Fasting Blood Tests – Instructions

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Why Fasting is Important

Some blood tests require fasting to ensure accurate and reliable results. Please follow the instructions below carefully.

Timing Requirements for Fasting Tests

🔹 Fasting Blood Glucose Test

• Do not eat or drink (except water) for 8–12 hours before the test
• Water is allowed during the fasting period and on the morning of the test
• Blood must be drawn before 09:00 AM

🔹 Fasting Lipogram

• Requires a 12–16 hour fast
• Sample should be collected by 11:00 AM

Glucose Tolerance Test (GTT) – Preparation Guidelines

Before the Test:

1. Fast for 8–12 hours overnight
2. The test must begin no later than 09:00 AM
3. Only water is allowed during the fast and morning of the test – NO caffeine
4. Stop all non-essential medications for 3 days before the test
5. If you take essential medications (e.g., for blood pressure or cholesterol):
   • Skip them on the morning of the test
   • Bring them with you to take after the final blood sample
   • Provide a full list of medications to the lab

On the Day of the Test:

6. Do not smoke – this includes the morning and duration of the test
7. Remain seated and quiet throughout the test
   • The standard test lasts 2 hours, but it may take up to 5 hours depending on your doctor's request
8. For 3 days before the test, eat a diet with at least 150 g of carbohydrates per day

How to Reach 150 g of Carbohydrates per Day

Use the following list as a guide to ensure your diet includes enough carbs prior to testing:

• Bread (white/brown/whole wheat):
  • 1 slice (30–40 g) = 15–20 g carbs
• Cereals (Corn Flakes, Rice Krispies, Special K, etc.):
  • 1 serving (40 g) = 30–35 g carbs
• High-fibre cereals (All-Bran, Muesli):
  • 1 serving (40 g) = 20–25 g carbs
• Uncooked porridge (Maltabella, Oats, Pronutro, Taystee Maize):
  • 1 serving (30 g) = 20–30 g carbs
• Mealies (cooked on the cob):
  • 100 g = 20 g carbs
• Cooked pasta (plain):
  • 100 g = 30 g carbs
• Uncooked pasta (egg or instant noodles):
  • 100 g = 60–70 g carbs
• Potatoes (boiled with skin or baked):
  • 100 g = 20–25 g carbs
• Provita biscuits:
  • 100 g (packet) = 71 g carbs
• Uncooked rice:
  • 40 g (half a cup) = 20–25 g carbs
• Rusks (e.g. Ouma):
  • 1 rusk (35 g) = 24 g carbs
• Ryvita biscuits (original):
  • 1 slice (9 g) = 5.7 g carbs
• Canned sweetcorn or baked beans:
  • 100 g = 18 g carbs

📘 Reference: The New Complete Kilojoule, Carbohydrate and Fat Counter – South African Edition, 2006, Struik.

Need Help or Have Questions?

📍 Contact your nearest Ampath Care Centre or visit:
🌐 www.ampath.co.za