Trends in Gestational Diabetes Screening Practices in British Columbia from 2005-2019

To examine trends in the frequency and method (one-step vs. two-step) of gestational diabetes mellitus (GDM) screening in British Columbia (BC), Canada, across subgroups of pregnant individuals in the context of changing local and national clinical practice guidelines.

We conducted a retrospective cohort study using de-identified, linked perinatal and laboratory billing data. We included all pregnancies delivered in BC after 28 weeks gestation, with screening dates between June 2004 and May 2019. We calculated the prevalence of each screening method with 95% CI overall and over time, and we examined screening practices in subgroups and different geographic regions. In October 2010, BC began recommending a one-step method; therefore, we examined time periods relative to this and other Canadian guideline changes.

Screening completion increased over the study period, from 88% in 2004 to 96% in 2019. After a guideline change in 2010, use of one-step screening increased sharply from 2.0% (95% CI 1.9-2.0) to 45.2% (95% CI 44.9-45.6). Following the 2013 Diabetes Canada guideline change, one-step screening decreased to 42.8% (95% CI 42.5-43.1). Of those receiving one-step screening, 18% were diagnosed with GDM compared to 9% with two-step screening. Use of one-step screening was higher in pregnant people with risk factors and in larger urban centres.

GDM screening in BC demonstrated higher use of one-step screening among people with risk factors; however, there were strong regional disparities and considerable variation in screening practices over time and across subgroups.