BackgroundDiabetic mastopathy is a rare breast condition that occurs in women with poorly controlled diabetes and is characterized by hardening of the breast tissue. The purpose of this case report is to provide an overview of the clinical characteristics and therapeutic principles of this rare disease to support front-line physicians in their crucial activity of case identification.Case presentationA 64-year-old Asian female patient with a history of type II diabetes mellitus was referred to our clinic for an evaluation of a newly discovered breast mass. The patient had been diagnosed with diabetes more than 20 years prior and was being managed with oral hypoglycemic agents. Her past medical history was otherwise unremarkable. Physical examination of the breast revealed a palpable, mobile, and firm mass measuring 6 × 4 cm in the upper quadrant of the right breast. Ultrasound images showed an uneven hypoechoic nodule, BI-RADS 4B. Mammography showed the compact and flaky nature of the two breasts and the heterogeneity of the substantive density increases. The patient’s clinical manifestations and imaging findings suggest the possibility of breast cancer. The patient opted for surgical excision of the mass. Through surgery, the mass was completely excised with negative margins. Pathological examination of the mass revealed a proliferation of fibroblastic cells, with an increased nuclear/cytoplasmic ratio, consistent with a diagnosis of diabetic mastopathy.ConclusionsThis case report serves to highlight the importance of recognizing diabetic mastopathy as a possible differential diagnosis of a breast mass in patients with diabetes mellitus. In our patient, early diagnosis and treatment with lumpectomy resulted in a favorable outcome, emphasizing the importance of prompt medical and surgical management. In addition, more research is needed to mine the diagnostic marker of diabetic mastopathy and provide data related to its prognosis.