The Dexcom SEVEN continuous glucose monitor has been approved for 7 days of use. I usually get 10 to 11 days of use by restarting the sensor after 7 days have elapsed. Your results may vary, so make sure this works for you before relying on it.
Based on the abstract from the Diabetes Care website, it appears that the results on the 10th day are still fairly accurate. Notice how the difference goes down slightly on the 7th day, showing that the Dexcom is more accurate after it's been in place for a few days.
The median absolute relative difference for CGM versus YSI was 12.6, 11.3, and 14.5% on days 2, 7, and 10, respectively (P = 0.63). CGM performed better on day 10 when compared with self-monitoring of blood glucose as compared with YSI.
I expect to see more papers like this before Dexcom applies to the FDA for 10-day use of the sensors. The good news is that this ultimately means less sensors changes will be needed. It also probably means that Dexcom will raises the price of the sensors.
I do hope that before Dexcom takes this move they improve the adhesion of the sensors. Mine usually look like they're falling off by day 9 and they rarely last beyond day 11 because they peel off.
Have you been able to get sensors to stay in place for longer? What tricks have you used to make this work?
My local Dexcom rep kindly arranged to give me a loaner of the new Dexcom Open Choice system. The main difference with this system is how it's calibrated - you can use any meter and enter the blood glucose values by hand.
I carried around both Dexcom receivers, the Dexcom 7 and the Dexcom Open Choice, for over a week. In this test I set them both to read from the same transmitter, so I could directly compare the results. Here's a short video that shows how to calibrate with the new system.
Below I've also got some details comments on the pros and cons of the changes.
I think this small change is a major improvement to the Dexcom system. It gives you the freedom to use your favorite blood glucose meter, so you don't have to worry about getting insurance coverage for two sets of test strips. The WaveSense Keynote meter that I used is extremely accurate, so I hope to benefit with better control and tighter A1Cs.
Dexcom updated their software so that the modal view is available once again. You can now see the reading graphs for up to nine days of readings. I've used this to see problems that happen at specific times each day. It was the only thing I missed from the first version of the Dexcom software.
I have two minor issues with the new features.
First when inputting the glucose value you use the up/down arrows to change the existing value shown by the Dexcom. The scroll speed for those arrows is much too fast. Most of the time the current value is going to be close to the reading from your meter. So you need to change the value only a little. The scrolling is so fast that it's only useful if the difference is over 100 mg/dL. Dexcom please reduce the speed here.
The other issue is even less important, it's to do with the location of the calibration screen. After you've removed and replaced a sensor the first thing you need to do is tell the receiver. You use the sensor insert screen that only appears when the receiver isn't already connected to a transmitter. Dexcom placed this screen after the calibration screen. It should be placed before the calibration screen. Most users will not be calibrating without a sensor in place.
The Dexcom Open Choice is being shipped to all new customers. Existing customers can pay an upgrade (about $200 currently). Dexcom is waiting for FDA approval to provide a download capability for software upgrades. The hope to get this approval by July and will then provide the upgrade for free to existing customers.
Update: I received the software upgrade from Dexcom so I could give them feedback on how it worked. Read more on my post about the Dexcom Open Choice upgrade. They will start shipping the upgrade to all Dexcom Seven users soon.
Note: I currently own shares in Dexcom, I try not to let this ownership influence what I say about the company or its products.
Dexcom SEVEN is cleared to calibrate with any meter
Dexcom announced today that it had received clearance from the FDA to calibrate its Dexcom SEVEN continuous glucose monitoring system using any approved blood glucose meter.
Once this feature is made available, Dexcom users will no longer need the dreaded six foot plus calibration cable. It'll need a software update to allow input of the glucose meter values. I hope they use a good algorithm to let us input those numbers!
Dexcom expects to make this feature available on new systems by the end of the first quarter of 2008, and to upgrade existing users during the second quarter of 2008.
