Glycated haemoglobin (HbA1c)
| Category | Biochemistry |
|---|---|
| Test background |
Glycation of proteins is the weighted mean proportional to the mean glucose concentration over the lifespan of the red blood cell. |
| Clinical Indications |
Diagnosis and monitoring of treatment of diabetes mellitus. |
| Reference range | 20-41 mmol/mol haemoglobin |
| Sample & container required | 4 mL EDTA (lavender top) Please send separate tubes for FBC, ESR and HBA1C |
| Sample volume | 1 mL |
| Turnaround time | 3 days. |
| Notes | HbA1c is accepted for the diagnosis of type 2 diabetes in the UK, but should not be used to diagnose type 1 diabetes or in the following contexts; childhood, pregnancy, renal failure, haemoglobinopathy trait, anaemia, HIV, abnormal red cell turnover, or any recent drug treatment likely to affect glycaemia or red-cell turnover. Type 2 diabetes diagnosis WHO: ≥48 mmol/mol with second indicator (either symptomatic or laboratory). Type 2 diabetes mellitus NICE CG66 treatment target 48-59 mmol/mol. Type 1 DM: NICE CG15 treatment target HbA1c ≤59 mmol/mol without frequent disabling hypoglycaemia; consider ≤48 mmol/mol where there is high arterial risk. Our laboratory was an early adopter of IFCC traceable HbA1c measurement and its use in the diagnosis of diabetes (see our 2011 Lancet article entitled “HbA1c; an old friend in new clothes”). We have also published our experience of the impact of the presence of haemoglobin variants on HbA1c interpretation. Our laboratory uses ion exchange chromatography to assess IFCC-traceable HbA1c; the detection of any of the >1,000 variant haemoglobins which may affect result interpretation is reported back to the test requestor. For more information on difficult cases, contact Dr Shivani Misra or Sophie Barnes.
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