HbA1c

and Eva Rudolf-Müller, doctor

Eva Rudolf-Müller is a freelance writer in the medical team. She studied human medicine and newspaper sciences and has repeatedly worked in both areas - as a doctor in the clinic, as a reviewer, and as a medical journalist for various specialist journals. She is currently working in online journalism, where a wide range of medicine is offered to everyone.

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The so-called HbA1c is a subtype of the hemoglobin of adults (HbA). HbA1c levels are used to determine the average sugar level in the blood of diabetics. Since it allows conclusions to be drawn about blood sugar concentrations over a longer period of time, HbA1c is also known colloquially as blood sugar memory. Read here how the HbA1c is formed, which values ​​are normal and what they mean for a diabetic.

What is HbA1c and how is it made?

Hemoglobin is the red pigment in the blood and enables oxygen and carbon dioxide to be transported around the body. There are different types of hemoglobin, with normal adult hemoglobin being called HbA.

If a sugar particle in the blood binds to the hemoglobin, this is known as glycation. Glycated, ie “saccharified” hemoglobin is given the addition 1 (HbA1) in the name. Most of these sugar deposits depend on a certain subunit of hemoglobin - this is expressed by the addition of c (HbA1c). If our blood sugar level is quite high, naturally more sugar particles bind to the hemoglobin; if the sugar level falls, the particles dissolve again.

However, a patient with diabetes has long-term elevated blood sugar levels. This makes the bond between sugar and hemoglobin firm and permanent. It persists until the red blood cells are broken down at the end of their life. This is the case after about three months. The HbA1c value provides information about how high the sugar concentration was on average in the patient's blood over the last few weeks.

HbA1c: units of measurement

In Germany, hemoglobin A1c is usually given on laboratory results as a percentage of total hemoglobin.

However, a new procedure by the International Federation of Clinical Chemistry (IFCC) is now considered an international reference point: It gives the value in millimoles per mole of hemoglobin (mmol / mol Hb). The units of measurement can be converted into one another using a formula:

Hemoglobin A1c (IFCC) in mmol / mol Hb = (% HbA1c -2.15): 0.0915

HbA1c: reference values

A deviation from the HbA1c normal value in previously healthy people can be an indication of manifest or incipient diabetes. But it alone does not allow a reliable diagnosis. To do this, the doctor must carry out further tests (oral glucose tolerance test = oGTT, measurement of the fasting blood sugar).

HbA1c: table with normal and limit values

There are two different assessment guidelines here:

According to the St. Vincent Declaration, HbA1c values ​​are assessed as follows:

Percentage HbA1c	judgement
< 6,5 %	Diabetes well adjusted
6,5 - 7,5 %	Diabetes set moderately
> 7,5 %	Diabetes poorly controlled

According to the recommendation of the European Commission of Experts, however, the values ​​are assessed as follows:

Percentage HbA1c	judgement
< 6 %	no diabetic condition
6 - 7 %	almost normal glycemia
7 - 8%	Diabetes adjusted excellently
8 - 9 %	Diabetes controlled well
9 - 10 %	Diabetes adjusted satisfactorily
> 10 %	Diabetes poorly controlled

In children and adolescents with diabetes, the HbA1c should be below 7.5%. The exact target value is set individually for each patient.

HbA1c for follow-up

The tables of normal values ​​show that the blood value HbA1c not only helps to diagnose diabetes. Above all, it is used to monitor the progress of patients with known diabetes: HbA1c values ​​that are above the normal range indicate that the patient's blood sugar has been increased in the last 8 to 12 weeks. Common reasons for this are, for example, that the patient is not taking their medication as prescribed, the medication is incorrectly dosed, or the patient is eating incorrectly. Then it is imperative to act. Badly adjusted blood sugar levels increase the risk of a heart attack, for example.

False all-clear possible

If the HbA1c is normal, this does not automatically mean that the blood sugar level is good. A brief increase in blood sugar (less than four hours) does not affect HbA1c. It is quite possible that nerves and blood vessels have already been damaged by the high sugar without it being noticed in the laboratory results.

Tags:  diet Diseases Diagnosis