The patient was a 25-year-old woman whose paternal family was Japanese, maternal grandfather was Filipino, and maternal grandmother was Chinese. Eleven days after delivery, she presented with excessive thirst and disturbed consciousness due to diabetic ketoacidosis. She was diagnosed as having fulminant type 1 diabetes associated with pregnancy (PF). The antibody concentration against glutamic acid decarboxylase was 1.2 (<1.5) U/mL, and human leukocyte antigen (HLA) class II haplotypes were DRB1*04:10-DQB1*03:02 and DRB1*15:02-DQB1*05:01. The present case had unique HLA class II haplotypes that have not been previously reported in association with PF.