Insulin resistance and its association with the components of the metabolic syndrome among obese children and adolescents

Biological correlates and predictors of insulin resistance among early adolescents

Abnormal glucose metabolism is associated with obesity, insulin resistance (IR), and Type 2 diabetes mellitus. The purposes of this study were to describe anthropometric and laboratory markers of adolescents, examine correlates of IR, and test ability of anthropometric and laboratory markers to predict risk of exhibiting IR. A total of 150 early adolescents participated. Participants with obesity had increased IR, high-sensitivity C-reactive protein, triglycerides, and blood pressure. Waist circumference and triglycerides were predictive of IR. Multiple risk factors compound and lead to long-term health consequences among youth. Nurses can evaluate these factors to identify IR.

A proposed cutoff point of waist-to-height ratio for metabolic risk in African township adolescents

OBJECTIVE

A waist:height ratio (WHtR) higher than 0.5 has been proposed as a cutoff point for abdominal obesity in both sexes and at all ages. It is unknown if this cutoff point is appropriate for previously undernourished adolescents. We assessed the cutoff value of the WHtR associated with an increased metabolic risk in 178 black South African 14- to 18-y-old adolescents (69 boys, 109 girls).

METHODS

We measured weight, height, waist circumference, fasting plasma glucose and insulin levels, serum high-sensitivity C-reactive protein, and blood pressure and calculated the WHtR and homeostasis model assessment of insulin resistance (HOMA-IR). Using receiver operating characteristics curve analyses, we assessed the WHtR with the highest sensitivity and specificity to discriminate adolescents with increased fasting plasma glucose, HOMA-IR, serum high-sensitivity C-reactive protein, and blood pressure from those with "normal" values.

RESULTS

The WHtR cutoff points derived from the receiver operating characteristics curves ranged from 0.40 to 0.41, with best diagnostic value at 0.41. A WHtR of 0.40 had 80% sensitivity and 38.5% specificity to classify adolescents with fasting blood glucose level higher than 5.6 mmol/L (area under the curve [AUC] 0.57). A WHtR of 0.41 had 64% sensitivity and 58.5% specificity for a HOMA-IR higher than 3.4 (AUC 0.66), 55% sensitivity and 55.6% specificity for a high-sensitivity C-reactive protein level higher than 1 mg/L (AUC 0.57), and 64% sensitivity and 50.2% specificity for a blood pressure higher than the age-, sex-, and height-specific 90th percentiles (AUC 0.56). Adolescents with a WHtR higher than 0.41 had an odds ratio of 2.46 (95% confidence interval 0.96-6.30) for having a HOMA-IR higher than 3.4.

CONCLUSION

The WHtR cutoff to indicate metabolic risk for black South African adolescents is 0.41, which is lower than the proposed international cutoff of 0.5. The WHtR can be used for screening adolescents with components of the metabolic syndrome in intervention programs.

Obesity is associated with insulin resistance and components of the metabolic syndrome in Lebanese adolescents

Background

Prevalence of metabolic syndrome (MS) in obese adolescents has been reported to range between 18–42%, depending on country of origin, thus suggesting an ethnic-based association between obesity and MS.

Aim

This study aims to investigate the magnitude of the association between obesity, insulin resistance and components of MS among adolescents in Lebanon.

Subjects and methods

The sample included 263 adolescents at 4^th and 5^th Tanner stages of puberty (104 obese; 78 overweight; 81 normal weight). Anthropometric, biochemical and blood pressure measurements were performed. Body fat was assessed using dual-energy X-ray absorptiometry.

Results

According to International Diabetes Federation criteria, MS was identified in 21.2% of obese, 3.8% of overweight and 1.2% of normal weight subjects. The most common metabolic abnormalities among subjects having MS were elevated waist circumference (96.2%), low HDL (96.2%) and hypertriglyceridemia (73.1%). Insulin resistance was identified in all subjects having MS. Regression analyses showed that percentage body fat, waist circumference and BMI were similar in their ability to predict the MS in this age group.

