HbA1 determination by agar gel electrophoresis after elimination of labile HbA1: a comparison with ion-exchange chromatography.

A rapid and simple method, Agar gel electrophoresis (GlytracTM, Corning Medical), for HbA1 analysis was evaluated and compared with an ion-exchange chromatography method capable of estimating HbA1 (a+b) and HbA1c separately. Preincubated samples from diabetics and normals were analysed by both methods and showed good correlation (r=0.97, n=89). The following data were obtained with agar gel electrophoresis. Incubation of erythrocytes at a glucose concentration of 30 mmol/l for 6 h at 37 degrees C gave an increase of 1.39% HbA1. This increase was almost reversed by reincubation in low glucose medium. By preincubation of erythrocytes in saline HbA1 decreased 0.90 +/- 0.39% HbA1 (mean +/- SD) in diabetics and 0.38 +/- 0.26% HbA1 in normal controls. This preincubation step is necessary to eliminate the labile HbA1 fraction when HbA1 is to be used as an index of long term glucose control in diabetes. The HbA1 ranged from 5.1 to 7.4% (n=68), mean 5.8% (SD 0.5). HbA1 in patients with juvenile diabetes ranged from 6.1 to 19.3%. Within-run precision (CV) was 2.3 and 2.5% in normal and diabetic samples, respectively. Between-run precision was 5.7%. Variation in temperature between 18.5 and 31.5 degrees C did not affect the HbA1 values significantly. Within-run and between-run precision for chromatography was 3.4 and 4.7% respectively. Agar gel electrophoresis is a simple and rapid method for HbA1 determination, with acceptable precision and accuracy.