Insulin test |
| Definition: |
| A blood test that measures the amount of insulin, a hormone that regulates blood sugar. |
| How the test is performed: |
| Adult or child: Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet (an elastic band) or blood pressure cuff is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the tourniquet to distend (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 tourniquet is removed to restore circulation. Then, the needle is removed and the puncture site is covered to stop any bleeding. 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 for the test depends on the reason for the insulin measurement. 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. Infants and children: The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:
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| 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: |
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The most important reason for measuring the serum insulin level is in the diagnosis or evaluation of hypoglycemia (low blood sugar). Insulin is a hormone released from the beta cells of the pancreas. Insulin's most important function is to facilitate glucose 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. |
| Normal Values: |
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5-20 mcU/mL while fasting Note: mcU/mL = micro unit per milliliter |
| What abnormal results mean: |
Greater-than-normal levels may indicate:
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| What the risks are: |
| Special considerations: |
| Obesity decreases the sensitivity of various tissues to insulin, which normally results in a compensatory increased insulin production by the pancreas. Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others. |
Reviewed By: Stephanie Fish, M.D., Division of Endocrinology, University of Pennsylvania Medical Center, Philadelphia, PA. Review provided by VeriMed Healthcare Network.
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