I know that they've already started trials on their 3rd generation system, but so far there's no news about the upcoming features in the 3rd generation or the likely date for the system.
I know where the week went. After a lovely Labor Day, I've been taking the children to school. Which means I've been adjusting my sleep schedule. And that's just...tiring.
Anyway, here are some random things.
Terry Keelan has a poll on TuDiabetes asking how people tape up their Dexcom sensors. For those not in the know, the Dexcom 7 continuous glucose monitor has sensors that can be used for more than seven days. I previously blogged about how to reset the receiver to do this.
But one of the problems is that about day 7 the adhesive on the sensor starts to fade. So how do you tape it up to keep it on. Inquiring minds would like to know. Have a look at the picture Terry provided
Then go to TuDiabetes and let him know your technique for keeping Dexcom sensors in place.
Some time ago I created the Diabetes Search Engine using Google's Custom Search Engine facilities. I think the DSE provides very useful results when you want to search about anything related to diabetes. Building the engine was a little tricky, so I wrote an article about the process. The article was published today on O'Reillys ONLamp.com web site. Warning, the contents are strictly for Geeks with Diabetes. You have been warned.
Finally, this weekend in Connecticut is the big ride. I've already raised over $10,000 to support the important research by Denise Faustman into a cure for Type 1 diabetes. But you might like to stop by and cheer the riders on. The race is in New Canaan and most riders will be coming back between noon and 12:30. Maybe I'll see you there. I'll be the 50-year old diabetic with the big grin on his face! And hey, it's not too late to support me.
I've posted a video to YouTube that shows how to reset the Dexcom 7 receiver to tell it that the sensor has been removed. You can do this if you want to end a sensor early.
The second part shows how to tell the Dexcom 7 receiver that a new sensor has been inserted. You can do this whether or not you have actually replaced the sensor.
I hope you find the video is helpful. Sorry it's a little shaky.
I got two similar questions recently about the Dexcom 7 continuous glucose monitor (CGM) and I realized it's probably worth summarizing what I know about it for those who might be interested in using one. So here's a fairly long post with most of what I know about this interesting device. Note that the Dexcom 7 is officially approved for use in adults, but there are some folks on that list who are using it successfully with their children.
For the record. I start using the Dexcom 3 in March 2007, after a one week free trial. I switched to the Dexcom 7 on July 24th 2007 and have been using it ever since. After 35 days I'm on my 3rd 7-day sensor, so I'm getting an average of at least 12 days out of each one. Remember the sensors are approved for 7 days of use, but most people continue to use them after the seven days are up. I'll post in the future about how to do this, because it's not immediately obvious for everyone.
There are several bloggers who have posted a lot about their Dexcom experiences. You can find a list using the Diabetes Search Engine. Anthony has his Dexcom Seven blog, and Clemma has her Comrade Dex blog, both of which are very informative.
Trying out the Dexcom
You should not purchase a Dexcom without first trying it out. The cost of a Dexcom 7 system with four sensors is $640. And each box of four sensors is $240. And, no you cannot buy these individually.
I do not (yet) have insurance coverage for the Dexcom or the sensors. I'm hoping to start filing for this sometime during this week. From the Yahoo! diabetescgms group it sounds as if more companies are starting to cover the costs of this system. Unless you know that your insurer actually covers it, you need to consider the ongoing Dexcom sensor costs ($60 each for at least 7 days) before deciding to use one.
On the Yahoo! diabetescgms group, someone pointed out that CGMS users seem to be broken into 4 groups.
Those for whom the Minimed REAL time works well.
Those for whom the Dexcom 7 works well.
Those for whom either system works well, and
Those for whom neither works well.
Unless you try it out, you can't tell whether it will work for you. Contact your endo's office and see if they'll arrange a trial for you. You will need a prescription from your endo before you can get a trial. Originally I tried out the Dexcom 3 for a week, which allowed me to make a sensor change. I think this is crucial, so make sure you get to try out the Dexcom 7 for at least 9 days, ideally aim for 2 weeks. And make sure you get a copy of the software when you're doing the trial, the system is much better when you can actually use the (PC-only) software.
