Progression From Gestational Diabetes Mellitus to Type 2 Diabetes Mellitus Among First Nations Women in Northwest Ontario: A Retrospective Cohort Study.

OBJECTIVE: Our aim in this study was to identify the incidence of type 2 diabetes mellitus among First Nations women in northwest Ontario with a history of gestational diabetes mellitus (GDM). METHODS: This work was a retrospective cohort study of women diagnosed with GDM using a 50-gram oral glucose challenge test or a 75-gram oral glucose tolerance test from January 1, 2010, to December 31, 2017, at the Sioux Lookout Meno Ya Win Health Centre. Outcomes were assessed based on glycated hemoglobin (A1C) measurements performed between January 1, 2010, and December 31, 2019. RESULTS: The cumulative incidence of T2DM among women with a history of GDM was 18% (42 of 237) at 2 years and 39% (76 of 194) at 6 years. Women with GDM who developed T2DM were of similar age and parity and had equivalent C-section rates (26%) compared to those who did not develop T2DM. They had higher birth weights (3,866 grams vs 3,600 grams, p=0.006) and rates of treatment with insulin (24% vs 5%, p<0.001) and metformin (16% vs 5%, p=0.005). CONCLUSIONS: GDM confers a significant risk for the development of T2DM in First Nations women. Broad community-based resources, food security, and social programming are required.