When you purchase a blood sugar monitor, you want to feel like you’ve purchased the best, a monitor that is most accurate and gives you a meaningful blood sugar reading.
But it’s not uncommon that we get questions about why two different monitors give out two different readings.
For instance, a participant in our 21 Day Lower Blood Sugar Challenge purchased a new meter for daily readings during the challenge. The original glucometer is ONE TOUCH VERIO, the second is CVS Health Advanced Glucose Meter – both gave a completely different reading from the exact same blood sample. How can this be so??
You will be surprised to learn that this is normal and considered acceptable, though of course confusing and definitely not ideal.
So let’s explore this in a little more detail, including:
- what’s considered an acceptable variance
- how the best blood sugar monitors are tested for standards
- most accurate blood sugar monitors according to science
What’s considered an acceptable variance for monitors?
The FDA standards allow a 15% variance in home monitors.
This certainly is confusing and definitely not ideal but it is a fact. This variance is considered acceptable.
Even for hospital monitors a variance of 12-15% is considered acceptable.
How the best blood sugar monitors are tested for standards?
There are two widely accepted standards:
- The FDA – over-the-counter monitors must meet data pair tests to be within 15% variance.
- The International Organization for Standardization (ISO 15197:2013) – 15% variance for levels above 100 mg/dL (5.6 mmol/L), or a maximum of 15 mg/dL (0.8 mmol/L) for levels under 100 mg/dL (5.6 mmol/L).
So in general, these standards set the accuracy limits of a 15% variance for blood sugar monitors.
Depending where in the world the monitors are marketed, they are required to meet these standards.
But these monitors are not frequently tested by an independent body. And according to science, companies are deceiving customers because many of these blood sugar monitors don’t measure up to these standards!
The most accurate blood sugar monitors, according to science
Researchers investigated 18 popular blood sugar monitors cleared by the FDA, representing approximately 90% of commercially available monitors. They set the upper limit to 15% variance on readings.
Out of the 18 blood sugar monitors tested, only 6 monitors passed both the FDA and ISO accuracy tests!
The best, most accurate blood sugar monitors are:
- Roche Accu-Chek Aviva Plus
- ARKRAY Walmart ReliOn Confirm (Micro)
- AgaMatrix CVS Advanced
- Abbott Diabetes Care FreeStyle Lite
- Roche Accu-Chek SmartView
- Bayer Contour Next
This is quite surprising being that people with type 2 diabetes and prediabetes depend on their blood glucose monitors for day-to-day management.
It is even more surprising that compliance is largely left to manufacturers and is allowed to pass the FDA and ISO tests without an independent body regularly evaluating monitors for their accuracy. Crazy stuff!
You deserve to be informed about this! Especially since blood sugar monitoring is so critical to self-care in diabetes. The more accurate a meter, the better a person can manage their health.
Thankfully, the Diabetes Technology Society now has a blood sugar monitor surveillance team. They produced the research on the accuracy of these monitors presented above.
We will be keeping an eye on their future research so we can keep you updated.
I have 3 tests kits. Each one gives a different reading i.e. 7.2, 8.00 8.8 which one I’d correct 😡
Hi Christy, glucose monitors can have up to a 15% variance, which means the readings you’re seeing could all be within that expected range. To get more consistent results, it’s best to stick to one device only and always use it for your testing. This helps reduce variability and gives you a more accurate picture of your blood glucose trends over time.
15% +/- for testing is to me completely useless since I am just on the side of diabetes from pre. Are CGM systems more accurate?
