Tests, Labs & Imaging

Diagnostic Laboratories

Patient Information: Fasting Blood Tests

If your doctor orders a fasting blood test, you should not have anything to eat or drink for 12 hours before you go to the laboratory to have your blood taken. Some examples of fasting blood tests are fasting glucose, fasting triglycerides, fasting lipids and glucose tolerance.

Please note that for a glucose tolerance test, you will need to stay in the laboratory for one or two hours (depending on the specific test your doctor ordered), so you may want to bring a book, game or handwork to do while you wait.

Here are answers to some commonly asked questions about fasting.

Can I drink water?
Yes, you may drink small amounts of water.

Should I take my medication?
Yes, you should take any medication which has been prescribed to you by your doctor unless your doctor tells you not to.

Can I drink juice?
No.

Can I drink coffee or tea?
No.

Can I chew gum?
No.

Can I smoke?
No. Smoking can affect your test results.

Can I go to my exercise class?
No. Exercise can affect your test results.