Objective: Since glycohemoglobin values are widely used clinically as a surrogate
for average glucose concentration over an extended period of time, we decided to determine
the actual relationship between 24-hour integrated glucose values and percent total
glycohemoglobin (%tGHb) in cohorts of people with and without diabetes. Research Design
and Methods: In 48 people without known diabetes with known stability of fasting glucose
over a 1-year period of time, the calculated 24-hour integrated glucose concentration
was compared with their %tGHb. In 15 normal young medical students, the glucose area
response was determined from 46 venous blood samples obtained during a 24-hour period
and compared with their %tGHb. In 18 people with type 2 diabetes, interstitial glucose
concentrations were monitored using the Continuous Glucose Monitoring System (Medtronic
MiniMed, Inc., Sylmar, Calif) for 3 days at 20-day intervals over 100 days. %tGHb
was performed at 20-day intervals simultaneously. In 29 people with untreated type
2 diabetes, glucose area response was determined from 46 venous blood samples obtained
during a 24-hour period and compared with their %tGHb after being on a standardized
diet provided to the subjects for at least 5 weeks. The %tGHb and 24-hour profiles
were stable. Results: There was an excellent correlation between the mean 24-hour
glucose concentration and the %tGHb among subjects with diabetes. The correlation
was poor among subjects without diabetes. The relationship was curvilinear when plotted
as a single group. Alternatively when data from subjects with or without diabetes
were plotted separately, the slopes were identical but the y-intercepts were different.
Conclusion: The relationship between the mean glucose concentration integrated over
an extended period of time and the %tGHb is not linear. The reason for this nonlinearity
remains to be determined. This non-linearity needs to be considered in the clinical
interpretation of %tGHb (and probably HbA1c) in reference to glucose values.
Abbreviations:
%HbA1c (percent hemoglobin A1c), %tGHb (percent total glycohemoglobin), RBCs (red blood cells), HPLC (high-performance liquid chromatography)To read this article in full you will need to make a payment
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Article info
Publication history
Accepted:
May 25,
2005
Received in revised form:
May 24,
2005
Received:
February 24,
2005
Identification
Copyright
© 2006 Mosby, Inc. Published by Elsevier Inc. All rights reserved.
