Fasting for lab tests

It depends on the test. Fasting for a lab test typically lasts eight hours. Your doctor should give you any special instructions related to your tests, including fasting requirements. Always follow her or his instructions.

Glucose testing that checks blood-sugar levels and tests that determine your cholesterol, triglycerides, and high-density lipoprotein (HDL) levels usually require fasting. Other lab tests may require fasting, which is why you should ask your doctor. If you think fasting might be a problem, schedule your appointment for the early morning and bring a snack for after the appointment.

If it’s a test that does not require fasting then, yes, please eat something before having your blood drawn.

Unless your doctor says otherwise, take your usual medications. If you’re taking vitamin/mineral supplements, ask whether you should continue those as well.

Once you’ve had your blood drawn, you can eat and drink something immediately. It’s a good idea to bring a snack to your appointment. You can also schedule your blood test for the early morning, to minimize the length of time you’ll go without food.

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