Capillary Blood Glucose Test Procedures

Taking blood samples from the capillaries--the small blood vessels close to the skin--is a common way to obtain accurate measurements of concentration of glucose, or sugars, in the blood. Capillary blood tests can be done at home or in a laboratory, and usually consist of piercing the skin with a small needle called a lancet. Then the blood is collected and placed in a metering machine that determines the level of blood glucose.

At Home Testing

• At home monitoring is a daily ritual for people with type I or II diabetes. There are some metering machines that do not require the person to stick themselves with a lancet, but most people use a meter that requires a small droplet of blood on a test strip that is fed into the machine. To use this type of meter, you must first disinfect the area--usually a fingertip--with an alcohol swab and then allow the area to dry. Unwrap a new lancet needle, or use an automatic lancet device that pushes and retracts the lancet using a button, and position the lancet over your fingertip. Be sure that the angle of the needle runs perpendicular to the surface of your fingertip. If you lancet parallel to your fingertip, the blood can run down your finger in the grooves of your fingerprint. Prick yourself with the lancet, or press the automatic lancet button to activate. Allow the blood to bead on your fingertip, and then wipe away this first droplet. Catch the second droplet of blood onto the testing strip, and then press a gauze pad over the fingertip to stop the bleeding. Insert the test strip into your meter as directed by the manufacturer. Bandage your finger with an adhesive bandage, and then read the meter's results. Dispose of the lancet in an appropriate sharps container.

In Lab Testing

• Getting blood tested for capillary blood glucose in a laboratory is a similar procedure as testing your blood at home. A phlebotomist will take your hand, usually your non-dominant hand--and roll your fingertip gently to warm the area and increase blood flow. She will then disinfect the area using an alcohol swab. Using a lancet or an automatic lancet, the phlebotomist will then make a small puncture on your fingertip, and then allow the blood to bead. She will wipe away that first drop of blood, then collect the second and third drops of blood into a small, micro collection tube, seal the micro collection tube for lab testing, and place gauze square over your fingertip to stop the bleeding. While she waits for the bleeding to stop, she will dispose of the lancet in a sharps container. Finally, she'll place an adhesive bandage over your fingertip. Your health care provider will then give you the results of your blood glucose test.