Diabetes
Glycated Haemoglobin (HbA1c)
HbA1c measures the proportion of haemoglobin that has become glycated by glucose, reflecting average blood glucose exposure over roughly the preceding 8 to 12 weeks. At the point of care it lets clinics screen for, diagnose and monitor diabetes from a fingerstick sample within minutes, without sending the patient to a laboratory.
Why it is measured
Because it integrates glucose exposure over the lifespan of the red cell, HbA1c is far less affected by short-term fluctuations, fasting state or recent meals than a single glucose reading. This makes it a stable, internationally standardised marker for long-term glycaemic control and a recognised diagnostic test for type 2 diabetes.
| Typical range | Indicative adult (non-pregnant) values, reported in IFCC and NGSP units: normal below 42 mmol/mol (below 6.0%); non-diabetic hyperglycaemia / increased risk 42 to 47 mmol/mol (6.0 to 6.4%); diabetes 48 mmol/mol (6.5%) or above, confirmed on a separate sample in asymptomatic people. Management targets are individualised and often set around 48 to 58 mmol/mol (6.5 to 7.5%). Ranges and cut-offs vary by method, assay calibration and clinical guideline, and HbA1c can be unreliable in conditions affecting red-cell turnover (for example haemoglobinopathies, recent transfusion, anaemia, pregnancy or chronic kidney disease), so interpret against the issuing service's reference values. |
|---|---|
| Sample | Capillary fingerstick or venous whole blood, typically 1 to 4 microlitres collected directly into the device cartridge or a supplied capillary holder; no fasting required. |
| Turnaround | Approximately 3 to 6 minutes per sample at the bedside or in clinic, depending on the analyser. |
Point of care devices that report it
- Abbott Afinion 2 (and Afinion AS100)
- Siemens Healthineers DCA Vantage
- Roche cobas b 101
- EKF Diagnostics Quo-Test and Quo-Lab
- DiaSys InnovaStar
Questions, answered
Does the patient need to fast before a point-of-care HbA1c test?
No. Because HbA1c reflects average glucose over roughly the previous 8 to 12 weeks rather than the current level, no fasting or specific timing is needed, and the sample can be taken at any point during the visit.
Why is HbA1c reported in two different units (mmol/mol and %)?
mmol/mol is the IFCC reference unit used across the UK and much of Europe, while the percentage is the older NGSP/DCCT-aligned unit still common elsewhere. Many analysers and reports show both; they describe the same result on different scales and can be converted, so it is good practice to state the unit clearly to avoid confusion.
Can a point-of-care HbA1c result be used to diagnose diabetes?
Some POCT HbA1c systems are validated to recognised analytical performance standards and are used diagnostically within local protocols, but practice varies and quality assurance is essential. As an educational point only: diagnostic use, the need for confirmatory or laboratory testing, and how results are acted on should follow the operating service's policy and current clinical guidelines, not this record.