Blood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with a germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.
Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.
In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.
In the laboratory, a technician performs a test on the sample that tags proteins so that they can be viewed and studied.
No special preparation is necessary.
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.
This test may be performed if you have, or are at risk for, type 1 diabetes. It also may be done if you appear to have an allergic response to insulin, or if insulin no longer seems to control your diabetes.
Normally, there are no antibodies against insulin in your blood.
Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
If you have IgG and IgM antibodies against insulin, your body reacts as if the insulin is foreign. This may make insulin less effective, or not effective at all.
The antibodies can also change the amount of time it takes insulin to work, putting you at risk for low blood sugar. This means that the insulin cannot move glucose from the bloodstream into the cells. As a result, increased levels of insulin are needed to have the same effect, which is called insulin resistance.
If the test shows high levels of IgE antibody against insulin, your body has developed an allergic response to the medication. This could put you at risk for skin reactions, or more severe reactions. Other medications, such as antihistamines or low-dose injectable steroids, may help to lessen the reaction. If reactions have been severe, an in-hospital procedure called desensitization may be necessary.
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.
Other risks associated with having blood drawn are slight but may include:
- Excessive bleeding
- Fainting or feeling lightheaded
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
Buse JB, Polonsky KS, Burant CF. Diabetes mellitus. In: Kronenberg HM, Melmed S, Polonsky KS, Larsen PR. Williams Textbook of Endocrinology. 11th ed. Philadelphia, Pa: Saunders Elsevier; 2008:chap 30.
Eisenbarth S, Polonsky KS, Buse JB. Type 1 diabetes mellitus. In: Kronenberg HM, Melmed S, Polonsky KS, Larsen PR. Williams Textbook of Endocrinology. 11th ed. Philadelphia, Pa: Saunders Elsevier; 2008:chap 31.