I am not a type 1 and am waiting to get a CGM, but I have a lifetime of experience with electronic measuring devices, calibration and use. There are definite differences between finger stick BG and that from sensor measuring glucose in the interstitial fluids. There is a lag in the changes. From what I’ve read it can be anywhere from 5 to 17.5 minutes. I’m going to post an interesting snip that does a pretty good attempt at describing the difference between Sensor Glucose and Blood glucose. Interesting which one lags the other depends on whether glucose is rising or falling. Supposedly CGM software attempts to compensate for lag.
I already know that if my insurance approves a CGM for me I will continue to test BG with finger sticks especially if the CGM looks a bit off.
When on the rise, the BG value is greater than the SG that follows behind it. But when moving down the tracks, the BG in front is now less than the SG value.
A few points to remember when using CGM with your MiniMed® 530G with Enlite®:
- SG and BG readings will rarely match and are expected to be different
- A greater difference between SG and BG will be seen when your glucose is changing quickly, such as after eating or after taking a bolus of insulin
And most importantly , always confirm with your BG value before deciding to correct a high or treat a low glucose
Why Sensor Glucose does not equal Blood Glucose | Medtronic Diabetes
I don’t want anyone to be discouraged from using a CGM- we just must be aware of the short comings of any measuring device. I tend to think in terms of trends. I will be glad to get a CGM so that I will feel more comfortable when I am on my road bicycle. I am not usually hypo unaware, but I had one experience on my bike that put the fear of hypos in me.
I was on an easy, not training ride when I thought something was wrong with my bike. Fortunately there was no traffic as I was weaving from edge to edge. Anyone who has experienced hypos knows that the brain is stupid without glucose.
I was close to my cousin’s country store. I sat on a bench and tested 40mg/dl, I ate glucose tablets and it got up to 60, I ate more and got to 70 but still shaky. I went into the store where Teresa was cooking. She knew I wasn’t well. I told her I just needed some time, but the smell of the bacon was a delight. Make me one of those bacon sandwiches and maybe I can ride home.
Sorry for the long post, it is a personal fault.