Aims: Poor comparability between laboratory results may have a strong impact on clinical decisions. The aim of this study was to assess the quality of glucose and HbA1c measurements in a large cohort of laboratories in various countries, in order to evaluate whether the current state of these very basic laboratory examinations can be considered to be adequate with respect to the clinical needs in the management of glucose control in diabetic patients.
Methods: External quality assessment schemes and proficiency testing surveys performed in 2017 in several European and American laboratories were analyzed in order to estimate the percentage of laboratories reaching the desired quality criteria based on the allowable total error in accordance with various international recommendations.
Results: In 2017 more than 95% of laboratories met the allowable total error for measuring HbA1c, and 92-94% of the studied laboratories met the target for glucose measurement.
Conclusions: The analytical quality for measuring glycated hemoglobin and glucose at laboratory level is generally acceptable, and accreditation to the ISO 15189:2012 standard is a robust guarantee that the laboratory meets the required criteria of acceptability. Several pre-analytical factors which may explain the discrepancies between the measured HbA1c and that estimated from other indicators of glucose control have to be taken into account, by focusing more on the pre-analytical than the analytical phase. In the case of glucose, special attention should be paid to the use of the correct anticoagulant, in order to avoid false negative results.
Keywords: Bias; Commutability; Control materials; EQAS; Glycated hemoglobin; Total error.