The A1C Test for Diagnosis
An international expert committee has recommended a new way of diagnosing whether someone has diabetes. Currently, most people are diagnosed via fasting glucose tests or oral glucose tolerance tests. But these tests offer only a snapshot of glucose levels on a particular day, a number that can by swayed by exercise, illness, or even the temperature of the room in which the blood sample is housed. That’s why the panel is recommending a switch to the A1C test for diagnosing diabetes. The A1C test, which people with diabetes should have every three to six months, reports an estimated average blood glucose level during the preceding two to three months. This is thought to be more accurate than the other tests and doesn’t require fasting or a long doctor’s visit. According to the committee, made up of representatives of the American Diabetes Association, the International Diabetes Federation, and the European Association for the Study of Diabetes, an A1C of 6.5 percent or greater—a cutoff determined by the point at which the risk of diabetic retinopathy starts to rise dramatically—indicates diabetes. The ADA has not yet made an official statement on using A1C as a diagnostic tool.
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If the test is only given every 3-6 months how does it register an average without your regular readings. The test I believe is not as accurate as your committe suggets as it is done either fasting and sometimes non-fasting which also attributes to the reading. It reflects only the moment based on the time the blood is drawn which could also be affected from stress, hunger, etc.
A1c test
For this to make sense to you, it is important to know how an A1c test works. Normally a certain amount of glucose (sugar) in the bloodstream attaches to our red blood cells. The higher your blood glucose is, the more glucose attaches. The amount of sugar attached can be measured. The average lifespan of a red blood cell is 2-3 months, which is why this process gives you a 2-3 month average of your blood sugars. The test can be fasting or random because it is a long-term average, not a snapshot. A person's A1c gives you one type of information - an average. It does not tell you how high or how low the person's blood sugar has gone. A person with a lot of highs can have a normal A1c if he/she has also had a lot of lows. But this usually does not happen around diagnosis time when a person is not yet on medication, so it makes sense that we finally use it for diagnosis.
Inaccuracy of the A1C test
If you have large blood sugar swings from say 40 to 200 all of the time, the average may still be in the mid 90s and the A1C will not reflect the fluxuation in sugar since it only measures the average and not the dispersion. This is something to take into consideration.
ADA has made statement on using A1C for diagnosis
In their recent report (3), an International Expert Committee, after an extensive review of both established and emerging epidemiological evidence, recommended the use of the A1C test to diagnose diabetes, with a threshold of ≥6.5%, and ADA affirms this decision. The diagnostic A1C cut point of 6.5% is associated with an inflection point for retinopathy prevalence, as are the diagnostic thresholds for FPG and 2-h PG (3). The diagnostic test should be performed using a method that is certified by the National Glycohemoglobin Standardization Program (NGSP) and standardized or traceable to the Diabetes Control and Complications Trial reference assay. Point-of-care A1C assays are not sufficiently accurate at this time to use for diagnostic purposes.
http://care.diabetesjournals.org/content/33/Supplement_1/S62.full
new to A1C
was tested in the docs office yesterday because FBS drawn in December was 107 which is the highest I have ever had in my 71 years. I have been on a diet low glycemic low cholesterol and low fat and have gained weight the doc took my A1C and it was 5.8 I had a MI last June and have been exercising 3-4 hours a week should I be concerned that I may be a diabetic or be on my way to becoming why am I still gaining weight?
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