Friday 9 April 2010


CGMs - Continuous Glucose Monitoring is something I rambled about a few posts ago. The idea is you wear a small sensor which is attached to your skin with adhesive plaster material. This will then feed information through to your pump or a hand held receiver (much like a blood glucose monitor), and this will give you 24 hour coverage of what your glucose levels are up to. It won't replace glucose fingerstick testing, as the machine needs to be calibrated, to ensure that it is still working correctly, but the constant information at your fingertips (or not, as the case may be!) means total peace of mind. It seems to me to be a little like having one of those baby monitors which listens to what your kids are up to in the other room. Because let's face it, sometimes your sugars act like they raided the sugar supply, sometimes they seem to 'tire' out drop on you with little warning and sometimes, no matter how hard you try, they just will not behave!

So I've been doing some research and it seems to me that there are two clear front runners for CGMs. This is of course, just my opinion, but each and every diabetic will need to reach their own conclusions about their diabetes management. This might just give you something on which to base your own research. There are indeed many more options, but these two have struck me as the two biggest contenders for my personal needs/desires:

These two options are:

The Guardian RealTime system
The Dexcom 7+.

Perhaps the Guardian Realtime appeals to me because it is manufactured by Medtronic (the makers of my pump), and therefore the information the Realtime will pick up, will be fed straight to my pump. It won't control my sugars, but from what I can tell will mean that I wouldn't need carry around much more machinery with me And let's face it, when you cupboard looks like this...... need to try and lighten your own load a little!

The Guardian Real Time system can also shut off insulin supply from the pump if you ask it to. So if you suffer from debilitating hypos, or you just want to play it safe, the pump will automatically shut off the supply when your sugars drop to the level you dictate, meaning during hypos, you will no longer be receiving insulin. You will of course still have insulin in your system, but you won't be adding to the problem.

The sensor looks like this:

Pretty smart looking I think. According to the Internet library, the sensor can be worn for 3 days. After doing some research it seems many people use theirs for longer than this, seeing as the approval just means this is how long they can guarantee you can wear it before infection or less reliable readings can occur. My experience is that many people choose to wear them for longer. Reliability will checked every day in order to calibrate the machine, so once it does start to get a bit hazy, it can be changed.

The major drawback to this system is the expense. Four sensors cost £160. Even if each sensor manages to last 7 days, that is still a pretty substantial amount to pay. I have no doubt that CGM will one day find its way into the NHS, but for the meantime, while glucose testing is so cheap and reliable, self-funding would be the way forward. The initial cost is £750, which includes the software, transceiver, 10 sensors and the instructions. This price would drop to £450 if purchased at the time of the pump. But either way, it is A LOT to pay in my opinion, unless the results were dramatic!

Drawbacks I have found so far is that apparently the sensor is not completely affixed to the skin, so it kind of 'flops' about on the surface. Hmm, one thing I like about the pump, is that the needle site is very subtle and can't be noticed. The fact that it is described as 'flopping about' puts me off.

There are also many reviews saying that sometimes putting the sensor in can cause a lot of bleeding if you hit a blood vessel. There is a suggestion that a 'bloody' sensor works better - still, doesn't sound great does it!

I am hoping that I will be able to trial the Guardian Real Time at some time in the future, but after asking the people at Medtronic about how long the initial kit lasted, the company went a little this space.

The second one, and in my opinion the one which has a little more going for it than the GRT, is the Dexcom 7+.

Dexcom has been a long standing favourite of many in the US. Many diabetics rave about the Dexcom systems but until recently, there was no distributor in the UK. Well, after writing to Dexcom and asking them how to order from their American distributor, they advise me that they now have a distributor over this side of the water!

The Dexcom 7+ looks like this....

While the sensor doesn't look quite as sophisticated as the other Real-Time, it sits completely attached to the skin, much like a pump, so there is no 'flopping about' and in my opinion it is less likely to catch on anything.

But perhaps the biggest advantage is that as the name suggests, it is a seven-day sensor. If, as mentioned before, the sensor continues to work for more than seven days, then it will mean even less jabbing yourself with needles and even more information.

I have also written to Dexcom, who I am advised are sending me through some information about costs, how it works etc, so I will be able to fill you in more in the near future.

The biggest difference (other than the sensor lifespan) with these two options is that the information isn't sent to your pump. Instead you have a handheld monitor which needs to be within 5 or 6 feet in order to take a reading. However, if you carry a blood glucose meter, they are similar in size, and mine is rarely more than 5 feet away!

As with the real time I am hoping I will be able to trial one, and in the end, it may all come down to price. I haven't had the information through from Dexcom yet, but my research onto chat rooms and forums seems to show that the Dexcom may be as much as half the price of the real time - see why I'm leaning toward that?

The main thing to remember is that the CGM systems don't offer exact like for like readings, seeing as fingerstick tests take their results directly from the blood, which is the most up to date and accurate readings. The CGMs will take reading from the fluid in the muscles. That is the purpose of the fingerstick tests twice a day to calibrate with the machine. The CGMs will provide you with trend information to show the habits of your glucose levels. The main thing is you would have total information about what your body is doing. Half the battle I have found with diabetes is knowing what is going on. Are you having overnight hypos, did you inject enough for the last meal, do you suddenly go up or down during exercise?
This may be the answer, and seeing as I would never be able to achieve this level of control through any other means, I believe it is well worth a little nosey research!

Whatever the outcome, I am very interested in finding out the benefits of this new technology and the practical help it may provide.

I'll keep you posted and write a little more once I have heard back from everyone, and maybe been given the chance to trial them!


  1. Hmm, I've worn the Minimed version and because it is measuring interstitial fluid rather than blood the readings lag half an hour or so behind your actual BG level. Absolutely no good at all if you suffer from sudden hypos.

    I have sudden hypos and I have no warning symptoms, so have been offered one on the NHS. BUT reading all the research papers etc I noticed a small seemingly insignificant finding - the sensor leaves a little bit of itself inside you each time. No problems have been found due to this, they say. Well, if you are going to be using them all day, every day for the rest of your life (how long is a research study done for?) then I think maybe I'll wait until this problem has been overcome.

    The remark above about blood on the sensor making it 'better' - if the machine is calibrated to read fluid glucose then I would imaging a reading from blood might be inaccurate.

    1. Hey,

      I'm so sorry I onl discovered the 'notify me of new comments' function a few months ago, so hadn't realised you had posted. Hopefully this will still reach you!

      When you say 'a little bit' is that tne enzymes in the sensor, or part of the sensor itself?

      I wondered if you had tried the Dexcom system? They have just released the G4 system and I was advised the time lag is only 5 minutes. It also has predictive alarms, so if you are heading down fast, it should notify you before you suffer from the hypo itself.

      I know what you mean, it sounds off-putting to have a little piece left behind, but I would want more information about exactly what it leaves behind before I wrote it off all together.