(VP013) ASSOCIATIONS OF MATERNAL GESTATIONAL DIABETES WITH OFFSPRING DIABETES ACROSS TWO PREGNANCIES: PRELIMINARY WORK

Background: Over 25% of children with type 1 diabetes (T1DM) in Quebec are diagnosed at the time of emergency presentation with diabetic ketoacidosis (DKA) (CJD, 2022). Knowledge of T1DM indicators may promote earlier detection. Our group identified a link between gestational diabetes (GDM) and pediatric diabetes (CMAJ, 2019). Whether this association comes from household/genetic factors or the intrauterine environment, is unknown. To gain insight into this issue, we are examining the associations of GDM during a sibling’s pregnancy with T1DM in the subject. We hypothesize that if household/genetic factors are responsible, having an exposed sibling could be a risk for T1DM in the subject, even in the absence of GDM during the index pregnancy.

METHODS AND RESULTS: Using public health insurance administrative databases from Quebec, we identified a cohort of 485,222 families with two consecutive deliveries from 1990 to 2012. Follow-up was until April 1st, 2019. We have calculated descriptive statistics and incidence rates (IR), for each of the following categories: (1) neither offspring was exposed to maternal GDM/diabetes; (2) only the sibling was exposed to GDM; (3) only the subject was exposed to GDM; (4) both offspring were exposed to GDM; (5) the mother had diabetes diagnosed prior to her first pregnancy. We conducted adjusted survival analysis and calculated hazards ratios (HR). A total of 2230 subjects developed diabetes before the end of the follow-up period. Diabetes IR was higher in all exposure categories compared to the control (2.71). Interestingly, IR for diabetes were similar for those exposed to GDM (3.83) and those whose sibling was exposed to GDM (3.63). Subjects directly exposed to GDM were at 39% higher risk than controls. Subjects who had a sibling exposed to GDM but who were not themselves exposed had an increase in risk of 32%. The risk was the highest when the mother had preexisitng diabetes, with a 6-fold increase in hazards.

Conclusion: These preliminary findings indicate that that IRs and HRs for diabetes were similar for those whose mother had GDM during pregnancy and those whose mother had GDM during a prior pregnancy. This suggests thathousehold/genetic factors may be more important than in utero glycemia in terms of contributions to offspring diabetes risk.