Glucose test
Key points
- A glucose test measures the amount of sugar (glucose) in the blood.
- Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand.
- The area is cleansed with antiseptic and punctured with a sharp needle or a lancet.
- The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experiences, and level of trust.
Alternative names
FBS; Blood sugar levels; Fasting blood sugar
Definition
A glucose test measures the amount of sugar (glucose) in the blood.
How the test is performed
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 airtight vial or a syringe. During the procedure, the tourniquet is removed to restore circulation. Once the blood has been collected, 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 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
Adults should fast (not eat) for 6 hours before the test.
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 experiences, 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:
- Infant test/procedure preparation (birth to 1 year)
- Toddler test/procedure preparation (1 to 3 years)
- Preschooler test/procedure preparation (3 to 6 years)
- Schoolage test/procedure preparation (6 to 12 years)
- Adolescent test/procedure preparation (12 to 18 years)
A random serum glucose test can be performed at any time but will reflect such factors as dietary intake and activity.
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
Written and revised by
David Cohen, M.D.
Our doctors write and review articles for accuracy and keep them up to date.
health.am provides general information, not medical advice. Always consult a qualified health professional about your own health.