Lessons learned and sunny skies ahead?
I also need to introduce you to our new friend SG. SG is Sensor Glucose and is a close cousin of our best friend BG, or Blood Glucose. SG is what the Guardian reads, basically sugar in the interstial fluid. The movements of the two values are closely related, but not exactly the same. Blood supplies sugar to the fluid which in turn feeds the cells. It is apparently possible for BG to be going up and SG to be going down or visa-versa at the same time. Don't panic. It is all part of the same system. It is like measuring water temperature. Do you stick the thermometer into the stream below the faucet or at the drain? We are used to thinking about measuring from the faucet. In the future I'm convinced that all diabetes control will be interstitially based. For the sake of our mental sanity, however, the Guardian monitor feeds us data translated into BG numbers.
The troubles with Sensor number 7 were, I'm tickled to report, my own damn fault. My words, not theirs. They are waaaaay to polite for that kind of language. Actually, by the time they called I was beginning to suspect the truth from my own study of the data, but it was nice to have it confirmed by people who know what they are doing.
Before I tell you how stupid I was I want to tell you what I found out about bad sensors. A bad sensor can happen. There are basically two types of failures. In the first there is a physical problem with the sensor, and this kind will be quickly detected by the system. The transmitter passes a current though the sensor to check on it. This testing happens throughout the sensor’s
life. If there is an electrical problem with the senor, the Guardian will let you know and tell you to replace it. The other type is a sensor that has not been put into the body correctly. This leads to an erratic "tracing." Your SG track would be a dotted line, not nice and solid. By the way, they loved my traces. All were good and solid, and the accuracy was top notch up until number seven. They weren't surprised that I got shook up, given how the first six looked. They asked how it had been since. (We've had number eight come and go and I'm now on number nine. Deb and I sat down last night and studied the charts carefully and decided that eight started off a bit rocky but settled in and a that for the rest of its stint of duty it compared well to the fist six. Also, number nine is tracing well and with the same flow as the finger sticks.)
In a nut shell the problems had to do with calibration. When it comes to entering finger sticks into the Guardian more IS better, BUT only when things are relatively stable.
By the way, the official line now is: 5 or 6 calibration sticks on the first day of a sensor, and four sticks each on the second and third days. But, but, but! Never ever, ever, ever when BG is shooting up or down. The recipe is about 15 minutes before meals (unless you haven't eaten for 12 hours and your BG is falling like a bungee jumper).
Sensor number seven was ultimately the victim of Panicky Diabetic Syndrome. I got so freaked out with it's performance that I fed it a boat-load of finger sticks. This was on a bad BG day with my sugars rocketing upwards and downwards. I was feeding it data on a slippery slope. The sugar is this. No, the sugar is that. No, wait, the sugar is the third thing. The poor little thing tried to keep up, but...
Basically I gave it a nervous breakdown.
So when you get a guardian alarm it is important to take a finger stick to confirm what is going on, but don't ever enter the damn thing in as a calibration point. That is what I’ve been doing wrong. I entered EVERY finger stick I took into the unit. I thought I was supposed to. I thought that made it more accurate. Well, yes and no. If you feed it a boat load of calibrations in calm waters, then yes, it can help. But on the wild open sea in a typhoon of blood sugar, that is another story all together.
In my defense, the manual is a little sketchy on this point and I gently suggested to the folks at Medtronic that a longer discussion of it would be in order with the next generation....
From the manual: “A fingerstick glucose reading should be entered every 6 hours, however, a minimum of one meter reading must be entered every 12 hours. More frequent daily readings will optimize the accuracy of the sensor glucose readings.” That’s about all that was ever said. The manual needs work. They should really hire me to re-write it. Wow. I just had a scary mental image of myself dressed in rags on a street corner holding a sign: Will write for sensors.
I anyway, so I had thought that the more the merrier. I told all of you the more the merrier. But that is not the case. The new PLAN:
For the second and third days I’m thinking something along the line of:
Calibrate as soon as I open my eyes in the AM.
Calibrate 15 minutes before lunch.
Calibrate late afternoon. Maybe 5:30ish. We eat dinner anytime between 6 and 8pm. I don’t want to wait too close to dinner because often I’m droppppppppppping!
Calibrate at bed time.
That gives me my four sticks at my most stable times. By the way, I asked if they thought forearm tests would be better for calibration as they are less prone to show quick shifts, but no one knew if that was a good idea or not. Guess I’ll stick with the finger tips for now.
Of course, I’ll still do my post meal sticks, but I won’t enter them into the girl.
I’m still kicking around how to handle the new sensor. Skip break fast on insertion day and eat a brunch instead after the new sensor is calibrated? How on earth to fit six in on such a day? Maybe four hours after lunch, then late afternoon. I’m up to three and it is dinner time.
Hmmmm.... seems a little hopeless, but I’ll come up with something.
So, in the end, after our first fight the girl and I have made up; and are once again (for now at least) the best of friends.