On your medical report, "HbA1c 6.8%" — the doctor glanced and said "it's high," but you might still be puzzled: What exactly is this? How is it different from fasting blood glucose? How low is considered good?
Glycated hemoglobin (HbA1c) is the product of hemoglobin in red blood cells combining with glucose. Red blood cells have a lifespan of about 120 days, so HbA1c reflects the average blood glucose level over the past 2–3 months, unaffected by a single extra meal or a sleepless night. It is the "gold standard" for diagnosing diabetes and the "midterm exam score" for evaluating blood sugar control.
Normal values, diagnostic values, and control targets: three tables explained at once
| Range | HbA1c Value | Meaning |
|---|---|---|
| Normal | <5.7% | Healthy glucose metabolism |
| Prediabetes | 5.7%–6.4% | Golden window for intervention, reversible |
| Diabetes diagnosis | ≥6.5% | Needs combination with symptoms or repeat testing |
| General control target | <7.0% | Goal for most people with diabetes |
| Strict target | <6.5% | For those with short disease duration, no complications |
| Relaxed target | <8.0% | For elderly, those with severe complications |
Note: HbA1c ≥6.5% is the diagnostic threshold, not a "passing line." Keeping it below 7% can reduce the risk of microvascular complications by about 40%.
Why is fasting blood glucose normal, but HbA1c high?
This is very common in prediabetes. Fasting blood glucose only reflects "that one point in the morning," while HbA1c reflects the "average level over 24 hours a day." Many people barely pass the fasting test, but their postprandial blood glucose remains persistently elevated at 10–12 mmol/L, and HbA1c faithfully records it.
💡 Chinese data: Over 50% of diabetes patients have only elevated postprandial blood glucose
Measuring only fasting glucose is like only seeing the tip of the iceberg.
How often should you test?
- At initial diagnosis or after adjusting treatment: every 3 months
- After stable blood glucose targets are met: every 6 months
- During prediabetes reversal: monitor every 3 months
A practical goal breakdown
Reducing HbA1c from 8% to 7% means lowering average blood glucose from about 10 mmol/L to about 8.6 mmol/L. How to achieve it? Not by skipping a meal, but by reducing postprandial blood glucose fluctuations by 2 mmol/L each day, sustained for 3 months. Behind this is a three-dimensional synergy of increased muscle mass, stable hepatic glucose output, and improved insulin sensitivity—building muscle, nourishing the liver, and regulating the pancreas—none of which can be omitted.
⚠️ Important reminder
This article is for health education purposes and does not constitute medical advice. HbA1c may be inaccurate in those with anemia or hemoglobin disorders; combine with fasting blood glucose and glycated albumin for comprehensive assessment.
