July 8, 2012
Why Can’t BG Meters Tell Me My BG levels?
This blog upsets me in so many ways. First, blood glucose meters are just that; designed from the beginning to read the blood glucose levels from the test strips containing a sample of your blood. Sugar is sugar and not blood glucose. Sugar is a carbohydrate and is converted in the body to glucose.
Why do writers of articles and blogs make the assumption that blood sugar is blood glucose? I would guess because they do not understand the chemistry that takes place and think they are doing their readers a service. This also means that they do not understand diabetes equipment; correct, they do not understand or even know about their diabetes equipment. Even this type 1 writer does not know diabetes equipment, just how to con readers and attempt to sensationalize something. It is this type of misinformation that creates problems for the rest of us with diabetes. And to this, I say BS does not mean blood sugar, but bullshit.
Readers see one person misusing terms and think when they confront others with diabetes that they are knowledgeable. This really makes it difficult for us to educate people about blood glucose and diabetes equipment. In the last week, I have had three panic emails about this post. I have had to explain to people new to diabetes what is really at issue and how to read misinformation like this.
The writer's complaint about the lack of blood glucose accuracy is the only valid point she makes. Even our Food and Drug Administration can't figure out how to solve this. While the FDA does acknowledge that many of us are using our blood glucose meters for tight blood glucose management, the FDA admits this is not the intended purpose. If the blood glucose meters are not safe and effective as they should be, why did the FDA allow them on the market? It is the test strips that need to be more accurate.
Now I know my meter can give me erroneous readings because of expired test strips or contaminated test strips, but when checking it against the laboratory results of a blood draw, my meter reading has always been within 5 mg/dl (0.3 mmol/L) of the blood glucose results, and a few times the same reading. As a result, I have confidence in my meter and test strips – although the FDA says I should not. People that use different meters consistently should expect large variances in their readings. We do not know if the meters used were stored properly or not. We also do not know how the test strips were stored.
The author of the blog laments about the accuracy and further states “we’re on the launch pad for an artificial pancreas — where accuracy will be even more critical — why don’t I have a meter that gives me an accurate reading of my blood glucose.” I say then that they need to have the continuous glucose monitor (CGM) mounted on the fingertips for greater accuracy instead of other places on the body where the readings are always 15 to 20 minutes later than the fingertip readings.
Maybe the FDA needs to withhold approval of the artificial apparatus until the problem can be solved for placing nanosensors in the fingertips and nanofilaments or nanowires under the skin to the CGM. Or maybe a reader of nano or microsensors will be developed to solve this problem. This writer should not have to realize that she is 15 to 20 minutes behind time when needing a reasonably accurate blood glucose reading.
As for meter accuracy distortion, this is understandable when they are jammed into bags, purses, pockets, and other places where they were not intended to be stored or carried. I have seen test strips wedged in the meter slots and jerked out. With this happening and no care of where the meter is stored, it is small wonder dirt, lint, and test strip particles could affect the accuracy of the blood glucose meter. This is delicate equipment and if you want accuracy within FDA guidelines, treats it accordingly. Some people even store meters and test strips in car glove boxes or on the dash in full sun and heat, so how can they expect accuracy?
I can believe medications taken can possibly affect blood glucose readings, but I have no information as to which medications or dosage required. The article referenced mentions maltose given while people are in the hospital. Surprise, maltose and dextrose are commonly used in the hospitals. We should expect elevated blood glucose readings from dextrose and administer insulin accordingly. Maltose does give a falsely elevated blood glucose reading on most test strips. This is why people need to be aware of what the hospital administers. Hospitals are nefarious for not informing patients about medications they deliver and ask patients to take or inject into patients.
I know how improper hand care and washing can affect blood glucose readings, been there, done that. Still people insist on accuracy even though they will not wash their hands or fingers after handling food. Many ignore the fact that they should wash with warm water and soap and dry properly and then declare their meter is inaccurate.
To my readers, please know that there are many variables and that as things currently exist, we have reliable meters and some that are not so reliable. It is the test strips that determine meter accuracy and until our test strips can be calibrated to a more accurate degree of precision, we cannot expect our meters to be any more accurate.
Even I occasionally will have a lapse in memory and say meter when I should say test strips. The meter can only relay what it reads from the test strips. This is the purpose of the battery in the meter to create electronic communication to interpret what the test strip is reporting and translate this information to a reading on the meter. If the meter has dirt or lint in the slot that the test strips are inserted in, then it may be difficult for the meter to accurately read the test strips. The meter just interprets the results of the test strips in a language we can read on the meter. The test solution use to determine test strip accuracy does not change the meter. It can only let you know that the test strips are good or bad. This can happen to a container of test strips.
The meter is calibrated at the time of manufacture and can be altered by improper storage and dropping the meter. The test strip box has an expiration date so that reasonable reliability is maintained. Storing the container in moist conditions or direct sunlight can alter the reliability of the test strips in the container. It is possible for the meter to malfunction or go bad like it is possible for test strips to become unreliable. Proper storage and handling of both is important. Dirty (or contaminated) fingers handling the test strips improperly can affect the readings as can food on the area of blood wicked into the test strip. For more information on storage and use of test strips, read my blog here.
For information, I use the Accu-Chek Aviva meter and currently the Accu-Chek Aviva test strips. I have been notified that the next order of test strips will change to the Accu-Chek Aviva Plus test strips. They will work in the current meter. The notice states, this is to improve the accuracy and sensitivity of my blood glucose test results. The information I was able to locate about the Aviva Plus test strips says, “New generation of test strips offers advanced chemistry and safety for self-monitoring of blood glucose.” The next paragraph states, “The new maltose-independent test strip is designed to prevent the interference of maltose on blood sugar readings which can occur in rare cases when drugs containing or metabolizing to maltose are parenterally administered.” This takes away the concern about maltose above.