Diabetes and Heart Disease Risk in Blacks

黑人的糖尿病和心脏病风险

• 批准号: 9356113
• 负责人: Anne Sumner
• 金额: $ 95.56万
• 依托单位: NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/9356113
• 关键词: Adverse effects; Affect; Africa; African; African American; Age Factors; Agreement; American; Americas; Area; Asian Indian; Asians; Birth; Body Size; Body fat; Body mass index; Cardiac health; Cardiovascular Diseases; Cardiovascular system; Chinese People; Cholesterol; Collaborations; Country; Data; Data Set; Detection; Development; Diabetes Mellitus; Diagnosis; Diagnostic; Diagnostic Sensitivity; Diagnostic tests; Disease; Early Diagnosis; Early Intervention; Education; Educational Status; Environment; Epidemiology; Ethnic Origin; Fasting; Fructosamine; Ghana; Goals; Guidelines; Health; Heart Diseases; Height; Hemoglobin; Hemoglobin C; High Density Lipoproteins; High Prevalence; Hypertension; Immigrant; Immigration; Income; Institutes; Insulin Resistance; Intervention; Investigation; Japanese Population; Life; Lipids; Measures; Methods; Mexican Americans; National Health and Nutrition Examination Survey; Nigeria; OGTT; Obesity; Osteoporosis; Outcome; Parents; Participant; Physicians; Physiology; Population; Prediabetes syndrome; Prevalence; Preventive Intervention; Process; Protocols documentation; Public Health; Reporting; Research; Risk; Risk Factors; Role; Running; Sampling; Sickle Cell Trait; South African; Stress; Testing; Therapeutic; Time; Triglycerides; United States; Validation; Variant; Vitamin D; Vitamin D supplementation; Weight; Woman; Women' s Group; Work; allostatic load; bone health; cardiometabolic risk; cardiovascular risk factor; cohort; diabetes risk; diabetic; efficacy testing; fasting glucose; glycosylated serum albumin; health disparity; heart disease risk; improved; mathematical methods; men; non-smoker; prevent; programs; racial difference; screening; tool; trait; waist circumference

This protocol compares diabetes and heart disease risk in African-Americans (AA) and African immigrants. The AA cohort is known as TARA for: Triglyceride and Cardiovascular Risk in AA. The African immigrants are known as the: Africans in America cohort. The sample of AA participating appears to be representative of the AA population of the United States because the prevalence of obesity (43%), pre-diabetes (22%) and hypertension (21%) is similar to National Health and Nutrition Examination Survey data. However, there is no national data on diabetic or cardiac health of African immigrants. Therefore we are working to establish basic information. To explore risk for diabetes, we are relying not just on fasting glucose but are also on performing oral glucose tolerance tests and measuring A1C levels, fructosamine and glycated albumin levels. In performing these tests, we discovered that the prevalence of pre-diabetes and hypertension is twice as high in African than AA men. In addition, the rate of undiagnosed diabetes was 7% in African men vs. 0% in AA men. In contrast the rate of hypertension, diabetes and pre-diabetes are similar in African women and AA women. Identifying the reasons for why African immigrant men are less metabolically healthy than AA men has become a major focus of research in this protocol. To improve and then maintain good health in African men, it is essential to understand why pre-diabetes, diabetes and hypertension is occurring in African men even though African men are less obese, more likely to be non-smokers, more likely to be married and have similar educational levels and income as African-American men. As a next step we are now examining the effect of stress of immigration on diabetic and cardiovascular risk in African immigrants. We are measuring stress with the Allostatic Load Score. The specific immigration related factors we are age of immigration, duration of stay in the United States and reason for immigration. We are also working on determining whether A1C which has been recommended by the American