Baby mice that are given broad-spectrum antibiotics developed fewer beta cells in their pancreas and were more susceptible to developing Type 1 diabetes. Suppression of the intestinal fungus Candida dublinensis is associated with increased risk of diabetes, and supplementation with the fungus reduces the incidence of diabetes in mice genetically prone to diabetes.
Original paper: https://www.science.org/doi/10.1126/science.adn0953