Postpartum Diabetes Testing Rates after Gestational Diabetes Mellitus in Canadian Women: A Population-Based Study

We assessed the rate and type of postpartum glycemic testing in women with impaired glucose tolerance of pregnancy (IGTp) and gestational diabetes mellitus (GDM). We examined whether the likelihood of testing was modulated by patients' characteristics and pregnancy outcomes.

Our population-level cohort study included data from 132,905 pregnancies between October 1, 2008, and December 31, 2011, in Alberta, Canada. Laboratory data within 270 days before and 1 year after delivery were used to identify pregnancies involving IGTp/GDM and postpartum glycemic testing, respectively. Logistic regression was used to identify maternal and pregnancy factors associated with postpartum testing.

A total of 8,703 pregnancies were affected by IGTp (n=3669) or GDM (n=5034) as defined by the prevailing Canadian Diabetes Association 2008 Clinical Practice Guidelines for the Prevention and Management of Diabetes in Canada. By 1 year postpartum, 55.1% had undergone glycemic assessments. Of those, 59.7% had had 75 g oral glucose tolerance tests, 17.4% had had glycated hemoglobin tests without oral glucose tolerance tests and 22.9% had had only fasting or random glucose tests. Women with IGTp or GDM, respectively, who were younger, smokers and residing in rural areas and whose labours were not induced were less likely to be tested postpartum. Having large for gestational age infants was also associated with a lower likelihood of postpartum testing in women with GDM.

Despite a universal health-care system in Canada, many women with IGTp or GDM do not undergo postpartum glucose testing. Maternal and pregnancy characteristics influence postpartum testing and provide valuable information for creating targeted strategies to improve postpartum testing in this group of high-risk women.