Heart Disease Risk Factors In African Americans

182名非糖尿病非裔美国人(74名男性，108名女性)参与了这项研究。参与者的年龄范围从20岁到50岁不等。这一非裔美国人的样本可以被认为具有代表性，因为肥胖症(43%)、糖耐量低减(22%)和高血压(21%)的患病率与NHANES数据相似。NHANES代表国家健康和营养检查，是一项有数千人参与的全国性调查。参与者从非常苗条到非常肥胖不等。受试者的平均体重指数为30.6 kg/m2(范围为18.554.7)。体重指数是一种用来根据身高校正体重的数学方法。由于参与者的体重指数范围很广，因此有可能得出身体大小与胰岛素抵抗之间的关系的结论。我们在非裔美国人身上发现，男性腰围102厘米预示着胰岛素抵抗和肥胖。因此，我们完全同意国家胆固醇教育计划对白人的价值观。然而，在非裔美国女性中，我们发现腰围98厘米预示着胰岛素抵抗和肥胖。根据对白人女性的调查，国家胆固醇教育计划建议使用88厘米的腰围阈值。因此，我们的工作表明，有必要针对不同种族修改妇女准则。 甘油三酯升高和高密度脂蛋白降低被认为是胰岛素抵抗的血脂特征。然而，尽管甘油三酯升高是白人胰岛素抵抗的标志，但我们已经表明，甘油三酯不是非裔美国人胰岛素抵抗的标志。甘油三酯与胰岛素抵抗关系的研究已经成为这项研究的重要组成部分，参与这一方案的非裔美国人队列现在被称为非裔美国人甘油三酯和心血管风险的TARA。TARA的结果是如此令人印象深刻，以至于甘油三酯不是非裔美国人胰岛素抵抗的标记物的假设在1999年至2001年的NHANES数据中得到了检验。在这个关于白人、非裔美国人和墨西哥裔美国人的全国性数据集中，甘油三酯不是胰岛素抵抗的标志这一事实得到了证实。然而，甘油三酯在白人和墨西哥裔美国人中是胰岛素抵抗的标志。这再次表明有必要制定针对族裔的指导方针。与NHANES的这项工作正在进行中。 为了开发游离脂肪酸对胰岛素的敏感性指数，我们正在与数学家合作。建模工作正在进行中。二十世纪八十年代，理查德·N·伯格曼和他的同事建立了胰岛素对血糖水平影响的模型。由于影响游离脂肪酸水平的激素种类繁多，而且游离脂肪酸的生物变异范围比葡萄糖大得多，因此建立胰岛素对游离脂肪酸影响的模型是一个更大的挑战。为了建立一个模型，塔拉的150名参与者在3到6个小时内，在36个时间点频繁地进行了静脉血糖测试，测定了葡萄糖、胰岛素和游离脂肪酸的水平。复杂的多舱室模型正在进行中。

One hundred eighty-two nondiabetic African-Americans (74 Men, 108 Women) have participated. The age range of the participants is 20 to 50 years. This sample of African Americans can be considered representative because the prevalence of obesity (43%), glucose intolerance (22%) and hypertension (21%) is similar to NHANES data. NHANES stands for National Health and Nutrition Examination and is a nationwide survey with thousands of participants. The participants range from very lean to very obese. The mean body mass index of participants is 30.6 kg/m2 (range 18.5 54.7). Body mass index is a mathematical method used to correct weight for height. Due to the broad range of body mass index in the participants it is possible to make conclusions about the relationship of body size to insulin resistance. We have found in African American men that a waist circumference of 102 cm in men predicts both insulin resistance and obesity. Therefore we are completely in agreement with the National Cholesterol Education Program values for whites. However, in African American women we found that a waist circumference of 98 cm predicted both insulin resistance and obesity. Based on investigations in white women the National Cholesterol Education Program recommends that a waist circumference threshold of 88 cm be used. Therefore our work demonstrates the need for ethnic specific modifications of guidelines in women. Elevated TG and low HDL are considered lipid hallmarks of insulin resistance. However while elevated TG is a marker of insulin resistance in whites, we have shown that TG is not a marker of insulin resistance in African Americans. The investigation of the relationship of TG to insulin resistance has become such an important component of this research, that the cohort of African Americans participating in this protocol are now known as TARA for Triglyceride and Cardiovascular Risk in African Americans. Results from TARA were so impressive that the hypothesis that TG was not a marker of insulin resistance in African Americans was tested in NHANES data from 1999-2001. In this nationwide data set of whites, African Americans and Mexican Americans, the fact that TG was not a marker of insulin resistance was confirmed. However, TG was a marker of insulin resistance in whites and Mexican Americans. Again this demonstrates the need for ethnic specific guidelines. This work with NHANES was in press. To develop an index of free fatty acid sensitivity to insulin, we are working with mathematicians. The modeling is underway. The modeling of the influence of insulin on glucose levels was done in the nineteen eighties by Richard N. Bergman and colleagues. Because of the multiplicity of hormones that affect free fatty acid levels as well as the much wider range of biological variation in free fatty acids than glucose, achieving a model of the effect of insulin on free fatty acids is an even greater challenge. To achieve a model 150 participants in TARA have had frequently sampled intravenous glucose tests with glucose, insulin and free fatty acids levels determined at 36 timepoints in a 3 to 6 hour period. The complex multicompartment modeling is underway.