HbA1c and fasting glucose describe different parts of the blood sugar picture. HbA1c reflects roughly the previous two to three months. A glucose measurement describes the level when the sample is taken. One can therefore be abnormal while the other is within its reference interval.
Is one test better?
That depends on the question being investigated. Your clinician considers symptoms, other conditions and whether you already have diabetes. A single number should not be used to diagnose yourself or rule a condition out.
Swedish laboratories usually report HbA1c in mmol/mol and glucose in mmol/L. These are different measurements: an HbA1c of 40 does not mean a blood glucose of 40. Keep the test name and unit with every result.
What differs between the tests?
| Test | Time frame and preparation |
|---|---|
| HbA1c | A longer-term average; fasting is not required for this test alone. |
| Fasting glucose | The level at sampling after the instructed fasting period. |
| Glucose tolerance test | Blood samples before and after a standard glucose drink, with specific preparation. |
What should your clinician know?
Mention if you did not follow fasting instructions, were ill when tested or have a blood disorder. Changes affecting haemoglobin or red blood cells can make HbA1c difficult to interpret. It cannot always replace other investigations.
Do not make drastic short-term dietary changes simply to improve a number. Follow the preparation for the test that was actually ordered and ask for follow-up that can be compared meaningfully with earlier results.
Four questions for your appointment
- Why was this particular test ordered?
- Does an abnormal result need confirmation?
- Is my personal treatment target different from the laboratory reference interval?
- When should it be followed up and who will contact me?
Do not wait for routine testing if symptoms develop
Contact a vårdcentral, a primary care centre, about increased thirst, passing large amounts of urine or unexplained weight loss. Rapid deterioration with vomiting, abdominal pain or altered consciousness needs emergency assessment. Call 112 for unconsciousness. Call 1177 if you need advice on where to seek care in Sweden.
Sources and further reading
- 1177: Blodprov HbA1c (in Swedish)
- 1177: Blodprov P-Glukos (in Swedish)
- 1177: Glukosbelastning (in Swedish)
- 1177: Diabetes typ 1 (in Swedish)
Sources and links checked on 22 October 2026. Editorial team: Hagakliniken. General information; individual assessment may differ.