Diabetes Care, Vol 20, Issue 5 745-752, Copyright © 1997 by American Diabetes Association
The impact of socioeconomic status on cardiovascular risk factors in African-Americans at high risk for type II diabetes. Implications for syndrome X
TR Gaillard, DP Schuster, BM Bossetti, PA Green and K Osei
Division of Endocrinology, Diabetes and Metabolism, Ohio State University, Columbus 43210, USA.
OBJECTIVE: The rate of type II diabetes in African-Americans is reaching
epidemic proportions. 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 genetically enriched African-American
population at high risk for type II diabetes. RESEARCH DESIGN AND METHODS:
We studied 200 healthy first-degree relatives 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
anthropometric parameters, as well as questionnaires on SES, demographic
characteristics, and physical 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), percentage 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)
cholesterol 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
diastolic 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
CVD risk factors 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.