Insulin resistance: link to the components of the metabolic syndrome and biomarkers of endothelial dysfunction in youth

Insulin-resistance in paediatric age: Its magnitude and implications

Insulin resistance (IR) is insulin failure in normal plasma levels to adequately stimulate glucose uptake by the peripheral tissues. IR is becoming more common in children and adolescents than before. There is a strong association between obesity in children and adolescents, IR, and the metabolic syndrome components. IR shows marked variation among different races, crucial to understanding the possible cardiovascular risk, specifically in high-risk races or ethnic groups. Genetic causes of IR include insulin receptor mutations, mutations that stimulate autoantibody production against insulin receptors, or mutations that induce the formation of abnormal glucose transporter 4 molecules or plasma cell membrane glycoprotein-1 molecules; all induce abnormal energy pathways and end with the development of IR. The parallel increase of IR syndrome with the dramatic increase in the rate of obesity among children in the last few decades indicates the importance of environmental factors in increasing the rate of IR. Most patients with IR do not develop diabetes mellitus (DM) type-II. However, IR is a crucial risk factor to develop DM type-II in children. Diagnostic standards for IR in children are not yet established due to various causes. Direct measures of insulin sensitivity include the hyperinsulinemia euglycemic glucose clamp and the insulin-suppression test. Minimal model analysis of frequently sampled intravenous glucose tolerance test and oral glucose tolerance test provide an indirect estimate of metabolic insulin sensitivity/resistance. The main aim of the treatment of IR in children is to prevent the progression of compensated IR to decompensated IR, enhance insulin sensitivity, and treat possible complications. There are three main lines for treatment: Lifestyle and behavior modification, pharmacotherapy, and surgery. This review will discuss the magnitude, implications, diagnosis, and treatment of IR in children.

Metabolic Syndrome and Its Components are Linked with Increased Risk of Non-Melanoma Skin Cancers in Iranian Subjects: A Case-Control Study

The associations between components of metabolic syndrome (MetS), insulin resistance (IR), and several malignancies have been reported. However, the possible link between IR and dermal malignancies, including non-melanoma skin cancers (NMSCs), has not been investigated to date. In this study, we aimed to examine the possible association between components of MetS, IR, adhesion molecules, and NMSC for the first time. This was a case-control study comprising 73 confirmed cases of NMSC and 72 unrelated healthy controls. Anthropometric and biochemical assessments including fasting blood lipid profile, glucose and insulin assays were performed. To evaluate IR, HOMA-IR formula was used. Though fasting serum glucose showed no significant between-group difference, serum concentrations of insulin (p = 0.048) as well as HOMA-IR (p = 0.037) were both significantly higher in NMSC group than in controls. Logistic regression analysis revealed significant associations between waist circumference (OR: 1.04, 95% CI: 1.007-1.080, p = 0.018), percent of visceral fat (OR: 1.10, 95% CI: 1.024-1.190, p = 0.01), HOMA-IR (OR: 1.169, 95% CI: 1.004-1.360, p = 0.044), circulating VCAM-1 concentrations (OR: 1.005, 95% CI: 1.003-1.007, p < 0.001) and NMSC risk. Interestingly, the occurrence of MetS was significantly higher in subjects with NMSC than in healthy controls (p = 0.038). MetS and its components were associated with increased NMSC risk.

Insulin sensitivity variations in apparently healthy Arab male subjects: correlation with insulin and C peptide

INTRODUCTION

Decreased insulin sensitivity occurs early in type 2 diabetes (T2D). T2D is highly prevalent in the Middle East and North Africa regions. This study assessed the variations in insulin sensitivity in normal apparently healthy subjects and the levels of adiponectin, adipsin and inflammatory markers.

RESEARCH DESIGN AND METHODS

A total of 60 participants (aged 18-45, body mass index <28) with a normal oral glucose tolerance test (OGTT) completed hyperinsulinemic-euglycemic clamp (40 mU/m²/min) and body composition test by dual-energy X-ray absorptiometry scan. Blood samples were assayed for glucose, insulin, C peptide, inflammatory markers, oxidative stress markers, adiponectin and adipsin.

RESULTS

The subjects showed wide variations in the whole-body glucose disposal rate (M value) from 2 to 20 mg/kg/min and were divided into three groups: most responsive (M>12 mg/kg/min, n=17), least responsive (M≤6 mg/kg/min, n=14) and intermediate responsive (M=6.1-12 mg/kg/min, n=29). Insulin and C peptide responses to OGTT were highest among the least insulin sensitive group. Triglycerides, cholesterol, alanine transaminase (ALT) and albumin levels were higher in the least responsive group compared with the other groups. Among the inflammatory markers, C reactive protein (CRP) was highest in the least sensitivity group compared with the other groups; however, there were no differences in the level of soluble receptor for advanced glycation end products and Tumor Necrosis Factor Receptor Superfamily 1B (TNFRS1B). Plasma levels of insulin sensitivity markers, adiponectin and adipsin, and oxidative stress markers, oxidized low-density lipoprotein, total antioxidant capacity and glutathione peroxidase 1, were similar between the groups.

CONCLUSIONS

A wide range in insulin sensitivity and significant differences in triglycerides, cholesterol, ALT and CRP concentrations were observed despite the fact that the study subjects were homogenous in terms of age, gender and ethnic background, and all had normal screening comprehensive chemistry and normal glucose response to OGTT. The striking differences in insulin sensitivity reflect differences in genetic predisposition and/or environmental exposure. The low insulin sensitivity status associated with increased insulin level may represent an early stage of metabolic abnormality.

Oral glucose tolerance response curve predicts disposition index but not other cardiometabolic risk factors in healthy adolescents

OBJECTIVES

In obese adults the shape of the glucose response curve during an oral glucose tolerance test (OGTT) predicts future type 2 diabetes. Patients with an incessant increase or monophasic curves have increased risk compared to those with biphasic curves. Since type 2 diabetes is associated with increased cardiometabolic risk, we studied whether differences in OGTT response curve are associated with differences in cardiometabolic risk factors in healthy adolescents across a wide body mass index (BMI) range.

METHODS

Sixty-nine (33F/36M), white adolescents (age: 15.2 ± 1.7 years; BMI: 21.5 ± 4.7 kg/m²; mean ± SD) were studied. Risk factors measured included percent body fat, blood pressure, lipids, augmentation index, reactive hyperemia, endothelin 1, plasminogen activator 1, inflammatory markers (interleukin 6, c-reactive protein), insulin secretion, insulin sensitivity (Matusda index), and disposition index (DI).

RESULTS

Thirty-two subjects had biphasic responses; 35 subjects had monophasic responses and two females had incessant increases. Sex did not affect the frequency of responses. Glucose area under the curve during OGTT was greater in those with a mono vs. biphasic curves (p=0.01). Disposition index was markedly lower in subjects with a monophasic curve than in those with a biphasic curve (3.6 [2.3-5.0] vs. 5.8 [3.8-7.6], median [25th, 75th%] p=0.003). Triglyceride to high-density lipoprotein cholesterol (HDL) ratio was higher in subjects with a monophasic curve (p=0.046).

CONCLUSIONS

The decreased disposition index indicates that in healthy adolescents a monophasic response to OGTT is due to decreased insulin secretion relative to the degree of insulin resistance present. This was not associated with differences in most other cardiometabolic risk markers.

TRIAL REGISTRATION

Clinical Trials.gov, NCT02821104.

Biomarkers of cardiometabolic complications in survivors of childhood acute lymphoblastic leukemia

Survivors of childhood acute lymphoblastic leukemia (cALL) are at higher risk of developing cardiometabolic complications. We aimed at exploring the associations between biomarkers of inflammation, oxidative stress, endothelial function, endotoxemia and cardiometabolic risk factors. We conducted a cross-sectional analysis in 246 cALL survivors (mean age, 22.1 ± 6.3 years; mean time since diagnosis, 15.5 ± 5.2 years) and evaluated the associations using a series of logistic regressions. Using structural equation models, we also tested if the relationship between endotoxemia and cardiometabolic complications was mediated by the latent (unobserved) variable inflammation inferred from the observed biomarkers CRP, TNF-α and IL-6. High leptin-adiponectin ratio was associated with obesity [adjusted OR = 15.7; 95% CI (6.2–39.7)], insulin resistance [20.6 (5.2–82.1)] and the metabolic syndrome [11.2 (2.6–48.7)]. Higher levels of plasminogen activator inhibitor-1 and tumor necrosis factor-α were associated with obesity [3.37 (1.6–7.1) and 2.34 (1.3–4.2), respectively] whereas high C-reactive protein levels were associated with insulin resistance [3.3 (1.6–6.8)], dyslipidemia [2.6 (1.4–4.9)] and MetS [6.5 (2.4–17.9)]. Our analyses provided evidence for a directional relationship between lipopolysaccharide binding protein, related to metabolic endotoxemia, inflammation and cardiometabolic outcomes. Identification of biomarkers and biological mechanisms could open new avenues for prevention strategies to minimize the long-term sequelae, improve follow-up and optimize the quality of life of this high-risk population.

