HbA1c
HbA1c (glycated hemoglobin) reflects average blood glucose over the preceding two to three months and rises progressively with age in both sexes as glucose regulation declines across the population.
HbA1c is expressed as a percentage of hemoglobin that has been glycated. It is measured on the full (non-fasting) sample and reflects cumulative glycemic exposure rather than a single point-in-time measurement. These population percentiles include the full US population, including individuals with prediabetes and diabetes. HbA1c can also be reported in mmol/mol (IFCC units); to convert, use: mmol/mol = (% - 2.15) x 10.929.
Population Distribution
Box shows P25-P75. Line shows median (P50). Whiskers extend to P5 and P95. Hover for exact values.
Browse by Demographic
| Age (years) | male (%) | female (%) |
|---|---|---|
| 20-29 | 4.6–5.7 (5.2) | 4.7–5.7 (5.2) |
| 30-39 | 4.7–6.1 (5.3) | 4.8–6.3 (5.3) |
| 40-49 | 4.9–7.6 (5.5) | 4.9–6.5 (5.4) |
| 50-59 | 5–8.6 (5.6) | 5.1–7.8 (5.6) |
| 60-69 | 5.1–7.7 (5.7) | 5.1–7.7 (5.7) |
| 70+ | 5.2–8 (5.8) | 5.1–7.7 (5.8) |
Frequently Asked Questions
Why does HbA1c rise with age even without diabetes?
Several factors contribute: older red blood cells accumulate more glycation over time, kidney function declines subtly reducing erythropoietin stimulation (producing older average red cells), and underlying insulin resistance increases even in people without a diabetes diagnosis. The population distribution therefore shifts upward at every percentile with age.
How do I convert % to mmol/mol (IFCC units)?
Use the formula: mmol/mol = (% - 2.15) x 10.929. For example, 5.7% converts to approximately 39 mmol/mol. The mmol/mol unit is used by laboratories in the UK and most of Europe.
Why are these population percentiles and not clinical cut-offs?
Clinical cut-offs (such as 5.7% for prediabetes or 6.5% for diabetes) are diagnostic thresholds based on outcome data, not population distributions. These percentiles describe where a given value sits in the general US population, which is a different and complementary piece of information.
Related Analytes
- fasting-glucose - Metabolic panel (fasting glucose marker)