The Life of a Meter (continued)
Testing The Meter and Teststrips
In theory, you can check a meter with test solution to see if it's working correctly as it ages or after its been microwaved or dropped in soapy dishwater. Test solution is fake blood with a fixed glucose content. The idea is that you put a drop of control solution on your finger, then test the glucose level of the test solution just like you'd test your blood, then compare the results to a reference range printed on the vial of test strips.
Personally, I think test solution is a waste of time and a test strip. Here's why. Looking at the reference range printed on the vial of strips I'm carrying with me today, I see that the range is 105 to 159. If I've done my math right, that means my meter could read either 20 percent low or 20 percent high and still be considered to be working correctly.
It could be off 40 percent and still be considered to be functioning?
You've got to be kidding. I think the best assurance that your meter is working right is to simply replace it on a regular basis. Ah, and never buy a meter. As the profits are in the strips, the meters are free for the asking.
That takes care of meters, now what about the test strips themselves?
Test strips, like milk, come with expiration dates. Of course, with a gallon of milk, the date is officially a "sell by date" which means that it's still good to drink for a week or so afterwards—usually preceded by a cautious sniff. The problem with test strips is that you can't sniff them to see if they've gone bad. But they can't work just fine one day and be wildly off the next day. There must be some padding. Some margin for error.
That said, test strips are made of stuff that'll go bad in time. They can't last forever. If your strips expired yesterday and you still have ten left, should you use them? Absolutely. If they expired two years ago? Ummmm…. I'm thinking not.
So the guideline I'm about to give you isn't the result of any scientific study, but is just from observations I've made over the last few years. I wouldn't use them more than six months beyond the expiration date, and for the last two months of that time I'd be cautious about a reading that seemed funky.
Storing Your Strips
Oh and one other thing: Storage affects strip life. Let me tell you the Ziploc Baggie Story. One day last year I got a panicky call from a lady who runs a day care center. Her blood sugar readings were suddenly crazy-high. Odd, as she'd been long-term stable and well controlled.
I drove over to the center, and surrounded by delighted, screaming pre-schoolers (who stole my stethoscope), I downloaded her meter onto a netbook. Sure enough, her numbers were crazy-high. And sure enough, it was a night and day difference. One week she was doing great, then BAM!
WTH? I wondered as a small child climbed on my lap and attempted to borrow my glasses. At this point I could feel my own blood sugar rising, but the woman had done this work for years. She sat calmly in the chaos, clearly acclimated.
So I ran through the normal check list.
Elbows with Fresh Spinach Tuna Salad with White Beans and Tomatoes Peanut Chicken Kabobs Poached Halibut in a Mushroom Sauce Butter Cream Frosting Beef Wellington Honey-Glazed Oat Muffins Grilled Fish with Roasted Jalapeno Rub Chickpea Salad with Tahini Dressing Carne Adobado (Spiced Pork)
When the Dexcom monitor flashed a warning that it was time to order a new transmitter, I figured I’d at least have a couple of weeks before it went kaput. So we numbed the back of Charlie’s arm for about 40 minutes, slapped the sensor on him and waited two hours for the warm-up period. And waited. And … waited. Unlike the signal spottiness we experienced occasionally when we were using the Medtronic CGM, the Dexcom...