I know it can feel like 15% +/- is problematic, but even as a pre-diabetic the information is still very valuable. For starters, remember that a finger stick reading is only one point in time – there is no guarantee that in 5 minutes your sugar won’t naturally be a 15% higher reading. (In real life, this would show a 99mg/dl reading, and then rising by 15% to 113mg/dl a few minutes later. This is not significant!) Blood sugar readings fluctuate naturally and do so for everyone diabetes and non-diabetes alike. Instead, I encourage clients to focus on trends. If your readings are fairly consistent and within what you and your doctor deem an acceptable range, then you are probably doing all the right things. However if your readings are more sporadic, where one morning your sugar is 99mg/dl and then the next it’s 172mg/dl, then you would likely want to do some diet/lifestyle trial and errors to become more consistent. CGMs are also susceptible to some inaccuracies (I don’t know if there is a published percent, per se) but continuous glucose meters can be a great tool to really observe those trends and make informed decisions with the additional information. Let us know if you have anymore questions about this topic!
I can test myself 3 times in a row using different test strips and lancets and will get 3 different results with each strip just seconds apart. Crazy.
How much of a difference are we talking? If the variations are less than 10mg/dL apart, I wouldn’t give it much thought as that’s pretty insignificant. However, if you are seeing large fluctuations of 25-30mg/dL or more, then you should investigate further. Some meters come with a calibration solution to help check the accuracy. You could consider changing the batteries or, if the meter, is older it may be time to upgrade.
I am a bit overwhelmed with the carb counting. This is certainly a challenge.
So todays number are: Fbs and Post Prandial : 114.
Today I ran into a question, goes like this.
I don’t think I fully understand the post prandial. I took the fasting blood sample and counted ahead by 2 hours. So in preparing breakfast I ended up eating while I was cooking.
So I took a guess at what the number might be. I was left with during the 2 hour post prandial are we suppose to go for a walk, and be active or can we sit back and read a book and hopefully relax. So doing the finger prick is what I came up in an extended time lapse – meaning not absolutely or accurately sure that that number is correct.
ps I have a roche and I like it a lot.
It is cold here in the mountains, rain and snow likely tomorrow. Choices at the market are slim.
Also a while a go you showed us a food list for vegetarians Would you show us again or put a link to that.
Thank you very much for all you do.
Whoops.
I forgot to enter the fasting bs which is 90 today.
One more thing: besan flour/chickpea flour is that a carb we we can or should be using. Before the challenge I was making chickpea flour crepes. So simple. and you can turn it into a wrap or spread with homemade Greek yogurt.
That’s all
Raani
Chickpea flour is considered a moderate carb option and is best consumed in small portions. Depending on brand, 1/4 cup can range from 13-18g of carbs. You certainly don’t want to have too much of it.
Hi Raani, some people don’t count, they just stick to the guidelines. Everyone is different so if counting is not for you, that’s fine too. If your levels are 114 that is looking good. You want your postprandial to be below 140 (ideally) 2 hours after a meal. Look…don’t get too caught up on the details because of course there will be all sorts of situations surrounding when you take it (not exactly 2 hours) or what you might do in between. Taking your levels regularly just gives you INFORMATION. That information can help you track patterns or identify when you might be high and how food or other factors may be affecting you. If you have the downloads for blood sugar charts and the paired monitoring, they give some tips there too. Vegetarian food list is here.
Have you heard of plant based Berberine to take instead of metformin? I’ve heard rumors that metformin can cause kidney problems…???
Hello Christina, check out our article on Berberine for more information!
Fbs was 98….
Fabulous! Thanks for checking in Ray.
I am on Medicare and if you want to get supplies covered, you have to use the meter they approve. For several years it was the Contour Next which I see was one of the more accurate. Now this coming year, they switched to OneTouch. Sorry they switched because it is not on the top 6.
Hi Pat! Thanks for letting us know about the change in approved meters for Medicare. I was not aware of that.
153
Thanks for checking in Sherry!
Hi Jedha,
I see your article on glucometers :) and have another question: Per your article
“Researchers investigated…They set the upper limit to 15% variance on readings”. This may be good to know but my math skills are shot to hell! My FBS this morning were 142 (Verio) and 182 (CVS). Is this within the 15% variance? It looks like 40 points to me…
PS: Same scenario as I originally mentioned with an added step; CVS advised me to dump the first drop of blood, and use the 2nd drop to test.
