1184-P: No Increased Risk of Gestational Diabetes Mellitus (GDM) Diagnosis after COVID-19 Vaccination

Background: Hyperglycemia and possible accelerated onset of de novo diabetes have been reported following COVID-19 vaccination in nonpregnant adults. The objective of this study was to examine the risk of GDM after COVID-19 vaccination in pregnancy. Methods: Using data from 8 integrated health care systems participating in the Vaccine Safety Datalink, we performed a retrospective analysis among 42,140 pregnancies resulting in livebirth from 1/27/21 -1/25/22. Diagnosis of GDM was defined as two outpatient or one inpatient ICD-10 codes for GDM at or beyond 22 weeks’ gestation. GDM diagnoses were compared between individuals who received one or two COVID-19 vaccine doses prior to 22 weeks’ gestation and those who did not receive a COVID-19 vaccine during pregnancy. We used generalized estimating equations with robust variance and inverse probability weighting to estimate the adjusted relative risk (aRR) and 95% Confidence Interval (CI) of GDM, accounting for baseline differences between vaccinated and unvaccinated individuals. Results: Of the 42,140 pregnancies, 38% identified as Hispanic, 33% non-Hispanic White, 15.6% non-Hispanic Asian, 8.8% non-Hispanic Black, and 4.4% other or unknown; 25.6% received one or more COVID-19 vaccine doses prior to 22 weeks’ gestation. Individuals who were vaccinated were older (mean age 32.0 ± 4.6 vs 29.5 ± 5.3 years) and more likely to be of non-Hispanic White (37.4% vs 31.7%) or Asian background (25.7% vs 12.1%) than those who were unvaccinated. The rate of GDM was 11.9 per 100 among those who received a COVID-19 vaccine and 10.6 per 100 among those who did not. There was no increased risk of GDM diagnosis associated with receipt of a COVID-19 vaccine during pregnancy, aRR 1.00 (95% CI 0.90-1.10). Conclusion: Data from this large cohort did not identify an increased risk of GDM associated with receipt of a COVID-19 vaccine prior to 22 weeks’ gestation. These results further support emerging evidence regarding the safety of COVID-19 vaccination in pregnancy.