Off to a Good Start & ISIG Questions (Long!!)

[KarenRI]

Hi,

My son, Nate, started on his MM-RT CGM almost 2 weeks ago. So far, so good!

He is much more accepting of the site insertions, thank goodness. (We did several weeks on the Guardian, and he hated insertion day!). I now put a dime-sized blob of Emla on the area we're going to be using, then cover it with IV3000 and let it sit for an hour. As I load up the inserter, he peels off the IV3000, wipes off the Emla, and ices the spot for a few minutes. He says he can't feel a thing when the site goes in. Yay!

Once the sensor is in, I wipe all around it with IV Prep and cover the site with IV3000. So far, this has worked very well. I let the first two sensors go for 6 days before pulling them. He now has a sensor in that seems to be doing really well, so I'm going to see how much I can get out of it. Today is day 7, and I saw the ISIG was still high (questions on that below), so I carefully pulled off the IV3000, pulled the transmitter off and charged it, cleaned up his skin, which looked very good, and re-taped it all up. I'll see how the rest of today goes. His first calibration is due within a half hour.

The CGM seems to be more accurate when his BS's are running in target range, and also when he trending towards low. (Low is set at 80, high at 220). We seldom seem anything over 220, so we have not been getting much for high alarms, but he had a flu shot, and for three days after the shot, his BS's soared. He ran in the 300's and sometimes 400's for no other reason I could explain. During this time, the CGM acted whacky, and was not even close to being accurate. I think during that time, we could not get a good calibration which I'm sure had an effect on how the CGM was performing.

As far as lows, it was late in picking up two lows over the past two weeks. Nate was in the 60's and he felt it before the CGM alarmed. But we have been getting some good calibrations, and for the most part, the alarm has been sounding when his actual BG is around 81-85, or around 100 with two arrows down. This gives us a chance to give him juice or a snack, and we avoid a low all together!

Ok, about ISIG's. Am I correct in assuming that a higher ISIG means a more accurate reading from the CGM? What would you consider a good range for the ISIG numbers?

Nate's A1C at the start of CGM was 7.2. His Endo warned me we might not get any better than that on the CGM, and not to get disappointed if we couldn't get it lower. (Nate's 12, and in the throws of puberty). I took the warning as sort of a personal challenge to myself. Once we get past the learning curve, I feel I can be a bit more aggressive with his dosing, and with the help of CGM data, I will try to get that A1C lower than 7.2. Again, it's just a challenge I am taking on myself. I did not tell Nate. No need to put any pressure on him.

All in all, it's been a good start. I don't think we could go without CGM now!
Thanks to everyone here and the tips they share. The forum has been a huge help!

[Budapest]

Hi,

I am glad to hear that the MM CGM is working for at least some people. :rolleyes: What is the expiration date of the sensors you are using now?

Ok, about ISIG's. Am I correct in assuming that a higher ISIG means a more accurate reading from the CGM? What would you consider a good range for the ISIG numbers?


Actually, the isig is a measurement of a certain electric current in nA (nano Amps). It is proportionate to the BG. The higher the BG the higher the isig. However during the lifetime of the sensor the proportion changes: each calibration resets the proportion. As the sensor ages the current gets weaker (lower isig) even with the same BG.

I hope this makes sense.

[Lindy]

Karen - sounds like you are doing great! I too feel much more comfortable with the CGM and you can be more agressive. We went from a 7.2 down to a 6.8 after our first 3 months on the Guardian. We have another a1c soon - and we also have a new pump now, so it's been more of a learning curve and am anxious to see if we maintained the 6.8 or went up a bit... or down too.. :)

I do look at the ISIG - but only for lower numbers.. If we are in the 5 to 6 range it typically means the end of the sensor. If I'm questioning the sensor reading I'll check the ISIG number and see what it is.

If we are having a stable BS - our sensor readings are fairly accurate. I'm impressed that you rarely go above a 220 - it's a goal for us to reach. ;) Even during a spike or drop - the trends have always been accurate. With the CGM I can treat more aggressively - except when he is away from me (like at preschool)! Your low alarm may be set too low to catch it with a 20 minute lag time on actual BS readings.. maybe set it at 90 or 95?

We have been going approx. 9 days/sensor - our sensors go bad usually after that and haven't made it to day 12 yet. Although many others have! Another goal. We have been using the arm lately - my favorite site so far!

