Hidden MODY in Young Lean Women with Mild Glucose Intolerance Detected during Health Check-ups: Potential for Improved Pregnancy Outcomes through Preconception Care

Mild glucose intolerance (positive urine glucose or mild hyperglycemia) during health checkups in young, lean women may require specialist consultation. We herein report a 31-year-old Japanese woman with mild hyperglycemia detected during a checkup who was diagnosed with overt diabetes in pregnancy and HNF4A-MODY postpartum, without prior follow-up. This case highlights the following: MODY may be present in young, lean women with mild glucose intolerance, and preconception care may improve pregnancy outcomes. Fetal outcomes vary with MODY subtype. Preconception care is important.