Conclusions

MS was identified in a substantial proportion of Lebanese obese adolescents, thus highlighting the importance of early screening for obesity-associated metabolic abnormalities and of developing successful multi-component interventions addressing adolescent obesity.

The effectiveness of a primary care-based pediatric obesity program

The objective of this retrospective cohort study was to evaluate the effectiveness of the Duke University Healthy Lifestyles Program (HLP), a primary care-based childhood obesity treatment program. The study population included obese 2- through 19-year-old patients who entered the HLP between October 2006 through December 2008 and who had a visit to the HLP between the sixth and eighth month after entry. Most of the 282 patients were female (57%) and non-Hispanic/non-White (61%). The median age was 11 years. At baseline, the mean body mass index standard deviation score (BMI SDS) was 2.51, and patients achieved a mean reduction in BMI SDS of 0.10 (standard deviation = 0.20). For patients with baseline and follow-up measures of comorbidities, there were improvements in blood pressure, triglycerides, total cholesterol, and insulin resistance (P < .05). The patients in our obesity program demonstrated a small reduction in the severity of obesity. Improvements occurred in some obesity-associated comorbidities.

rs12255372 variant of TCF7L2 gene is protective for obesity in Mexican children

BACKGROUND AND AIMS

Variants in the transcription factor 7-like 2 (TCF7L2) gene are consistently associated with type 2 diabetes in adults, but the association of TCF7L2 with weight-related traits and body fat in humans is unclear. The aim of this study was to determine the relationship between the TCF7L2 gene (rs12255372) and obese phenotype in Mexican school-age children.

METHODS

The study was performed in schools in Mexico City; 186 obese and 194 control children were studied. Fasting insulin and glucose, total cholesterol, LDL-C, HDL-C and triglycerides concentration were determined. The variant rs12255372 of the TCF7L2 gene was genotyped. We used age- and sex-adjusted linear models to test for association with metabolic measurements with this variant.

RESULTS

Genotype of the TCF7L2 rs12255372 gene was associated with lower fasting plasma glucose (p = 0.001) and lower homeostasis model assessment of insulin resistance (HOMA-R; p = 0.001) in nonobese children. Heterozygous carriers for this variant were more prevalent in lean children (32.5%) than in the obese group (23.7%), which resulted in a strong protective effect for the normal weight condition (OR = 0.56, 0.32-0.97).

CONCLUSIONS

TCF7L2 rs12255372 polymorphism protects Mexican children from obesity. Further research in other large, population-based studies is needed to replicate these findings.

An after-school dance and lifestyle education program reduces risk factors for heart disease and diabetes in elementary school children

BACKGROUND

Forty-three percent of New York City's (NYC) school-age children are overweight or obese, placing them at risk for heart disease and type 2 diabetes mellitus (T2DM).

OBJECTIVE

The objective of this study was to determine if an intensive after-school dance and lifestyle education program would reduce risk factors for heart disease, T2DM, and improve lifestyle choices.

SUBJECTS

Subject include 64 fourth- and fifth-grade students at an elementary school in NYC.

METHODS

Students received freestyle dance and lifestyle classes for 16 weeks and were evaluated for changes in body composition, endurance, biochemical measurements, and lifestyle choices.

RESULTS

Significant improvements in BMI percentiles were found among children in the overweight and obese categories as well as in endurance and biochemical measurements that reflect heart disease and diabetes risk. Improvement was also reported in lifestyle choices.

CONCLUSION

An intensive after-school dance and lifestyle education program can reduce risk factors for heart disease and T2DM and improve lifestyle choices among elementary school children.

