Both moderate to high levels of cardiorespiratory fitness and sedentary activities, but not physical activity, are associated with lower abdominal adiposity, as measured by waist circumference.

The aim of the study was to establish the best cut-off value for the homeostatic model assessment (HOMA) index in identifying children and adolescents with the metabolic syndrome. The study included 72 non-obese and 68 obese children aged 7 to 16 years. Obesity is defined using the criteria proposed by Cole et al., being included as metabolic syndrome variables waist circumference, systolic blood pressure, diastolic blood pressure and seric values of glucose, uric acid, fasting insulin, leptin, triglycerides and HDL-cholesterol. Children were considered as having the metabolic syndrome when four or more characteristics showed abnormal values. The HOMA index was calculated as the product of the fasting plasma insulin level (microU/mL) and the fasting plasma glucose level (mmol/L), divided by 22.5. HOMA index cut-offs from the 5th to the 95th percentile were used. A receiver operating characteristic (ROC) curve was generated using the different HOMA cut-offs for the screening of the metabolic syndrome. The areas under the ROC curve, 95% confidence intervals, and the point to the ROC curve closest to 1, were calculated. The area under the ROC curve was 0.863 (95% C.I.: 0.797, 0.930). The point closest to 1 corresponds to the 60th percentile of the HOMA index distribution in our sample. HOMA index value at the 60th percentile was 2.28. Cut-off values corresponding to a range of HOMA index from the 50 to the 75 percentile, showed similar distances to 1. HOMA index values for percentiles 50 to 75 ranged from 2.07 to 2.83. In conclusion, HOMA index could be a useful tool to detect children and adolescents with the metabolic syndrome. HOMA cut-off values need to be defined in the paediatric population; however, values near to 3 seem to be adequate.

In developed countries, obesity prevalence has strongly increased in the last decades. This has also been observed in children and adolescents. Until recently, type 2 diabetes mellitus was considered very rare among children and adolescents; however, in the last decades, some cases have been observed mainly in obese adolescents of some minority populations. The aim of our study was to assess the prevalence of type 2 diabetes, impaired glucose tolerance (IGT) and insulin resistance, and the metabolic features, in obese children and adolescents. We have studied 95 obese children and adolescents, 53 males and 42 females, aged 4-16 years. The prevalence of IGT in obese children and adolescents studied was 7.4%; there was not any child with type 2 diabetes. Fasting glucose and insulin serum concentrations did not show significant differences between obese children with or without IGT; however, 120 minutes after an oral glucose tolerance test, glucose and insulin serum concentrations showed statistically significant differences between both groups. Insulin resistance is defined as a HOMA index higher than 4. The prevalence of insulin resistance in obese children studied was 35.8%. Trygliceride serum concentrations were higher and HDL-C serum concentrations were lower in obese children with IGT than in those without IGT, but the differences were not statistically significant. IGT and insulin resistance are frequent in obese children and adolescents; early treatment in obese children and adolescents with IGT constitutes a strategy of reversing progression to beta-cell failure and in preventing type 2 diabetes.

In children and adolescents from developed countries, obesity prevalence has strongly increased in the last decades and insulin resistance and impaired glucose tolerance are frequently observed. Some dietary components such as low glycemic index foods and dietary fibre could be used in order to improve glucose homeostasis in these children. Psyllium or ispaghula husk (the husk of the seeds of Plantago ovata) is a mixture of neutral and acid polysaccharides containing galacturonic acid with a ratio of soluble/insoluble fibre of 70/30. Some foods could potentially be enriched with psyllium, like breads, breakfast cereals, pasta and snack foods. The aim of this review was to assess the usefulness of psyllium in the management of obese children and adolescents with abnormalities of carbohydrate and lipid metabolism. After psyllium supplementation, the percentage change in postprandial glucose in type 2 diabetes patients, ranged from -12.2 to -20.2%. In hypercholesterolemic children, the effect of psyllium in LDL-cholesterol serum concentrations ranged from 2.78 to -22.8%; the effect in HDL-cholesterol from -4.16 to 3.05%; and the effect on triglycerides from 8.49 to -19.54%. The reviewed evidence seems to show that psyllium improves glucose homeostasis and the lipid and lipoprotein profile; however, more well controlled trials and further studies are needed to clarify it's effects and the mechanisms involved.

The aim of this study was to investigate the frequency of metabolic syndrome (MS) variables in a group of spanish obese children and adolescents, to asses MS prevalence in this population and to describe it's relationship with other metabolic risk factors. 103 children were studied : 54 male and 49 female, mean age 10.08+/-2.3 with exogenous obesity. Obesity was defined when BMI was higher than the age and sex specific equivalent to 30 kg/m(2) in adults. MS variables considered were waist circumference, blood pressure, fasting blood triglycerides, fasting glucose/insulin and HDL-cholesterol. The children were considered as having the MS when three or more characteristics showed abnormal values according to Cook and De Ferranti definitions. HOMA index, ApoB and ApoA1 were studied too. The most frequent features of the metabolic syndrome were excess waist circumference and hypertension. The MS markers with the lowest frequency were dyslipidemia and fasting hyperglicemia. MS prevalence was 29,9% (Cook et al. criteria) and 50% (De Ferranti et al. criteria). Fasting insulin and HOMA index values increased significantly (p < 0.05) when three or more abnormalities of the MS variables were present. Apo B increased significantly only in females (p < 0.05) and Apo Al decreased significantly (p < 0.05) in both sexes when MS was present. Adequate metabolic syndrome risk factors criteria, mainly cut-off values, need to be defined in the European paediatric population.