Phyllodes tumors are rare fibroepithelial neoplasms that account for less than 1% of all breast tumors and are typically found in middle-aged women. Phyllodes tumors that present with hypoglycemia are even rarer. No one morphologic finding is reliable in predicting the clinical behavior of this tumor. Surgery has been the primary mode of treatment to date. However, the extent of resection and the role of adjuvant radiotherapy or chemotherapy are still controversial. Here, we present a challenging case of malignant phyllodes tumor of the breast associated with hypoglycemia, and review the literature regarding clinical findings, pathologic risk factors for recurrence, and treatment recommendations.