Streptozotocin is approved by the U.S. Food and Drug Administration (FDA) for treating metastatic cancer of the pancreatic islet cells. Since it carries a substantial risk of toxicity and rarely cures the cancer, its use is generally limited to patients whose cancer cannot be removed by surgery. In these patients, streptozotocin can reduce the tumor size and reduce symptoms (especially hypoglycemia due to excessive insulin secretion by insulinomas).^[1] A typical dose is 500 mg/m²/day by intravenous injection, for 5 days, repeated every 4-6 weeks.

Due to its high toxicity to beta cells, in scientific researches, streptozotocin has also been long used for inducing insulitis and diabetes on experimental animals.^[2]