No food, no smoking, no chewing gum and no carbonated drinks from 10pm the day before the exam. You may drink small amounts of juice, water or clear tea/coffee up to 4 hours before the exam, but nothing after that time. If you are diabetic, do not take your insulin/diabetic pills until after the exam is complete. Expect to be at the clinic for a total of 30 minutes to 1 hour for this exam.