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Insulin Pump Basics

Insulin Pump Basics

1. What is an insulin pump? 

a. Computerized insulin delivery device 

b. Delivers insulin similar to the natural pancreas 

Technology has opened a new area IN diabetes management.  Devices such as blood glucose meters, continuous glucose monitors, and insulin pumps have helped to simplify diabetes management to achieve better outcomes in diabetes care.  

Insulin pump therapy is one part of this wave of new technology that has been widely used in diabetes management.   Insulin pumps deliver rapid acting insulin in a manner that closely mimics the natural insulin delivery by the pancreas. Some insulin pumps are connected to a continuous glucose monitor that controls the release of insulin in your body and utilizing specialized algorithms and artificial intelligence).  

Compared to insulin injections, insulin pumps can deliver insulin doses in smaller amounts with more flexibility in dosing that can be tailored to the needs of the individual. 

2. What are the parts of an insulin pump? 

a. Pump 

b. Reservoir 

c. Tubing  

d. Canula 

e. Insulin  

f. Some pumps are connected to & communicate with sensors /CGMS – adjusts insulin flow  

The insulin pump itself is a small, computerized insulin delivery device that uses only rapidacting insulin.  The reservoir is the part of the insulin pump that contains the insulin for delivery.  The reservoir is connected to the tubing that moves the insulin from the reservoir to the site.   

The site is the point where the insulin pump is connected to your body.  Insulin pump sites are inserted in the same places that are used for insulin administration by syringe –the abdomen, arms, buttocks, and thighs.  The pump site is inserted with a needle, but the needle is removed to leave a soft, pliable catheter in your body (called, the canula).   The pump site is usually changed every 2-3 days to prevent infections or the build- up of scar tissue that would interfere with insulin absorption.  


DEFINITION: A small wearable personal insulin delivery device 



  1. Reservoir = A cartridge in the pump that houses the insulin  
  1. Tubing = An “insulin hose” that carries insulin from the pump to the site 
  1. Site = The location where the pump attaches to the body. 

  Insulin pump sites are the same places as the insulin injection sites                           

  1. Infusion set= the cannula, needle, and adhesive bandage attached to the skin 
  1. Cannula = A small tube that remains in the body that delivers insulin to the site 
  1. Basal Rate = A continuous infusion of insulin that replaces the long acting insulin   
  1. Insulin to Carbohydrate Ratio (ICR) = The grams of carbohydrate that is covered by 

 1 unit of rapid acting insulin 

  1. Insulin Sensitivity Factor (ISF) or Correction Factor = The amount of blood sugar that is 

                                                                                                decreased by one unit of insulin   

  1. Target Blood Sugar = The blood sugar value that your pump is trying to maintain.   
  1. Active Insulin Time = The length of time insulin is working in your body. 
  1. Rapid acting insulin = The type of insulin used in an insulin pump e.g. Novolog, Humalog, Fiasp, Lyumjev etc.  

3.  What can I do to prepare for an insulin pump? 

  • To best prepare for insulin pump therapy, you should be competent in basic diabetes management and be an active participant in your diabetes care.  
  • You should have realistic expectations of insulin pump therapy and be motivated to learn new skills.  The insulin pump is not a magic cure for diabetes and does require the operator to check their blood sugar multiple times daily (or use a CGMS – Continuous Glucose Monitoring System ) as well as count carbohydrate grams at each meal 
  • Review ketone testing by blood or urine and have ketone testing supplies available before you start the insulin pump   
  • Learn how to count carbohydrates and practice your carb counting skills prior to starting on an insulin pump. 

4.  What are the key settings for the insulin pump? 

  • Basal  
  • Bolus 
  • Carbs 
  • Sensitivity 
  • Active insulin time 
  • Max Bolus 
  • Temporary Basal Rate 

Like the pancreas, the insulin pump only uses one rapid acting insulin that is delivered in two different ways.  

 A continuous infusion of rapid acting insulin, known as a basal rate, replaces the long acting insulin dose used in insulin injection therapy. Basal insulin’s job is to move sugar from the blood into your heart, lungs, muscles, etc.  to just keep you alive & functioning.  

 A dose of rapid acting insulin taken at meals or to correct a high blood sugar, is called an insulin bolus and replaces the rapid acting insulin doses given at mealtime with injection method.  

The bolus insulin is the extra “squirts” of insulin given by the insulin pump to correct a high blood sugar and/or cover the blood sugar rise from the carbohydrates eaten at meals.   

While basal rates are set in your pump by your healthcare provider, your pump calculates your bolus dose utilizing an Insulin to carb ratio (ICR); an Insulin Sensitivity Factor (ISF), also known as a correction factor, and a target blood sugar value.   

