I’m now 12 days in. As the Dexcom G4 sits proudly on my abdomen, I have to keep reminding myself I’m wearing it! I’m the original Princess and the Pea and I can’t feel the G4 at all.
The sensor is rated for 7 days, so, yes I was naughty and restarted the sensor. It’s still working fine on Day 12!
So far, it’s been about 99% accurate with fingerstick comparisons. It was only more than a bit off, twice. Generally, it’s either exact or within a few minor points of my fingerstick reading – if I’m 5.5 mmol/L, the Dexcom might say 5.6 or 5.7. It’s not showing I’m 8, when I’m in the 5s! That’s amazing considering it takes a reading every five minutes from interstitial fluid and fingersticks are taken from blood!
The Decom G4 has ‘saved’ me on several occasions, when I didn’t realise my blood glucose was dropping. By far the major advantage of this ‘early warning’ is that I can deal with impending lows quickly. For me, that’s a huge bonus. No more feeling like a truck ran over me when a low has been around too long, and I didn’t notice!
The other advantage for me is being able to see exactly when my basal isn’t right. Before, without testing every 5 minutes, I could only guess the exact time the basal starts to be a bit off. Generally, I tend to go low in the late afternoons. Now I can see when this starts.
I’m finding the alarms on the Vibe not loud enough for me. But in a noisy environment, that will most always be the case. The Vibe will also vibrate, so I can usually feel that. I’ve only missed one or two alerts.
Like any other piece of technology I have – iPhone, iPad and so on – I can’t see the Vibe’s screen in the sun. I’ve written about this before. It’s got nothing to do with the Vibe itself, it’s just the way this kind of screen-technology is at the moment. On my wish-list is spoken alerts. Probably not going to happen anytime soon, but that would be really nice.
This is a dream to own and a dream to wear – a 5 year dream, and I can’t believe I’m now wearing one! Where people in the diabetes online community have been talking about wearing CGMs for quite a while, we in Australia had little choice. For someone like me, who wanted only Dexcom, which from my research was the best, it was a long wait.
Here’s a 24 hour reading of the Dexcom G4 on the Animas Vibe’s screen. Of course I’m going to show you one of my better 24 hour readings! If only that would happen every day! Dream on!
On the top-left, it shows the current blood glucose reading. On the right, the time and the current graph setting. This one’s a 24 hour, but also available at the press of a button is a 1 hour, 3 hour, 6 hour and 12 hour. Whatever the last screen you select is the one that shows up as default when you press the button on the top of the Vibe. Pretty nifty if I always want to see a 3 hour graph, or a 24 hour graph.
The two lines on the graph represent my Dexcom G4 “limits”. They are between 3.8 mmol/L and 7.8 mmol/L (68 mg/dl and 140 mg/dl), and the Dexcom G4 is set to alert me when my blood glucose goes out of this range. Those min and max values can be changed to whatever you want between 2.5 mmol/L and 22.5 mmol/L.
Additionally, there’s a screen in that same menu that will show your blood glucose in a large font, with how much insulin is on board. That’s really handy!
If you’re dropping and about to go into a hypo, and you have insulin on board (from a recent bolus), you may need to be more aggressive with hypo food.
If you’re high and you have insulin on board, you may or may not need to give another correction, even though the Vibe will also tell you if you need more insulin or not.
This is truly an amazing and highly recommended piece of technology!
As I mentioned before, all info from the Dexcom G4 and the Animas Vibe can be uploaded to diasend.com. About 3 days ago, I did just that. Here’s a sample of one of the reports – and only part of that report:
This one part (Fingerstick vs CGM) of a very comprehensive report, one of many reports, shows only the top two items from that report, but it’s one of the parts I’m interested in. You can clearly see that the CGM has taken 260 readings each day! Try doing that with a meter!
Why are the numbers different? I might have only taken an average of 5 fingerstick readings per day, whereas the CGM has taken 260 in that same timeframe. The CGM average is far more accurate than the fingerstick readings. Could be that I was taking some of the fingersticks when my CGM said I was high or low. Five readings a day just doesn’t compare to 260 readings! And yes, I’m testing less than I used to without the CGM.
This table (Fingerstick Blood Glucose Averages Over 2 Hour Intervals) in the same report is also interesting. You can clearly see during what interval my blood glucose is at its lowest – between 2pm and 4pm. This is where I know my basal has to be adjusted. However, the first table, is from fingerstick readings. That’s highly inaccurate if you do a fingerstick only 5-10 times a day.
Why is there no number between 6am and 8am? Because I’m usually asleep during that time and don’t test. Easy to explain! Why is the first interval between 0:00 and 6:00? That’s sleep time!
The standard deviation is also interesting. Standard deviation is a number that is higher when the numbers vary a lot in value from each other. Unfortunately, fingerstick measurements really don’t tell the picture very well.
This deviation becomes very meaningful with CGM values because SD, by definition, is highly dependent upon the range of BGs you measure and the number of times you measure.
Compare the first table with the second table.
The second table (CGM Table with Standard Deviation) shows that the standard deviation would not only be more accurate with readings every 5 minutes, but the times where I think my blood glucose is going low, isn’t showing on this table. Why? Because I was able to correct that very quickly, so my averages aren’t all that skewed. Remember, these are 2-hour averages, which could contain a 3.0 mmol/L and a 7.0 mmol/L (that’s not exact).
I wouldn’t be doing any basal adjustments off this CGM table. There are other, more meaningful reports for that. For example, there’s a report that highlights an impending low nearly every day around 4pm. That’s the one I’d be heeding.
The fact that the readings around 5pm show as normal is because I’ve quickly eaten something to bring my blood glucose back up. And I’ve eaten the right amount, in other words, I’ve not over treated.
Gorgeous, isn’t it?
The sheer number of reports available on Diasend makes looking at the whole picture very easy, both for me and for my Diabetes Team. If only my A1C could be calculated on the last 2 weeks! I’m going to ask for a fructosamine test along with my next A1c. The Fructosamine will give results similar to A1C, but over 2-3 weeks, not 2-3 months.
The transmitter part of the G4 is warrantied for only six months, after which I will have buy another one. No one seems to know at this point how long the transmitter will last. It depends on the battery. Could be six months, could be a lot longer. Time will tell. So yes, it’s an expensive piece of kit, especially when the private health funds in Australia, aren’t even considering covering any part of any CGM, but that’s a whole other issue. I was very lucky to have had some money left from the sale of my house and the purchase of my new one, and it definitely went to several good causes, including the Dexcom G4, a new iMac (mine was just too old and I need it for work) and a Nakaya Urushi Kuro-Tamenuri Fountain Pen (which has also been on my wish list for many years).
I’m not sorry for a single second that I bought a Dexcom G4. It has given me insights into my blood glucose control that I might never have had unless I was prepared to sit there testing with a meter ever 5 minutes over 2 weeks, and then getting into some mathematics, statistics and graphing. Even after years of hard work to get my blood glucose looking fairly good… and honestly, the pump has helped enormously… the CGM is going that one step further. And for me, that’s a very important step!