Fetal hemoglobin and hemoglobin A1c level among pediatric patients with type 1 diabetes.

INTRODUCTION Glycated hemoglobin (HbA1c) is used as a cumulative estimate of mean blood glucose levels from the preceding 5-12 weeks. This is the gold standard in assessing glycemic control in patients with diabetes. The ADA criteria for the diagnosis of diabetes, including HbA1c level, contribute to the importance of recognizing any variation pertaining to the HbA1c measurement. HbA1c is often used as a primary endpoint in the interventional studies among patients with diabetes. Thus, knowledge about factors independently to glycemia, affecting HbA1c is clinically useful. AIM OF STUDY Evaluation variability of fetal hemoglobin (HbF) level among Polish children with diabetes and how it may affect the HbA1c level measurement. MATERIAL AND METHODS This was a prospective cohort study. A laboratory HbA1c testing was performed for more than 96% of pediatric diabetic patients in the region. In our study we included all consecutive patients aged 2 to 18 years with type 1 diabetes (T1D) and the disease duration longer than one year (555 patients). All patients had HbA1c and HbF measured at three time-points during minimum one-year period. In the same time, clinical data were recorded. The measurements of HbA1c and HbF were performed by means of cation-exchange high-pressure liquid chromatography (HPLC) on a D-10 Dual A2/F/A1c (Bio-Rad Laboratories, Hercules, CA, USA). Statistical analysis was performed using the Statistica 10.0 package (StatSoft, Tulsa, USA). RESULTS An average age in the observed group was 12.9±3.8 years, diabetes duration 5.6±3.4 years, HbA1c was 7.59±1.33% (59±10.65 mmol/mol). In 78 (14%) patients elevated levels of HbF (>0.8%) were found at each time-point, mean value 1.2±0.45%. Elevated HbF was associated with younger age at examination (p=0.03) and younger age of diagnosis (p=0.01). It was not related to diabetes duration (p=0.21). No correlation between HbA1c and HbF was observed in the study (R=-0.09; p=0.43). CONCLUSIONS Fetal hemoglobin does not affect HbA1c measurement among pediatric patients with type 1 diabetes older that 2 years.