Thanks for your help. Until I get a handle on the test results, I don’t see much point in sending in the results. Hope I can go over your block of 21 days and get some answers with more accurate readings.
That’s a great question! The 15% variance is only tested on the same meters, not as a comparison between meters, so in that case it can be ‘normal’ for two meters to vary substantially. This is obviously not helpful but the best recommendation is to use the same meter for your testing. If you are going to use 2 meters, label your results with each meter so at least you can track patterns in your numbers, since looking at this is the most important thing. Not sure why the second drop was recommended, as first drop should be sufficient.
Hi Jedha.
I’ve dumped the CVS meter and am using the Verio meter. I tested it with the “control solution” …it’s working within the perimeters, so now I can get back to the program!!!
I’ve spent my days downloading DMP recipes, reading, shopping, reading, cooking, more reading and EATING this new diet. So far so good. I’ve managed to average 74 carbs per day for 11 days and my #s are all looking better. FBS this am was 108mg/dL, BEST EVER! I’ve actually logged <99mg/dL 4 times during these past 11 days. My progress is phenomenal considering its only been 11 days so I'm counting on getting ALL my numbers back to "normal/healthy" ASAP!
We're packing up to spend the summer in Montana, off the grid, so I'm going to have to work extra hard to keep on program. Fresh vegetables will be an hour away so wish me luck and I'll check in when I can. Sometime in August I'm planning to write a whole bunch about this fantastic program and all your efforts to "make a difference" for the diabetics in this world.
Thank you, Chris
PS: I glanced through my Kaiser "How to be a healthy Diabetic" book…OMG, the volume of food is totally unbelievable, I had a really good laugh.
YES! It is phenomenal in such a short time but we see these type of results again and again when people change their diet. And of course, when people are committed and motivated like yourself, then things can change very quickly. Without a doubt you will achieve those normal numbers! Are you a writer Christine? Helping us spread the word so we can help more people is great – thank you. :)
FBS 135.
Fasting BS in the am 166? took it again before dinner 87 and 128 2 hous after dinner… people often test 2 hours after the first bite of a meal? don’t usually test more than 2x daily… will talk w my doc about that.
I have been trying so hard to read read read all that you publish… I am focusing more on preparations… which is really taking time out of my day for sure…. but hopefully when I get used to things, it will be easier. a big thank you for sure… I have a long way to go, but I am sticking with this…
Well done Alice. Yes, adjustments do take time but things do definitely get easier. Did you see our info on fasting BS a couple days ago? Here’s the link. That’s correct, after meal sugar levels should be taken 2-hours after, timed from the first bite of food. You don’t have to test more than twice a day but some people do, often it’s a matter of personal preference, not necessarily doctor recommendations. Twice per day is great and sufficient to give you ample information to work with. :)
Check in on day 7
Yesterday I was out running errands and at lunch we stopped at Wendy’s. I had a double cheeseburger (no bun, ketchup or onions) and a side salad. I wasn’t able to test until about 4 hours later at which time my sugar was 137. Can’t honestly say the last time I saw a number that low!
Thank you for the information you have been sharing during this 21 day challenge. It has been very helpful.
Good choice Terri – there are usually options to have no matter where you are. ;)
Did you find any research on continuous bg monitors? I used the Medtronic brand for 8 years. It was only accurate around 100. I needed something to accurately alert me of highs and lows. My favorite is the Dexcom, but it’s a little pricey. You get what you pay for, because it was always within single digits of my finger stick meter. Right now I’m using the Libre. It doesn’t seem to be as accurate as the Dexcom but is far more accurate than Medtronic. This is anecdotal. It would be interesting to know if someone has done a study on this. Thanks
No I didn’t but will take a dig around and see if anything comes up – it definitely would be interesting to see any research findings on these too. Thanks for sharing your experience.