Sensor Insertion
Inserting a Dexcom sensor takes some work. With the Dexcom 7, the insertion is a lot less painful than with the Dexcom 3, but it's still tougher than for a pump. There's no spring-loaded inserter, you just have to jab it in. I continue to use it in my abdomen, but I know several people on the Yahoo! diabetescgms group have used arms and buttocks.
Once the sensor is inserted you connect the transmitter to the back of it. This combined unit is waterproof, and you can shower or swim with it and don't need to cover it in any way. The waterproofing is done by having the transmitter lock very firmly in place on the back of the sensor. You can only remove it using the plastic 'safety lock' that stops you from first accidentally inserting the sensor.
The Dexcom requires care and feeding. You need to calibrate it at least twice each day with a test taken using a OneTouch Ultra meter. Calibrating means you take a test with the OneTouch and then connect the OneTouch to the Dexcom via a supplied 5-foot cable, the synchronization takes about 10-15 seconds.
Alarming
You can change the alarm settings on the Dexcom with one setting for the low alarm (changeable in 10 mg/dL increments) and one for the high alarms (20 mg/dL increments). There's a hard-wired alarm that triggers at 55 mg/dL.
Except for the hard-wired one, the alarms only trigger each time the readings cross the boundary from normal to high or to low. So if your high alarm is set to 160 and the reading goes from 155 to 164, the alarm will trigger. If the Dexcom is reading 210 an hour later and the numbers never went below 160 you will not get another alarm. In the case of the hard-wired alarm, you'll get another one 15 minutes after the first.
The alarms can be loud. The first one is a loud buzz. If you miss it, or don't acknowledge it the next alarm is a loud buzz and noise. This happened to me yesterday and three co-workers in surrounding cubes wondered what it was and whether I was OK. So if you're easily embarrassed, watch out for this. In a recent webcast, the Dexcom CEO mentioned that the next generation Dexcom (no idea on dates) will have must more customizable alarms.
The Receiver
The receiver unit is fairly large, a little bigger than most of the insulin pumps available today. I usually carry it in my jeans pocket. It comes with a carrying case, but this is basically unusable. It sticks out very far from your belt and you can't connect the sync cable to it while it's in the case. And remember that it needs to be within 5 feet of the transmitter, so carrying it in a purse may not work.
The Dexcom receiver must be synchronized with a OneTouch Ultra meter at least twice a day. The recommendation is that you check your blood glucose using the meter before making decisions based on the Dexcom readings. In practice I probably test an average of 5 times a day, so don't expect a huge decrease in finger sticks because of the Dexcom. Note that Dexcom provided me with the OneTouch Ultra when I purchased my Dexcom 3 system, I assume they're still doing the same with the Dexcom 7. I also know that many insurance companies won't cover you for two makes of test strips. So if you're going to use the Dexcom, you're forced to switch from your current meter to the new one. The good news is that the Dexcom software will show you both the Dexcom system readings and the meter readings.
The picture below shows the 9-hour graph from the new and the old Dexcom receivers.
You need to charge the receiver about every 3 days, with the supplied charger. It's about the same size as my cellphone charger. I generally do this at night by plugging it in and then sleeping on top of the charging cable so the Dexcom can be beside me in bed. When sleeping I usually leave the Dexcom beside me because the receiver needs to be within 5 feet of the transmitter/sensor. And leaving it on my night stand means I may not hear it when it alarms.
With the Dexcom you'll get their new data management software. I complained loudly on this blog about the original DM software. The new version is much better with lots of useful and useablestatistics. You can also export the data as an XML file, or a comma-separated values (CSV) file which Excel can read.
What do I think about the Dexcom?
