"HbA1" and "HbA1c" - what is it?
The daily determination of blood sugar or of urine sugar is just a snapshot. It is dependent on the time of day, the drugs and especially food.
How can you and your doctor but estimate the quality of your blood sugar control?
The measurement of HbA1c value will help here.
"Hb" stands for hemoglobin
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The Red Seal is called hemoglobin, in short "Hb". He is part of red blood cells and carries oxygen. Man has four subgroups of hemoglobin: HbA0, HbA1, HbA2 and HbF (see left chart).
The memory of the blood sugar control
A sugar particles stored at at HbA0, HbA1\/HbA1c is created.
One can speak of a "saccharification" haemoglobin. Blood sugar is higher, the more sugar particles on hemoglobin store itself, so the HbA1 and the HbA1c values increases. A high proportion of HbA1c speaks for high sugar levels, so a bad sugar treatment.
The life of a red Blutkörperchens and the Red Blutfarbstoffs hemoglobin is usually 3 months. The HbA1c value that reflects the average blood sugar control in the last 3 months. Therefore one speaks also of "Memory of the glucose control".
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For example:
If a Republicano is over two and a half months good set, has the day before the inspection appointment with his doctor but poor glucose levels, its HbA1c will be good because the average blood glucose levels over the longest time were across good.
If a Republicano for months has bad values, fast a few days before his visit to the doctor but or eats nothing, his current blood glucose value may be very good. The HbA1c will be but high. As a measure of the average blood glucose levels over the past 3 months, he reliably reflects the bad attitude.
It is recommended to measure the HbA1c every 3 months. He is one of the values entered in the health diabetes.
The value is determined directly in many physicians in practice. The result can then be discussed. To determine, a small drop of blood is sufficient, as he usually already obtained for the determination of blood sugar.
With the following table, you can derive your average blood sugar of the last three months of the HbA1c
What is a more desirable HbA1c value?
At the time, the practices in addition to the guidelines of the DDG focus according to the guidelines of AWMF. Shown in the following table. They are valid for type 2 diabetics.
Good EinstellungGrenzwertige EinstellungZu high setting
NBZ (mg/dl) | Gute Einstellung | Grenzwertige Einstellung | Zu hohe Einstellung |
80 - 120 | 111 - 140 | > 140 |
HbA1c % | < 6,5 | 6,5 - 7,5 | > 7,5 |
NBZ: Fasting blood glucose |
Source: DDG practice guideline: treatment of diabetes mellitus type 2% 2007
Applies to type 1 diabetes:
Therapeutic targets for patients with diabetes mellitus type 1 | ||
Outcome | Surrogate-Parameter | Individual therapy target |
Prevention of mikroangiopathischer and neuropathic complications | HbA1c | < 7,0% [= 1,2% [above the upper normal value] |
Source: DDG practice guideline: treatment of diabetes mellitus type 2% 2007
Formula:
Durchschnittlicher Blutzuckerspiegel (in mg/dl) = 33,3 x HbA1c (%) - 86 |
Source: Nathan d.m. et al., New England Journal of medicine, 1984
The risk of consequential damage is reduced...
Many studies show that high blood glucose levels over long periods of time with high HbA1c values result in damage to the eye, nerves and kidneys. If we manage to reduce the HbA1c, the risk for this damage is reduced on the other hand: for example, A large English study showed that with a lowering of HbA1c by 1% decreases the risk of damage to the eye and kidney by a third!
The HbA1c is certainly not the only important value. He must be properly classified and evaluated.
... but only with proper handling
Constantly to low glucose levels (frequent hypoglycaemia) cause a good HbA1c value. The setting is then but still bad, or even dangerous!
Strongly changing blood sugar with very high and very low values can also pretend a satisfactory result in the funds.
The life span of red blood cells plays a role as described above: in very short or long life (some forms of anemia) will be the HbA1c according to wrong, too low or too high.
A large American investigation with type 1 diabetes patients revealed that it is dramatically on the handling form: same HbA1c value can become according to treatment differently often!
Ask your consultant or your GP, which deals mainly with diabetes patients.
HbA1c receives new world reference standard
A new reference standard commits laboratories, clinics and established practices, the values for the glucose-binding Red Seal, the so-called glykierte hemoglobin, to specify in a new unity. This new standard is used internationally.
HbA1c measurement conversions
Still no entry is made! | |
Old unit [%]: | |
New unit [mmol/mol]: | |
Glykierte hemoglobin in the blood is the most telling measure of the qualitative assessment of a patient's blood sugar control, based on the last 8 to 12 weeks.
