Diabetic mastopathy (DMP) is a benign fibrous disease of the breast. DMP is closely associated with along-standing history of insulin-dependent diabetes mellitus and often demonstrates a palpable, hard, and nontender mass similar to breast cancer. In our study, excisional biopsy was performed for diagnosis in both patients. DMP is an uncommon benign fibrous disease of the breast that is difficult to differentiate from breast cancer by clinical examination. Breast ultrasonography and mammography are recommended. Core biopsy should be performed if the lesions become clinically or radiologically suspicious. Excisional biopsy should be performed if malignancy cannot be excluded. Regarding mastectomy, we think that the patient's preference is very important; physicians can never make decisions for patients no matter how certain we are about nonmalignancy.