Insulin test

Definition

This is a blood test that measures the amount of insulin, a hormone that regulates blood sugar.

How the test is performed

Blood is drawn from a vein on the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and an elastic band is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the band to fill with blood.

A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. After the blood is drawn, the band is removed to restore circulation. Then, the needle is removed, and the puncture site is covered to stop any bleeding.

For an infant or young child:

The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.

How to prepare for the test

The preparation depends on the reason for testing your insulin levels. Ask your health care provider if you should fast prior to the test. The health care provider may advise you to withhold medications that can interfere with the test, including injected insulin and/or oral antidiabetic medications.

For infants and children:

The preparation you can provide for this test depends on your child's age and experience. For specific information regarding how you can prepare your child, see the following topics:

• infant test or procedure preparation (birth to 1 year)
  
• toddler test or procedure preparation (1 to 3 years)
  
• preschooler test or procedure preparation (3 to 6 years)
  
• schoolage test or procedure preparation (6 to 12 years)
  
• adolescent test or procedure preparation (12 to 18 years)
  

How the test will feel
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the test is performed

Insulin is a hormone released from the beta cells of the pancreas. Insulin's most important function is to facilitate glucose (blood sugar) uptake by a variety of tissues, especially adipose (fat) and skeletal muscle. Insulin also stimulates the synthesis and storage of triglycerides and proteins. Insulin is the most important regulator of blood glucose. High blood glucose (such as exists shortly after a meal) stimulates the release of insulin, whereas low blood glucose levels inhibit insulin release.