The HbA1c value (long-term blood sugar value)

Definition – What is the HbA1c value?

The HbA1c value plays an important role in the diagnosis and therapy of diabetes mellitus. Ultimately, this is the normal red blood pigment haemoglobin (HbA), to which glucose is attached. This attachment, known chemically as glycation, occurs spontaneously and depends on the level of blood sugar, i.e. the glucose concentration in the blood.

The higher this is, the more hemoglobin is glycated to HbA1c. The HbA1c value thus indicates the proportion of HbA1c in the total hemoglobin. Since thed hemoglobin is only broken down after 8-12 weeks, the proportion of HbA1c indicates how high the blood sugar was in the last 2-3 months. The higher this was, the higher the HbA1c value is, which is why it is also called “blood sugar memory” or “long-term blood sugar” and is very suitable for follow-ups in diabetes therapy. It is also becoming increasingly important in the diagnosis of diabetes mellitus.

When is the HbA1c value determined?

HbA1c plays a central role in blood glucose control in patients with diabetes mellitus type II, as it is a prognostic factor for late sequelae such as vascular and nerve damage. Compared to the normal blood glucose value, the value has the advantage that it is less subject to daily or diurnal fluctuations and even a short-term fasting of the patient shortly before control has no great influence. Therefore, it is very well suited to monitor the course of therapy for diabetes mellitus.

It is not determined daily, but usually every 3 months, so that the doctor can assess the effects of the therapy and adjust it if necessary. In diabetes mellitus type II, the goal is to keep the HbA1c between 6.5% and 7.5% in order to prevent late complications. The HbA1c can also be used to diagnose diabetes mellitus: If it is above 6.5%, the diagnosis can be made; if it is above 6.0%, this can additionally support a suspicion that has arisen, for example, due to typical symptoms.

If it is below 5.7%, diabetes mellitus is very unlikely. However, if the value is between 5.7-6.5%, diabetes mellitus cannot be ruled out and an oral glucose tolerance test (oGTT) must be performed if the disease is suspected. You can find more information on diagnostics and therapy under Diabetes mellitus