Any injection or infusion which is given directly into a vein. The medical abbreviation for it is "IV." Insulin is given in this way when someone has a diabetic emergency, as it is the way to get the short-acting soluble insulin working at the most rapid rate. Using insulin in this manner brings with it a high risk of hypoglycemia once blood glucose levels begin returning to normal. Careful professional monitoring is necessary; this makes it a hospital or ER procedure for both people and pets.