Indexes of insulin resistance and secretion in obese children and adolescents: a validation study

The metabolic inter-relationships between changes in waist circumference, triglycerides, insulin sensitivity and small, dense low-density lipoprotein particles with acute weight loss in clinically obese children and adolescents

OBJECTIVE

Small, dense low-density lipoprotein (LDL) particles are highly atherogenic and strongly associated with obesity-related dyslipidemia. The metabolic inter-relationships between weight loss induced changes in waist circumference, triglycerides, insulin sensitivity and small-dense LDL particles in clinically obese children and adolescents have not been studied.

METHODS

Seventy-five clinically obese boys and girls (standardized body mass index 3.07 ± 0.59, aged 8-18 years) were recruited. Anthropometric, body composition and cardiometabolic risk factors were measured pre- and post-weight loss.

RESULTS

There were highly significant reductions in anthropometric, body composition and cardiometabolic risk factors. Triglyceride change was positively correlated with LDL peak particle density and percentage LDL pattern B changes (relative abundance of small, dense LDL particles). Multiple regression analyses showed that changes in triglyceride concentration accounted for between 24 and 18% of the variance in LDL peak particle density and percentage LDL pattern B change, respectively. Changes in waist circumference and insulin sensitivity did not predict these changes in LDL characteristics.

CONCLUSION

Acute and highly significant weight loss significantly decreased LDL peak particle density and percentage LDL pattern B. The change in triglycerides was a strong predictor of LDL peak particle density and percentage LDL pattern B change.

Serum uric acid: relationships with biomarkers in adolescents and changes over 1 year

OBJECTIVES

To (1) elucidate the range of serum uric acid (UA) levels in adolescent sample; (2) examine the relationships of serum UA and 1-year change with gender, anthropometric and cardiometabolic factors.

MATERIALS AND METHODS

Measurements (anthropometrics, fasting venipuncture and blood pressure) were performed at the beginning of the seventh and eighth grades. Descriptive data, differences according to weight, correlations and changes over time were examined.

FINDINGS

In 77 adolescents, BMI and serum UA had relationships with several cardiometabolic measures. Males had higher serum UA at follow-up compared to baseline; female change was minimal. Time-by-gender interaction was significant, as were the main effects of gender and BMI classification. Males had lower HDL-C at follow-up than at baseline; females had higher HDL-C at follow-up.

CONCLUSIONS

Serum UA has importance in cardiometabolic examination of youth risk factors. It should be examined in youth with elevated BMI and/or hypertension. Early adolescence is the period when gender-related metabolic changes occur.

Use of a simple liquid meal test to evaluate insulin sensitivity and beta-cell function in children

Insulin sensitivity and β-cell function are useful indices of metabolic disease risk but are difficult to assess in young children because of the invasive nature of commonly used methodology. A meal-based method for assessing insulin sensitivity and β-cell function may at least partially alleviate concerns. The objectives of this study were to: (i) determine the association of insulin sensitivity assessed by liquid meal test with that determined by an insulin-modified frequently sampled intravenous glucose tolerance test (FSIGT); (ii) examine the association of insulin sensitivity derived from each test with measures of body composition, fat distribution and metabolic health (lipids, fasting insulin and glucose, and surrogate indices of insulin sensitivity); and (iii) examine the associations of indices of β-cell function derived from each test with total and regional adiposity. Forty-seven children (7-12 years) underwent both a liquid meal test and an FSIGT. The insulin sensitivity index derived from the meal test (SI-meal) was positively associated with that from the FSIGT (SI-FSIGT; r = 0.63; P < 0.001), and inversely with all measures of insulin secretion derived from the meal test. Both SI-meal and SI-FSIGT were associated with measures of total and regional adiposity. SI-meal, but not SI-FSIGT, was associated with triglycerides and fasting insulin, after adjusting for ethnicity, gender, pubertal stage and fat mass. Basal insulin secretion measured during the meal test was positively associated with all measures of adiposity, independent of insulin sensitivity. In conclusion, a liquid meal offers a valid and sensitive means of assessing insulin sensitivity and β-cell responsivity in young children.

Associations of birth weight and postnatal weight gain with cardiometabolic risk parameters at 5 years of age

The present prospective study assessed the impact of birth weight (BW) and postnatal weight gain on blood pressure and metabolic profile during the first 5 years of life. One hundred thirty-nine newborns (63 women) born at term after uncomplicated pregnancies and in the absence of perinatal illness were included. Subjects were divided according to size at birth in small, appropriate, and large for gestational age. After the initial evaluation on the second day of life, infants were followed up at 6 months and 2 and 5 years. Anthropometric parameters and blood pressure were measured at each visit and metabolic assessment was performed at 5 years of age. Among the BW groups, mothers did not differ in terms of age, smoking, and weight gain during pregnancy. BW was a positive determinant of systolic blood pressure at birth. Afterward, current weight was the strongest determinant, becoming significant at 2 years of age and progressively increasing in influence. At 5 years insulin, the homeostasis model assessment index and triglycerides were dependent on BW, current weight, and postnatal weight gain. In addition, BW was positively associated with high-density lipoprotein-cholesterol and inversely so to uric acid. A positive relationship among insulin, blood pressure values, and uric acid was observed even early in life. In conclusion, the acceleration of early infant weight gain may aggravate the effects of low BW. Multiple interactions between hemodynamic and metabolic parameters foreshadow the clustering of cardiometabolic risk factors later in life.

The relationship of oxidative stress, adiposity and metabolic risk factors in healthy Black and White American youth

What is already known about this subject African Americans are disproportionately affected by obesity and other metabolic risk factors in comparison to White Americans. Increasing prevalence of obesity has been associated with concomitant increases in childhood hypertension, dyslipidaemia and type 2 diabetes. Oxidative stress is associated with obesity in both adults and children. What this study adds Oxidative stress is positively associated with total body fat and truncal fat, but not with body mass index (BMI) or BMI z-score in healthy youth. Oxidative stress is associated with diastolic blood pressure in African American but not in White American healthy youth.

BACKGROUND

Oxidative stress is elevated in obese youth, but less is known regarding racial disparities in the relationship of oxidative stress with metabolic risk factors.

OBJECTIVES

To determine the relationship between oxidative stress and metabolic risk factors, adiposity, leptin, adiponectin and cardiovascular fitness (VO2PEAK ) in healthy African American and White American youth.

METHODS

A marker of oxidative stress (F2 -isoprostane), validated markers of metabolic risk factors, fitness and body composition were measured in African American (n = 82) and White American (n = 76) youth (8-17 years old) recruited over a range of BMI percentiles (4th to 99th).

RESULTS

F2 -isoprostane concentration was positively correlated with percentage body fat (r = 0.198) and percentage truncal fat (r = 0.173), but was not different between African American and White American males and females (P = 0.208). African American youth had significantly higher mean systolic and diastolic blood pressure (P = 0.023 and P = 0.011, respectively), body weight, BMI percentile and Tanner stage. After adjusting for gender, age, BMI and Tanner stage, African American youth varied from White Americans in the association of F2 -isoprostane with diastolic blood pressure (P = 0.047), but not with systolic blood pressure, triglycerides, VO2PEAK or homeostatic model assessment for insulin resistance (all P > 0.05).

CONCLUSIONS

Oxidative stress, as measured by urinary F2 -isoprostane concentrations, was positively associated with percent body fat and truncal fat in youth. Oxidative stress levels were similar among African American and White American youth. Among markers of the metabolic syndrome, a significant difference between African American and White American youth was demonstrated only in the association of oxidative stress with diastolic blood pressure.

Female sex, small size at birth and low family income increase the likelihood of insulin resistance in late childhood: the Healthy Growth Study

OBJECTIVE

To identify among a wide range of perinatal indices, as well as certain family sociodemographic and parental characteristics, those independently associated with insulin resistance (IR) in late childhood.

METHODS

A representative sample of 2195 Greek schoolchildren, aged 9-13 yr, was examined, and based on the biochemical indices collected IR was estimated using the homeostasis model assessment (HOMA-IR < 3.16). Perinatal data were recorded from children's medical records, retrospectively, while family sociodemographics and parental anthropometrics were reported by parents.

