Glucose Meter Comparison: Are They Really All the Same? Also: Do NOT Eat Korean Buckwheat Noodles!

diabetes glucose meter blood sugar monitor comparison glucometer comparison b|braun caresens accu-check

I have four different glucose meters, a.k.a. glucose monitors, blood sugar monitors, and glucometers. The point of this glucose meter comparison is to answer the (age-old?) question of whether they’re really all the same!

Summary: I tested four different glucose meters and found that they all gave similar blood sugar readings, but there were a couple of outliers. Generally speaking, though, they all did their job within a range that I think is enough to conclude that most glucose meters are similar to the point that it’s not worth agonizing over which one to get.

In the few times that I’ve tested with one glucose meter and then retested with another, the results really have been very similar. That led me to conclude back in April, on my 1-year ‘beetus anniversary, that it really doesn’t matter what brand you get.

diabetes glucose meter blood sugar monitor comparison glucometer comparison b|braun caresens accu-check

But I have to admit … at that point, I really hadn’t done the “science” that would legitimize such a conclusion. Therefore, I now submit this post as my entry into whatever shitty diabetes science fair might exist somewhere in the world.

I won’t torture you (or myself) by attempting to go full-academia in the reporting of this “study,” but some research basics are worth adhering to, however loosely.

We’ll start off with basic info about the equipment and methods, and then I shall attempt a very half-assed analysis of the data. After that, we’ll wrap things up with an attempt at a scientifically informed conclusion.

Glucose Meters Tested

Four different glucose meters were used for this study. Or is this an experiment? Meh. Here they are:

  • B|Braun Omnitest 3
  • CareSens N
  • Accu-Chek Performa
  • Accu-Chek Instant

All test strips were well within their expiration dates, with the earliest expiration date being March 2021.

diabetes glucose meter blood sugar monitor comparison glucometer comparison b|braun caresens accu-check

Testing Method and Procedure

I decided that I wanted to get an idea of each glucose meter’s consistency with its own readings as well as how each compares against the overall results.

I also wanted to get a sense of how each glucose meter reads blood sugar increases as opposed to just a one-off reading.

So in addition to doing a fasting blood sugar test, I also did a before-and-after blood sugar comparison of how much my glucose climbed after eating some buckwheat noodles.

diabetes glucose meter blood sugar monitor comparison glucometer comparison b|braun caresens accu-check

I did three tests of my glucose meters with three “sets” per test. I am defining a “set” as a group of four blood sugar readings: one from each of my four glucose meters.

  • Test #1: Right after work when I got home
  • Test #2: Right before eating the buckwheat noodles
  • Test #3: One hour after eating the buckwheat noodles

Since each test consisted of three sets, that means each test was made up of 12 different blood sugar readings:

  • 3 readings on the B|Braun Omnitest 3
  • 3 readings on the CareSens N
  • 3 readings on the Accu-Chek Performa
  • 3 readings on the Accu-Chek Instant

If this sounds confusing, it’ll make a lot more sense down below when you see photos of the actual blood sugar readings.

As for applying blood to the test strips, I only punctured my finger once per test, and I used blood from that very same hole in my finger for all 12 readings.

I also used three different fingers on the same hand, if that matters … and I’m not sure it does. I used my left hand ring finger for Test #1, my left middle finger for #2, and my left index finger for #3.

So I stuck my fingers good, squeezed out a big glob of blood, and touched all four glucose meter test strips to it. Then I reloaded and did it again, squeezing out more blood if needed. Same for the third set.

Test #1 Results: Fasting Blood Sugar

This was at 6:20 pm, right after I got home from work, and I hadn’t eaten anything in several hours.

diabetes glucose meter blood sugar monitor comparison glucometer comparison b|braun caresens accu-check

The photos above aren’t exactly in chronological order (whoopsie), but I’m not sure if that even matters. All blood sugar readings were taken in quick succession, and here they are:

Blood Sugar Test #1 Set 1 (A1) Set 2 (A2) Set 3 (A3)
B|Braun Omnitest 3 102 105 108
CareSens N 107 111 113
Accu-Chek Performa 126 126 130
Accu-Chek Instant 122 117 116
All blood sugar readings are mg/dL

From this first test, it looks like each glucose meter is pretty consistent with itself. In other words, one test from Brand X is very similar to other tests from that same brand.

The big takeaway from this first test, though, is that the Accu-Check Performa seems to be testing significantly higher than the other three glucose meters.

I’ve seen this before, like when the lady at Dr. Dump’s office would check my glucose (her glucose meter was a brand called Barozen) and then I’d check at home 5 minutes later on the B|Braun, only to get a reading that was 20 points off.

