The TyG index was evaluated as a surrogate method for estimation of insulin resistance (IR). TyG index correlated with adiposity, metabolic and atherosclerosis markers related to IR and presented a moderate degree of agreement with hyperglycemic clamp. TyG index represents an accessible tool for assessment of IR in clinical practice.

Neck circumference measurements are an alternative and innovative approach for determining body fat distribution. The NC is positively associated with MetS risk factors, IR and VF, with established cut-off values for the prediction of MetS and IR.

Objective: To investigate cut-off values for HOMA1-IR and HOMA2-IR to identify insulin resistance (IR) and metabolic syndrome (MS), and to assess the association of the indexes with components of the MS. Methods: Nondiabetic subjects from the Brazilian Metabolic Syndrome Study were studied (n = 1,203, 18 to 78 years). The cut-off values for IR were determined from the 90 th percentile in the healthy group (n = 297) and, for MS, a ROC curve was generated for the total sample. Results: In the healthy group, HOMA-IR indexes were associated with central obesity, triglycerides and total cholesterol (p < 0.001).

Objective: To verify the prevalence of metabolic syndrome and insulin resistance in obese adolescents and its relationship with different body composition indicators. Methods: A cross-sectional study comprising 79 adolescents aged ten to 18 years old. The assessed body composition indicators were: body mass index (BMI), body fat percentage, abdominal circumference, and subcutaneous fat. The metabolic syndrome was diagnosed according to the criteria proposed by Cook et al. The insulin resistance was determined by the Homeostasis Model Assessment for Insulin Resistance (HOMA-IR) index for values above 3.16. The analysis of ROC curves was used to assess the BMI and the abdominal circumference, aiming to identify the subjects with metabolic syndrome and insulin resistance. The cutoff point corresponded to the percentage above the reference value used to diagnose obesity. Results: The metabolic syndrome was diagnosed in 45.5% of the patients and insulin resistance, in 29.1%. Insulin resistance showed association with HDL-cholesterol (p=0.032) and with metabolic syndrome (p=0.006). All body composition indicators were correlated with insulin resistance (p<0.01). In relation to the cutoff point evaluation, the values of 23.5 and 36.3% above the BMI reference point allowed the identification of insulin resistance and metabolic syndrome. The best cutoff point for abdominal circumference to identify insulin resistance was 40%. Conclusions: All body composition indicators, HDL-cholesterol and metabolic syndrome showed correlation with insulin resistance. The BMI was the most effective anthropometric indicator to identify insulin resistance.

RESUMOA disfunção das células-e a resistência insulínica são anormalidades metabólicas inter-relacionadas na etiologia do diabetes tipo 2. Em diversos países, tem sido observado o aumento da prevalência de obesidade e diabetes em associação com a presença da resistência insulínica. Nesse contexto, é útil a mensuração da resistência insulínica e da capacidade funcional das células-nos indivíduos. Os índices Homeostasis Model Assessment (HOMA) têm sido amplamente utilizados, representando uma das alternativas para avaliação desses parâmetros, principalmente por figurarem um método rápido, de fácil aplicação e de menor custo. Esta revisão discute sobre a origem e a evolução dos índices HOMA, bem como as particularidades do método, abordando aspectos relacionados à sua validação e aos pontos de corte existentes para sua interpretação. Beta-cell dysfunction and insulin resistance are interrelated metabolic abnormalities in the aetiology of Type 2 Diabetes. In several countries, increases in the prevalence of obesity and diabetes have been observed in association with the presence of insulin resistance. In this context, measurement of insulin resistance and beta-cell function is useful. The HOMA indexes (Homeostasis Model Assessment) have been widely used, representing an alternative for the evaluation of these parameters, particularly as a fast, easy and cheap method. This review discusses the origin and evolution of the HOMA index, as well as details of the method, analyzing features related to its validation and the cutoff limits for its interpretation. INTRODUÇÃOA MANUTENÇÃO DA GLICEMIA NORMAL DEPENDE principalmente da capacidade funcional das células-pancreáticas (BcC) em secretar insulina e da sensibilidade tecidual à ação da insulina (SI) (1). A disfunção das células-e a resistência insulínica (RI) são anormalidades metabólicas inter-relacionadas na etiologia do diabetes melito do tipo 2 (DM2) (1,2). A RI caracteriza-se por falhas das células-alvo em responder aos níveis normais de insulina circulantes, revisão ANA CAROLINA J. VASQUES

