The threshold value for identifying insulin resistance (HOMA-IR) in an admixed adolescent population: A hyperglycemic clamp validated study.

Objective: To validate the homeostasis model assessment (HOMA) of insulin resistance (IR) as a surrogate to the hyperglycemic clamp to measure IR in both pubertal and postpubertal adolescents, and determine the HOMA-IR cutoff values for detecting IR in both pubertal stages. Subjects and methods: The study sample comprised 80 adolescents of both sexes (aged 10-18 years; 37 pubertal), in which IR was assessed with the HOMA-IR and the hyperglycemic clamp. Results: In the multivariable linear regression analysis, adjusted for sex, age, and waist circumference, the HOMA-IR was independently and negatively associated with the clamp-derived insulin sensitivity index in both pubertal (unstandardized coefficient - B = -0.087, 95% confidence interval [CI] = -0.135 to -0.040) and postpubertal (B = -0.101, 95% CI, -0.145 to -0.058) adolescents. Bland-Altman plots showed agreement between the predicted insulin sensitivity index and measured clamp-derived insulin sensitivity index in both pubertal stages (mean =-0.00 for pubertal and postpubertal); all P > 0.05. The HOMA-IR showed a good discriminatory power for detecting IR with an area under the receiver operator characteristic curve of 0.870 (95% CI, 0.718-0.957) in pubertal and 0.861 (95% CI, 0.721-0.947) in postpubertal adolescents; all P < 0.001. The optimal cutoff values of the HOMA-IR for detecting IR were > 3.22 (sensitivity, 85.7; 95% CI, 57.2-98.2; specificity, 82.6; 95% CI, 61.2-95.0) for pubertal and > 2.91 (sensitivity, 63.6; 95% CI, 30.8-89.1, specificity, 93.7; 95%CI, 79.2-99.2) for postpubertal adolescents. Conclusion: The threshold value of the HOMA-IR for identifying insulin resistance was > 3.22 for pubertal and > 2.91 for postpubertal adolescents.

Insulin Resistance in Congenital Adrenal Hyperplasia is Compensated for by Reduced Insulin Clearance.

CONTEXT: Congenital adrenal hyperplasia (CAH) patients have potential normal longevity. However, a greater risk for cardiovascular disease has been reported. Insulin resistance and hyperinsulinemia have been described in CAH patients, whereas the prevalence of overt type 2 diabetes is not higher in CAH than in normal population. OBJECTIVE: To examine the contributions of insulin secretion and of hepatic insulin clearance to compensatory hyperinsulinemia in young insulin-resistant adults with classic CAH due to 21-hydroxylase deficiency (21-OHD). DESIGN: Cross-sectional. SETTING: University outpatient clinics. METHODS: Fifty-one participants: 21 controls, and 30 CAH (15 virilizing and 15 salt-wasting phenotypes), female/male (33/18), age (mean [SD]): 24.0 (3.6) years, body mass index: 24.6 (4.9)kg/m2 with normal glucose tolerance, were submitted to a hyperglycemic clamp study. MAIN OUTCOME MEASURES: Insulin sensitivity, beta cell function, and hepatic insulin clearance using appropriate modeling. RESULTS: We found an increased insulin resistance in 21-OHD. The systemic hyperinsulinemia (posthepatic insulin delivery) was elevated in CAH patients. No increases were observed in insulin secretory rate (beta cell function) in the first phase or during the hyperglycemic clamp. The increase in insulin concentrations was totally due to a ~33% reduction in insulin clearance. CONCLUSION: 21-OHD nonobese subjects have reduced insulin sensitivity and beta cell response unable to compensate for the insulin resistance, probably due to overexposure to glucocorticoids. Compensatory hyperinsulinemia is most related with reduced hepatic insulin clearance. The exclusive adaptation of the liver acts as a gating mechanism to regulate the access of insulin to insulin-sensitive tissues to maintain glucose homeostasis.

Homeostatic model assessment of adiponectin (HOMA-Adiponectin) as a surrogate measure of insulin resistance in adolescents: Comparison with the hyperglycaemic clamp and homeostatic model assessment of insulin resistance.

