An insulin pump is a medical device used for the administration of insulin in the treatment of diabetes mellitus, also known as continuous subcutaneous insulin infusion therapy. The device includes:

• the pump itself (including controls, processing module, and batteries)
• a disposable reservoir for insulin (inside the pump)
• a disposable infusion set, including a cannula for subcutaneous insertion (under the skin) and a tubing system to interface the insulin reservoir to the cannula.

An insulin pump is an alternative to multiple daily injections of insulin by insulin syringe or an insulin pen and allows for intensive insulin therapy when used in conjunction with blood glucose monitoring and carb counting.

Setting up

In order to use an insulin pump, the reservoir must first be filled with insulin. Some pumps are designed to be used with prefilled cartridges that are replaced when empty. Most, however, must be filled with insulin of the user's choice (usually Novolog, Humalog, or Apidra). Setting up includes:

1. Opening a new (sterile) empty pump reservoir of the manufacturer's design;
2. Withdrawing the plunger;
3. Inserting the needle into a vial of insulin;
4. Injecting the air from the reservoir into the vial to prevent a vacuum forming in the vial as insulin is withdrawn;
5. Drawing insulin into the reservoir with the plunger, and then removing the needle;
6. Squirting out any air bubbles from the reservoir, and then removing the plunger;
7. Attaching the reservoir to the infusion set tubing;
8. Installing the assembly into the pump and priming the tubing (pushing insulin and any air bubbles through the tubing) - it is essential that this is done with the pump disconnected from the body to prevent accidental insulin delivery;
9. Attaching to the infusion "site" (and priming the cannula if a new set has been inserted).

Dosing

An insulin pump allows the replacement of slow-acting insulin for basal needs with a continuous infusion of rapid-acting insulin.

The insulin pump delivers a single type of fast-acting insulin in two ways:

• a bolus dose that is pumped to cover food eaten or to correct a high blood glucose level.
• a basal dose that is pumped continuously at an adjustable basal rate to deliver insulin needed between meals and at night.

Bolus Shaping

An insulin pump user has the ability to influence the profile of the rapid-acting insulin by shaping the bolus. While each user must experiment with bolus shapes to determine what is best for any given food, they can improve control of blood sugar by adapting the bolus shape to their needs.