Rapid and slow rate of decrease in HbA1a + b and HbA1c during improved glycaemic control.

The change in glycosylated haemoglobins was studied with a column chromatographic method when glycaemic control was rapidly improved in nine diabetic patients. The patients were followed for 3 weeks or more. There was a decrease in HbA1a+b and HbA1c within the first few days of improved control and this decrease was faster than later on. The initial decrease of HbA1a+b was faster than that of HbA1c. In individual patients the initial decrease in glycosylated haemoglobins correlated with the initial rate of decrease in blood glucose. It is concluded that HbA1a+b and HbA1c decrease biphasically during improved glycaemic control. The rapid initial decrease may be due to labile HbA1 and it is large enough to influence the value of HbA1 as an indicator of long-term glycaemic control in some patients.