BACKGROUND: Studies on adults have reported inverse association between the homeostatic model assessment (HOMA) of adiponectin (HOMA-Adiponectin) and the insulin resistance assessed by the glucose clamp technique. To our knowledge, in the pediatric population this association has not been previously investigated. OBJECTIVES: To evaluate the association between the HOMA-Adiponectin and the insulin resistance assessed by the glucose clamp technique in adolescents, and to compare the accuracy of HOMA-Adiponectin and HOMA-insulin resistance (HOMA-IR) for identifying insulin resistance. METHODS: This was a cross-sectional study of 56 adolescents (aged 10-18 years). Insulin resistance was assessed using the HOMA-IR, HOMA-Adiponectin and the hyperglycaemic clamp technique. The clamp-derived insulin sensitivity index, HOMA-Adiponectin, and HOMA-IR were log-transformed to get closer to a normal distribution before analysis. RESULTS: In the multivariable linear regression analysis controlling for sex and Tanner stage, HOMA-Adiponectin was inversely associated with the clamp-derived insulin sensitivity index (unstandardized coefficient [B] = -0.441; P < 0.001). After additional adjustment for waist circumference-to-height ratio, this association remained significant (B = -0.349; P = < 0.001). Similar results were observed when HOMA-IR replaced HOMA-Adiponectin in the model (B = -1.049 and B = -0.968 after additional adjustment for waist circumference-to-height ratio); all P < 0.001. The area under the receiver operating characteristic curve for predicting insulin resistance was 0.712 (P = 0.02) for HOMA-Adiponectin and 0.859 (P < 0.0001) HOMA-IR. CONCLUSIONS: The HOMA-Adiponectin was independently associated with insulin resistance and exhibited a good discriminatory power for predicting it. However, it did not show superiority over HOMA-IR in the diagnostic accuracy.

The threshold value for identifying insulin resistance (HOMA-IR) in an admixed adolescent population: A hyperglycemic clamp validated study

ABSTRACT Objectives: To validate the homeostasis model assessment (HOMA) of insulin resistance (IR) as a surrogate to the hyperglycemic clamp to measure IR in both pubertal and postpubertal adolescents, and determine the HOMA-IR cutoff values for detecting IR in both pubertal stages. Subjects and methods: The study sample comprised 80 adolescents of both sexes (aged 10-18 years; 37 pubertal), in which IR was assessed with the HOMA-IR and the hyperglycemic clamp. Results: In the multivariable linear regression analysis, adjusted for sex, age, and waist circumference, the HOMA-IR was independently and negatively associated with the clamp-derived insulin sensitivity index in both pubertal (unstandardized coefficient - B = −0.087, 95% confidence interval [CI] = −0.135 to −0.040) and postpubertal (B = −0.101, 95% CI, −0.145 to −0.058) adolescents. Bland-Altman plots showed agreement between the predicted insulin sensitivity index and measured clamp-derived insulin sensitivity index in both pubertal stages (mean = −0.00 for pubertal and postpubertal); all P > 0.05. The HOMA-IR showed a good discriminatory power for detecting IR with an area under the receiver operator characteristic curve of 0.870 (95% CI, 0.718-0.957) in pubertal and 0.861 (95% CI, 0.721-0.947) in postpubertal adolescents; all P < 0.001. The optimal cutoff values of the HOMA-IR for detecting IR were > 3.22 (sensitivity, 85.7; 95% CI, 57.2-98.2; specificity, 82.6; 95% CI, 61.2-95.0) for pubertal and > 2.91 (sensitivity, 63.6; 95% CI, 30.8-89.1, specificity, 93.7; 95%CI, 79.2-99.2) for postpubertal adolescents. Conclusion: The threshold value of the HOMA-IR for identifying insulin resistance was > 3.22 for pubertal and > 2.91 for postpubertal adolescents.

Association of Sleep Deprivation With Reduction in Insulin Sensitivity as Assessed by the Hyperglycemic Clamp Technique in Adolescents.

