African-American women may have higher rates of type two diabetes because they are more likely to have been born at a lower weight, according to a new study from researchers at Boston University’s Slone Epidemiology Center.

African Americans are more likely than whites to be born at a low birth weight, a condition that may result in infant death or may have a lifelong effect on health. African American women are also at significantly increased risk of developing diabetes compared to white women. Rates of diabetes among white women were 5.4 percent in 2011, while rates for African American women were 9 percent.

African American women with low birth weight had a 13 percent chance of developing type two diabetes and those born at a very low weight had a 40 percent chance of developing the disease, according to the study, published in Diabetes Care last week. A weight of 2.5 kilos or about 5.5 pounds or less at birth was classified as low and a birth weight of 1.5 kilos or 3.3 pounds or less was considered very low.

African American women also have higher levels of obesity, which is a risk factor for diabetes, compared to white women. About 39 percent of African American women are obese compared to 21 percent of white women. Body mass index, however, did not appear to affect the relationship between low birth weight and diabetes.

“Women with low birth weight don’t have higher body mass indexes than women with normal birth weight, but they do have higher rates of type 2 diabetes,” explains Edward Ruiz-Narváez, assistant professor of epidemiology at Boston University.

Previous studies have connected low birth weight to higher rates of type 2 diabetes among African American women, but this study is unique because of its scale, Ruiz-Narváez says. The researchers used data from more than 21,000 women from Boston University’s Black Women’s Health Study, which has surveyed national participants every two years since 1995 on self-reported measures of health, including weight.