So I guess you could argue that the Accu-Check Performa is high but still within what could be called a “reasonable” margin of error.

Alright, let’s move on to the food part of this fascinating journey.

The Buckwheat Noodles

diabetes blood sugar test korean food naeng myeon buckwheat noodles 냉면
Non-diabetic me used to eat naeng-myeon at least once or twice a week during the summer! It is now September, and this was my first time eating this this year.

This isn’t just a glucose meter comparison. It’s also a before-and-after blood sugar test of a specific food, just like I normally do on Diabetes Is Bad!

I tested some buckwheat noodles in May 2019 when I ate some bibim-kuksu (비빔국수), and the results sucked. I didn’t weigh the noodles at the time, but I ate them all and went from 108 → 197.

So I already knew that buckwheat noodles, despite whatever Google says, are not great for diabetics.

I’m told that buckwheat noodles often contain very little actual buckwheat and the rest is just regular flour, and I believe it.

diabetes blood sugar test korean food naeng myeon buckwheat noodles 냉면
These photos aren’t scaled to each other exactly, but this side-by-side is not that far off from reality.

For this test, I was eating some naeng-myeon (냉면), a Korean dish that is basically a cold noodle soup. It’s great in the summer, and I loooooove it.

Naeng-myeon is buckwheat noodles swimming in ice water that includes cucumbers, shaved radish strips, red pepper paste (gochu-jang), sesame seeds, some kind of kimchi, half a hard-boiled egg, and however much white vinegar and spicy mustard you choose to add. I choose to add a lot cuz I love that hot mustard.

Since last year’s bibim-kuksu test didn’t go so great, I tried to be smart about the buckwheat noodles this time around.

diabetes blood sugar test korean food naeng myeon buckwheat noodles 냉면
520g of noodles is a lotta damn noodles

I removed the noodles from the ice water and weighed them: 520g! That’s over a pound of noodles. So, in an attempt to be a very cautious diabetic, I grabbed a pair of scissors and cut the noodles in half.

I approximated half the liquid and all the rest, and I settled for 260g of noodles + the hard-boiled egg. Immediately upon finishing, I set a timer for one hour.

diabetes blood sugar test korean food naeng myeon buckwheat noodles 냉면

Test #2 Results: Before Eating the Buckwheat Noodles

diabetes glucose meter blood sugar monitor comparison glucometer comparison b|braun caresens accu-check

Since this was nearly two hours after Test #1, I guess you could say this was the “real” fasting blood sugar test. In between Test #1 and Test #2, I took Terry out for a walk, but mostly we just sat outside like two old men.

Here are the results of Test #2 in chart form:

Blood Sugar Test #2 Set 1 (B1) Set 2 (B2) Set 3 (B3)
B|Braun Omnitest 3 101 104 97
CareSens N 95 102 97
Accu-Chek Performa 113 127 116
Accu-Chek Instant 101 103 102
All blood sugar readings are mg/dL

This looks a lot like Test #1, but with slightly lower numbers because some time had passed.

The Accu-Chek Performa once again gave the highest readings of the four glucose meters. And oh look, the Accu-Chek Instant definitely wins the consistency battle on this one.

Test #3: After Eating the Buckwheat Noodles

diabetes glucose meter test blood sugar monitor comparison glucometer comparison b|braun caresens accu-check

First of all: Holy shit! I only hate HALF the noodles, and I go from the low 100s to 300+? WTFFFFFFF.

I waited my usual period of one hour before doing Test #3. And if I had eaten all 520g of the naeng-myeon, I’d probably be in a goddam coma right now. Consider that a lesson learned! Geezzz.

Now since we’re doing charts, here are the numbers:

Blood Sugar Test #2 Set 1 (C1) Set 2 (C2) Set 3 (C3)
B|Braun Omnitest 3 280 315 294
CareSens N 333 345 370
Accu-Chek Performa 316 366 325
Accu-Chek Instant 314 316 326
All blood sugar readings are mg/dL

Alright, sooooooo … this is a surprise! The Accu-Chek Performa consistently gave the highest blood sugar readings in both Test #1 and Test #2. But in Test #3, the CareSens N grabs that crown and runs off with it.

370? Really, CareSens? And the Accu-Chek Performa wasn’t far behind with a 366.

Data Analysis #1: Consistency

Just a quick reminder, this was my stated goal at the start of this deep dive into glucose meter hell:

I wanted to get an idea of each glucose meter’s consistency with its own readings as well as how each compares against the overall results.

To do this, let’s look at each of these things separately. First, we’ll try to understand each glucose meter’s consistency with its own readings.

Pardon me in advance if I screw up the math words and general methodology. I’m not a statistician. I can barely add and subtract.

