I don’t want this post to sound negative, as I’m quite liking the modus operandi of the FreeStyle Navigator.  But as you can see, reader June S. hit the nail on the head when she said, “Yikes! How can you fit a large ‘Pod’ on your body PLUS the large Navigator transmitter/receiver?” Two lumps are a lot of gear on your skin, especially in the sizzling summer heat.

After wearing this double-duty almost all week, I have some additional observations to share.

First, did I mention that the Navigator has a 10-hour warm up period?  That means once you insert the Transmitter, you have to wait 10 full hours until you can fire up the Receiver and get monitoring.  This kind of shocked me at first — until I remembered that the DexCom folks had actually suggested doing the same. It’s not officially in their product literature, but the rep did suggest that the sensor needs time to “settle in,” so one ought to insert it the night before and “sleep on it” before activating the session. A number of articles remind me that “all the sensors presently on the market need a number of hours to settle in to the body before they can start giving accurate glucose information.”

Hmmm.  This interstitial fluid method has its drawbacks, no?

There’s also that lag time issue, which can create a lot of frustration.  I noticed most of my hypos before the alarm ever went off, for one thing.

In fact, had some internal strife about setting my BG alarm targets here.  My inner perfectionist insisted that “targets” should always be very tight, like the 90-120 set on my pump.  But the Abbott rep reminded me that CGM “targets” are really only for alarms, and record-keeping, i.e. to illustrate when you are in the “zone,” that shaded stripe on the graphs in which your BG is happily within range.  The key is deciding when you want your alarms to go off: at 70? or 60?  At 200? or 180?  Too much alarm action can drive you nuts.  I also had to remind myself that tight BG targets on the pump are necessary because you want that device to calculate insulin corrections based on getting you back under 120 asap.

Low Troubles

I must report that I had the same overnight issue with Navigator that I’ve had with other CGMs: I usually run in the high 70’s or low 80’s while sleeping, and the darn thing just won’t stop beeping me awake all night trying to alert me to a hypo I’m not having.  I set my low alarm to 65, and for some reason the CGM keeps reading me there, even when I’m not.  But I don’t want to raise my hypo alarm either, as I sure as heck need to be alerted of impending lows during the day.  So like its predecessors, the Navigator ended up in the hall laundry basket a few nights this week. Aaargh.

High Troubles

Please don’t balk, but I set my high alarm for 200.  Because if I set it any lower, it beeps like crazy after every meal — which is unbelievably aggravating when you’re trying to conduct conference calls, watch a movie, or shop without creating a scene (all the little things collectively known as having a life).  But if don’t set the “hyper” alarm to a lower level, I miss some 170s and 180s throughout the day.  This is an ongoing dilemma for me with CGM, I find.

Skin Troubles

Finally, I must admit I had to abort my first Navigator mission a day early.  That adhesive started bothering me on Day 2, and in this incredible heat wave we’re having, the spot turned into a full-blown hive by Thursday morning.  Actually, the adhesive peeled up on Wednesday, so I smacked an extra Smith & Nephew adhesive patch over it (provided in the Navigator start-up kit). But this got bunchy and created a pool of trapped water after my first shower, that served only to turn the hive into a welt.  Yipes!  My poor belly has been through a lot in this heat.

I’m aiming for my arm next, so can I dig down into the features of this nice, clear new system — which I’m convinced I would love best if only the lump were smaller.

Friday, July 11th, 2008 | Permalink | Comments (10)