João P B Vieira-Filho

CEP America, Emeryville, California, United States

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Publications (8)15.01 Total impact

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    ABSTRACT: Aims To examine the properties of HbA1c to detect diabetes and IGT in adult Brazilian Xavante Indians, a high risk population for diabetes. Methods The survey was carried out between October 2010 and January 2012 and based on a 75 g oral glucose tolerance test (OGTT). Basal and 2 hour capillary glycaemia were measured by HemoCue Glucose 201+; HbA1c using an automated high-performance liquid chromatography analyzer (Tosoh G7). Results 630 individuals aged ≥ 20 years were examined and 80 had a previous diagnosis of diabetes. Sensitivity, specificity and accuracy for HbA1c ≥ 6.5% (≥ 48 mmol/mol) were 71.3%, 90.5% and 87.2%. The areas under the ROC curve (AUC) was 0.88 (95%CI: 0.83-0.93). To identify IGT, HbA1c values between 5.7% and 6.4% (39 - 47 mmol/mol) presented sensitivity, specificity, and accuracy of 87.2%, 24.7% and 51.4%, with an AUC of 0.62 (95%CI: 0.57-0.67). Conclusions The ADA/WHO proposed cut-off of 6.5% (48 mmol/mol) for HbA1c was adequate to detect diabetes among the Xavante. However, the performance of the ADA proposed cut-off points for pre-diabetes, when used to detect IGT was inadequate and should not be recommended.
    Diabetes Research and Clinical Practice. 09/2014;
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    ABSTRACT: To estimate the prevalence of diabetes, hypertension, obesity, and describe demographic, anthropometric and medical characteristics, in a genetically distinct population: the Brazilian Xavante Indians. Population-based survey carried out among 948 Xavante from Mato Grosso, Brazil. Fasting and 2-hour after 75 g glucose capillary glycemia were measured by a portable glucometer (HemoCue Glucose201+). Diabetes was defined according to WHO criteria. Anthropometric data and medical characteristics were measured, and fat mass (%) was evaluated using bioelectrical impedance. Blood pressure was measured by an automated device (OMRON 742INTC), and hypertension was defined according to WHO criteria. Age-adjusted prevalence rates with 95% confidence intervals were diabetes: 28.2% (25.3-31.1) in general, 18.4% (14.9-22.2) in men and 40.6% (36.2-45.1) in women (P<.001); impaired glucose tolerance: 32.3% (20.5-26.0) in general, 29.7% (25.4-33.9) in men and 34.4% (30.2-38.8) in women (P>.05); hypertension: 17.5% (15.1-19.9) in general. Obesity was found in 50.8% of the individuals. Fat mass (%) was associated with diabetes in men (P<.05) and women (P<.05). Thigh circumference and waist/ thigh ratio were lower in those with diabetes, in men and women (P<.001). The high prevalence of diabetes and obesity in Xavante is likely related to their recent change in food habits and physical activities. Our results should raise awareness about the magnitude of this health problem and also indicate that it could increase dramatically in the future if no preventive actions are adopted.
    Ethnicity & disease 01/2014; 24(1):35-40. · 1.12 Impact Factor
  • Diabetes Care 03/2004; 27(2):621-2. · 7.74 Impact Factor
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    ABSTRACT: Hyperhomocysteinemia is a risk factor for cardiovascular disease. C677T mutation at the MTHFR gene and deficiencies of folic acid and vitamin B-12 may account for elevation of total homocysteine (tHcy). Ninety Brazilian Parkatêjê Indians (90.0% of the population without admixture, aged > or = 20 years) were studied. Hyperhomocysteinemia was observed in 26.7% of the Indians. No case of vitamin B-12 deficiency was detected. Folic acid deficiency was found in 43.3% of the subjects. Rates of mutated allele 677T and TT genotype were 40.7% and 14.0%, respectively. Prevalence of hypertension, dyslipidemia, smoking, WHR > or = 0.9, BMI > or = 25 kg/m2 and chronic alcohol use were 4.4%, 44.4%, 25.6%, 72.2%, 67.8%, and 0.0%, respectively. All creatinine values were normal. Natural logarithmic (ln) tHcy showed no correlation with age, but was positively correlated with systolic (r = 0.22) and diastolic (r = 0.21) blood pressure and triglycerides (r = 0.39) and inversely correlated with folic acid (r = -0.40) adjusted for age and sex. Total homocysteine (tHcy) was higher among TT genotype (P < .001). The multiple linear regression model, containing variables for sex, folic acid, TT genotype, and triglycerides, explained 50.0% of the variation of the ln tHcy. In summary, high rates of cardiovascular risk factors were discovered. C667T mutation and folic acid deficiency can explain, at least in part, the observed hyperhomocysteinemia.
    Ethnicity & disease 02/2004; 14(1):49-56. · 1.12 Impact Factor
  • Ethnicity & disease 02/2004; 14(1):159. · 1.12 Impact Factor
