Diabetes Care, Vol 21, Issue 2 209-212, Copyright © 1998 by American Diabetes Association
Slicing the pie. Correlating HbA--values with average blood glucose values in a pie chart form
KW Brewer, HP Chase, S Owen and SK Garg
Department of Pediatrics, Barbara Davis Center for Childhood Diabetes, University of Colorado Health Sciences Center, Denver 80262, USA.
OBJECTIVE: The purpose of this study was to define the correlation between
HbA1c values and the percentage of home blood glucose (HBG) measurements
within given ranges in a pie chart in three age-groups of subjects with
type 1 diabetes. RESEARCH DESIGN AND METHODS: HbA1c values were compared
with HBG measurements in subjects who did at least three blood glucose
tests per day over 30 days in three age groups: 5-11, 12-16, and 17-35
years. The blood glucose values were arbitrarily divided into three groups,
defined as the percentage of HBG measurements within, above, and below
target range. Each range was then compared with the corresponding HbA1c
value. Longitudinal data were also collected for 279 of the subjects after
a mean of 139 days. RESULTS: A strong correlation (P = 0.001) was found
between HbA1c values and the average blood glucose, and also with the
percentage of HBG measurements within, above, and below target range in
each of the three age-groups (P < 0.001). Analyses of longitudinal data
showed a strong correlation of the changes in HbA1c values to the changes
in blood glucose values. CONCLUSIONS: These data showed that a pie-shaped
graph of the HBG data can be useful as a clinical parameter in helping
patients and families attain desired HbA1c values.