Preparation for glucose blood tests focuses on general preparation, food and medication.

• General preparation
  
• • Patients should be in good health before glucose tests and free of all illnesses, including colds. 
    
    
• Foods
  
• • Fasting plasma glucose test. Requires patients to fast overnight prior to testing. On the day of testing, patients should not smoke or consume coffee or other caffeinated products.
    
    
  • Oral glucose tolerance test (OGTT). Requires patients to eat a diet rich in carbohydrates for three days prior to the test. Such foods include bread, grains, starchy vegetables and fruit. On the evening before the test the patient fasts. On the testing day patients should not smoke or consume caffeine. Carbohydrate loading is not necessary for pregnant women taking an OGTT as a means of screening for gestational diabetes.
    
    
  • Two-hour postprandial blood sugar test. Requires patients to eat a high-carbohydrate meal exactly two hours before the test.
    
    
• Medications and supplements. A variety of medications and dietary supplements may raise or lower glucose (blood sugar) levels. Patients should inform their physician about medications taken, including those for the following conditions:
  
• • Depression
  • High blood pressure
  • Abnormal cholesterol levels
  • Hormonal therapy
  • Seizures
  • Tuberculosis
  • Pain relief, including aspirin