IMPORTANCE: The association between short sleep duration and decreased insulin sensitivity in adolescents has been described. However, to our knowledge, no studies have investigated this association measuring insulin sensitivity by the hyperglycemic clamp technique. OBJECTIVES: To compare the distributions of parameters of insulin resistance in adolescents with sleep deprivation vs adequate sleep, and to investigate the association between sleep deprivation and insulin sensitivity. DESIGN, SETTING, AND PARTICIPANTS: Cross-sectional multicenter study using data from the Brazilian Metabolic Syndrome Study conducted from June 29, 2011, to December 3, 2014, at an obesity outpatient clinic at the University of Campinas and public schools, with a convenience sample of 615 adolescents aged 10 to 19.9 years with a body mass index (BMI; calculated as weight in kilograms divided by height in meters squared) for age and sex at the fifth percentile or higher. A subsample of 81 adolescents underwent the hyperglycemic clamp technique. MAIN OUTCOMES AND MEASURES: The self-reported sleep duration was used to classify the population into 2 groups: adolescents with sleep deprivation (<8 hours/night) and adolescents with adequate sleep (≥8 hours/night). Insulin sensitivity was assessed using the hyperglycemic clamp technique. RESULTS: Among the 615 adolescents (56.3% female; median age, 15.9 years [interquartile range, 12.9-17.8 years]) included in the sample, the mean (SD) sleep duration was 7.9 (1.7) hours/night. The adolescents with sleep deprivation (n = 257) compared with those with adequate sleep (n = 358) had a higher median (interquartile range) age (17.0 [15.4-18.3] vs 14.1 [11.8-16.9] years), BMI (25.0 [21.2-29.3] vs 23.1 [19.5-27.6]), waist circumference (83.0 [73.5-95.4] vs 79.0 [68.5-91.0] cm), sagittal abdominal diameter (17.9 [15.8-20.8] vs 17.0 [15.0-19.8] cm), neck circumference (35.2 [33.0-38.0] vs 33.0 [30.0-35.5] cm), uric acid level (4.9 [4.0-5.8] vs 4.5 [3.7-5.5] mg/dL), and white blood cell count (7000 [5900-8200] vs 6600 [5600-7800] cells/µL) (all P < .05). Moreover, the adolescents with sleep deprivation had a lower median (interquartile range) insulin sensitivity index compared with those with adequate sleep (0.10 [0.05-0.21] vs 0.21 [0.09-0.33] mg · kgfat-free mass-1 · min-1 · mU/L × 100, respectively; difference, -0.01; 95% CI, -0.01 to -0.00; P = .02). After controlling for age and sex in the multivariate regression model, sleep deprivation remained an independent predictor for those variables. In the sleep deprivation group, BMI and central distribution of fat were higher in all categories of adiposity. CONCLUSIONS AND RELEVANCE: Sleep deprivation (<8 hours of sleep per night) is associated with centripetal distribution of fat and decreased insulin sensitivity in adolescents. Therefore, investigations of sleep duration and sleep quality in adolescents should be included in clinical practice to promote, through health education, the eradication of the health risks associated with sleep restriction.

Hypertriglyceridemic Waist Phenotype Indicates Insulin Resistance in Adolescents According to the Clamp Technique in the BRAMS Study.

OBJECTIVE: This study aimed to identify cutoff points for detecting hypertriglyceridemic waist phenotype (HTWP) in adolescents and to investigate the association of the HTWP with insulin resistance (IR) and metabolic syndrome components. METHODS: A multicentric cross-sectional study of 861 adolescents (10-19 years of age, 504 girls) was conducted. Pubertal stage, anthropometric, and laboratory parameters were assessed. IR was assessed by Homeostasis Model Assessment for Insulin Resistance (HOMA1-IR) index and hyperglycemic clamp (n = 80). HTWP was defined by the presence of increased plasma triglycerides (TGs) and increased waist circumference (WC) according to cutoff points obtained in ROC curve analysis given the HOMA1-IR index as a reference method. RESULTS: Cutoffs for WC and TGs, with a higher sum of sensitivity (S) and specificity (E), were, respectively: >84 cm (S:65.1%, E:71.9%) and >87 mg/dL (S:65.1%, E:73.4%) in pubertal girls; >88.5 cm (S:80.2%, E:60.2%) and >78 mg/dL (S:60.5%, E:53.2%) in postpubertal girls; >94 cm (S:73.1%, E:83.1%) and >79 mg/dL (S:61.5%, E:60.2%) in pubertal boys; and >99 cm (S:81.3%, E:78.7%) and >86 mg/dL in postpubertal boys (S:68.1%, E:60.7%). HTWP frequency was 27.5%. In the phenotype presence, after adjustment for age and pubertal stage, blood pressure and fasting glucose levels were elevated and high-density lipoprotein cholesterol was lower (p < 0.001). Adolescents with the HTWP showed more IR, evaluated both by the HOMA1-IR and by the clamp test (p < 0.003). CONCLUSION: The findings suggest HTWP as an IR status in adolescents. Cutoff point standardization for gender and pubertal stage, combined with the ease of application of the method, may allow their use for screening adolescents who would most benefit from lifestyle changes.

