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The CGM Analysis: Week One

December 15, 2008

Life has been a bit chaotic around my neck of the woods the past few days, so I’ve been deliquent in posting my initial CGM analysis.

Last Wednesday, Jaimie, a sweet fellow Hobokonite and Minimed trainer, came over to my apartment to show me how to use the Minimed Paradigm CGM. After seeing so many pictures, hearing so many anecdotes and actually using the DexCom, hooking myself up to the CGM wasn’t all that scary or complicated. I think the most troubling part of the whole experience was having to use an serter for the sensor. I use the silhouette sets for my insulin pump and I put them in by hand. I’m a control freak. However, Jaimie told me that because of the thickness of the needles and the depth at which it needs to go, it would be extremely painful to do it by hand.

After the instruction on how to load the serter, I put in my first sensor. Despite my extreme apprehension at having a needle that big shoot through my abdomen at high speeds, it didn’t hurt at all. I barely felt it, actually. I also had minimal bleeding, which Jaimie says it’s actually fairly normal. Only when you have a lot of blood, or it starts to drip and won’t stop (ewwww!) does that mean there is a problem.

I geared up the transmitter and waited patiently for it to tell me I could enter in my first calibration reading from my glucose meter. Unfortunately, I happened to lose signal part way through the 2 hour wait period, so I ended up not calibrating my sensor until after midnight. On a school night. It was horrible. My blood sugars were also frightfully high so the CGM also alarmed about once an hour throughout the night (I ended up having a bad set and didn’t recover until mid-afternoon the next day – but I digress…).

So far, the CGM has been okay.

Not good, not spectacular. But not miserable or a waste of time.

As stated by countless others, the CGM works well for trending and patterns. Not so much for the actual number.

Problem? You can’t actually set the CGM to alarm with trends, only for when you hit an actual number. So you could be dropping sharply or rising dramatically, but you won’t know anything until your CGM says you’ve hit that Magic Number. But you could already have been well above or below that Magic Number by the time your sensor picks up on it. It’s very frustrating.

I’ve taken to checking the CGM about every fifteen to twenty minutes, just to see where the arrows are pointing. It has encouraged me to test my blood sugar when I wouldn’t normally think to. On Saturday night, I had a wonderful dinner at an Indian restaurant in the East Village and then went off to see Nothing Like the Holidays. When I went into the theater, my blood sugar was great. When I left the theater, the CGM told me that I was going up dramatically. I felt fine, but because I had such a big meal and I was going up so quickly, I should test my blood sugar. I was 303 mg/dl, I immediately corrected it and was done within an hour. If I didn’t have the CGM, I probably wouldn’t have tested again until I got home, about an hour later.

The CGM, however, has not been so good with catching the low blood sugars. The CGM, I’ve noticed, trends towards normal. That is, when I’m high, it reads low, and when I’m low, it reads high. The arrows are spot on. Yesterday, I hit a knee-buckling 42 mg/dl, and while my CGM said I was 106 mg/dl, it also had 2 arrows and told me I had dropped 40 points in about 20 points. Again, it would be great if my CGM could alarm when I had those arrows instead of relying on chance that I would look at the screen to see where I am and catch the low or high in progress. Seems logical to me… Anyone from Minimed reading this?

That said, I have only been on the CGM for not even six full days. I’ve used exactly one sensor. I know that different sensors can work differently and that different places on your skin can work differently. I am blessed with a health insurance company that believes in the power the CGM (or at least is wise enough to not deny the option) and I have a three-to-six month supply of sensors sitting on a shelf in my kitchen. My next A1C test is in late March. If my A1C comes down even half a percent, I believe that this will be worth it. Any assistance or insight into this complicated and frustrating disease is eagerly welcomed.

  1. Randee permalink
    December 15, 2008 6:27 PM

    I’ve been using the CGM (minimed) for the last couple of months & I agree with the frustration about the numbers being off. For me, the biggest benefit is when it catches lows that I don’t feel at all. It doesn’t catch them all every time, but it has caught a few where I would not have noticed otherwise. For me, that added safety is enough to keep me wearing it, even though it comes with plenty of irritation as well!

  2. December 15, 2008 9:38 PM

    I just started my first CGM from Minimed last Thursday so I’m in the same place you are. I also use Silhouette infusion sets and like the control I get from them so I was hesitant about the inserter, but it didn’t hurt me either.

    I’m trying to use mine to catch highs and I’ve set it to 130. Ironically it *just* went off (I over-corrected a low about an hour ago) and the real number was 170. I can’t imagine what it would be like if I waited for it to get to 170 on the CGM.

