(Ivanhoe Newswire) -- Mild glucose intolerance in pregnancy may be an early identifier of women who are at increased risk of heart disease in the future, according to a new Canadian study. As cardiovascular disease is the leading cause of death in Canadian women, it is important to identify early predictors of future vascular risk.

While women with gestational diabetes have a higher risk of cardiovascular disease than those without, researchers did not know whether mild glucose intolerance in pregnancy is associated with heart disease. The study sought to answer this question.

In a large population-based cohort study, researchers from the University of Toronto and the Institute for Clinical Evaluative Sciences (ICES) studied data on 435,696 women in Ontario, Canada, who gave birth between April, 1994 and March, 1998. All women were followed until March 31, 2008. The study excluded women with pre-existing diabetes.

Gestational diabetes is a condition leading to temporarily high blood sugars during pregnancy and is an important risk factor for future type 2 diabetes. Generally women are screened for gestational diabetes with a glucose challenge test in the late second trimester. If the result is abnormal, they go on to have an oral glucose tolerance test to confirm the diagnosis.

"Women who had an abnormal glucose challenge test but then did not have gestational diabetes had an increased risk of future cardiovascular disease compared to the general population, but a lower risk than women who actually did have gestational diabetes," Dr. Baiju Shah, Institute for Clinical and Evaluative Sciences and coauthor wrote.

The study authors suggested that "in women with glucose intolerance during pregnancy, type 2 diabetes and vascular disease may develop in parallel, which is consistent with the "common soil" hypothesis for these conditions."

In a related commentary, Dr. J. Kennedy Cruickshank and Dr. Moulinath Banerjee of the Manchester Royal Infirmary, University of Manchester, U.K. wrote, "What the study by Retnakaran and Shah shows is that we all have a great deal to learn from sub-clinical blood vessel changes in younger women who are likely overweight during pregnancy."