Remember that the information presented here is not intended to replace the care of your own doctor. Before making any changes in the management of your own illness, you should consult your physician or other qualified medical professionals.
Question
The screening for diabetes is simple, quick, and not expensive, but it is not a diagnosis. I assume
that this screening is on the basis of a random plasma glucose test (just a regular fingerstick) — am I right? How valuable do you think screenings like this are? I'm sure that the other accepted diagnostic tests (e.g., a plasma glucose value of 126 mg/dl [7 mm/l] or more after an 8-hour fast or an
oral glucose tolerance test)
are impractical for mass screening, but I don't understand why the A1c is not an acceptable diagnostic tool. Is it acceptable if the level is high enough?
Answer
Traditionally, diabetes is diagnosed by elevated blood sugar values. Symptoms are optional,
because sometimes people have symptoms mimicking diabetes, but in fact the symptoms are later found to be due to other causes. Urine sugars would be misleading since they might be falsely positive in the
rare syndrome of
renal glycosuria
and falsely negative if
someone has a high
renal threshold
or mildly elevated blood sugars.
Why not use
HbA1c?
Not because the ADA makes the pronouncement that
The use of the hemoglobin A1c (A1C) for the diagnosis of diabetes is not recommended at this time.
(See DIAGNOSTIC CRITERIA FOR DIABETES MELLITUS,
and
notice they don't give a reference for their statement!)
I think it's simply since no one has done the clinical trials needed to ascertain the utility of the A1c in diagnosing diabetes.
Additionally,
older A1c methods could be confounded by abnormal hemoglobins, which would give elevated results in A1c assays even in people without diabetes.
I usually ordered both blood glucose and A1c if a patient presented with symptoms of diabetes. If both are elevated, it helps nail the diagnosis, and
gives a baseline A1c for later comparison.
wwq
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