Whole Blood Donation Affects the Interpretation of Hemoglobin A1c.

Introduction: Several factors, including changed dynamics of erythrocyte formation and degradation, can influence the degree of hemoglobin A_1c (HbA_1c) formation thereby affecting its use in monitoring diabetes. This study determines the influence of whole blood donation on HbA_1c in both non-diabetic blood donors and blood donors with type 2 diabetes. Methods: In this observational study, 23 non-diabetic blood donors and 21 blood donors with type 2 diabetes donated 475 mL whole blood and were followed prospectively for nine weeks. Each week blood samples were collected and analyzed for changes in HbA_1c using three secondary reference measurement procedures. Results: Twelve non-diabetic blood donors (52.2%) and 10 (58.8%) blood donors with type 2 diabetes had a significant reduction in HbA_1c following blood donation (reduction >-4.28%, P < 0.05). All non-diabetic blood donors with a normal ferritin concentration predonation had a significant reduction in HbA_1c. In the non-diabetic group the maximum reduction was -11.9%, in the type 2 diabetes group -12.0%. When eligible to donate again, 52.2% of the non-diabetic blood donors and 41.2% of the blood donors with type 2 diabetes had HbA_1c concentrations significantly lower compared to their predonation concentration (reduction >-4.28%, P < 0.05). Conclusion: Patients with type 2 diabetes contributing to whole blood donation programs can be at risk of falsely lowered HbA_1c. This could lead to a wrong interpretation of their glycemic control by their general practitioner or internist. [ABSTRACT FROM AUTHOR]