For anyone that might stumble upon this blog while searching for DexCom or CGMS info, I thought I’d take a stab at explaining the mechanics of my new STS.
The STS consists of three pieces. First, there is the sensor, which is inserted into the abdomen using an insertion device. My first insertion was basically a pinch, nearly painless. The sensor is basically a plastic oval shaped disk that holds a very thin, short wire. Each sensor is FDA approved for three days of use, but I’ve heard from many folks that the three day limit can be exceeded (and DexCom is currently pursuing 7-day sensor approval).
Snapped on top of the sensor is the transmitter. This is one of the things that I liked better about the Dexcom (compared to the Paradigm). It’s an inch long black plastic piece with no wires. The parts that go on your body are relatively small and unobtrusive.
The third piece is the receiver. It’s an oval shaped unit, 2″ tall and 4″ wide. It comes with a case and belt clip so that you can keep it close. In order to receive blood sugar data, it must be within 5 feet of the transmitter. I’ve never comfortably worn my pump on a belt or clipped to my pants, so having the receiver attached to my waistband is taking some getting used to. The receiver has to be charged every 3 days or so. It can be charged while in use.
The unit has to be calibrated with a finger stick blood sugar every 12 hours. You can calibrate early and the 12 hour countdown gets re-set, however, which helps you avoid the need to calibrate at odd hours like 5AM.
Calibrating is a little cumbersome, requiring a specific meter (One Touch Ultra) and a cable. The unit seems ready made for manual entry of blood sugars, but apparently the FDA wasn’t too keen on that approach. Sticking to one meter (and a basic one at that) was necessary to keep the size and cost of the receiver down, according to my trainer. The cable fits nicely in the back pocket of the meter case, but that of course makes the meter case a little bulkier. Like anything with diabetes, I think it’s just a matter of getting into a habit (in this case, the habit of taking an extra minute twice a day to link the meter and receiver).
When you connect the receiver to a meter, it uploads all of your recent fingersticks and uses the most recent to calibrate. The advantage here is that when the unit is downloaded, you have all of your fingerstick and dexcom data in one place.
The receiver displays your most recent blood sugar and a graph that shows your blood sugar over the last hour (you can also view the last 3 and 9 hours). The graph has room for blood sugars from 40 to 400, and also displays a line indicating your low alarm threshhold (mine is set to 70) and your high alarm threshhold (I’m at 240). When your blood sugar… or rather the sensor’s take on your blood sugar… crosses that line, a beep sounds and a message displays. If you don’t acknowledge the message, the unit pesters you with sound and vibration until you do.
So that’s the run down on the DexCom STS. I’ll try to post some of my own pictures soon!