Insulin Pump Therapy

Pumps Basics

If you’re thinking about using a pump, you’ve probably got a lot of questions. This section will outline the basics of how a pump works.

An insulin pump is not implanted in your body. It’s a small, pager-sized device you wear or carry. It’s made up of a pump reservoir (like a regular syringe) filled with insulin; one or more small batteries, and a simple, programmable interface that allows you to control exactly how much insulin the pump delivers.

The pump reservoir delivers insulin to the body by a thin plastic tube ending in a soft plastic needle called a cannula, through which the insulin passes into your body. Some people choose to use steel cannulas rather than plastic ones, but the choice is yours. Together, this tubing and cannula are called an “infusion set.” You insert the cannula just under the skin, usually on the abdomen, thighs or buttocks using an introducer needle. You then remove the introducer needle, leaving only the cannula in place.

The process of putting the infusion set in place is called “insertion,” and is very much like giving an insulin shot — except you only do it every two to three days. Some infusion sets have an automatic insertion device to make it easier to insert the infusion set. Many people use a numbing cream such as ELA-Max to numb the skin before inserting. After vigorous exercise or swimming, you may need to replace an infusion set sooner than you normally would.

Basal and Bolus Insulin

The pump continuously delivers small amounts of background insulin, 24 hours a day, according to a plan that is unique to you. This insulin is called “basal insulin” and it keeps your blood sugar in the desired range between meals and overnight. When you eat, you program the pump to deliver a “bolus” dose of insulin matched to the amount of food, usually based on the carbohydrate content of the meal.

The pump is not fully automatic because you still have to decide how much insulin to give by closely monitoring your blood sugars (at least four to six blood sugar tests each day) and making adjustments when necessary. When you first go on the pump, your diabetes team will help you with this process. Then, all it takes is a few button presses to give yourself insulin rather than taking a shot.

Types of Insulin

Pumps only use rapid-acting insulin, which is the most predictable type of insulin. It takes effect within 10 to 20 minutes. If you go on an insulin pump, your doctor will prescribe either a regular or rapid-acting insulin analog (Humalog, NovoLog or buffered regular insulin). A recent study demonstrates that using Humalog instead of regular in a pump yielded better control and less hypoglycemia.