Analysis index

1 ml EDTA-blood (Stability in EDTA-blood at 4°C – 8°C: max. 3 – 4 days, however for accuracy, testing should be done within 24 hours after blood taking)

< 5,7 % (3,9 mmol/mol): no diabetes
5,7 % – 6,4 % (39 – 48 mmol/mol): gray area; evaluation of fasting glucose or OGTT
≥ 6,5 % (> 48 mmol/mol): diabetes mellitus

Suspicion of diabetes mellitus, documentation of preceding metabolism situation in outpatient or inpatient diabetes regimens. Monitoring of the metabolism in 12-weekly intervals.

HbA1c is a product of non-enzymatic glycosylation reaction from glucose and hemoglobin. The HbA1c value reflects the average glucose level over the past 2 – 3 months corresponding to the erythrocyte life span. Tests have revealed, that a 1 % HbA1c increase reflects an average increase of the plasma glucose level of 35 mg/dl. The relation between HbA1c and the mean blood glucose concentration is reflected by the following formula: mean blood glucose value = 36 x HbA1c – 100. The HbA1c value does not say anything about blood glucose fluctuations. A valid assessment of the HbA1c is not possible in case of:

1. Hemoglobin variants (HbS, HbE, HbF, HbC, HbD and others)
2. Conditions with increased or decreased erythrocyte life-span (hemolytic anemia, iron deficiency anemia, erythropoiesis under treatment for anemia, condition after splenectomy or illnesses of the spleen, liver or kidneys)
3. Uremia (carbamylated Hb), high-dose long term therapy with acetylic salicylic acid (acetylated Hb)
4. Inhibition of the glycation (e.g. long term therapy with ascorbic acid or vitamin E). The clinical significance of this phenomenon is not very well researched, though.
5. Pregnancy
6. Ethnicity and age (HbA1c increased with age; hence a potential age-oriented adjustment of the diagnostic criteria needs to be discussed and evaluated. It is also discussed, which potential role alternative parameters such as fructosamine or glycated albumin may play.