    My complaint is the alarms are not nearly loud enough to wake me up in the middle of the night but I’m a really heavy sleeper. I’ve got to try putting the pump under my pillow or something.

    Hope it continues to go well for you! I’m still optimistic about it and it’s definitely better than nothing.

  3. December 15, 2008 10:11 PM

    I love my CGMS. It has, on at least one occasion, saved my life, catching a low. It beeped at 80 (it was the middle of the night). I woke up and tested at 38. Sure, it didn’t catch it quick enough, but it caught it when I am not sure that I would have caught it on my own. So I can’t complain to much. I do agree that it should have some sort of beep for the arrows. We should talk to MiniMed! Maybe the next version….
    It also helps me out with the highs. I have my magic number set at 200. Usually by the time it beeps I am already in the mid 200’s when I test, but I think I wouldn’t have caught it until much later without the CGMS.
    Oh, the beeps aren’t loud enough in the night either, but it starts vibrating after about 20 minutes I think (maybe sooner, I’m not sure) and I am usually laying on the pump or it is hooked to my pajama bottoms, so I feel it.

  4. December 16, 2008 2:32 PM

    The good news is that the Guardian Real Time – the one without the built in insulin pump – does have alarms for the trend arrows. I would think it’s pretty likely that this feature will be incorporated into the next in-pump version. I certainly hope so anyway!

    I do find the trend arrows slightly frustrating though in that they work purely on paired values. So a trend arrow only shows when there is a significant difference between the current reading and the one 20 minutes previously. It is possible to get an upward trend arrow when your most recent reading is actually lower than the last one and vice versa – for example when you reach the height of a post prandial peak. It’s not a major problem, but it does irk me!

    I still believe that the “testing when you normally wouldn’t” is one of the major, and often understated, benefits of CGM. I often tell others who are new to CGM to think of it both as something to help pick up trends, which is the commonly discussed benefit, but also as something to prompt you when to test your blood sugar for best effect. Without CGM, the times we select to test are often nothing short of random, especially for those with hypoglycaemia unawareness.

    Glad it is going ok though. With more time you will fine tune the way you use CGM, just as we all had to fine tune the way we use our pumps.

  5. December 17, 2008 12:52 PM

    Thank you for sharing. I am still in the process of trying to get a CGM approved by my insurance, but it’s nice to have an idea of what to expect! I think even having the benefit of the trends and patterns sounds great! It would help me know when and where to adjust my basal settings much more effectively! To bad it’s not more accurate though. I hope they will perfect it and eventually it will be easier to use and more accurate!!

  6. December 17, 2008 1:48 PM

    I almost threw up when the educator told me that I had to use the inserter. I don’t know why pressing that button is soooo much worse than sliding the silouhette in manually, but it is, by powers of 10.

    Then my first sensor went rogue on me after being in for about 8 hours.

    Now? I like being able to look over and see where I’m headed or where I’ve been. I feel like I understand better how I’m absorbing food and matching insulin to the food. My Minimed are you listening moment – PLEASE PLEASE PLEASE come up with something so that I don’t have to manually enter all my blood sugars.

  7. December 17, 2008 3:57 PM

    Art-Sweet: I TOTALLY forgot about that whole “You can use the radio-frequency when you’re on the CGM.” Who the H-E-double hockey sticks came up with that? You create a piece of technology that has the power to transform how we take care of our diabetes and you can’t turn off the auto-update feature? I mean, WTF? O.M.G.

  8. December 22, 2008 1:17 PM

    Hi Allison!
    I got the link to your blog through your tudiabetes page and think it’s pretty great. I just started my CGM last week too and fortunately, it’s been mostly good so far. I’m sorry that the minimed hasn’t been more productive for you yet. Anyways, I wish you luck with your optimization process. If you figure out any tricks, please post them! Looking forward to reading more in the future.

  9. Jim permalink
    July 23, 2009 12:19 PM

    I’ve been wearing the Minimed CGM for a month. I had to fight the insurance company for a year to get one. Hate to say it but Blue Cross was right. The readings are so far off from blood glucose readings. The only thing it is good for is to spot trends, but your own body tells you you’re going low or goting high already. Was a the gym the other day, trend arrow down, CGM said 138—felt weak. Blood sugar was 48. I’d rather really on my own read from my own body than the CGM. Gonna give it another month. If it doesnt get better, I’m going to give up on it.

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