Clinical importance of the reversible fraction of haemoglobin A1c in Type 2 (non-insulin-dependent) diabetes.

Two studies demonstrating the clinical relevance of the labile fraction of haemoglobin A1c are presented. Haemolysates, dialysed at 37 degrees C against 0.9% NaCl, showed an average decrease of haemoglobin A1c value of 7.0% of total glycosylated haemoglobin, post-dialysis. There was a close correlation between the pre- and post-dialysis haemoglobin A1c values (r = 0.9644). In four Type 2 (non-insulin-dependent) diabetic subjects, blood glucose and pre- and post-dialysis haemoglobin A1c values were determined at weekly intervals over an 18-week period, including 6 weeks when oral hypoglycaemic therapy was withheld. During this time, pre- and post-dialysis haemoglobin A1c values responded synchronously to changes in blood glucose concentration. The mean coefficient of variation of the pre- and post-dialysis haemoglobin A1c values did not differ significantly over the 18-week period. It is concluded that the routine elimination of the labile fraction of haemoglobin A1c is not necessary to assess control in Type 2 diabetes.