RESULTS

The overall prevalence of IR was 28.4%, with a higher prevalence observed for girls compared with boys (p <0.05). Examination of univariate associations, per se, showed that maternal current and pre-pregnancy overweight/obesity, maternal smoking at early pregnancy, children's small birth weight, and rapid growth at infancy as well as female sex and non-Caucasian race increased the likelihood of IR. In contrast, folate supplementation during pregnancy, as well as higher paternal education and annual family income decreased the likelihood of IR in children. Inclusion of all above variables at a multivariable regression model highlighted female sex [odds ratios (OR): 1.67, 95% confidence intervals (CI): 1.30-2.13], small birth weight (OR: 1.41, 95% CI: 1.03-2.01), and higher annual family income (OR: 0.71, 95% CI: 0.53-0.95 for 12 000-30 000 € and OR: 0.68, 95% CI: 0.48-0.96 for >30 000 €) as the only significant correlates of IR after also controlling for children's body mass index (BMI) and Tanner stage.

CONCLUSIONS

The current study highlighted small birth weight and female sex as the only perinatal factors independently associated with the occurrence of IR in late childhood, when examined at a multivariable level with a wide range of perinatal indices as well as certain family sociodemographic and parental characteristics.

Glucose homeostasis and insulin resistance: prevalence, gender differences and predictors in adolescents

BACKGROUND

Adolescence, due to transient pubertal insulin resistance (IR), is associated with a higher risk for disturbances of glucose metabolism. The aim of our study was 1) to investigate the prevalence of disturbances of glucose metabolism, 2) to define gender specific homeostasis model assessment of insulin resistance (HOMA-IR) thresholds associated with increased cardiometabolic risks and 3) to provide predictors of HOMA-IR.

METHODS

The studied cohort consisted of Czech adolescents aged 13.0-17.9 years: 1,518 individuals of general population and three studied groups according weight category (615 normal weight, 230 overweight and 683 obese). The prevalence of IR, impaired fasting glucose (IFG) and type 2 diabetes was assessed. Risky HOMA-IR thresholds based on components of metabolic syndrome were investigated. HOMA-IR prediction was calculated taking into account age, blood pressure, multiple anthropometric, biochemical and hormonal parameters.

RESULTS

In general population cohort, the prevalence of IFG and type 2 diabetes was 7.0% and <0.5%, respectively. Boys regardless of weight presented significantly higher levels of blood glucose and higher prevalence of IFG than girls. Obese boys were found more insulin resistant than obese girls. HOMA-IR thresholds of 3.6 for girls and 4.4 for boys were associated with increased cardiometabolic risks. For both genders, the model of HOMA-IR prediction was composed of age, BMI, ratio of free triiodthyronine to free thyroxine, gamma-glutamyltransferase activity and levels of triglycerides and sex hormone-binding globulin.

CONCLUSIONS

The type 2 diabetes in adolescents, including those who were obese, was rarely diagnosed. Obese adolescent boys were at greater risk for IR and for IFG than obese girls. In adolescence, thresholds of HOMA-IR in contrast to predictors were found gender specific.

Chlorophytum borivilianum root extract maintains near normal blood glucose, insulin and lipid profile levels and prevents oxidative stress in the pancreas of streptozotocin-induced adult male diabetic rats

The effect of C. borivilianum root on blood glucose, glycated hemoglobin (HbAIc), insulin and lipid profile levels in diabetes mellitus are not fully understood. This study therefore investigated the effect of C. borivilianum root on the above parameters and oxidative stress of the pancreas in diabetes.

METHODS

C. borivilianum root aqueous extract (250 and 500 mg/kg/day) was administered to streptozotocin (STZ)-induced male diabetic rats for 28 days. Body weight, blood glucose, HbA1c, insulin, lipid profile levels and glucose homeostasis indices were determined. Histopathological changes and oxidative stress parameters i.e. lipid peroxidation (LPO) and antioxidant enzymes activity levels of the pancreas were investigated.

RESULTS

C. borivilianum root extract treatment to diabetic rats maintained near normal body weight, blood glucose, HbA1c, lipid profile and insulin levels with higher HOMA-β cell functioning index, number of Islets/pancreas, number of β-cells/Islets however with lower HOMA-insulin resistance (IR) index as compared to non-treated diabetic rats. Negative correlations between serum insulin and blood glucose, HbA1c, triglyceride (TG) and total cholesterol (TC) levels were observed. C. borivilianum root extract administration prevented the increase in lipid peroxidation and the decrease in activity levels of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) with mild histopathological changes in the pancreas of diabetic rats.

CONCLUSIONS

C. borivilianum root maintains near normal levels of these metabolites and prevented oxidative stress-induced damage to the pancreas in diabetes.

Dysmetabolic signals in "metabolically healthy" obesity

SUMMARY

BACKGROUND

Obesity is associated with decreased insulin sensitivity, atherogenic dyslipidemia and hypertension, but clinical studies have also identified a "metabolically healthy" obese phenotype.

OBJECTIVE

To compare the characteristics of so-called "metabolically healthy" obese (MHO), normal weight subjects (MHNW) and obese with insulin resistance in the United States National Health and Nutrition Examination Survey, 1999-2004 (NHANES).

DESIGN, SETTING AND PARTICIPANTS

Insulin resistance was defined by a homeostatic model assessment (HOMA) value in the upper tertile for the entire NHANES cohort. "Metabolic health" was defined as the absence of diabetes, insulin resistance, metabolic syndrome, and lipid-lowering therapy. The study evaluated the 314 MHO, 1173 MHNW and 843 insulin-resistant obese from among the 6485 non-diabetic, non-pregnant adults aged 20-79 years.

MAIN OUTCOME MEASURES

Demographic, metabolic, nutrition and physical activity features.

RESULTS

MHO and MHNW groups were similar regarding age, and fasting glucose and triglyceride levels. MHO had higher insulin (P < 0.0001), insulin resistance as measured with the homeostatic model (P < 0.0001), non-HDL cholesterol (P = 0.002 in females and P = 0.049 in males) and C-reactive protein levels (P < 0.0001 in females and P = 0.038 in males), and lower high-density lipoprotein cholesterol (HDL) levels (P < 0.002). In addition, MHO females had higher low-density lipoprotein (LDL) cholesterol levels (P = 0.012) and systolic blood pressure (P = 0.02), and lower intake of dietary fiber (P = 0.0009) and levels of physical activity (P = 0.002). Triglycerides levels were normal in the MHO group.

CONCLUSIONS

"Metabolically healthy" obese people have multiple dysmetabolic changes that may signal increased risk for coronary artery disease.

Insulin resistance determined by Homeostasis Model Assessment (HOMA) and associations with metabolic syndrome among Chinese children and teenagers

OBJECTIVE

The aim of this study is to assess the association between the degree of insulin resistance and the different components of the metabolic syndrome among Chinese children and adolescents. Moreover, to determine the cut-off values for homeostasis model assessment of insulin resistance (HOMA-IR) at MS risk.

METHODS

3203 Chinese children aged 6 to 18 years were recruited. Anthropometric and biochemical parameters were measured. Metabolic syndrome (MS) was identified by a modified Adult Treatment Panel III (ATP III) definition. HOMA-IR index was calculated and the normal reference ranges were defined from the healthy participants. Receiver operating characteristic (ROC) analysis was used to find the optimal cutoff of HOMA-IR for diagnosis of MS.

RESULTS

With the increase of insulin resistance (quintile of HOMA-IR value), the ORs of suffering MS or its related components were significantly increased. Participants in the highest quintile of HOMA-IR were about 60 times more likely to be classified with metabolic syndrome than those in the lowest quintile group. Similarly, the mean values of insulin and HOMA-IR increased with the number of MS components. The present HOMA-IR cutoff point corresponding to the 95th percentile of our healthy reference children was 3.0 for whole participants, 2.6 for children in prepubertal stage and 3.2 in pubertal period, respectively. The optimal point for diagnosis of MS was 2.3 in total participants, 1.7 in prepubertal children and 2.6 in pubertal adolescents, respectively, by ROC curve, which yielded high sensitivity and moderate specificity for a screening test. According to HOMA-IR > 3.0, the prevalence of insulin resistance in obese or MS children were 44.3% and 61.6% respectively.

CONCLUSIONS

Our data indicates insulin resistance is common among Chinese obese children and adolescents, and is strongly related to MS risk, therefore requiring consideration early in life. As a reliable measure of insulin resistance and assessment of MS risk, the optimal HOMA-IR cut-off points in this cohort were developed with variation regarding puberty. HOMA-IR may be useful for early evaluating insulin resistance in children and teenagers and could have a long-term benefit of preventive and diagnostic therapeutic intervention.

