Diabetes is a chronic disease that develops when the body does not produce enough insulin or cannot effectively use the insulin it produces. Diabetics have abnormally high blood sugar levels, which if left untreated can lead to serious health problems, including foot ulcers, blindness, kidney failure, heart disease and stroke.

Jean Lawrence studies diabetes at Kaiser Permanente, a large health care organization. She looked at the medical records of a racially and ethnically diverse group of women in southern California who became pregnant between 1999 and 2005. "We studied about 175,000 teenage and adult women," says Lawrence, "and examined whether or not they had diabetes before pregnancy, or whether they developed gestational diabetes during their pregnancy." Gestational diabetes is usually a temporary condition that goes away after a mother gives birth.

The researchers found that the proportion of women who developed gestational diabetes remained relatively constant throughout the study period, at about seven and half percent. But, Lawrence notes, the proportion of women who had diabetes before they became pregnant doubled over the course of the study, reaching almost two percent.

"The increase we see was observed in all of the racial and ethnic groups." But Lawrence qualifies that African American women in the study had the highest prevalence of diabetes before pregnancy, followed by Hispanic women, then Asian and Pacific Islander women, and then Caucasian women. "It's not surprising that African Americans seem to have the highest burden of diabetes prior to pregnancy, because they also have a very high burden of diabetes in general in the population," she explains.

Lawrence emphasizes that more young women of all races are entering their reproductive years with diabetes, especially what's known as Type 2 diabetes. Usually caused by lifestyle factors such as poor diet, obesity and a lack of exercise, it used to develop mostly in adulthood and in fact was called "adult onset" diabetes.

"But now what we're seeing is that youth are developing Type 2 diabetes as young as age ten." Lawrence attributes the change to an increased prevalence of obesity in children, and in people of all ages in the general population.

Lawrence stresses that women should work with a doctor to control their diabetes before becoming pregnant. High blood sugar early in pregnancy can result in miscarriage, stillbirths and birth defects.

"As we know in the U.S., about half the pregnancies are unplanned or unintended," says Lawrence. "So the take home message is that it's really important for all women to plan their pregnancies." But in this case, she stresses, "It's exponentially important for women with diabetes to plan their pregnancies so that they can work on making sure their diabetes is in good control and they are healthy before becoming pregnant."

Her findings are available in the May issue of Diabetes Care.