Protecting the guardians A guardian gene that protects against type 1 diabetes and other autoimmune diseases exerts its pancreas-shielding effects by altering the gut microbiota. Experiments in mice born with the protective gene show that exposure to antibiotics during critical windows of development fuels risk for type 1 diabetes and leads to loss of genetic protection by altering the gut microbiota. Scientists say the findings underscore the importance of avoiding antibiotic use during late pregnancy and early infancy.