Diabetes Care, Vol 21, Issue 10 1732-1735, Copyright © 1998 by American Diabetes Association
Abnormally decreased HbA1c can be assessed with erythrocyte creatine in patients with a shortened erythrocyte age
Y Jiao, T Okumiya, T Saibara, K Park and M Sasaki
Department of Laboratory Medicine, Kochi Medical School, Nankoku, Japan.
OBJECTIVE: To investigate whether erythrocyte creatine can serve as a
corrective index for HbA1c in patients with a shortened mean age of
erythrocytes. RESEARCH DESIGN AND METHODS: HbA1c and creatine in
density-fractionated erythrocytes from 18 normal subjects were measured.
HbA1c and erythrocyte creatine in the whole blood of 43 patients with liver
cirrhosis (LC), 14 patients with hemolytic anemia (HA), 38 other patients
with high reticulocyte counts (HRC) (>2.2%), and 59 normal subjects were
also measured. The patients in this study all had normal blood glucose
levels. A correction formula derived from the linear regression equation
for the correlation between HbA1c and erythrocyte creatine was used to
correct the patients' HbA1c values. RESULTS: Among density-fractionated
erythrocytes, the young cells exhibited low HbA1c and high creatine values.
With progressively increasing density, HbA1c gradually increased and
creatine gradually decreased. In the whole blood samples, the HbA1c values
were significantly lower (P < 0.001) in LC, HA, and HRC patients than in
normal subjects. By contrast, the erythrocyte creatine values were
significantly higher (P < 0.001) in LC, HA, and HRC patients than in
normal subjects. A linear correlation between HbA1c (y) and erythrocyte
creatine (x) was observed (y=-0.224x + 5.00; n=154; r=-0.70; P < 0.001).
Based on the regression equation, a correction formula was obtained. Low
HbA1c values (<4.3%) were found in 24 of the 43 LC patients, 12 of the
14 HA patients, and 20 of the 38 HRC patients. After correction of the
HbA1c values, 15 of the 24 LC patients, 9 of the 12 HA patients, and 16 of
the 20 HRC patients had HbA1c values within the normal range. CONCLUSIONS:
HbA1c decreased in inverse proportion to the increase in erythrocyte
creatine because of a shortened mean age of erythrocytes. The abnormally
decreased HbA1c value could be assessed with erythrocyte creatine.