Role of exercise on insulin sensitivity and beta-cell function: is exercise sufficient for the prevention of youth-onset type 2 diabetes?

Parallel with the current pediatric obesity epidemic, the escalating rates of youthonset type 2 diabetes mellitus (T2DM) have become a major public health burden. Although lifestyle modification can be the first-line prevention for T2DM in youths, there is a lack of evidence to establish optimal specific exercise strategies for obese youths at high risk for T2DM. The purpose of this narrative review is to summarize the potential impact of exercise on 2 key pathophysiological risk factors for T2DM, insulin sensitivity and β-cell function, among obese youths. The studies cited are grouped by use of metabolic tests, i.e., direct and indirect measures of insulin sensitivity and β-cell function. In general, there are an increasing number of studies that demonstrate positive effects of aerobic exercise, resistance exercise, and the 2 combined on insulin sensitivity. However, a lack of evidence exists for the effect of any exercise modality on β-cell functional improvement. We also suggest a future direction for research into exercise medical prevention of youth-onset T2DM. These suggestions focus on the effects of exercise modalities on emerging biomarkers of T2DM risk.

Myocardial functions, blood pressure changes, and arterial stiffness in children with severe hemophilia A

INTRODUCTION

Prolonging the life span of patients with hemophilia has led to the emergence of comorbidities. Cardiovascular diseases are one of the important causes of mortality in patients with hemophilia. This study investigated the myocardial functions, blood pressure changes, arterial stiffness, and risk factors associated with cardiovascular diseases in children with hemophilia.

MATERIAL AND METHODS

In total, 17 children with severe hemophilia A and 23 healthy children were included in the study. Myocardial functions were evaluated using standard and tissue Doppler echocardiography. Peripheral and central blood pressure measurements were performed, and arterial stiffness was evaluated. Carotid intima-media thicknesses (CIMT) serum glucose, insulin, insulin resistance index, and lipoprotein levels were measured.

RESULTS

There were no differences between the two groups in terms of age, and biochemical parameters (P > 0.05). The HDL-C levels in the hemophilia group were lower than those in the control group (P < 0.05). Five of the patients had insulin resistance (29.4%), whereas four had low HDL-C levels (23.5%). There were no differences between the groups in terms of the CIMT, peripheral blood pressure, and central systolic blood pressure (P > 0.05). In the hemophilia group, central diastolic blood pressure (cDBP), arterial stiffness, and myocardial performance index were higher (P < 0.05, P = 0.01, P < 0.01), whereas the ejection time was shorter than in the control group (P < 0.05).

CONCLUSIONS

Compared with the control group, there is an onset of arterial stiffness, cDBP values tend to increase, and serum HDL-C levels are lower in the hemophilia group. Moreover, myocardial systolic functions demonstrate a deterioration that becomes more prominent with the increase in arterial stiffness.

Associations Between Metabolic Profiles and Target-Organ Damage in Chinese Individuals With Primary Aldosteronism

Purpose: Patients with primary aldosteronism (PA) have an increased risk of target-organ damage (TOD), but whether metabolic syndrome (MetS) is more prevalent and contributes to TOD in PA patients remains unresolved. We aimed to evaluate the associations between MetS profiles and TOD in Chinese PA individuals. Methods: Metabolic parameters and pre-clinical TOD including left ventricular hypertrophy, estimated glomerular filtration, and microalbuminuria; insulin sensitivity or resistance; and islet β-cell function were assessed by the homeostasis models (HOMA-IR, HOMA-β) and the other surrogate indexes [composite insulin sensitivity index (ISI), modified β-cell function index (MBCI)] determined from the oral glucose tolerance test were compared in PA vs. matched essential hypertension (EH) patients. Results: A total of 109 PA patients and 109 essential hypertension (EH) controls individually matched for sex, age, and office systolic blood pressure and duration of hypertension were studied. The prevalence of MetS and its individual components in PA was significantly lower than in EH [MetS: 28 (25.6%) vs. 54 (49.5%), P < 0.001]. PA patients had a higher composite ISI but a lower HOMA-IR, HOMA-β, and MBCI than EH controls (all P < 0.05). Concerning TOD, PA patients had significantly higher prevalence of microalbuminuria and left ventricular hypertrophy (LVH), and lower levels of estimated glomerular filtration (eGFR) than EH controls (all P < 0.05). On multivariate logistic regression analysis, female gender and elevated plasma aldosterone levels were significantly associated with TOD in PA. However, there were no significant associations between MetS and its individual components and TOD in PA patients. Conclusions: PA patients had a lower MetS prevalence but exhibited more severe TOD than matched EH controls. The study highlights the deleterious effects of aldosterone excess on the development of TOD, whereas MetS or its individual components might be less influential in PA.

Increased body fat and reduced insulin sensitivity are associated with impaired endothelial function and subendocardial viability in healthy, non-Hispanic white adolescents

BACKGROUND

Cardiovascular disease has its origins in adolescents. Endothelial dysfunction, arterial stiffness, and decreased endocardial oxygen supply: demand ratios are early functional markers of cardiovascular risk. The goal of this study was to determine the relationships of these markers to physical, inflammatory, and metabolic markers in healthy non-Hispanic, white adolescents.

METHODS

Thirty-four of the 75 subjects were female. Mean age was 15.0 ± 1.7 years and mean body mass index (BMI) was 22.0 ± 5.8 kg/m² (mean ± SD). Reactive hyperemia was measured using venous occlusion plethysmography. Arterial tonometry was used to measure the augmentation index (AIx₇₅ ) and the Buckberg subendocardial viability ratio. Blood samples were taken to measure inflammatory and lipid markers and oral glucose tolerance test was used to assess insulin sensitivity.

RESULTS

Reactive hyperemia decreased as body mass and fat mass increased. It also decreased with increasing neutrophil count. The Buckberg index was higher in males and was positively related to insulin sensitivity even when accounting for age, sex, and resting heart rate. AIx₇₅ was not related to any of the other variables.

CONCLUSIONS

These results demonstrate that increased fat mass and decreased insulin sensitivity are related to poorer vascular function and cardiac risk in adolescents before the development of actual cardiovascular disease.

β-Cell function in obese children and adolescents with metabolic syndrome compared to isolated obesity

OBJECTIVE

To evaluate β-cell function in obese children and adolescents meeting clinical criteria for isolated obesity (iOB), isolated components of dysmetabolism (cMD), or metabolic syndrome (MS), and in obese children and adolescents with normal glucose tolerance (NGT), impaired glucose regulation (IGR), or type 2 diabetes (T2DM).

STUDY DESIGN

We undertook a prospective study of Han Chinese children and adolescents aged 8-16 years (median 11 ± 1.4) seen in an obesity clinic between May 2013 and 2018. Patients were classified as iOB (53), cMD (139), and MS (139) groups based on clinical criteria. The same patients were also classified as NGT (212), IGR (111), or T2DM (8) based on results of an oral glucose tolerance test (OGTT). The MS patients were classified as NGT [MS](59) and IGR [MS](72) for the further study. All participants also completed a mixed-meal tolerance test (MMTT).

RESULTS

Compared with the iOB group, the MS group had significantly higher area under the curve of C-peptide up to the 2 hours (AUC CP) (P = .03) and peak C-peptide (P = .03), adjusted for BMI, age and Tanner stage, on MMTT. However, there was no difference in the insulinogenic index (ΔI30/ΔG30) or oral disposition index (oDI) derived from the OGTT among the three groups. However, 52% of participants with MS had IGR, compared to 28% in the cMD group. Compared with the NGT group, the individuals with IGR had significantly lower ΔI30/ΔG30 (P = .001) and oDI (P < .001). Compared with the iOB group, the NGT[MS] had significantly higher AUC CP (P = .004), peak C-peptide (P = .004) and ΔI30/ΔG30 (P = .007) adjusted for age, but no difference in oDI. Compared with the NGT[MS], the IGR[MS] had significantly lower ΔI30/ΔG30 (P = .005) and oDI (P < .001), but the AUC CP and peak C-peptide had no difference.

CONCLUSION

Although the MS youth have β-cell hyperfunction as a whole, β-cell dysfunction is present in the early stages of dysmetabolism in obese youth with cMD or MS and worsened across the spectrum from iOB to cMD and MS, contributing to development of T2DM.