Conflicting data concerning the association between obesity and differentiated thyroid cancer (DTC) may be attributed to the lack of records showing dietary intake and inadequate evaluation of nutrient composition. We evaluated 115 DTC patients carefully paired with 103 healthy control individuals by using a structured questionnaire, including a 24-h recordatory during 3 days, to investigate calorie intake and macronutrient (proteins, carbohydrates, and lipids) composition of the diet. We observed that excess weight (body mass index > 25 kg/m(2)) increased individual susceptibility to DTC [odds ratio (OR) = 3.787; 95% confidence interval (CI) = 1.115-6.814; P < 0.0001). This augmented risk was evident in women (OR = 1.925; 95% CI = 1.110-3.338; P = 0.0259) but not in men (P = 0.3498). Excess calorie intake was more frequent in patients with DTC than in controls (OR = 5.890; 95% CI = 3.124-11.103; P < 0.0001), and both excess protein (OR = 4.601; 95% CI = 1.634-12.954; P = 0.0039) and carbohydrate (OR = 4.905; 95% CI = 2.593-9.278; P < 0.0001) consumption were associated with an increased risk of DTC, contrarily to lipid/fiber intake and physical activity (P = 0.894 and 0.5932, respectively). In conclusion, our data indicate that overweight and risk of DTC are associated with higher protein and carbohydrate consumption than the rates recommended by the World Health Organization. The nutritional orientation should be part of preventive strategy targets designed to combat the increasing incidence of both obesity and DTC.

resuMo Objetivos: Avaliar a habilidade de indicadores antropométricos e de composição corporal em identificar a resistência à insulina (RI), determinando-se os pontos de corte para os que apresentarem melhor eficácia. Métodos: Foram avaliados 138 homens. Determinou-se: perímetro da cintura (PC), diâmetro abdominal sagital (DAS), índice de conicidade (IC), índice de massa corporal (IMC), percentual de gordura corporal (%GC), índice sagital (IS) e relações cintura-estatura (RCE), cintura-quadril (RCQ) e cintura-coxa (RCCoxa). A RI foi avaliada pelo HOMA-IR. Utilizou-se análise de correlação e análise ROC, com determinação das áreas abaixo da curva (AUC). descritores Resistência à insulina; HOMA; perímetro da cintura; diâmetro abdominal sagital; obesidade aBstract Objective: To assess the ability of anthropometric and body composition indicators in identifying insulin resistance (IR), determining cut-off points for those showing the best efficacy. Method: 138 men were evaluated. Waist perimeter (WP), sagittal abdominal diameter (SAD), conicity index, body mass index (BMI), body fat percent, sagittal index, and the waist-to-height, waist-to-hip and waist-to-thigh ratios were determined. IR was assessed by the HOMA-IR index. Statistical analysis consisted of Spearman correlation coefficient and ROC (receiver operating characteristic) curves, calculating the area under the curve (AUC). Results: SAD (r=0.482, AUC=0.746) and WP (r=0.464, AUC=0.739) showed stronger correlations with the HOMA-IR and greater ability to identify IR (p<0.001), being 89.3 cm and 20.0 cm the best cut-offs, respectively. Conclusion: The anthropometric indicators of central obesity, WP and SAD, have shown greater ability to identify IR in men. We encourage studies in women and elderly people in search of the best cut-off points for the entire population. Arq Bras endocrinol metab. 2009;53(1):72-79.

BackgroundSagittal abdominal diameter (SAD) has been proposed as a surrogate marker of insulin resistance (IR). However, the utilization of SAD requires specific validation for each ethnicity. We aimed to investigate the potential use of SAD, compared with classical anthropometrical parameters, as a surrogate marker of IR and to establish the cutoff values of SAD for screening for IR.MethodsA multicenter population survey on metabolic disorders was conducted. A race-admixtured sample of 824 adult women was assessed. The anthropometric parameters included: BMI, waist circumference (WC), waist-to-hip ratio and SAD. IR was determined by a hyperglycemic clamp and the HOMA-IR index.ResultsAfter adjustments for age and total body fat mass, SAD (r = 0.23 and r = -0.70) and BMI (r = 0.20 and r = -0.71) were strongly correlated with the IR measured by the HOMA-IR index and the clamp, respectively (p < 0.001). In the ROC analysis, the optimal cutoff for SAD in women was 21.0 cm. The women with an increased SAD presented 3.2 (CI 95%: 2.1-5.0) more likelihood of having IR, assessed by the HOMA-IR index compared with those with normal SAD (p < 0.001); whereas women with elevated BMI and WC were 2.1 (95% CI: 1.4-3.3) and 2.8 (95% CI: 1.7-4.5) more likely to have IR (p < 0.001), respectively. No statistically significant results were found for waist-to-hip ratio.ConclusionsSAD can be a suitable surrogate marker of IR. Understanding and applying routine and simplified methods is essential because IR is associated with an increased risk of obesity-related diseases even in the presence of normal weight, slight overweight, as well as in obesity. Further prospective analysis will need to verify SAD as a determinant of clinical outcomes, such as type 2 diabetes and cardiovascular events, in the Brazilian population.