared to the rest of anthropometric indices among overweight/obese subjects. Based on the current findings, WC and WHtR could be used, alternatively, to identify the overweight/obese adolescent at risk for developing IR. In addition, all aforementioned anthropometric indices, except WHR, could be used among the underweight/normal weight adolescents.

Associations between insulin and glucose concentrations and anthropometric measures of fat mass in Australian adolescents

BACKGROUND

One of the most serious, yet common co-morbidities of obesity is insulin resistance, which if untreated may progress to type 2 diabetes. This paper describes the insulin and glucose concentration distributions, the prevalence of elevated insulin, the associations between insulin and body mass index (BMI), waist circumference, waist-to-height ratio (WHtR) and fat mass index in a representative sample of Australian adolescents.

METHODS

Cross-sectional population-based study of adolescent boys and girls (N = 496, mean age 15.3 years) attending schools in metropolitan Sydney, Australia. Fasting venous blood collected and analysed for insulin and glucose concentrations. Height, weight, waist circumference measured, BMI and waist-to-height ratio calculated. Pubertal status self-reported.

RESULTS

Glucose concentrations were normally distributed and were not associated with adiposity. Insulin concentrations were distributed logarithmically, were higher among girls than boys overall and within the same ranges of BMI and waist circumference, but were lower among girls than boys within the same ranges of fat mass adjusted for height. The prevalence of elevated insulin concentration (defined as > 100 pmol/L) was 15.9% and 17.1% among boys and girls, respectively. Correlations between insulin concentration and BMI, waist circumference, WHtR and fat mass adjusted for height were 0.53, 0.49, 0.51 and 0.55, among boys, respectively, and 0.35, 0.40, 0.42 and 0.34, among girls, respectively.

CONCLUSIONS

Elevated insulin is highly correlated with adiposity in adolescents. BMI and WHtR are simple measures that can be used to identify young people who should be screened for insulin resistance and other co-morbidities.

Metabolic profiles of fat and glucose differ by gender in healthy 8-year-olds

OBJECTIVE

The aim was to investigate if metabolic markers were associated with anthropometry and weight increase in healthy 8-year-olds.

METHODS

Ninety-seven healthy children, 66 of whom had been examined at the age of 4 years, were investigated. Dual energy X-ray absorptiometry was performed to determine fat (FM) and lean body mass (LBM). Plasma glucose and serum levels of insulin, cholesterol, triglycerides, adiponectin and leptin were analysed and HOMA-indices were calculated.

RESULTS

Despite similar anthropometry, metabolic markers differed by gender. Sixteen % of the children were overweight or obese. Body mass index (BMI) was strongly correlated to FM. Anthropometric measures except LBM correlated to metabolic markers in the girls. Boys had higher concentrations of plasma glucose than girls. In overweight children, insulin was negatively associated with LBM. Leptin and the ratio between leptin and adiponectin, but not adiponectin, were significantly associated with HOMA-IR and body composition.

CONCLUSION

The metabolic profile of plasma glucose, serum leptin, fasting insulin and related HOMA indices differed by gender, despite no difference in BMI or FM. LBM, but not FM correlated to the insulin concentration in the overweight children. Leptin was the best marker of overweight.

The Relationship between Changes in Weight Status and Insulin Resistance in Youth

This study examined changes in insulin resistance (IR) in 120 youth over two years. IR was quantified via homeostatic model (HOMA-IR), and weight status changes were quantified via body mass index (BMI). When all participants were considered, the mean HOMA-IR and BMI increased 13.4% and 1.65 units, respectively. Change in BMI z-score and percent change in HOMA-IR were moderately associated (r = 0.39). Follow-up analyses were performed for the following weight groups: NN (normal at baseline and two years later), NO (normal to overweight), ON (overweight to normal), and OO (overweight at both points). The NO group had a greater change in HOMA-IR (+50%) compared to other groups: ON (-8%), NN (+2%), and OO (-0.1%) (P < .05). The association between changes in BMI z-score and HOMA-IR was r = 0.49 when only the NO and ON groups were included. These results reinforce the importance of preventing youth from becoming overweight to control IR.