Vascular health determinants in children

BACKGROUND

The epidemic of cardiovascular disease (CVD) in the twentieth century generated numerous population-based surveys. These results clearly demonstrate that many factors are causally related to the development of atherosclerosis. Eighty percent of the CVD can be explained by smoking, high blood pressure, deterioration of lipid and glucose metabolism and physical inactivity. CVD is a disease that becomes clinically apparent in adults. However, it is undisputed that this disease develops over a long period of time due to progressive, subclinical changes in the cardiovascular system. The early manifestation of arteriosclerosis correlates with traditional risk factors.

METHODS

This brief report focusses on determinates of vascular health. It describes non-invasive diagnostic methods such as oscillometric analysis of pulse wave velocity (PWV), ultrasound measurement of carotid structure and function as well as brachial endothelial function. Special attention is paid to possible correlations with physical activity, fitness and exercise.

RESULTS

Non-invasive diagnostic methods to determine vascular health are applicable in children. The influence of physical activity and the relationship between aerobic fitness and arterial compliance (AC) remain controversial. First results in young athletes demonstrated an increased carotid intima-media thickness (cIMT), by revealing arterial elasticity. The mechanism and determinants explaining these adaptations have not been fully explained in young healthy athletes.

CONCLUSIONS

Traditional cardiovascular risk factors act early in life and have a major impact on the development of atherosclerosis. The results underline that the prevention strategies and risk factor control should begin in childhood. The emphasis in the present report lied on the determination of vascular health, analyzing arterial structure and function, using non-invasive diagnostic methods. Vascular health and its relation to obesity, hypertension, physical activity and exercise were emphasized. The harmonization of knowledge and methods would greatly increase the comparability of existing results. To further elucidate the clinical relevance, the mechanisms linking arterial structure and compliance function with physical activity, fitness and exercise need further clinical investigation to enhance early preventive intervention strategies.

Sex and Ethnic Differences in the Relationship between Changes in Anthropometric Measurements and Visceral Fat in Adolescents with Obesity

OBJECTIVE

To examine sex and ethnic differences in how baseline and changes in anthropometric measures relate with change in visceral fat with interventions in adolescents.

STUDY DESIGN

Black and white adolescents (n = 143: body mass index [BMI] ≥85th percentile, 12-18 years) who participated in intervention studies (3-6 months) were included and had assessments of anthropometric measures (weight, BMI, waist circumference, waist-to-hip ratio [WHR], and waist-to-thigh ratio) and visceral fat at L4-L5 by magnetic resonance imaging before and after interventions.

RESULTS

At baseline, all of the anthropometric measures were positively associated with visceral fat (P < .05), with weight, waist circumference, and WHR having the largest variance explained (model adjusted R² = 0.35-0.47 vs 0.32-0.35). Blacks had 11.5-23.3 cm² less visceral fat compared with whites for a given anthropometric value. Girls tended to have less visceral fat for a given anthropometric value, but the sex differences were not consistently significant (range: 0.7-12.9 cm²). Changes in waist circumference, BMI, and weight, but not WHR, remained significantly associated with changes in visceral fat. There were no sex differences, and much more minimal ethnic differences (<4.9 cm²).

CONCLUSIONS

At baseline, there are sex and ethnic differences in how anthropometric measures correlate with visceral fat. However, there were minimal sex and ethnic differences in how changes in anthropometric measures related with changes in visceral fat. Although all of the anthropometric measures were associated with visceral fat at baseline, waist circumference, BMI, and weight, but not WHR were associated with changes in visceral fat.

TRIAL REGISTRATION

Clinicaltrials.gov: NCT00739180, NCT01323088, and NCT01938950.

Insulin Resistance in Children

Insulin resistance (IR) is a pathological condition strongly associated with obesity. However, corticosteroids or growth hormone therapy and genetic diseases may affect insulin sensitivity lifelong. In obese children and adolescents of any age there is an evident association between IR and an increased prevalence of type 2 diabetes (T2D) and other elements contributing to the metabolic syndrome, leading to a higher cardiovascular risk. Therefore, early diagnosis and interventions in the attempt to prevent T2D when glycemia values are still normal is fundamental. The gold standard technique used to evaluate IR is the hyperinsulinemic euglycemic clamp, however it is costly and difficult to perform in clinical and research sets. Therefore, several surrogate markers have been proposed. Although the treatment of insulin resistance in children is firstly targeted to lifestyle interventions, in selected cases the integration of a pharmacological intervention might be taken into consideration. The aim of this review is to present the current knowledge on IR in children, starting with an outline of the recent evidences about the congenital forms of deficiency in insulin functioning and therefore focusing on the physiopathology of IR, its appropriate measurement, consequences, treatment options and prevention strategies.

Capsaicin in Metabolic Syndrome

Capsaicin, the major active constituent of chilli, is an agonist on transient receptor potential vanilloid channel 1 (TRPV1). TRPV1 is present on many metabolically active tissues, making it a potentially relevant target for metabolic interventions. Insulin resistance and obesity, being the major components of metabolic syndrome, increase the risk for the development of cardiovascular disease, type 2 diabetes, and non-alcoholic fatty liver disease. In vitro and pre-clinical studies have established the effectiveness of low-dose dietary capsaicin in attenuating metabolic disorders. These responses of capsaicin are mediated through activation of TRPV1, which can then modulate processes such as browning of adipocytes, and activation of metabolic modulators including AMP-activated protein kinase (AMPK), peroxisome proliferator-activated receptor α (PPARα), uncoupling protein 1 (UCP1), and glucagon-like peptide 1 (GLP-1). Modulation of these pathways by capsaicin can increase fat oxidation, improve insulin sensitivity, decrease body fat, and improve heart and liver function. Identifying suitable ways of administering capsaicin at an effective dose would warrant its clinical use through the activation of TRPV1. This review highlights the mechanistic options to improve metabolic syndrome with capsaicin.

Associations of hyperglycemia and insulin resistance with biomarkers of endothelial dysfunction in Hispanic/Latino youths: Results from the Hispanic Community Children's Health Study/Study of Latino Youth (SOL Youth)

AIMS

We hypothesized that Hispanic/Latino youth at high risk for diabetes would have elevated biomarkers of endothelial dysfunction.

METHODS

Among 1316 children 8-16years old from the Study of Latino Youth (SOL Youth), we used Poisson regression to obtain prevalence ratios (PRs) and 95% CIs for the cross-sectional association of quartiles of fasting glucose, HbA1c, and insulin resistance with E-selectin and plasminogen activator inhibitor-1 (PAI-1) levels above the median (≥48.1 and ≥2.02ng/mL, respectively).

RESULTS

Levels of E-selectin and PAI-1 were higher in children who were obese or had higher levels of hs-CRP (p<0.05). Insulin resistance was independently associated with higher levels of PAI-1 (adjusted PR and 95% CI for the highest versus lowest quartile (Q4 vs Q1): 2.25 [1.64, 3.09]). We found stronger evidence of associations of insulin resistance with higher levels of PAI-1 among boys as compared with girls (p-interaction = 0.10).

CONCLUSIONS

Insulin resistance was associated with endothelial dysfunction, as measured by higher levels of PAI-1, in Hispanic/Latino youth. These biomarkers may be useful in risk stratification and prediction of diabetes and cardiovascular disease in high-risk youth.

Adipokines, insulin resistance, and adiposity as a predictors of metabolic syndrome in child survivors of lymphoma and acute lymphoblastic leukemia of a developing country

BACKGROUND

There is a growing body of evidence indicating that pediatric survivors of cancer are at a greater risk of developing metabolic syndrome. This study evaluated some probable predictors of metabolic syndrome (MS), such as leptin and adiponectin concentrations, the leptin/adiponectin ratio, insulin resistance, and adiposity, in a sample of child survivors of lymphoma and leukemia in Mexico City.

METHODS

Fifty two children (leukemia n = 26, lymphoma n = 26), who were within the first 5 years after cessation of therapy, were considered as eligible to participate in the study. Testing included fasting insulin, glucose, adipokines and lipids; body fat mass was measured by DXA. The MS components were analyzed according to tertiles of adipokines, insulin resistance, and adiposity. Comparisons between continuous variables were performed according to the data distribution. The MS components were analyzed according to tertiles of adipokines, insulin resistance, and adiposity. With the purpose of assessing the risk of a present MS diagnosis, odds ratios (OR) with a 95% confidence interval (95% IC) were obtained using logistic regression analysis according to the various metabolic markers.

RESULTS

The median children age was 12.1 years, and the interval time from the completion of therapy to study enrollment was 4 years. Among the MS components, the prevalence of HDL-C low was most common (42%), followed by central obesity (29%). The HOMA-IR (OR 9.0, 95% CI 2.0; 41.1), body fat (OR 5.5, 95% CI 1.6; 19.3), leptin level (OR 5.7, 95% CI 1.6; 20.2) and leptin/adiponectin ratio (OR 9.4, 95% CI 2.0; 49.8) in the highest tertile, were predictive factors of developing MS; whereas the lowest tertile of adiponectin was associated with a protective effect but not significant.

