Hemoglobin A1C (HbA1c)
HbA1c shows how well your blood sugar has been controlled over the past three months. High levels increase the risk of long-term complications, even if your daily readings seem fine. That’s why this test is so important for everyone living with diabetes.
This content is not medical advice. Always consult your healthcare or diabetes care team before making any changes to your diabetes treatment or daily management.
What Is HbA1c?
Hemoglobin A1c (HbA1c) is a lab test that reflects your average blood glucose over the past 3 months. Glucose attaches to hemoglobin — a protein in red blood cells and remains bound for the cell’s lifespan, which is typically about 120 days. The higher the blood sugar, the more hemoglobin becomes “glycated” resulting in a higher HbA1c percentage.
Although daily glucose checks are useful for moment to moment insights, HbA1c provides a broader view of how well blood sugar has been managed over time. It is especially important for individuals with type 1 diabetes, as it helps evaluate overall treatment effectiveness.
Why Is HbA1c Important?
A high HbA1c level not only reflects poor glucose control, but also an increased risk of chronic complications such as damage to the eyes (retinopathy), kidneys (nephropathy), nerves (neuropathy), and cardiovascular system. Research (such as the well-known DCCT study) has shown that lowering HbA1c by just 1% can significantly reduce the risk of these complications.
Clinical research, such as the DCCT study, shows that lowering HbA1c by 1% can significantly reduce these risks:
76% for eye complications
50% for kidney complications
60% for nerve damage
35% for cardiovascular complications
This highlights why even small improvements in HbA1c levels can have meaningful health benefits.
Remember that the HbA1c value is not a replacement for regular self-monitoring.
It provides only additional information about long-term trends in blood sugar levels.
HbA1c Levels and Diabetes Risk
| Category | HbA1c Levels | Description |
|---|---|---|
| Normal Range | 4% – 5.6% | Considered normal for people without diabetes. |
| Prediabetes | 5.7% – 6.4% | Higher than normal blood sugar levels, increase the risk of developing type 2 diabetes without lifestyle changes. |
| Diabetes | 6.5% or higher | Indicates consistently elevated blood sugar levels, requiring medical management to prevent diabetes complications. |
What is the Normal Range for HbA1c by Age?
| Age Group | Normal HbA1c Range |
|---|---|
| Adults (20 years and older) | Below 5.7% |
| Children (Under 6 years) | Below 8.5% |
| Children (6 to 12 years) | Below 8% |
| Teens (13 to 19 years) | Below 7.5% |
Why Monitoring HbA1c and Time in Range (TIR) Matters?
While HbA1c provides a long-term overview of blood sugar control, it doesn’t show daily fluctuations. That’s where Time in Range (TIR) becomes important.
HbA1c shows your average glucose over the past 3 months.
TIR measures the percentage of time your blood glucose stays within a target range, typically 70–180 mg/dL (3.9–10 mmol/L).
Why This Matters:
A person can have a “good” HbA1c but still experience dangerous highs and lows.
TIR helps identify how stable your blood sugar is throughout the day.
Higher TIR is linked to a lower risk of complications, especially heart, eye, nerve, and kidney damage.
Recommended Targets:
TIR goal: At least 70% of the day in the target range (about 17 out of 24 hours).
HbA1c goal: Usually below 7%, unless your doctor recommends otherwise.
Monitoring both HbA1c and TIR gives a fuller picture of your diabetes control and helps guide personalized treatment.
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