Prediabetes in obese youth: a syndrome of impaired glucose tolerance, severe insulin resistance, and altered myocellular and abdominal fat partitioning

Newborn size, infant and childhood growth, and body composition and cardiovascular disease risk factors at the age of 6 years: the Pune Maternal Nutrition Study

OBJECTIVE

To study associations of size and body proportions at birth, and growth during infancy and childhood, to body composition and cardiovascular disease (CVD) risk factors at the age of 6 years.

DESIGN

The Pune Maternal Nutrition Study, a prospective population-based study of maternal nutrition and CVD risk in rural Indian children.

METHODS

Body composition and CVD risk factors measured in 698 children at 6 years were related to body proportions and growth from birth.

MEASUREMENTS

Anthropometry was performed every 6 months from birth. At 6 years, fat and lean mass (dual X-ray absorptiometry) and CVD risk factors (insulin resistance, blood pressure, glucose tolerance, plasma lipids) were measured.

RESULTS

Compared with international references (NCHS, WHO) the children were short, light and thin (mean weight <-1.0 s.d. at all ages). Larger size and faster growth in all body measurements from birth to 6 years predicted higher lean and fat mass at 6 years. Weight and height predicted lean mass more strongly than fat mass, mid-upper arm circumference (MUAC) predicted them both approximately equally and skinfolds predicted only fat mass. Neither birthweight nor the 'thin-fat' newborn phenotype, was related to CVD risk factors. Smaller MUAC at 6 months predicted higher insulin resistance (P<0.001) but larger MUAC at 1 year predicted higher systolic blood pressure (P<0.001). After infancy, higher weight, height, MUAC and skinfolds, and faster growth of all these parameters were associated with increased CVD risk factors.

CONCLUSIONS

Slower muscle growth in infancy may increase insulin resistance but reduce blood pressure. After infancy larger size and faster growth of all body measurements are associated with a more adverse childhood CVD risk factor profile. These rural Indian children are growing below international 'norms' for body size and studies are required in other populations to determine the generalizability of the findings.

Skeletal muscle subsarcolemmal mitochondrial dysfunction in high-fat fed rats exhibiting impaired glucose homeostasis

OBJECTIVE

To investigate whether changes in body energy balance induced by long-term high-fat feeding in adult rats could be associated with modifications in energetic behaviour and oxidative stress of skeletal muscle subsarcolemmal (SS) and intermyofibrillar (IMF) mitochondrial populations.

DESIGN

Adult rats were fed low-fat or high-fat diet for 7 weeks.

MEASUREMENTS

Body energy balance and composition analysis together with plasma insulin and glucose level determination in the whole animal. Oxidative capacity, basal and induced proton leaks as well as aconitase and superoxide dismutase activities in SS and IMF mitochondria from skeletal muscle.

RESULTS

High-fat fed rats exhibit increased body lipid content, as well as hyperinsulinemia, hyperglycaemia and higher plasma non-esterified fatty acids. In addition, SS mitochondria display lower respiratory capacity and a different behaviour of SS and IMF mitochondria is found in the prevention from oxidative damage.

CONCLUSIONS

A deleterious consequence of decreased oxidative capacity in SS mitochondria from rats fed high-fat diet would be a reduced utilization of energy substrates, especially fatty acids, which may lead to intracellular triglyceride accumulation, lipotoxicity and insulin resistance development. Our results thus reveal a possible role for SS mitochondria in the impairment of glucose homeostasis induced by high-fat diet.

Cardiovascular risk reduction in high-risk pediatric patients: a scientific statement from the American Heart Association Expert Panel on Population and Prevention Science; the Councils on Cardiovascular Disease in the Young, Epidemiology and Prevention, Nutrition, Physical Activity and Metabolism, High Blood Pressure Research, Cardiovascular Nursing, and the Kidney in Heart Disease; and the Interdisciplinary Working Group on Quality of Care and Outcomes Research

Although for most children the process of atherosclerosis is subclinical, dramatically accelerated atherosclerosis occurs in some pediatric disease states, with clinical coronary events occurring in childhood and very early adult life. As with most scientific statements about children and the future risk for cardiovascular disease, there are no randomized trials documenting the effects of risk reduction on hard clinical outcomes. A growing body of literature, however, identifies the importance of premature cardiovascular disease in the course of certain pediatric diagnoses and addresses the response to risk factor reduction. For this scientific statement, a panel of experts reviewed what is known about very premature cardiovascular disease in 8 high-risk pediatric diagnoses and, from the science base, developed practical recommendations for management of cardiovascular risk.

Lifestyle intervention in individuals with normal versus impaired glucose tolerance

BACKGROUND

Lifestyle intervention is effective in the prevention of type 2 diabetes in individuals with impaired glucose tolerance (IGT). It is currently unknown whether it has beneficial effects on metabolism to a similar extent, in individuals with normal glucose tolerance (NGT) compared to individuals with IGT.

MATERIALS AND METHODS

Data from 181 subjects (133 with NGT and at risk for type 2 diabetes and 48 with IGT) who participated in the Tuebingen Lifestyle Intervention Program with increase in physical activity and decrease in caloric intake were included into this study. Body fat distribution was quantified by whole-body magnetic resonance (MR) tomography and liver fat and intramyocellular fat by (1)H-MR spectroscopy. Insulin sensitivity was estimated from an oral glucose tolerance test (OGTT).

RESULTS

After 9 +/- 2 months of follow-up, the diagnosis of IGT was reversed in 24 out of 48 individuals. Only 14 out of 133 participants with NGT developed IGT. Body weight decreased in both groups by 3% (both P < 0.0001). Two-hour glucose concentrations during an OGTT decreased in individuals with IGT (-14%, P < 0.0001) but not with NGT (+2%, P = 0.66). Insulin sensitivity increased both in individuals with IGT (+9%, P = 0.04) and NGT (+17%, P < 0.0001). Visceral fat (-8%, P = 0.006), liver fat (-28%, P < 0.0001) and intramyocellular fat (-15%, P = 0.006) decreased in participants with IGT. In participants with NGT these changes were significant for visceral fat (-16%, P < 0.0001) and liver fat (-35%, P < 0.0001).

CONCLUSIONS

Moderate weight loss under a lifestyle intervention with reduction in total, visceral and ectopic fat and increase in insulin sensitivity improves glucose tolerance in individuals with IGT but not with NGT. In individuals with NGT, the beneficial effects of a lifestyle intervention on fat distribution and insulin sensitivity possibly prevent future deterioration in glucose tolerance.

