Insulin Pump: What It Is, How It Works, and Types

Aug 29, 2023

An insulin pump is a small wearable electronic device that helps regulate insulin and blood glucose (sugar) levels. Insulin is delivered from the pump through a thin plastic tube (catheter) and a small needle into the fatty tissue under the skin.

This article discusses what an insulin pump is, how it works, the different types of it that are available, and the advantages and disadvantages of using one.

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Some people with diabetes need to take insulin, a hormone that manages blood sugar levels. An insulin pump is a substitute for multiple daily needle injections of insulin.

An insulin pump administers insulin to the body through a thin plastic tube (catheter) and a small needle. It helps regulate insulin and blood glucose levels for people with diabetes. The small electronic device can be worn throughout the day and night.

Insulin pumps are programmed to deliver small amounts of rapid-acting insulin every few minutes, which acts as basal (baseline or "background") insulin. The basal insulin rate is set specifically for the person wearing and using the pump. This mimics insulin secretion similar to the body's normal regulation of insulin.

It can be adjusted for physical activity and keep blood glucose levels in a normal range. Insulin pumps can also be manually programmed to deliver a bolus (larger dose) of insulin as needed for high blood glucose corrections or if carbohydrates (sugars and starches) are consumed.

With a traditional insulin pump, a small, flexible tube called a catheter (also called a cannula) is inserted with the help of a tiny needle through the skin into the fatty tissue underneath. This is usually in the belly, hip, thigh, buttock, or upper arm.

The tubing connects to the pump, which can be worn on a waistband, on a belt, in a pouch, or in a pocket. Together, the tube and needle are called an infusion set.

When placed correctly, you shouldn't feel the catheter. You can go about your usual daily activities and go to sleep wearing it. Depending on the pump, you may even be able to wear it while bathing or swimming. The catheter typically stays in place for two to three days before you need to change it.

There are many advantages to using an insulin pump over injections. However, you should take certain factors into consideration before deciding if a pump is right for you.

The advantages of an insulin pump include:

The disadvantages of an insulin pump include:

Learning how to use an insulin pump and troubleshooting if there is a problem is of the utmost importance when using insulin pump therapy. Most diabetes care teams and insurance providers require you to check your blood glucose level a minimum of four times per day before starting on an insulin pump and to continue to do so while using a pump.

Monitoring your blood glucose frequently is important because it can prompt you if your pump isn't working or your infusion set malfunctions. This can prevent insulin from being delivered to the body and result in high blood glucose levels—leading to diabetic ketoacidosis (DKA).

DKA develops when your body doesn't have enough insulin to move glucose from the blood into your cells for use as energy. Instead, the liver breaks down fat for energy, which produces a byproduct called ketones. Having too many ketones in the body at once is very serious and life-threatening.

Checking blood glucose levels often throughout the day will help warn you of high blood glucose levels and prevent DKA.

Other daily safe pump habits include checking the tubing, ensuring there is enough insulin, and seeing that the battery is well charged.

Though the basic function of an insulin pump remains the same (delivering insulin), different features are offered depending on the brand and model you choose. In addition to traditional insulin pumps that have already been described, other types of pumps are available.

Patch insulin pumps do not use tubing. Instead, the patch contains the insulin reservoir and the infusion cannula and adheres directly to the skin. Patch pumps are programmed to deliver insulin through the infusion cannula from a remote device using wireless technology.

Sensor-augmented pumps (SAPs) combine an insulin pump and CGM in one system. In an SAP system, the insulin pump pairs with a CGM device and acts as the receiver. The CGM glucose sensor readings are then displayed on the pump's screen. This makes it easy to view glucose level information and plan insulin delivery on one device.

Closed-loop pumps are sometimes called "artificial pancreas" or automated insulin delivery systems. An automated insulin delivery system consists of an insulin pump and a CGM device. These two devices operate together with a control algorithm that actively calculates and adjusts insulin delivery based on the CGM glucose readings and trends, mimicking the job of the pancreas.

The first generation of automated insulin delivery systems is known as a hybrid closed-loop (HCL) system. HCLs actively adjust basal insulin delivery. However, users are still required to manually calculate and program bolus insulin doses for meals or correction doses.

A continuous glucose monitor or CGM is a wearable device that continuously measures glucose levels day and night. They are always on and measuring glucose levels—whether the user is working, exercising, showering, or sleeping. Many CGMs have alarms that will alert users whose glucose readings are too high or too low.

CGMs consist of three main parts:

CGMs allow for fewer daily fingersticks to check blood glucose levels, but they don't eliminate them. With most CGM models, you must first confirm a CGM glucose reading with a fingerstick blood glucose test before adjusting an insulin dose.

Insulin pumps can vary by the amount of insulin they hold and how you refill them—either with a prefilled cartridge or by hand. Some have carbohydrate calculators built in to help determine bolus doses. Others can connect to a blood glucose monitor or CGM, making it easier to manage blood glucose levels.

Additional features may include different types of alarms and alerts, the number of insulin delivery patterns available, and whether it is water resistant or waterproof. The size, weight, and color of the pump will also vary depending on the brand.

Talk with your diabetes care team and your insurance provider to help determine which pump will be best for you. They can let you know if there's a pump they recommend or prefer. In addition to telling you which pumps are covered, your insurance should also be able to give you an expected cost for the pump and supplies.

Ultimately, you will need to talk with your health insurance and diabetes care team to see if you are eligible for an insulin pump. However, below are some factors that may determine whether you're a good candidate for insulin pump therapy:

A member of your diabetes care team or a certified diabetes care and education specialist can train you to set up and use your insulin pump. They can also teach you how to check your blood glucose levels, set up and use a CGM, count carbohydrates, and make correction doses.

An insulin pump is a small electronic wearable device that administers insulin to the body through a thin plastic tube (catheter) and a small needle. It helps regulate insulin and blood glucose levels for people with diabetes and is used in place of insulin injections. Insulin pumps are worn on the outside of the body, usually on the hip, waist, or in a pocket or pouch.

There are several advantages to using an insulin pump, including less pain from multiple daily insulin injections, more flexibility with food and physical activity, and increased blood glucose control. Some disadvantages include the risk of infection, the risk of DKA, and the need for frequent blood glucose level checks.

Your diabetes care team can help you learn about the different types of pumps and pump features available, as well as teach you how to use the pump. Your care team and health insurance provider can help you determine if you are a good candidate for an insulin pump, tell you what brand is covered, and estimate the expected costs.

American Diabetes Association. Insulin pumps: relief and choice.

KidsHealth. What is an insulin pump?

American Diabetes Association. Who should use a pump.

Centers for Disease Control and Prevention. Diabetic ketoacidosis.

Berget C, Messer LH, Forlenza GP. A clinical overview of insulin pump therapy for the management of diabetes: past, present, and future of intensive therapy. Diabetes Spectr. 2019;32(3):194-204. doi:10.2337/ds18-0091

National Institute of Diabetes and Digestive and Kidney Diseases. Continuous glucose monitoring.

By Brittany Poulson, MDA, RDN, CD, CDCESBrittany Poulson, MDA, RDN, CDCES, is a registered dietitian and certified diabetes care and education specialist.