Trends in Gestational Diabetes in Manitoba From 1981 to 2019: A Descriptive Study With Geospatial Mapping.

Objective: This study aimed to describe trends in incidence of gestational diabetes in Manitoba and within subgroups that often experience health inequities.

Methods: We leveraged provincial administrative health data to describe trends in gestational diabetes incidence between 1981 and 2019, stratified by subpopulations based on age, urbanicity, and neighbourhood-level average household income. We calculated yearly incidence across subgroups and annual percent change in incidence to assess trends over time. Geospatial mapping was used to visualize changes by neighbourhood cluster.

Results: Gestational diabetes incidence increased from 1.3% to 8.6% between 1981 and 2019, with an upward inflection occurring around 2010. The annual percent change (APC) between 1981 and 2009, prior to the inflection point, was 1.9% (95% confidence interval [CI] 1.4% to 2.5%) and was 11.7% (95% CI 8.9% to 14.7%) postinflection---from 2010 to 2019. After 2010, gestational diabetes incidence increased most among urban residents (APC 18.1%, 95% CI 13.9% to 22.5%), among those >35 years of age (APC 12.0%, 95% CI 8.4% to 15.7%), and among individuals in the highest socioeconomic status (SES) group (APC 14.8%, 95% CI 9.4% to 20.4%). Geospatial mapping showed that incidence increased more in neighbourhoods with the highest proportion of recent immigrants to Canada.

Conclusions: Incidence of gestational diabetes increased 6-fold in Manitoba over the past 20 years, particularly among those with high SES and higher age. Further research is required to clarify the role of screening practices in the trends observed in this work.