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Insulin Free and Total Blood Test

An Insulin Free and Total Blood Test includes Insulin Free and Insulin Total.

Sample Report

Test Code: 501561

CPT Code: 83525, 83527

Also Known As:

Methodology: Chemiluminescent immunometric assay (IMA) after insulin extraction of free and total insulin

Specimen Type: Blood

Preparation: Fasting for 12 hours required. Stop biotin consumption at least 72 hours prior to the collection.

Test Results: 8-10 days. May take longer based on weather, holiday or lab delays.



The test requires individuals to fast for 12 – 14 hours before giving blood for the test.  Individuals are allowed to drink water and to take medications during the fast.
Why It Is Used
The insulin free test or insulin total test is primarily used as a test of Type 2 diabetes, insulin resistance, and of hypoglycemia.   

How It Works
This blood test assesses the level of free insulin and the total insulin in the blood. Some insulin is bound to other substances like proteins.  Individuals who are undergoing insulin treatment for diabetes will often have higher levels of bound insulin in their blood than normal.  Free insulin, on the other hand, is not attached to any proteins and floats freely though the blood.  Total insulin is the level of both bound and free insulin. 

Insulin is released into the bloodstream from the pancreas in response to increased levels of blood glucose.  Insulin helps to transport the glucose from the blood into the cells where it is stored so that it can be used for energy.  In an individual with diabetes, however, insulin is either not properly produced or the insulin is blocked from moving the glucose into the cells.  This process can cause insulin levels to spike as the body tries to counteract the resistance.  Whereas low levels of insulin can lead to problems such as heart disease, kidney and liver problems, and vision problems, high levels of insulin can lead to hypoglycemia and low blood sugar.  The appropriate balance of insulin in the body is important in maintaining overall health.

Test results are interpreted by looking at the levels of free insulin as well as total insulin found in the blood.  Insulin is measured in international units µIU/m.  Normal results vary based on what test is being used.  The following results are representative numbers based on the insulin free and total blood test. 

  • Total insulin levels < 5 µIU/m fall within the abnormally high range of blood insulin
  • Total insulin levels > 15 µIU/m fall within the abnormally high range of blood insulin

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