Alterations in HbA1c resulting from the donation of autologous blood for elective surgery in patients with diabetes mellitus.

Background: The aim of this study was to confirm the change in haemoglobin A1c consequent to pre-operative donation of autologous blood for elective surgery in patients with diabetes mellitus.
Material and Methods: For enrolment in this prospective study, patients had to be scheduled for multiple autologous blood donations at different times and have a haemoglobin A1c level more than 5.8% at the first donation. The values of four factors, haemoglobin, haemoglobin A1c, glycated albumin, and glycated albumin/haemoglobin A1c ratio were determined. Changes in the values of these four factors between before and after the blood donations were calculated.
Results: In all 24 patients studied, haemoglobin and haemoglobin A1c decreased as a result of the autologous blood donations. The group with a reduced glycated albumin/haemoglobin A1c ratio had short intervals between blood donations. Correlations were observed between donation interval and change in haemoglobin A1c (r=-0.63, P=0.003), and between donation interval and change in the glycated albumin/haemoglobin A1c ratio (r=0.489, P=0.045).
Discussion: Haemoglobin A1c levels are likely to be underestimated after autologous blood donation by patients with diabetes mellitus, so glycated albumin may be a better indicator of these patients' glycaemic control.