Diabetes Association as a diagnostic test for diabetes, can replace the oral glucose tolerance test in people of African descent. A1C is a hemoglobin dependent test and African immigrants have a high prevalence of sickle cell trait (i.e. 10 to 40%) and hemoglobin C trait (i.e. 15% in West Africa). Therefore before widespread use of A1C as a diagnostic test for diabetes is instituted in Africa, validation is necessary. When we evaluated A1C in African immigrants, we found that the sensitivity was 50%. When the Africans are subdivided by presence or absence of variant hemoglobin, the sensitivity of A1C remained at 50%. Therefore, A1C is not be an ideal, single test in Africans and variant hemoglobins such as sickle cell trait and hemoglobin C trait are not the explanation for the low diagnostic efficacy of A1C. To achieve better diagnostic efficacy, we are in the process of examining alternatives such as fructosamine and glycated albumin as single tests and in combination with A1C. We have found that fasting glucose combined with A1C has a diagnostic sensitivity of 70%. But since obtaining a fasting sample can be problematic, we have also tested the combination of fructosamine and A1C and glycated albumin and A1C. Importantly we have found that in the detection of diabetes and prediabetes in Africans immigrants the combination of fructosamine and A1C is no better than A1C alone. However, the combination of A1C and glycated albumin had a diagnostic sensitivity of 72%. This is a big step forward because glycated albumin, while not yet widely available, is an inexpensive and easy test to set up and run. We are now working on establishing collaborations with physicians in several African countries to directly evaluate the efficacy of A1C and glycated albumn in Africa. The relationship of body size to cardiovascular and diabetes risk is another area of investigation. In our cohorts, the mean body mass index (BMI) in AA is 30.6 kg/m2 but only 26.4 kg/m2 in African immigrants. BMI is a mathematical method used to correct weight for height. Due to the broad range of BMI in the participants in this cohort, it is possible to evaluate the relationship of body size to insulin resistance, a major factor in the development of diabetes, and heart disease. We have found in AA men a waist circumference (WC) of 102 cm predicts both insulin resistance and obesity. This is in agreement with the National Cholesterol Education Program values for whites. But in African men, insulin resistance occurs at a much lower WC, specifically 92 cm. This difference between AA and African immigrant men, suggests that a single WC of risk does not apply to all African descent populations. The situation may be analogous to Asian populations, as the WC of risk is different in Chinese, Japanese and Asian Indians. In AA women we found that a WC of 98 cm predicted both insulin resistance and obesity and this WC of risk was similar in AA, African immigrant, Black South African and West African women. Therefore among populations of African descent, there may be less variation in women than men. However, as the WC of risk is 88 cm in white women, there is a large difference by race. Guidelines which screen for disease might be more effective if this was better appreciated and more fully understood. 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 AA. Results from TARA were so impressive that the hypothesis that TG was not a marker of insulin resistance in African Americans was subsequently tested in NHANES data collected from 1999-2001. In this NHANES data set of whites, AA and Mexican Americans, the fact that TG was not a marker of insulin resistance was confirmed. However, TG was a powerful marker of insulin resistance in whites and Mexican Americans. Altogether this research on race differences in the relationship of TG to insulin resistance again demonstrates that to detect disease at time when intervention can affect outcome, there is a need to