Abstract
Specimens of HbA1c from human hemolysate contain more than six minor components which cannot be separated by conventional methods. These components have differing characteristic properties and their levels fluctuate depending on the time the blood is drawn and the method of sample preparation used. HbA1c exhibits unreasonable fluctuation and unexpectedly high levels and is therefore not an accurate indicator of long-term blood glucose control. The six components of HbA1c were resolved by our new chromatographic technique using IEX-530, and designated by their eluting position and properties; HbF6, L-GHb7, St-GHb8, L-GHb9, FrlO, and Frll. HbF6 was alkaline resistant. L-GHb7 and L-GHg9 were easily removed by treatment with saline or semicarbazide and increased after incubation with glucose. The level of L-GHb7 in the blood showed rapid and varied fluctuation on OGTT in both diabetics and control subjects. More than 2% HbF6 and L-GHb7 was present in 13.3% of the control group (n=57) and in 51.4% of the IDDM group (n=45). St-GHb8, which was a major component of HbA1c, was not affected by pretreatment with saline, semicarbazide or glucose in vitro. The level of St-GHb8 in the blood showed little change on OGTT. HbA1c, hitherto referred to as one stable component, is an incorrect term used to denote the index of long-term blood glucose control. It is important and warranted to use the level of stable glycohemoglobin (St-GHb8) in future determinations following proper analytical methods.
