HbA1c
Hemoglobin A1c (HbA1c) measures the percentage of hemoglobin molecules that have glucose permanently attached (glycated). Since red blood cells live approximately 120 days, HbA1c reflects the weighted average blood glucose over the past 2-3 months, with the most recent 30 days contributing disproportionately.
Why it matters: HbA1c reflects long-term average glucose and is widely used to assess glucose control over the prior 2-3 months. Each 1% change in HbA1c corresponds to roughly 2 mmol/L difference in average glucose. Lower HbA1c over time is generally associated with fewer diabetes-related complications.
May increase with:
May decrease with:
What is HbA1c?
Hemoglobin A1c (HbA1c) measures the percentage of hemoglobin molecules that have glucose permanently attached (glycated). Since red blood cells live approximately 120 days, HbA1c reflects the weighted average blood glucose over the past 2-3 months, with the most recent 30 days contributing disproportionately.
What might a high or low HbA1c mean?
HbA1c reflects long-term average glucose and is widely used to assess glucose control over the prior 2-3 months. Each 1% change in HbA1c corresponds to roughly 2 mmol/L difference in average glucose. Lower HbA1c over time is generally associated with fewer diabetes-related complications.
What is the typical reference range for HbA1c?
The general-population reference range shown here is < 6 %. Reference ranges describe the general population and are not a personal target — discuss your results with your physician.
What can affect HbA1c?
It may be higher with: Chronically elevated blood sugar, Insulin resistance, High carbohydrate diet, Physical inactivity, Iron deficiency (falsely elevates), Splenectomy, Chronic kidney disease. It may be lower with: Low-carb diet, Regular exercise, Weight loss, Diabetes medications (metformin, GLP-1 agonists), Improved sleep, Stress management, Recent blood loss or transfusion (falsely lowers), Hemolytic anemias (falsely lowers).