[Subby]

I'm getting a few days use of a mm CGMS in a day, the type that integrates with my paradigm. I buy a sensor ($80 AU) and borrow the CGMS, the DE will get it up and running for me.

Having only been on CGMS once before, and an older system, I am an absolute newbie with this. A couple of questions to the CGMS pros:

- is it true I might be able to stretch the sensor to 4 or 5 days, of am I getting that mixed up with something else?

- Any hints or tips you think I really should know?

Thanks.

[Ray4Rick]

I've been on pump with CGM for a month now. I change my sensor every 6 days. But many folks on here have used the same one for 10-12 days. I'm trying to last as long as I can with the one I'm using now.

If the weather is hot, keep the sensors in the fridge. I had many problems last week, went through 4 sensors in a weekend because I was getting weak signals or loss signals. Again folks on here told me to keep them in the fridge and so I did. I'll see next change if I have an easier time.

Good luck to you mate,

[JediSkipdogg]

I'm not sure the max time on a Minimed sensor but I'm on day 16 with my Dexcom sensor.

As for the temperature, I believe that 76-80 degrees is the max a sensor is allowed to get before being inserted. Not sure once inserted if there's a max. I've been leary of using a hot tub since starting because I'm not sure what that extra heat would do.

[Coppernob]

Subby, I am on the minimed system - 522 with CGM. I keep my sensor in for a week because it really suits me to change it on the same day every week. For the majority of the time, this works really well and the sensor could last a bit longer if needed. However, sometimes it starts to act up in the last 24 hours and the readings start bouncing all over the place, not coming close to a metered BG. I am very happy with the way this system works for me.

The only other thing I would say is that you have to try different locations in placing the sensor to decide what works best for you. Each of us has to find the place that gives the best readings without discomfort. For me that happens to be the outer part of my thighs - I just alternate legs each week. Other people prefer buttocks, abdomen etc.

Good luck Subby - hope it all goes well.

[poodlebone]

Originally Posted by Subby

I'm getting a few days use of a mm CGMS in a day, the type that integrates with my paradigm. I buy a sensor ($80 AU) and borrow the CGMS, the DE will get it up and running for me.

Having only been on CGMS once before, and an older system, I am an absolute newbie with this. A couple of questions to the CGMS pros:

- is it true I might be able to stretch the sensor to 4 or 5 days, of am I getting that mixed up with something else?

- Any hints or tips you think I really should know?

Thanks.

Yikes! Is that AU$80 for just one sensor?! Here in the USA they're US$35 each if you buy a box of 10 and only very slightly more expensive per sensor if you buy a box of 4.

Yes, you can usually extend the life of a sensor well past three days. When you insert a sensor, Minimed says to wait X minutes (5? 15? Don't remember the actual number...) before attaching the transmitter. My CDE told me to wait at least 20 minutes. The longer the sensor sits and gets "wet", the better. The transmitter has a built-in 7 day timer and that starts as soon as you attach it to a sensor. The sensor has a 3 day cycle that starts counting down as soon as you do the first calibration. At the end of 72 hours, the pump will give a Sensor End alarm. You just go back into the Sensor menu and choose Start New Sensor. You don't have to turn it off first, you don't have to touch the sensor or transmitter. Just choose the Start New Sensor option. Within 5 minutes (usually less), it will ask for a calibration and you can start a 3 day cycle all over again. After another 72 hours, you'll get the Sensor End message again. You can restart it another time (Start New Sensor) but the following day you'll start to get Weak Signal messages, which means the transmitter needs to be recharged. You can carefully peel up the dressing (keep a finger pressed firmly on the plastic sensor hub to prevent it from pulling up), remove the transmitter and recharge it. Then reattach, tape it all down and wait for the 2 hour warmup period to calibrate. If you do remove/recharge the transmitter after 7 days, you can reattach it to the sensor as soon as it's charged. The sensor will already be good & wet since it's been in for a week.

Calibrations: Make sure your BG isn't moving much when you do them. Don't do it too soon after a bolus, eating food or exercise. When you do the very first calibration, the next one is due within 6 hours. You don't have to wait 6 hours and can do it earlier, when it's convenient for you. After that you'll need to calibrate every 12 hours but you can do it more often. I wouldn't do more than 3-4 calibrations per 24 hours, though. Just do them so the timing works out for you. You don't want to get a message asking for a calibration at 2:00am!