develop ethnic-specific guidelines. Recently the TG/HDL ratio at a level of >3.0 has been suggested to be a marker of insulin resistance. This is well established in whites. After demonstrating the TG/HDL ration did not work in AA, we tested the ratio in white South African women, Black South African women and West African women from Ghana and Nigeria. We found that while the ratio effectively predicted insulin resistance in the white women, it did not work in any group of women of African descent. Again demonstrating that findings related to insulin resistance in whites may not be applicable globally and systematic testing is necessary. Recently, it has been reported that low vitamin D levels may influence bone health as well as enhance risk for cardiometabolic disease. As people of African descent have lower vitamin D levels than whites, the adverse effect of low vitamin D in people of African descent may be magnified. Alternatively vitamin D may be sufficient at lower levels in people of African descent than whites. We have discovered that 50% of African immigrants have low vitamin D levels but less than 10% had evidence of deficiency. As vitamin D has a relatively narrow therapeutic whether it is wise to provide vitamin D supplementation to large numbers of African immigrants with vitamin D levels defined as low but no evidence of deficiency remains to be determined. In summary this protocol is dedicated to undertaking epidemiological research which defines relevant risk factors, improves cardiometabolic health, and prevents through early diagnosis, diabetes and heart disease in people of African descent globally.

该方案比较了非裔美国人（AA）和非洲移民的糖尿病和心脏病风险。 AA队列被称为TARA：AA中的甘油三酸酯和心血管风险。非洲移民被称为：美国队列中的非洲人。 AA参与的样本似乎代表了美国的AA人群，因为肥胖症的患病率（43％），糖尿病前期（22％）和高血压（21％）与国家健康和营养检查调查数据相似。 但是，没有关于非洲移民的糖尿病或心脏健康数据的国家数据。因此，我们正在努力建立基本信息。为了探索糖尿病的风险，我们不仅依赖禁食葡萄糖，而且还依靠口服葡萄糖耐受性测试并测量A1C水平，果糖胺和糖化白蛋白水平。在进行这些测试时，我们发现糖尿病前和高血压的患病率在非洲男性中高是非洲男性的两倍。此外，非洲男性的未诊断糖尿病发生率为7％，而在AA男性中为0％。相比之下，非洲妇女和AA妇女的高血压率，糖尿病和糖尿病前期相似。确定为什么非洲移民男性在代谢上比AA男性不那么健康的原因已成为该协议中的研究重点。为了改善非洲男性的健康状况，必须了解为什么非洲男性糖尿病，糖尿病和高血压会发生，即使非洲男人不太肥胖，更有可能是非吸烟者，更有可能结婚，并且与非洲美洲男性具有类似的教育水平和收入。 作为下一步，我们现在正在研究非洲移民对糖尿病和心血管风险的压力的影响。我们正在用同层负载得分来测量应力。我们的特定移民与移民年龄，在美国的住院持续时间和移民的原因。 我们还在努力确定美国糖尿病协会推荐的A1C是否作为糖尿病的诊断测试，可以取代非洲血统患者的口服葡萄糖耐受性测试。 A1C是血红蛋白依赖性测试，非洲移民的镰状细胞性状患病率很高（即10至40％）和血红蛋白C特征（即15％在西非）。因此，在非洲进行了广泛使用A1C作为糖尿病的诊断测试之前，有必要进行验证。当我们评估非洲移民的A1C时，我们发现灵敏度为50％。当非洲人通过存在或不存在变异血红蛋白细分时，A1C的敏感性保持在50％。因此，在非洲人中，A1c不是理想的单个测试，而变异性血红蛋白（例如镰状细胞性状和血红蛋白C性状）并不是A1C诊断功效低的解释。为了获得更好的诊断功效，我们正在研究替代果糖胺和糖化白蛋白等替代方法作为单个测试，并与A1C结合使用。我们发现，禁食葡萄糖与A1C结合的诊断灵敏度为70％。但是，由于获得禁食样本可能是有问题的，因此我们还测试了果糖，A1C和A1C和糖化白蛋白和A1C的组合。重要的是，我们发现，在检测非洲移民的糖尿病和糖尿病前期，果糖和A1C的组合仅比A1C更好。但是，A1C和糖化白蛋白的组合的诊断敏感性为72％。这是向前迈出的一大步，因为糖化的白蛋白虽然尚未广泛可用，但它是一个便宜且易于设置和运行的测试。我们现在正在努力与多个非洲国家的医生建立合作，以直接评估非洲A1C和糖化or糖化的疗效。 身体大小与心血管和糖尿病风险的关系是另一个研究领域。在我们的队列中，AA中的平均体重指数（BMI）为30.6 kg/m2，但在非洲移民中仅为26.4 kg/m2。 BMI是一种用于纠正高度重量的数学方法。由于该队列参与者的BMI范围广泛，因此可以评估体型与胰岛素抵抗的关系，糖尿病发展的主要因素和心脏病。我们在AA男子中发现了102 cm的腰围（WC）预测胰岛素抵抗和肥胖。这与白人国家胆固醇教育计划的价值观一致。但是在非洲男性中，胰岛素抵抗发生在低得多的WC，特别是92厘米。 AA和非洲移民男子之间的这种差异表明，单一的风险WC不适用于所有非洲血统人群。这种情况可能类似于亚洲人群，因为中国，日本和亚洲印第安人的风险WC有所不同。 在AA妇女中，我们发现98厘米的WC预测了胰岛素抵抗和肥胖症，而这种风险的WC在AA，非洲移民，南非黑人和西非妇女中相似。因此，在非洲血统的人群中，女性的变化可能比男性少。但是，由于白人妇女的风险为88厘米，因此种族有很大的差异。如果更好地理解并且更充分理解，哪种疾病筛选的准则可能会更有效。 升高的TG和低HDL被认为是胰岛素抵抗的脂质标志。但是，尽管TG升高是白人胰岛素抵抗的标志，但我们已经表明TG不是AA中胰岛素耐药性的标志。塔拉（Tara）的结果令人印象深刻，以至于在1999 - 2001年收集的NHANES数据中测试了TG不是非裔美国人胰岛素抵抗标志的假设。在NHANES数据集，AA和墨西哥裔美国人的数据集中，TG并不是胰岛素抵抗的标志。但是，TG是白人和墨西哥裔美国人胰岛素抵抗的有力标志。总之，这项关于TG与胰岛素抵抗关系关系种族差异的研究再次表明，在干预会影响预后时发现疾病，需要制定特定民族的准则。最近，已经建议在> 3.0的水平上的TG/HDL比是胰岛素抵抗的标志。这在白人中已经很好。在证明了TG/HDL定量在AA中不起作用后，我们测试了南非妇女，南非黑人妇女和来自加纳和尼日利亚的西非妇女的比例。我们发现，尽管该比率有效地预测了白人妇女的胰岛素抵抗，但它在任何非洲血统的妇女中都没有起作用。再次证明与白人胰岛素耐药性有关的发现可能不适用于全球，并且必须进行系统的测试。 最近，据报道，低维生素D水平可能影响骨骼健康，并增加心脏代谢疾病的风险。由于非洲血统的维生素D水平低于白人，因此低维生素D对非洲血统的不利影响可能会受到放大。或者，在非洲血统的人群中，维生素D在较低的水平上比白人足够。我们发现，50％的非洲移民的维生素D水平较低，但少于10％的移民有缺陷的证据。由于维生素D是否具有相对较窄的治疗方法，无论是否为大量的非洲移民提供维生素D的维生素D水平，其维生素D水平定义为低，但没有缺乏症状的证据。 总而言之，该方案致力于进行流行病学研究，以定义相关的危险因素，改善心脏代谢健康，并通过早期诊断，糖尿病和心脏病来防止全球非洲血统。