Since our previous work (4, 5, 19) showed that treatment of adult mice with β-glucan is effective in altering the gut microbiota composition leading to improved immune regulation and disease outcomes in T1D and colitis, we examined if oral administration of β-glucan at juvenile age, which involves changing/maturing gut microbiota, impacted the composition and function of microbiota and the eventual T1D onset. Here, PPIB is linked to type 1 diabetes mellitus.