B|Braun Omnitest 3
Test Results Range (High-Low)
Test #1 102 105 108 ±6
Test #2 101 104 97 ±7
Test #3 280 315 294 ±35
Average Range (Tests #1 & #2 only): ±6.5
Average Range (All Tests): ±16.0
All blood sugar readings are mg/dL
CareSens N
Test Results Range (High-Low)
Test #1 107 111 113 ±6
Test #2 95 102 97 ±7
Test #3 333 345 370 ±37
Average Range (Tests #1 & #2 only): ±6.5
Average Range (All Tests): ±16.7
All blood sugar readings are mg/dL
Accu-Chek Performa
Test Results Range (High-Low)
Test #1 126 126 130 ±4
Test #2 113 127 116 ±14
Test #3 316 366 325 ±50
Average Range (Tests #1 & #2 only): ±9.0
Average Range (All Tests): ±22.7
All blood sugar readings are mg/dL
Accu-Chek Instant
Test Results Range (High-Low)
Test #1 122 117 116 ±6
Test #2 101 103 102 ±2
Test #3 314 316 326 ±12
Average Range (Tests #1 & #2 only): ±4.0
Average Range (All Tests): ±6.7
All blood sugar readings are mg/dL

I’m not sure if three tests per glucose meter is enough data to definitively say whether the Accu-Chek Instant has truly kicked the asses of the other contenders here for consistency, but it sure looks that way.

In the fasting blood sugar department, which describes Test #1 and Test #2, all four units performed really well. The worst average range (where we look at the gap between the highest and lowest readings) was the Accu-Chek Performa’s ±9.0, and that’s really not that bad.

But where things really go down the shitter is in reading the post-meal blood sugar spike. The Accu-Chek Instant was the only one of the four that maintained a pretty reasonable range of ±12.

diabetes glucose meter blood sugar monitor comparison glucometer comparison b|braun caresens accu-check

The others? Accu-Chek Performa at ±50? C’mon man. And the ±35-37 numbers for B|Braun and CareSens are nothing to brag about either.

And even if you include the blood sugar spike readings, the Accu-Chek Instant’s overall average range is still a very reasonable ±6.7.

So the undisputed champion of the Consistency Battle is the Accu-Chek Instant.

Data Analysis #2: Overall Comparison of Readings

I have to admit that I’m not 100% sure of how to go about this, so let’s start by looking at each glucose meter’s average for each of the three tests.

Glucose Meter Average Readings by Test
Test # B|Braun Omnitest 3 CareSens N Accu-Chek Performa Accu-Chek Instant
Test #1 105.0 110.3 127.3 118.3
Test #2 100.6 98.0 118.6 102
Test #3 296.3 349.3 335.7 318.7
Test #1 Average: 115.3
Test #2 Average:: 104.8
Test #3 Average:: 325.0
All blood sugar readings are mg/dL

Ok, you know what? This is good enough for me! People with math brains would probably want to calculate standard deviation and graph a parabola or some shit, but that is way beyond (a) my brain’s capabilities, and (b) how much I care.

What this chart of averages tells me is that Tests #1-#2, the “fasting blood sugar” tests, are pretty reliable no matter what kind of glucose meter you’re using.

Sure, the Accu-Chek Performa might have overshot it a bit, but not by an outrageous amount.

Test #3 is where things kind of fall apart … again. There’s a pretty big difference between B|Braun’s 296 and CareSens N’s 349.

But still, all four glucose meters put you somewhere in the low-ish 300 range, and I suppose that’s really all you need to know.

Whether you’re at 296 or 349 or somewhere in between, you can now make a mental note of whatever you ate an hour ago and resolve to never eat it again.

But if we have to pick a winner, meaning the glucose meter that is most representative of the overall results of all these tests, I think I’d have to hand that award to the Accu-Chek Instant as well.

Conclusion

These tests have all proven that there is definitely going to be some variance in blood sugar numbers, even if you test yourself twice in a row with the exact same device.

But if we go back to the original question of this quasi-scientific “study,” can we conclude that all glucose meters are the same?

My answer to that would be “mostly yes.” All four of the glucose meters tested here have told us more or less what we want to know.

I think the Accu-Chek Instant did the best job according to my very shaky math, but the others didn’t do too bad either.

And I guess it’s also useful to know that if your blood sugar is high, it might even be a bit higher than your glucose meter is letting on! Yay. Wonderful.

So I stand by my assertion that it doesn’t really matter what kind of glucose meter you use as long as you actually use it.

Keep an eye on what you’re eating and do enough tests to understand how your diet is affecting your glucose levels. Your trusty glucose meter will at least put you in the ballpark so that you can make the right food decisions going forward.