First, remember that blood glucose is an ever changing thing. Your blood sugar is always in a process of flux. Imagine climate change (in a non-political way, remember that if climate change is man-made or not, it still is always naturally occurring in the environment). Like climate change on Earth, your blood glucose is always changing. Your body is usually attempting to create insulin or burn sugar. You are an oven and glucose is your fuel. How fast can blood glucose change? Well imagine how quickly it takes a drug to have an effect on you after you’ve consumed it. Alcohol, for example, can change your behavior rather quickly. Now imagine that alcohol was delivered directly to your blood stream. It would be almost instant. Now realize that insulin is released in spurts at regular intervals and instantly affects blood glucose. Glucose, second to second, is always fluctuating. You can never take a test back to back and expect the same results. If you did, you are the exception, not the rule.
Now think of the sample size one is testing when they test their blood glucose. Your body has a lot of blood, gallons in fact. The average human has about 1.5 gallons of blood and that scales up with weight. How many test strips would it take to test every drop of 1.5 gallons of blood? Easily millions of strips. So, you have a very small sample size relative to the overall body of blood. Like air circulation in a home, where certain spots may maintain a different temperature, your blood will maintain different blood glucose amounts depending on where you test. If you test on your foot, will you get the exact same blood sugar reading as testing on your arm? There are ebbs and flows to blood sugar in all parts of the body and that is a problem when you are using a 1/100000000 sample size.
Think of it like a political survey. If you ask 10 people, you will get a result, but you may need to ask 10,000 people to get a result that is accurate or representative of your overall blood glucose. In a lab, do they take a miniscule drop of blood, or a large sample? In a lab they take a vial of blood.
So why use such a small sample size for testing glucose? Glucose testing must use significantly less blood than you generate or you run the risk of vitamin deficiency amongst many other problems that having a consistent bleed will cause. When some patients must test 10x a day 365 days a year, you understand why we keep the samples small.
Finally, imagine the market. The creators of a lot of blood glucose products do so in a way that is low cost, but also low risk. They would rather create meters that are slightly positively or negatively biased depending on how their legal departments perceive the threat from inaccuracy(or how costly it is to calibrate each meter/strip). That is why some brands, and indeed some runs of meters within a brand will be what we call “positively biased” or “negatively biased.” The numbers are pretty small, but when you consider the already inaccurate nature of blood glucose testing you can see how this only adds to the preconceived notion that meters are inaccurate. Especially when a patient is switching brands and suddenly their sugar is 30 points lower on average then they are used to Read More.