CGMS accuracy hiccups

It's a bumpy ride... or not.

I find that my CGMS is rarely accurate during the first 24-48 hours. At first I thought it was because it was getting calibrated, and it took a while. But, then, sometimes it would calibrate perfectly by the 2nd reading and then be spot-on till it ran out of battery 6-7 days later. I just want to give props to my last one that was accurate the whole time, 24x7. It took 7 days for the battery to run out, or I would have kept it going longer. Hope there's a few more like that in my future...

I think that when I hit a blood vessel there is some bleeding around the sensor. Since it's meant to read BG from interstitial fluid, and not blood, it's not accurate. I believe when the blood gets reabsorbed and the bleeding stops, it gets more accurate. I have had results that go along with this idea. I always leave them in, even if I notice bleeding or accuracy problems early on. They seem to eventually get sorted out, but it's not immediate.

Today, I turned it off and am going to give it some time before I actually depend on it for real useful data. So far, I've been pretty flat at 90 mg/dl this AM and my sensor has had me at 69 mg/dl with a single down arrow and low predicted, and then a double arrow up at 129 mg/dl predicting an ascent out of range. During the night it showed me going from 81-130 every hour like an ECG. All false...

Anybody else out there have these quirky problems with their CGMS?

I have heard that Medtronic has improved their sensor technology, a lot. That will make a huge difference, when the FDA approves them and we get them. Dexcom seems to be ahead on the development, but I'm pretty hooked on the pump integration, so am willing to wait/suffer a bit.

I sort of cheat and usually behave myself and eat really conservatively the first day of most sensors. If my BG doesn't do much, the sensor doesn't do much and ends up being "accurate". I agree that pump integration > whatever accuracy differential there is. I can get MM to be pretty accurate and it sort of "babysits" me as I'm like "I don't want to eat that and upset the applecart..."

Nathan, I'm having a LOT of the same hiccups that you're having. I started CGM about a month ago and am starting to wonder if the expense is worth it. I have learned to NOT calibrate more than 2 or 3 times a day, and also not to cal when bg's are high or low...(so when do I do it exactly?) My trainer says not to worry, I'll eventually catch on and will love it! She's been right about everything else, I'm crossing my fingers for you AND me! Hang in there!