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Insulin Delivery

What is a Pump?

By in Insulin Delivery

A pump is a small device that continuously provides both basal and meal time insulin through a small tube that is inserted under the skin. It pushes or “pumps” insulin into the body. Pumps use only rapid acting insulin.

Insulin pumps are not implanted into the body. The most common type has tubing that connects the pump to the body. These devices are the size of a pager and can be kept in your pocket or attached to your clothing by a clip. Every three days, a reservoir or cartridge is filled with insulin and attached to tubing that transports the insulin from the pump to the person wearing it. A small Teflon tube (or “cannula”) is inserted under the skin using a small needle that is immediately removed.

An alternative option is a “patch pump” or “pod” that doesn’t have tubing. The pod is filled with 200 units of insulin every 2-3 days, and applied to the body. This pump has a separate controller called a personalized diabetes manager, or PDM, that is used to calculate and deliver insulin doses.

Pump Vocabulary

Here are some terms that are common when pumping:

Basal Rate: Rapid acting insulin delivered continuously (every hour, 24 hrs/day) by the pump.

Bolus Calculator: Personalized settings used by the pump to determine insulin doses for meals, snacks and corrections doses. Insulin pumps do the math for you!

Cannula – small, hollow tube that sits under the skin. These come in different sizes, including 6 mm and 9 mm.

Carb Ratio: The number of carbohydrates covered per one unit of insulin.

Cartridges/reservoirs: Plastic container inside the pump (connected to tubing) that holds 200 to 300 units of insulin.

Correction Bolus: A larger amount of insulin delivered when blood glucose is high to bring it back to target range.

Meal Bolus: A larger amount of insulin used to cover carbohydrates eaten during a meal or snack.


Reviewed by Anastasia Albanese O’Neill, PhD, 7/15/19

This document is not intended to take the place of the care and attention of your personal physician or other professional medical services. Our aim is to promote active participation in your care and treatment by providing information and education. Questions about individual health concerns or specific treatment options should be discussed with your physician.


Benefits of Pumps

Pump Options

Hybrid Closed Loop