Relationship of epicardial adipose tissue thickness with early indicators of atherosclerosis and cardiac functional changes in obese adolescents with metabolic syndrome

OBJECTIVE

Epicardial adipose tissue thickness (EATT) is suggested as a new cardiometabolic risk factor. Carotid intima-media thickness (IMT) is a potential indicator of subclinical atherosclerosis in patients with metabolic syndrome (MS). We investigated the association of EATT with carotid IMT and cardiac functional changes in obese adolescents with MS.

METHODS

One hundred thirty-eight obese adolescents and 63 lean subjects were enrolled in the study. The obese subjects were divided into two subgroups based on the presence or absence of MS (MS group and non-MS group). All subjects underwent transthoracic echocardiographic examination for determination of left ventricular (LV) function, LV mass index (LVMI), and myocardial performance index (MPI). EATT and carotid IMT were also measured during echocardiography.

RESULTS

The average LVMI measurements were higher in both MS and non-MS obese patients in comparison with the lean children. The MS group had significantly higher LVMI measurements than the non-MS and lean groups (88.5±23.0, 67.5±24.8 g/m2, and 62.4±18.2 g/m2, respectively; p<0.01). Carotid IMT was higher in both the MS and non-MS obese patients in comparison with the lean group. The MS group had significantly higher carotid IMT measurements than the non-MS and lean groups (0.91±0.23, 0.78±0.18, and 0.52±0.08 mm, respectively; p<0.01). The EATT was also increased significantly in patients with MS compared to lean adolescents (7.42±1.55 vs. 4.28±0.79mm; p=0.001). EATT was positively correlated with body mass index-SDS, waist circumference, fasting glucose, insulin, homeostasis model assessment-insulin resistance, triglyceride levels, LV thickness, LVMI, and MPI in the MS obese group. EATT was the only independent predictor of carotid IMT in the multivariate analysis (β= 0.69, p<0.001).

CONCLUSION

The findings of the present study demonstrate a close relationship of EATT with carotid IMT and early cardiac dysfunction in obese adolescents with MS. Assessment of EATT and carotid IMT in routine echocardiographic examinations is suggested as a feasible and reliable method for the evaluation of obesity with MS and its related cardiovascular risks in children and adolescents.

The effect of obesity on the level of fractional exhaled nitric oxide in children with asthma

BACKGROUND

Several studies have demonstrated a relationship between asthma and obesity. However, the results have been conflicting with regard to the relationship between fractional exhaled nitric oxide (FeNO), used as a marker of airway inflammation in asthmatic patients, and obesity. We aimed to evaluate the association of FeNO with obesity and obesity-related metabolic complications in asthmatic and nonasthmatic children.

METHODS

The study population included children aged between 6 and 17 years and consisted of 4 groups: obese asthmatics (n = 52), normal-weight asthmatics (n = 49), obese nonasthmatics (n = 51) and normal-weight nonasthmatics (n = 42). FeNO measurement and spirometry were performed for all patients. To evaluate the metabolic complications, serum lipids, glucose and insulin levels were measured. Insulin resistance (IR) was estimated by the homeostasis model assessment, HOMA-IR. All participants were evaluated for the presence of metabolic syndrome (MS).

RESULTS

The mean age for the 194 subjects participating in the study was 11.6 ± 2.5 years. The FeNO level of asthma patients with MS was not different from those without MS (14.5 ± 8.0 and 16.7 ± 8.7, respectively, p = 0.449). In the nonasthmatic group, subjects with MS had a higher FeNO level than subjects without MS (12.5 ± 5.1 and 17.3 ± 8.3, respectively, p = 0.014). Spearman's rank correlation coefficients revealed a positive correlation between FeNO and body mass index (BMI; p = 0.049, r(2): 0.204) in the nonasthmatic group and after multivariate regression analysis, BMI still persisted as an independent risk factor for FeNO.

CONCLUSION

We found a positive correlation between BMI and FeNO level which suggests a link between obesity and increased airway inflammation in nonasthmatic children.

Fatty liver and insulin resistance in children with hypobetalipoproteinemia: the importance of aetiology

OBJECTIVE

Hepatic steatosis is strongly associated with insulin resistance, but causative mechanisms that link these conditions are still largely unknown. Nowadays, it is difficult to establish whether fatty liver is the cause of insulin resistance or instead the complex metabolic derangements of insulin resistance determine hepatic steatosis and its progression to fibrosis. In patients with familial hypobetalipoproteinemia (FHBL), hepatic steatosis is because of the genetically determined defective form of apolipoprotein B, independently of metabolic derangements. Therefore patients with FHBL represent a good in vivo model to evaluate the relationships between fatty liver and insulin sensitivity.

METHODS

We evaluated insulin resistance through HOMA-IR in 60 children with echografic and histological features of steatosis; 30 of whom had nonalcoholic fatty liver disease (NAFLD) and 30 had FHBL.

RESULTS

All patients had histological features of hepatic steatosis. Patients with FHBL were hypolipidemic, as expected. No significant differences between two groups were observed in liver function tests. IRI and HOMA-IR were statistically higher in NAFLD subjects compared to the FHBL group.

CONCLUSION

In our study, we demonstrated that in children with FHBL, hepatic steatosis is dissociated from insulin resistance. This finding suggests that fat accumulation per se may be not a sufficient causal factor leading to insulin resistance, and that other mediators may be involved in the development of alteration in glucose metabolism and metabolic syndrome in patients with NAFLD.

Oxidative stress is associated with the number of components of metabolic syndrome: LIPGENE study

Previous evidence supports the important role that oxidative stress (OxS) plays in metabolic syndrome (MetS)-related manifestations. We determined the relationship between the number of MetS components and the degree of OxS in MetS patients. In this comparative cross-sectional study from the LIPGENE cohort, a total of 91 MetS patients (43 men and 48 women; aged between 45 and 68 years) were divided into four groups based on the number of MetS components: subjects with 2, 3, 4 and 5 MetS components (n=20, 31, 28 and 12, respectively). We measured ischemic reactive hyperemia (IRH), plasma levels of soluble vascular cell adhesion molecule-1 (sVCAM-1), total nitrite, lipid peroxidation products (LPO), hydrogen peroxide (H₂O₂), superoxide dismutase (SOD) and glutathione peroxidase (GPx) plasma activities. sVCAM-1, H₂O₂ and LPO levels were lower in subjects with 2 or 3 MetS components than subjects with 4 or 5 MetS components. IRH and total nitrite levels were higher in subjects with 2 or 3 MetS components than subjects with 4 or 5 MetS components. SOD and GPx activities were lower in subjects with 2 MetS components than subjects with 4 or 5 MetS components. Waist circumference, weight, age, homeostatic model assessment-β, triglycerides (TGs), high-density lipoprotein and sVCAM-1 levels were significantly correlated with SOD activity. MetS subjects with more MetS components may have a higher OxS level. Furthermore, association between SOD activity and MetS components may indicate that this variable could be the most relevant OxS biomarker in patients suffering from MetS and could be used as a predictive tool to determine the degree of the underlying OxS in MetS.

Reevaluation of the prevalence of metabolic syndrome in an urban area of Turkey

OBJECTIVE

Our aim was to reveal a change in the prevalence of metabolic syndrome (MS) in the province of Konya in five years.

METHODS

We studied 202 obese children and adolescents (body mass index >95th percentile) aged between 7 and 18 years. The diagnosis of impaired glucose tolerance, type 2 diabetes mellitus (T2DM), and MS were defined according to the modified World Health Organization criteria adapted for children.

RESULTS

MS was found in 56.4 % with a significantly higher rate among adolescents aged 12-18 years (63.2%) than among prepubertal children aged 7-11 years (47%) (p=0.01). The prevalence figures for insulin resistance, glucose intolerance, and T2DM were 60, 8, and 2% among prepubertal children and 81.8, 12.8, and 0% among adolescents, respectively. The prevalence of fasting hyperinsulinemia in adolescents was significantly higher than in prepubertal children (p<0.001). Hypertension was significantly more common in adolescents (42.8%) than in prepubertal children (32.9%) (p=0.04).

CONCLUSIONS

We found that the incidence of MS in the city center of Konya approximately doubled in the last five years with increased rates of morbidity and abnormal lipid profiles.

Comparison of oral and intravenous glucose tolerance test derived sensitivity and secretory indices in obese adolescents

BACKGROUND

Insulin resistance increases type 2 diabetes risk in obese adolescents. Thus, quantitative tools measuring insulin sensitivity and secretion are important for risk assessment.