Optimal cutoff points for body mass index, waist circumference and HOMA-IR to identify a cluster of cardiometabolic abnormalities in normal glucose-tolerant Brazilian children and adolescents

OBJECTIVE: The aim of this study was to establish the best cutoff values for waist circumference (WC), body mass index (BMI) and HOMA-IR (HR) to identify a cluster (> 3) of cardiovascular risk factors (CVRF) in normal glucose-tolerant (NGT) Brazilian children and adolescents. SUBJECTS AND METHODS: Cross-sectional study of 319 individuals (aged 10 to 19y) from a southern Brazilian city. Gender-specific receiver-operating characteristics (ROC) curves were constructed to assess cutoffs values of BMI (kg/m², WC (cm), and HR. RESULTS: The areas under the ROC curves to detect a cluster of CVRF were 0.92, 0.93 and 0.68 (females), and 0.93, 0.93 and 0.89 (males), for WC, BMI and HR, respectively. The cutoff values were 83.0 and 80.5 cm (WC), 22.7 and 20.4 kg/m2 (BMI), and 1.65 and 1.95 (HR), for females and males, respectively, to detect the cluster of CVRF. CONCLUSION: These values of BMI, WC-) and (HR) detected a high proportion of NGTt Brazilian children and adolescents with a cluster of CVRF.

Waist circumference values according to height percentiles: a proposal to evaluate abdominal obesity in Mexican children and adolescents between 6 and 16 years of age

BACKGROUND AND AIMS

Waist circumference (WC) is a good anthropometric indicator for diagnosing abdominal obesity across different age groups, including children and adolescents. It is unknown whether height may modify this indicator independent of other variables such as age, gender and ethnicity. We undertook this study to determine whether WC of children and adolescents shows variations in size according to height percentiles and propose these values as reference to assess abdominal obesity in children.

METHODS

We carried out a cross-sectional analytical study in which weight, height and WC were measured in children and adolescents attending elementary schools in Mexico City. Included in the study were 3378 individuals between 6 and 16 years of age. Using quantile regression, estimated values of WC were obtained according to age and gender for the following percentiles of height: 10(th), 25(th), 50(th), 75(th) and 90(th). Likewise, for each of these height percentiles, the following percentiles of WC were calculated: 50(th), 75(th) and 90(th).

RESULTS

Among males, WC values increased 2.0 cm for ten units of height percentiles and 2.5 cm for each year of age. Among females, WC increased 1.0 cm and 2.8 cm, respectively. WC values of individuals of the same age and gender in the lower height percentiles were less than those of individuals in the upper height percentiles.

CONCLUSIONS

WC demonstrates variations directly associated with height percentiles.

Association between Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) and Components of Metabolic Syndrome in Young Chinese Men

BACKGROUND

To investigate the prevalence of metabolic syndrome (MetS) in young Chinese population and assess the association between HOMA-IR and different components of MetS in young Chinese men.

METHODS

Overall 5576 young Chinese subjects (age range [19-44 yr], 3636 men) were enrolled in, who visited our Health Care Center for a related health checkup from March to December 2008. The international diabetes federation (IDF) definition for MetS was used. The SPSS statistical package, version 11.5 was used for the statistical analysis.

RESULTS

The prevalence of MetS was 21.81% in young men and 5.62% in young women. According to suffering from different numbers of MetS components, the male subjects were divided into four groups. Numbers of MetS components were more and HOMA-IR values were significantly higher. In this male population, the quartile of HOMA-IR was higher, values of triglyceride (TG), fasting plasma glucose (FBG), systolic blood pressure(SBP), diastolic blood pressure(DBP) and waist circumference (WC) were all significantly higher, as well as high density lipoprotein cholesterol (HDL-C) value was significantly lower (P= 0.000). In Spearman's correlation analysis, HOMA-IR was positively correlated with TG, FBG, SBP, DBP and WC, and negatively correlated with HDL-C (r= 0.460, 0.464, 0.362, 0.346, 0.586, -0.357, respectively, all P value= 0.000).

CONCLUSION

The prevalence of MetS in these young Chinese men was obviously high. Insulin resistance played an important role in occurrence and development of MetS. Waist circumference was the best correlation with HOMA-IR among all components of MetS.