Dexcom 7: We’re done, we’ve split, don’t call me – at least not ’til you’re older

My Dexcom 7 CGM and I have had nine days and nights together and we’ve parted ways. And, as if it knew I was not happy with it, it gave me one last kick in the teeth coughing up its last numbers.

I met a friend today for brunch in Manhattan. I walked from my apartment in Brooklyn over the Brooklyn bridge and then took a subway to the cute little Italian bistro  where we were meeting. The walk  took about 90 minutes.

After being seated and looking at the restaurant menu I took out my meter and tested. I was “80.” I took the CGM receiver out of my pocket. I was “80.” Unbelievable! This is the first time since CDE/Pump Trainer, Gary Scheiner, slapped the sensor pod on me last week in Philadelphia – and I carried it across state lines – that both showed the same number.

I know the CGM’s numbers are not expected to match up precisely with your meter numbers. I know the CGM tests interstitial fluid and not blood glucose and there’s a difference. I know there’s a lag time on the CGM of 15-20 minutes. I know you’re not supposed to make dosing decisions off the CGM. I know that meter readings vary up to 20%. I’ve also learned that means if you test on your meter and get 80 and you test immediately again, you might get 80 or you might get 68 or 92 or 104. I know all this, yet after its first week of so many misses, the CGM immediately won back my trust, and my hope, with that “80.”

Two hours later after a fairly low carb lunch my friend and I were strolling around and the CGM read “180.” Hmm…I thought, well I did have a few roasted potato pieces and a half a plain cookie the waiter brought along with the bill, maybe I need another half unit, so I took it. Then my friend and I spied a new concept yogurt store where you make your own frozen yogurt and toppings so of course we had to go in and see. And we had to put that tiny paper sample cup under the raspberry and peanut butter yogurt.

Now walking back to my friend’s car I reached into my pocket to see what number was on the CGM. It said “222.” Hmmm…well I had just had what was probably a quarter cup of frozen yogurt, guess I need another 1/2 unit, which I took.

Sitting on the subway platform 15 minutes later waiting for my train home a thought came barreling through my head…hmmm…”222″ … I’m hardly ever over 200. Let’s see what my meter says. My meter said, “108.” My meter also said, “What the hell are you doing dosing off your CGM!!! You know better than that!!!” Surely I do, but I had forgotten in the romantic glow of that “80” when the CGM won my heart back at lunch. I so wanted to be in love with my CGM just like the many people I’ve talked to are with theirs.

I pulled the CGM display out of my pocket and went to enter the “108” to calibrate it and it gave me an error reading. It actually said, “ERR” which is just how I felt, especially if you add a few exclamation marks, “ERR!!!.” When I got home a half hour later, I looked through the booklet and saw my sensor was done, and it had had the last laugh all the way to its untimely end.

A CGM? Not for me. Not until its accuracy is twice what it was for me. About 50% of the time it was tracking 10 – 20 points apart from my meter, the rest of the time it was anywhere from 20+ to 75 points away. It alarmed me telling me I was “53” when my meter said “85” and it fooled me into trusting it so many times.

I wanted to love you CGM, truly I did. But I’m going to wait til another generation or two comes along. Until a CGM is really ready to love me back. For now I’m sticking to finger sticks, and running for the juice!