Mechanism and speed of reactions between haemoglobin and glucose consequences for the measurement of glycosylated haemoglobins in patient material.

Abstract The mechanism of the reactions between haemoglobin and glucose in the erythrocyte was investigated in vitro using 14 C-labelled glucose. Reaction speed constants were found for the formation of HbA 1c (4.2 · 10 −3 ) and the formation and degradation of the Schiff Base (9.22 · 10 −4 and 0.435, respectively) for concentrations in mmol/1 and time in hours at 37°C. An equilibrium constant of 2.12 · 10 −3 was found for the reversible formation of the Schiff Base. The results were included in a mathematical model with which a number of clinically relevant situations were simulated. From the results the conclusion was drawn that during the measurement of fast haemoglobins, the intermediate Schiff Base causes a variation dependent on the glucose concentration at the moment of blood sampling. The model demonstrates that this disturbance can be eliminated by incubating erythrocytes with physiological saline for 10 h at 37°C.