Taping: Keeping the sensor taped down so it doesn't move is important. When I insert a sensor I put a strip of tape (paper tape or some plastic-y cloth tape I have) over the plastic sensor hub, making sure I don't cover the two little prongs that snap into the transmitter. That keeps it stable while I'm waiting to attach the transmitter. When the transmitter is attached I usually use Opsite Flexifix to cover the whole thing. Since you're not going to beusing the CGMS full time, just use whatever you have as long as it will keep it all covered & stable. The transmitter/sensor connection is waterproof but if you do keep getting it wet the little adhesive will loosen and the whole thing can come out. So, better to keep it all covered up.

ISIG: The isig is the raw data the pump uses to calculate your interstitial glucose. As your BG goes up, so will the isig. As your BG falls, so will the isig. In order to calibrate your calibration factor should be between 2 - 20. To get the factor, divide your meter BG by the isig and it should be between 2 - 20. Of course, that's in mg/dl so you'll have to do the math to translate from mmol/l! When you first attach the transmitter and turn the system on, it will go through a 2 hour warmup period before asking for the first calibration. If you look at the sensor status screen you'll see the isig number changing a lot, going very high and very low and everything in between. That's normal and it will settle down. When a sensor is dying the isig will usually drop lower & lower. Eventually you'll get calibration errors because the isig is too low, and you'll see your sensor readings flatline at a low number.

Sometimes the MM sensors need extra time to get wet and the readings you get may not match your meter readings well. It can be frustrating, but they usually will pick up. I've had sensors that were not very good at all for a day or even two, then sudden;y fell in line and worked great. If you find that the readings don't match well fromm the start, just give it time. I will sometimes just turn the sensor off (in the pump menu) and leave it alone for several hours or overnight. When I restart it, the isig is almost always higher and the readings will track much better.

I've lost track of when I put my current sensor in. I've already recharged the transmitter once. I'm on either day 11 or 12 now and it's been working great. My record is 17 days, and that was in the same area as my current one (upper thigh, right near the top). Some have lasted only 5 days. Most average around 9-10 days.

[Subby]

Awesome replies, thanks a lot. As well as useful now, I have this info bookmarked for if I get a longer run with the CGMS. I am getting it on my Tuesday, it seems they usually run just for 3 days per "borrow". I will see if I can hedge to keep it over the weekend, make some excuse about hard to get it back Friday if need be... and try and extend the new sensor trick. I'm sure going to try that considering the cost...

Liz, yes, that's the price here for one sensor, as CGMS has not reached being covered by insurance in any shape or form yet. Obviously, fingers crossed it does soon. The accounts of how long the sensors can last make them even more tantalizing to think of them being affordable. For now, this is about the most exposure I'm going to get in the meantime...

As for the sites, considering I've only got one shot at this, am I best to go for a site I know works with the pump, or are the rules different? For example, while I occlude at many other sites, my upper butt is my all time best pump/injection site, should I just go for that?

[poodlebone]

A lot of people do use the upper butt. Just make sure that the sensor isn't inserted near an infusion set. Also remember that the pump has to be able to communicate with the transmitter so it needs to be worn fairly close to where you've inserted the sensor.

Are you sure that the transmitter they're letting you borrow will communicate with the pump? Minimed makes another system called the iPro (I think) that is used in doctor's offices and clinics. When patients wear that, they don't see the readings until the transmitter is returned to the doctor and they download it. I believe the sensors are exactly the same but the transmitter must be different somehow. The patient doesn't have to worry about doing any daily calibrations.

[Subby]

OK, butt it will be, away from set. My DE did suggest that my pump would display the results as per the paradigm "real time" system, but I guess I won't know for sure until my appointment.

[GretchO]

Subby...poodlebone has given you a great overview. I'd also add that MM suggests a 45 degree insertion angle...I'd go a bit steeper (closer to 60 degrees). I've had my current sensor in for 7 days so if you can finagle a few extra days I'd go for it.

[Coppernob]

Originally Posted by Subby

As for the sites, considering I've only got one shot at this, am I best to go for a site I know works with the pump, or are the rules different? For example, while I occlude at many other sites, my upper butt is my all time best pump/injection site, should I just go for that?

Sorry Subby, I got so carried away with the idea of your getting a CGMS that I forgot it was a one shot deal! Hopefully it won't be too long before you have your own system.

Poodlebone's info is really good and I agree with Gretcho's comment about the angle - in fact the diabetes educator who started me out with the sensor said the same thing: insert at an angle of at least 60 degrees.

Good luck, Subby, hope it all goes well for you.

[Subby]

Hey no problem, and thanks for all the advice, it's all good.

