Characteristics of labile HbA₁ in erythrocytes from normals and diabetics

Abstract

Incubation of erythrocytes from diabetic patients and non-diabetic persons in 0.15 mol/1 saline at 37°C was followed by a decrease in ion-exchange microcolumn determined HbA₁ only during the first 4 h. The fraction removed was denoted as labile HbA₁ and the remaining fraction as stable HbA₁. Incubation in saline overnight at 20°C did not completely remove the labile fraction. Incubation in saline overnight at 4°C yielded only a slight decrease in labile HbA₁. Incubation in saline containing various glucose concentrations (up to 100 mmol/1) produced increasing amounts of HbA₁ during the first 3–4 h after which an equilibrium was reached. In both normal and diabetic erythrocytes incubated for 3–4 h we found a linear relationship between changes in labile HbA₁ and glucose concentration. The degree of increase in labile HbA₁ was the same in normals and diabetics and not dependent on pre-existing normal or moderately increased stable HbA₁.

In the blood from non-diabetics (n = 30) labile HbA₁ was 0.5±0.3% (mean±SD) and in diabetics (n = 80) 1.6±0.8%. The correlation between labile HbA₁ and simultaneously determined blood glucose was r = 0.72.

Key-words:

• glucose concentration
• glycosylated haemoglobins
• in vitro
• ionexchange chromatography
• saline incubation
• stable HbA₁
• temperature dependence
• time dependence