Insulin Pumpers: Learn from My Experience

For those of you who don’t use an insulin pump[1] and who are not familiar with the nuances of pumping insulin, some of the content of this week’s blog entry may either be cryptic or irrelevant, or both. My hope is that a nonpumping and unfamiliar-with-insulin-pump audience will be able to get the gist, however. So, without further ado…

Beware the infusion site that appears to be happily stuck to your skin following a bump or tug or some other outside impact on said site. For all outward appearances, it may seem perfectly fine. But heed my experience for the cannula tweak.

Confused? Okay, here’s what happened. Sunday for dinner we had a delicious angel hair pasta with tomatoes and basil and Feta cheese. I bolused for the meal, ensuring that I had more than enough insulin[2] to cover the carbs in a meal such as this. We’re talking a 7 PM dinner, and so by the time I checked again two hours later, I was somewhat surprised to find that my blood glucose was high.

However, because after two hours I still had insulin on board (I have a three-hour duration-of-insulin action), I didn’t issue a correction bolus for a blood glucose in the low 200s.

I decided to check my blood glucose again before I went to bed at 11 PM, and this time it was in the low 300s. What the heck? I examined my insulin pump to ensure that the bolus for dinner had been completed (it had); I looked at the tubing to make sure nothing was wrong (it wasn’t); and I looked closely at the infusion site on my stomach to verify that the site itself was in place and nothing looked amiss (nothing looked amiss).

So what was going on?

I figured that perhaps I had bolused erroneously; there were a lot of cherry tomatoes in the meal, and maybe I didn’t pay enough attention to their carbs. But to be more than 200 mg/dl above my target blood glucose level? Something wasn’t right.

I issued a correction bolus and decided I would stay up a few more hours and check at 1 AM. (I had no difficulty remaining awake because I was addicted to watching pundits talk about the presidential election.) At 1 AM, I checked again. Still in the 300s. Unphased by the high numbers, or rather, not panicking because things like this no longer cause me too much grief, I decided to do a complete change of insulin-pump supplies: new insulin, new reservoir, new surgical tubing—new infusion site, in short.

When I removed the old infusion site from my stomach and examined it, I noticed that the cannula was bent and lying flat against the hard plastic backing of the site. And on my stomach I noticed an irritated few-millimeter valley indention where the cannula had been lying flat and pushing against my skin. There had been no subcutaneous cannula since around noon on Sunday!

And why was that? How had the cannula become dislodged without the infusion site adhesive coming undone?

I’m pretty sure that what had happened was that at noon, when I was carrying my laptop upstairs, I dislodged the cannula inadvertently. Let it be known that I’d been doing yard work not 30 minutes earlier, so I didn’t have my insulin pump attached (the site was there, but it wasn’t “completed” by the tubing’s attachment, which rounds off and smoothes out the site; when the surgical tubing isn’t attached, the nub upon which the tubing attaches protrudes and has a greater chance of catching on something).

I guess that I “popped” the cannula out when the laptop grabbed the infusion site momentarily as I shifted it from one hip to the other. I felt the laptop catch on the site, but when I checked to see if the adhesive had become unstuck and found that it hadn’t, I thought that everything was just fine.

Instead, what had happened was that the center of the site rose quickly, imperceptibly to me, and with it the cannula. However, the cannula didn’t drop back into my body; instead, it buckled and folded under the site. For the remainder of the day, through basal and bolus, the insulin pooled under the site and was never administered into my body.

The mystery of the high blood glucose numbers had been solved.

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Eric Lagergren: Eric Lagergren was born in 1974 but didn’t give much thought to diabetes until March 2007, when he was diagnosed with Type 1. He now gives quite a bit of thought to the condition, and to help him better understand his life as a person with diabetes, he writes about it. Eric is the senior editor for the Testing Division at the University of Michigan’s English Language Institute in Ann Arbor. (Eric Lagergren is not a medical professional.)

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