In April 2007, I described this as like having a superpower. And I still feel like this about it. My April A1C, just after starting the Dexcom, was 8.2% and my July A1C was 7.0%, a 15% reduction. I don't think I could have accomplished this without the Dexcom. It's also partially due to using Symlin more, and I really found the Dexcom invaluable to help me manage using Symlin.
For me, this has been a life-changing device. Diabetes management has become a lot easier all round. But there are also times when I want to throw it out the window. If I'm woken in the middle of the night (tonight) by a sensor alarm, it can be very annoying. If the usually smooth graph starts to have a lot of gaps in it for no reason that's also a pain.
But I'll stick with it, and I'm aiming for a further improvement in my A1C.
I hope this writeup helps you some in deciding about this device. Note: I still own shares in Dexcom. I try not to let that influence what I say in any of my posts.
A while ago, some of us on the Yahoo! diabetescgms group were asked to participate in a survey about our continuous glucose monitoring systems (CGMS) and what we thought about them.
This short and readable document includes the following sections:
Key Findings about CGM Users
How Patients Use CGM Systems
Comparison between Minimed and Dexcom
Why Patients Stop Using CGM systems
Some thoughts on Reimbursement
I think you'll find this a useful document and well worth the read.
On a personal note, I'm about to start the reimbursement process for my Dexcom 7 STS with my insurer this week. Can I tell you how much I'm not looking forward to this? Why is this so hard?
Given that my A1C went from 8.2% to 7.% while I was using my Dexcom STS without hardly any significant lows it should be clear this system is beneficial and reduces costs in the long term. I just hate having to argue this all with many levels of insurance bureaucracy. I'll let you know how that goes also.
I've been wearing both Dexcom CGM systems for about 24 hours now. It amazes me how closely they track one another, though yesterday the old one was always about 10 points below the new one. Today I'm seeing about the same difference. You can also see there are some gaps in readings for the Dexcom 7. I think the receiver is a bit fussier about rejecting possibly bogus readings. I wonder how that will look when I'm more than seven days into the Dexcom 7 sensor.
I came across a 19-page HSBC Global Research report(PDF) comparing Minimed and Dexcom based on the ADA conference and a survey that HSBC took. The report estimates there will be about 140,000 CGMS users by the end of 2009 versus about 15,000 today (and 6,000 at the end of 2006). That's a huge growth rate, and you know it will impact insurance coverage. I think it will also drive the demand for software to help healthcare teams interpret the huge amount of numbers they'll see in place of log books.
I hope this quote will come about
We would view any such collaboration between DexCom and any of the leading insulin pump manufacturers – Johnson & Johnson (Animas), Roche (Disetronic), Smiths Group (Deltec), or Insulet – as a positive for both parties, as both companies would better com
Personally, I think that CGM will become the standard for testing for anyone with Type 1 diabetes. Read the report, I think you'll find it interesting.
I'll post some pictures from the Dexcom 7 software later in the week. I did try the new software with my old data values and it worked just fine. So I've much more interesting statistical views of my readings available back to March.
Note: I currently own some shares in Dexcom, I work not to let this influence what I say about the company or its products.
Finally here's a picture from last weekend of some of the lovely flowers in my sister-in-law's place in Rhode Island. What a lovely weekend we had there.
When I got home last night a surprise was waiting for me. No, not the Harry Potter book -- that was earlier in the weekend.
A box from Dexcom was sitting on my porch, the new Dexcom 7 CGMS had arrived. The box contained an updated Receiver, a transmitter, and the new software box including download cable. I didn't get a new recharger, and unfortunately they didn't provide a shorter cable to connect the Dexcom 7 receiver with my OneTouch Ultra meter for synchronizing.
So I read the instruction manual while eating my dinner. Then I plugged the receiver in for a few hours to charge it up. I decided to insert the new sensor around bedtime. And wow that was a lot easier for me. That small change they've made in the sensor needle gauge made the insertion pain feel a lot less for me.