Since publication of a study (DCCT study, diabetes control and complication trial), the measurement of a specific sub group of glykierten hemoglobin, HbA1c value is standard in diabetes management. The HbA1c value in a patient with type I diabetes is low, this is associated with a reduced risk for microvascular damage. As well, the risk of macro-vascular complications, such as for example the diabetic retinopathy, is less in the long term in this case.
Another clinical study led to similar results (United Kingdom prospective diabetes study, short UKPDS). It compares the effects of the various forms of therapy in diabetes mellitus type 2 and evaluates. The study shows that the type II diabetes is a higher HbA1c value directly linked to a higher risk of diabetes-related long-term complications.
Professional societies have recommended target values for the HbA1c individually but are set when any diabetes patients. Typically an HbA1c value is striving in the diabetes 2 of less than 7%. In addition to this orientation is related to the individual patient, the HbA1c delivers a measure (benchmark) the comparison of different diabetes centres.
HbA1c is the advantage of international comparability
Since 1996, is with the national Glycohemoglobin standardization program (NGSP) a framework for HbA1c and enables the international comparability of analysis results. This standardization led to the calibration of HbA1c - despite critical review.
Analysis system on the market after NGSP. The comparability of the analysis values achieved by NGSP presented a so-called consensus standard, gave up an international standard with higher levels of reliability.
To close this reliability gap where possible, the International Federation for clinical chemistry (IFCC) established a working group should draw up an international standard for HbA1c. This new standard should be traceable and more accurate. The IFCC made the observation that she contaminated separated up, crucial for the determination of HbA1c group with other components of hemoglobin in HPCL (Hochdruckflüssigkeitschromatografie) and this was inaccurate on the old NGSP standard.
Reference preparation includes HbA0 and HbA1c
A combination of HbA0 and HbA1c is the new reference preparation. The reference measurement methods consists of a HPLC, which is coupled with mass spectrometry (LC-MS \/ MS). Comparative measurements between the reference laboratories ever undertaken by an international group of laboratories to monitor the reliability of the measurement procedure. International Diabetes organizations signal now with a common consensus statement to the new standardization of HbA1c, a worldwide transition to the new HbA1c standard is required.
All quantitative studies in medical laboratories are subject to the new directive of the Federal Medical Association (System) for quantitative laboratory medical research since 2008 of internal quality control quality assurance. Analytes that are listed in the directive in the plants 1 a d or B 1 a-c, are covered by the external quality control (schemes). You will be evaluated since 1 January 2009 after the grade boundaries of the new directive. Since entry into force of the new directive for quality assurance at 2008, there is a transition period of 2 years, where internal quality control must also be converted.
Based on an improved international reference measurement methods external quality control has been changed from HbA1c on 01.01.2009 the new unit, and click new grade boundaries.
What hospitals, physician practices and laboratories need to do
Clinics, medical practices and medical laboratories have as a result of the conversion of the internal and external quality control to introduce their internal quality control until at the latest to 31.03.2010 according to the table B 1 of the directive of the system with the new unit and the new grade boundaries. This associated revised indicative numerical decision boundaries for metabolic control of diabetic patients. Medical laboratories are encouraged to adapt their internal quality control in accordance with the manufacturers of equipment and reagents to the end of the transitional period at the 31.03.2010 to the new HbA1c unit mmol\/mol (HbA0 HbA1c).
The formula to convert the percentageis of HbA1c in HbA1c mmol\/mol (HbA0 HbA1c):
HbA1c [mmol/mol] = (10 * HbA1c [%] - 21.52) / 0.9148
Since the external quality control (schemes) have been converted on 01.01.2009 in Germany to the new Reverenz unit, the ring test organizations assess the experiments on this new basis. The first attempt in January 2009 showed that nearly 60% of the participating laboratories using already the new unit of value for the results of HbA1c. At the remaining laboratories, which gave the Hba1c in the previous percentage (NGSP) values, the ring test organization was to subsequently the percentages in the new unit "mmol\/mol". Prior consent of the competent Advisory Board of the system this technique was provided a transition period of six months.
In the this first scheme 90% of the laboratories achieved approximately two sent samples an accurate result.
Support for the transition to the new unit and the new grade boundaries are patients converter on the Internet available (see above). We recommend all laboratories and doctors to specify up to further the results of the HbA1c measurement in the old (per cent) and in the new unit (mmol\/mol).
The IFCC calibration and the new unit to worldwide be converted. Britain wants to introduce also them from 01.06.2009 with a transitional period.
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