Reliability of HbA1 Assay in the Mass Survey for Diabetes Mellitus, with Special Reference to the Preservation and Transportation of Blood Samples

Studies on the reliability of the HbA1 assay in mass surveys for diabetes mellitus were carried out with special reference to the preservation and transportation of blood samples. It is essential to confirm that the preservation and transportation of samples have no effect on values for HbA1, since most of the mass surveys are carried out as field works. In our experience the levels of HbA1 remained unchanged for one week, both in samples kept at 4°C, and in frozen samples kept at -40°C or -80°C and transported on solid CO2. The levels of HbA1 in the samples transported from Manila to Wakayama by the above-mentioned methods did not differ from those obtained in corresponding fresh samples. There was a good correlation between levels of HbA1 and levels of plasma glucose obtained 1 or 2hr after breakfast (PPG). It was concluded that the use of both criteria (HbA1 of more than 8.00% and PPG of more than 120mg/ 100ml) in the diagnosis of diabetes mellitus is more reliable than use of either one alone.