Sunday, April 17, 2016

Continuous Glucose Monitoring

In my last two posts, I referred to something called a "CGM." But since it's possible that there are other people even less tech-savvy than myself, I will try to explain it a little bit.

"CGM" stands for "Continuous Glucose Monitoring." It is a separate sensor inserted under your skin, similar to the infusion set inserted under your skin for the insulin pump to deliver insulin. But instead of delivering insulin under your skin, it collects data about what's happening to the glucose level in your interstitial fluid. Like insulin pump infusion sets, it is inserted into subcutaneous fat. Unlike insulin pump infusion sets, it is a small wire a bit longer than the infusion set tube.

This is a picture of the sensor after it's been inserted under your skin:

Continuous glucose monitor sensor after insertion
This picture is actually not only the sensor. The sensor is attached to the tape-y, clear blue-ish, purplish plastic part and lying under the skin. The gray piece (prominently adorned with brand name advertising) is called a transmitter. It organizes the information from the sensor wire, and sends it to a receiver.

Continuous glucose monitor receiver showing blood sugar information from the sensor
The receiver is what interprets your blood sugar for you. There's a few buttons on it that you can't see from the picture, but they aren't what's most interesting about the system. It's those little black dots that are so interesting! Together, they form something called a "trend graph." Every five minutes, a new dot pops up on the receiver, showing you what your most recent blood sugar is. I think the blood sugar reading is a few minutes behind, and you have to calibrate it so that the transmitter gives a proper number to account for the conditions it's sensing in your interstitial fluid. But check it out! A blood sugar reading of 116 requires a very different response when you are going up, going down, or staying the same, right? And have you ever wondered exactly what happened to your blood sugar in between meals? How, exactly, did you get to that 120 postprandial? And when you wake up high in the morning, was it a rebound from a low, or was it high for hours on end?

I got the Dexcom CGM back in December, and have been loving it. Medtronic also makes a CGM, but when I tried it a few years ago, it was so difficult to calibrate that I was never quite sure the reading it was giving me was an accurate one. I gave it up, and only took this one up again after Jenn and my friend Chris Hannemann said that the Dexcom system had improved upon the Medtronic one, especially in the manner of calibration.

The other wonderful perk of this machine is that it alerts me when my blood sugars are low and when they are getting high. Hypoglycemic incidents still happen, but sometimes I have been able to prevent them, and I have certainly had the chance to respond much sooner than I did before. Hyperglycemic incidents likewise still happen, but I am alerted to the rise in my blood sugars WELL before a 250 mg/dL 2-hour postprandial, so I can keep myself out of a high blood sugars for a little more of the time.

I know some people don't wake up when their hypoglycemic alert goes off in the middle of the night, but I don't tend to have that problem. However, if it doesn't wake me up, it will very likely wake my husband up. Between the two of us, we don't miss a single low. This has greatly improved my ability to avoid the scary lows I've had.

Do you use a CGM? What do you like or not like about it?

1 comment:

  1. Yes!! I am glad you are back and I love yhis site :) a CGM is a life-saver, especially dealing with pregnancy unpredictability :)