You know, hearing that the sensor can last for quite a bit longer... means I am going to be thinking very carefully about seeing if I might buy a system and use it on an occasional, but consistent basis. I am by no means rich at all, but may have recourse to funding this... I am at a stage where the better I get my BG, the better the rest of my life is going to be, and if it helps me do things like go well at uni/hold down work (and any help with stability will definitely help with that)... Others might buy a new car... perhaps a CGMS will be my preference while I drive my old bomb around. We shall see how it goes. I have no doubt that the CGMS would not be worth a lot of money to some, but I really have had reactive BGs for years to those frustrating factors like stress, no matter what I seem to do, maybe it's worth some sacrifice to gain persistent insight into what is going on. Thanks for your enthusiasm - I share it!

[poodlebone]

Originally Posted by Subby

OK, butt it will be, away from set. My DE did suggest that my pump would display the results as per the paradigm "real time" system, but I guess I won't know for sure until my appointment.

One thing about a butt site. If you don't have anyone to help you, it could be difficult. Unlike an infusion set which only has that little built-in adhesive to worry about, the whole sensor/transmitter must be taped down securely. Also, it can be tricky to attach the transmitter if the sensor is in an awkward place.

[Subby]

OK, well I've been running with it tracking for about 4 or so hours now. I was/am impressed at the size, and the on screen display. It has not been overly accurate yet. I had two mild hypos that it has just completely missed. (3.5 mmol/l each time = cgms not reading below 6 at any time, just passing over them with a slight dip). I will take a breath and wait for it to sort itself out a bit better as you suggest Liz.

Of course, it is when I have a hypo that I test, and it's quite different (3-4 mmol/l / 50-70 mg/dl difference) and I feel I should give it a meter reading to correct it... but I should suppress this instinct, right? Wait until I am over the hypo and stable, and it's a fair time for one of the few calibrations, before giving it a calibration reading?

A more general question. Since it has only had one calibration so far, lets just assume my BG meter was on the high side of things for that test, and the entry was say 1.5 - 2 mmol/l high. Does that mean the accuracy of the CGMS will be stuck relatively too high, until it gets more and more accurate readings? Or does it have its own ability to finetune actual readings? Is it worth taking a couple of tests during calibrations, to input a normalised/more accurate figure into the pump?

RE me buying a unit myself, I found out I can basically book in a session with this one whenever I want to buy a sensor... that's great! I thought they might need to ration it out more, I might have difficulty accessing it more regularly if I choose to.

[poodlebone]

The sensor does have a 15-20 minute lag time, behind your meter readings. This is especially true during times of a fast change, such as when you're dropping fast due to exercise, or if you just ate and your food is starting to hit your system. Since the best part of the CGMS for me is to avoid lows, I have my alarm set for 75. I am seriously thinking of making it a little higher, 80-85. Most times when I test and see I'm something like 62 but my sensor says 81, within 10-15 minutes the sensor will have dropped and the number will get close to my meter. Of course, if I didn't treat that 62 I may be dropping. I don't calibrate for something like that, only if the sensor is off by a lot more, especially if I haven't eaten or bolused within 3 hours or so. Never, ever calibrate if there's an arrow (or two, in either direction) on the screen. You will confuse the sensor, as I have learned. If the pump asks for a calibration and you realize that it's nortt really a good time you can ignore the alarm. It will stop showing readings, but once you're stable just go ahead and calibrate and they'll pick up again. This is why I keep an eye on my next calibration time. I don't want to eat lunch and then 40 minutes later it asks for the calibration that I forgot all about. It's happened!

When I calibrate I will sometimes do 2 or 3 meter BGs just to take sure I didn't have some kind of fluke reading the first time. Generally the numbers are all within a close enough range. If I've done 3 tests I'll just pick the # in the middle. If I do two and they're more than 10 points apart, I will often just average them and enter that. Usually I just do 2 meter tests before a calibration.

You will find that after the very first calibration, when you enter later calibrations the sensor will not change to meet that exact number so I guess it does do its own thing. Every so often the sensor is still too far off after a calibration and I will do another. The pump takes your past 4 calibrations into account somehow when it does its thing. I read a trick that if your BG is very stable, you can do 4 calibrations in a row (15 minutes apart) and that should give you a very accurate calibration, as long as there's nothing wrong with the sensor. I've done that twice, when a sensor was just all over the place. 4 in a row brought it back in line and it worked great after that. Minimed, of course, does not recommend this.

[Subby]

Liz, thanks for your invaluable help and ideas. As for my lows, the thing was - the sensor never made it down there at all, even with lag considered, so I guess it just hasn't been doing a great job this day. In fact, it's been showing rock trends and ignoring most of the movements. It was reading as 6 to 7 mmol/l for hours (and my own tests have been in that ballpark) but a few tests on my meter (two meters, actually) and I'm actually 11 mmol/l and not likely to have spiked there in the last 20 min. Sigh. Well, I will get some sleep and see if there is just a little more parity tomorrow. It's still exciting stuff.