RAPID FLUCTUATIONS IN GLYCOHEMOGLOBIN (HEMOGLOBIN-ALC) RELATED TO ACUTE CHANGES IN GLUCOSE

Abstract

Since glycohemoglobin (Hb A1c) has been observed to change acutely, HbA1c was studied in human and monkey subjects to determine whether acute changes occurred with rapid changes in plasma glucose concentration. A marked increase in Hb A1c was observed over 2 days in a 3 1/2 yr old boy who developed steroid-induced diabetes mellitus. A significant fall in Hb A1c was observed over 7 days in a pregnant woman recovering from hyperglycemia and ketoacidosis. During marked acute hyperglycemia and its recovery, 3 normal rhesus monkeys were studied for changes in plasma glucose and Hb A1c over 1 day. Hb A1c more than doubled in each study by the time plasma glucose reached approximately 90 mM and then declined by 12 h. While maintained at their usual stable glucose concentrations, human and monkeys subjects showed little differences in Hb A1c levels for dialyzed and nondialyzed hemolysates. With acute changes in blood glucose, the dialysis for 48 h yielded lower Hb A1c values. Hb A1c increased when hemolysates were dialyzed against high glucose concentrations. The effect of dialysis in sample preparation may be an important factor in correlating Hb A1c with acute and chronic changes in glucose status.