Diabetic mastopathy is an uncommon condition found in patients with long-standing diabetic mellitus (DM). Although benign in nature, it can sometimes not be distinguishable from breast carcinoma, and may lead to unnecessary anxiety or intervention. Clinicopathologic features of 10 patients were reviewed in detail. Only three of the 10 patients had type I DM. All patients had over a 10-year history of DM, and presented with unilateral, solitary, palpable breast mass, ranging in size from 1.5 to 5 cm. Radiologic and pathologic features of each patient were described. None of the patients in our series developed malignancy during the follow-up period. Diabetic mastopathy is a benign condition and not unique to type I DM. Surgeons should be aware of this distinct fibroinflammatory breast condition and its association with long-standing DM.