Early life Bacillus Calmette-Guerin vaccination and incidence of type 1, type 2, and latent autoimmune diabetes in adulthood

Abstract

AimsBacillus Calmette-Guerin (BCG) vaccination limits blood sugar elevations and autoimmunity. Previous studies focused on type 1 diabetes among children, despite possible effects on other phenotypes later in life. We studied associations between BCG vaccination and type 1, type 2 and latent autoimmune diabetes (LADA) in adulthood. MethodsA 1970–1974 birth cohort was linked with the BCG vaccination registry and administrative health data of Quebec. 396,118 people aged 22–44 years were followed-up for diabetes mellitus (DM) onset. Incident DM cases were subjects with ≥1 hospitalization or ≥2 physician claims related to DM over a 2-year period. Type 1 diabetes, type 2 diabetes, and LADA cases were individuals with ≥1 reimbursement of insulin, oral antidiabetic agent, or both. Cox proportional regressions were used to estimate hazard ratios (HR), adjusting for potential confounders. ResultsForty-four percent of subjects were BCG vaccinated, 88% of these before age 1. For type 1 diabetes, no association was found before 30 years old, but vaccinated subjects had a lower risk of this phenotype after age 30 (HRadj= 0.65, 95% CI: 0.44–0.95). BCG vaccination was associated with a lower risk of type 2 diabetes (HRadj=0.85, 95% CI: 0.79–0.92), whereas no association was observed for LADA (HRadj=1.30, 95% CI: 0.71–2.38). Results did not differ by sex. ConclusionsEarly life BCG vaccination was associated with lower risks of both type 1 and type 2 diabetes from early to middle adulthood, but not of LADA. Future studies should explore these long-term associations, while distinguishing diabetes phenotypes.