After a cooperitive effort between my durable medical equipment provider and my endocronoligist, my insurance company (HAP) decided to cover the cost of the CGM transmitter, sensors, tape and training. I went on the program on December the 15th with much anticipation. I experienced several lows that required emergency room visits and a broken ankle from one of the times I passed out from one the lows. This all occured in the passed year. My wife was also looking for some relief from coping from my lows. Since the 15th, I’ve changed my site twice without any problems following the instuctions from the trainer and the manuel. My problem so far are the wide variances between my meter readings and the readings being sent to my pump from the sensor. Many times the differences range as high as 60 to 100 points. Very few times, I’ve found the difference to be less than 10 points. These differences can be sometimes higher or lower than my BG. I am disappointed with the reliability and the consistency of the CGM program so far and am close to shipping it all back. I’ve been a diabetic for over 40 years and a pump user for 10, so I think I know what I’m doing. My trainer has been helpful but cannot give me a reason for the wide differences and unreliability of the readings. My last A1c reading was 7.3. I’m wondering if anyone else has had similar experiences with the CGM and what they have done about it. My wife and I thought the CGM was going to help with giving us clear and reliable low warnings but it hasn’t so far. HELP
Jim:
I’ve been using my Dexcom CGM for three years and I cannot say enough nice things about it. It IS a brand new technology, and, as the saying goes, it ain’t perfect (yet). My sensors are said to last for seven days. My experience is that for the first two to three days, the readings are almost irrelevant because they stray too far from those of the glucometer. Then it stays reasonably accurate for another week or so, and its readings match those of the glucometer. Days 6-10 give me nearly perfect readings. If I can manage to keep my glucose levels fairly constant I get good use out of the CGM for as many as 19-22 days before I feel I have to change the sensor. Give it some time, and appreciate the fact that this is new territory. (I’ve gotten my A1Cs down to 5 - 5.2 since I started on the CGM.)
Jim, there are three brands of CGM. Which did you go with?
I have the Freestyle Navigator. I’ve been pleased with its performance, but even more so with their customer service. Every time I have had an issue with the receiver or with a sensor, they’ve sent a replacement out. I’ve had it under 8 weeks and I’m on my third receiver already. They replaced one when I had trouble with the screen and another when a hot bath gave me errors due to the temp of the skin changing. So have you contacted their support team about a replacement?
Also, it’s critical that you not calibrate the system while your blood sugar levels are in flux - like after a meal. They should be in your target range and stable when you calibrate. You also have to take into account that there is a lag time between the interstitial glucose level and the blood glucose level of anywhere from 10-30 minutes. If the CGM readings say you’re dropping and you’re actually rising, then the system is bunk. But if there is just a discrepancy between the BGs and the CMs, it might be the lag time issue.
Melissa,
My pump, sensors and transmitter all come from Medtronic. The pump is a paradigm 722 model. I ve never had any issues with the pump for the 4 years that I’ve had it. I calibrate before I have a meal and before bed which is at least 3 hours even after a late dinner. So i think my blood sugars are stabile and at or near my target when I calibrate. I was thinking lag time also but haven’t been able to pin down how long it is in my case. My problem is with rationalizing the extra work involved with this technology against the results received thus far. Am I asking for too much?
Jim, I’m with Mellisa: unless you’re doing infusion sites on the same part of your Torso as your Sensors, it just might not be the “best one” for you. My own Endo, as well as the famous pump trainer John Walsh, and I all had sucky results from Minimed-- and pretty decent results from Dexcom.
From the other forums and boards on the web, from people I’ve gotten to “talk” with, it seems to be Abbott > Dexcom > Minimed for accuracy and reliability of readings. Abbott seems to be doing an awful lot of hardware swaps on receivers and transmitters which just don’t work right, but when they’re working properly, they’re fantastic-- nearly ALL the adults who have discussed it after switching to Navigator from Dex or MM say that the accuracy is AMAZINGLY Better. (Even when they’d been “pretty satisfied” with their previous product.)
If you are doing infusion sites within even 6 inches of your Sensor locations, you need to stop doing that-- move your infusion sites down to your thighs, or back on your butt, or put your Sensors on your upper butt cheeks instead. They “say” that you can get OK readings within just two inches of older infusion sites, but nearly everyone needs to keep them much further apart. (And it’s older sites too, not just your active infuser.)
The other thing which you should do IMMEDIATELY, if you haven’t already solve the problem in the last 10 days, is get the MiniLink replaced. MiniLink does the actual ISIG measurement, the Receiver only does the graphing and controls and 3-day timer countdown (and stuff like that.) Minilink is much more problematic than the R/T portion, there have been lots of failures.
I’ve had great customer service from Minimed, particularly from “Moses” who even studied my Carelink results and called me back a couple of days later with recommendations.
I’m sure you’ve read all the documentation, but the key is calibration. Don’t calibrate if you are about to workout or just finished, about to eat or just did, or if your sugar is changing rapidly. Moses taught me that you can simply disregard a “Meter blood glucose now” message if the timing is bad. He also explained that if your calibration is way off the sensor number, it may be due to the 20-30 minute/20% variation issue, which may result in a delay while it settles down again.
And, though I was informed by a nurse trainer that she has patients wearing the sensors for 2 full cycles (6 days), my results are poor by day 4 and my skin isn’t too happy either. 3 days it is from now on.
Hi Jim, From what I understand about the science of the CGM many things can affect it’s readings. Including absorption of the area of fluid some area’s are a bit dry compared as well as some area’s hold fluid longer within the tissue. I don’t use my CGM for exact BG readings I use it to show me trends. If I get an up arrow or alarm I check my BG with my meter so I can see what is happening. If I get a down arrow or alarm I check to see what is happening. I know the CGM’s are less accurate with rapid falls and rapid rises. Most times my CGM is close to my meter with the exceptions of fast ups or downs. It has saved me from so many lows not because it was exact but because of the warnings. I am not sure what others expect but that is what I expect from mine and what I wanted because it allows me a bit of safety to handle my BG better. I need that because so many low’s made me afraid of normal 
Be loved
FWIW…I consistently get 6 days (two 3 day cycles) out of 1 sensor unless results (usually resulting from low ISIG numbers) during the 1st cycle were crummy. I personally haven’t had good results using a sensor beyond 6 days.