PDM Consistently low

I have been having some issues lately with the blood sugar readings I get from the PDM as compared with what my Dexcom reads or what another meter reads. The PDM was always low. Today it was so far off from the Dexcom it forced me to pull out the bottle of control solution and do a side by side comparison. What happened shocked me and made me wish I had done the test months ago. Insulet is sending me a replacement PDM which I will have tomorrow. I will do the same control test with it before even beginning to set it up. Some people say - "I use calibration code 17 or code 12 and that is how I get around the problem". But the fact is the Abbott strips are coded 16 and if one has to change the code at all in the PDM then it is not working right.


There is a known bad batch of test strips that read WAY too low. Abbott issued a recall for that batch. You might want to check the lot numbers against the recall.


That said, the standards for test strips are very loose.... that's what the "Strip Safely" campaign is about ... to tighten up the standards for meters and strips and require ongoing quality control

Thanks, I checked it out and the lot number is not on the list. I understand the laxity of test strips standards, but at the same time, I also read that Abbott was among the leaders in making a good quality, accurate, consistent strips. When the Insulet customer service rep took the report she asked me the lot number on the strips so I figure she too cross checked it against the list.

This happened to me a couple of months ago, too. Exchanged the PDM 3 times with Insulet because they all read very low - even with control solution. Ultimately, I think I had one of the bad batches of strips, but I find that the PDM still reads 10 to 20 points lower than other meters. I've heard that some people use code 17 or 18, instead of 16 and that seems to adjust for a more accurate reading. Very frustrating and worrisome. Hate to be treating a low that you really don't have.....


Adjust your meter to 17 or 18 and retry your test. I was on 17 and it was closer but still low. I'm on 18 now and It's very close in good range, but as it goes higher it reads higher, which I don't mind so I kept it there.

Thanks Scott, while that would certainly provide a temporary fix to the problem, what happens when I open a new batch of strips ? I don't want to have to continually change the calibration code on the PDM and nobody should have to do that.

Are these 'Abbott Freedom Freestyle' test strips or 'Abbott Freedom Freestyle Lite' test strips? I notice you are using 'lite' meters in the second photograph.

As HPNPilot implied; the readings are all in range - +/-20% or +/-20mg which ever is greater. The error is actually at least 9.5%, which is not likely to get us any sympathy from the industry.

The problem here is that the error is systematic - the Abbott implementation is consistently showing rising blood sugar around 90-100 and the Insulet implementation of the same blood test technology is showing the same around 65-70; significantly below the Abbott value.

I'm not going to quote the exact amount below because the marketing men we have to live with don't understand the math, let it be sufficient that it is significant.

My reading of the things other people have said is that re-coding the Insulet meter might be a reasonable approach. What worries me is that the coding correction over the range (like, we're diabetics, 30-600) might not be consistent.

For the math geeks, the coding is either a slope or an offset, or quite likely, both, but we need to do a proper curve fit to the basically linear math in the Omnipod PDM. Life sucks, then you're a diabetic.

They're Freestyle strips not the lite ones. And I know the 2 meters are the Lite variety but I have found the strips for all of them are pretty much equivalent in accuracy. Or at least they are all pretty close to the dexcom sensor which I have found to be remarkably accurate. The only one that isn't accurate is the pod PDM. And I don't want to change the calibration of the PDM to make it more accurate. I want it to be accurate on its' own.

An update to this post. It was the strips. The problem for me was the strips I have been using for the last couple of months have been fine in the meter, but low in the PDM. It is Freestyle lot #1361642. Here is a control test of that batch and a new lot of strips I pulled out of my stash. Pretty clear evidence in my opinion.

Glad to hear it's not the PDM.

As an aside ... you surely do get a lot of blood on that there strip! ;)

Good thing that's control solution :)If I needed that much blood each time, I would stop checking all together.

Aaaaahhhhahahaha. Yeah, that would be bad.

(I don't know what "control solution" is ... guess I should find out, eh?)

Control solution generally comes with new meters. There is a High control, Normal control and Low control solution. Each can of strips has a range for control solution on it. So if you think your meter is not accurate or is not performing properly you do a test with the control solution. If the result falls within the range on the can - like in my case the range for "normal" was 76-114 then your meter is reading correctly. If it falls outside the range then there could be something wrong with the meter. Or in this case with the strips.

That's interesting. The lot-to-lot variability issue with regard to meters is known; the original German study which has been used repeatedly by the various pundits to criticize accuracy used tested only one test-strip lot per meter. In that test the FreeStyle Freedom Lite and the FreeStyle Lite (but not the FreeStyle Freedom) test systems were evaluated and both had good accuracy overall.

A second German study which was actually published at the same time tested for lot-to-lot variability of a smaller number of systems. Four different lots of FreeStyle Lite were tested and the newly tested 3 lots all performed much worse than the first lot tested! Two of the lots were reading between 7 and 10% low and lots test strips were much less consistent overall - with a variability of +10% to -20% on individual readings.