Neck circumference as a new anthropometric indicator for prediction of insulin resistance and components of metabolic syndrome in adolescents: Brazilian Metabolic Syndrome Study.

OBJECTIVE: To evaluate the correlation between neck circumference and insulin resistance and components of metabolic syndrome in adolescents with different adiposity levels and pubertal stages, as well as to determine the usefulness of neck circumference to predict insulin resistance in adolescents. METHODS: Cross-sectional study with 388 adolescents of both genders from ten to 19 years old. The adolescents underwent anthropometric and body composition assessment, including neck and waist circumferences, and biochemical evaluation. The pubertal stage was obtained by self-assessment, and the blood pressure, by auscultation. Insulin resistance was evaluated by the Homeostasis Model Assessment-Insulin Resistance. The correlation between two variables was evaluated by partial correlation coefficient adjusted for the percentage of body fat and pubertal stage. The performance of neck circumference to identify insulin resistance was tested by Receiver Operating Characteristic Curve. RESULTS: After the adjustment for percentage body fat and pubertal stage, neck circumference correlated with waist circumference, blood pressure, triglycerides and markers of insulin resistance in both genders. CONCLUSIONS: The results showed that the neck circumference is a useful tool for the detection of insulin resistance and changes in the indicators of metabolic syndrome in adolescents. The easiness of application and low cost of this measure may allow its use in Public Health services.

Obesity and asthma: association or coincidence?

OBJECTIVE: Asthma and obesity are among the major causes of morbidity in childhood and adolescence. Early obesity increases the chances of chronic degenerative diseases in adults. Although the concomitance or both clinical situations are being demonstrated in various studies, the intrinsic mechanisms of this association are still very little known. Therefore, the objective of this article was to review the main studies on the association of obesity and asthma and check if there is a cause-effect relation between them. SOURCES: Systematic review based on indexed data bases MEDLINE (PubMed) and SciELO. Original articles (cross-sectional, case-control, and prospective studies) and meta-analysis published in the period that ranges from January 1998 to January 2008 were reviewed. Studies published in English, Spanish, and Portuguese were researched. SUMMARY OF THE FINDINGS: Although there are various studies on growing prevalence of asthma and obesity, few of them establish cause-effect relations between them. Physiopathological mechanisms and factors involved in this process are still little known. CONCLUSION: Methodological rigor in future studies must seek for answers to better understand if there is association between asthma and obesity or if the relationship between both diseases is a coincidence.

Neck circumference as a new anthropometric indicator for prediction of insulin resistance and components of metabolic syndrome in adolescents: Brazilian Metabolic Syndrome Study / Circunferencia del cuello como un nuevo indicador antropométrico para predicción de resistencia a la insulina y componentes del síndrome metabólico en adolescentes: Brazilian Metabolic Syndrome Study - BRAMS / Circunferência do pescoço como um novo indicador antropométrico para predição de resistência à insulina e componentes da síndrome metabólica em adolescentes: Brazilian Metabolic Syndrome Study

