2) BLOOD GLUCOSE 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, your doctor may ask you to wait until you have had your blood collected before taking your morning dose of insulin or diabetes medicine. 2-hour Postprandial (post lunch) blood sugar: For a 2-hour postprandial test, you need to have your blood collected exactly 2 hours after a regular lunch. e.g. If Mr. Shah has completed his lunch at 12.00 noon he needs to complete his blood collection at 2.00 pm. Mr. Shah will require to reach the lab at 1.50 pm, i.e. 10 minutes early to avoid registration delays. Also Mr. Shah cannot have any food between 12.00 noon and 2.00 p.m. time period. He can have water and his usual medicines. Random blood sugar (RBS): No special preparation is required before having a random blood sugar test.