Freestyle Navigator CGM vs. Minimed CGM

Gina Capone Health Guide
  • Last week I got an email from my CDE:


    "I was wondering if you might be coming to the program at Health Trax on 2/26 (Note: Health Trax is a gym).  If you are, I wanted to ask you to be a guinea pig for me & wear a Freestyle Navigator while walking on treadmill & exercising during the program?"


    I responded a very quick "YES!" because I have heard such great things about the Freestyle Navigator and I am always up for trying something new. I am on the Minimed CGM as well, which covered (finally!) by my insurance company.


    She asked me to come in to the diabetes center two days before the testing to learn how to use the Navigator and to make sure I knew about any problems that can arise while wearing it. There was a representative from Abbott there to train me properly. She first explained the entire system to me and had a demo that was connected to a sponge that I practiced injecting into to see what it was like before I put it into my own body.

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    My first question was if I was able to wear my Minimed CGM simultaneously with the Navigator, or if it would interfere with the transmissions. (I didn't really want to take it off because it has been working really well.) But, she said that she has worn all three CGMs out on the market today at the same time. The Freestyle Navigator, Minimed CGM and Dexcom 7. (I haven't tried a Dexcom... yet!)


    I couldn't wait to get started to see the differences between my Minimed CGM and the Navigator.


    She took everything out of the packaging and at first it was very intimidating because the transmitter is pretty big and it needs a large serter to inject it.


    The Minimed transmitter is a little bigger than a quarter.


    She asked me where I would like to inject it and I know my CDE loves me to use my arms so I tried to impress her by using my left arm Smile. The CDE responded, "Girl Power!" which I thought was funny.


    The Rep asked if I wanted to do it or if she could so I let her since it really isn't often that you can get a diabetes break. She got the serter all ready and took the tape off and stuck it on my arm and pressed the button. I heard a loud POP. Done. The "pop" actually is the scariest part because I did not feel it at all. It did not hurt one bit.


    Here is front view of the Navigator



    Here is a side view to see how it sticks out.



    Here is the Minimed CGM




    This is my first comparison:

    Injecting sensors


    Freestyle Navigator: Little, to no pain.


    Minimed CGM: A lot of pain and bleeding after pulling out the needle almost every time. The best way to explain it is that it feels like you are getting shot. I have had to waste a bunch of sensors because there was so much bleeding.


    Setting up the Receiver


    Freestyle Navigator: The next part was setting up the receiver. It stores all of your data up to 60 days and it also gives you charts of what your glucose is doing.


    The Minimed CGM also has this feature.


    Freestyle Navigator: We progammed the receiver so that it would be able to tell if my blood sugar was going too high or too low. When it comes up, it shows under the number as projected low or projected high. I set mine to a low of 80 and a high of 180. This way it alarms me way before I am at the point of no return. It then shows up on the receiver as projected low or projected high. (I love this feature. It has helped me with 4 lows before they happened already.)


    The Minimed CGM does not have this feature.


    We then set up the alarms. Both Minimed and Freestyle have this feature.

    Directional Arrows


    There are four Tru Directional Trend arrows that show if you are steady, going too low or high at a fast rate, and then two more diagonal arrows that show if you are going up or down, but just not as fast.


    Minimed also has arrows but they are only down and up arrows. If you get double arrows in either direction, it means that your trends are moving quickly.


    Sensor life


    Navigator is approved for 5 days.

    Minimed is approved for 3 days.

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    Built in glucose meter


    The Freestyle Navigator is the only CGM system that currently has a built-in blood machine. (Awesome feature)




    Navigator: Takes up to 10 hours to calibrate.

    Minimed: 2-3 hours.


    The 10 hour calibration for the Navigator came at 3:30 am that same day. It started giving me readings right away. The Minimed CGM does that as well.


    What I did not expect were the meter and the CGM to be almost identical after the first glucose calibration. I was amazed. Usually my Minimed CGM is not as accurate until the second or third day. And then you get Sensor End. It can be very frustrating.


