This report describes mandibular reconstruction using a 2-step bone transport technique in a cancer patient with type 2 diabetes mellitus (DM) who received radiotherapy before ablative surgery. The bone, measuring 90 mm in length with the mandibular curvature and good alveolar form, was regenerated using a plate-guided method. Three implants were placed 21 months after completion of the first distraction and 14 months after the second distraction. These implants integrated successfully and have remained stable more than 2 years after loading. The results suggest that mandibular reconstruction using bone transport is possible after segmental osteotomy in irradiated cancer patients with DM, although a long treatment period is required.