Nonalcoholic fatty liver disease and insulin resistance in youth

Perspectives on the News commentaries are now part of a new, free monthly CME activity. The Mount Sinai School of Medicine, New York, New York, is designating this activity for 2.0 AMA PRA Category 1 credits. If you wish to participate, review this article and visit www.diabetes.procampus.net to complete a posttest and receive a certificate. The Mount Sinai School of Medicine is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide continuing medical education for physicians.

Hypertension in people with diabetes and the metabolic syndrome: pathophysiologic insights and therapeutic update

Hypertension (HTN) and type 2 diabetes mellitus (T2DM) are emerging as epidemics of the 21st century and are important components of the metabolic syndrome (MS). Evidence demonstrates a relationship between HTN, T2DM, and several vascular and metabolic abnormalities that are components of the MS. HTN affects nearly 70 million Americans and over one billion worldwide; likewise, the MS affects 44% of the US population above the age of 60 years and is rapidly increasing. HTN associated with the MS has certain pathophysiologic characteristics that provide clinical challenges. There is growing evidence that tissue activation of the renin-angiotensin system contributes to endothelial dysfunction, microalbuminuria, insulin resistance, and subsequent increased risk for cardiovascular and chronic kidney disease. The notion that HTN is a metabolic as well as a vascular disease provides a new treatment paradigm.

Healthy Lifestyle by Nutrition in Adolescence (HELENA). A New EU Funded Project

The key to health promotion and disease prevention in the 21st century is to establish an environment that supports positive health behaviour and healthy lifestyle from childhood. The HELENA project includes cross-sectional, crossover and pilot community intervention multi-centre studies, as an integrated approach to the above-mentioned problem. Dietary intake, nutrition knowledge and eating attitudes, food choices and preferences, body composition, biochemical, physical activity and fitness and genotype (to analyse gene-nutrient and gene-environment interactions) assessment will provide the full information about the nutritional and lifestyle status of the European adolescents. The requirements for health promoting foods will be also identified, and three sensory acceptable products for adolescents will be developed. Harmonization and standardisation of the assessments for both scientific and technological objectives should result in reliable and comparable data of a representative sample of European adolescents. This will contribute to understand why health-related messages are not being as effective as expected in the adolescent population. A realistic intervention strategy will be proposed in order to achieve the goals of understanding and effectively enhancing nutritional and lifestyle habits of adolescents in Europe.

Prise en charge ambulatoire de l'obésité: effets sur la composition corporelle et la capacité aérobie

AIMS

To assess the efficiency of an ambulatory weight management programme of pediatric obesity, including 1 gymnastic session per week, on body composition and physical fitness (max).

SUBJECTS

Fifteen adolescents participated in the 9-month intervention. BMI and fitness and physical activity assessed by a questionnaire were evaluated at baseline, and after intervention.

RESULTS

Prepubescent subjects (N=6): no significant change of BMI, body composition, nor max. Pubescent subjects: significant decrease of BMI, and z score BMI, and % fat mass, increase of fat free mass. Activity questionnaire: non-significant trend to decreased TV watching, significant increase in practice of physical activity during weekend.

CONCLUSION

A modest increase in physical practice, included in the dietary-behavioural management of adolescent obesity, is able to improve overweight and physical fitness.

Regional whole body fat quantification in mice

Obesity has risen to epidemic levels in the United States and around the world. Global indices of obesity such as the body mass index (BMI) have been known to be inaccurate predictors of risk of diabetes, and it is commonly recognized that the distribution of fat in the body is a key measure. In this work, we describe the early development of image analysis methods to quantify regional body fat distribution in groups of both male and female wildtype mice using magnetic resonance images. In particular, we present a new formulation which extends the expectation-maximization formalism commonly applied in brain segmentation to multi-exponential data and applies it to the problem of regional whole body fat quantification. Previous segmentation approaches for multispectral data typically perform the classification on fitted parameters, such as the density and the relaxation times. In contrast, our method directly computes a likelihood term from the raw data and hence explicitly accounts for errors in the fitting process, while still using the fitted parameters to model the variation in the appearance of each tissue class. Early validation results, using magnetic resonance spectroscopic imaging as a gold standard, are encouraging. We also present results demonstrating differences in fat distribution between male and female mice.

Cardiovascular risk factors in pre-pubertal Malays: effects of diabetic parentage

Diabetes prevalence is increasing rapidly in Asian populations but the influence of a family history of diabetes on cardiovascular risk is unknown. To assess this relationship, 120 urban-dwelling Malays were recruited to a cross-sectional case-control study. Sixty were pre-pubertal children, 30 of diabetic parentage (Group 1) and 30 with no diabetes family history (Group 2). Group 1 and 2 subjects were the offspring of adults with (Group 3) or without (Group 4) type 2 diabetes. Subjects were assessed for clinical and biochemical variables defining cardiovascular risk. Principal component analysis assessed clustering of variables in the children. Group 1 subjects had a higher mean waist:hip ratio, diastolic blood pressure and HbA(1c) than those in Group 2, and a lower HDL:total cholesterol ratio (P<0.03). Although there were no correlations between Group 1 and 3 subjects for cardiovascular risk variables, significant associations were found in Groups 2 and 4, especially HbA(1c) and insulin sensitivity (P< or =0.004). Of five separate clusters of variables (factors) identified amongst the children, the strongest comprised diabetic parentage, HbA(1c), insulin sensitivity and blood pressure. Features of the metabolic syndrome are becoming evident in the young non-obese children of diabetic Malays, suggesting that lifestyle factors merit particular attention in this group.

Development of insulin resistance and its relation to diet in the obese child

The incidence rate of obesity in youth has continued to increase worldwide and about 30% of obese children display insulin resistance (IR) and other metabolic abnormalities. The present study reviews the mechanisms for development of IR in the obese child and possible links between IR and dietary factors in childhood and adolescence. Although increased concentrations of plasma free fatty acids (FFA) and their counter part at intracellular level, long-chain acyl-coenzyme A (LC acyl-CoA), have been related to the early onset of IR in childhood obesity, a new endocrine paradigm states that adipose tissue secretes a wide variety of hormones and cytokines that regulate lipid energy metabolism. These hormonal changes precede any changes in metabolites such as FFA and glucose and appear to be associated with early IR in childhood. Excessive caloric intake increases IR in children; opposite, substantial reduction of overweight achieved by a hypocaloric diet decreases it. Elevated consumption of animal protein, particularly in early life, as well as diets rich in saturated, trans, and n-6 polyunsaturated fatty acids, and diets with a high carbohydrate to fat ratio, besides a high glycaemic and low-fiber diet also appear to exacerbate adiposity and IR.

