E p i d e m i o I o g y / H e a 11 h S e r v i c e s / P s y c h o s o c i a I Researc NAL A R T I C L E The Impact of Socioeconomic Status Cardiovascular Risk Factors in African-Americans at High Risk for Type II Diabetes Implications for syndrome X TRUDY R. GAILLARD, RN, MS, CDE DARA E SCHUSTER, MD BRENDA M. BOSSETTI, RD, CDE, PHD PATRICIA A. GREEN, RD, CDE KWAME OSEI, MD OBJECTIVE — The rate of type II diabetes in African-Americans is reaching epidemic pro- portions. African-Americans with type II diabetes suffer from more cardiovascular diseases (CVDs) associated with diabetes than the general population. Lower socioeconomic status (SES) and family history are often cited as contributory factors to the premature development of diabetes and CVDs in the general population. However, we are not aware of any study that has examined the relationships between SES and CVD risk factors (i.e., syndrome X) in a genet- ically enriched African-American population at high risk for type II diabetes. RESEARCH DESIGN AND METHODS— We studied 200 healthy first-degree rela- tives of African-American patients with type II diabetes (age 25-65 years, mean 42.5 ± 8.4 years; 42 men, 158 women). Standard oral glucose tolerance test, metabolic, and anthropo- metric parameters, as well as questionnaires on SES, demographic characteristics, and physi- cal activity, were obtained for each subject. SES was divided into quartiles based on annual income. To assess the impact of insulin on CVD risk, we examined clinical characteristics and metabolic parameters according to quartiles of fasting insulin concentrations. RESULTS — Clinical characteristics, including mean age, BMI, waist-to-hip ratio (WHR), per- centage body fat and lean body mass, and blood pressure were not statistically different among SES quartiles. There were no significant differences in any of the metabolic, blood pressure, lipid and lipoprotein, or anthropometric parameters among SES quartiles. When examined by insulin quartile, BMI, WHR, and body fat content tended to be greatest in the fourth quartile. Similarly, fasting and postprandial serum C-peptide and glucose levels were significantly higher in the fourth quartile. We observed greater levels of very low density lipoprotein (VLDL) cho- lesterol and triglycerides and lower levels of HDL cholesterol in the fourth compared with the first through third insulin quartiles. Serum cholesterol and LDL cholesterol were not associated with increasing insulin concentration assessed by quartiles. We found similar systolic and dias- tolic blood pressure, irrespective of insulin quartiles. We found relationships between fasting insulin and systolic blood pressure (r = 0.181, P < 0.05) and triglycerides (r = 0.247, P < 0.01), VLDL cholesterol (r = 0.237, P < 0.01), WHR (r = 0.268, P < 0.005), BMI (r = 0.308, P < 0.001), and percentage of body fat (r = 0.237, P < 0.01). CONCLUSIONS — The present study demonstrates no SES/income effect on CVDriskfac- tors or syndrome X in African-Americans at high risk for type II diabetes. Clustering of several components of syndrome X was seen in individuals in the highest quartiles compared with the lowest quartiles of insulin in our high-risk African-American population. We conclude that the well-established conventional risk factors for CVD in genetically enriched African-Americans are found only in individuals with the highest insulin levels, independent of SES. From the Division of Endocrinology, Diabetes and Metabolism, The Ohio State University, Columbus, Ohio. Address correspondence and reprint requests to Kwame Osei, MD, Professor of Medicine, Director, Division of Endocrinology, Diabetes and Metabolism, 485 McCampbell Hall, 1581 Dodd Drive, Columbus, OH 43210. Received for publication 15 July 1996 and accepted in revised form 19 December 1996. BP, blood pressure; CVD, cardiovascular disease; NHANES II, National Health and Nutrition Examina- tion Survey II; SES, socioeconomic status; VLDL, very low density lipoprotein; WHR, waist-to-hip ratio. C ardiovascular diseases (CVDs; e.g., heart attacks, strokes) are the leading cause of death in the Western world, including the United States (1,2). The mor- bidity associated with CVDs results in enor- mous economic cost and human suffering. Several risk factors have been associated with the development of CVDs, including family history of CVDs, diabetes, hyperlipi- demia, hypertension, smoking, and obesity (2-5). The constellation of these metabolic factors and hypertension has been termed syndrome X, or insulin resistance/hyperin- sulinemia metabolic syndrome (6-9). According to the Framingham study (4,5), diabetic populations are associated with a two- to fourfold increased risk for coronary artery disease, myocardial infarction, and stroke when compared with nondiabetic populations. Increased CVD in diabetic patients has been ascribed partly to lipid and lipoprotein abnormalities (quantitative and qualitative), hypercoagulability etc. Characteristically, type II diabetic patients have lower HDL cholesterol, normal serum cholesterol, and high triglyceride levels (4,5,10). These changes have been impli- cated in the accelerated atherosclerosis found in patients with type II diabetes. There are racial and ethnic differences in the components of CVD risk factors (11-13) and type II diabetes is associated with an accelerated rate of development of CVDs in African-Americans, particularly women (4,5,8,9,11). Although the reasons for these racial and ethnic discrepancies are not known, the higher prevalence rates of obesity and hypertension in African- American females have been implicated as possible explanations (1-3,10-14). In addition, abnormalities in lipids and lipoproteins are associated with the etiology of coronary artery disease in several popu- lations (4,5,8,9). Ironically, in African- Americans with and without diabetes, serum HDL cholesterol levels tend to be much higher, whereas triglyceride levels DIABETES CARE, VOLUME 20, NUMBER 5, MAY 1997 745