METHODS

Forty-four obese pubertal adolescents underwent oral glucose tolerance test (OGTT) and frequently sampled intravenous glucose tolerance test (FSIGT). We correlated OGTT-derived whole body sensitivity index (WBISI) with FSIGT-derived insulin sensitivity index (Si). Insulinogenic index (IGI) from OGTT was compared with acute insulin response to glucose (AIRg) from FSIGT.

RESULTS

Fasting insulin (r = -.64, P < .0005) and glucose (r = -.39 P ≤ .0005) predicted Si. The OGTT-derived index WBISI correlated with the FSIGT-derived Si (r = .608, P < .0005). IGI correlated with AIRg from FSIGT (r = .704, P < .0005).

CONCLUSIONS

OGTT-based measures correlated with FSIGT-derived measures of insulin sensitivity and secretion. In particular, we demonstrated that WBISI can be a reliable alternative to FSIGT-derived Si in clinical settings where OGTT is a more feasible option.

Obesity, metabolic syndrome, and insulin resistance in urban high school students of minority race/ethnicity

OBJECTIVES

To determine the point prevalences of metabolic syndrome (MetS) and its components among healthy weight, overweight, and obese inner-city public high school students, to compare the prevalences of MetS when using 2 different definitions (one with the impaired fasting glucose [IFG] level and the other with a homeostasis model assessment of insulin resistance [HOMA-IR] of 3.99 or higher to define the glucose regulation component), and to compare the degree to which HOMA-IR and fasting glucose level are associated with the other MetS components.

DESIGN

Cross-sectional analysis.

SETTING

Two New York City public high schools, from April 2008 through August 2011.

PARTICIPANTS

Convenience sample of 1185 high school youth, comprising predominantly Hispanic and African American students from low-income households, participating in The Banishing Obesity and Diabetes in Youth Project, a medical screening and education program.

MAIN OUTCOME MEASURES

Prevalences of the following individual MetS components: IFG threshold, HOMA-IR, hypertension, central adiposity, hypertriglyceridemia, and low high-density lipoprotein cholesterol. Rates of MetSIFG and MetSHOMA-IR were also assessed.

RESULTS

MetSIFG and MetSHOMA-IR point prevalences were both 0.3% in the healthy weight group; they were 2.6% and 5.9%, respectively, in the overweight group and were 22.9% and 35.1%, respectively, in the obese group (P < .05 for both). An IFG threshold of 100 mg/dL or higher was found in 1.0% of participants, whereas a HOMA-IR of 3.99 or higher was found in 19.5% of participants.

CONCLUSIONS

An elevated HOMA-IR is much more sensitive than an IFG threshold in identifying adolescents with metabolic dysregulation. Using a HOMA-IR threshold of 3.99 identifies more youth with MetS than using an IFG threshold of 100 mg/dL. In addition to increasing the sensitivity of MetS detection, HOMA-IR has a much higher association with the other MetS components than the IFG threshold and may better reflect a unified underlying pathologic process useful to identify youth at risk for disease.

Weight loss in obese prepubertal children: the influence of insulin resistance

BACKGROUND

Insulin resistance (IR), a link of paramount importance between obesity and cardiovascular/metabolic complications, seems to be implicated in weight changes.

OBJECTIVE

To determine whether IR could influence weight status during a 1-year intervention program in obese prepubertal children.

METHODS

Forty-four children with IR (IR group) and 42 children without IR (NIR group) were enrolled. Body mass index standard deviation score (BMI-SDS), waist circumference (WC), and homeostasis model assessment (HOMA-IR) were evaluated.

RESULTS

NIR children showed a significant reduction of BMI-SDS and WC at final assessment (p = 0.009 and p = 0.001, respectively), whereas IR children presented unchanged values. HOMA-IR decreased after intervention in the NIR group (p = 0.0008), but was exacerbated in IR children (p = 0.004). A positive and significant association between HOMA-IR at baseline and BMI at follow-up was found (B ± SE = 0.87 ± 0.24, p = 0.001). HOMA-IR at baseline was also significantly associated with WC at follow-up (B ± SE = 2.12 ± 0.69, p = 0.003).

CONCLUSIONS

IR seems to influence adiposity changes in obese prepubertal children. Further longitudinal studies are needed to verify the relationship between IR and weight loss during childhood.

School-based health center intervention improves body mass index in overweight and obese adolescents

Adolescents Committed to Improvement of Nutrition and Physical Activity (ACTION) was undertaken to determine feasibility of a school-based health center (SBHC) weight management program. Two urban New Mexico SBHCs were randomized to deliver ACTION or standard care. ACTION consisted of eight visits using motivational interviewing to improve eating and physical activity behavior. An educational nutrition and physical activity DVD for students and a clinician toolkit were created for use as menu of options. Standard care consisted of one visit with the SBHC provider who prescribed recommendations for healthy weight. Sixty nondiabetic overweight/obese adolescents were enrolled. Measures included BMI percentile, waist circumference, insulin resistance by homeostasis model assessment (HOMA-IR), blood pressure, triglycerides, and HDL-C levels. Pre- to postchanges for participants were compared between groups. Fifty-one students (mean age 15 years, 62% female, 75% Hispanic) completed pre- and postmeasures. ACTION students (n = 28) had improvements in BMI percentile (P = 0.04) and waist circumference (P = 0.04) as compared with students receiving standard care (n = 23). No differences were found between the two groups in blood pressure, HOMA-IR, triglycerides, and HDL-C. The ACTION SBHC weight management program was feasible and demonstrated improved outcomes in BMI percentile and waist circumference.

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 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.

[Ethnic influence on the prevalence of metabolic syndrome in an obese pediatric population]

INTRODUCTION

Obesity in children is becoming more prevalent. Obesity and type 2 diabetes is higher in the Latin American immigrant population.

OBJECTIVE

To analyze the influence of ethnicity on the prevalence of metabolic syndrome (MS) and its components in an obese pediatric population.

PATIENTS AND METHODS

A retrospective study of 616 obese children and adolescents (BMI ≥2 SD [Hernández 88-04]), was conducted on 142 Latin American children and 474 Caucasians, which compared the prevalence of metabolic syndrome and its components according to modified Cook criteria (2003): obesity+2 or more of the following components: HDL-cholesterol <40mg/dl, triglycerides >110mg/dl, systolic and/or diastolic blood pressure >p90 (Task Force 2004), and impaired glucose metabolism (ADA 2011). Hepatic function, family history of MS, HbA1c, insulin resistance (HOMA) and BMI evolution at one year of treatment with changes in lifestyle (diet and exercise) were also assessed.

RESULTS

Almost one-third (30.5%) of Latin American children had MS compared to 15.5% of Caucasians (OR=2.4 [CI 95%: 1.5-3.8]), P<.005] and OR=2.5 adjusting for sex, SD-BMI and puberty. Latin American children also had a higher insulin resistance (58.6% vs 42.8%, P<.005) and a worse outcome after one year of treatment.

CONCLUSION

There is a higher prevalence of MS in our Latin American obese pediatric population with poor adherence to the measures of change in lifestyle, making these patients a group with potentially increased risks of cardiovascular disease in adulthood.

Effect of body mass index-z score on adverse levels of cardiovascular disease risk factors

BACKGROUND

Cardiovascular disease (CVD) risk factors are associated with body mass index z-score (BMISD) and/or insulin resistance (IR). However, the correlation between adverse levels of these risk factors and BMISD, and the effect of IR on these associations are not fully understood in children. The aim of this study was to evaluate the association between adverse levels of CVD risk factors and BMISD, and the effect of IR on these associations in schoolchildren.

METHODS

Conventional CVD risk factors, C-reactive protein (CRP), uric acid (UA) and adiponectin were determined in 757 boys and 494 girls aged between 7 and 12 years. IR was assessed by the homeostasis model approximation index.

RESULTS

BMISD were linearly associated with relative risks having adverse levels of all factors, except for glucose and low-density lipoprotein cholesterol (LDL-C) in boys, and except for glucose, LDL-C and adiponectin in girls (P < 0.01-0.001). These associations were weakened after adjustment for IR, but still significant in cases of UA and CRP in boys and UA, high-density lipoprotein cholesterol and CRP in girls (P < 0.01-0.001).

CONCLUSION

The relative risk of having adverse levels of most CVD risk factors in school children increased across the entire range of BMISD. IR contributed to most of these relative risks, but BMISD itself also contributed to these relative risks. To prevent future development of CVD, it might be important for schoolchildren to maintain BMISD within normal range. However, in cases of hyper LDL-cholesterolemia, we should consider causes other than BMISD.

