HbA1c measures sugar attached to red blood cells, which live about three months. It reflects average glucose over that period, not one morning.
The ranges
Under 5.7% is generally normal; 5.7% to 6.4% indicates prediabetes. Diabetes is 6.5% or higher, confirmed by repeat test. Your doctor may set your target.
Why it can mislead
Red blood cell lifespan affects HbA1c. Iron deficiency anaemia can raise it; blood loss, haemoglobin variants, pregnancy and kidney disease can also affect results. Ask your doctor about conflicting glucose readings.
How fast it moves
HbA1c changes slowly; retest after about three months. Case studies showed meaningful drops in three to six months.
A useful pairing
Fasting glucose captures mornings, HbA1c the prior quarter, and post-meal readings or CGM show meal responses.
Education, not personal medical advice. Consult a qualified clinician about diagnosis, treatment and your results.