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Performing blood glucose tests in the afternoon rather
than the morning may mean up to half of all
cases of diabetes are missed, new research published in the
Journal of the American Medical Association (JAMA) suggests.
This is due to the fact that blood sugar levels vary throughout the day,
and have been shown in other studies to be generally higher in the morning.
Researchers from the National Institutes of Health studied about 12,900
adults undergoing blood sugar tests and found that:
- Using the current level of
diagnosis of 126 mg/dL, about half of all cases of diabetes
were missed
- The average fasting plasma glucose levels were
97.4 mg/dL in the morning group and 92.4 mg/dL in the afternoon group
- If afternoon blood glucose levels are used, the
level used for diagnosing diabetes should be reduced
to 114 mg/dL, the researchers determined
Current recommendations for diagnosing diabetes
are that patients have their blood sugar tested after an overnight fast
of at least 8 hours.
There are several possible reasons for the discrepancy
between morning and afternoon testing:
- Patients seen in the afternoon may have had a
shorter fast.
- There is a daily fluctuation in blood sugar levels
with lower levels in the afternoon.
Researchers conclude that patients who must be seen in the afternoon fast
for at least 4 hours before testing and that the test should probably be
repeated in a morning visit.
Journal of the American Medical Association,
December 27, 2000; 284: 3157-3159
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