Wednesday, 28 April 2010

The CGM begins!

After blogging on numerous occasions about the benefits and convenience of Continuous Glucose Monitoring (CGM) and after managing to secure a free 12 day trial with Medtronic's Minimed Paradigm Real Time system, the time has arrived for me to sample the world of CGM! The folks at Medtronic were kind enough to offer me a free trial, which I gladly accepted. I did try to get a free trial with Dexcom (the other CGM system which I feel is at the forefront of the market), but unfortunately they made me no such offer, so although my future blogging will hopefully give you an idea of what CGM can offer, it won't be a comprehensive comparison of the differences between the systems currently available. But here goes as far as the Medtronic system works....

I arrived excited and ready to go this morning, keen to get going on something I'd been avidly researching for months! I was met by the Medtronic rep who was kind enough to fit me in around my work pattern and had arrived nice and early to meet me. Thankfully my DSN was also there, which turned out to be a blessing as she often asked questions about the system which probably wouldn't have occurred to me. I'm sure she was asking for my benefit, so I didn't make any silly mistakes, but she hid it well under the guise of not knowing too much about it herself.

My initial impression of the equipment was that the whole sensor and tramsitter was smaller than I was expecting. It was around the size of a fifty pence piece, and although it is 'bulkier' than the infusion set for the pump, I didn't expect it to be quite as small as it was. The equipment to get the thing in though, was HUGE! It looked like some sort of industrial piston - and looked like it would be pretty painful to insert! In fact it didn't hurt at all. It felt a little like someone had flicked my stomach with their fingers, but I couldn't feel the needle at all, which is always a bonus as far as I'm concerned.

As for setting it up and inserting it, it's definitely more fiddly than putting the pump in. There are a number of tags and flaps you have to pull off, and in the right order, all the while being careful not to jolt the sensor too much, because apparently this can 'upset' the enzymes in the sensor, causing it fail. But I imagine that's just something you have to get used to. I remember when I put my first infusion in I was all fingers and thumbs, convinced that if I did anything wrong something drastic would happen! I'm pretty sure that after a few times doing it, you become a dab hand and the whole process is over in seconds!

Once the sensor is in, you need to wait around 15 minutes before attaching the transmitter (the bit which sends the results wirelessly to the pump),because the enzymes in the sensor need to become wet. I tried several times to attach the transmitter but every time I tried the sensor wouldn't 'flash', meaning it wasn't quite ready! The rep advised me this could mean I was dehydrated, so I had a drink of water and carried on trying until it worked. It actually took 2 and a half hours before the sensor was wet enough to start 'sensing' under the skin. I was surprised it took this long seeing as I was advised that 15 minutes normally does it, but still, I was doing my normal blood tests anyway so it wasn't really a big deal.

The first time I saw the light flash, I then pressed 'link to sensor' on the pump menu and got the ball rolling. After this point you have to wait two hours in order for the sensor to 'bed in'. When it first asks you for a reading, you have to do a blood test and enter it on the pump in order to calibrate the sensor with your blood glucose. This is so that the sensor can 'learn' about your sugar levels, and when there is a change, the calibrations should mean it is as exact as possible.

After the initial calibration, within no time at all I was receiving real time information about what my blood sugars were doing. At first it was excellent. My sensor glucose was 11.2 at one point while my blood glucose was 10.5. As the sensor reading is approximately 15 minutes behind the glucose reading, I was pretty happy with this result. It would certainly be precise enough to react accordingly, which is the whole point, right?

I have run into problems slightly later in the day, after I narrowly avoided a hypo earlier, thanks to the hypo alarm on the pump. The pump alarmed to let me know that I was 4.4mmol. I tested my sugars via blood and got a 4.7 reading. Close enough! However, I later re calibrated the sensor when my blood glucose was back up to 6. It was around 5 hours since my last calibration and I hadn't eaten, meaning it was a good time to calibrate again. I was warned that in the first 24 hours you get a few odd readings, because until the sensor has been calibrated a number of times, it won't be as precise.

The problem is, the sensor has been alarming for about 3 hours now and currently thinks I'm 2.2mmol! I have checked and double checked, and haven't gone below 5.6mmol so far. But, it could be because after avoiding the low and eating some fruit, my sugars were rising a little too quickly. It's not ideal to calibrate when your sugars are changing rapidly, so the sensor probably thinks I haven't recovered from the low yet. Really, it's just doing its job and seeing as it has only been calibrated twice, it is just going to take a little longer to get set up!

That being said, while it was good, it was fantastic to look at the pump and with the touch of a button, be able to see a reading, as well as trend information and a graph showing what my sugars had been up to for the last 3, 6, 12 or 24 hour period.

So far, apart from the current issue, I can definitely see the benefits of wearing a sensor. I will recalibrate in another couple of hours and hopefully the sensor and my body will begin to agree! I will post again in a couple of days to chart my progress and how I think it's going.

Over and out.

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