The Dexcom SEVEN transmitter design changed slightly. It now has two small extensions on the back to lock it into the sensor. This much be part of making the system waterproof. This did make it a lot harder to actually lock the transmitter into the sensor. The little piece of plastic left after sensor insertion really just didn't work.
Luckily I have such wonderful stomach muscles (hah!) that I was able to just push the transmitter into place. It was really tough! It'll be interesting to try and remove it in when the sensor is all used up.
I waited until this morning to tell the Dexcom 7 receiver about the new sensor. A lot of people have reported better results if you wait more than 2 hours after insertion of the sensor.
Dexcom has made several small changes to the screen between the Dexcom 3 and the Dexcom 7. All of these improve it greatly. They've replaced the time range on the Dexcom 3 (9:30 AM to 10:30 AM) with just the current time (10:30 AM) in a larger font and 1 Hr in an even larger font. Net result, it's much easier to figure out which screen you're looking at.
They've also changed the screens you use when telling the receiver that a new sensor is available. I think this will mean less confusion between the sensor insertion and sensor removal screens.
I've posted a short (and slightly fuzzy, sorry) video on YouTube that shows some of the differences between the screens. I'll try and most more about differences between the Dexcom 3 and the Dexcom SEVEN tomorrow.
Note: I currently own some shares in Dexcom, I work not to let this influence what I say about the company or its products.
I've spent a good deal of time over the last week on the phone with the local sales rep from Dexcom. I was trying to negotiate either a loan of the Dexcom SEVEN, or a deal where I could purchase it and return it if I wasn't satisfied with the new features promised.
I was disappointed before by a promise made by the previous Dexcom representative and I really didn't want this to happen again. But thanks to the great posts on the Dexcom SEVEN by Clemma, I'm now more confident that I'll really like the new features, and I can live without an improved display for now.
The big outstanding question is how long the new Dexcom SEVEN sensors will last for. I'm on day 11 of a current 3-day Dexcom sensor. So to get the equivalent performance from a 7-day sensor, I'd need to be able to wear it for about 25 days. I don't see this happening. So I'm going to work my insurance hard about reimbursement.
It looks like the new software is much better. The representative tells me that you can export the Dexcom data to an Excel spreadsheet - he'd better be right. The waterproofing will be nice and the reduced gauge needle.
What else should I tell you about? Oh yes, the upgrade price. Officially the entire new system (receiver, transmitter, cable, software, One Touch meter) is $800. They currently have a special upgrade offer for July. Over the last week, I got three versions of the upgrade price.
Last week Dexcom sales told me it was $350. Yesterday the Dexcom representative told me it was $450. But late yesterday when I called Dexcom sales to order the system, I was told the price was $150!! So that was what I paid. I also ordered 4 sensors at the special price of $175 (instead of $240). So for about $343 plus tax I'll get the new sensor, receiver, and software. I'll have to return the old ones.
Other minor piece of new is that they're all out of upgrade kits. So right now I need to wait for about 2 weeks to receive it. Once I do, I'll be sure to let you know what I think of it.
Note: I currently own some shares in Dexcom, I work not to let this ownership influence what I say about the company or its products.
The Diabetes Technology Blog is focused on using technology to life better with diabetes. I review: blood glucose monitors; continuous glucose monitor; blood sugar meters; diabetes software and living with diabetes.
About Me
Name: Bernard Farrell
Location: Massachusetts, United States
I was born in Ireland and now live in the US.
I have had Type 1 diabetes for over 36 years. I struggle with my blood sugar, the same as most people with diabetes.
I wear a Cozmo 1800 insulin pump and a Dexcom SEVEN CGM to track my blood glucose levels.
I'm blessed by God, and every day brings the possibility of a cure.
I do hope that before Dexcom takes this move they improve the adhesion of the sensors. Mine usually look like they're falling off by day 9 and they rarely last beyond day 11 because they peel off. 
