Insulin Basics

What is insulin?

Insulin is a hormone produced by the beta cells in our pancreas. Insulin’s job is to keep our blood glucose in a safe range.  It does this by allowing glucose to leave the bloodstream and be used by the body for energy. 

How insulin works

When we eat, a simple sugar called glucose enters the bloodstream. Glucose mainly comes from carbohydrates. When the pancreas detects a rise in blood glucose, it secrete insulin. Insulin then unlocks the door on all of your body’s cells, allowing glucose molecules to enter.  

Insulin and type 1 diabetes

For someone with type 1 diabetes, beta cells no longer produce insulin. Without insulin, the body’s cells begin to starve as glucose builds up in the bloodstream and causes damage to the blood vessels. Someone with T1D must take insulin as it is a “life sustaining” hormone.  This can be done by injection, an insulin pump or with inhaled insulin. 

Insulin and type 2 diabetes

A person with type 2 diabetes still produces insulin, however their body’s cells do not use insulin properly. People with type 2 diabetes often use medication and sometimes take insulin to help transport glucose into the body’s cells and use it for energy.  

Proper Insulin Storage and Use

Insulin must be stored properly in order to maintain its potency. It is sensitive to light and temperature. Being kept too hot or too cold will impact its ability to work correctly, causing the user to have difficulty controlling their glucose levels.

Tips to safely store insulin

• Unopened bottles should be kept in the refrigerator at a temperature between 36°F- 46°F (2°C- 4°C)
• Opened insulin vials, pens or reservoirs can be kept at room-temperature between 59°F - 86°F (15°C - 30°C)
• Do not allow insulin to freeze, either in certain parts of the refrigerator or by being put in the freezer. 
• Insulin can be stored at room-temperature for approximately one month. Be sure to check the exact usage time below:

  Type of Insulin	Discard after
  Novolog, Humalog, Apidra	28 days
  Lantus, Basaglar	28 days
  Levemir	42 days
  Tresiba	56 days

• Keep insulin away from direct sunlight and heat. Avoid putting it on places such as windowsills or dashboards. Do not use insulin that has been left in a car or exposed to temperatures above 96°F (37°C)
• Always check the expiration date on the insulin box/vial/pen. Insulin can be stored and used until expiration as long as it has been stored properly. 
• Do not use insulin if it has formed crystals, changes color, or comes from a vial with a rubber stopper that is dry and cracked. 

Different Types of Insulin

There are a variety of insulins available and all work at different speeds!

Insulins are grouped based on how quickly they work in the body and how long their action lasts. In general, inhaled, ultra-rapid and rapid insulins are fast-acting and are used for meals, snacks and when blood sugars are high. Intermediate and long-acting insulins start slower and have a flatter peak. They are, in some cases, used for delayed meal coverage, when fasting, between meals or overnight.  Long-acting insulin is often referred to as basal insulin. Its action is slow and steady, has no peak and is used to keep blood glucose levels stable between meals and overnight. 

To see the insulin action times for various insulin types, take a look at the Insulin Action Curve chart.  

References

How does insulin work? 

©Gary Scheiner MS, CDCES – Integrated Diabetes Services. May be reproduced and used for patient education, but not sold.