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Fasting Blood Sugar

What is it?

A fasting blood sugar (FBS) is a test that measures the amount of sugar in your blood. Fasting means you have not had food or drink for at least 8 hours. This test may be called a fasting blood glucose. Glucose is the simplest form of sugar and is the main source of energy for your body.

Why do I need it?

If you have symptoms that suggest diabetes (di-uh-b-tees) mellitus (mel-i-tus), a fasting blood sugar may be done. The results of this test can tell if you have diabetes mellitus or need further testing. For more information, ask your caregiver for the CareNotes™ handout about Diabetes Mellitus. If you have diabetes mellitus, sometimes FBS is done to see if your sugar control is what it should be. The following symptoms are reasons your caregiver may want you to have this test:

  • Blurred vision.
  • Excessive hunger.
  • Excessive thirst.
  • Excessive urination.
  • Unexplained weight loss.
  • Difficulty with wound healing

How do I get ready for the test?

Your caregivers will tell you when to have your blood test done. Do not eat or drink anything, except water, for at least 8 hours before the test. Ask your caregivers if you should wait to take your medicines until after your blood is taken.

How is the specimen collected?

A caregiver will put a wide rubber strap around your arm and tighten it. Your skin will be cleaned with alcohol. A small needle attached to a special test tube will be put into a vein in your arm or hand. The tube has suction to pull the blood into it. When the tube is full, the rubber strap, needle and tube are removed. The caregiver will press a piece of cotton where the needle was removed. You may be asked to hold the cotton on the site for a few minutes to help stop the bleeding. Tape may then be put over the cotton on your arm.

What do I do after the test?

You may remove the tape and cotton in about 20 to 30 minutes. Call your caregiver to get the results of your test. Your caregiver will explain what your test results mean for you. Follow the instructions of your caregiver.

Care Agreement

You have the right to help plan your care. To help with this plan, you must learn about your lab tests. You can then discuss the results with your caregivers. Work with them to decide what care may be used to treat you. You always have the right to refuse treatment.