A nine-year study of more than 12,000 middle-aged Americans suggests that at least half the extra risk for diabetes faced by African American women is linked to relatively simple and modifiable lifestyle factors. The same was not true for African American men, according to the study team led by Johns Hopkins investigators.
"We've known for a long time that compared to their white counterparts, middle-aged African Americans have both higher blood pressure and a higher prevalence of Type 2, noninsulin-dependent diabetes and its complications," says Frederick L. Brancati, lead author of the study and associate professor of medicine and epidemiology. "But this study suggests that poor diet, high blood pressure, body fat and lack of exercise are accountable for nearly half the risk in women."
Results of the government-funded epidemiological study, published in the May 3 issue of The Journal of the American Medical Association, show that African American women are 2.4 times more likely to develop diabetes and African American men are 1.5 times more likely to develop diabetes than whites. Pre-diabetes high blood pressure also is more frequent among African Americans than whites.
"On the basis of these findings, we urge patients, especially those with high blood pressure, to adopt a more healthy lifestyle and urge physicians to more aggressively lower high blood pressure before diabetes develops," Brancati said.
As part of a long-term, ongoing study called Atherosclerosis Risk in Communities, researchers analyzed nationwide data on 12,107 adults ages 45 to 64 who either had heart disease or were at risk for developing it. None had diabetes when the participants first underwent extensive health evaluations between 1986 and 1989. Annual telephone interviews and clinic visits every three years were completed. After nine years, researchers looked at the status of such potentially modifiable risk factors as body-mass index, physical activity, smoking, alcohol use and diet as well as other predisposing biological factors like blood pressure and plasma lipids.
In all, 1,425 patients (459 African Americans and 966 whites) developed diabetes. Among the 6,763 women, 25 percent of African Americans (298 people) developed diabetes, compared with 10.4 percent of whites (425 people). Among the 5,344 men, 23 percent of African Americans (161 people) developed diabetes, compared with 15.9 percent of whites (541 people).
African American women had fewer years of formal education, were more likely to have a family history of diabetes, had greater measures of body fat and reported less physical activity during leisure time. But potentially modifiable risk factors, such as diet and body fat, accounted for 47.8 percent of the excess risk of diabetes, Brancati says.
While similar risk factors were found in men, they did not account for racial differences in risk.
The study was supported by the National Heart, Lung and Blood Institute, the American Diabetes Association and the American Heart Association. Other Hopkins authors were W.H. Linda Kao and Moyses Szlko.