New research suggests that women with a history of gestational diabetes are twice as likely to develop calcium in the heart arteries by mid-life even if healthy blood sugar levels were attained many years after pregnancy. In a press release, the authors of the study, published in Circulation, said this is a strong predictor of heart disease.

Gestational diabetes, defined as high blood sugar levels first recognized during pregnancy, affects approximately 9% of pregnancies in the United States and up to 20% worldwide. After pregnancy, women who had gestational diabetes are at higher risk of developing prediabetes or type 2 diabetes, both of which are risk factors for cardiovascular disease. 

“We were surprised to discover that women with a history of gestational diabetes are at a significantly greater risk of heart artery calcification, even if they maintain normal blood sugar levels after pregnancy,” said Erica P. Gunderson, PhD, MS, MPH, epidemiologist and senior research scientist in the Cardiovascular and Metabolic Conditions Section at Kaiser Permanente’s Division of Research in Oakland, California.

Earlier studies have found a much higher risk of heart disease in women with a history of gestational diabetes who later developed type 2 diabetes. However, investigators still do not know whether the risk of heart disease among women with a history of gestational diabetes was lower for those who attained healthy glucose levels or who developed prediabetes in mid-life.

The press release noted that in 2018, the American College of Cardiology/American Heart Association Cholesterol Clinical Practice Guidelines specified that a history of gestational diabetes enhances a woman’s risk for artery build-up leading to cardiovascular disease.

In the new study, researchers used data from the multicenter, 30-year prospective Coronary Artery Risk Development In Young Adult (CARDIA) study to investigate whether attaining healthy blood sugar levels after pregnancy would mitigate the increased risk of cardiovascular disease that is associated with a history of gestational diabetes. The CARDIA study enrolled more than 5100 men and women in the United States who were aged 18 to 30 years at the beginning of the study in 1985.

The new analysis includes approximately 1100 women without type 1 or type 2 diabetes who subsequently gave birth at least once during the 25-year study period, which ended in 2011. Blood tests were performed from before to after pregnancies at 5-year intervals to determine whether women had normal blood sugar levels, intermediate elevations in blood sugar levels, or whether they had developed overt type 2 diabetes. Heart scans were performed to measure coronary artery calcium at exams 15, 20, and 25 years after the baseline first exam of the study.

At the 25-year follow-up, the participants’ median age was 48 years old and 12% of the women had a pregnancy complicated by gestational diabetes. The prospective analysis found that women with a history of gestational diabetes had a 2-fold higher risk of coronary artery calcification whether they had healthy blood sugar levels, prediabetes, or type 2 diabetes.

Notably, attaining healthy blood sugar levels after pregnancy did not decrease the risk of developing cardiovascular disease in mid-life for women with a history of gestational diabetes. Of women with previous gestational diabetes, 36% developed prediabetes and 26% developed type 2 diabetes, compared to 35% and 9% of women with no history of gestational diabetes, respectively.

Furthermore, 25% of women with a history of gestational diabetes had some level of coronary artery calcium versus 15% of women who never had gestational diabetes.

“Risk assessment for heart disease should not wait until a woman has developed prediabetes or type 2 diabetes,” Gunderson said in a press release. “Diabetes and other health problems that develop during pregnancy serve as early harbingers of future chronic disease risk, particularly heart disease. Health care systems need to integrate the individual’s history of gestational diabetes into health records and monitor risk factors for heart disease, as well as the recommended testing for type 2 diabetes in these women at regular intervals, which is critical to target prevention efforts.”

Diabetes during pregnancy may increase risk of heart disease [news release]. American Heart Association; February 1, 2021. Accessed February 1, 2021.