CONCLUSIONS

Biomarkers such as HOMA-IR, leptin and leptin/adiponectin are associated with each of the components of the MS and with a heightened risk of suffering MS among children survivors of cancer. Given the close relationship between MS with risk of developing type 2 diabetes and cardiovascular disease, it is imperative to implement prevention measures in this population and especially in developing countries where these pathologies have become the leading cause of death.

Evaluating health risk using a continuous metabolic syndrome score in obese children

BACKGROUND

The metabolic syndrome (MS) in pediatrics is controversial. Rather than a dichotomous scale, a continuous metabolic syndrome score (cMets) has been proposed to evaluate MS. The aim of this study was to evaluate the utility of a cMets score among an ethnically diverse cohort of children with acanthosis nigricans (AN).

METHODS

A retrospective chart review was used to extract clinical and laboratory information on a cohort of obese children. Criteria for MS components and the cMets score were established using published guidelines. Multiple linear regression evaluated the effect of AN status on MS and cMets. Fisher's exact test compared the race differential on the presence or absence of MS component disorders.

RESULTS

MS diagnosis was non-significant when considering AN status (p=0.554) and ethnicity (p=0.431). Evaluation of the frequency of component disorders, revealed that Caucasians had significantly higher levels of abnormal triglycerides (TG) (35.1 vs. 10.3%; p<0.001), whereas African Americans had significantly higher homeostatic model assessment of insulin resistance (HOMA-IR) scores (51.3% vs. 22.3%; p<0.001). cMets was sensitive to identifying metabolic risk among Caucasians with AN, only (p=0.029).

CONCLUSIONS

This study found differences in health risk among an obese, ethnically diverse sample of children. cMets is a more sensitive marker of metabolic change compared with MS, especially when AN status and race are considered. cMets may pose an opportunity for the clinician to evaluate the interaction of health risks on the health status of obese children.

Distinguishing characteristics of metabolically healthy versus metabolically unhealthy obese adolescent girls with polycystic ovary syndrome

OBJECTIVE

To investigate the key physical, metabolic, hormonal and cardiovascular characteristics of metabolically healthy obese (MHO) versus unhealthy obese (MUHO) girls with polycystic ovary syndrome (PCOS).

DESIGN

Cross-sectional study.

SETTING

Research center.

PATIENT(S)

Seventy obese girls with PCOS were divided into 19 MHO and 51 MUHO based on cutoff points for in vivo insulin sensitivity (within and < 2 SDs of the mean of the insulin sensitivity of the normal-weight girls, respectively).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Body composition, abdominal fat, in vivo insulin sensitivity and secretion (hyperinsulinemic-euglycemic and hyperglycemic clamps respectively), hormonal profile, and cardiovascular disease risk markers.

RESULT(S)

MUHO-PCOS girls had higher waist circumference, visceral adipose tissue, leptin, and free testosterone, lower SHBG and E2, higher non-high-density lipoprotein (HDL) cholesterol and atherogenic lipoprotein particle concentrations, smaller HDL particle size, and higher high-sensitivity C-reactive protein compared with MHO-PCOS girls. Hepatic and peripheral insulin sensitivity were lower with higher first- and second-phase insulin secretion, but β-cell function relative to insulin sensitivity was lower in MUHO versus MHO. Pair matching of MHO and MUHO regarding age and body mass index revealed similar findings. MUHO-PCOS girls had larger visceral adiposity, lower insulin sensitivity and β-cell function, worse hormonal profile, and severely atherogenic lipoprotein concentrations compared with MHO-PCOS girls.

CONCLUSION(S)

MHO-PCOS girls have favorable physical, metabolic, hormonal, and cardiovascular disease (CVD) characteristics and lower risk biomarkers for type 2 diabetes compared with their MUHO-PCOS peers. A greater understanding of the contrast in this risk phenotype in obese girls with PCOS may have important implications for therapeutic interventions, their outcomes, and their durability.

Impact of a community based health-promotion programme in 2- to 9-year-old children in Europe on markers of the metabolic syndrome, the IDEFICS study

INTRODUCTION

One objective of 'Identification and prevention of Dietary-and lifestyle-induced health EFfects In Children and infantS', the IDEFICS study, was to implement a community-oriented childhood obesity prevention intervention in eight European countries.

OBJECTIVE

To assess the effect of an obesity primary prevention programme on metabolic markers.

METHODS

The study had a non-randomized cluster-experimental design. In each country, children were recruited from distinct communities serving as intervention and control regions. Health examinations were done during 2007-2008 before the intervention (T0 ) and during 2009-2010 (T1 ). Children with results available from T0 and T1 on blood pressure, waist circumference and at least one blood-marker (fasting glucose, insulin, HOMA-IR, HbA1c, HDL- and LDL-cholesterol, triglycerides, C-reactive protein) were included. A metabolic syndrome (MetS) score was calculated.

RESULTS

A total of 7,406 children (age 2-9.9 years) of the 16,228 participating at T0 provided the necessary data. No effect of the intervention was seen on insulin, HOMA-IR, CRP or the MetS score. Overall fasting glucose increased less in the intervention than in the control region, a pattern driven by three of the eight countries and more pronounced in children of parents with low education. Overall, HbA1c and waist circumference increased more and blood pressure less in the intervention regions.

CONCLUSION

We observed no convincing effect of the intervention on markers of the metabolic syndrome. We identified diverse patterns of change for several markers of uncertain relation to the intervention.

The changing face of diabetes in youth: lessons learned from studies of type 2 diabetes

The incidence of youth type 2 diabetes (T2D), linked with obesity and declining physical activity in high-risk populations, is increasing. Recent multicenter studies have led to a number of advances in our understanding of the epidemiology, pathophysiology, diagnosis, treatment, and complications of this disease. As in adult T2D, youth T2D is associated with insulin resistance, together with progressive deterioration in β cell function and relative insulin deficiency in the absence of diabetes-related immune markers. In contrast to adult T2D, the decline in β cell function in youth T2D is three- to fourfold faster, and therapeutic failure rates are significantly higher in youth than in adults. Whether the more aggressive nature of youth T2D is driven by genetic heterogeneity or physiology/metabolic maladaptation is yet unknown. Besides metformin, the lack of approved pharmacotherapeutic agents for youth T2D that target the pathophysiological mechanisms is a major barrier to optimal diabetes management. There is a significant need for effective therapeutic options, in addition to increased prevention, to halt the projected fourfold increase in youth T2D by 2050 and the consequences of heightened diabetes-related morbidity and mortality at younger ages.

Vascular cell adhesion molecule-1, but not intercellular adhesion molecule-1, is associated with diabetic kidney disease in Asians with type 2 diabetes

BACKGROUND AND AIMS

The association of adhesion molecules ICAM-1 and VCAM-1 with cardiovascular diseases has been well-studied. However, their roles in diabetic kidney disease (DKD) are incompletely understood. We aim to study the association of plasma ICAM-1 and VCAM-1 with DKD in Asians with type 2 diabetes (T2DM).

SUBJECTS AND METHODS

A total of 1950 Asians with T2DM were included in this cross-sectional study. Plasma ICAM-1 and VCAM-1 were measured by immunoassays.

RESULTS

Renal filtration function (eGFR) declined and urinary albumin-to-creatinine ratio (ACR) levels increased progressively with the increase in plasma VCAM-1 levels. In contrast, no significant changes in eGFR and ACR were observed in subjects across different plasma ICAM-1 levels. Both ICAM-1 and VCAM-1 were correlated with ACR (rho = 0.153, p < 0.001 for VCAM-1 and ACR; rho = 0.053, p = 0.020 for ICAM-1 and ACR) in bivariate correlation analysis. However, only VCAM-1 was correlated with eGFR (rho = -0.228, p < 0.001). Multivariable linear regression models revealed that VCAM-1, but not ICAM-1, was independently associated with eGFR and albuminuria. Backward linear regression suggested that plasma VCAM-1 variability was mainly determined by eGFR whereas plasma ICAM-1 level was mainly determined by C-reactive protein in patients with T2DM.

CONCLUSIONS

Plasma VCAM-1 level, but not ICAM-1 level, was independently associated with prevalent DKD in Asians with T2DM. High level of ICAM-1 may be indicative of systemic inflammation and portends increase risk of incipient DKD.

