Haemoglobinopathies, malaria, and other interferences with HBA1 assessment

Total glycosylated haemoglobin (HbA1) was determined by a rapid minicolumn chromatography technique in 438 diabetic patients and correlated with the mean of fasting and post-prandial blood glucose values for the preceding six weeks. In 360 of them, free of congenital haemoglobinopathies and other detected causes of HbA1 mis-interpretation (reference group), a significant correlation was established between the HbA1 and glucose values: y = 0.54 X + 4.91; r = 791; (p less than 0.01). In 28 of the 29 patients with heterozygous haemoglobinopathies (Hb S = 17; Hb C = 8; Hb D Pundjab = 1; Hb E = 2) the apparent HbA1 values were inappropriately low. The apparent HbA1 value was above the 95% confidence limits in the 29th patient, with beta thalassaemia. In 10 out of 14 diabetics with recurrent hypoglycemic attacks, the HbA1 value was lower than the 95% confidence limits of expected values. Out of 21 diabetics with a shortened red cell lifespan (occult blood losses: 10; haemolysis: 11) 15 displayed a lower than expected HbA1 value. Among these was a diabetic patient with malaria and severe anaemia. Out of 14 diabetics with severe chronic renal failure only 3 presented with apparent HbA1 values above the 95% confidence limits.