Hi, Thanks for the query. I understand your concern. The oral cavity is loaded with protective & helpful bacteria Lacto bacilli when the bacilli get destroyed by conditions like bad oral hygiene, dry mouth, infection, medication like steroids antibiotics, bowel infections, uncontrolled diabetes, HIV, cancer.. the bacteria or fungi in oral cavity supervene & the infection starts. Diabetic medicines do not cause yeast infection but uncontrolled diabetes favors the infection. She should get through medical check up to exclude or find the causes for the yeast infection in your body, get diabetic control with proper medicines/ improve eating habits & digestion . You need not be stressed... when cause of infection is found , the condition can be treated with treatment of basic cause & local or oral anti fungal medicines. Thanks.