An insulin pump is made up of a pump reservoir (like a insulin syringe, but bigger) filled with lispro insulin (humalog), a small battery-operated pump and a computer chip that allows the user to control exactly how much insulin the pump delivers. It is all contained in a plastic case about the size of a beeper.
The pump reservoir delivers insulin to the body by a thin plastic tube called an "infusion set". Infusion set have a needle or soft cannula at the end, through which the insulin passes. The needle or cannula is inserted under the skin, usually on the abdomen. The process of putting the infusion set in place is called "insertion", and is very much like giving a standard insulin injection. The infusion set is changed approximately every two to three days.
The pump is intended to be used continuously and delivers insulin 24 hours a day according to a programmed plan unique to each pump wearer. A small amount of insulin is given continually "basal rate". This insulin keeps blood glucose in the desired range between meals and over night. When food is eaten, the user programs the pump to deliver a "bolus doses" of insulin matched to the amount of food that will be consumed.
The pump is not automatic. The user still has to decide how much insulin will be given. But the pump is the most accurate, precise, and flexible insulin delivery system currently available. Using the results of blood glucose monitoring, the experienced pump user can use this tool to obtain excellent blood glucose control while living a normal lifestyle, free of the strict scheduling demands that are required by conventional insulin regimens.