Explaining active insulin

What is active insulin?

When insulin is delivered into your body, it doesn’t immediately disappear; it continues to work for a certain period of time, lowering your blood sugar levels. Active insulin refers to the amount of insulin that is still working in your body after you have given a dose of insulin.

Diabetes technology such as insulin pumps and smart insulin pens keep track of active insulin to ensure you aren’t giving another dose too close to your previous dose, which is also known as insulin stacking. This is an important safety feature to help avoid delivering too much insulin which could lead to low blood sugars.

 

Active insulin time

Active insulin time is how long the insulin is working to lower your glucose levels. The duration typically varies depending on the type of insulin used. For example, the rapid-acting insulin used in an insulin pump works for about 3-4 hours in most adults. Your healthcare team will personalize the active insulin time you program into your pump system based on a variety of factors, including age and historic glucose data.

 

Bolus WizardTM feature

The Bolus WizardTM active insulin time setting lets the pump know how long insulin continues to work in your body. It calculates the amount of active insulin and subtracts that amount before estimating a bolus. In other words, if the Bolus WizardTM calculator recommends that you give a reduced amount of correction insulin or no correction insulin, it's because you have active insulin remaining from a previous bolus. This may help prevent hypoglycemia from overcorrecting for a high glucose level.

 

Active insulin time with SmartGuardTM technology

Did you know that active insulin time is different when using the SmartGuardTM feature (automated insulin delivery mode) on the MiniMedTM 780G system? When in SmartGuardTM, active insulin time is used as a lever to strengthen automatic correction doses and doesn’t relate to how long the insulin lasts in the body. The recommended setting in SmartGuardTM technology is two hours. This allows the system to step in sooner to help correct high blood sugars. Don’t worry, the system is working behind the scenes to prevent stacking of insulin and will subtract insulin from your bolus doses if needed.

 

[Originally published 2013-10-14. Updated 2025-01-15]