To evaluate the correlation between neck circumference and insulin resistance and components of metabolic syndrome in adolescents with different adiposity levels and pubertal stages, as well as to determine the usefulness of neck circumference to predict insulin resistance in adolescents. METHODS: Cross-sectional study with 388 adolescents of both genders from ten to 19 years old. The adolescents underwent anthropometric and body composition assessment, including neck and waist circumferences, and biochemical evaluation. The pubertal stage was obtained by self-assessment, and the blood pressure, by auscultation. Insulin resistance was evaluated by the Homeostasis Model Assessment-Insulin Resistance. The correlation between two variables was evaluated by partial correlation coefficient adjusted for the percentage of body fat and pubertal stage. The performance of neck circumference to identify insulin resistance was tested by Receiver Operating Characteristic Curve. RESULTS: After the adjustment for percentage body fat and pubertal stage, neck circumference correlated with waist circumference, blood pressure, triglycerides and markers of insulin resistance in both genders. CONCLUSIONS: The results showed that the neck circumference is a useful tool for the detection of insulin resistance and changes in the indicators of metabolic syndrome in adolescents. The easiness of application and low cost of this measure may allow its use in Public Health services...

Evaluar la correlación de la circunferencia del cuello con resistencia a la insulina y con los componentes del síndrome metabólico en adolescentes con distintos niveles de adiposidad y estadios puberales, así como determinar la utilidad de la circunferencia del cuello como un parámetro en la predicción de resistencia a la insulina en adolescentes. MÉTODOS: Estudio transversal en el que se evaluó a 388 adolescentes de ambos sexos, de los 10 a los 19 años. Los adolescentes fueron sometidos a evaluación antropométrica y de composición corporal, incluyendo circunferencias del cuello y de la cintura, y la evaluación bioquímica. El estadio puberal se obtuvo mediante autoevaluación y la presión arterial, por el método de ausculta. Se evaluó la resistencia a la insulina por el Homeostasis Model Assessment-Insulin Resistence. La correlación entre dos variables fue evaluada con el coeficiente de corrrelación parcial ajustado para el porcentaje de grasa corporal y el estadio puberal. El desempeño de la circunferencia del cuello para identificar resistencia a la insulina fue evaluado por la Receiver Operating Characteristic Curve y se consideró p<0,05. RESULTADOS: Después del ajuste para el porcentaje de grasa corporal y estadio puberal, la circunferencia del cuello se correlacionó con la circunferencia de la cintura, presión arterial, triglicéridos y marcadores de resistencia a la insulina en ambos sexos. CONCLUSIONES: Los resultados demostraron que la circunferencia del cuello es una herramienta útil para detectar la resistencia a la insulina y la alteración en los indicadores de síndrome metabólico en adolescentes. La facilidad de aplicación y el bajo costo pueden hacer su uso viable en servicios de Salud Pública...

Avaliar a correlação da circunferência do pescoço com resistência à insulina e com os componentes da síndrome metabólica em adolescentes com diferentes níveis de adiposidade e estadios puberais, bem como determinar a utilidade da circunferência do pescoço como um parâmetro na predição de resistência à insulina em adolescentes. MÉTODOS: Estudo transversal no qual se avaliaram 388 adolescentes de ambos os sexos, de dez a 19 anos. Os adolescentes foram submetidos à avaliação antropométrica e de composição corporal, incluindo circunferências do pescoço e da cintura, e a avaliação bioquímica. O estadio puberal foi obtido por meio de autoavaliação e a pressão arterial, pelo método auscultatório. Analisou-se a resistência à insulina pelo Homeostasis Model Assessment-Insulin Resistance. A correlação entre duas variáveis foi verificada com o coeficiente de correlação parcial ajustado para o percentual de gordura corporal e o estadio puberal. O desempenho da circunferência do pescoço para identificar resistência à insulina foi testado pela Receiver Operating Characteristic Curve. RESULTADOS: Após ajuste para o percentual de gordura corporal e estadio puberal, a circunferência do pescoço correlacionou-se com circunferência da cintura, pressão arterial, triglicérides e marcadores de resistência à insulina em ambos os sexos. CONCLUSÕES: Os resultados demonstraram que a circunferência do pescoço é uma ferramenta útil para detectar a resistência à insulina e a alteração nos indicadores de síndrome metabólica em adolescentes. A facilidade de aplicação e o baixo custo podem viabilizar sua utilização...

