[Relationship between red blood cell parameters and hemoglobin A1c levels based on a retrospective evaluation of 10...

Introduction: Measurement of hemoglobin A1c (HbA1c) levels is commonly used to assess metabolic control in patients. However, several observations suggest that HbA1c levels are influenced by the severity and type of red cell abnormalities. Objective: In our work, we evaluated whether routinely requested red blood cell parameters should be considered in the interpretation of HbA1c levels in patients in general medical practice. Method: 60,225 patients with a single (first) HbA1c measurement and blood count from 2008 to 2018 were selected. We first assessed the distribution of HbA1c in discrete ranges of parameters. A multiple regression model was used to assess the relationship between red blood cell count (RBC), mean red blood cell size (MCV), hemoglobin (HB), hematocrit (HCT) and red blood cell size distribution (RDW). The effect size between parameters and HbA1c level was characterized by a coefficient of estimates (CE) based on a z-score transformation of the data. Estimation formulas were developed to characterize the combined effect of variables on HbA1c. Results: Age is the strongest determinant of HbA1c values. MCV in both genders, RDW in men and RBC in women showed a negative and positive relationship with HbA1c, respectively. Based on CE values, none of the parameters examined had a greater effect on HbA1c than age. The histograms of MCV, RDW, HB recorded in discrete ranges were identical. There was a large difference between the HbA1c values obtained with the estimating formula and the measured values. Discussion: Although some red blood cell parameters are significantly associated with HbA1c levels, this does not confer to a clinically significant effect. Conclusion: In routine clinical practice, except in cases with severe hematological abnormalities, MCV should not be considered when HbA1c is interpreted. Orv Hetil. 2024; 165(7): 243–248.