May 2, 2000 -- Middle-aged African Americans are far more likely to develop adult-onset, or type 2, diabetes than middle-aged whites, with women much more likely than men to develop the disease, a study in this week's issue of the Journal of the American Medical Association reports.
The study also indicated that much of the extra risk in women may be due to controllable factors, particularly excess weight.
"One of the most important findings of our study is that the excess risk of developing diabetes in African American women is almost 50% due to adiposity [excess fat]," researcher Linda Kao, PhD, tells WebMD. "Clearly, this suggests that if that population could be targeted for prevention, we could reduce the incidence of type 2 diabetes substantially." Kao is a postdoctoral fellow in the department of epidemiology at Johns Hopkins University in Baltimore.
Type 2 diabetes, which is by far the most common type, typically begins after age 40. It occurs when the body can't make enough or properly use insulin, the hormone that maintains blood sugar levels. Often, it can be controlled by weight loss, improved nutrition, and exercise, though medications must sometimes be used. If not successfully managed, diabetes can lead to heart disease; stroke, eye and kidney problems; and problems involving the blood vessels, nerves, and feet.
Kao and colleagues used questionnaire and test results from about 12,000 participants in the Atherosclerosis Risk in Communities study, which has gathered data from more than 15,000 people living in four U.S. communities beginning in 1986.
"The profile of established risk factors for diabetes was clearly worse in African American women than in their white counterparts," the researchers write. "In particular, African American women had fewer years of formal education, were more likely to report a family history of diabetes, had greater measures of adiposity ... and reported less physical activity during leisure time." The racial difference in these risk factors, except for the difference in weight, was also seen in African American vs. white men.
According to the study, the risk of developing diabetes was about 2.4 times greater for African American women and about 1.5 times greater for African American men than for their white counterparts. The risk drops by almost half in African American women after the figures are adjusted to account for excess weight, but, Kao says, "the increased risk among African Americans still persists, indicating that some other factor, perhaps a genetic or environmental factor, or both, remains unidentified."
Helaine Resnick, PhD, a research fellow in the epidemiology, demography and biometry program at the National Institute on Aging of the National Institutes of Health, reviewed the study for WebMD. "I absolutely agree with this paper's conclusion that a lot of the risk of developing type 2 diabetes in this population is modifiable," she says.
Resnick says she believes that primary care doctors do not do enough to emphasize the dangers of diabetes. The condition, she says, is like high blood pressure in many ways: "It is not an acute condition and it isn't painful, so both patients and caregivers may not pay much attention to it, particularly when [other medical] conditions that are more acute exist.
"However, as we're seeing the population get much more overweight, and we're also seeing many more people living into their 70s and 80s, I believe we're going to see many more people with the manifestations of diabetes." Identifying the risk factors that can be changed and developing ways to intervene are crucial, she says.
- A new study shows that African Americans, especially women, are much more likely to develop type 2 diabetes than their white counterparts.
- Most of the difference can be explained by known risk factors, including obesity (among women only), family history of diabetes, fewer years of formal education, and less physical activity.
- Much of the risk for diabetes among the African American population can be modified with lifestyle changes, but a yet-unknown genetic or environmental factor may also contribute.