Self-monitoring of blood glucose (SMBG) is an integral component in the management of diabetes. However, it is important to understand the limitations of SMBG due to presence of interfering substances (1). We present a patient with diabetes and malignancy, who had falsely elevated blood glucose readings following administration of intravenous ascorbic acid (AA). A 56-year-old woman with type 1 diabetes was diagnosed with metastatic pancreatic neuroendocrine tumor. She administered insulin glargine and insulin aspart before meals. After three cycles of chemotherapy, due to poor response, she decided to stop further traditional therapies. She consulted a naturopath, who started her on intravenous AA at a dose of 75 g twice weekly. Following this, she noted that her SMBG levels were consistently elevated after intravenous …