ESTIMATION OF PLASMA-GLUCOSE FLUCTUATION WITH A COMBINATION TEST OF HEMOGLOBIN A1C AND 1,5-ANHYDROGLUCITOL

We investigated the effect of plasma glucose fluctuation on hemoglobin A1c (HbA1c) and plasma 1,5-anhydroglucitol (AG) levels, especially in insulin-dependent diabetes mellitus (IDDM). Plasma AG is a new marker that provides sensitive and analytical information on glycemic control. The basic mechanisms underlying both the reduction and recovery of the plasma AG level, ie, the excretion into urine with glucosuria and the amount supplied to the body, were presumed to be similar in IDDM and non-insulin-dependent diabetes mellitus (NIDDM) patients. The correlation coefficient for mean plasma glucose and AG was -.591, and it was .578 for mean plasma glucose and HbA1c in IDDM patients. In NIDDM, the correlation between mean plasma glucose and AG was -.869, and between mean plasma glucose and HbA1c, .875. The plasma AG levels in the IDDM group showed a lower range than in the NIDDM group, even with similar HbA1c levels. All the cases showing lower plasma AG levels among those with similar HbA1c levels manifested greater fluctuation of plasma glucose and a larger amount of urinary glucose. The lower AG level in IDDM patients was reversible to the level in NIDDM patients when the greater fluctuation of plasma glucose was corrected. Thus, it was suggested that because urinary glucose excretion is intermittently high in IDDM patients, plasma AG is frequently low, even though the mean plasma glucose and HbA1c levels suggest good control. The results of the present study indicate the significance of both plasma glucose fluctuation and mean plasma glucose level for an evaluation of glycemic control, especially in IDDM patients, and imply the danger of frequent hypoglycemia if the improvement of glycemic control is evaluated by HbA1c alone. © 1992.