[Comparison of various methods for determining glycosylated hemoglobins]

Determination of glycosilated haemoglobin (HbA1) has become an important parameter for the control of diabetes mellitus. Although several methods are available today, some are time consuming and complicated and may lead to differing results. Two methods, the thiobarbituric-acid (TBA) method and microcolumn chromatography, were compared with the reference method, high performance liquid chromatography (HPLC), with respect to precision, accuracy and practicability. Seventy different blood samples from diabetics were analysed. Using the TBA method, good results were achieved which were generally consistent with those of the reference method (r = 0.90); there were no significant differences in values determined with the two methods. However, the TBA method requires an inordinate amount of work. Microcolumn chromatography is better suited to the needs of physicians in private practice. Results with this method also correlate well with those of the reference method (r = 0.92) when the labile aldimine fraction has been removed by dialysis of the sample. Quality control can be performed using either lyophilized or deep-frozen control samples.