Just as Bisi was the one to nudge us into getting her on an insulin pump, she has now pushed us to get her a Constant Glucose Monitor (CGM)—the Dexcom Platinum. I’m not quite sure why she was so insistent about it. An older friend of hers with type 1 has the Platinum, and Bisi heard from her that she wouldn’t have to test her blood sugar as often with it. But with Bisi, so far we haven’t found the CGM to be a substitute for finger sticks. If anything, the CGM inspires us to test more rather than less. At times, the CGM is accurate within a point or two. At other times, we’ve seen it be off target by as much as 100 points, so in those cases if we were using it to determine how much insulin to give Bisi, she’d be in trouble. So it’s hard to know when you can trust the CGM and when you can’t (though now that she’s been using it for about a month, it seems to be getting more reliable). Also, we’re testing more because with the CGM we’re now catching more times when her blood sugar is either too high or too low.
The CGM involves a small sensor—about the size of a Brazil nut—on Bisi’s body, with a thread-like tube that measures the glucose in Bisi’s interstitial fluid, rather than her blood, which is what we measure with the finger sticks. The glucose readings are displayed on a small device about the size of an iPod Nano, which has to be within 20 feet of Bisi’s sensor to work. The readings are updated every five minutes and displayed in a graph. One of the great things about the CGM is that it shows glucose trends. So with the finger stick we just know that Bisi’s glucose level is, say, 93, while with the CGM, we know that it’s 93 and holding steady, or 93 and dropping fast (in which case maybe we’d give her a snack, or turn off the constant drip of insulin she gets from her pump throughout the day), or 93 and rising fast, in which case we’d keep an eye on her to see if she might need more insulin later on.
There have been things I’ve liked and things I haven’t about having her on a CGM. On some nights, the CGM has alarmed erroneously—saying that Bisi’s glucose is low, when a test with her regular meter shows that she’s not. But on a few nights, it has alarmed and woken us when she really was going too low—lows that we would not have caught with our usual regimen of nighttime testing, since she seemed to be at a safe level when we tested her before we went to sleep. These catches make the CGM completely worth it in my book, and well worth the additional hassle of having more data to analyze, more gear for Bisi to wear (a CGM and a pump are a lot to put on a little body), and more day to day worry as we obsessively look at the minute by minute trends of her fluctuating glucose level.
Anyone who has a close connection to T1D knows that at some level you’re always thinking about it—watching for lows, watching for highs, thinking about what you need to eat and how much, wondering if there’s something outside the norm that could be throwing your glucose level off. Still, though, at times diabetes is in the back of your mind rather than the front. You aren’t actively thinking about it every. single. second. But with the arrival of the CGM, I found that Bisi’s diabetes was once again at the forefront of my mind all the time, as it was when she was first diagnosed. It’s hard not to obsessively check the monitor for each new reading. Is she trending high? Is she trending low? How fast is her glucose level dropping? How fast is she rising from that yogurt she ate? Whereas pre-CGM if I checked her before breakfast and her glucose level was 80, then checked her at lunch and her glucose level was 120, I’d think she was having a perfect day, now I can see that after breakfast she actually went up into the mid 200s before dropping back down to an acceptable level before lunch. It’s great to know this additional information, because now we can try to do something about the post-breakfast spike. Yet with diabetes, even if you know there’s a problem, it’s not always easy to solve, partly because the insulin we give her from the outside is a much blunter instrument than a working pancreas.
It can be upsetting to know about every jagged peak and valley in glucose that her body is experiencing, and I think this disconnect between full knowledge of her glucose levels and full knowledge of how to fix them is why the CGM data sometimes feels like a burden rather than a helpful tool. Because it’s not that Mark, Bisi, and I lack the knowledge but could figure it out just by putting our minds to it (though there’s no doubt we could always be doing a better job). It’s that the scientific community—despite very helpful advances in technology like the CGM and the insulin pump—does not yet have the perfect answer to managing this disease.