Insulin sensitivity and mitochondrial function are improved in children with burn injury during a randomized controlled trial of fenofibrate

OBJECTIVE

To determine some of the mechanisms involved in insulin resistance immediately following burn trauma, and to determine the efficacy of PPAR-alpha agonism for alleviating insulin resistance in this population.

SUMMARY BACKGROUND DATA

Hyperglycemia following trauma, especially burns, is well documented. However, the underlying insulin resistance is not well understood, and there are limited treatment options.

METHODS

Twenty-one children 4 to 16 years of age with >40% total body surface area burns were enrolled in a double-blind, prospective, placebo-controlled randomized trial. Whole body and liver insulin sensitivity were assessed with a hyperinsulinemic-euglycemic clamp, and insulin signaling and mitochondrial function were measured in muscle biopsies taken before and after approximately 2 weeks of either placebo (PLA) or 5 mg/kg of PPAR-alpha agonist fenofibrate (FEN) treatment, within 3 weeks of injury.

RESULTS

The change in average daily glucose concentrations was significant between groups after treatment (146 +/- 9 vs. 161 +/- 9 mg/dL PLA and 158 +/- 7 vs. 145 +/- 4 FEN; pretreatment vs. posttreatment; P = 0.004). Insulin-stimulated glucose uptake increased significantly in FEN (4.3 +/- 0.6 vs. 4.5 +/- 0.7 PLA and 5.2 +/- 0.5 vs. 7.6 +/- 0.6 mg/kg per minute FEN; pretreatment vs. posttreatment; P = 0.003). Insulin trended to suppress hepatic glucose release following fenofibrate treatment (P = 0.06). Maximal mitochondrial ATP production from pyruvate increased significantly after fenofibrate (P = 0.001) and was accompanied by maintained levels of cytochrome C oxidase and citrate synthase activity levels. Tyrosine phosphorylation of the insulin receptor and insulin receptor substrate-1 in response to insulin increased significantly following fenofibrate treatment (P = 0.04 for both).

CONCLUSIONS

Fenofibrate treatment started within 1 week postburn and continued for 2 weeks significantly decreased plasma glucose concentrations by improving insulin sensitivity, insulin signaling, and mitochondrial glucose oxidation. Fenofibrate may be a potential new therapeutic option for treating insulin resistance following severe burn injury.

Visceral abdominal fat is correlated with whole-body fat and physical activity among 8-y-old children at risk of obesity

BACKGROUND

Abdominal fat is more related to health risk than is whole-body fat. Determining the factors related to children's visceral fat could result in interventions to improve child health.

OBJECTIVE

Given the effects of physical activity on adults' visceral fat, it was hypothesized that, after accounting for whole-body fat, physical activity would be inversely related to children's visceral (VAT), but not to subcutaneous (SAT), abdominal adipose tissue.

DESIGN

In this cross-sectional observational study conducted in forty-two 8-y-old children (21 boys, 21 girls) at risk of obesity [>75th body mass index (BMI) percentile, with at least one overweight parent], familial factors (eg, maternal BMI), historic weight-related factors (eg, birth weight), and the children's current physical activity (self-reported and measured with accelerometry) and diet were examined as potential correlates of the children's whole-body composition (measured with BMI and dual-energy X-ray absorptiometry) and abdominal fat distribution (measured by magnetic resonance imaging).

RESULTS

Accelerometer-measured physical activity was related to whole-body fat (r = -0.32, P < 0.10), SAT (r = -0.29, P < 0.10), and VAT (r = -0.43, P < 0.05). In regression models, whole-body fat was positively associated with and the only significant correlate of SAT. Whole-body fat was positively related and accelerometer-measured physical activity was negatively and independently related to the children's VAT.

CONCLUSIONS

Both SAT and VAT in 8-y-old children at risk of obesity are most closely associated with whole-body fat. However, after control for whole-body fat, greater physical activity is only associated with lower VAT, not SAT, in these children.

Cardiovascular Risk Reduction in High-Risk Pediatric Patients

Although for most children the process of atherosclerosis is subclinical, dramatically accelerated atherosclerosis occurs in some pediatric disease states, with clinical coronary events occurring in childhood and very early adult life. As with most scientific statements about children and the future risk for cardiovascular disease, there are no randomized trials documenting the effects of risk reduction on hard clinical outcomes. A growing body of literature, however, identifies the importance of premature cardiovascular disease in the course of certain pediatric diagnoses and addresses the response to risk factor reduction. For this scientific statement, a panel of experts reviewed what is known about very premature cardiovascular disease in 8 high-risk pediatric diagnoses and, from the science base, developed practical recommendations for management of cardiovascular risk.

Molecular mechanisms of insulin resistance in humans and their potential links with mitochondrial dysfunction

Recent studies using magnetic resonance spectroscopy have shown that decreased insulin-stimulated muscle glycogen synthesis due to a defect in insulin-stimulated glucose transport activity is a major factor in the pathogenesis of type 2 diabetes. The molecular mechanism underlying defective insulin-stimulated glucose transport activity can be attributed to increases in intramyocellular lipid metabolites such as fatty acyl CoAs and diacylglycerol, which in turn activate a serine/threonine kinase cascade, thus leading to defects in insulin signaling through Ser/Thr phosphorylation of insulin receptor substrate (IRS)-1. A similar mechanism is also observed in hepatic insulin resistance associated with nonalcoholic fatty liver, which is a common feature of type 2 diabetes, where increases in hepatocellular diacylglycerol content activate protein kinase C-epsilon, leading to reduced insulin-stimulated tyrosine phosphorylation of IRS-2. More recently, magnetic resonance spectroscopy studies in healthy lean elderly subjects and healthy lean insulin-resistant offspring of parents with type 2 diabetes have demonstrated that reduced mitochondrial function may predispose these individuals to intramyocellular lipid accumulation and insulin resistance. Further analysis has found that the reduction in mitochondrial function in the insulin-resistant offspring can be mostly attributed to reductions in mitochondrial density. By elucidating the cellular and molecular mechanisms responsible for insulin resistance, these studies provide potential new targets for the treatment and prevention of type 2 diabetes.

Paediatric metabolic syndrome and associated anthropometric indices: the CASPIAN Study

AIM

To determine the prevalence of paediatric metabolic syndrome (MetS) and its best predictive anthropometric index.

METHODS

This national study was conducted among 4811 students (2248 boys and 2563 girls) aged 6-18 y. This is the first study of its kind in Iran and, to our knowledge, in Asia as well. Two definitions were used for the MetS: type A was defined based on criteria analogous to ATP III, and type B was defined according to the cut-offs obtained from NHANES III. Both types A and B define high fasting blood sugar as > 100 mg/dl and systolic/diastolic blood pressure as > 90th percentile.

