Diazoxide, sold under the brand name Proglycem among others, is a medication used to treat low blood sugar due to a number of specific causes. This includes islet cell tumors that cannot be removed and leucine sensitivity. It can also be used in refractory cases of sulfonylurea toxicity. It is taken by mouth.

Diazoxide, used as the salt diazoxide choline, and sold under the brand name Vykat XR, is used for the treatment of hyperphagia in people with Prader–Willi syndrome. It was approved for this use in the United States in March 2025.

Common side effects include high blood sugar, fluid retention, low blood platelets, a fast heart rate, increased hair growth, and nausea. Other severe side effects include pulmonary hypertension and heart failure. It is chemically similar to thiazide diuretics. It works by decreasing insulin release from the pancreas and increasing glucose release by the liver.

Diazoxide was approved for medical use in the United States in 1973. It is on the World Health Organization's List of Essential Medicines. It is available as a generic medication.

Diazoxide is used as a vasodilator in the treatment of acute hypertension or malignant hypertension.

Diazoxide also inhibits the secretion of insulin by opening ATP-sensitive potassium channel of beta cells of the pancreas; thus, it is used to counter hypoglycemia in disease states such as insulinoma (a tumor producing insulin) or congenital hyperinsulinism.

Diazoxide acts as a positive allosteric modulator of the AMPA and kainate receptors, suggesting potential application as a cognitive enhancer.

Diazoxide interferes with insulin release through its action on potassium channels. Diazoxide is one of the most potent openers of the K+ ATP channels present on the insulin producing beta cells of the pancreas. Opening these channels leads to hyperpolarization of cell membrane, a decrease in calcium influx, and a subsequently reduced release of insulin.