A small, steady flow of insulin.
A significant advantage of an insulin pump is the ability to delivery a continuous flow of insulin into your body during the day and when you sleep. Insulin pump users typically set up a Basal Schedule that specifies which doses are applied during different times of the day.
Your body nearly always need a small amount of insulin to hold everything steady, even if you've not eaten food. On injections this is usually provided by the long-acting insulin. A pump gives you a small amount all the time, called the basal rate. You need to find out your own correct basal rate. See also bolus.