The insulin to carb ratio (ICR) is the grams of carbohydrate that are covered by 1 unit of rapid acting insulin.   

The Insulin Sensitivity Factor (ISF) or Correction Factor is the number of points that your blood sugar drops with 1 unit of insulin.  

 The target blood sugar is the blood sugar value that your pump is trying to obtain with the correction.   

 The pump’s bolus calculator uses these values, along with the blood sugar value and the carbohydrate amount that you enter in the pump to calculate your bolus dose. 

The insulin pump is able to administer insulin doses in fractions of a unit, allowing the pump to fine tune the basal and bolus amounts to the exact insulin needs of the wearer 

 All insulin pumps have Max Basal and Max Bolus settings.  These maximums serve to limit the amount of insulin given in either a basal or bolus dose to prevent low blood sugars.     

The Temporary Basal Rate allows the pump’s basal rate to be increased or decreased for a limited period of time.  Temporary basal rates allow the basal rate to be decreased to prevent a low blood sugar with exercise or increased to compensate for the rise in blood sugar during illness. Typically, you can set this Temp Basal Rate for 12-24 h at a time & most commonly as a % above or below the normal basal rate.  

 Bolus insulin doses can also be delivered in multiple speeds and timings to better correspond with the food digestion and blood sugar fluctuations of the wearer.                

The computer in the insulin pump also utilizes Active Insulin Time or Insulin On Board settings to track the amount of insulin that remains active in your body after a bolus insulin dose is given.  This prevents stacking of insulin doses too close together which could result in a low blood sugar.  

What are the advantages and disadvantages of an insulin pump? 

Insulin pumps provide flexibility in insulin dosing with the ability to adjust doses and settings in small fractions of a unit.   This pump function helps to tailor the insulin bolus dosages to the specific needs of the wearer. Thus, it can closely mimic the normal (physiological) insulin release from the pancreas. 

 Being able to correct a high blood sugar at the time that it occurs or being able to eat a variety of foods at variable times and amounts provides more flexibility and freedom with a lower insulin dosage. 

Pumps settings can be changed to fit the unique needs of the pump wearer.  Basal rates can be adjusted for different hours of the day, but long-acting insulin given by injection only allows for 1 fixed basal rate.   

The timing of the release of the bolus doses can also be adjusted to fit the timing of the release of blood sugar after a meal.    

Pump site changes every 2-3 days, instead of multiple daily injections, and is less stressful to people who are afraid of needles or just don’t like injections.    

Even though pumps are essentially safe, they are not perfect.  Insulin pumps are machines that can break. Tubing and sites can get pulled out or kinked.  Since insulin pumps only use rapid acting insulin, any interruption of insulin that lasts more than 1 hour puts the pump operator at risk of high blood sugar and possibly ketones that could result in developing DKA. Patient should therefore wear insulin pump all the time.  Site infections and scar tissue development may also occur.  Thankfully, these problems are rare events and safeguards have been developed to monitor and alert you to these problems.   

Frequent blood sugar monitoring and/or the use of a continuous glucose monitoring also helps the pump wearer to promptly identify and address any pump problems as they arise. 

Decrease the current total daily dose of insulin by 20-25%  Pumps are machines and can malfunction 
Able to make smaller dose changes in        fractions of a unit Pump has to remain attached consistently Can not be off pump for more than 1 hour 
Only uses one type of insulin  Rapid acting Less expensive to use vial of one type of insulin May develop ketones easier if pump off for more than one hour or site is kinked 
Able to correct blood sugar when necessary Must bolus for all meals, snacks and to correct blood sugar 

Find out if your insurance cover insulin pump therapy (most do). Medicare only ocvers insulin pump for those with type 1 diabetes or those with type 2 diabetes who are producing little insulin from their pancreas (you may need a blood test called the C-peptide test – a measure of insulin your pancreas are making). 

Take time chooseto choose your own insulin pump.  Sit down and look at and handle the different insulin pumps that you are interested in.  You may even want to ask for a demo.  Contact your health care provider for an insulin pump order and contact your insurance to verify your coverage.  You can get more information on insulin pump therapy from your diabetes healthcare provider, diabetes educator, and certified pump trainer. 



www.dexcom.com                        Dexcom CGMS 

www.medtronic.com                    Medtronic insulin pumps 

www.myomnipod.com                 Omnipod Insulin Pumps 

www.Tandemdiabetes.com         Tandem Insulin Pumps 

www.freestylelibre.us                   Freestyle libre CGMS 



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