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Accu-Chek Meter vs SD Codefree - Wild Variations

Ronancastled

Well-Known Member
Messages
1,234
Type of diabetes
Type 2
Treatment type
Diet only
After I was diagnosed I purchased a SD Codefree online as it seemed to have the cheapest strips.
Like a muppet I managed to buy an American version mg/dl but dividing by 18 sorts that.
I began noticing that one batch of sticks could read 1+mmol/L higher than the previous but as they were only 10p a strip I'd order a new batch of 50 & chuck the bad ones.

About 2 months ago I purchased a backup Accu-chek that has a cassette which can take 50 tests.
Much more expensive, works out 70p per test but worth it if your worried about a bad reading.

So last week was my 3 month scheduled lab test so I brought both meters in the car.
Straight after leaving the surgery I took 2 readings on both meters from the same drop of blood.

Accu-chek: 4.7 & 4.8
SD Codefree: 119(6.6) & 106(5.9)

The lab result came back 2 days later at 4.7 so turns out the Accu-chek was deadly accurate.
My previous batch of Codefree strips were a lot closer to the Accu-chek readings but this new batch are way off again.
Perhaps we get what we pay for.

Anybody else notice the same ?
 
I bought my Codefree some 5 years ago. I get exactly this same problem no matter what the other meter is. I find I get readings that average over months to be always 1.2 mmol/l higher than my other meter, but the other meters track each other. However, like you I get rogue high readings from the SD that can be up to 10 mmol.l higher. Even on a retest. When this happens repeat tests are repeating the same huge difference. I find it is the readings just after eating that tend to trigger this difference, and suspect that there is some element of the food that the SD detects that the other meters do not.(probably Malitol) The test strips and electronics use different enzyme reactions, so this can happen due to different chemistries.

It is an extreme rare event for the SD to read lower or close to the other meter, and this indicates that my test site is contaminated. A quick wash and wipe sorts that out. So nowadays I use the SD as a sanity check on my other meter. I do average the two readings to reduce some of the errors in both meters, but I make my decisions regarding diet and meds on the other meter since I believe it when it tells me I am hypo, but the SD will probably be telling me it is safe for me to drive and operate machinery!!!!!! My body agrees with my other test meter and I am hypo aware.

This problem with SD meters seems to be systemic and has been reported frequently on this forum. The importer has investigated and reports that the manufacturer states that the meters are working to specification. My meter did not get replaced and I have learnt to live with it. I always assume the 1.2 mmol difference as a given now.
 

Hi @Ronancastled

Your 3 month scheduled lab test (HbA1c) returns your average blood glucose over the past 2 to 3 months in mmol/mol (or possibly a percentage). Your spot check returns your glucose reading in mmol/L. The units are not the same and cannot be compared like for like.

With many spot check results you can derive an average reading that may come out somewhere near the HbA1c value.

So ignoring the lab results (well done by the way - good result whether it's a percentage or mmol/mol) , all test meters sold in the UK/EU are required to conform to ISO standard 15197:2013 and must be accurate to within +/-15% for 95% of the readings (which allows for some rogue results) so it's entirely possible that your true glucose reading was around 5.7mmol/L and both meters are roughly within specification, with the Accu-Check reading lower than actual and the Codefree reading higher than actual.

Don't expect too much from home test meters.
 

My comparison check was based on FBG spot checks only.
My HbA1c's are as per my sig below, perhaps I should have made that clearer.


Point I was making is that the Accu-chek spot result was 100% accurate to the lab result, the lab blood having been drawn minutes before.
One of the SD Codefree readings was out by 40%, the closer one was out by 25%.
I find it depends on the batch of strips, the next pack might be spot on.
 
Ronancastled said:
Point I was making is that the Accu-chek spot result was 100% accurate to the lab result, the lab blood having been drawn minutes before.
Click to expand...

What result did you get from the laboratory ? What units was it in?
 
Disappointed, just tried codefree and it seems over 1.2 mmol/l higher than my normal readings, and it confirmed when i checked against Finetest Lite.
 
zamalik said:
Disappointed, just tried codefree and it seems over 1.2 mmol/l higher than my normal readings, and it confirmed when i checked against Finetest Lite.
Click to expand...
I have been getting exactly the same offset (1.2 mmol/l) for over 5 years now. I have compared mine against Abbot Xceed (2 different meters and strip packs), and my Abbot Neo that replaced the Xceed, and now my Caresense Dual. ALL of them had the same 1.2 mmol average offset difference, and always with the Code-free reading high. It is very rare when it has read lower, and on these occasions, it was always shown to be a misread on retry.

There are others doing this comparison that do not experience this problem so it seems to be the meter rather than the strips. My Codefree can be up to 4 mmol/l adrift and for it to retest this high again, so I suspect it is something in the chemical reaction to blood composition that gives these errors (hematocrit for instance?)

It is as if the Code-free is calibrated to whole blood rather than plasma calibration which is also 1.2 factor but the blurb sheet claims plasma.

The problem is that a 1.2 error is within the ISO requirements for the meter, so the supplier refuses to replace the meter as faulty. As oit is a fixed offset, I can live with it, and I set my spreadsheet to adjust accordingly.
 
However, its panic to see a reading of 6.8 as an 8.1. I almost declared my wife diabetic as well!
 
zamalik said:
However, its panic to see a reading of 6.8 as an 8.1. I almost declared my wife diabetic as well!
Click to expand...
It is even worse seeing a 5.1 while having the symptoms of a hypo, and needing to drive somewhere, By DVLA rules, the 5.1 allows me to get behind the wheel, but a 3.9 is hypoland. I have been there.

Personally, I do not let an 8.1 freak me out I have seen 32+ on my meter (It shouts KETONES at me, or HI,) and that is panic stations. But I have for 5 years now (at least) done a double meter sample with 2 different meters in parallel on the same drop just to make sure that I get a valid reading. So long as the Code free is higher than the other, and is within a couple of mmol. then I can accept it. But more than that is a bum steer and needs a retest. Expensive, but then I have the luxury that my Caresense strips are on scrip so I only fund the Codefree.

as regarding your wife, the rule is that one swallow does not a summer make, and there must to be two different tests to confirm. Usually one of those tests is an HbA1c. I presume she passes the retest.
 
zamalik said:
However, its panic to see a reading of 6.8 as an 8.1. I almost declared my wife diabetic as well!
Click to expand...
Funny you say that about your wife.
My last batch of codefree had been giving me 8+ for 4 hours post a low carb breakfast.
My non-diabetic wife who had just returned from basketball with the kids checked hers, & she had not had breakfast & measured 7.5.
That was the last time I used my Codefree.
 
Yeah, the take away from this is that we check our wives BG with Codefree so they can start low-carb with us too

My bro is very happy with Contour Next, though strips are quite expensive but he says its spot on.
 
 
I was diagnosed 9 weeks ago with a 27 first reading and terrible stomach ulcers.
I was given an Accu-check meter and with rigid changes to my diet and exercise programme thought I'd be close to remission, having halved the Metformin after two months to 500 twice a day.

Then I bought the CodeFree today and got this

There is great relief I'm not the only one. It knocked the wind out of my sails
 

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