Gangrene in the head and neck region is very rare, but patients with diabetes mellitus or diseases that cause immune dysfunction may develop necrotizing fasciitis via dental maxillitis or other conditions. A 43-year-old man with untreated diabetes mellitus was urgently admitted to the hospital for dental maxillitis and ketoacidosis, and was referred for plastic surgery due to rapidly spreading gangrene on the right side of his face. Bacterial cultures were positive for Candida albicans and rapid debridement was impossible due to subsequent cerebellar hemorrhage and the presence of a brain abscess and pulmonary pyogenic disease. Fortunately, his general condition improved with conservative treatment and he returned to a normal life after more than 10 subsequent surgeries. Although the treatment requires a multidisciplinary team and early medical and surgical intervention, the timing of surgical intervention can be difficult due to unexpected complications or deterioration of a patient’s general condition.