Welcome back to another Saturday edition of Ask D'Mine, our weekly advice column on anything and everything diabetes -- hostedAsk-DMine_button by veteran type 1 Wil Dubois, a diabetes author and community educator. The Diabetes Online Community is just wrapping up a special Diabetes Art Day this past week focusing on test strip accuracy, and in keeping with that theme, we have a trio of questions today on the issue of how our meters and test strips give us data about our diabetes management.

{Got your own questions? Email us at AskDMine@diabetesmine.com

Martha, type 2 from Ohio, asks: Why do some meters need to be "coded" and others do not?

Wil@Ask D'Mine answers: You are sooooooo not going to like my answer. Coding is a manufacturing workaround for poor quality control. Or at least, it was a way to account for "variations" in different batches of strips that may affect testing accuracy, the vendors say.

To illustrate how this works, let's suppose—and I'm just making these numbers up—that a given batch of strips reads 27% high. The batch is assigned a code number that tells the meter: test the blood; then lower the result by 27%. Another batch might read 18% low. That batch is assigned a different code number that tells the meter: test the blood; then raise the result by 18%. The code number might be put on a computer chip that plugs into the back of the meter, or it might be a number printed on the vial of test strips, and the PWD needs to enter the code number into the meter using arrow buttons on the face of the meter itself.

The problem with the coding system is that people tend to forget to change the chip or enter the new code number when they start a new batch of strips, right?

It doesn't take much imagination to understand how using a coded meter with the wrong code number can get you into a world of Coded Stripshurt very quickly. If you combine, say, a batch of strips that already reads high with a wrong code number that tells the meter to adjust the results still higher, you can get results that are worlds away from reality. Of course the same thing can also happen on the low end. According to one study, a mis-coded meter can be off by as much as 224 mg/dL.

Holy crap!

And it's too far off topic for today, but there are also issues of strip-to-strip variability within lots, alleged mismanagement of batch testing in some plants, and outright cover-ups of adverse events from bad strips. For more on all of that, and to find out what you can do to help change the status quo, see "Saint" Bennet and D-Company's Strip Safely campaign.

But back to the whole code or no code thing.

Is it really that hard to make a strip accurate? The short answer is: it depends. Back in the olden days—a few decades ago—the enzymes used to make strips were harvested from microorganisms, and the purification technology just wasn't good enough to nail down consistent quality. All strips had to be coded. As time went on, purification techniques got better, and later still, the enzymes could be built using recombinant DNA methods, much like our modern analog insulins. So "perfect" strip enzymes can now be produced in an assembly-line fashion with no lot-to-lot variation (at least in theory). That's why we now have a variety of no-code meters to choose from. If the strips are consistent from batch to batch, there is no need for coding. So really, on a technical level, the coded meter is now as obsolete as an 8-inch floppy disc.

So why do they still exist? The coded meters, I mean, not the 8-inch floppies. And why are we seeing a rise in the old school code-required meters and strips being "preferred" by many health plans, especially those for seniors on Medicare? I submit the answer is greed. Just because you can do it better, doesn't make it cheaper.

Making something sloppier is always cheaper than making it well.


Edward, type 2 from Idaho, writes: I'm confused, my new meter is not supposed to need to be coded, but there's still a code number screen that pops up. Am I doing something wrong?

Wil@Ask D'Mine answers: No, you're not doing anything wrong. You were prescribed a Phoenix. You know, the bird that reincarnates itself out of its own ashes? Let me explain.

No Coding StripsAs we talked about above, there are meters that need to be coded, and meters that don't. Meters that don't need to be coded are very popular with healthcare professionals, because code-requiring meters that are mis-coded can be hundreds of points off, which makes them dangerous to patients. That means no-code meters get prescribed more often, and therefore (prior to recent changes in health insurance coverage) outsell coded meters, which in turn means meter companies with only coded meters have a sales problem. They need a way to compete, and because getting a new meter through the FDA is both time-consuming and expensive, some of these meter makers came up with a functional workaround: They decided to make all their strips use the same code. This lets the consumer use an older-school meter, but never have to change the code. It's sort of a fake no-code meter. A unicode meter that combines quality strip manufacturing with old-school gear.

In theory, there's nothing wrong with this approach to "creating" a no-coder from the ashes of a coded meter, like some sort of blood-sucking Phoenix. But in reality, there's a problem. The code can still be changed on the meter, and that introduces errors. In point of fact, I've seen at least a dozen of these "coding-free" meters that have been accidently code-shifted by patients. The code screen still flashes at the start of the testing cycle, and if you happen to have your thumb on one of the arrow buttons when that happens, you can inadvertently change the code.

Personally, if I were King, I'd outlaw, then banish, all coded meters from the Kingdom. Both the ones with variable strip lots, and the ones that use "modern" strips in a recycled coded meter.


Bonnie, type 1 from Georgia, asks: Is there a valid reason that strips come in boxes of 50 and 100? The math never works out with the common testing frequencies.

Wil@Ask D'Mine answers: Let's see.... The one test a day that is covered by most health insurance plans for folks on orals works out to 30 strips per month or 90 per quarter. Neither number is divisible by 50 or 100. The three times a day that is covered by most insurance for folkStrips in Vials on insulin works out to 90 a month or 270 per quarter. Neither of those numbers is divisible by 50 or 100, either. The six times a day usually recommended for type 1s works out to 180 per day for a month or 540 per quarter. Also not divisible by 50 or 100.

You're right, the math never comes out right. To be honest, I have no idea where or how the 50-and-100-count test strip vials came about (and 25-count vials are also seen in some brands, too, by the way). It's a good question, and to be honest, one I never thought about before you wrote in. And I searched high and low, but could not find an answer for you.

But just so you know, this issue isn't limited to strips. Most pills come in 100-count bottles, but you just never see them because the pharmacies break them down and dispense just what you need (read that to mean the bare minimum that your frickin' health insurance will pay for—don't drop one in the toilet!). But you can't breakdown a vial of strips and dispense just what the doctor ordered into a little brown plastic bottle because strips need to live in their protective vials in order to keep in good working order. You could probably make a killing inventing a cheap a universal test strip vial to sell to pharmacies.

The choice of how many strips to put in a vial could be an evil plot on the part of the strip makers to force the health plans to pay for a few more strips than you "need": or it might just be, that as no two PWDs need or use the same number of strips per month anyway, there's no realistic way to match the vial volume to the prescriptions, so they had to pick a number — a nice solid 25, 50, or 100. Who knows why?

I guess when it comes to picking random numbers, tradition probably rules the day...


This is not a medical advice column. We are PWDs freely and openly sharing the wisdom of our collected experiences — our been-there-done-that knowledge from the trenches. But we are not MDs, RNs, NPs, PAs, CDEs, or partridges in pear trees. Bottom line: we are only a small part of your total prescription. You still need the professional advice, treatment, and care of a licensed medical professional.

Disclaimer: Content created by the Diabetes Mine team. For more details click here.


This content is created for Diabetes Mine, a consumer health blog focused on the diabetes community. The content is not medically reviewed and doesn't adhere to Healthline's editorial guidelines. For more information about Healthline's partnership with Diabetes Mine, please click here.