Generally, women under 60 are at far less risk for coronary artery disease than men of the same age. But among women of that age who have diabetes, their risk of heart disease increases by up to four times, making it roughly equal to men's risk of this same form of heart disease.

"Our findings suggest that we need to work harder to prevent heart disease in women under 60 who have diabetes," says Rita Rastogi Kalyani, M.D., M.H.S., endocrinologist at the Johns Hopkins University School of Medicine and lead study author. "This study tells us that women of any age who have diabetes are at a high risk for coronary artery disease."

While men generally have a higher incidence of heart disease than women, the study found that diabetes had little or no effect on men's heart disease risk.

Kalyani said the new study is believed to be the first to focus specifically on gender differences in coronary artery disease among younger and middle-aged people with diabetes.

For the research, she and her colleagues analyzed data from more than 10,000 participants in three widely regarded studies: the GeneSTAR Research Program, the Multi-Ethnic Study of Atherosclerosis and the National Health and Nutrition Examination Survey (NHANES) III. None of the participants had a history of heart disease. All three studies yielded similar gender differences in rates of diabetes and the risk of developing heart disease.

"Our study adds to growing evidence that gender differences exist in the risk of coronary artery disease brought on by diabetes," Kalyani says.

Interestingly, in both women and men, these findings were unrelated to differences in obesity and other traditional cardiovascular risk factors such as high blood pressure, cholesterol and smoking.

Kalyani and her colleagues offer several possible explanations for the increased risk. There may be distinct genetic and hormonal factors related to the development of heart disease by gender. Differences in adherence to heart-healthy lifestyle behaviors, compliance and treatment of cardiovascular treatments between genders are also possible but need to be further investigated, Kalyani says. Also, the relationship of diabetes duration and glucose control to risk of heart disease remains unclear.