Questions about meter accuracy

Hi everyone,

I'm a recently diagnosed T2 and I have a couple of "newbie" questions. (First for all - I hope this is the correct way to post a question... if not, please correct me!)

Background: I've brought my fasting BG down from 175 (initial lab value that got me diagnosed) to where I am now averaging in the low- to mid-120s with a low carb diet, weight loss and exercise and 500 mg metformin. My doc as has asked me to test fasting, and after lunch and dinner. Since I am so new to this (and I am a bit of a data geek) I bought my own strips to I could test more often.

1. What strategy do you all recommend when you get BG readings that are inconsistent?

Some mornings I'll test and get 165 - yikes! Then I'll test again immediately (because it is so out of range), and get 116. Well, now I have to test again, because which one is right? Pretty soon the strips are piling up and my hands are getting dried out from all the washing...

Now I come to find these home BG meters are notoriously inaccurate, or perhaps inconsistent is a better word. I just switched from the OneTouch Ultra Mini to Aviva Accu-Chek, and I am seeing a lot of variation between the two devices, sometimes I see variation from one finger to another, or one hand to another. What's a sensible approach that will help me get a good sense of what is happening with my BG, without driving myself nuts?

My goal is to understand better the various factors that affect my BG (at least those over which I have some semblance of control!).


First let me say that you appear to be on the right track with your diet and exercise. 25 pounds since September is a real achievement. Slow but steady weight loss is the goal.

Meters may be off by as much as 20%. Unfortunately we have no choice but to accept the reads we get. I usually accept mine at face value unless it's way off from what I expect such as your 165 fasting read. External factors such as something on you hands can effect reads. If you had just handled a glazed doughnut you might expect a high read. Variations in meter reads are a big frustration for most PWD. A lot of folks will do a test just before blood is taken for lab tests so they can compare the read for meter accuracy

Type 2's not on insulin don't require an excessive amount of testing but it doesn't hurt either. Testing for non-insulin dependant T2's does not tell you what you next immediate action is but rather tells you how you're doing. It helps you and your doctor to decide your future treatment options and shows you the effects of what you've been doing. Morning fasting is the most important and after meal testing is a good idea. For after meal testing 2 hours after the meal is the most recommended time. It gives you an idea of how your system has responded to the carbs you ingested. After 2 hours your bg should be back to near pre-meal levels but maybe not quite completely.

I think you're off to a good start. Please feel free to post anytime, that's why this site exist so that we can help each other.

I am convinced that different people find more consistent results with different strips due to their individual blood chemistries. I had very inconsistent and inaccurate readings with onetouch strips, but many members here swear by them. I’ve actually found the most consistent and repeatable results with generic truetest strips, personally. I think the important thing is to not try too hard to find a perfect one because they don’t exist, try a couple different ones that fit into your insurance plan or budget, then pick one and stay with it for a reasonable length of time so you’re not comparing apples and oranges

Finger stick BG meters depend on the percentage HEMATOCRIT in the sample and when the sample is drawn into the strip it will very because blood contains several components that separate almost immediately when the sample is taken out of circulation then hematocrit is effected buy gravity and surface tension. The hematocrit is the proportion, by volume, of the blood that consists of red blood cells. The hematocrit (hct) is expressed as a percentage. For example, an hematocrit of 40% means that there are 40 milliliters of red blood cells in 100 milliliters of blood. Some meters can compensate for Low or high hematocrit. Here is a photo of two meters that I used when my hematocrit was 27.6 and 37.0-50.0 is normal for a man and a women is slightly lower . LifeScan calibrates their home meters at 40% hematocrit and they do not compensate. The LifeScan Meter is off and the Contour meter is only a couple of points from a lab test that was performed at the same time. I have used LifeScan meters since the first paper strip meter and they where always close, when my HEMATOCRIT dropped after my transplant my blood sugar was always low and we discovered that my Life Scan Ultra Link meters where constantly overstating my BG buy 30% or more and the higher my BG was the farther off the LifeScan was , I was constantly over dosing my insulin after coming home from the Hospital....I change meters and the problem was solved.

You are on the right track.

I find that if I test twice (I use AcceChek) the readings are consistently about 20 points different. I rarely retest, unless I think something just cannot be possible. However, it usually is. I am more relaxed about the accuraacy of the test results in general, because when I was diagnosed there were no home glucose testing kits, so what I can do today is fantastic.

As far as are not on insulin. As a result you need to refine your diet, so it includes the same carbs, proteins, fats, etc every day. Have you seen a dietician? That might really help. Usually, a diet plan will be created then refined to stabilize your reading. You are having different fastin readins, as you are not eating cinsistently the same thing the day before, or you have or have not exercised.

You are doing well and diabetes is a total learning curve, so hang in there!

Thanks, I appreciate all the information, and I can already tell that this site is a fantastic source of information and support.

Thanks for the tips - I think sometimes, because my hands tend to be cold in the morning, I squeeze too hard to get the blood out, and/or I have to stick myself multiple times to get anything. Being more rigorous abut making sure my hands are warm before beginning will probably help.

Thanks. I am mostly trying to understand how the factors that I have any control over are affecting my BG. I track all the nutrients in what I eat to a pretty fine level (for both weight loss and BG control), so I have a good handle on "what". But eating at consistent meal times is a challenge, and figuring out how to alter my intake on my heavier workout days is also something I haven't been very successful with yet. I have an appointment with a diabetes nutritionist later in December, so by then I was hoping to have a good sense of what seems to work and what my real concerns are.

The only measures I have now to asses my progress are the scale (weight is coming off steadily, so that is good), the BG readings (trending steadily lower, but with these occasional possible outliers or possible real bumps up) and how I feel (pretty good except for frequent headaches).

You are right - it is a total learning curve!

Thanks for all the advice!