How To Prepare

Fasting blood sugar (FBS)

For a fasting blood sugar test, do not eat or drink anything other than water for at least 8 hours before the blood sample is taken.

If you have diabetes, you may be asked to wait until you have had your blood tested before taking your morning dose of insulin or diabetes medicine.

2-hour postprandial blood sugar

For a 2-hour postprandial test, start eating a meal exactly 2 hours before the blood sample is taken. A home blood sugar test is the most common way to check 2-hour postprandial blood sugar levels.

Random blood sugar (RBS)

No special preparation is required before having a random blood sugar test.

Oral glucose tolerance test and glycohemoglobin A1c

For information on preparing for an oral glucose tolerance test or glycohemoglobin A1c test, see the topic Oral Glucose Tolerance Test or Glycohemoglobin A1c for more information.

Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results may mean. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).