The Diagnosis of Polycystic Ovary Syndrome during Adolescence

BACKGROUND/AIMS

The diagnostic criteria for polycystic ovary syndrome (PCOS) in adolescence are controversial, primarily because the diagnostic pathological features used in adult women may be normal pubertal physiological events. Hence, international pediatric and adolescent specialty societies have defined criteria that have sufficient evidence to be used for the diagnosis of PCOS in adolescents.

METHODS

The literature has been reviewed and evidence graded to address a series of questions regarding the diagnosis of PCOS during adolescence including the following: clinical and biochemical evidence of hyperandrogenism, criteria for oligo-anovulation and polycystic ovary morphology, diagnostic criteria to exclude other causes of hyperandrogenism and amenorrhea, role of insulin resistance, and intervention.

RESULTS AND CONCLUSION

Features of PCOS overlap normal pubertal development. Hence, caution should be taken before diagnosing PCOS without longitudinal evaluation. However, treatment may be indicated even in the absence of a definitive diagnosis. While obesity, insulin resistance, and hyperinsulinemia are common findings in adolescents with hyperandrogenism, these features should not be used to diagnose PCOS among adolescent girls. © 2015 S. Karger AG, Basel.

Pre-diabetes in overweight youth and early atherogenic risk

PURPOSE

To compare atherogenic lipoprotein particles and vascular smooth muscle biomarkers in overweight youth with pre-diabetes (PD) vs. normal glucose tolerance (NGT).

METHODS

144 adolescents (60 black, 84 white; 102 female; PD=45, NGT=99) aged 10-19 years underwent a fasting blood draw and 2-h OGTT. Lipoprotein particle size and subclass concentration and vascular smooth muscle biomarkers (ICAM-1, VCAM-1 and E-selectin) were compared between youth with PD and NGT.

RESULTS

Compared with NGT, PD adolescents had smaller LDL (mean±SE: 20.5±0.1 vs. 21.0±0.1 nm; P=0.002) and HDL (8.62±0.05 vs. 8.85±0.04 nm; P=0.013) size and elevated medium small (159.2±10.3 vs. 123.8±6.4 nmol/L; P=0.037) and very small (626.3±45.4 vs. 458.5±26.4 nmol/L; P=0.032) LDL particle concentrations, after adjustment for race and BMI. Further adjusting for fasting insulin or visceral adiposity obviated these differences between the groups except for LDL size. ICAM-1 and E-selectin did not differ in youth with PD but correlated with LDL and HDL size, and small LDL particle concentrations.

CONCLUSIONS

Overweight adolescents with PD have an atherogenic lipoprotein profile of small LDL and HDL size and increased concentrations of small LDL, moderated by insulin resistance and visceral adiposity, but independently driven by dysglycemia for LDL size. Associations between smooth muscle biomarkers and lipoproteins could be an early signal heralding the atherogenic process. It remains to be determined if correction of dysglycemia and associated lipoprotein abnormalities in obese youth could prove effective in halting this process.

Endocrinology and Adolescence: aerobic exercise reduces insulin resistance markers in obese youth: a meta-analysis of randomized controlled trials

OBJECTIVE

The purpose of this meta-analysis was to examine the evidence for the effectiveness of aerobic exercise interventions on reducing insulin resistance markers in obese children and/or adolescents. A secondary outcome was change in percentage of body fat.

METHODS

A computerized search was made from seven databases: CINAHL, Cochrane Central Register of Controlled Trials, EMBASE, ERIC, MEDLINE, PsycINFO, and Science Citation Index. The analysis was restricted to randomized controlled trials that examined the effect of aerobic exercise on insulin resistance markers in obese youth. Two independent reviewers screened studies and extracted data. Effect sizes (ES) and 95% confidence interval (CI) were calculated, and the heterogeneity of the studies was estimated using Cochran's Q-statistic.

RESULTS

Nine studies were selected for meta-analysis as they fulfilled the inclusion criteria (n=367). Aerobic exercise interventions resulted in decreases in fasting glucose (ES=-0.39; low heterogeneity) and insulin (ES=-0.40; low heterogeneity) and in percentage of body fat (ES=-0.35; low heterogeneity). These improvements were specifically accentuated in adolescents (only in fasting insulin), or through programs lasting more than 12 weeks, three sessions per week, and over 60 min of aerobic exercise per session.

CONCLUSIONS

This meta-analysis provides insights into the effectiveness of aerobic exercise interventions on insulin resistance markers in the obese youth population.

Coronary artery calcification in obese youth: what are the phenotypic and metabolic determinants?

OBJECTIVE

Obesity in adolescence has been associated with increased risk for coronary heart disease in adulthood. This study evaluated subclinical atherosclerosis in obese youth and the underlying risk factors.

RESEARCH DESIGN AND METHODS

Ninety obese adolescents (37 normal glucose tolerant, 27 prediabetes, and 26 type 2 diabetes) underwent evaluation of coronary artery calcifications (CACs) by electron beam computed tomography, aortic pulse wave velocity (PWV), carotid intima-media thickness (IMT), lipids, leptin, inflammatory markers, and body composition (DEXA). A total of 68 underwent evaluation of insulin sensitivity (IS) (hyperinsulinemic-euglycemic clamp) and abdominal adiposity (computed tomography).

RESULTS

A total of 50% had CACs (CAC+: Agatston CAC score ≥1). CAC+ youth had higher BMI, fat mass, and abdominal fat, with no difference in sex, race, IS per fat-free mass (ISFFM), glucose tolerance, PWV, or IMT compared with the CAC- group. PWV was inversely related to IS. In multiple regression analyses with age, race, sex, HbA1c, BMI (or waist circumference), ISFFM, diastolic blood pressure, non-HDL cholesterol, and leptin as independent variables, BMI (or waist) (R(2) = 0.41; P = 0.001) was the significant determinant of CAC; leptin (R(2) = 0.37; P = 0.034) for PWV; and HbA1c, race, and age (R(2) = 0.34; P = 0.02) for IMT.

CONCLUSIONS

Early in the course of obesity, there is evidence of CAC independent of glycemia. The different biomarkers of subclinical atherosclerosis appear to be differentially modulated, adiposity being the major determinant of CAC, hyperglycemia, age, and race for IMT, and leptin and IS for arterial stiffness. These findings highlight the increased cardiovascular disease risk in obese youth and the need for early interventions to reverse obesity and atherosclerosis.

Prepubertal children with a history of extra-uterine growth restriction exhibit low-grade inflammation

Intra-uterine growth restriction (IUGR) may induce significant metabolic and inflammatory anomalies, increasing the risk of obesity and CVD later in life. Similarly, alterations in the adipose tissue may lead to metabolic changes in children with a history of extra-uterine growth restriction (EUGR). These mechanisms may induce alterations in immune response during early life. The aim of the present study was to compare pro-inflammatory markers in prepubertal EUGR children with those in a reference population. A total of thirty-eight prepubertal children with a history of EUGR and a reference group including 123 healthy age- and sex-matched children were selected. Perinatal data were examined. In the prepubertal stage, the concentrations of inflammatory biomarkers were measured in both groups. The serum concentrations of C-reactive protein (CRP) and plasma concentrations of hepatocyte growth factor (HGF), IL-6, IL-8, monocyte chemotactic protein type 1 (MCP-1), neural growth factor, TNF-α and plasminogen activator inhibitor type 1 were determined. The plasma concentrations of inflammatory biomarkers CRP, HGF, IL-8, MCP-1 and TNF-α were higher in the EUGR group than in the reference group (P< 0·001). After adjustment for gestational age, birth weight and length, blood pressure values and TNF-α concentrations remained higher in the EUGR group than in the reference group. Therefore, further investigations should be conducted in EUGR children to evaluate the potential negative impact of metabolic, nutritional and pro-inflammatory changes induced by the EUGR condition.

Low sensitivity of the metabolic syndrome to identify adolescents with impaired glucose tolerance: an analysis of NHANES 1999-2010

BACKGROUND

The presence of impaired glucose tolerance (IGT) and metabolic syndrome (MetS) are two risk factors for Type 2 diabetes. The inter-relatedness of these factors among adolescents is unclear.

METHODS

We evaluated the sensitivity and specificity of MetS for identifying IGT in an unselected group of adolescents undergoing oral glucose tolerance tests (OGTT) in the National Health and Nutrition Evaluation Survey 1999-2010. We characterized IGT as a 2-hour glucose ≥140 mg/dL and MetS using ATP-III-based criteria and a continuous sex- and race/ethnicity-specific MetS Z-score at cut-offs of +1.0 and +0.75 standard deviations (SD) above the mean.

