Fasting Sugar, PP Sugar, HbA1c — What Is the Difference?

Diabetes testing is not one test but three, and each answers a different question about how your body handles sugar.

Fasting blood sugar

This measures your sugar after 8-12 hours without food. It tells how well your body manages glucose overnight. A value above 126 mg/dL on repeat testing signals diabetes.

Post-prandial (PP) sugar

Taken exactly two hours after a meal, this shows how your body responds to food. Some people have normal fasting sugar but high PP sugar — which is why doctors ask for both together.

HbA1c — the 3-month report card

HbA1c reflects your average sugar over roughly three months. It does not need fasting and is the most reliable number for diagnosing diabetes and tracking long-term control. An HbA1c of 6.5% or higher indicates diabetes.

If you are above 35, overweight, or have a family history of diabetes, an HbA1c once a year is a wise habit.