Distribution of the homeostasis model assessment of insulin resistance in Mexican children and adolescents

OBJECTIVE

Several cutoff points of the homeostasis model assessment of insulin resistance (HOMA-IR; varying from 2.5 to 4.0) have been suggested for diagnosing IR in youth. In this study, we determined the distribution of the HOMA-IR in Mexican children and adolescents.

DESIGN AND METHODS

A total of 6132 children and adolescents from San Luis Potosi, León, Queretaro, and Durango, which are cities in central and northern Mexico, were enrolled in a population-based cross-sectional study. Eligible participants were apparently healthy children and adolescents aged 6-18 years. Pregnancy and the presence of chronic illnesses were exclusion criteria.

RESULTS

A total of 3701 (60.3%) girls and 2431 (39.7%) boys were included in this study. In the overall population, the mean body mass index, insulin levels, and fasting glucose levels were 21.8±1.3 kg/m(2), 7.1±3.2 μU/ml, and 86.2±10.0 mg/dl respectively. The concentrations of insulin and fasting glucose gradually increased from 6 to 12 years of age, whereas the concentrations tended to plateau in the 13- to 18-year-old population. The absolute mean of the HOMA-IR was 2.89±0.7. The HOMA-IR gradually increased with age and reached a plateau at 13 years of age.

CONCLUSIONS

Because the insulin concentrations, glucose levels, and HOMA-IR exhibited a gradual increase with age that was not related to obesity, our results suggested that the evaluation of IR in children should be based on percentiles of the HOMA-IR rather than a dichotomous value derived from a single cutoff point.

Acanthosis nigricans as a clinical marker to detect insulin resistance in Caucasian children from West Virginia

The accuracy of acanthosis nigrcans (AN) as a dermatological clinical marker to predict insulin resistance (IR) has not been well established in children. A cohort of obese Caucasian children was prospectively recruited. Demographic data, body mass index values, and laboratory data were compared for the presence or absence of AN. A total of 76 children participated. In all, 46 (60.5%) children had AN, and 34 (44.7%) children were positive for IR (>3.16); 25 (32.9%) children were positive for both AN and IR. Sensitivity, specificity, positive and negative predictive values, and accuracy level for AN to detect IR in the obese children who participated in this study were 73.5%, 50%, 54.3%, 70%, and 49%, respectively. The correlation between insulin and fasting glucose levels in AN-negative or AN-positive patients was low (R (2) = 13% to 17%). Acanthosis nigricans was only a surrogate marker for IR. It is concluded that IR should be examined in every obese West Virginian child irrespective of his or her AN status.

Baseline insulin/glucose ratio as a marker for the clinical course of hyperglycemic critically ill children treated with insulin

OBJECTIVE

The objective of this study was to investigate the relations of baseline insulin/glucose ratio to the clinical course of critically ill children. Such information will provide insight into the pathophysiologic mechanisms leading to hyperglycemia and will optimize preventive and therapeutic measures for hyperglycemia in critically ill children.

METHODS

Sixty-four consecutively admitted critically ill children with hyperglycemia, defined as a blood glucose level higher than 8 mmol/L (>145 mg/dL) and treated with insulin according to a glucose-control protocol, were included. Demographic data and clinical and laboratory parameters were collected. Insulin sensitivity was investigated by calculating the ratio of insulin to the blood glucose level just before the start of insulin administration. Results are expressed as median (range).

RESULTS

Sixty-four children (24 girls) 7.0 y of age (0.3-16.9 y) with various diagnoses were included. A hyperinsulinemic response, indicated by an increased insulin/glucose ratio (>18 pmol/mmol), was seen in 55% of children. The durations of insulin therapy, mechanical ventilation, and pediatric intensive care unit length of stay in children with a hyperinsulinemic response were longer than in children with a hypoinsulinemic response.

CONCLUSION

Hyper- and hypoinsulinemic responses play a role in the occurrence of hyperglycemia in critically ill children. Each is associated with a particular clinical course after the initiation of insulin therapy. It would be worthwhile to further investigate if the insulinemic response to hyperglycemia, determined by the insulin/glucose ratio in combination with the type of organ dysfunction, could be used in clinical practice to determine the need for insulin therapy.

Poor oral hygiene and gingivitis are associated with obesity and overweight status in paediatric subjects

AIM

The association between obesity and periodontitis has been extensively investigated in adults but not in young people. Our aim is to evaluate whether overweight/obese paediatric patients have a greater chance of being affected by gingivitis than those of normal weight.

SUBJECTS AND METHODS

Ninety-eight subjects ranging between 10 and 17 years of age were classified as obese/overweight or normal weight on the basis of body mass index. Auxological data, blood pressure, insulin resistance, psychological profile, oral hygiene habits, plaque and gingival indices were collected.

RESULTS

Anthropometric measurements and blood pressure were significantly higher in overweight/obese subjects than in the normal-weight subjects (p<0001). The overweight/obese subjects showed a worse attitude towards oral hygiene. Two-way anova revealed a significant effect of obesity status (p<0001) on the gingival index. Logistic and linear regression analyses identified gingivitis as dependent on insulin resistance and bad oral hygiene rather than on the overweight/obese status simply defined. Negative psychological features related to physical and academic self-concept were also risk factors for gingivitis probably because they were related to a generic poor self-awareness.

CONCLUSION

The gingivitis observed in overweight and obese young subjects is probably due to a combination of metabolic and inflammatory profiles and neglected attitude towards oral hygiene.

Surrogate estimates of insulin sensitivity in obese youth along the spectrum of glucose tolerance from normal to prediabetes to diabetes

CONTEXT

In epidemiological studies of childhood obesity, simple and reliable surrogate estimates of insulin sensitivity are needed because the gold standard, the hyperinsulinemic-euglycemic clamp, is not feasible on a large scale.

OBJECTIVE

To examine the correlation of fasting and oral glucose tolerance test (OGTT)-derived surrogate indices of insulin sensitivity with the hyperinsulinemic-euglycemic clamp in obese adolescents with normal glucose tolerance, prediabetes, and diabetes.

PATIENTS AND DESIGN

A total of 188 overweight/obese adolescents (10 to <20 yr old) who completed a standard 2-h OGTT and 3-h hyperinsulinemic-euglycemic clamp were included. Fasting-derived surrogates [fasting glucose (G(F)), fasting insulin (I(F)), 1/I(F), G(F)/I(F), homeostasis model assessment and quantitative insulin sensitivity check index] and OGTT-derived surrogates [whole-body insulin sensitivity index and the ratio of glucose and insulin areas under the curve (Gluc(AUC)/Ins(AUC))] were calculated.

MAIN OUTCOME MEASURES

We evaluated the correlations between the clamp-measured insulin sensitivity and the surrogate estimates and area under the receiver operating characteristic curves.

RESULTS

Fasting indices (1/I(F), G(F)/I(F), homeostasis model assessment of insulin sensitivity, and quantitative insulin sensitivity check index) correlated significantly with clamp insulin sensitivity (r = 0.82, 0.78, 0.81, and 0.80, respectively), with lower correlations between the OGTT surrogates and clamp (whole-body insulin sensitivity index, r = 0.77; Gluc(AUC)/Ins(AUC), r = 0.62). The area under the receiver operating characteristic curves was more than or equal to 0.94 for all surrogates except Gluc(AUC)/Ins(AUC.) Across quartiles of clamp-measured insulin sensitivity, there was a significant overlap in individual values of I(F), 1/I(F), and G(F)/I(F).

CONCLUSION

In obese adolescents with normal or impaired glucose tolerance or diabetes, OGTT-derived surrogates do not offer any advantage over the simpler fasting indices, which correlate strongly with clamp insulin sensitivity. Surrogate indices of insulin sensitivity could be used in epidemiological studies but not to define insulin resistance in individual patients or research subjects.

High HOMA-IR, adjusted for puberty, relates to the metabolic syndrome in overweight and obese Chilean youths

OBJECTIVE

To determine how the homeostasis model assessment of insulin resistance (HOMA-IR) is related to metabolic risk in a sample of overweight and obese Chilean youths accounting for Tanner stage.

METHODS

A cross-sectional study assessing 486 overweight and obese youths (aged 5-15 years) recruited from the University of Chile, Pediatric Obesity Clinic. We measured anthropometry, Tanner stage, HOMA-IR, and laboratory tests related to metabolic risk. HOMA-IR was categorized by quartile for children (Tanner stages I and II) and adolescents (Tanner stage III and above) from a normative Chilean sample.

