A Tale of Two Glucometers


In addition to struggling with my weight, I have also been struggling with Type 2 diabetes the last couple years. I realize it’s nothing compared to what I’ve seen Type 1’s have to go through in terms of calculating how much insulin to take and when, but it’s frustrating when I find out I’m not doing quite as well as I thought I was.

When I first got diagnosed with Type 2 Diabetes two years ago, my A1C was 7.9. It had went down close to 6, but it’s now back to a 7.1 based on a recent blood test, which I will be discussing with my doctor as I go in for an annual physical.

Among the many other stats you get on a blood test is your current blood glucose level. Since I had to go in fasting, I checked before I went in. My meter gave me a 104 mg/dL. The blood test said 143 mg/dL, which is a huge swing! Another data point: my 3 month average on my glucometer was 126 mg/dL. The “estimated” average from my A1C number, which is supposed to reflect a 2-3 month average? 157 mg/dL.

All of that suggests my meter might be at fault. Given that I was having some technical issues with the iHealth meter I acquired a couple years ago, namely that it would lose track of which vial of strips I was using and, very recently, completely lost sync with my phone, I decided it was time to try a different meter. And, re-reading that old post, it seems I should have expected inaccurate readings might crop up again.

Rather than get another “smart” meter, I opted for something a bit lower tech based on a recommendation from Larry, a fellow diabetic: The Contour Next by Ascensia (formerly Bayer). It lacks Bluetooth, but I can plug a Micro USB cable to pull the data off of it, if I so choose.

The other redeeming quality of this meter: the strips are even cheaper than the iHealth meter, which is why I chose that meter in the first place. I actually bought 200 test strips and the Contour Next meter for about the same price I pay for 200 test strips from iHealth. And the Contour Next strips are much more widely available. I should check and see what they cost if I go through my insurance.

Since I still had a couple iHealth strips left, I figured I’d do a side-by-side comparison of the two meters from the same drop of blood. From Thursday night:

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And from Friday morning:

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How can two meters get such wildly different results? It’s hard to say, but it turns out, such inaccuracies are actually within the US FDA Guidelines for Self-Monitoring Blood Glucose (SMBG) Test Systems:

Blood glucose test results are used by people with diabetes to make critical decisions about their treatment; therefore, it is important that the results are accurate so that nutritional and drug dosing errors are better avoided. Your studies should demonstrate that your SMBG is sufficient for this purpose by showing that 95% of all SMBG results in this study are within +/- 15% of the comparator results across the entire claimed measuring range of the device and that 99% of all SMBG results are within +/- 20% of the comparator results across the entire claimed measuring range of the device

I suppose if my results were really high, a +/- of 20% wouldn’t be that big of a deal. On the lower end of the scale, where I am, that +/- 20% can make the difference between being normal and not normal, either mildly high or possibly hypoglycemic (low blood sugar, potentially very bad).

Regardless, I think I will stick with the new meter. Ascensia, which was a business unit of Bayer before it was sold to Panasonic Healthcare, has probably been making glucometers a bit longer than the iHealth guys have been in existence.

Edited to add second test result on 6 Jan 2017


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