Happy CGMing!

[KarenRI]

Hi Budapest,

Thanks for the ISIG info. So, when the ISIG drops low, and the sensor is 6+ days old, is it safe to assume the sensor is reaching the end of it's useful life? I think understand it now.

My son is a participant in the Artificial Pancreas Project, so our sensors are being provided by the Study. They have given me a full box of sensors, but I haven't opened the box yet. Currently, I am using sensors from a mix of individual sensors they gave me. I'm quite sure, with my best guess, this sensor ( now on Day 7) came from Lot G037, exp. date: 12-30-07. Others I have from the batch are Lot H297 exp. 2-25-08, and Lot G057 exp. 1-1-08.

Thanks again,

Karen

[KarenRI]

Hi Nicky,

Thanks for your reply!

It's great to hear your son has dropped from 7.2 to 6.8. I feel I can do it for Nate as well, once we get more in tune with CGM.

There was a time when 220 was a regular daily occurance. It still happens, sometimes post-mealtime, & sometimes if Nate miscounts carbs, but it's not often. Prior to hooking up to the CGM, the Study had me follow some guidelines that I thought helped us gain better control prior to heading into the World of CGM, with good I:CHO ratios and basal rates that were working steadily. I'm hoping CGM will help us do even better. I'm sure it will!

I agree, 80 is too low for the low alarm setting. I wanted to set it at 90, but our CDE didn't want my son getting discouraged by being alarmed too much in the beginning. She wants it kept at 80 for now, and will raise it higher sometime over the next several weeks.

Thanks for the ISIG info. I'll keep an eye out for those low ones.

I wish my son would let me try a site in his arm. NO WAY! So we're using his upper butt. It's working well so far.

Oh, and I forgot to mention in my first post. I also bought the Radio Shack microphone/receiver. I feel confident enough that for the first time tonight, I won't set my 2AM alarm for a BS check!

Thanks again!

[Mama2H]

Sounds like you have a great head start and have done your homework :D That 220 is amazing! We still cannot keep the meal spike lower than 250 with 15 minute premeal bolus :( What insulin are you pumping with? I am wondering if we need to switch away from Humalog.
Anyway, best of luck! You will do great :D

[KarenRI]

Hi Mama2H,

Thanks so much!

Nate is using Novolog. Not sure if this is really true, but two years ago when Nate began pumping, our CDE at the time told me Novolog was a "sturdier insulin", performed better in a pump, and lasted longer in a reservoir. It wasn't the first time I had heard that.

We also bolus 15 minutes before. I have noticed a huge difference in his post-meal spikes since doing so. He will spike to 200, as he did tonight an hour after dinner, but most times, he begins coming down after the 1 hour mark, and is usually in the 130-160 range 2 hours post-meal.

It took, and still takes a ton of work on my part. (All us Moms to T1's work our butts off!!) Every night, I examine his log sheets. I circle the highs (anything > 130 pre-meal, and anything >180 2 hours post meal), and put a square around the lows. If I see a pattern occuring 2 days out of 3, I make adjustments. If the >180 happens within two hours post meal, I look at the I:CHO ratio. Other than that, I look at the basal. He's on multiple I:CHO ratios and basals throughout the day.

I also have the CDE periodically check his correction factor (the 1650 rule), because he's growing so fast right now. We've adjusted it three times in the past 6 months (45 to 40 to 30).

All these tips and guidelines have helped us, but they may not be for everyone. It's amazing how different each kid is.

Thanks for your kind words.

[Rachel]

Hi Nicky,
I agree, 80 is too low for the low alarm setting. I wanted to set it at 90, but our CDE didn't want my son getting discouraged by being alarmed too much in the beginning. She wants it kept at 80 for now, and will raise it higher sometime over the next several weeks.


Karen,
Wonderful to hear about your start!

About the low alarm ... I think it would be more discouraging to have the system not help catch a low earlier! My guy is much younger, but we have our alarm set at 110 or 100 during the day. If there is a quick drop going on, that can be an 75 or less on blood, particularly on a day when the calibration is a bit off, which is the case for us today. My babysitter just treated a 42 moments ago :eek:... it was 100 with double arrows down. Frightening to think of what have been at an 80 on the CGM. And even more frightening to think of what would have happened with no CGM!!!!