RESULTS

Children and adolescents with HOMA-IR in the highest quartile were likely to have higher body mass index (BMI) Z-scores, elevated waist circumference, systolic and diastolic blood pressure, and triglycerides and low high-density lipoprotein. HOMA-IR had good negative predictive value for characteristics of the metabolic syndrome (MetS; 0.82). In a multivariate regression model, BMI Z-score [odds ratio (OR) 1.5] and HOMA-IR (OR 3.3) predicted 22% of the variance for the MetS, with 36% of the explained variance attributed to HOMA-IR.

CONCLUSIONS

In a large clinical sample of overweight and obese Chilean youths, HOMA-IR ≥ 75th percentile was significantly associated with the cluster of factors referred to as the MetS. We emphasize the importance of establishing percentiles for HOMA-IR based on a normative sample and taking Tanner stage into account. Although BMI is easy to assess and interpret with minimal costs in a clinical setting, adding HOMA-IR explains more of the variance in the MetS than BMI Z-score alone.

Coping skills training in a telephone health coaching program for youth at risk for type 2 diabetes

INTRODUCTION

The purpose of this article is to describe components of a health coaching intervention based on coping skills training delivered via telephone. This intervention was provided to urban adolescents at risk for type 2 diabetes mellitus (T2DM), reinforcing a school-based curriculum designed to promote a healthy lifestyle and prevent T2DM.

METHOD

Health coaching via telephone was provided to at-risk urban youth enrolled in a study of an intervention to reduce risk for T2DM. Vignettes are used to describe the use of several coping skills in this high-risk youth population.

RESULTS

A variety of vignettes illustrate how telephone health coaching reinforced lifestyle changes in students by incorporating coping skills training.

DISCUSSION

Given the benefits and the challenges of the telephone health coaching intervention, several suggestions for others who plan to use a similar method are described.

Serum osteocalcin level is positively associated with insulin sensitivity and secretion in patients with type 2 diabetes

OBJECTIVE

Bone is being recognized as an endocrine organ. Although previous animal studies showed that osteocalcin stimulated the expression of insulin in islets and of adiponectin in adipocytes with increased insulin secretion and sensitivity, the associations of serum osteocalcin with those parameters remain unclear in humans.

METHODS

In this cross-sectional study, we employed 101 postmenopausal women and 152 men with type 2 diabetes, who have not taken drugs for diabetes or osteoporosis. We also examined 75 g oral glucose tolerance test (OGTT) in 18 postmenopausal women and 20 men who visited our clinic for medical check-up for diabetes.

RESULTS

In both postmenopausal women and men, multiple regression analysis adjusted for age, body mass index, and serum creatinine showed that serum osteocalcin level was significantly and negatively associated with fasting plasma glucose, HbA(1c), %Trunk fat, and homeostasis model assessment (HOMA) for insulin resistance (p<0.05), and positively with HOMA for beta-cell function (p<0.05). In addition, significant positive association of serum osteocalcin level with serum adiponectin level was found in postmenopausal women (p<0.05), but not in men. In the OGTT examinations, subjects were divided into tertiles by their serum osteocalcin levels in each gender. Postmenopausal women in the lowest tertile showed hyperglycemia and hyperinsulinemia compared to those in the highest tertile after oral glucose loading (p<0.05). Men in the lowest tertile also exhibited hyperinsulinemia (p<0.05), while hyperglycemia was not found.

CONCLUSION

These findings indicate that serum osteocalcin level is positively associated with insulin sensitivity and secretion in Japanese patients with type 2 diabetes.

Galactose promotes fat mobilization in obese lactating and nonlactating women

BACKGROUND

Galactose consumption as the only carbohydrate source results in little increase in plasma glucose and insulin concentrations when compared with fasting. Lower insulin might promote endogenous lipolysis during meal absorption, which may facilitate fat loss.

OBJECTIVE

The objective was to test the hypothesis that consumption of an isocaloric, isonitrogenous galactose drink will result in higher rates of lipolysis and fat oxidation than consumption of a glucose drink in obese lactating and nonlactating women.

DESIGN

Seven healthy, obese, exclusively breastfeeding women and 7 healthy, obese, nonlactating women were studied on 2 occasions according to a randomized, crossover, single-blinded design. Subjects received drinks providing ≈70% of the daily estimated energy requirement, of which 60% was either glucose or galactose. The primary outcomes were the rate of appearance (Ra) of glycerol and palmitate, and the secondary outcomes were glucose Ra, milk production, energy expenditure, and substrate oxidation.

RESULTS

Plasma glucose and insulin concentrations were lower (P < 0.05) and those of glycerol, palmitate, free fatty acids, and triglycerides were higher (P < 0.05) during galactose than during glucose feeding in both nonlactating and lactating women. During galactose feeding, glucose Ra was lower (P < 0.01) and glycerol, palmitate, and free fatty acid Ra were higher (P < 0.01) in both groups. During galactose feeding in all women combined, fat oxidation was higher (P = 0.01) and protein oxidation was lower (P < 0.01). Milk production, energy expenditure, and carbohydrate oxidation were similar between glucose and galactose feeding.

CONCLUSIONS

Galactose consumption is associated with higher endogenous fat mobilization and oxidation during meal absorption. Long-term studies are required to determine whether galactose as an exclusive carbohydrate source would promote body fat loss in obese subjects.

Effects of short-term chromium supplementation on insulin sensitivity and body composition in overweight children: randomized, double-blind, placebo-controlled study

Excessive body weight is inversely associated with insulin sensitivity in children and adults. Chromium supplementation produces modest improvement in insulin sensitivity in adults. The aim of this study was to examine the beneficial effects of chromium supplementation on insulin sensitivity and body composition in overweight children simultaneously modifying lifestyle. Twenty-five overweight children aged 9-12 years were randomized to receive either 400 μg of chromium chloride or placebo in double-blind fashion, during a 6-week lifestyle modification regimen that included nutritional education and 3×90 min of aerobic physical activity weekly. Insulin sensitivity was demonstrated using homeostasis model assessment-insulin resistance and quantitative insulin sensitivity check index (QUICKI). Changes in body mass index (BMI; kg/m(2)), BMI Z-score, waist circumference, body composition and fasting plasma glucose were measured. Although no significant benefit of chromium supplementation over placebo was evident for BMI, BMI Z-score and fasting insulin level, children who received chromium chloride demonstrated more positive changes versus the placebo group in HOMA (-1.84±1.07 vs. 0.05±0.42, P=.05), QUICKI (0.02±0.01 vs. -0.002±0.01, P=.05), lean body mass (2.43±0.68 kg vs. 1.36±1.61 kg, P=.02) and percentage body fat (-3.32±1.29% vs. 0.65±1.05%, P=.04). The desirable effects of chromium supplementation on insulin sensitivity and body composition were more apparent in pre-pubertal children. These results suggest that short-term chromium supplementation can improve insulin sensitivity and body composition in overweight children.

Disturbance of glucose homeostasis after pediatric cardiac surgery

This study aimed to evaluate the time course of perioperative blood glucose levels of children undergoing cardiac surgery for congenital heart disease in relation to endogenous stress hormones, inflammatory mediators, and exogenous factors such as caloric intake and glucocorticoid use. The study prospectively included 49 children undergoing cardiac surgery. Blood glucose levels, hormonal alterations, and inflammatory responses were investigated before and at the end of surgery, then 12 and 24 h afterward. In general, blood glucose levels were highest at the end of surgery. Hyperglycemia, defined as a glucose level higher than 8.3 mmol/l (>150 mg/dl) was present in 52% of the children at the end of surgery. Spontaneous normalization of blood glucose occurred in 94% of the children within 24 h. During surgery, glucocorticoids were administered to 65% of the children, and this was the main factor associated with hyperglycemia at the end of surgery (determined by univariate analysis of variance). Hyperglycemia disappeared spontaneously without insulin therapy after 12-24 h for the majority of the children. Postoperative morbidity was low in the study group, so the presumed positive effects of glucocorticoids seemed to outweigh the adverse effects of iatrogenic hyperglycemia.

