Estimation of HbA1c Levels in Transfusion-Dependent Thalassemia Patients in Comparison With Normal Healthy Individuals

Introduction HbA1c values used for diagnosing and treating diabetes can be affected by factors such as red blood cell lifespan, hemolysis, red cell transfusion, and the presence of minor Hb species like HbA2 and HBF in hemoglobinopathies like sickle cell disease, homozygous HbC disease, HbSC disease, and β-thalassemia. This study aims to compare HbA1c levels in transfusion-dependent thalassemia (TDT) patients and healthy individuals. Materials and methods This is a cross-sectional comparative study. This study comprises two population groups. The first group includes 35 TDT patients and the second group consists of 35 non-thalassemic individuals who were matched for age (±1 year), gender, and BMI (±1 kg/m²). The patients were selected from the pediatric outpatient department (OPD), thalassemia ward in the pediatric department, and medicine OPD. Written informed consent/assent was obtained from the participants. A 3 ml fasting venous blood sample for fasting blood sugar (FBS), HbA1c, and complete blood count (CBC) values was obtained in ethylenediaminetetraacetic acid (EDTA) vials on the scheduled blood transfusion day (pretransfusion samples). Samples were then sent to an in-house accredited lab for testing and analysis. HbA1c was performed using the high-performance liquid chromatography (HPLC) technique. Data was compared using a t-test. Qualitative parameters were compared between groups by X² square analyses. A multivariate linear regression model was used to explore the independent contribution of an individual predictor to HbA1c variability. Results In the study, 85.7% of patients with TDT had HbA1c levels in the diabetic range (>6.4%). In comparison, none of the control group patients had HbA1c values in the diabetic range. The mean HbA1c level was 6.94% in TDT cases and 5.3% in the control group, which was statistically significant (p < 0.001). Elevated FBS levels in the prediabetic range (>100 mg/dl, <126mg/dl) were observed in 25.7% TDT cases. All 35 controls had normal FBS levels (<100 mg/dl). No significant difference was found in FBS levels between cases (92.97 (±9.141) mg/dL) and controls (89.20 (±7.584) mg/dL) (p = 0.065). However moderately positive correlation exists between FBS and HbA1C (r =.470, p = 0.004) and between age and HbA1C (r = 0.335, p = 0.049). Conclusions The use of HbA1c as a screening tool for diabetes mellitus (DM) or assessment of glycemic control is inappropriate in TDT patients. The levels could be falsely elevated, as we found out in our study. In conditions where there is a mismatch between HbA1c and FBS levels, as seen in TDT patients, plasma glucose criteria should be used to diagnose diabetes. It is advised to use alternative indices such as fructosamine levels, glycated albumin, and continuous glucose monitoring.