August 11, 2008

Strange Readings? Check Your Meter Battery

They say a man with two watches never knows what time it is. If you have two meters you may sometimes feel the same way about your blood sugar readings.

This past weekend I was seeing some really odd readings with my usual Ultra 2 meter--I was low carbing and using my usual dose Levemir but my fasting blood sugar was much higher than what I expected to see--113 mg/dl rather than low 90s or 80s.

Then I remembered something: when I had been out on a long walk the previous day and tested my blood sugar with the Ultra I keep in my purse, it had been 80 mg/d, but when I tested at home a few hours later without eating anything, it was back into the low 100s.

Finally I got the bright idea of testing my blood sugar simultaneously on both meters, and yes. The Ultra 2 was reading 113 and the purse Ultra read 90. In the past when I have tested the same draw on both meters they have matched within 3 mg/dl.

I did a control solution test (though I have NEVER yet had a control solution test identify a faulty meter, even when the meter has been found to test 50 mg/dl higher than a lab reading.) The control solution test showed the one meter reading considerably lower than the other when tested with the test solution, but both meter readings were within the ridiculously wide range supplied by the meter manufacturer.

Then I remembered that I had read somewhere that a battery is only good for about 1000 readings. Since I test about 5 times a day, that is not even a year's worth of tests. So before I went out to get a new meter and then had to wait months for the rebates involved, I figured it would be worth investing $2.49 in a new battery to see if it made any difference.

I installed the new battery and tested again. This time my two meters matched within 1 mg/dl. And they matched at the low reading, not that baffling high reading.

Problem solved.

But once again I was disgusted at this latest proof of how poorly designed these meters are. The weak battery had caused my meter to read 24% higher than it should have read, but there was no "low battery" message on my meter though the manual tells me there should be one when the battery is running low. I had definitely run more than 1,000 tests on this meter, but obviously the meter will continue to provide test results--erroneous test results--long after that number of readings has been exceeded.

Even worse, had I not had a second meter with a newer battery, I would not have discovered this problem and I might have ended up using too much insulin as I tried to get my fasting blood sugar down from the "high" of 113 to the normal middle 80s range I shoot for. Since my 113 really was 90, lowering my fasting blood sugar by another 20 mg/dl would have put me at risk of hypoing.

From past experience, I know that calling the meter company to complain would have only resulted in the phone-clone demanding that I do a control solution test and when the value fell within the 35 mg/dl wide range given on the vial of strips, they would have told me there was no problem.

But if there is a 35 mg/dl difference between what your meter says your fasting blood sugar is, and what it really is, there IS a serious problem. Not to mention the 7 expensive expensive strips I wasted on debugging this latest problem.

In a world where every other piece of electronic technology drops in price every three months, and where one out of every U.S. four adults over age 50 has diabetes and is hence a customer for the blood sugar meter companies, there is no excuse for the combination of poor performance and rising prices we continue to experience with these meters.

The meter is the single most powerful tool we have at our disposal to help us for achieve normal blood sugars. Isn't it time to demand that they work properly and that the companies charge a fair price for the strips?


Pax said...

heres hoping my recent high numbers will be a meter battery

mine is too new to, for me to have suspected that

my real reason for this post is, where do you get the one in four over fifty number, are diabetic, usa, jennifer??

love your work, have and have read your book. Thanks
just bill

Jenny said...


I saw that statistic somewhere recently, but can't track it down now. For a link to the the most recently published CDC statistics not broken out by the older age group:

Click HERE.