Association of variation range in glycated albumin (GA) with increase but not decrease in plasma glucose: implication for the mechanism by which GA reflects glycemic excursion.

OBJECTIVES: HbA1c mainly reflects mean plasma glucose (PG), whereas glycated albumin (GA) reflects glycemic excursion in addition to mean PG; the mechanism of the difference between HbA1c and GA is unknown. We hypothesized that a transient increase in PG irreversibly produces stable GA unlike HbA1c. To prove this hypothesis, we investigated diurnal variations in PG, HbA1c, #C fraction (a fraction containing unstable HbA1c and modified hemoglobin on HPLC) and GA in diabetic patients.

DESIGN AND METHODS: Sixteen diabetic patients with poor glycemic control were enrolled in this study. Blood sampling was performed before and after each meal, before bedtime, and before breakfast on the following day; PG, HbA1c, #C fraction, and GA were measured. The variations of these indicators were compared with those in PG.

RESULTS: HbA1c showed almost no change regardless of diurnal glycemic variation. Variation range in #C fraction significantly correlated with variation range in PG when PG increased (R=0.746, p<0.0001) and decreased (R=0.271, p=0.035). On the other hand, variation range in GA significantly correlated with variation range in PG when PG increased (R=0.322, p=0.021), but not when PG decreased (R=0.090, p=0.493).

CONCLUSIONS: We observed that variation range in GA significantly correlated with variation range in PG when PG increased but not when PG decreased for the first time. It is considered that GA reflects glycemic excursion through this phenomenon.