Association of BMI and fasting insulin with cardiovascular disease risk factors in seven-year-old Icelandic children

OBJECTIVE

. To look at overweight and common cardiovascular disease (CVD) risk factors, and associations with body mass index (BMI) and fasting insulin in seven-year-old schoolchildren in Reykjavik, Iceland.

STUDY DESIGN

Cross-sectional study of seven-year-old schoolchildren.

SETTING

Six elementary schools in Reykjavik.

SUBJECTS

All children attending second grade in these six schools were invited to participate.

MAIN OUTCOME MEASURES

Overweight, fasting serum insulin, CVD risk factors.

RESULTS

Some 14% of the participating children were classified as overweight. Overweight children had higher fasting insulin, higher fasting glucose, and higher systolic and diastolic blood pressure. Furthermore, they had significantly lower total cholesterol (TC), lower high-density lipoprotein (HDL), and lower low-density lipoprotein (LDL) but a similar TC/LDL ratio to normal-weight children. The factors that were strongly associated with BMI were serum fasting insulin, systolic blood pressure (SBP), HDL and fasting glucose, while the sum of four skinfolds, triglycerides, glucose, and LDL were highly associated with fasting insulin.

CONCLUSION

Overweight children are likelier to have unfavourable levels of common CVD risk factors included in metabolic syndrome, but surprisingly had lower LDL and TC. Skinfold thickness, higher triglyceride and glucose levels, and being female were associated with increased serum insulin.

Associations of several anthropometric indices with insulin resistance in children: The Children Study

AIM

To compare the associations of several anthropometric indices (i.e. waist circumference [WC], waist-to-height ratio, body mass index (BMI) and waist-to-hip ratio) with the insulin resistance (IR) proxy measures in Greek schoolchildren.

METHODS

A random sample of 248 children was used. Fasting plasma glucose and serum insulin levels were measured. IR was estimated through homeostasis model assessment (HOMA), glucose-to-insulin ratio and quantitative insulin sensitivity check index.

RESULTS

Insulin levels and IR indices were significantly related to BMI, WC and waist-to-height ratio. Glucose-to-insulin ratio and quantitative insulin sensitivity check index were inversely correlated with all anthropometric indices, while insulin levels and HOMA were positively associated with these indices. Generally, all significant correlations were weak to moderate (0.217 <or= r <or= 0.513). BMI, WC and waist-to-height ratio displayed similar correlation with insulin levels (r=0.431, r=0.427 and r=0.354, respectively) and IR indices. Similar results were found using multiple linear regression analysis.

CONCLUSION

Based on the current findings, BMI, waist-to-height ratio and WC are higher, associated with the IR proxy measures compared with waist-to-hip ratio, among Greek pupils. Therefore, all these simple adiposity-related indices could be used, alternatively, in clinical practice as a simple tool for identification of children at risk for developing IR.

Understanding and preventing childhood obesity and related disorders--IDEFICS: a European multilevel epidemiological approach

The environment of children has drastically changed in Europe during the last decades as reflected in unhealthy dietary habits and sedentary lifestyle. Nutrition obviously plays a part in the development of overweight in childhood. However, dietary factors and physical activity are also involved in the development of metabolic syndrome, type II diabetes, cardiovascular diseases, osteoporosis, and postural deformities like scoliosis, effects related in part to excessive weight gain. To stop the resulting epidemic of diet- and lifestyle-induced morbidity, efficient evidence-based approaches are needed. These issues are the focus of IDEFICS (Identification and prevention of dietary- and lifestyle-induced health effects in children and infants), a five-year project proposed under the sixth EU framework. The IDEFICS consortium comprises 25 research centres and SMEs across Europe. The planned prospective study will identify risk profile inventories for children susceptible to any of these disorders with emphasis on obesity and its co-morbid conditions. Genetic and non-genetic factors, psychosocial factors and social settings will be considered. The project will devise tailored prevention strategies that are effective, easy to implement and that account for the needs of different social groups. Population-based studies will investigate the impact of sensory perception and provide results concerning internal and external triggers of food choices and children's consumer behaviour. The ethical implications of a "right not to know" of genetic factors will be addressed. We will propose knowledge-based guidelines on dietary and lifestyle activities for health promotion and disease prevention in children for health professionals, stakeholders and consumers.