Higher HbA1c Measurement Quality Standards are Needed for Follow-Up and Diagnosis: Experience and Analyses from Germany

Abstract

Measurement of HbA1c is an essential laboratory measure for the follow-up and therapy decision-making in patients with diabetes. HbA1c is one of the measurands in laboratory medicine that have to be successfully checked according to the criteria of the guidelines of the German Medical Association (Rili-BAEK) in external quality assurance using the reference method value concept, when applied in patient care. The allowed deviation of ±18% in external quality assessment (EQA) and ± 10% in internal quality control has been ultimately met by virtually all the different manufacturers and methods. However, such broad limits for permissible deviations are not suitable in view of medical requirements in patient care. The low-level acceptance criteria also depends on the previously used EQA materials used in Germany. In fact, HbA1c measurement results that are imprecisely measured or come from incorrectly calibrated devices are difficult to identify. With implementation of unprocessed fresh EDTA blood, the situation has changed. Until now systems with unit use reagents for point-of-care testing (POCT) of HbA1c are not mandatory to participate in EQA schemes in Germany. This paper outlines why there was a need to narrow the acceptance limits listed within the Rili-BAEK for HbA1c's internal (to ± 3%) and external (to ± 8%) quality controls in EQA schemes for Germany, which will take place after a transition period in the next years. Higher quality in HbA1c measurements will help to avoid misdiagnosis of diabetes as well as potential over- or undertreatment of patients at risk for diabetes.

Are all glucose solutions used for oGTT equal?

“…This parameter avoids many issues of the oGTT (single blood draw only, subjects must not be fasting); however, estimation of the HbA1c has its own issues. 24,25 Several studies have shown that the overlap between HbA1c and glucose-based diabetes diagnoses is low (e.g. 30% defined by both criteria).…”

“…However, it is not clear to which extent measurement of this parameter is truly used for diabetes diagnosis. This parameter avoids many issues of the oGTT (single blood draw only, subjects must not be fasting); however, estimation of the HbA1c has its own issues 24,25 . Several studies have shown that the overlap between HbA1c and glucose‐based diabetes diagnoses is low (e.g.…”

Systematic review and meta-analysis: influence of iron deficiency anemia on blood glycosylated hemoglobin in diabetic patients

“…The survival time of red blood cells in the human body is about 120 days, and HbA1c in the blood during erythropoiesis is maintained at a certain level, so the HbA1c can be 3 to 4 months before blood plasma glucose average, and the time of blood collection, blood collection state, and other factors, such as whether fasted or not has nothing to do with its reading, therefore, it can reflect the mean value of long-term plasma glucose in diabetic patients (34,35). The current detection methods of HbA1c can be divided into one item according to the difference in the structure of HbA1c, such as immunoassay, affinity chromatography, ion capture, and so on (36). At present, HbA1c is not only an observation index of mean plasma glucose in diabetic patients, but has also been used in the diagnosis of diabetes in European and American countries.…”

Critical Reappraisal of the Time-in-Range: Alternative or Useful Addition to Glycated Hemoglobin?

“…This is expected to lead to a further improvement in measurement quality. [10][11][12] HbA1c measurement can be used for diagnosing diabetes although it is not widely used as such. In practice, HbA1c is most often used to evaluate the level of glycemic control over longer periods of time; however, not all HbA1c measurements provide results that match the BG values measured by the patients themselves.…”