Necrotizing fasciitis (NF) is a potentially fatal bacterial infection of the subcutaneous soft tissues. Two cases of polymicrobial NF in adolescents with type 1 diabetes mellitus and poor glycemic control are reported. The perineal region was involved in both cases. One case was precipitated by apparently minimal trauma, the other by high-impact trauma. Diabetes mellitus has been identified as a common comorbidity and predictor of increased mortality in adult patients with NF. The associations between diabetes and the incidence or outcome of NF in children and adolescents are not known. In all cases, early identification and aggressive surgical intervention are important for limiting morbidity and mortality.