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Fasting Instructions for Specific Lab Tests

To ensure that the results of your glucose tolerance test (GTT) , homocysteine test or lipid profile [link to procedure pages] are accurate, you will need to carefully follow your doctor’s directions regarding when to eat and when not to eat.

Typically, you will need to fast for 10 or 12 hours prior to having your blood drawn for the test. This means you should not eat food of any kind, and you should also avoid coffee, gum, candy and lozenges. You may drink water as desired, but this is the only exception.

Certain medications also may affect your test results. Consult your doctor before discontinuing use of any medications.

It is usually preferred that you start your fast in the evening and report to the lab for your test the following morning.  Your doctor will provide you with specific instructions to follow.

Michigan law requires that a valid order signed by an authorized person be presented before any laboratory test or procedure can be conducted. Authorized persons are defined as physicians, physician assistants, or nurse practitioners. These professionals are legally responsible for interpreting the results of tests based on their knowledge of the individual patient.