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    ABSTRACT: The Parkatêjê Indians, belonging to the Jê group and inhabiting the Mãe Maria Reservation in the southeast of the state of Pará in the Amazon Region of Brazil, have suffered rapid and intensive cultural changes in recent years. This survey was designed to characterize the metabolic profile and the frequency of cardiovascular risk factors in this community. Ninety subjects (90.0% of the adult population without admixture) were investigated. Anthropometric measurements were performed and the following clinical characteristics measured: glycemia, serum insulin and proinsulin (fasting and 2-hr post 75 g of glucose load), beta-cell function (%B) and insulin sensitivity (%S) estimated by HOMA, HbA1c, GAD65 antibody, serum lipids, uric acid, creatinine, leptin, and blood pressure. Information about alcohol use, smoking, and medical history was obtained through individual interviews. The prevalences were: overweight, 67.8%; obesity, 14.4%; central obesity, 72.2%; hypertension, 4.4%; dyslipidemia, 44.4%; hyperuricemia, 5.6%; GAD65 antibody positivity, 4.4%; smoking, 25.6%; chronic alcohol use, 0.0%. One case of impaired glucose tolerance (1.1%) and one case of impaired fasting glycemia (1.1%) were diagnosed during this study and one case of diabetes (1.1%) was diagnosed previously. The diabetic woman was excluded from the analyses involving HbA1c, glycemia, insulin, proinsulin, %B, and %S. All creatinine values were normal. Blood pressure did not correlate with age, anthropometric measurements, insulin, proinsulin, and natural logarithm (ln) transformed %S. After adjustment for age and sex, there were positive correlations between total cholesterol and body mass index (BMI; r = 0.24), triglycerides and BMI (r = 0.44), triglycerides and waist-to-hip ratio (WHR; r = 0.52), In leptin and BMI (r = 0.41), In leptin and WHR (r = 0.29), uric acid and systolic blood pressure (r = 0.34), uric acid and triglycerides (r = 0.22). Systolic (r = 0.04; r = 0.70) and diastolic (r = 0.14; p = 0.18) blood pressure did not correlate with BMI. Ln leptin had a weak positive correlation with 2-hr insulin (r = 0.14) adjusted for age, sex, and BMI. The multiple linear regression model containing the variables sex, BMI, and 2-hr insulin concentrations explained 77.2% of the variation of ln leptin. In conclusion, the high rates of cardiovascular risk factors found among these Indians point to there being a high-risk group to develop diabetes and cardiovascular diseases. To reduce this risk they need to receive preventive interventions.
    Human Biology 03/2003; 75(1):31-46. · 1.52 Impact Factor
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    ABSTRACT: The Parkatêjê Indians, belonging to the Jê group and inhabiting the Mãe Maria Reservation in the southeast of the state of Pará in the Amazon Region of Brazil, have suffered rapid and intensive cultural changes in recent years. This survey was designed to characterize the metabolic profile and the frequency of cardiovascular risk factors in this community. Ninety subjects (90.0% of the adult population without admixture) were investigated. Anthropometric measurements were performed and the following clinical characteristics measured: glycemia, serum insulin and proinsulin (fasting and 2-hr post 75 g of glucose load), ß-cell function (%B) and insulin sensitivity (%S) estimated by HOMA, HbA1c, GAD65 antibody, serum lipids, uric acid, creatinine, leptin, and blood pressure. Information about alcohol use, smoking, and medical history was obtained through individual interviews. The prevalences were: overweight, 67.8%; obesity, 14.4%; central obesity, 72.2%; hypertension, 4.4%; dyslipidemia, 44.4%; hyperuricemia, 5.6%; GAD65 antibody positivity, 4.4%; smoking, 25.6%; chronic alcohol use, 0.0%. One case of impaired glucose tolerance (1.1%) and one case of impaired fasting glycemia (1.1%) were diagnosed during this study and one case of diabetes (1.1%) was diagnosed previously. The diabetic woman was excluded from the analyses involving HbA1c, glycemia, insulin, proinsulin, %B, and %S. All creatinine values were normal. Blood pressure did not correlate with age, anthropometric measurements, insulin, proinsulin, and natural logarithm (ln) transformed %S. After adjustment for age and sex, there were positive correlations between total cholesterol and body mass index (BMI; r = 0.24), triglycerides and BMI (r = 0.44), triglycerides and waist-to-hip ratio (WHR; r = 0.52), ln leptin and BMI (r = 0.41), ln leptin and WHR (r = 0.29), uric acid and systolic blood pressure (r = 0.34), uric acid and triglycerides (r = 0.22). Systolic (r = 0.04; r = 0.70) and diastolic (r = 0.14; p = 0.18) blood pressure did not correlate with BMI. Ln leptin had a weak positive correlation with 2-hr insulin (r = 0.14) adjusted for age, sex, and BMI. The multiple linear regression model containing the variables sex, BMI, and 2-hr insulin concentrations explained 77.2% of the variation of ln leptin. In conclusion, the high rates of cardiovascular risk factors found among these Indians point to there being a high-risk group to develop diabetes and cardiovascular diseases. To reduce this risk they need to receive preventive interventions.
    Human Biology 01/2003; 75(1):31-46. · 1.52 Impact Factor
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    Arquivos Brasileiros de Endocrinologia & Metabologia 06/2002; 46(3):260-268. · 0.88 Impact Factor