RESULTS

The mean (SD) age of students studied was 12.07+/-3.2 y. MetS type A was seven times more prevalent than type B (14% vs 2%, respectively, p<0.0001), and had no significant gender difference. The most frequent components of both definitions of the MetS were low high-density lipoprotein cholesterol (HDL-C) and high triglyceride (TG). Waist circumference (WC) and waist-to-hip ratio (WHR) had the strongest and weakest associations, respectively, with the MetS.

CONCLUSION

Establishment of a uniform set of criteria for the MetS in children is needed. Routine WC measurement in the paediatric population may be clinically useful.

Ventilation and Its Control during Incremental Exercise in Obesity

BACKGROUND

In obesity, the addition of mass loading of the chest wall by adipose tissue decreases compliance, but its ventilation does not seem to be a limiting factor to physical performance. Plasma K(+) and lactic acid are considered important determinants of ventilation during exercise. Obesity is characterized by insulin resistance.

OBJECTIVES

The aim of this study was to assess ventilatory adaptations to sustained effort and the effects of lactic acid and potassium in young obese subjects.

METHODS

Twelve obese subjects with a body mass index of 40 (mean age 27 years, 6 males) and 12 normal subjects with a body mass index of 22 (aged 28 years, 6 males) performed a progressive cycloergometric test with increases of 20 W every 4 min to exhaustion while minute ventilation, oxygen consumption, carbon dioxide production, end-tidal oxygen pressure, and end-tidal carbon dioxide pressure were measured. Blood samples were collected at the end of every step to determine plasma K(+). Lactic acid was measured at rest, 40, 80, 120 W and peak exercise (or only at peak exercise if <120 W). Before each exercise, we tested insulin sensitivity using the quantitative insulin sensitivity check index.

RESULTS

Obese subjects had lower insulin sensitivity (0.318 vs. 0.345, p < 0.01). Peak exercise was not significantly different between both groups (125 W in the obese group vs. 137 W in the control group), but the ventilatory threshold was at lower power output in the obese group compared to the controls (76 vs. 107 W, p < 0.05). Ventilation increased less in the obese group but oxygen saturation of hemoglobin remained within normal limits up to exhaustion in both groups. Ventilation was appropriate for the CO(2) increase but less appropriate for the increased O(2) consumption. Both K(+) and lactic acid increased less in the obese group.

CONCLUSIONS

In our obese subjects, ventilation was not a limiting factor during exercise. Its lower increase may be due, in addition to the characteristics of their chest walls, to insulin resistance which may limit the increase in lactic acid during effort, and to the hypertrophy of muscle fibers previously noted, which may be linked to a lower increase in plasma K(+) during physical exercise.

Adiponectin in childhood and adolescent obesity and its association with inflammatory markers and components of the metabolic syndrome

CONTEXT

Adiponectin levels are lower in obese children and adolescents, whereas markers of inflammation and proinflammatory cytokines are higher. Hypoadiponectinemia may contribute to the low-grade systemic chronic inflammatory state associated with childhood obesity.

OBJECTIVE

We investigated whether C-reactive protein (CRP), the prototype of inflammation, is related to adiponectin levels independently of insulin resistance and adiposity.

DESIGN, SETTING, PARTICIPANTS, AND MAIN OUTCOME MEASURES

In a multiethnic cohort of 589 obese children and adolescents, we administered a standard oral glucose tolerance test and obtained baseline measurements for adiponectin, plasma lipid profile, CRP, IL-6, and leptin.

RESULTS

Stratifying the cohort into quartiles of adiponectin levels and adjusting for potential confounding variables, such as age, gender, ethnicity, body mass index z-score, pubertal status, and insulin sensitivity, the present study revealed that low levels of adiponectin are associated not only with higher CRP levels, but also with components of the metabolic syndrome, such as low high-density lipoprotein cholesterol and a high triglyceride-to-high-density-lipoprotein ratio.

CONCLUSIONS

The link between adiponectin levels and a strong marker of inflammation, CRP, is independent of insulin resistance and adiposity in obese children and adolescents. Adiponectin may be one of the signals linking inflammation and obesity. Thus, adiponectin may function as a biomarker of the metabolic syndrome in childhood obesity.

[Effects of puberty on glucose-lipid balance during exercise in the obese child]

The aim of the present study was to investigate effect of puberty on substrate oxidation rates using a graded exercise test to exhaustion. Two groups of obese adolescent males (34 prepubertal: body mass index (BMI) = 25,94 +/- 2,63; Z-score = 4,43 +/- 1,83; and 26 postpubertal: BMI = 31,14 +/- 4,88; Z-score = 5,264 +/- 1,76) performed an exercise test on a cycle ergometer. The test consisted in a series of graded exercises on a cycle ergometer. Stage duration was 3 min 30 s. Fat and carbohydrate rates were calculated during the last 30 s of each stage using stoichiometric equations, and this permitted us to calculate substrate oxidation according to exercise intensity. Lipid oxidation rates are significantly higher in the postpubertal group. When the fat oxidation rates are reported relative to fat free mass, fat oxidation rates are higher in the prepubertal group. Puberty decreases significantly the capacity of fat free mass to oxidize fat for a same level of exercise.

Cardiorespiratory fitness and abdominal adiposity in youth

The purpose of this study was to determine whether cardiorespiratory fitness (CRF) is associated with lower abdominal adiposity in youth. Subjects included healthy 61 African-American and 52 white children and adolescents (age: 8-17 years). Body composition was measured by dual-energy X-ray absorptiometry and computed tomography. CRF (VO(2max)) was assessed using a graded maximal treadmill test. CRF was inversely related (P<0.05) to total adiposity, waist circumference, and visceral and abdominal subcutaneous adipose tissue (AT) independent of race. These findings remained significant (P<0.05) after adjusting for age, gender and pubertal status. Multiple regression analyses revealed that CRF is an independent contributor (P<0.05) of waist circumference, and visceral and abdominal subcutaneous AT after accounting for age, pubertal status, gender and body mass index percentile. Our observation suggest that in youth, CRF is associated with lower visceral and abdominal subcutaneous AT, and reinforces the notion that youth should engage in regular physical activity to improve aerobic fitness and reduce abdominal adiposity.

