Do I Need to Fast Before a Blood Test?

One of the most common questions at a diagnostic centre is: “Should I come empty stomach?” The answer depends on the test your doctor has advised.

Tests that usually need fasting

• Fasting blood sugar – usually 8–10 hours of fasting.
• Lipid profile (cholesterol, triglycerides) – often 9–12 hours, though your doctor may advise differently.
• Some liver and kidney panels, depending on your doctor’s instructions.

Tests that usually do not need fasting

• Complete blood count (CBC) and haemoglobin
• Thyroid profile (TSH, T3, T4)
• HbA1c
• Most urine tests

How to prepare

• Drink plain water during fasting — it keeps you hydrated and makes sample collection easier.
• Avoid tea, coffee, juice and chewing gum during the fasting period.
• Do not stop or change your regular medicines unless your doctor tells you to. Tell the technician which medicines you take.
• Try to get a normal night’s sleep and avoid heavy exercise before the test.

Not sure? Just ask

When you call or visit, tell our staff which tests you have been advised and we will let you know exactly how to prepare. Instructions can differ from person to person, so always follow your doctor’s advice first.

This article is for general awareness and is not a substitute for professional medical advice. Please consult a doctor for your individual situation.