What you have demonstrated is that simply changing the meter can also change the results.

The second German study is by far the most important of the two, because it effectively invalidates the results of the first study; the first study used only one lot, but the second shows that just using one lot produces unreliable results.

I find the lot-to-lot behavior very worrying. We can deal with systems that consistently read high or low. People have suggested changing the coding on the PDM because of a perception that the Insulet meter reads low. We can deal with systems that produce random large errors - the Federal Standard allows large errors in 1 reading of every 20, but if in doubt we just re-test (which reduces the chance of a random error to 0.25%).

What we can't deal with is a system where a new lot of test strips consistently changes the BG readings by as little as 10% either way, because that adds up to a potential 20% difference in my BG management between successive lots of test strips. I might easily go from targeting 110 mg/dl to targeting 90 mg/dl just because I opened a new box of test strips.

The control solution can help some, but the range on the package corresponds to the absolute maximum allowed by the standard. It's basically 80mg/dl to 120mg/dl for a 100mg/dl control. If that was allowed (it isn't) I could easily run with a blood glucose of 60mg/dl and think I was just fine. (This wouldn't happen because I know, but lots of us are hypo unaware.)

You first lot was way outside the limits permitted by the standards. You had a 96mg/dl solution, the standard requires 19 out of every 20 readings to be at or above 76mg/dl. You were able to consistently show readings below that. Unless I'm missing something that is a really bad violation of the current standard.

John Bowler

I have contacted Abbott about this and they are replacing the strips and are sending me a return envelope for the strips that are unused. I have gone on the FDA MedWatch site and submitted a report to them regarding these strips. I have contacted Insulet about the PDM reading low because I really think this lot of strips should have been recalled along with the other 20 lots that Abbott recalled.
You're not missing anything, it is a really bad violation of the current standard and the worst that will happen is Abbott will have to replace some strips.

Good, and thank you; that's what MedWatch is for.

I did not get the same indication you report. My new Omni, old Omni, and Freestyle Lite using the same Freestyle strips, read very close. Not enough difference to cause a mis-diagnosis by me. I did take your letter to heart and did call Abbott and they will replace all of the strips I have. I am hypo-aware, so I would know if the meter was reading low. But I agree with jbowler that not everyone is.
Thanks to you two for keeping us on our toes!!

Ummm you are basically contradicting yourself with your statements and observations and what has been reported as the error these strips give.

If you are hypo aware or not makes no real difference on this issue because the meters/strip combination is regularly reading LOWER than the real blood sugar level, so worst case, you eat a bit more sugar than you should because you are warned that it is too low and you take the extra precaution of taking extra sugar.

The real issue with these strips is that you blood sugar is actually HIGHER than what is being reported by the meter, so you are constantly not taking enough insulin to counter the high bg readings. IE, meter says 150, when your bg is actually 180 or higher, but since it says 150 you only take enough insulin to drop that bg reading by 30 to get to the 120 target, instead of 60 that you should be reducing it by. Thus, you end up with consistently higher bg than you want/need/think you have, and for ME, that means I am in danger of going into keto-acidosis much sooner than I should.

Still, all in all, it is not that big a deal, and typically is only a difference of one unit or less to cover the difference between target and actuality.

Fortunatley, they are sending 4 boxes of new strips or 400 total strips, which saves me a bit of cash out of my pocket for about 2 months or so. I just wonder if they will eventually be replacing my "new style" pdm with one that actually works? Bad pods, bad meter in the pdm, how many failures are we supposed to accept from these folks... the expense is really high to throw away pods and insulin due to systemic failures, but now strips too?

I was just saying that I get no significant difference between the only 3 meters I have available to me, old Omni, new Omni, and Freestyle Lite. I would know if the meter said I was 60(but my real BS was higher) because I am hypo-aware. I have not experienced the low reading that some have experienced. Abbott has recalled all of their strips and they say it is a strip problem, not a meter issue. Hope that clears the air about what I said. We are all different and have differing issues with this crazy diabetes.

My PDM has consistently been 20-30 points lower than my Dexcom CGM. For years. Also, I have compared lots of times against an Accuchek Aviva and a Freestyle Freedom, and those were always higher - and consistent between those two. Since I have a baby diabetic, I didn't really care because we run him higher anyway and it gave me a heads up on a low BG on a child that can't talk. And if I got really concerned, I would just change the code to 17 and then all three meters matched.

Note on the current test strips - according to Abbott, the only meter that will give you a confirmed accurate blood sugar with the current regular strips is the Freestyle Freedom - not the Flash, the Lite, old PDM, new PDM - just the separate Freestyle Freedom meter. As always, YDMV. I tested it again last night - PDM 116, Freestyle Freedom 138.

I think this has been a long standing systemic problem. I am glad the Strip Safety campaign is around, because I am sure they had something to do with this. Abbott is going to be lucky to escape without any lawsuits IMO.