Insulin resistance and whole body energy homeostasis in obese adolescents with fatty liver disease

Obese adolescents are at risk of developing NAFLD and type 2 diabetes. We measured noninvasively the IHF content of obese adolescents to ascertain whether it is associated with insulin resistance and abnormal energy homeostasis. IHF content, whole body energy homeostasis, insulin sensitivity, and body composition were measured using localized hepatic (1)H-MRS, indirect calorimetry, fasting-derived and 3-h-OGTT-derived surrogate indexes (HOMA2 and WBISI), and DEXA, respectively, in 54 obese adolescents (24 female and 30 male, age 13 +/- 2 yr, BMI >99th percentile for their age and sex). NAFLD (defined as IHF content >5% wet weight) was found in 16 individuals (30%) in association with higher ALT (P < 0.006), Hb A(1c) (P = 0.021), trunk fat content (P < 0.03), and lower HDL cholesterol (P < 0.05). Individuals with NAFLD had higher fasting plasma glucose (89 +/- 8 vs. 83 +/- 9 mg/dl, P = 0.01) and impaired insulin sensitivity (HOMA2 and WBISI, P < 0.05). Meanwhile, parameters of insulin secretion were unaffected. Their reliance on fat oxidation in the fasting state was lower (RQ 0.83 +/- 0.08 vs. 0.77 +/- 0.05, P < 0.01), and their ability to suppress it during the oral glucose challenge was impaired (P < 0.05) vs. those with normal IHF content. When controlling for trunk fat content, the correlation between IHF content and insulin sensitivity was weakened, whereas the correlation with fasting lipid oxidation was maintained. In conclusion, NAFLD is common in childhood obesity, and insulin resistance is present in association with increased trunk fat content. In contrast, the rearrangement of whole body substrate oxidation in these youngsters appeared to be an independent feature.

Waist circumference and body mass index in Chinese children: cutoff values for predicting cardiovascular risk factors

BACKGROUND

Body mass index (BMI) and waist circumference (WC) correlate with cardiovascular (CV) risk factors in childhood which track into adulthood. WC provides a measure of central obesity, which has been specifically associated with CV risk factors. Reference standards for WC, and for WC and BMI risk threshold values are not established in Chinese children.

OBJECTIVES

To construct reference percentile charts of WC, establish relationships between WC, BMI and other risk factors, and propose WC and BMI threshold values predictive of CV risk factors in Hong Kong ethnic Chinese children.

METHODS

Weight, height, waist and hip circumference were measured in 2593 (52% boys, 47% girls) randomly sampled Hong Kong school children aged 6-12 years. In 958 of these and 97 additional overweight children (n=1055), the relationships between WC, BMI, waist/hip and waist/height ratio and six age-adjusted CV risk factors (>85% percentile levels of blood pressure (BP), fasting triglycerides, low-density lipoprotein (LDL) cholesterol, glucose and insulin levels, and <15% percentile levels of high-density lipoprotein (HDL) cholesterol) were studied. Receiver-operating characteristic analysis was employed to derive optimal age-adjusted sex-specific WC and BMI thresholds for predicting these measures of risk.

RESULTS

WC percentiles were constructed. WC correlated slightly more than BMI with CV risk factors and most strongly with insulin and systolic BP, but poorly or not with LDL and glucose. Optimal WC and BMI risk thresholds for predicting four of these six CV risk factors were ca. the 85th percentiles (sensitivities approximately 0.8, specificities approximately 0.87) with age-specific cutoff values in girls/boys from approximately 57/58 to approximately 71/76 cm and 17/18 to 22/23 kg/m(2).

CONCLUSION

These are the first set of WC reference data for Chinese children. WC risk cutoff values are proposed which, despite a smaller waist in Chinese children, are similar to those reported for American children. WC percentiles may reflect population risk.

Muscle triglycerides and mitochondrial function: possible mechanisms for the development of type 2 diabetes

INTRODUCTION

Obese and type 2 diabetic (T2DM) adolescents present with reduced insulin-stimulated glucose disposal and elevated intramyocellular lipids (IMCL) indicating comparable muscular insulin resistance and increased flux of free fatty acids (FFA) as in adult patients. In humans, the causal relationships between obesity and insulin resistance were examined in detail over the last years.

METHODS

The impact of genetic factors was analyzed in young nonobese nondiabetic first-degree relatives of T2DM (REL-DM), whereas environmental factors were tested by challenging humans without genetic T2DM risk with lipid infusions or high-fat diets.

RESULTS

REL-DM exhibit defects in mitochondrial oxidation and phosphorylation. Increased FFA availability results in accumulation of intramyocellular fatty acyl-CoA (FA-CoA) inducing a series of alterations: (i) inhibition of insulin signaling, (ii) reduction of insulin-(in)dependent glucose transport/phosphorylation, (iii) decreased insulin-stimulated glycogen synthesis, (iv) impaired insulin-stimulated oxidative phosphorylation (ATP synthesis), (v) accumulation of ectopic triglycerides (IMCL), (vi) reduced expression of peroxisome proliferator activated receptor gamma (PPARgamma) coactivator-1 (PGC-1) and PGC-1-controlled genes involved in mitochondrial biogenesis and oxidative phosphorylation and possibly also (vii) initiation of inflammatory processes by activation of PKC and nuclear factor-kappaB and decreased expression of matrix metalloproteinases (MMPs).

CONCLUSIONS

The abnormalities could lead to a vicious cycle in which mitochondrial dysfunction, elevation of intramycellular lipids, impaired lipid oxidation and insulin resistance amplify each other. This is similar to the adaptive changes to fasting, which prevent energy loss during excessive FFA availability. The sequence of events may start with mitochondrial dysfunction in genetic insulin resistance and with increased intramyocellular lipids in environmental insulin resistance.

Association of anthropometric indices with cardiovascular disease risk factors among children and adolescents: CASPIAN Study

BACKGROUND

For the first time in Iran, and to the best of our knowledge in Asia, we assessed the anthropometric indices most closely correlated to cardiovascular disease (CVD) risk factors in a large nationally representative sample of children and adolescents to be used as a simple tool for identifying those at risk.

METHODS

This multi-center study was performed among a representative sample of 4811 school students (2248 boys and 2563 girls) aged 6-18 years, as part of the baseline survey of a national surveillance system. Anthropometric indices and CVD risk factors were measured using standard protocols, and their correlation was analyzed by using Receiver Operator Characteristic (ROC) curves and partial correlation.

RESULTS

The most prevalent CVD risk factors were low HDL-C (28%), followed by hypertriglyceridemia (20.1%), and overweight (17%). The ROC analyses showed that among boys, all anthropometric indices had the same association with CVD risk factors in 6-9.9-year-age group, while in the 10-13.9 and 14-18-year-age groups, respectively waist circumference (WC) and body mass index (BMI) were the best in distinguishing CVD risk factors. Among girls, these indices were respectively BMI and waist to stature ratio (WSR); WC and WSR; and WC. In the partial correlation analysis, in boys, the highest coefficient was found for BMI; BMI and WC; and for WC and WSR; in girls, these indices were BMI; WC and WSR; and BMI respectively.