Obesidade e asma: associação ou coincidência? [revisão] / Obesity and asthma: association or coincidence? [review]

Objetivo: A asma e a obesidade estão entre as maiores causas de morbidade na infância e adolescência. A obesidade precoce aumenta as chances de doenças crônicas degenerativas no adulto. Embora a concomitância de ambas as situações clínicas vem sendo demonstrada em vários estudos, os mecanismos intrínsecos dessa associação ainda são pouco conhecidos. Portanto, o objetivo deste artigo foi revisar os principais trabalhos sobre a associação de obesidade e asma e verificar se existe relação de causa e efeito entre ambas. Fontes dos dados: Revisão sistemática baseada em bases de dados indexadas MEDLINE (PubMed) e SciELO. Foram revisados artigos originais (transversal, caso-controle e prospectivo) e meta-análises publicados no período de janeiro de 1998 a janeiro de 2008. Foram pesquisados estudos divulgados em língua inglesa, espanhola e portuguesa. Síntese dos dados: Embora existam muitos estudos sobre as crescentes prevalências da asma e da obesidade, poucos estabelecem relações de causa e efeito entre ambas. Os mecanismos fisiopatológicos e os fatores envolvidos nesse processo ainda são pouco conhecidos. Conclusão: O rigor metodológico em estudos futuros deverá buscar respostas para melhor entender se existe associação entre asma e obesidade, ou se a relação entre ambas as doenças é coincidência.

Objective: Asthma and obesity are among the major causes of morbidity in childhood and adolescence. Early obesity increases the chances of chronic degenerative diseases in adults. Although the concomitance or both clinical situations are being demonstrated in various studies, the intrinsic mechanisms of this association are still very little known. Therefore, the objective of this article was to review the main studies on the association of obesity and asthma and check if there is a cause-effect relation between them. Sources: Systematic review based on indexed data bases MEDLINE (PubMed) and SciELO. Original articles (cross-sectional, case-control, and prospective studies) and meta-analysis published in the period that ranges from January 1998 to January 2008 were reviewed. Studies published in English, Spanish, and Portuguese were researched. Summary of the findings: Although there are various studies on growing prevalence of asthma and obesity, few of them establish cause-effect relations between them. Physiopathological mechanisms and factors involved in this process are still little known. Conclusion: Methodological rigor in future studies must seek for answers to better understand if there is association between asthma and obesity or if the relationship between both diseases is a coincidence.

Prevalência da amamentação em crianças menores de dois anos vacinadas nos centros de saúde escola / Breastfeeding prevalence among children less than two years old immunized in primary health care school services

OBJETIVO: Neste trabalho foi desenvolvido estudo transversal com o objetivo de verificar a prevalência da amamentação em 1 708 crianças menores de dois anos em Campinas, São Paulo. MÉTODOS: As informações sobre idade, sexo, serviço de saúde utilizado e alimentação foram obtidas por entrevistas com mães ou responsáveis durante a Campanha de Multivacinação de 2001. A amamentação foi classificada como exclusiva, predominante (incluindo outros líquidos, exceto leites), complementar (incluindo outros alimentos e/ou leites) e total (soma de exclusivo, predominante e complementar). RESULTADOS: A análise demonstrou que a mediana de amamentação exclusiva foi de 68 dias e a de amamentação total foi de 6,4 meses. No primeiro semestre de vida, 38,1 por cento das crianças estavam em amamentação exclusiva; 23,0 por cento em predominante e 14,9 por cento em complementar. No segundo semestre, 36,5 por cento das crianças recebiam leite materno; no terceiro 26,4 por cento e no quarto 13,9 por cento. Crianças usuárias dos serviços públicos e das unidades locais de saúde apresentaram menor risco de desmame do que as usuárias dos serviços privados e de serviços não locais (p<0,005). CONCLUSAO: Salienta-se a necessidade de estabelecimento de metas visando à amamentação exclusiva até seis meses de idade e total até dois anos ou mais, conforme recomendação da Organização Mundial da Saúde e do Ministério da Saúde.