I have predicates, and recently my HbA1c results have increased, despite my home monitoring with a finger prick meter showing no increase in sugar levels, after fasting, 2 hours after eating and random tests.
I since discovered that the HbA1c is not as accurate as one might think it is.
Follow this link for one of many reports on the problem of this test.
care.diabetesjournals.org/c...
Michaelx
HbA1c is a long term marker of how well your blood sugar levels have been controlled over the past few months. As such I am not sure how valid it is to try and compare it to single measures of a different metabolite.
It is possible for home test kits to be off kilter. A friends father managed to have a hypo a few months ago because of a fault in the prick meter he was using.
Yes I understand that, but please read the report. It clearly talks about the dangers of averaging populations rather than individuals. I seems to me that the report makes sense, because not everyone's blood cells are going to rejuvenate over the same time and at the same rate. The HbA1c assumes that everyone's blood cells rejuvenate over 3 months, and clearly they don't.
Michaelx
The article is actually about the dangers of using a statistical average to say whether an individual is okay - which is bad logic anyway but is the logic that unfortunately gets applied to a large number of clinical measures and is a long way from unique to diabetes.
The article does mention various forms of anaemia but also states that using HbA1c as an absolute unique measure can be problematic even when these anaemias aren't present - so it isn't about whether or not you have a condition that means your red blood cells live for a period different from 3-4 months.
The article is also comparing the position given with CGM kit and HbA1c so it may not be valid to compare to the results from a pin-prick test. It was also comparing the results obtained before the HbA1c test rather than after the test.
The message is that HbA1c ranges may need to be referenced to individual paramaters in a few cases - but that there, nevertheless, is a correlation (with the possible exception of cases of anaemia mentioned at the start of the article.
It isn't about how accurate the test is, as your title suggests. It is about the way it is being interpreted - and the bad logic of assuming that an average range applies to all individuals - 5% will fall outside the ranges anyway because that is the nature of statistics and the definitition of normal range. If you are concerned about a discord between HbA1c results and your actual glycemic control then I would suggest discussing with your GP using CGM for 14 days prior to a test as suggested by the article to determine if you are an outlier and if so, what the appropriate ranges are in your case.
The point is that the test is not as accurate as many people believe it to be.
The lifespan of red blood cells is an important factor. There are many other reasons for it's accuracy being challenged. In addition to the age of red blood cells , there is the persons age, ethnicity, disease, nutrition, medications and even alcohol.
Researches found in test that a heavy alcohol consumption affected the HbA1c distribution with lower proportions of HbA1c levels of ≥5.7% and ≥6.5%. This result suggests that excessive drinking shifts the HbA1c
In a study published recently in the journal Science Translational Medicine, the researchers show that not factoring the age of each patient's red blood cells into HbA1c estimations lead to identical readings for people with average blood sugar levels that can differ by as much as 0.8 mmol/l .
For example, one patient had his HbA1C measured initially at 65 mmol/mol (8.1%), leading to an estimated blood sugar level of 10.3 mmol/l. When the researchers factored in the person's red blood cell age of only 45 days, the estimate went up to 11.6 mmol/l.
Researchers in a different trial also found that the lifetime of hemoglobin cells of diabetics turned over in as few as 81 days, while they lived as long as 146 days in non-diabetics.
This proves that the assumption that everyone’s red blood cells live for three months is false, and that HbA1c can’t be relied upon as a blood sugar marker. In a person with normal blood sugar, hemoglobin will be around for a lot longer, which means it will accumulate more sugar. This will drive up the HbA1c test result – but it doesn’t mean that person had too much sugar in their blood. It just means their hemoglobin lived longer and thus accumulated more sugar. The result is that people with normal blood sugar often test with unexpectedly high HbA1c levels.
Your comment that the report is not about how accurate the test is, it's about interpretation , I believe is wrong. It is very much about the test not being as accurate as one might think, due to the many variables mentioned above, that can adversely affect the test and therefore affect the results. Is it not the case, the more accurate the test, the less interpretation is be needed.
I do accept that the HbA1c test accuracy based on statistical averages is not unique to the testing of diabetes. However, it was the HbA1c test that I was commenting on, not other tests that maybe flawed.
Finally, the whole point of the headline was to alert people about HbA1c testing, that is not as black and white as many would have us believe. I would hope that people read the report and investigate the HbA1c testing much further, and then come to their own more informed conclusion.
Michaelx
Sorry Michaelx but I disagree with you - the article isn't about the accuracy of the test, it is about the interpretation of the test and hence the conclusions that can be drawn from the test.
The accuracy of the test is about how much the output measurement from the test varies. The article is about how the output from the measurement is being interpreted (and the problems with applying average measures to specific individuals.
The section in relation to 'life-cycle' of red blood cells is, as I understood it a reference to previously published and accepted limitations of the test - conditions in which it is already known to be difficult to interpret. The article then goes on to explain the fact that these aren't the only conditions in which interpreting the results isn't straightforward.
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Diabetes HBA1C test
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