CONCLUSIONS

In the present study, BMI, WC and WSR were the most appropriate in predicting CVD risk factors. It may be clinically useful in the pediatric population to routinely measure WC and WSR in addition to BMI as a screening tool to identify high-risk youth.

Effect of a short-term diet and exercise intervention on metabolic syndrome in overweight children

Overweight and the metabolic syndrome are increasing radically in children. The present study was designed to examine the effects of lifestyle modification in 16 children who were placed on a high-fiber, low-fat diet in a 2-week residential program where food was provided ad libitum and daily aerobic exercise was performed. In each subject, pre- and postintervention fasting blood was drawn. Insulin (27.2 +/- 3.5 vs 18.3 +/- 1.7 microU/mL, P < .01), homeostasis model assessment for insulin resistance (5.79 +/- 0.81 vs 4.13 +/- 0.38, P < .05), and body weight (92.0 +/- 7.0 vs 88.0 +/- 6.8 kg, P < .01) were reduced significantly. Total cholesterol (165 +/- 7.8 vs 127 +/- 7.4 mg/dL, P < .01), low-density lipoprotein (94.1 +/- 8.2 vs 68.5 +/- 6.7 mg/dL, P < .01), triglycerides (146 +/- 16.2 vs 88.1 +/- 8.1 mg/dL, P < .01), and total cholesterol-high-density lipoprotein (4.16 +/- 0.30 vs 3.34 +/- 0.30, P < .01) and low-density lipoprotein-high-density lipoprotein ratios (2.41 +/- 0.3 vs 1.86 +/- 0.2, P < .01) were reduced, with no change in high-density lipoprotein observed (42.3 +/- 2.4 vs 40.8 +/- 3.0 mg/dL). Systolic blood pressure (130 +/- 3.1 vs 117 +/- 1.8 mm Hg, P < .001) and diastolic blood pressure (74.3 +/- 3.0 vs 67.2 +/- 2.3 mm Hg, P = .01) also decreased. Most notably, before the intervention, 7 of the 16 subjects were classified with metabolic syndrome. After the 2-week intervention, despite remaining overweight, reversal of metabolic syndrome was noted in all 7 subjects. All of these changes occurred despite only modest improvements in the percentage of body fat (37.5% +/- 1.1% vs 36.4% +/- 1.2%, P < .01) and body mass index (33.2 +/- 1.9 vs 31.8 +/- 1.9 kg/m(2), P < .01). These results indicate that a short-term rigorous diet and exercise regimen can reverse metabolic syndrome, even in youth without documented atherosclerosis.

Risk of progression to type 2 diabetes based on relationship between postload plasma glucose and fasting plasma glucose

OBJECTIVE

We sought to assess the risk of progression to type 2 diabetes in normal glucose tolerance (NGT) subjects based on the relationship between the plasma glucose concentration during oral glucose tolerance tests (OGTTs) and the fasting plasma glucose (FPG) concentration.

RESEARCH DESIGN AND METHODS

Subjects with NGT (n = 1,282) from the San Antonio Heart Study received an OGTT with measurement of the plasma glucose concentration at 0, 30, 60, and 120 min at baseline and after 7-8 years of follow-up. Subjects were divided into four groups based on the relationship between the plasma glucose concentration during the OGTT and the FPG concentration on the same day as the OGTT. Insulin resistance was calculated by the homeostasis model assessment of insulin resistance (HOMA-IR) and Matsuda index. Early-phase insulin secretion was calculated as the ratio between the incremental plasma insulin and glucose concentrations during the first 30 min of the OGTT (DeltaI(0-30)/DeltaG(0-30)). Total insulin secretion was calculated as the ratio between the incremental areas under the insulin and glucose curves during the OGTT [DeltaG(AUC)/DeltaI(AUC)].

RESULTS

In 23 subjects (group I), the plasma glucose concentration during the OGTT returned to levels below the FPG concentration at 30 min; in 111 subjects (group II) and in 313 subjects (group III), the plasma glucose concentration during the OGTT returned to levels below the FPG concentration at 60 and 120 min, respectively. In the remaining 835 subjects (group IV), the plasma glucose concentration during the OGTT never fell below the FPG concentration. Insulin resistance, measured by HOMA-IR and the Matsuda index, increased progressively from group I through group IV, while insulin secretion measured by DeltaI(0-30)/DeltaG(0-30) and DeltaG(AUC)/DeltaI(AUC) decreased progressively from group I through group IV. The incidence of type 2 diabetes was 0% in group I and progressively increased to 0.9% in group II, 3.2% in group III, and 6.4% in group IV.

CONCLUSIONS

Subjects whose postload plasma glucose concentration returned to baseline (i.e., FPG level) more quickly had greater insulin sensitivity, a higher insulinogenic index, and a lower risk of developing type 2 diabetes after 8 years of follow-up compared with subjects whose postload glucose concentration returned to baseline more slowly.

Development of type 2 diabetes in children and adolescents

Type 2 diabetes is emerging as a significant health problem in children and adolescents. The disease usually develops in obese insulin-resistant youth with a typical pattern of lipid partitioning characterized by increased lipid deposition in myocytes, the visceral compartment, and the liver. Unfavorable adipocytokine profiles, together with a state of low-grade inflammation, create an additional metabolic burden tightly coupled to other components of the metabolic syndrome. Insufficient beta-cell compensation promotes altered glucose metabolism.

Prevalence of risk for type 2 diabetes in school children

According to the Centers for Disease Control and Prevention, 1 in 3 children born in 2000 in the United States will become diabetic. The odds are higher for African American and Hispanic children as nearly 50% of them will develop diabetes. Random screening is not effective in identifying children at risk for type 2 diabetes mellitus (T2DM); therefore, there is a need to apply screening strategies that guide the development of appropriate primary prevention efforts. To assess the prevalence of risk factors for T2DM, 1066 fifth-grade children were screened using American Diabetes Association guidelines. Overall, 22.6% were found at risk; African American and Hispanic children were almost 8 times more likely to be at risk when compared to Caucasians (odds ratio = 7.41 and 7.87). Children who reported watching TV/playing video games 2 or more hours/day were 73% more likely to be at risk. Children identified to be at risk were referred to their primary care provider and were invited to participate in a counseling session. The environmental risk factors for T2DM identified in this study are modifiable and should be targeted in preventive interventions at the school and community level to reduce overweight and consequently prevent T2DM in children, especially among minority children.

