HbA1c vs Fasting Glucose: Which Test Do You Need?

HbA1c and fasting glucose both provide information about blood sugar, but they measure different things. Neither test is automatically “better” — a healthcare professional chooses the right test based on your situation.

What is a fasting glucose test?

A fasting glucose test measures glucose in your blood after you have not eaten for a set period, often overnight. It shows what your blood sugar is doing at one specific point in time.

It can be affected by a recent illness, stress, medication and whether you were truly fasting.

What is an HbA1c test?

An HbA1c test estimates your average blood glucose over roughly the past two to three months. It does not require fasting and can be especially helpful for monitoring longer-term control.

However, HbA1c may be less reliable in some situations, including certain blood disorders, pregnancy or conditions that affect red blood cells.

Why might a clinician use both?

The tests answer different questions. A fasting result is a snapshot. HbA1c gives a longer-term average.

If symptoms, risks and test results do not match, your clinician may order a repeat test or use another method before making a diagnosis. Do not assume a single result confirms or rules out diabetes.

Keep the full picture together

Tracking home glucose readings and recording HbA1c results gives useful context for appointments. Pulse keeps both in one place, alongside blood pressure. Start with Pulse.