Noumenon

I have got myself two meters, an accu-chek Performa, and it's smaller Nano version. We had a series of hot days in a row here (exceeding 35 Celcius) so I kept my strips and meters in the top drawer of the fridges door.

Yesterday, I did a fasting glucose test and got 5.2 mmol/L on one, and 5.8 mmol/L on the other. A variation of 0.6 mmol/L between two brand new meters.

Today when I did a fasting test, the readings were closer together 5.9 & 5.7.

In both days measurements were taken from the same lancet prick, and within a few seconds apart.

I still have the boxes that both meters came in, and despite each having substantial literature in multiple languages, none of the documentation actually has specifications and operating conditions.

I had to go online to find those and found the pertinent information to be "System Operating Conditions: 6°C to 44°C", which suggests that the fridge internal temps are probably not the best to operate it at, but I used them outside the fridge. Not inside it So that shouldn't have made that much of a difference.

Where I do suspect issues is that each meter probably took a different amount of time to warm up to ambient temperature [as one meter is about twice the size of the other], and I didn't give either meter sufficient time to warm up, the first day before taking measurements.

I do know that glucose measurement does take into account ambient temperature, but it probably assumes the meter is also at ambient temperature.

Any ideas, experiences?

And do you think I should get both meters calibrated? I mean first day readings were 0.6 mmol/L apart, but following measurements were closer together. Then again they could both be off.

DocTerry

I never heard of a meter that could be calibrated! However, I do know that meters are not precisely accurate...they don't need to be, and the cost of producing a more accurate meter/strip combination would be prohibitive.

However, something that my doctor told me years ago: "If you were like a bottle of Pepto Bismal I could pick you up and shake you around until your blood was thoroughly mixed--however, until that time comes you just have to accept that the blood in your finger is changing constantly and even a reading in EXACTLY the same spot with the fictional precise meter could give different readings."

In any case, we don't rely on a single reading so if you get readings that are constantly between 5.5 and 6.5 you can be satisfied that your sugar is under control.

Shanny

FDA regulations allow a variance of ±20% which gives a lot of wiggle room.

Next time you have labs done, take your meters & test at the same time. Comparing your meter readings with the lab results may help you decide which one you like better. For my own use, I have one meter & as long as it's consistent with itself, I don't worry too much. My next labs are coming up in March, and I'll be checking mine then.

Noumenon

Hi DocTerry, Shania,

All measuring instruments can and should be calibrated. Calibration at it's simplest means validation of measurement techniques and methods, and usually involves comparing those techniques and methods with some standard. In the case of the Accu-chek Performa glucose meters, one can purchase Control Solutions, which should make the meter read specific Hypo and Hyper readings.

I did find a short document about the Accu-chek meters meeting ISO 15197 standards [The FDA is a US Authority, in Australia we have the TGA, but usually instruments have to meet some international ISO standard]. And the article suggests that for readings above 4.2 mmol/L (about 75 mg/dL), a variance of up to 20% is acceptable, and further goes on to state that their meters are even better.

But it says nothing about refrigerating meters, then bringing them out to take measurements in ambient temperatures, nor how long to leave the meters out so they can they reach ambient temperatures, stabilise, then we should take measurements. That's probably because the standard doesn't require such rigour. Even though the literature that came with the meter does state that strips should be kept below 33 Celcius. Whilst the meters operating conditions are between 6 Celcius and 44 Celcius.

In the absence of such literature I guess I will have to use common sense, allow some time for the meters to reach ambient temps, then take measurements, and still allow for a variation of up to 20%. 20% around 5.5 mmol/L can be as low as 4.4 mmol/ and 6.6 mmol/L. Better yet, I should perhaps refrigerate the strips, and keep the meters out at ambient temps.

Most instruments however are not linear. Glucose meter, or otherwise, they're usually designed to be most reliable in the middle range, and then their accuracy is progressively worse off towards either extreme.

Most users don't care for precision, accuracy, and so most manufacturers will either spell this out in the back of the manuals under specifications, or completely leave it out so as not to confuse the end user. But I personally like to know the limitations of the tools and instruments I use, as that gives me a better understanding of how much reliance / emphasis I should put on their readings.

Thank you both for your insight and feedback.

__________________
Diagnosed Denial Type 2 on Jan 2010, personally I think I have Glucose Intolerance and Insulin Resistance, and am not yet Diabetic.
OGTT: FPG 6.1 mmol/L, 1 Hr after 75g Glucose Load 14.4 mmol/L, 2 hr's after 75 g Glucose Load, 14.6 mmol/L
HBA1C: 6.2 %
Random: 10.1 mmol/L
Meters: Accu-chek Performa, and Accu-chek Performa Nano.

Anthill

I have a performa too as this meter has better tempreture handling abilties than most meters and the strips are good too as they can be tested before each test and calibration is also done to operate in great temp ranges too.

With the insulins there has been better ranges for use although keep them out of the sun as now our temps are quite hot indeed and keep cool. Don't leave insulins in the car!!!! I guess that's quite oblivious.
I live in Melbourne as today the sun had a day off but that will not last.

__________________

Type 1 Diabetic for 37 Years.
Insulins Novorapid and Levemir.
So I am well armed to enjoy food of any kind!!!
Peter...

Shanny

(enjoy it while it lasts, Peter!!! )

Noumenon

Today the temps rose to 32C (89.6 F), and right smack in the middle of the that I took my 3 hr walk. Yes, hat, sunnies, and slopped on 30+spf lotion. In the beginning of it I hopped over to a recreation oval and did some stretches, then did 2 laps around the soccer grounds (jogging), then I continued on my walk. My walk is 11.2 km's (6.96 miles) thru residential streets, along main roads and highways and a good third of it along the beach.

I'm getting fasting glucose as low as 4.1 mmol/L

__________________
Diagnosed Denial Type 2 on Jan 2010, personally I think I have Glucose Intolerance and Insulin Resistance, and am not yet Diabetic.
OGTT: FPG 6.1 mmol/L, 1 Hr after 75g Glucose Load 14.4 mmol/L, 2 hr's after 75 g Glucose Load, 14.6 mmol/L
HBA1C: 6.2 %
Random: 10.1 mmol/L
Meters: Accu-chek Performa, and Accu-chek Performa Nano.

Anthill

Thanks Shanny.

Quote:

Originally Posted by Noumenon I'm getting fasting glucose as low as 4.1 mmol/L

As long that the BG don't fall too low, You're OK. But a good effort. Good stuff.

__________________

Type 1 Diabetic for 37 Years.
Insulins Novorapid and Levemir.
So I am well armed to enjoy food of any kind!!!
Peter...

Noumenon

I should be so lucky. I mean, I'd like to have it hug the low 3's all the time, but I should be happy with 4's for fasting and 5's, sometimes 6's for post-prandial.

Sub 3's are hypo right?

__________________
Diagnosed Denial Type 2 on Jan 2010, personally I think I have Glucose Intolerance and Insulin Resistance, and am not yet Diabetic.
OGTT: FPG 6.1 mmol/L, 1 Hr after 75g Glucose Load 14.4 mmol/L, 2 hr's after 75 g Glucose Load, 14.6 mmol/L
HBA1C: 6.2 %
Random: 10.1 mmol/L
Meters: Accu-chek Performa, and Accu-chek Performa Nano.