HbA1c and fasting glucose are different measurements. Do not treat one as a direct replacement for the other, or use a single result to diagnose yourself.
A snapshot and a longer view
HbA1c reflects average blood glucose over approximately three months and is reported as a percentage. Fasting glucose measures glucose at the time of a blood draw after a specified fast. Both can be clinically useful, but they answer different questions.
For example, a fictional report might show HbA1c of 5.8% and fasting glucose of 104 mg/dL. These are two different scales, not two versions of the same number. Read each with its own context.
What the common HbA1c thresholds mean
The CDC describes HbA1c below 5.7% as normal, 5.7–6.4% as the prediabetes range and 6.5% or above as the diabetes range. These categories support clinical assessment; they are not a substitute for a diagnosis. Confirmation may be needed, particularly without clear symptoms.
If a result crosses a threshold, ask the clinician what it means for you and whether it needs confirmation. Do not adjust prescribed medication on the basis of a website example.
When the readings do not seem to agree
An unexpected difference is worth discussing rather than averaging away. Some haemoglobin variants can interfere with some HbA1c methods. Ask whether the measurement fits the rest of the clinical picture.
Keep both original results and their dates. Tell the clinician whether fasting instructions were followed and provide your medicines and relevant history. This makes the question specific: “Do these readings need clarification?”
Choose a test for a reason
A bigger package is not automatically a better answer to a focused question. Before booking, identify whether the aim is a baseline, follow-up of an earlier finding or clinician-directed monitoring.
Bio U’s package pages list their inclusions and preparation instructions. If you already have a prescription or previous report, the team can help you locate the listed tests. Clinical decisions about which test is appropriate remain with your clinician.
Common questions
Does HbA1c itself require fasting?
HbA1c generally does not. Other tests collected in the same appointment may require it; follow the preparation instructions for the entire booking.
What should I do if the readings disagree?
Take both source reports to your clinician. Ask whether the difference could relate to timing, preparation or factors affecting the test, and whether confirmation is needed.
Sources & further reading
Sources accessed 27 September 2026. This guide is general education, not an individual diagnosis or treatment plan. Send a correction or question.