    The next morning it started beeping to tell me about a projected low. I was so grateful because it was alarming me so much earlier than the Minimed. The Minimed didn't start alarming until about 15-20 minutes later and I was already sipping on juice. I continued my daily routine throughout the rest of the day. After I ate, I tested out the line graph tool on the navigator and compared it to the Minimed.


    The Navigator told me I was at 124 and the Minimed said 202. So I checked my blood on a finger stick, and it was 120. Wow! What accuracy, huh? The rest of that day went pretty much like that... where the Navigator was right on and the Minimed lagged.


    That night I went to the gym and I have to say I felt so much better going that particular night because I had reassurance by not one, but two CGMs. I was not scared of going low and my mind felt a lot clearer. I did my normal workout routine by starting off with cardio followed by some resistance training. Halfway through, the Navigator showed an down arrow to let me know my blood sugar was dropping very quickly. I checked my blood sugar and I was at 89. Eighty-nine is not a bad number to be at, but because I had the CGM beeping with a down arrow I had to act fast or else I would be low in no time. I started sipping some juice that I always carry with me, stopped for a bit, and continued to do my strength training.


    The Minimed did not display any arrows and was telling me that I was at 196.


    Wednesday came and I woke up to find that both the Navigator and Minimed were finally in sync with each other the whole day and pretty close to the numbers on my blood meter as well. It took the Minimed two days to catch up. (I was wearing the Minimed for a total of 6 days when it finally caught up. I noticed the more days you wear the same sensor, the better the readings.) The Navigator was pretty accurate right after the 10 hour calibration.


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    Thursday night I had to go to the Health Trax Gym to meet my CDE for the Navigator exercise program. They had me go on the treadmill and let me put it at the pace I would normally do at my own gym.


    Again, there was a representative from Abbott present who had a video camera set up, which went to a screen on the wall to show the rest of the people with diabetes what would happen during my exercise. (While I was on the treadmill the rest of the people were going to be learning about how to use their pumps with exercise. None were on a CGM.) I hopped on the treadmill and I started a warmup for 5 minutes at a pace of 2.5, then I gradually moved up the speed and the incline as I would any other gym day.


    My blood sugar started at 192 on the CGM and on a finger stick it was 199. After 5 minutes, the Navigator showed that my blood sugar went down to 188. After 10 minutes it was at 177. In fifteen minutes it was at 166 and at 17 minutes I started shaking and then the CGM started beeping a projected low glucose with an arrow going straight down. The number on my CGM said 133. A couple of minutes later the Minimed also started giving me two arrows down as well.


    I got off the machine to make sure I was OK, and the number on the screen turned to 123, still with projected low glucose and a downward facing arrow. I checked my finger and I was at 120. Again, if I did not have this technology I would not have stopped with a blood sugar of 120. I could have been in real danger if I didn't feel the low symptoms coming on, either. My sugar was dropping at a very quick pace in a very short amount of time.


    The Navigator gave me a projected low way before the Minimed caught up - it knew my sugar was dropping quickly. A lot of times while I am wearing the Minimed, it starts beeping when I am at the programmed 95. So by the time I check my finger to make sure, I've already bottomed out.


    Another good thing about the Navigator that I wanted to mention is that the alarm is much louder than the Minimed when I am low. On Tuesday morning it woke me up with a projected low alarm and I actually woke up. With the Minimed, I could hardly hear a thing while I am sleeping and I keep the pump up high near my pillow (not under it) when I sleep. You also can't hear it under the covers, either. 


    My CDE is letting me wear the Freestyle Navigator until March 8th, and so far I love it except that it is huge! But, as long as it works ... who cares, right?


    So keep checking back to see how well or not the Navigator is working for me.


    Do any of you wear a Navigator or Minimed CGM or are thinking of switching? I am curious to know how you like it; share your thoughts below!














Published On: March 02, 2009