RESULTS

Among 1513 adolescents, IGT was present in 4.8%, while ATP-III-MetS was present in 7.9%. MetS performed poorly in identifying adolescents with IGT with a sensitivity/specificity of 23.7%/92.9% for ATP-III-MetS, 23.6%/90.8% for the MetS Z-score at +1.0 SD and 35.8%/85.0 for the MetS Z-score at +0.75 SD. Sensitivity was higher (and specificity lower) but was still overall poor among overweight/obese adolescents: 44.7%/83.0% for ATP-III-MetS, 43.1%/77.1% for the MetS Z-score at +1.0 SD and 64.3%/64.3% for MetS Z-score at +0.75 SD.

CONCLUSION

This lack of overlap between MetS and IGT may indicate that assessment of MetS is not likely to be a good indicator of which adolescents to screen using OGTT. These data further underscore the importance of other potential contributors to IGT, including Type 1 diabetes and genetic causes of poor beta-cell function. Practitioners should keep these potential causes of IGT in mind, even when evaluating obese adolescents with IGT.

Aerobic exercise and weight loss reduce vascular markers of inflammation and improve insulin sensitivity in obese women

OBJECTIVES

To examine the relationships between plasma and tissue markers of systemic and vascular inflammation and obesity and insulin resistance and determine the effects of aerobic exercise training plus weight loss (AEX+WL) and weight loss (WL) alone on these biomarkers.

DESIGN

Prospective controlled study.

SETTING

Veterans Affairs Medical Center and University research setting.

PARTICIPANTS

Overweight and obese sedentary postmenopausal women (N = 77).

INTERVENTIONS

Six months, 3 d/wk AEX+WL (n = 37) or WL (n = 40).

MEASUREMENTS

Total-body dual-energy X-ray absorptiometry, abdominal computed tomography, hyperinsulinemic-euglycemic clamps (a criterion standard method of assessing insulin sensitivity), adipose tissue biopsies (n = 28), and blood for homeostasis model assessment-insulin resistance, and soluble forms of intracellular adhesion molecule 1 (sICAM-1) and vascular cell adhesion molecule 1 (sVCAM-1), C-reactive protein (CRP), and serum amyloid A (SAA).

RESULTS

Body weight (P < .001), percentage of fat (P < .001), visceral fat (P < .005), triglyceride levels (P < .001), and systolic blood pressure decreased comparably after WL and AEX+WL (P = .04). Maximal oxygen consumption increased 16% after AEX+WL (P < .001). Insulin resistance decreased in both groups (P = .005). Glucose utilization according to the clamp increased 10% (P = .04) with AEX+WL and 8% with WL (P = .07). AEX+WL decreased CRP by 29% (P < .001) and WL by 21% (P = .02). SAA levels decreased twice as much after AEX+WL (-19%, P = .02) as after WL (-9%, P = .08). Plasma sICAM-1 and sVCAM-1 levels did not change, but women with the greatest reduction in plasma sICAM-1 levels had the greatest reductions in fasting glucose (P = .02), insulin (P = .02), and insulin resistance (P = .004). Gluteal ICAM messenger ribonucleic acid levels decreased 27% after AEX+WL (P = .02) and did not change after WL.

CONCLUSION

Obesity and insulin resistance worsen markers of systemic and vascular inflammation. A reduction in plasma sICAM-1 is important to improve insulin sensitivity. CRP, SAA, and tissue ICAM decrease with exercise and weight loss, suggesting that exercise training is a necessary component of lifestyle modification in obese postmenopausal women.

Aerobic exercise but not resistance exercise reduces intrahepatic lipid content and visceral fat and improves insulin sensitivity in obese adolescent girls: a randomized controlled trial

It is unclear whether regular exercise alone (no caloric restriction) is a useful strategy to reduce adiposity and obesity-related metabolic risk factors in obese girls. We examined the effects of aerobic (AE) vs. resistance exercise (RE) alone on visceral adipose tissue (VAT), intrahepatic lipid, and insulin sensitivity in obese girls. Forty-four obese adolescent girls (BMI ≥95th percentile, 12-18 yr) with abdominal obesity (waist circumference 106.5 ± 11.1 cm) were randomized to 3 mo of 180 min/wk AE (n = 16) or RE (n = 16) or a nonexercising control group (n = 12). Total fat and VAT were assessed by MRI and intrahepatic lipid by proton magnetic resonance spectroscopy. Intermuscular AT (IMAT) was measured by CT. Insulin sensitivity was evaluated by a 3-h hyperinsulinemic (80 mU·m(2)·min(-1)) euglycemic clamp. Compared with controls (0.13 ± 1.10 kg), body weight did not change (P > 0.1) in the AE (-1.31 ± 1.43 kg) and RE (-0.31 ± 1.38 kg) groups. Despite the absence of weight loss, total body fat (%) and IMAT decreased (P < 0.05) in both exercise groups compared with control. Compared with control, significant (P < 0.05) reductions in VAT (Δ-15.68 ± 7.64 cm(2)) and intrahepatic lipid (Δ-1.70 ± 0.74%) and improvement in insulin sensitivity (Δ0.92 ± 0.27 mg·kg(-1)·min(-1) per μU/ml) were observed in the AE group but not the RE group. Improvements in insulin sensitivity in the AE group were associated with the reductions in total AT mass (r = -0.65, P = 0.02). In obese adolescent girls, AE but not RE is effective in reducing liver fat and visceral adiposity and improving insulin sensitivity independent of weight loss or calorie restriction.

Lifestyle intervention improves lipoprotein particle size and distribution without weight loss in obese Latino adolescents

Childhood obesity is associated with a pro-atherogenic phenotype contributing to increased cardiovascular disease (CVD) risk. This single-arm pilot study examined the effects of a lifestyle intervention on lipoprotein particle size and cholesterol distribution in obese Latino adolescents. Fifteen obese Latino adolescents (15.0 ± 1.0 years) completed a 12-week nutrition education and exercise intervention. Low-density lipoprotein (LDL) particle size and distribution of cholesterol in lipoprotein subclasses were determined via polyacrylamide gel electrophoresis. The intervention resulted in increases in mean LDL particle size (269.3 ± 3.4 to 271.6 ± 2.9 Å, P = 0.0003) and cholesterol in large high-density lipoprotein (HDL) subfractions (22.4 ± 11.2 to 26.8 ± 10.6% area, P = 0.007) along with decreases of cholesterol in small LDL (1.6 ± 2.0 to 0.6 ± 1.2% area, P < 0.01) and HDL subfractions (23.2 ± 9.4 to 19.0 ± 6.7% area, P = 0.05). These improvements were observed independent of changes in weight (90.7 ± 26.2 to 89.9 ± 27.8 kg, P > 0.05) and suggest that lifestyle modification in obese youth may reduce cardiovascular risk by shifting lipoprotein particle size and cholesterol distribution to a less atherogenic phenotype.

Effects of exercise alone on insulin sensitivity and glucose tolerance in obese youth

As with the dramatic increases in childhood obesity over the past decades, the incidence of type 2 diabetes has increased among children and adolescents in the United States. Insulin resistance is a common feature of childhood obesity and increases the risk of type 2 diabetes, metabolic syndrome, and atherogenic lipoprotein profile in obese youth. Although cross-sectional studies report beneficial effects of physical activity or cardiorespiratory fitness on insulin sensitivity, the role of regular exercise alone (e.g., no calorie restriction) as a strategy to reduce the risk of type 2 diabetes is unclear in obese children and adolescents. In this mini review, we examined the independent effects of various exercise on glucose tolerance and insulin sensitivity in obese youth.

Effects of acute exercise on postprandial triglyceride response after a high-fat meal in overweight black and white adolescents

OBJECTIVE

We examined the effects of acute exercise on postprandial triglyceride (TG) metabolism following a high-fat meal in overweight black vs white adolescents.

DESIGN AND SUBJECTS

Twenty-one black and 17 white adolescents (12-18 yrs, body mass index 85th percentile) were evaluated twice, during control versus exercise trials, 1-4 weeks apart, in a counterbalanced randomized design. In the control trial, participants performed no exercise on day 1. In the exercise trial, participants performed a single bout of 60-min exercise (50% VO2 peak) on a cycle ergometer on day 1. On day 2 of both trials, participants consumed a high-fat breakfast (70% calories from fat) and blood was sampled for TG concentration in the fasted state and for 6 h postprandially.

RESULTS

There was a significant main effect of condition on postprandial peak TG concentration (P=0.01) and TG area under the curve (AUC) (P=0.003), suggesting that independent of race, peak TG and TG-AUC was lower in the exercise trial vs control trial. Including Tanner stage, gender, total fat (kg) and visceral adipose tissue (VAT) as independent variables, stepwise multiple regression analyses revealed that in whites, VAT was the strongest (P<0.05) predictor of postprandial TG-AUC, explaining 56 and 25% of the variances in TG-AUC in the control and exercise trials, respectively. In blacks, VAT was not associated with postprandial TG-AUC, independent of trial.

