Gestational diabetes, or diabetes diagnosed for the first time during pregnancy, is a common condition, affecting approximately one in 25 pregnant women in Canada. After the baby is born, women who had gestational diabetes may be eager to leave their blood sugar concerns behind, but beware: women who have had gestational diabetes are at high risk of developing type 2 diabetes.

In pregnancy, there are several factors that contribute to the development of gestational diabetes, including increased food intake, weight gain, decreased exercise, and the production of several hormones by the placenta that make the mother more resistant to the effects of insulin. As the development of gestational diabetes identifies women whose pancreas is not able to keep up in the face of the stress of pregnancy, it also identifies women who are at future risk of developing full blown type 2 diabetes (outside of pregnancy). In fact, having had gestational diabetes increased the risk of developing type 2 diabetes later in life by up to 12 fold.  Further, some cases of gestational diabetes were likely type 2 diabetics before the pregnancy started, but they did not come to medical attention until the pregnancy began.

Because the impact of undiagnosed type 2 diabetes postpartum is of serious consequence to the mother’s health, and also has implications for future childbearing, it is essential that these women undergo screening for type 2 diabetes postpartum. Blood sugars will be checked following delivery in the hospital, but this alone is not enough, as diabetes can return after discharge home when normal life and eating patterns resume.

All women who have had gestational diabetes must undergo a glucose tolerance test within 6 weeks to 6 months postpartum. This involves drinking a glucose containing drink, with measurement of blood sugar before and 2 hours after the drink is taken. Checking fasting blood sugars is not enough, as this will miss 40% of type 2 diabetes in the postpartum population.

Additionally, women with previous gestational diabetes must be screened for type 2 diabetes:

  • before any future pregnancies
  • every 3 years, or more often, depending on other risk factors

Unfortunately, as few as 25% of women who have had gestational diabetes complete this important postpartum testing. Having undiagnosed type 2 diabetes can cause injury to blood vessels supplying vital organs including the heart, kidneys, and eyes. Having undiagnosed type 2 diabetes at the time of the next pregnancy can have devastating consequences to the fetus, including congenital malformations and miscarriage.

If you have or have had gestational diabetes, speak to your doctor to be sure that you have undergone, and continue to undergo, the appropriate screening.

Dr Sue Pedersen © 2010

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