Wednesday, October 17, 2007

I've thought over and over again about this post, and what I should say.
A brief rundown of the events since my last post. At Allison's suggestion and my desperation, I put in new sensor in on Sunday, the 7th. I was hoping to make each sensor last about a week or so, because I had 4 sensors and a month to use them. That sensor seemed to do alright for a day or so, but my blood sugars were also pretty decent. Wednesday, I restarted the sensor, and got another decent day out of it. On Thursday however, everything fell apart. I got a "cal error" at lunch. It showed me in the high 200s, when I knew I was just fine. I had been keeping a close eye on my blood sugar, to see if an ever challenging bagel breakfast bolus was working like it should. I had been consistently clocking in at 100 to 120. Maybe I should haven't have calibrated then, but I was frustrated at it's inaccuracy. Later that day, in a major national exam, the Guardian just went crazy. First, it told me a high glucose was predicted. Whatever, I felt fine, and I was in the middle of this very important exam. Not 15 minutes later, "Fall Rate." This is supposed to mean my blood sugar is falling more than 3mg/dL. Again, I ignored it again. Not 5 minutes later, "Rise Rate." By this point, I was ready to throw the thing out the window. I wasn't supposed to have any electronic devices in the room. I took my chances, and brought the Guardian. Then, I was forced to check it every 5 minutes because it kept alerting. When I got done with the exam (which I passed with flying colors, despite the annoying interruptions) I placed another annoying phone call to Minimed, who did not even want to help me, saying I should contact my doctors office. Finally, she told me I should re-calibrate when I was positive my blood sugars were perfectly level. I felt like telling her- look, I'm diabetic, if I knew when my blood sugars were going to be perfectly level, I wouldn't need technology like the Guardian! She said if I wanted to be completely sure it was back in line with my blood glucose, to restart the sensor. That's what I did. All Thursday night, it alarmed like crazy. First high alarms, then low alarms, all of which were disproved by a fingerstick. After a very frustrating, sleepless night, I tore the sensor out and put the receiver back in the box. I had enough. I kept it off all weekend, while I wrestled with what to do. My ideas ranged from putting it back on, to driving it back to the doctor's office 3 weeks early and telling them never to give it to anyone else. Calling Minimed for help is no longer an option. I've had three unhelpful conversations with them, most ending with them swearing their product is practically flawless, and I must be doing something wrong. Granted, they can't tell me what that is, but it is not their problem. They seem to have a mental barrier to the fact that I did not buy the unit, that I'm only borrowing it. Sorry for the tangent, back to reality.
Sunday, the 14th, I decided to give it another shot. I was going to make sure there was no reason for error. I put the sensor it 4 hours after lunch, with no additional food or insulin. Chances were, my blood sugars were not going far. I waited the 2 hour warm up period, still eating nothing, and taking no insulin. I waited another 45 minutes after the first calibration before I ate anything and took any insulin. I am only calibrating the recommended 2 times a day(I had been doing 3), first time in the morning, after fasting, and now in the evening, which I have also made a fasting time of day to prevent any possible errors. I hate that I am modifying my life to appease a piece of equipment that is supposed to help me. The accuracy has improved minimally. If I am between 80 and 150, it is very close, almost always within the 20% guideline. As soon and I drop out of that range however, the Guardian is way, way off. I realize that even fingersticks are more accurate with normal numbers, but I am talking about a difference of at least 100 points. It still has not caught an actual low. Most of the time, it showed me holding steady in the 80-90 range, while my blood sugar is in the 50's. I have decided to get over my disappointment and move on. The biggest reason I wanted to borrow the Guardian is to get my basals nailed down really well. To do that, my blood sugars should be within the 80 to 150 range anyway. I will continue to monitor my blood sugars like I normally would (not the 20 or so times I did for several days trying to figure out what the heck was going on with the Guardian) and give up on the dream that this equipment could help me prevent highs and lows. Someday maybe it will get there, but it has not arrived for me. Not yet anyway.


gary said...

Yes that does seem a bit disappointing, I guess you have tried a couple of different sites? My DEd said that it was break through tech, but prob really only should be used to gauge trends, I too was hoping it would identify Lo's and Hi's at least before they became extreme (at least that was the marketing hype), and hence could trigger me to take some action.

I would have thought it would be more accurate when your BG's were changing more slowly, but from what you did seems not? Do you think it copes better when you eat only high fibre / low GI foods versus sweeter / high GI foods?

It will still be a few weeks before I will be able to try the sensor out, but I hope to let you know whether or not it works well for me. Or perhaps if it works any better, what the differences may be?

I have had diabetes a long time now and like you was hoping this would be a good help - still I won't judge just yet. I know they are developing a sensor to read BG directly, but I guess that will be a ways off b4 it is released.

Let us know if you decide to try it again and how it goes.

Caro said...


Sorry you've had so much frustration with this. It certainly seems that while CGM systems work well for some, they don't work well in every person's body. I wish my experiences were more representative of the bigger picture.

I totally understand why you would want to give up on it, but I do have a couple of thoughts nonetheless - forgive me for giving you advice that I know you don't really want! I understand if you'd rather ignore me.

Firstly, if you got the sensors from your doctor's office rather than direct from Medtronic, can they vouch that they were properly stored? One of the only truly 'bad' sensors I've ever had was one that I had in my carry-on bag when I was stranded on a 32 hour flight delay in hot weather. I'm assuming the sensors are well in-date too?

Secondly, have you thought of trying different sites for the sensor? The abdomen doesn't work for everyone, particularly if you always infuse/inject there and may have some scar tissue. I started out always using sensors in my arms. If you still have a sensor left and you decide to give it a go, this may be worth a try. Hips, the top of the buttocks and thighs are all possibilities too.

A different angle of insertion may also help. A guy at Medtronic actually confirmed this tip. When using the Senserter, I tend to stand it up much closer to 90 degrees to my skin and see better results for it.

Also if you do still have a sensor left and feel like making a last ditch effort, you can always turn off all the alarms and alerts. This is a no-pressure way to give it another go. Alarms and alerts constantly going off are stressful and tend to make you obsess about and get frustrated with the results you are seeing. Without the alerts you can look at it when it suits you and take a more distanced view of the information it is giving you. Believe me, CG can still be very valuable even without the alarms.

Oh, and as far as calibration goes, I personally never give it a number that is more than about 20 points different. Even if it is screaming for a calibration. In this situation it is actually better to simply re-enter the last number the Guardian gave you. This will shut it up and means you continue to get data until you can resolve the problem. Feeding it a series of numbers that creep slowly towards the actual number will usually get it back on track - I call this "telling it what it wants to hear"!

Another way of checking calibration is to compare your finger stick value to the sensor ISIG. The ISIG value will normally be slightly higher than the value of your blood glucose in mmol/l. So dividing your finger stick value by 18 and adding a little bit should give you a number similar to the ISIG.

I am really sorry this hasn't turned out to be what you hoped, and I really hope you will have a positive CGM experience in the near future.

Jen said...

On the contrary Caro, I value any and all suggestions. I have the until until November 5, but I only have 1 sensor left. I try some of the things you suggested with my next sensor.
So far I've only done the sensors in my stomach, but I'm worried about doing them anywhere else. I do sites in my legs, and my absoprtion isn't as good there.
The sensors are in date, and I assume they have been properly stored. What would be the point of loaning it out if it doesn't do anyone any good?

Christine-Megan said...

I'm still pretty frustrated with mine. I'm not sure I want to keep bothering with it. I find it can tell when I'm dropping well- which is the main reason I wanted it- but isn't picking up highs at all. I'm also testing around 20x a day trying to figure out what the heck is going on.