For those with type 1 diabetes, multiple injections of insulin are required daily in order to maintain normal blood sugar levels. This strict regimen may also apply to certain patients with type 2 diabetes as well.

The primary methods of insulin injection are either manually by syringe or insulin pen, or automatically by insulin pump.

The multiple daily injection regimen via syringe or insulin pen is time consuming and can be disruptive to normal daily activities. For this reason, using an insulin pump to deliver insulin automatically and continuously can make daily insulin therapy easier and less intrusive.

The different methodologies for insulin delivery require different types of insulin. The two most common types of insulin available are rapid acting and long acting.  The former is generally taken before meals or when there is a spike in blood glucose levels, and the latter is taken to maintain glucose levels within normal range between meals, or over other long periods without eating, such as overnight.

Insulin injections via syringe or insulin pen uses both types of insulin, depending on the time of day and kind of activity; an insulin pump uses only rapid-acting insulin as it is continuously injecting insulin in small amounts to maintain healthy blood sugar levels.

Here is the information you need to understand how insulin pumps work, their advantages and disadvantages, and what kinds of insulin pumps are available to you right now.

What is an insulin pump

What is an insulin pump?

Insulin pumps are computerized instruments about the size of a pager which are designed to deliver insulin subcutaneously on a pre-programmed schedule. The insulin is delivered by a narrow tube or cannula that is placed just under the skin by a thin, short needle.

While the insulin pump itself is quite durable, certain components must be replaced every few days.  These include, of course, the insulin itself, the reservoir, tubing and the infusion set.

What are the basic parts of an insulin pump?

Insulin PumpThe Pump

Insulin pumps contain a set amount of insulin, the pumping mechanism, computer chip, battery and screen.  These are external pumps, worn outside the body, and connected to the infusion set by thin plastic tubing

These pumps can be worn attached to a belt, attached under one’s clothing by a strap, or by using an adhesive patch on the stomach or arm. They can also even be carried in a pocket.

The Infusion Set

The infusion set is the connection that enables insulin to flow into the skin from the pump.  A strong adhesive is used to attach it.  At the base of the infusion set is a short thin cannula or tube that pierces the skin and rests in the subcutaneous fatty tissue.

The Tubing

The tubing delivers insulin from the pump (insulin reservoir) to the infusion set

There is also a second type of insulin pump available: the tubeless pump, aka “the Pod”

In this tubeless system, a Pod filled with insulin is worn on the body, where the insulin can be injected, just as with the tubed pump.

The Pod contains an integrated infusion set that automatically inserts the cannula under the skin. Another piece of this tubeless system, the controller, controls the activity of the Pod. A major benefit of this system is that this controller only needs to be near the user to deliver a surge (“bolus”) amount of insulin, or to change infusion settings; it does not need to be attached to the user’s body.

However, the same general operating principles apply regarding how all pumps work, their advantages and disadvantages.

How does an insulin pump work?

Insulin is delivered by insulin pump either as small, continuous doses (basal insulin) throughout the day, or by surges near mealtimes (bolus insulin).

The use of an insulin pump still requires checking blood sugar levels at least four times a day. An easier alternative is to use a continuous glucose monitor (CGM) that will provide continuous glucose readings. More recently, automated systems have been developed that provide for continuous data feed from the CGM to the insulin pump to automatically adjust insulin doses.

The pump uses this information about food intake and blood sugar levels to calculate how much bolus insulin is needed. The pump then recommends a bolus dose to the user, and delivers it after approval. In addition, some pumps can automatically adjust the basal doses based on blood glucose levels transmitted from a continuous glucose monitor as well.

Defining the terms “basal” and “bolus” for insulin delivery

Basal Insulin

Basal insulin, also known as background insulin, is rapid acting insulin that is automatically and continuously delivered throughout the day in small controlled amounts by an insulin pump. It is delivered at a rate previously determined by the healthcare provider to keep glucose levels within the desired target range between meals and overnight. This timed delivery, known as the basal rate, eliminates the need for long-acting insulin.

An important benefit of insulin pump therapy is that the basal rate can be adjusted based on the user’s anticipated basal insulin needs. The user can then set different rates for different periods of the day when they may need more or less insulin.

Another benefit of the insulin pump is that the user can temporarily adjust their basal rate to deliver greater or lesser amounts of insulin for a short period of time. This is very helpful when exercising when a lesser amount of basal insulin might be needed, as well as for sick times, when a greater amount of basal insulin might be needed.

Bolus Insulin

Bolus insulin is the insulin delivered before eating or in response to an elevated blood glucose spike. The user can signal the insulin pump to deliver the bolus dose as needed. Depending on the design of the pump, the user can decide to take the bolus dose all at once or stretch all or part of it over a number of hours.

Advantages of using an insulin pump

  • Eliminates the need for regular injections with a syringe or insulin pen. A pump only requires one shot every few days when the infusion set is changed
  • A pump is more accurate than manual injections, enabling better management of blood sugar levels;  for example, fewer episodes of hypoglycemia and possible improvement of A1C levels
  • Helps manage the “dawn phenomenon” (early morning high blood sugar)
  • Capable of adjusting insulin rates based on the time of day, or planned activities such as exercise, sleep, or in cases of insulin resistance
  • Stores all dosing data, providing all the information needed for you and your healthcare providers to optimize the management of your diabetes
  • Modern pumps include a nutrition database to help determine carbohydrate intake, and a calculator to determine the insulin dose needed

NOTE: You should always need to have regular injectable insulin on hand in case the pump stops working.

Disadvantages of using an insulin pump

  • The need to enter information into the pump all day, and change out the infusion set every few days
  • The need for a commitment to follow the rules for safe usage, including checking blood sugar at least 4 times daily to make sure that the pump is working correctly. Otherwise, there is the risk of a life-threatening problem called diabetic ketoacidosis (DKA) due to uncontrolled high blood sugar.
  • The need for training on how to use the pump, which requires several visits with your healthcare team or a full day of outpatient training
  • Pump supplies can be expensive, and particular pumps may not be covered by your insurance
  • Possible issues include skin irritation, blockage of the cannula (insulin tube), or sites on the body that don’t absorb insulin adequately
  • The pumps can sometimes detach or get knocked off the body
  • Possible “device fatigue” where there is the feeling of burnout from the alerts and alarms

Currently available insulin pumps

This information is derived from “An Insulin Pump Guide from DiabetesMine” and updated for 2022.

Tandem Insulin Pump

Tandem t:slim X2

Tandem t:slim X2

The X2 is the latest version of this brand of touchscreen insulin pump from the California company Tandem Diabetes Care, which first introduced it back in 2012. The X2 has built-in Bluetooth connectivity, and it received FDA approval in 2016.

Tandem’s t:slim X2 is a tubed insulin pump with advanced features including a touchscreen and a newly designed cartridge for the insulin.  Instead of the traditional clear hard case inside reservoir, the insulin is stored in a flexible bag.

What also sets the t:slim X2 apart is the unique