Women with gestational diabetes at risk of type 2 diabetes

Women with gestational diabetes are at greater risk of developing type 2 diabetes, with almost 20% of women developing the condition within 9 years of pregnancy, found a large, population-based study of 659,000 women published in CMAJ. The study, http://www.cmaj.ca/press/pg229.pdf, conducted by a group of researchers from the University of Toronto, Mount Sinai Hospital and the Institute for Clinical and Evaluative Sciences, looked at 21,823 women diagnosed with gestational diabetes and examined follow up records up to 9 years. They found the rate of diabetes increased rapidly in the first 9 months after delivery, peaking at 9 years.

"In this large, population-based study, we found that diabetes developed within 9 years after the index pregnancy in 18.9% of women with previous gestational diabetes; this rate was much higher than the rate among women without gestational diabetes (2%)," state Dr. Denice Feig and coauthors.

As well, they note that the rate of gestational diabetes in Ontario, the study province, seems to be increasing and is linked to older mothers. Living in low-income neighbourhoods and in urban areas were also risk factors for gestational diabetes. Higher urban statistics "may reflect the large numbers of South and East Asian and black populations living in urban areas, who have a higher risk of type 2 diabetes," postulate Dr. Feig and colleagues.

"The main strength of our study lies in the fact that it was a large population-based study involving more than 21,000 women with gestational diabetes, with up to 9 years of follow-up," state the researchers. "Unlike other studies, it covered a large, well-defined geographic region with a population of 13 million, which allowed us to make a more robust assessment of the risk of type 2 diabetes after gestational diabetes than has been possible in previous studies."

However, the study could not "assess the effect of ethnicity, obesity and level of fasting glucose during pregnancy, risk factors that are clearly associated with the development of diabetes."

"These women may benefit from both preventative interventions and regular screening," conclude the researchers who point out that physicians and policy makers need to counsel and screen these women accordingly.

In a related commentary, Dr. David Simmons of Cambridge University Hospitals NHS Foundation in the UK (James Woodman, james.woodman@addenbrookes.nhs.uk, for Dr. David Simmons) comments that many women with gestational diabetes become pregnant again, leading to potential risks for the fetus. "Type 2 diabetes in pregnancy, particularly if previously undiagnosed, is associated with poor outcomes, including an increased incidence of fetal loss, malformation and perinatal death." He argues for more investment in prevention and screening programs for at-risk women to protect women and their future children.

Source: Canadian Medical Association Journal