Another lack of Accuracy Question

Lee · #1 09-24-2009, 08:10 AM

So, last night her accuracy was beautiful. She was 90, but knowing her activity, I gave her a temp basal decrease to keep her from going lower. Well, she got down to 78, with the CGMS alarming at 79 - I thought, I LOVE this thing. We treated. The darn thing went off every 10 minutes (at 1 am!), but I decided to wait it out, well 30 minutes later, it starts alarming that she is 70 again. I was surprised so I tested, and she was 169.

I am jsut surprised that the CGMS caught the low but not the going back up? We recalibrate, and she woke up this morning at 104, with the CGMS saying 103.

So, does the CGMS usually not catch the going back up after a low? I was suprised by the 30 minute lag time.

hawkeyegirl · #2 09-24-2009, 08:12 AM

It does lag behind, but it should have come up by then. Was she laying on the sensor?

We have our low "re-alarm" set to 45 minutes. It avoids having it realarm every 10 minutes at night!

Darryl · #3 09-25-2009, 04:32 PM

Quote:

Originally Posted by Lee

So, last night her accuracy was beautiful. She was 90, but knowing her activity, I gave her a temp basal decrease to keep her from going lower. Well, she got down to 78, with the CGMS alarming at 79 - I thought, I LOVE this thing. We treated. The darn thing went off every 10 minutes (at 1 am!), but I decided to wait it out, well 30 minutes later, it starts alarming that she is 70 again. I was surprised so I tested, and she was 169.

I am jsut surprised that the CGMS caught the low but not the going back up? We recalibrate, and she woke up this morning at 104, with the CGMS saying 103.

So, does the CGMS usually not catch the going back up after a low? I was suprised by the 30 minute lag time.

Lee,

You'll probably come to find that when treating lows, you just give the carbs you think are necessary, then wait about an hour to see the result on the CGM before correcting again. For some reason, lows treated with carbs can be slow to reflect in the interstial fluid. And if you correct twice, you get a high an hour later.

We get a handle on how many points BG goes up per carb (8 in our case), then look at the CGM trend. If low but flat, we just give the estimated carbs. If dropping more quickly, we project where the low will be 15 minutes later based on the CGM reading, and give enough carbs for that (no more). If we think that an over-bolus or over-basal is the problem, then we add the # of carbs to cover the estimated excess insulin. Usually our dd's lows are corrected using 1-5 carbs, then hour later all looks well.