Vitamin d deficiency in obese children and its relationship to insulin resistance and adipokines

Low-serum concentrations of 25-hydroxyvitamin D [25(OH)D] are associated with insulin resistance in adults. Less data are available in pediatric populations. Serum 25(OH)D serum concentrations were assessed in 125 obese and 31 nonobese children (age 11.9 ± 2.7 y, range 6-16 y, 49% male) living in Bonn, Germany. The relationship between 25(OH)D, measured by liquid chromatography-tandem mass spectrometry, and measures of insulin sensitivity and adipokines adiponectin and resistin were analyzed. Seventy-six % of subjects were 25(OH)D deficient (<20 ng/mL). Higher insulin, homeostasis model assessment-insulin resistance (HOMA-IR r = -0.269, P = 0.023), and hemoglobin A1c (HbA(1c)) as well as lower quantitative insulin-sensitivity check index (QUICKI r = 0.264, P = 0.030) values were found in obese children with lower 25(OH)D concentrations even after adjustment for gender, age, and body mass index. Furthermore, 25(OH)D correlated significantly with adiponectin, but not with resistin. Our results suggest that hypovitaminosis D is a risk factor for developing insulin resistance independent of adiposity.

HOMA-IR and QUICKI: decide on a general standard instead of making further comparisons

AIM

To limit further comparisons between the two fasting indices Homeostasis Model Assessment for Insulin Resistance (HOMA-IR) and Quantitative Insulin Sensitivity Check Index (QUICKI), and to examine their robustness in assessing insulin sensitivity.

METHODS

A total of 191 obese children and adolescents (age 13.9 ± 2.9 years, BMI SDS 6.1 ± 1.6), who had undergone a Frequently Sampled Intravenous Glucose Tolerance Test (FSIVGTT), were included. Receiver operating characteristic curve (ROC) analysis was used to compare indices in detecting insulin resistance and Bland-Altman plots to investigate agreement between three consecutive fasting samples when compared to using single samples.

RESULTS

ROC analysis showed that the diagnostic accuracy was identical for QUICKI and HOMA-IR [area under the curve (AUC) boys 0.80, 95%CI 0.70-0.89; girls 0.80, 0.71-0.88], while insulin had a nonsignificantly lower AUC (boys 0.76, 0.66-0.87; girls 0.75, 0.66-0.84). Glucose did not perform better than chance as a diagnostic test (boys 0.47, 0.34-0.60; girls 0.57, 0.46-0.68). Indices varied with consecutive sampling, mainly attributable to fasting insulin variations (mean maximum difference in HOMA-IR -0.8; -0.9 to -0.7).

CONCLUSIONS

Using both HOMA-IR and QUICKI in further studies is superfluous as these indices function equally well as predictors of the FSIVGTT sensitivity index. Focus should be on establishing a general standard for research and clinical purposes.

Polycystic ovary syndrome in adolescence

The definition of polycystic ovary syndrome in very young girls is complicated by the fact that many features typical of the syndrome can also be seen as physiological stages in the maturation of the hypothalamus-pituitary-ovarian axis. The role of reduced insulin sensitivity in the pathogenesis and evolution of the disorder has gained more importance over recent years: both elevated androgen levels and being overweight may influence the impairment of glucose metabolism. Our study focused on 250 girls in the first 8 years of gynecological age. We analyzed the prevalence of different phenotypes according to the Rotterdam criteria and the impact of higher BMI on androgen levels and on fasting screening markers of glucose metabolism. In a smaller sample, we performed a more detailed evaluation of the glucose metabolism parameters; our findings indicated that in this age group, being overweight plays a major role in the deterioration of the clinical picture.

Feasibility of intravenous glucose tolerance testing prior to puberty

OBJECTIVES

1) Report the feasibility of completing the 180-minute Frequently Sampled Intravenous Glucose Tolerance Test (FSIVGTT) in healthy weight, overweight and obese pre-pubertal children and, 2) describe the finalized FSIVGTT protocol after addendums were implemented to decrease the frequency of mild adverse events and improve test completion rates.

METHODS

Insulin sensitivity was determined by FSIVGTT.

RESULTS

FSIVGTT was attempted in a total of 22 study participants. Insulin sensitivity was successfully assessed in 15 study participants (8 males, 7 females, 10 Caucasian, 4 African American, 1 Pacific Islander, age range 7-9 years). Mean insulin sensitivity was 15.1+/-9.8 (mmicro/l)(-1) min(-1) range 4.4-43.2 (mmicro/l)(-1) min(-1). However, seven study participants experienced mild adverse events of hypoglycemia. Several addendums were made to the FSIVGTT protocol to ensure study participants' comfort and safety, and to decrease the frequency of mild adverse events and increase test completion rates.

CONCLUSIONS

Addendums made to FSIVGTT protocol allowed successful completion of FSIVGTT in 15 (68%) of the 22 children. These results demonstrate that FSIVGTT is challenging, yet feasible in healthy lean and obese pre-pubertal children.

Subclinical metabolic abnormalities associated with obesity in prepubertal Mexican schoolchildren

Childhood obesity has increased to epidemic levels and is considered a public health problem due to its association with a number of metabolic abnormalities, which are being detected at earlier stages of life. The objective was to evaluate the association between the presence of subclinical metabolic abnormalities (SMA) and obesity in a sample of pre-pubertal Mexican schoolchildren. Children of both sexes and 6 to 13 years old were questioned for signs of puberty, underwent anthropometric measurement and had their Body Mass Index (BMI) calculated. Two groups were formed: those with obesity (case group) and those with normal weight paired by age and chosen randomly (control group). Fasting insulin, glucose and cholesterol were measured. 92 children were included, 46 in each group, mean age 9.9 and 9.5 years old, respectively (p = 0.97). A higher frequency of hyperinsulinism was found in the case group: Fasting insulin > 15 mU/ml, 75% vs. 21% (case group vs. control group, respectively); fasting glucose to insulin ratio < 6, 72% vs. 24%; HOMA IR > 2.7, 83% vs. 14%; and decrease in QUICKI (< 0.3), 80% vs. 19% (p = 0.000). Hypercholesterolemia was 25% vs. 15% (p = 0.22), impaired fasting glucose 28% vs. 8% (p = 0.01), and family history of diabetes mellitus (DM) 35% vs. 9% (OR = 5.6; 95% CI = 1.5-22.2; p = 0.002). In this sample of Mexican schoolchildren, obesity was associated to a higher frequency of SMA, such as hyperinsulinism and impaired fasting glucose, and to a family history of DM.

Sleep-disordered breathing is increased in obese adolescents with craniopharyngioma compared with obese controls

CONTEXT

Retrospective studies suggest that adolescents with craniopharyngioma and hypothalamic obesity have increased sleep-disordered breathing (SDB).

OBJECTIVES

The objectives of this study were to compare the prevalence of SDB in adolescents with craniopharyngioma-related obesity compared with body mass index (BMI)-matched controls and to explore possible relationships between SDB, insulin resistance, and adipocytokines.

DESIGN

This was a cross-sectional study of obese craniopharyngioma and obese control adolescents.

SETTING

Subjects were evaluated in the clinical investigation unit at the Hospital for Sick Children, Toronto.

PATIENTS

Fifteen patients with craniopharyngioma-related obesity and 15 BMI-matched controls were recruited and tested.

INTERVENTIONS

Each subject underwent fasting blood work, frequent sampled iv glucose tolerance test, polysomnography, and abdominal magnetic resonance imaging with calculation of visceral and sc adipose tissue.

MAIN OUTCOME MEASURES

Main measures included insulin sensitivity, sleep efficiency, and fragmentation.

RESULTS

Insulin sensitivity was lower in craniopharyngioma subjects compared with control subjects (0.96 +/- 0.34 vs. 1.67 +/- 0.7, P = 0.01). Sleep-onset latency (19.3 +/- 27.8 vs. 31.9 +/- 23.4, P = 0.03) and oxygen saturations (rapid eye movement sleep: 89.0 +/- 5.1 vs. 94.2 +/- 2.3, P < 0.001; non-rapid eye movement sleep: 88.4 +/- 5.6 vs. 94.3 +/- 1.5, P < 0.001) were lower in craniopharyngioma. Obstructive apnea-hypopnea index (OAHI) (7.5 +/- 9.0 vs. 1.5 +/- 1.5, P = 0.03) was higher in craniopharyngioma. Respiratory distress index and OAHI correlated negatively with adiponectin concentrations (r = -0.61, P = 0.03, r = -0.71, P = 0.006, respectively) in craniopharyngioma. On multiple regression, TNF-alpha and craniopharyngioma were independent positive predictors of sleep-onset latency and adiponectin and craniopharyngioma were significant predictors (negative and positive, respectively) of OAHI.

CONCLUSIONS

SDB is increased in adolescents with craniopharyngioma-related obesity compared with BMI-matched controls. Routine polysomnography should be considered in obese patients with craniopharyngioma and appropriate treatment initiated.

