A1cnow

I have a strange set of circumstances. I have a 17% difference between my lab HbA1c (38) and the average of 31.5 (over 8 readings 30 - 32) via the A1cNOW+. When I took 2 tests on the A1cNow+ 3 non diabetics tested on the same unit on 1 occasion and another non-diabetic on another occasion - all got higher readings than m. I know meter readings do not correlate directly to A1c 's but something weird is up. The 90 day averages across 6 different meters have been 4.3 / 4.4 mmol - these include fbg and post meal and random (one of the meters tracked perfectly with a calibrated diabetes professional unit (4.4 on that occasion with the same blood droplet). The only other logical explanation why I could have fbg's in the low 4's and post prandial numbers circa 5.5 or less (often 4.9 by early evening) was that I was somehow spiking during my sleep, so I have used a Freestyle Libre, as can be seen within the attached over a year and a quarter, my numbers have reduced by around 16%.

I have seen my doctor, who referred me to an Endo. The Endo cancelled my appointment saying he couldn't help?! Went back to my doctors who agreed the variance was not normal. I asked for the name of the testing equipment, and said I would pay for an alternative at the next text to compare....awaiting their response.

I know I am much better controlled than when I had a 35 A1c, I eat better, am lighter etc. An A1c of 38 equates to average glucose readings on 6.3 I believe, I am mainly in the 4's throughout the day, and unless 8 devices are wrong.

Point of care testing is generally not as accurate as tests sent off to the laboratory. Even laboratory results should be taken as an indication of the range in which the true result lies rather than a precise point. This is explained in this booklet about measurement uncertainty, aimed at GPs:- https://www.rcpa.edu.au/getattachme...284-19b5d1096ad3/Measurement-Uncertainty.aspx

The booklet explains that, in a test for HbA1c which has a coefficient of variation of 3%, a test result of 48 mmol/mol would indicate that the 'true' value lies somewhere between 43 and 52, while a test result of 42 mmol/mol would indicate that the 'true' value lies between 38 and 46. In an evaluation of home testing for HbA1c, the coefficient of variation for a1cnow has been reported as being less than this (4.57%):- https://www.researchgate.net/public...-the-Counter_Glycated_Hemoglobin_A1C_Test_Kit

The booklet about measurement uncertainty goes on to give this example case study/question:-
In addition to the limits described above, there are factors which can alter the value of the HbA1c, some of which are described here:- https://patient.info/doctor/glycated-haemoglobin-hba1c

Dark Horse said:

​

In addition to the limits described above, there are factors which can alter the value of the HbA1c, some of which are described here:- https://patient.info/doctor/glycated-haemoglobin-hba1c

Click to expand...

Three interesting sites, and food for thought. Think I will wait a few months and see my GP for his take on the differences.

Dark Horse said:

Point of care testing is generally not as accurate as tests sent off to the laboratory. Even laboratory results should be taken as an indication of the range in which the true result lies rather than a precise point. This is explained in this booklet about measurement uncertainty, aimed at GPs:- https://www.rcpa.edu.au/getattachme...284-19b5d1096ad3/Measurement-Uncertainty.aspx

The booklet explains that, in a test for HbA1c which has a coefficient of variation of 3%, a test result of 48 mmol/mol would indicate that the 'true' value lies somewhere between 43 and 52, while a test result of 42 mmol/mol would indicate that the 'true' value lies between 38 and 46. In an evaluation of home testing for HbA1c, the coefficient of variation for a1cnow has been reported as being less than this (4.57%):- https://www.researchgate.net/public...-the-Counter_Glycated_Hemoglobin_A1C_Test_Kit

The booklet about measurement uncertainty goes on to give this example case study/question:-

Mrs A is 48 and had diabetes diagnosed four years previously and is on oral hypoglycaemic treatment. Her GP monitors control with three-monthly HbA1c measurements. Three previous readings are 6.6, 7and 7.4 % (49, 53 and 57mmol/mol). Question: The GP is concerned that her control is deteriorating. Is that correct? Answer: Not necessarily. All these results are within the same MU, and cannot be distinguished from each other.
​

In addition to the limits described above, there are factors which can alter the value of the HbA1c, some of which are described here:- https://patient.info/doctor/glycated-haemoglobin-hba1c

Click to expand...

Great post, much better explained than me!

Remember it needs two A1c results at least 2 weeks apart to diagnose diabetes.

I use a1cnow tests so just adding my bit of info.

I bought my latest box of 10 for £120 delivered from Amazon. Miller medical supplies. Previous to this it was from Medicare uk £117 delivered.

Re results, here goes:

33 on 26th Oct to get an idea of where I was on the scale. I knew my 6 monthly blood check was due. It tallied more or less with Mysugr prediction of 34.0. So i was happy. But I have had lots of peanuts since, trying to keep my weight up and actually gain a couple of lbs. With cheese and olives etc. Usually during the evening when I realised I hadn't eaten enough during the day. But @shelley262 quite rightly pointed out they aren't nuts but pulses! I was reading carb content. Anyway you live and learn. Thank goodness for this forum and all the very helpful members.

I did another test last Friday before I went for my DN appointment, it was 39! I was shocked so did another straight away, 41!!! As it happens my appointment was cancelled. DN had broken her wrist so i had to go to the walk in centre Saturday. So i used another home test. Just one day later and it was 35!!! I phoned surgery for my results today. 39! So in my opinion the a1c now gives you a rough idea of where you are. I'm going to continue using it once a month for just that reason. Hope this is useful.