Provided herein are compositions and methods for the treatment of type 1 diabetes (T1D) in mammalian subjects. The compositions include lactic acid fermenting bacteria (LAB) expressing an IL-2 gene and a T1D-specific self-antigen (e.g., proinsulin (PINS)) gene. Exemplary methods include: orally administering to a mammalian subject, a therapeutically effective amount of the composition. The composition can be administered to the subject mucosally, resulting in delivery of the LAB into the gastrointestinal tract, where the LAB is released. Bioactive polypeptides expressed by the LAB are thus administered via mucosal delivery. The LAB may be selected to deliver a low-dose of IL-2 to the subject. The methods may not require concomitant systemic anti-CD3 antibody treatment. The methods may be suited for subjects possessing residual beta-cell function, e.g., those with recent-onset T1D.