The Dexcom Knows


People ask me sometimes how I use my continuous glucose monitor (CGM), pump, and meter all together. I try to explain that it’s a fine titration– up a little, down a little. This is kind of what it’s like:

The bartender insisted it was diet Sprite. I asked, confirmed, asked again. Definitely diet. I was skeptical only because not a single restaurant or bar in Chicago thus far had a diet non-cola. I don’t trust my ability to taste the difference, but I figured the bartender knew what he was doing. As a hedge, I drank slowly.

Later on, nursing the drink, a friend came by, and offered to get me another drink. I thought he was asking what I was drinking (it was loud– really loud), and so responded with what I hoped was the truth: Diet Sprite. When he returned, he said the bartender he spoke to said there was no such option.

Uh-oh. I’ve been here before. I went back to the original bartender. “THIS IS DIET?” I asked, in caps so that he could hear me over the sound. He insisted it was. I tried to explain that this wasn’t just vanity or pickiness– I’m a diabetic! It was loud; I think the point was lost.

A discrepancy. I can’t tell the difference in taste, but a volunteer tester said it tasted sugary, but he wasn’t that great with the 7-Up-type drinks.

I ditched the drink regardless, and hoped that the fact that I had only gotten through a few ounces would save me from skyrocketing. Dexcom BG at the time was 88, and over the course of the discovery, had been starting to increase.

Uh-oh. I was expecting to be increasing slightly– was this a coming peak, or just a normal rise? BG meter said 90. So far so good.

I waited. Dexcom started jumping up. 94, 97, 105, with the arrow hitting 45 degrees and rising. BG meter said 93. Was the Dexcom falsely jumping?

Again, I hedged, and took 0.2 units of insulin. Dexcom jumps to 111, 124, rising faster and faster. BG meter says 108. I lean towards experience, and knowing that the Dexcom is probably a good leading indicator. 0.4 units in.

Dexcom next jumps to 146, arrows straight up, buzzing at me that it’s rising fast. BG meter at 124. Either the bartender was mistaken, or some other metabolic anomaly is hitting, but regardless, all systems a go! I bolus another 0.5, and make sure I’m walking. Dexcom hits 156, 166. I bolus another 0.2 during that time, hoping I’m not stacking, but also hoping I’m not under-estimating. BG meter reads 150, so I know Dexcom is still over-estimating slightly

And then Dexcom hit 170. Woo! That’s a promising sign! The decreasing rate of change implies I may be hitting nearing the peak. 170 again. Score. Topping out! 169. 165, 164. Uh-oh– a plateau? That’s dangerous. Sometimes a plateau is the lead-up to a phenomenal rise. BG meter says 144, so I hold. 161. Good sign. And then into the 150s, with a downward (45 degree) arrow.

At that point, I suspend my insulin pump, to avoid cratering on the other side. I continue to drop, quickly at first, then slowing as I near 100. Over the next hour, Dexcom shows me heading down into the 80 range. I correct, and eat 5g of carbohydrates, still with the pump suspended. I bottom out in the high 60s on the Dexcom, and then start heading back up. By the end of the night, I was hovering around the high 70s.

Crisis averted. Thanks, Bryan, for the tip about the drink! And thanks, Dexcom, for the indispensable window on the whole process, 5 minutes at a time.

And hopefully all the people I was talking to last night didn’t mind that a third of my attention was devoted to the calculation of the x-intercept of my blood glucose curve!

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Jennifer Jacobs
9 years ago

This perfectly captures the part of diabetes that few people without the disease (even healthcare providers) seem to truly understand: several sips of the wrong thing, and you’re distracted all night. I agree — thank goodness for the Dexcom — but it’s still exhausting and frustrating.

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