CONCLUSION

A single bout of aerobic exercise preceding a high-fat meal is beneficial to reduce postprandial TG concentrations in overweight white adolescents to a greater extent than black adolescents, particularly those with increased visceral adiposity.

The study of soluble intercellular adhesion molecule-1 and ghrelin in adolescents with family history of type 2 diabetes

The purpose of this study was to observe both the changes of soluble intercellular adhesion molecule-1 (sICAM-1) and ghrelin in adolescents with family history of type 2 diabetes (FHD) and the relationship between sICAM-1 and ghrelin. This case-control study included 63 adolescents (boys/girls 29/34, age 14.1 ± 0.7 years) without FHD (FHD-) and 67 adolescents (boys/girls 33/34, age 14.0 ± 0.8 years) with FHD (FHD+). Anthropometric measurements, including height, weight, waist circumference (WC), and blood pressure, were obtained. Blood samples were collected, and fasting plasma glucose (FPG), serum lipids, true insulin, sICAM-1, and ghrelin were assayed. The results showed that the age and gender were similar in two groups (P > 0.05). Body mass index (BMI), WC, FPG, fasting insulin, HOMA-IR, and sICAM-1 were all significantly higher in the FHD+ group than in the FHD- group (P < 0.05). Ghrelin was significantly lower in the FHD+ group than in the FHD- group (P < 0.05). sICAM-1 was positively correlated with WC (r = 0.178, P = 0.043), fasting insulin (r = 0.195, P = 0.026), HOMA-IR (r = 0.197, P = 0.024), and ghrelin (r = 0.290, P = 0.001). After multivariate analysis, the ghrelin (β = 0.788, 95 % CI: 0.416-1.159, P = 0.000) and HOMA-IR (β = 0.106, 95 % CI: 0.045-0.167, P = 0.001) maintained an independent association with sICAM-1. These findings led to the conclusion that endothelial dysfunction and decline of ghrelin were found in adolescents with family history of diabetes. The decline of ghrelin maybe a protection mechanism for endothelial function in adolescents with family history of diabetes and should be examined in future studies.

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.

Postprandial endothelial function does not differ in women by race: an insulin resistance paradox?

Insulin resistance is associated with endothelial dysfunction. Because African-American women are more insulin-resistant than white women, it is assumed that African-American women have impaired endothelial function. However, racial differences in postprandial endothelial function have not been examined. In this study, we test the hypothesis that African-American women have impaired postprandial endothelial function compared with white women. Postprandial endothelial function following a breakfast (20% protein, 40% fat, and 40% carbohydrate) was evaluated in 36 (18 African-American women, 18 white women) age- and body mass index (BMI)-matched (age: 37 ± 11 yr; BMI: 30 ± 6 kg/m(2)) women. Endothelial function, defined by percent change in brachial artery flow-mediated dilation (FMD), was measured at 0, 2, 4, and 6 h following a meal. There were no significant differences between the groups in baseline FMD, total body fat, abdominal visceral fat, and fasting levels of glucose, insulin, total cholesterol, low-density lipoprotein cholesterol, or serum estradiol. Although African-American women were less insulin-sensitive [insulin sensitivity index (mean ± SD): 3.6 ± 1.5 vs. 5.2 ± 2.6, P = 0.02], both fasting triglyceride (TG: 56 ± 37 vs. 97 ± 49 mg/dl, P = 0.007) and incremental TG area under the curve (AUC(0-6hr): 279 ± 190 vs. 492 ± 255 mg·dl(-1)·min(-1)·10(-2), P = 0.008) were lower in African-American than white women. Breakfast was associated with a significant increase in FMD in whites and African-Americans, and there was no significant difference in postprandial FMD between the groups (P > 0.1 for group × time interactions). Despite being insulin-resistant, postprandial endothelial function in African-American women was comparable to white women. These results imply that insulin sensitivity may not be an important determinant of racial differences in endothelial function.

Is adipose tissue metabolically different at different sites?

This review focuses on metabolic differences of adipose tissue at different sites of the body, with emphasis in pediatrics. Adipose tissue is composed of various cell types, which include adipocytes and other cells of the stromal vascular fraction such as preadipocytes, blood cells, endothelial cells and macrophages. Mammals have two main types of adipose tissue: white adipose tissue (WAT), and brown adipose tissue (BAT), each of which possesses unique cell autonomous properties. WAT and BAT differ at the functional, as well as the morphological and molecular levels. WAT accumulates surplus energy mainly in the form of triacylglycerols and BAT dissipates energy directly as heat. Recently, functional BAT in humans has been located in the neck, supraclavicular, mediastinal and interscapular areas. WAT is distributed throughout the body in the form of two major types: subcutaneous adipose tissue (SWAT) and the intra-abdominal visceral adipose tissue (VWAT). VWAT tissue is associated with insulin resistance, diabetes mellitus, dyslipidaemia, hypertension, atherosclerosis, hepatic steatosis, and overall mortality whereas SWAT and BAT have intrinsic beneficial metabolic properties. Subcutaneous and visceral adipocytes derive from different progenitor cells that exhibit a different gene expression pattern. SWAT responds better to the antilipolytic effects of insulin and other hormones, secrets more adiponectin and less inflammatory cytokines, and is differentially affected by molecules involved in signal transduction as well as drugs compared with VWAT. Current research is investigating various approaches of BAT and SWAT transplantation, including new sources of adipocyte progenitors. This may be important for the potential treatment of childhood obesity.

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.

Dietary intakes of urban, high body mass index, African American children: family and child dietary attributes predict child intakes

OBJECTIVE

To identify family and child nutrition and dietary attributes related to children's dietary intakes.

DESIGN

African American children (ages 8-11 years, n = 156), body mass index > 85th percentile, from urban, low-income neighborhoods. Baseline, cross-sectional data collected as part of an ongoing diabetes prevention intervention. Dietary intakes were collected by 3-day food diary to assess total energy, percent fat, discretionary fat, added sugar, whole grains, vegetables, fruit, meat, and dairy. Questionnaires on nutrition and dietary attributes administered to children and parents were used to develop 5 diet-related indices: child knowledge, child preferences, child snack habits, child beverage habits, and family food habits.

RESULTS

A higher child nutrition knowledge score was significantly related to a lower starchy vegetable intake. Higher scores on the child snack habits index were significantly related to higher intakes of fruit, total fruits and vegetables, total fruits and nonstarchy vegetables, and to lower intakes of added sugars. A higher score on the family food habits index was significantly related to lower intakes of total energy and discretionary fat.

CONCLUSIONS AND IMPLICATIONS

Targeting both child and family food and nutrition attributes may be used to promote more healthful eating among urban, low-income, overweight African American children.

Vitamin D status, adiposity, and lipids in black American and Caucasian children

OBJECTIVE

The aim of the study was to examine the relationship between vitamin D status, total and abdominal adiposity, and lipids in black and white children.

METHODS

Plasma 25-hydroxyvitamin D [25(OH)D], adiposity [body mass index (BMI), percentage of total body fat, visceral adipose tissue (VAT), sc adipose tissue (SAT)], and fasting lipids were assessed in healthy obese and nonobese 8- to 18-yr-old black and white children.

RESULTS

We studied 237 children (mean ± sd age, 12.7 ± 2.2 yr; 47% black, 47% obese, and 43% male). Mean 25(OH)D concentration for the entire cohort was 19.4 ± 7.4 ng/ml. The majority of the children were vitamin D deficient [25(OH)D < 20 ng/ml; 73% blacks, 40% whites]. Plasma 25(OH)D was associated inversely with BMI, BMI percentile, percentage of total body fat, VAT, and SAT and positively with HDL cholesterol in the entire cohort. VAT was higher in vitamin D-deficient whites, and SAT was higher in vitamin D-deficient blacks compared with their respective vitamin D-nondeficient counterparts. Race, season, pubertal status, and VAT were independent significant predictors of 25(OH)D status.

CONCLUSIONS

In black and white youth examined together, lower levels of 25(OH)D are associated with higher adiposity measures and lower HDL. Furthermore, vitamin D deficiency is associated with higher VAT in whites and greater SAT in blacks. Besides therapeutic interventions to correct the high rates of vitamin D deficiency in youth, benefits of vitamin D optimization on adiposity measures and lipid profile need to be explored.

Drospirenone/ethinyl estradiol versus rosiglitazone treatment in overweight adolescents with polycystic ovary syndrome: comparison of metabolic, hormonal, and cardiovascular risk factors

CONTEXT

Adolescents with polycystic ovary syndrome (PCOS) have insulin resistance and higher rates of the metabolic syndrome.

OBJECTIVE

Our objective was to compare the effects of 6 months treatment with drospirenone/ethinyl estradiol (EE) (3 mg/30 μg) vs. rosiglitazone (4 mg) daily on the hormonal and cardiometabolic profiles of overweight/obese adolescents with PCOS.

