Measurement Uncertainty of HbA1c and Glucose Parameters, Which Are Diabetes Mellitus Diagnostic Tests

Objective: In this study, it was aimed to calculate the measurement uncertainties of HbA1c and glucose parameters, which have important roles in the diagnosis and treatment of diabetes, and to evaluate the possible effects of these uncertainty values on clinical decision limits.
Methods: The measurement uncertainties of HbA1c and glucose tests were calculated according to ISO/TS 20914 guidelines. In 2022, the results of patients in whom HbA1c and glucose were ordered simultaneously were retrospectively analysed and the results were evaluated according to measurement uncertainty.
Results: The calculated measurement uncertainty values of HbA1c and glucose tests were 2.41% and 7.92% for level 1 and 1.37% and 7.68% for level 2, respectively. When the HbA1c results of the patients were evaluated according to the measurement uncertainty calculated for level 1 and level 2, 2493 (8.1%) and 1845 (5.9%) were in the grey zone according to negative uncertainty and 2816 (9.1%) and 2120 (6.9%) were in the grey zone according to positive uncertainty, respectively. When glucose results were evaluated according to negative and positive uncertainty at both levels, 3959 (12.8%) and 5934 (19.2%) patients were in the grey zone, respectively.
Conclusion: In our laboratory, uncertainty values calculated for the HbA1c parameter were below the TEa% values determined by all three international organizations. Although the uncertainty of the glucose test was below the CLIA and rilibak TEa% values, it was found to be higher than the BV TEa% value. It should be kept in mind that measurement uncertainty in values at medical decision levels may affect the diagnosis and treatment of DM.