Labile glycated hemoglobin: an underestimated laboratory marker of short term glycemia.

Abstract

Diabetes mellitus is a major public health problem. Hemoglobin A1c (HbA1c) is a key laboratory parameter in the management of diabetes patients. However, in diabetes monitoring, interpretation of HbA1c results is hampered by the important interindividual variation in red blood cell (RBC) life span. Furthermore, HbA1c only slowly responds to changes in glucose metabolism. Besides HbA1c, there exists a labile HbA1c fraction (l-HbA1c), exhibiting much faster kinetics. As both HbA1c and l-HbA1c are measured by modern standard chromatography, we explored the possibilities of using the l-HbA1c fraction for monitoring glycemia. l-HbA1c and HbA1c fractions were simultaneously assayed on a Tosoh G8 analyzer and expressed as %. l-HbA1c results were compared with serum glucose and HbA1c. Concomitantly, RBC distribution width (RDW) was determined on a Sysmex SN analyzer as a marker for erythrocyte life span. l-HbA1c could be measured with between-run coefficient of variations (CVs) between 2.2 and 2.3%. l-HbA1c correlated with both glycemia (r=0.80) and HbA1c results (r=0.73). In a multiple regression model (r2=0.752), glycemia and HbA1c were the most determining factors. To a lesser extent, RDW correlated with l-HbA1c (r=0.158). Furthermore, the l-HbA1c/HbA1c ratio weakly positively correlated with RDW (r=0.247). L-HBA1c represents an additional marker for monitoring the rapid occurrence of glycemic disorders that escape detection when using only HbA1c and blood glucose. RDW can be used as an indicator of atypical RBCs life span, in which the l-HbA1c fraction may be helpful.