Blood glucose test
blood sugar test · fasting glucose · sugar test · glucose test
This test shows how much sugar is in your blood right now. Blood is taken from a vein or a finger.
To check for diabetes, if you are very thirsty, pee often, or feel weak, at a checkup, and to monitor treatment.
⏱ Duration: the blood draw takes 2 to 5 minutes. Results usually come the same day or the next
Be sure to tell your doctor
How to prepare
- Food. Strictly fasting: usually 8 to 14 hours without food. Plain water is fine.
- The day before. Have a normal dinner, without overeating or alcohol. Do not change your diet in the days before the test.
- In the morning. Do not smoke, chew gum, or drink sweet drinks, tea, or coffee.
- Medicines. Do not stop them on your own. If you have diabetes, ask your doctor how to take your medicines on the test day.
What to bring
- Your referral
- Your ID
- Some food, to eat right after the test, especially if you have diabetes
How it goes
- You sit down and rest your arm on the table
- The skin is cleaned with antiseptic
- A quick prick in a vein or a finger
- Blood fills the tube
- A cotton pad is pressed on the spot
What you'll feel
- A quick prick
Afterwards
- You can eat right after the test
- Your doctor reviews the result. If in doubt, the test is repeated or other tests are ordered
Contact a doctor straight away if
- If you have diabetes: if you feel shaky, have a cold sweat, or feel confused while fasting, eat some sugar and tell the nurse
Common questions
Can I brush my teeth before a blood sugar test?
Usually it is better without toothpaste, or with sugar-free toothpaste. It is a small thing, but some labs ask for it.
Is finger blood the same as vein blood?
Almost, but the numbers differ a little. To make a diagnosis, doctors more often use blood from a vein.