Childhood obesity: a growing public health concern

Childhood obesity has been deemed epidemic, a term usually reserved for infectious diseases that sweep populations. This review begins with guidance regarding obesity definitions and a review of the data on global prevalence. The next section details the myriad health consequences for immediate and long-term physical and psychosocial health outcomes. The authors then discuss what is known regarding distal and proximal causes and correlates at the individual and contextual levels of family, health care, schools and community. The final sections provide a summary of interventions in diverse settings and some current thinking on how the field is likely to evolve over the next several years.

Ethnic differences in beta cell adaptation to insulin resistance in obese children and adolescents

AIMS/HYPOTHESIS

The prevalence of altered glucose metabolism in obese children and adolescents is growing at a significant rate, especially in ethnic minorities. It is not clear whether young people of different ethnic backgrounds differ in their adaptive mechanisms to obesity-related insulin resistance. The aim of this study was to evaluate the early insulin response and insulin clearance in response to an oral glucose load in obese children and adolescents.

METHODS

Seven hundred and nine obese children and adolescents underwent an OGTT. Indices of the early insulin response and insulin clearance were compared in participants of White European, African American and Hispanic origin.

RESULTS

Participants of the three ethnic groups demonstrated similar mechanisms of adaptation to increasing insulin resistance, but with different magnitudes. African American subjects had a greater early insulin response and decreased insulin clearance than their White European and Hispanic counterparts. This happened regardless of whether the cohort was divided by glucose tolerance level or by level of insulin sensitivity. IGT across ethnic groups was characterised by a marked decline in the acute insulin response in the context of severe insulin resistance and very low insulin clearance.

CONCLUSIONS/INTERPRETATION

In obese children and adolescents, mechanisms of adaptation to obesity related to insulin resistance are similar across ethnic groups. The greater early insulin response needed to maintain glucose tolerance in young people of ethnic minorities may partially explain their greater tendency to develop type 2 diabetes.

Waist circumference is an independent predictor of insulin resistance in black and white youths

OBJECTIVES

We examined how well waist circumference (WC) reflects total and abdominal fat and whether WC predicts insulin resistance independent of body mass index (BMI) percentile in youths.

STUDY DESIGN

Body composition was measured by dual-energy x-ray absorptiometry and abdominal adiposity by computed tomography. Insulin sensitivity was measured by the hyperinsulinemic-euglycemic clamp.

RESULTS

Both BMI percentile and WC were significantly associated (P < .01) with total and abdominal fat and insulin sensitivity. WC remained a significant (P < .01) correlate of total and abdominal fat and insulin sensitivity after controlling for BMI percentile. By contrast, BMI percentile did not remain a significant correlate of visceral fat and markers of insulin resistance after controlling for WC. Without exception, WC explained a greater variance in abdominal fat and metabolic profiles than did BMI percentile.

CONCLUSIONS

Our findings suggest that the prediction of health risks associated with obesity in youths is improved by the additional inclusion of WC measure to the BMI percentile. Such observations would reinforce the importance of including WC in the assessment of childhood obesity to identify those at increased metabolic risk due to excess abdominal fat.

Characterisation of morbidity in a UK, hospital based, obesity clinic

AIM

To identify clinical features which predict those most at risk of co-morbidities within an obesity clinic.

METHODS

Children attending an obesity clinic had fasting glucose, insulin, and lipids measured prior to a standard oral glucose tolerance test (OGTT). History and examination established birth weight, family history of type 2 diabetes/obesity, pubertal status, and presence of acanthosis nigricans. Central and total fat mass was estimated by bio-impedance.

RESULTS

Of the 126 children evaluated, 10.3% (n = 13) had impaired glucose tolerance (IGT); the majority (n = 11) of these would not have been identified on fasting glucose alone. Those with IGT were more likely to have a parental history of type 2 diabetes (relative risk 3.5). IGT was not associated with acanthosis nigricans. Twenty five per cent (n = 19) of those evaluated (n = 75) had evidence of the "metabolic syndrome" (MS). HDL cholesterol and triglyceride levels were related to insulin sensitivity (HOMA-R); HDL cholesterol was also related to birth weight SDS. We observed a trend for those with MS to have a lower birth weight SDS. The severity of obesity did not influence the likelihood of IGT or MS.

CONCLUSIONS

Significant numbers of obese children have associated co-morbidities. Analysis of fasting blood glucose samples alone is not satisfactory to adequately evaluate glucose homoeostasis. The overall level of obesity does not predict co-morbidities. Special attention should be given to those with parental diabetes and a history of low birth weight who are more likely to have IGT and abnormal lipid profiles respectively.

New imaging techniques of fat, muscle and liver within the context of determining insulin sensitivity

Body fat distribution and ectopic fat deposition are important determinants of insulin sensitivity. Fat deposition in muscle and the liver, in particular, has been found to impair insulin signalling in these insulin-sensitive tissues. Thus, exact quantification of fat content may help to distinguish between different sites of insulin resistance. Increased fat deposition in the visceral compartment compared with the subcutaneous depot also represents an important factor leading to insulin resistance. Recent data clearly showed that visceral fat is a strong determinant of liver fat content. Exact quantification of fat distribution by magnetic resonance imaging and magnetic resonance spectroscopy may help to define distinct 'fat-distribution phenotypes'. This may allow a search for new candidate genes for type 2 diabetes mellitus and identify, at an early stage, individuals at risk for decline in insulin sensitivity.

Childhood obesity and the metabolic syndrome

The current epidemic of obesity reflects environmental changes that have an impact on a genetically susceptible population. The scope of obesity and its associated comorbidities warrants its position among the most crucial global public health problems faced today. Society has gained better appreciation for the significance of this problem yet still has much to learn regarding how best to address the obesity crisis. Although strategies for treating individuals who have weight problems successfully continue to evolve, the most profound impacts ultimately will arise from societal changes dictating that all individuals strive to adopt a healthy lifestyle.

Type 2 diabetes mellitus in youth: the complete picture to date

Type 2 diabetes mellitus is a heterogeneous condition in which the clinical manifestation of hyperglycemia is a reflection of the impaired balance between insulin sensitivity and insulin secretion. Clinical experience and research in youth type 2 diabetes mellitus are in an early stage because of the relative novelty of the condition in pediatrics. This article discusses the amassed information in type 2 diabetes mellitus of youth to date with respect to the epidemiology, pathophysiology, risk factors, clinical presentation, screening, and management strategies.

Pediatric obesity phenotyping by magnetic resonance methods

PURPOSE OF REVIEW

Accurate measurement of adiposity in obese children is required for characterizing the condition's phenotype, severity, and treatment effects in vivo. Non-invasive and safe, magnetic resonance imaging and spectroscopy provide an important new approach for characterizing key aspects of pediatric obesity. This review focuses on recent advances in non-invasive magnetic resonance imaging and spectroscopy for quantifying total body and regional adiposity, mapping adipose tissue distribution, and evaluating selected metabolic disturbances in children. The aim is to provide an investigator-focused overview of magnetic resonance methods for use in the study of pediatric body composition and metabolism.

