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Insulin Pump How-To

How does a pump work?

By Gary Scheiner, MS CDE

One kind of insulin pump is a beeper-sized device that contain a cartridge filled with fast-acting insulin. They have a screen and buttons for programming the pump's internal computer, and a sensitive motor that turns very gradually to push insulin from the cartridge through a tube and into your body. The tubing that connects the pump to your body comes in various lengths and is very strong.

To get the insulin under your skin, an infusion set is worn. Most infusion sets use a needle (about the size of an insulin syringe needle) to insert a small, flexible plastic tube just under the skin, usually on the abdomen, buttocks, or hip. The needle is then removed and the infusion set is taped securely in place. A new infusion set is inserted every 2 to 4 days, depending on individual usage. Many infusion sets feature a "quick disconnect" mechanism that allows the user to temporarily unhook the pump and tubing for situations like bathing, contact sports, and intimacy.

The pump itself is usually worn on a belt/waistband or in a pocket. A variety of clips, cases, and fashion accessories make the pump easy to wear in just about any situation. Today's pumps also have multiple safety features that ensure against accidental insulin delivery – even under the most severe or unusual conditions.

The other kind of insulin pump is placed directly on the body, there is no tubing, and a needle is inserted where the pump is attached. This kind of pump, called a patch pump, is controlled by a PDA.

All insulin pumps run multiple safety checks every second and have sensitive alarm systems. Insulin delivery is not usually affected by electro-magnetic fields, pressure changes, temperature extremes or physical impact (although the insulin contained in the pump can be harmed by extreme conditions). Because the pumps "lock up" and alarm in the event of any internal problem, there is virtually no chance of accidental insulin delivery.