Objective:To evaluate the use of the 13C-glucose breath test (13C-GBT) for insulin resistance (IR) detection in adolescents through comparison with fasting and post-glucose stimulus surrogates.Methods:One hundred thirty-three adolescents aged between 10 and 16 years received an oral glucose load of 1.75 g per kg of body weight dissolved in 150 mL of water followed by an oral dose of 1.5 mg/kg of U-13C-Glucose, without a specific maximum dose. Blood samples were drawn at baseline and 120 minutes, while breath samples were obtained at baseline and at 30, 60, 90, 120, 150, and 180 minutes. The 13C-GBT was compared to homeostasis model assessment (HOMA) IR (≥p95 adjusted by gender and age), fasting plasma insulin (≥p90 adjusted by gender and Tanner stage), results of 2-h oral glucose tolerance test (OGTT), insulin levels (≥65 μU/mL) in order to determine the optimal cut-off point for IR diagnosis.Results:13C-GBT data, expressed as adjusted cumulative percentage of oxidized dose (A% OD), correlated inversely with fasting and post-load IR surrogates. Sexual development alters A% OD results, therefore individuals were stratified into pubescent and post-pubescent. The optimal cut-off point for the 13C-GBT in pubescent individuals was 16.3% (sensitivity=82.8% & specificity=60.6%) and 13.0% in post-pubescents (sensitivity=87.5% & specificity=63.6%), when compared to fasting plasma insulin. Similar results were observed against HOMA and 2-h OGTT insulin.Conclusion:The 13C-GBT is a practical and non-invasive method to screen for IR in adolescents with reasonable sensitivity and specificity.

Our results demonstrate that the 13C-glucose breath test could be a valid screening method to identify MS in adolescents.

Objective:The aim of this study was to determine optimal cut-off points for fasting and post-glucose stimulus surrogates of insulin resistance to predict metabolic syndrome in adolescents according to several definitions.Methods:One hundred fifty-five adolescents living in Mexico City were enrolled during 2011 and 2012. Waist circumference and blood pressure were recorded. Subjects received an oral glucose load of 1.75 g per kg up to a maximum dose of 75 g. Blood samples were drawn at baseline and 120 minutes. Concentrations of plasma glucose, triglycerides, high-density lipoprotein cholesterol and insulin were determined.Results:The frequency of metabolic syndrome showed a large variability when using a variety of published definitions; in contrast, the optimal cut-off points for fasting insulin, homeostatic model assessment of insulin resistance and two-hour oral glucose tolerance test insulin were very similar in almost all the definitions considered and had adequate diagnostic performance: area under the curve >0.869, sensitivity >0.835 and specificity >0.755. Insulin resistance surrogates had substantial agreements with Ford, Cook and Salas definitions (Kappa~0.62; agreement~82%); moderate agreement was observed for International Diabetes Federation, Cruz and Ferranti definitions (Kappa~0.41–0.59; agreement~77%).Conclusions:Insulin resistance surrogates may be a better approach for metabolic syndrome assessment in an adolescent population because of reduced variability and a higher predictive value.

The type of fat consumed in the Mexican diet could predispose to the development of Metabolic Syndrome (MS) which has been associated with an increased risk to develop cardiovascular disease and type 2 diabetes mellitus. Our study included adolescents between 12 and 16 years of age, divided in two groups: Control Group (n = 31) and MS Group (n = 44). Waist circumference, blood pressure, fasting glucose, triglycerides, and HDL-cholesterol were determined. Erythrocytes’ fatty acids methyl esthers were quantified using gas chromatography with ionized flame detector. We identified 16 fatty acids (FA) with chain lengths from C12 to C24, with emphasis in four trans FA (TFA) isomers: vaccenic (C18:1n7t), elaidic (C18:1n9t), linoelaidic (C18:2n6t), and conjugated linoelaidic acids (C18:2n7t). MS Group had a less proportion of: myristic (C14), palmitoleic (C16:1), C18:1n7t, and linoleic acids (C18:2); and a higher one of C18:1n9t, C18:2n7t, and nervonic acids (C24:1) when compared to the control group. C24:1 and C18:1n9t had a significant positive association with MS (OR = 14.17 and OR = 12.94, respectively); whereas C14 (OR = 0.14), C18:1n7t (OR = 0.14), and C18:2 (OR = 0.22) appear to have a protective effect against the disease. The proportion of specific FAs in erythrocytes’ membranes differs between adolescents with MS and healthy controls; these FA not only showed a strong association with MS, but also correlated with most of its individual components. Interestingly, TFA displayed an antagonic behavior; while C18:1n9t had a strong association with MS, apparently C18:1n7t confers a protective effect; these results suggest that analyzing each TFA separately will constitute a more accurate approach to determine the role of TFAs in the pathogenesis of MS or other related metabolic disorders.