Kaiser Permanente research shows 2-fold higher risk for heart artery calcification after pregnancy through mid-life, even in women with normal blood sugar levels
By Sue Rochman
Women with a history of gestational diabetes are at increased risk for heart artery calcification, a marker of increased risk for heart disease, throughout their childbearing years and into mid-life, even if they currently have normal blood sugar levels, new Kaiser Permanente research shows.
The prospective study, published in Circulation, is the first to look at heart disease risk in relation to changes in blood sugar levels in women who developed gestational diabetes and those who did not over a 25-year period. The study found a 2-fold higher risk for heart artery calcification in women who had gestational diabetes and normal blood sugar compared with women who did not have gestational diabetes and had normal blood sugar levels. The 2-fold higher risk was present in women with a history of gestational diabetes who many years later had blood sugar levels classified as normal, pre-diabetes, or type 2 diabetes.
“We expected that women who had developed diabetes during pregnancy and then had attained normal blood sugar levels in the 15 years after pregnancy would have a lower relative risk of heart artery calcification than those who later developed prediabetes or type 2 diabetes,” said Erica P. Gunderson, PhD, MS, MPH, senior research scientist in lifecourse cardiovascular and metabolic research at the Kaiser Permanente Northern California Division of Research, who led the study. “Our findings represent a paradigm shift by showing that normal blood glucose many years after gestational diabetes is associated with the same higher risk of heart artery calcification also seen in women who have developed prediabetes or type 2 diabetes.”
Each year in the U.S., about 250,000 pregnant women develop diabetes. The disease develops when the body can’t properly turn food into the glucose, or sugar, it needs for energy because the pancreas isn’t making enough insulin or the body isn’t using insulin properly. When this happens, sugar is unable to get into the body’s cells, and sugar levels increase in the blood. Overtime, metabolic factors and inflammation can damage blood vessels and the nerves that control the heart, increasing risk for heart disease.
The new study analyzed data collected on 1,133 women enrolled in the Coronary Artery Risk Development in Young Adult Study (CARDIA), a 25-year prospective study that began enrolling Black and white adults ages 18 to 30 in Birmingham, Chicago, Minneapolis, and Oakland in 1985. All study participants were given a computed tomography (CT) scan to measure heart artery calcification and a glucose tolerance test to check blood sugar levels before pregnancy and up to 5 times during the 25 years of follow-up. Of the 1,133 women studied, 139 developed gestational diabetes. Over the next 25 years, the CT scans found calcification in 25% of the women who had gestational diabetes and 15% of the women who did not.
“In women, adverse pregnancy outcomes like gestational diabetes serve as early harbingers of future risk for chronic diseases, including heart disease,” said Gunderson. “Individual risk assessment for early signs of heart disease is important for women with a history of gestational diabetes during the childbearing years through midlife, long before they develop high blood sugar or type 2 diabetes.”
Because gestational diabetes greatly increases a woman’s lifelong risk for type 2 diabetes, the American Diabetes Association currently recommends all women who develop gestational diabetes have a glucose tolerance test every 1 to 3 years. American Heart Association guidelines underscore that a history of gestational diabetes is important to consider in evaluating individual risk for atherosclerotic heart disease.
The new findings suggest physicians should monitor clinical risk factors for heart disease in all women who develop gestational diabetes before they develop prediabetes or diabetes. Women with a history of gestational diabetes may also benefit from healthy lifestyle choices and weight loss to reach ideal body weight. “Pregnancy complicated by gestational diabetes is a harbinger of future cardiovascular disease in women,” said Gunderson. “The study findings add to the growing body of evidence that suggests women with a history of gestational diabetes may have increased risk of heart artery calcification, even if they do not have prediabetes or type 2 diabetes or other known risk factors for heart disease.”
The study was funded by the National Institute of Diabetes and Digestive and Kidney Diseases.
Co-authors include Baiyang Sun, MPH, and Janet M. Catov, PhD, of the University of Pittsburgh; Mercedes Carnethon, PhD, Norinna B. Allen, PhD, and Lifang Hou, PhD, of Northwestern University; Cora E. Lewis, MD, MSPH, of the University of Alabama at Birmingham; Stephen Sidney, MD, MPH, and Jamal S. Rana, MD, PhD, of the Division of Research; and Melissa Wellons, MD, and John Jeffrey Carr, MD, MSCE, of Vanderbilt University.
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About the Kaiser Permanente Division of Research
The Kaiser Permanente Division of Research conducts, publishes and disseminates epidemiologic and health services research to improve the health and medical care of Kaiser Permanente members and society at large. It seeks to understand the determinants of illness and well-being, and to improve the quality and cost-effectiveness of health care. Currently, DOR’s 600-plus staff is working on more than 450 epidemiological and health services research projects. For more information, visit divisionofresearch.kaiserpermanente.org or follow us @KPDOR.