Gestational diabetes raises risk of type 2 diabetes

By Anne Harding

NEW YORK (Reuters Health) - Developing diabetes while pregnant -- what doctors call gestational diabetes -- greatly increases a woman's risk of developing type 2 diabetes later on, a new study confirms.

"Because of the high level of risk for these women, both screening for type 2 diabetes and preventive measures should be taken," Dr. Denice Feig of the University of Toronto, who was involved in the study, told Reuters Health.

Detecting and treating type 2 diabetes is particularly crucial if a woman plans to become pregnant again, she added, because poorly controlled diabetes in pregnancy increases the risk of fetal malformations and stillbirth.

Gestational diabetes is a known risk factor for type 2 diabetes. To gauge the exact degree of risk, Feig's team looked at 633,449 women who gave birth in Toronto between 1995 and 2002. A total of 21,823 (3.3 percent) of the women were diagnosed with gestational diabetes.

While just 2 percent of the women who didn't have gestational diabetes went on to develop type 2 diabetes during the 9-year follow-up period, 19 percent of those with gestational diabetes did, the researchers found.

Moreover, they say the strongest risk factor for type 2 diabetes was gestational diabetes, which increased risk more than 37-fold.

Women who are diagnosed with gestational diabetes can help ward off type 2 diabetes by staying at a healthy weight and exercising, Feig noted. Taking these steps can also help to reduce the risk of developing gestational diabetes, the researcher added, but some factors in the development of diabetes in pregnancy aren't modifiable, such as a person's family history of diabetes.

SOURCE: CMAJ: Canadian Medical Association Journal, July 29, 2008.