DESIGN

We conducted a randomized, double-blinded, parallel clinical trial in an academic hospital, with n = 46 patients.

OUTCOME MEASURES

The primary outcome measure was insulin sensitivity, hepatic with [6,6-(2)H(2)]glucose and peripheral with a 3-h hyperinsulinemic-euglycemic clamp. Other outcome measures included plasma androgen profile and response to ACTH stimulation, glucose and insulin response to oral glucose tolerance test, insulin secretion with a 2-h hyperglycemic clamp, fasting lipid profile, inflammatory markers, intima media thickness, aortic pulse wave velocity, body composition by dual-energy x-ray absorptiometry, and abdominal adiposity by computed tomography scan.

RESULTS

Drospirenone/EE resulted in greater reductions in androgenemia. Neither treatment led to change in weight or body mass index, but rosiglitazone led to a significant decrease in visceral adiposity. Compared with drospirenone/EE, treatment with rosiglitazone improved hepatic and peripheral insulin sensitivity and lowered fasting and stimulated insulin levels during the oral glucose tolerance test. Treatment with drospirenone/EE was associated with elevations in total cholesterol, high-sensitivity C-reactive protein and leptin concentrations, whereas treatment with rosiglitazone led to lower triglycerides and higher adiponectin concentrations. Neither treatment affected intima media thickness or pulse wave velocity.

CONCLUSIONS

In overweight/obese adolescents with PCOS, 6 months treatment with rosiglitazone was superior to drospirenone/EE in improving the cardiometabolic risk profile, and effective but inferior in attenuating hyperandrogenemia. Additional studies are needed to test insulin sensitizers in the treatment of the reproductive and cardiometabolic aspects of PCOS.

Measurement site of visceral adipose tissue and prediction of metabolic syndrome in youth

OBJECTIVE

It is unknown whether measurement site of visceral adipose tissue (VAT) influences the relationship between VAT and associated health risk in youth and if so, whether ethnic differences exist in this relationship. We examined the influence of the measurement site of VAT on the relationships between VAT and metabolic syndrome (MetS) in African-American (AA) and American-White (AW) youth.

SUBJECTS

Healthy AA (n = 54) and AW (n = 54) children and adolescents (age: 8-18 yr; BMI: 15.3-42.5 kg/m(2)).

MEASUREMENTS

VAT mass was derived using a series of five transverse images measured by magnetic resonance imaging, extending from 5 cm below to 15 cm above L4-L5. MetS was defined using a modified IDF criteria.

RESULTS

In AA, VAT measure at 5 cm above L4-L5 (R(2) = 0.93) was most strongly (p < 0.05) correlated with VAT mass and was a significantly (p < 0.05) stronger correlate as compared to L4-L5 (R(2) = 0.84). In AW, VAT measures at 5 cm (R(2) = 0.93) and 10 cm (R(2) = 0.93) above L4-L5 were most strongly (p < 0.05) correlated with VAT mass; however, these were not stronger correlates as compared to L4-L5 (R(2) = 0.91). In AW, all VAT measures were significantly (p < 0.05) associated with an increased odds ratio (OR) for prevalent MetS, wherein the VAT mass [OR = 5.32(1.9-15.0)] and VAT at L4-L5[OR = 5.99(1.9-18.4)] were most strongly associated with MetS. In contrast, only VAT at 10 cm above L4-L5 [OR = 4.39 (1.1-18.1)] was significantly (p < 0.05) associated with MetS in AA.

CONCLUSION

In AA and AW youth, the measurement site for VAT has impact on the estimation of total VAT and the magnitude of the association with obesity-related health risks.

Whole-body MRI and ethnic differences in adipose tissue and skeletal muscle distribution in overweight black and white adolescent boys

It is unclear whether ethnic differences exist in adipose tissue (AT) and skeletal muscle (SM) distribution in black and white youth. Investigation into the pattern of AT and SM distribution in black versus white youth may provide insight into the previously reported health disparities between these ethnicities. Therefore, we examined total and regional AT and SM in overweight black and white boys. The study sample included overweight black (n = 19) and white (n = 21) boys (11-18 yr, BMI ≥ 85th) whose body composition was evaluated using whole-body MRI. Despite similar age, Tanner stage, and BMI, black boys had significantly (P < .05) less visceral AT than white boys and more (P < .05) total and lower-body subcutaneous AT (SAT) in both absolute (kg) and relative (%) terms. There was a main effect (P < .05) of ethnicity on the relationship between total and regional AT, such that for a given amount of total body AT (kg), black boys had a greater (P < .05) lower-body SAT and less visceral AT than their white peers. For a given amount of total SM, black boys had more (P < .05) SM in the thigh. Compared with overweight white boys, overweight black boys have less visceral fat, more subcutaneous fat, and more thigh skeletal muscle.

Insulin resistance in children: consensus, perspective, and future directions

OBJECTIVE

Emerging data indicate that insulin resistance is common among children and adolescents and is related to cardiometabolic risk, therefore requiring consideration early in life. However, there is still confusion on how to define insulin resistance, how to measure it, what its risk factors are, and whether there are effective strategies to prevent and treat it. A consensus conference was organized in order to clarify these points.

PARTICIPANTS

The consensus was internationally supported by all the major scientific societies in pediatric endocrinology and 37 participants.

EVIDENCE

An independent and systematic search of the literature was conducted to identify key articles relating to insulin resistance in children.

CONSENSUS PROCESS

The conference was divided into five themes and working groups: background and definition; methods of measurement and screening; risk factors and consequences; prevention; and treatment. Each group selected key issues, searched the literature, and developed a draft document. During a 3-d meeting, these papers were debated and finalized by each group before presenting them to the full forum for further discussion and agreement.

CONCLUSIONS

Given the current childhood obesity epidemic, insulin resistance in children is an important issue confronting health care professionals. There are no clear criteria to define insulin resistance in children, and surrogate markers such as fasting insulin are poor measures of insulin sensitivity. Based on current screening criteria and methodology, there is no justification for screening children for insulin resistance. Lifestyle interventions including diet and exercise can improve insulin sensitivity, whereas drugs should be implemented only in selected cases.

Fasting and 2-hour plasma glucose and insulin: relationship with risk factors for cardiovascular disease in overweight nondiabetic children

OBJECTIVE

To determine whether elevated fasting or 2-h plasma glucose and/or insulin better reflects the presence of cardiovascular disease (CVD) risk markers in an overweight pediatric population with normal glucose tolerance.

RESEARCH DESIGN AND METHODS

A total of 151 overweight youths (8-17 years old) were evaluated with oral glucose tolerance tests and measurement of CVD risk factors. The study population was categorized according to quartiles of fasting and 2-h glucose and insulin levels. ANCOVA, adjusted for age, sex, race, Tanner stage, and percent body fat (measured by dual-energy X-ray absorptiometry), was used to compare metabolic variables between the quartiles of glucose and insulin groups.

RESULTS

Increasing quartiles of fasting and 2-h insulin were associated with increasing CVD risk factors. Glucose quartiles on the other hand, either fasting or at 2 h, were not.

CONCLUSIONS

These data suggest that hyperinsulinemia may be the earliest and/or primary metabolic alteration in childhood associated with risk markers for CVD. Prospective studies are needed.

Predicting cardiovascular risk in young adulthood from the metabolic syndrome, its component risk factors, and a cluster score in childhood

OBJECTIVE

The value of metabolic syndrome (MetS) in childhood and adolescence and its stability into young adulthood have been questioned. This study compared the MetS in late childhood (mean age 13) versus a cluster score of the MetS components as predictors of young adult (mean age 22) cardiovascular risk.

METHODS

Anthropometrics, blood pressure, lipid profile, and insulin resistance (insulin clamp) were obtained in 265 individuals at mean ages 13 and 22. The MetS was defined dichotomously by current pediatric and adult criteria. The MetS cluster score used the average of deviates of the MetS components standardized to their means and standard deviations at mean age 13.

RESULTS

The MetS was rarely present at mean age 13 and did not predict MetS at mean age 22 but identified individuals who continued to have adverse levels of risk factors at mean age 22. In contrast to the standard MetS definition, the MetS cluster score tracked strongly and at mean age 22 was significantly higher in the individuals with MetS at mean age 13 (0.78 ± 0.71) than those without MetS at mean age 13 (0.09 ± 0.70, p <0.0001).

CONCLUSIONS

Although the MetS at mean age 13, using the conventional definition, is not a reliable method for predicting the MetS at mean age 22, it does predict adverse levels of cardiovascular risk factors. A cluster score, using the MetS components as continuous variables, is more reliable in predicting young adult risk from late childhood.