Women typically don’t develop heart disease — or high blood pressure, one of its major risk factors — until after menopause. But “if you have diabetes, that rule no longer applies,” says Christine Maric-Bilkan, a program officer in the vascular biology and hypertension branch of the National Heart, Lung, and Blood Institute.

Diabetes “dramatically increases the risk” of heart disease at any age — overall, people with diabetes are twice as likely to have heart disease or a stroke as are other people — and its impact “tends to be greater in women than in men,” she says. Diabetes, a disease in which the body either doesn’t produce enough insulin (Type 1) or cannot use it properly (Type 2), can cause spikes in blood sugar. Over time, these spikes can damage nerves and blood vessels, putting diabetics at elevated risk of heart disease and stroke.

Uncontrolled diabetes also contributes to vision loss, kidney failure and amputations, according to the National Institute of Diabetes and Digestive and Kidney Diseases.

People with diabetes are up to four times as likely to develop cardiovascular disease as are people who do not have diabetes, according to the Cleveland Clinic. Women with diabetes are twice as likely to suffer a second heart attack and four times as likely to suffer heart failure as are women who do not have the disease, according to the American Diabetes Association.

“The risk of developing hypertension doubles in men and quadruples in women if you have diabetes,” Maric-Bilkan says. (Hypertension is a major contributor to heart disease.)

“There is something about diabetes that takes away the protective factor” against heart disease that premenopausal women seem to have, something probably related to estrogen, she says. “Women are not impacted by heart disease as much as men at younger ages, but once they have diabetes, that protection is lost — and diabetes has an overall greater impact on women, compared with men, at all ages.”

In 2011, Maric-Bilkan tested a small group of premenopausal Finnish women with Type 1 diabetes and found that they all had lower-than-normal estrogen levels.

“I don’t know if they got diabetes because their estrogen levels were reduced, or the reverse,” she says. “One thought is that it’s the estrogen that gives protection, but men with diabetes, who also have a greater risk of heart disease, have high estrogen and low testosterone, the opposite of women. So the high estrogen doesn’t protect men. Diabetic women have more testosterone than non-diabetic women, so it may have to do with the balance of hormones.”

She stresses that the risk of death from heart disease “is exceptionally high in women with early-onset [Type 1] diabetes compared with women in the general population,” according to a study she authored.

“Women with diabetes need to understand that the risk of getting heart disease is significant, and they need to be aware of it,” she says.