Childhood hypo-adiponectinaemia but not hyper-leptinaemia is associated with insulin insensitivity 6 years later

BACKGROUND

Biomarkers of metabolism and inflammation may predict children with increased diabetes risk.

OBJECTIVE

To study plasma adiponectin, leptin, IL-8, and hepatocyte growth factor (HGF) in childhood and their independent associations with insulin insensitivity, cross-sectional and in 6-yr prospective.

SUBJECTS

Danish 8- to 10-yr-olds and 14- to 16-yr-olds from the European Youth Heart Studies I and II.

METHODS

Cross-sectional (n = 386) and prospective (n = 246) linear regressions of baseline concentrations of plasma biomarkers and insulin insensitivity at baseline and 6 yr later. Adjustments were made at four progressive steps for sex, sexual maturity, body mass index (BMI), other biomarkers, physical activity, and school location as well as baseline insulin insensitivity in prospective analyses. Insulin insensitivity was measured using homeostasis model assessment standardized to the sample mean [homoestasis model assessment (HOMA) Z-scores]. Plasma biomarkers were quantified using solid-phase protein immunoassays. Overweight was defined as the highest BMI tertile.

RESULTS

Among overweight but not lean children at baseline, one SD difference in baseline plasma adiponectin was associated with -0.41 SD difference in HOMA Z-scores 6 yr later (p = 0.006). At baseline, one SD difference in plasma leptin was associated with 0.36 SD difference in HOMA Z-scores (p =< 0.0001) among 8- to 10-yr-olds, but a prospective association was not found.

CONCLUSIONS

We found a direct relationship between childhood hypo-adiponectinaemia and insulin insensitivity in adolescence. This association was stronger for overweight than for normal weight children. Hyper-leptinaemia was associated with concurrent insulin insensitivity at baseline but not 6 yr later.

Asthma and insulin resistance in children

BACKGROUND AND OBJECTIVE

Increased BMI is a risk factor for asthma in children and may be related to adipokines. Adipokines affect insulin-stimulated glucose uptake in vitro but, to date there is little evidence for such a role in vivo. We explored relationships between obesity and allergic asthma in children.

METHODS

Twenty-one allergic asthmatics (AA) and 10 non-allergic healthy controls, aged 6-17.9 years were studied. AA group included children with a positive mannitol challenge test, >25 ppb of exhaled nitric oxide and a positive skin prick test. BMI z-scores were calculated. Blood levels of insulin, glucose, leptin, resistin, tumour necrosis factor-alpha, IL-4, IL-5 and IL-6 were measured. Insulin resistance (IR) was estimated using the homeostasis model assessment (HOMA).

RESULTS

There was no significant difference in BMI z-scores between AA and healthy controls (mean: 0.01 vs -0.10). However, significant differences were found in the blood levels of IL-6 (P = 0.05), IL-4 (P = 0.04), IL-5 (P = 0.01) and leptin (P = 0.02). IR was only found in the AA group (42.85%). Homeostasis model assessment insulin resistance (HOMA-IR) was significantly related to IL-6 (r = 0.44, P = 0.05) and tumour necrosis factor-alpha (r = -0.45, P = 0.05).

CONCLUSIONS

IR was observed in AA. Our findings are suggestive of a complex interaction between the inflammatory state and adiposity, allergy and asthma.

Evaluation of glycaemic status in young people with clinical insulin resistance; fasting glucose, fasting insulin or an oral glucose tolerance test?

OBJECTIVE

It is important to identify young people with prediabetes for early intervention. However, it is unclear how to best screen overweight and obese young people for prediabetes. The objective of this study was to compare fasting indices with an oral glucose tolerance test (OGTT) in diagnosing prediabetes.

DESIGN

Retrospective review.

PATIENTS

A total of 224 young people, aged 12.0 years (range: 3.2-17.3 years), with clinical features of insulin resistance, who had an OGTT between 2000 and 2007 at a tertiary children's hospital, Sydney, Australia.

MEASUREMENTS

Oral glucose tolerance test.

RESULTS

A total of 168 (75%) participants had normal glucose tolerance, 45 (20%) had prediabetes and 11 (5%) had type 2 diabetes; 29 of those with prediabetes and 10 with type 2 diabetes were identified by fasting glucose criteria alone. Young people with normal fasting glucose and fasting insulin < or =180 pmol/l had lower insulin resistance (homeostasis model assessment median 1.9 vs. 4.2, P < 0.001), higher insulin sensitivity index (2.4 vs. 1.0, P < 0.001) and a lower early insulin response (insulinogenic index 2.5 vs. 4.1, P < 0.001) compared to those with normal fasting glucose and higher fasting insulin levels. If a fasting insulin cut point (< or =180 pmol/l) was used in addition to fasting glucose to determine the need for an OGTT, 114 (68%) young people with normal glucose tolerance would have avoided the test. By contrast, the diagnosis of impaired glucose tolerance, identified by an OGTT, would have been missed in three children.

CONCLUSION

Fasting glucose and insulin levels should be measured in young people with insulin resistance before undertaking a time- and resource-intensive OGTT.

The effect of low-carbohydrate diet on left ventricular diastolic function in obese children

BACKGROUND

This study was conducted to evaluate left ventricle (LV) functions using conventional and tissue Doppler imaging in childhood obesity and to identify the effects of diet on LV diastolic functions.

METHODS

Conventional and tissue Doppler echocardiographic measurements were compared in 34 obese children and 24 age- and gender-matched lean controls. Fasting plasma glucose, insulin and homeostatic model assessment of insulin resistance levels were also obtained. Thirty-one of the obese children were subjected to a low-carbohydrate diet and their follow-up measurements were obtained after 6 months.

RESULTS

Left atrial diameter, LV mass and LV mass index were higher in obese children than in lean controls. Lateral mitral myocardial early diastolic (E(m)) and peak E(m)/myocardial late diastolic (A(m)) were lower, and mitral E/E(m) and lateral mitral myocardial isovolumetric relaxation time were higher in obese subjects than in lean controls. Insulin and homeostatic model assessment of insulin resistance levels were higher in obese patients and decreased significantly after diet. After diet therapy, lateral mitral E(m) and peak E(m)/A(m), were increased, mitral E/E(m) and myocardial isovolumetric relaxation time were decreased.

CONCLUSIONS

Obesity predisposes children to increased preload reserve, left ventricular subclinical diastolic dysfunction and deterioration in diastolic filling. Weight reduction with a low-carbohydrate diet seems to be associated with significant improvement in LV diastolic function and a decrease in diastolic filling, as well as causing reversal in insulin resistance seen in obese children.

Insulin sensitivity and secretion in children and adolescents with hypothalamic obesity following treatment for craniopharyngioma

BACKGROUND

Craniopharyngioma (CP), a tumour occurring in the hypothalamic-pituitary area, results in morbid obesity in 25-60% of affected children. It has been suggested that abnormalities of insulin secretion and/or insulin action due to hypothalamic injury may be associated with weight gain and the metabolic syndrome in this population.

AIM

To evaluate: (i) insulin secretion (IS) and insulin sensitivity (Si); (ii) features of the metabolic syndrome (MS) and (iii) factors involved in risk for diabetes and heart disease in obese youth treated for CP.

METHODS

Obese subjects treated for CP were compared to BMI-matched control subjects. All subjects underwent anthropometric, blood pressure, resting energy expenditure and body fat assessment. Cholesterol and inflammatory markers, oral glucose tolerance test (OGTT) and frequent sampling intravenous glucose tolerance test (FSIGT), with calculation of IS and Si, were performed.

RESULTS

Fifteen CP subjects and 15 controls (C) were studied. There were no differences between CP and C for age, gender, BMI or pubertal status. MS was present in 10/15 CP and 3/15 C (P = 0.03), including impaired glucose tolerance (IGT) in 6/15 CP and 0/15 C (P = 0.02). Measures of IS, including first and second phase IS, and insulin area-under-the-curve (AUC(ins)) during OGTT, were significantly higher in CP. Si, measured by frequent sampled intravenous glucose tolerance test (Si-FSIGT), was significantly lower in CP subjects (0.96 +/- 0.34 vs. 1.67 +/- 0.7; P = 0.01). AUC(ins) was negatively correlated with Si-FSIGT (r = -0.62; P = 0.003).

CONCLUSION

Children with CP and hypothalamic obesity have more features of MS, increased IS and IGT prevalence and lower Si compared with BMI-matched controls.