RECENT FINDINGS

Whole body axial images can be rapidly acquired on most clinical magnetic resonance imaging scanners. The images can then be semi-automatically segmented into subcutaneous, visceral, and intramuscular adipose tissue. Specific pediatric studies of errors related to slice gap and number are available. The acquisition of scans in healthy and premature infants is now feasible with recent technological advances. Spectroscopic, Dixon, and other approaches can be used to quantify the lipid content of liver, skeletal muscle, and other organs. Protocol selection is based on factors such as subject age and cost. Particular attention should be directed towards identification of landmarks in growth studies. Recent advances promise to reduce the requirement of subjects to remain motionless for relatively long periods.

SUMMARY

Magnetic resonance imaging and spectroscopy are safe, practical, and widely available methods for phenotyping adiposity in children that open new opportunities for metabolism and nutritional research.

Polymorphisms in the gene encoding adiponectin receptor 1 are associated with insulin resistance and high liver fat

AIMS/HYPOTHESIS

The adipokine adiponectin has insulin-sensitising, anti-atherogenic and anti-inflammatory properties. Recently, the genes for mouse and human adiponectin receptor-1 (ADIPOR1) and -2 (ADIPOR2) have been cloned. The aim of this study was to investigate whether genetic variants of the genes encoding ADIPOR1 and ADIPOR2 play a role in human metabolism.

MATERIALS AND METHODS

We screened ADIPOR1 and ADIPOR2 for polymorphisms and determined their association with glucose metabolism, lipid metabolism, an atherogenic lipid profile and inflammatory markers in 502 non-diabetic subjects. A subgroup participated in a longitudinal study; these subjects received diet counselling and increased their physical activity.

RESULTS

We identified six variants of ADIPOR1 and seven variants of ADIPOR2. A single-nucleotide polymorphism (SNP) in the putative promoter region 8503 bp upstream of the translational start codon (-8503 G/A) of ADIPOR1 (frequency of allele A=0.31) was in almost complete linkage disequilibrium with another SNP (-1927 T/C) in intron 1. Subjects carrying the -8503 A and -1927 C alleles had lower insulin sensitivity, as estimated from a 75 g OGTT (p=0.04) and determined during a euglycaemic clamp (n=295, p=0.04); they also had higher HbA(1)c levels (p=0.02) and, although the difference was not statistically significant, higher liver fat (n=85, determined by proton magnetic resonance spectroscopy, p=0.056) (all p values are adjusted for age, sex and percentage of body fat). In the longitudinal study (n=45), the -8503 A and -1927 C alleles were associated with lower insulin sensitivity (p=0.03) and higher liver fat (p=0.02) at follow-up compared with the -8503 G and -1927 T alleles, independently of basal measurements, sex and baseline and follow-up percentage of body fat.

CONCLUSIONS/INTERPRETATION

The present findings suggest that the -8503 G/A SNP in the promoter or the -1927 T/C SNP in intron 1 of ADIPOR1 may affect insulin sensitivity and liver fat in humans.

Intolerancia a la glucosa en niños y adolescentes obesos

BACKGROUND AND OBJECTIVE

The rise in the prevalence of glucose intolerance and type 2 diabetes mellitus in childhood and adolescence in recent decades appears to be closely related to the increase in the incidence of obesity in developed countries. We decided to establish the frequency of glucose intolerance and type 2 diabetes mellitus in a population of obese children and adolescents evaluated at our hospital.

PATIENTS AND METHOD

Prospective study of 145 obese patients (60 boys: BMI 29.5 (4.9), BMI z score 4.4 (1.7); and 85 girls: BMI 28.8 (4.6), BMI z score 3.8 (1.4); age range: (4-18 years) who underwent an oral glucose tolerance test (OGTT) between 1998 and 2003. OGTT results were evaluated according to WHO criteria. Insulin secretion and sensitivity parameters (HOMA, QUICKI, area under the curve for glycemia, area under the curve for insulin and insulinogenic index) were also calculated.

RESULTS

The frequency of glucose intolerance in the whole population was 19.2%. However, this prevalence varied with age and maturation stage (prepuberty 7.0%, puberty 28.2% and postpuberty 26.5%), and with the obesity degree (BMI z-score between +2 and +3: 8.9%; between +3 and +4: 21.9% and higher than +4: 25%). No type 2 diabetes mellitus cases were observed.

CONCLUSIONS

Obese children and adolescents display an elevated incidence of glucose intolerance which seems to be related to the degree of adiposity.

The metabolic consequences of childhood obesity

The prevalence of childhood obesity is increasing worldwide, as is the prevalence of obesity-related co-morbidity. Altered glucose metabolism, manifested as impaired glucose tolerance (IGT), appears early in obese children and adolescents. Obese young people with IGT are characterized by marked peripheral insulin resistance and a relative beta-cell failure. Lipid deposition in muscle and the visceral compartment, and not only adiposity per se, is related to increased peripheral insulin resistance, the "driving force" of the metabolic syndrome. Other elements of the metabolic syndrome, such as dyslipidemia and hypertension, are already present in obese youngsters and worsen with the degree of obesity. Similarly, markers of systemic "low-grade inflammation" worsen with increasing adiposity. The long-term impact on cardiovascular and liver morbidity of obesity-related insulin resistance in young people is expected to emerge as these youngsters become young adults.

Nutritional Management of the overweight child with type 2 diabetes

In light of the strong association between excess weight and type 2 diabetes, the nutritional management of the child with type 2 diabetes often focuses on changing dietary and physical activity habits to normalize weight, instill long-term healthy habits, and provide glycemic control. A multidisciplinary approach to the treatment of childhood obesity should include the child's family and caregivers to be most effective. Weight goals in children should be based on the age of the child, the extent of overweight, and the presence of complications. Likewise, physical activity is an important component of treatment and should be titrated to the child's age, ability and overweight status. Efforts to avoid the development of obesity, and potentially type 2 diabetes, should be started early in the child's life. Education and fostering a healthy lifestyle during childhood is the best defense to slow down or reverse the obesity epidemic in our society that is now affecting even the youngest of children, setting them up for potentially life-threatening diseases in the future.

Hormonal and metabolic consequences of childhood obesity

It is apparent that chronic illnesses such as type 2 diabetes and cardiovascular disease originate in childhood. Obesity in childhood and adolescence hastens their development, enhances their rates of progression, increases the risks of severe complications, and if persistent, reduces life expectancy.