Rebound -- detected on your CGM?

Having never worn a CGM, we often are left scratching our heads when we see a random high number on our son's blood glucose test. There have been many times when we have suspected a rebound. However, I looked it up (Somogyi remound) on Wikipedia and there is a section labeled "controversy" where it says that there is little scientific evidence to support the phenomena.

Have any of you tracked a rebound with a CGM? In other words, have you seen cases where it indeed happened?

I really hope it exists. I don't like the thought that a low that isn't caught will mean major, major, major issues. Not that I am relying on it or anything, but I'd like to think that there is some type of body mechanism in place in case he were to drop too low between nighttime checks.

 

My son has worn a CGM 24 hours a day, 7 days a week for 3 years. We have never once seen a rebound. I think they happen, but are much, much, much more rare than people think.

 

My daughter wears her cgms 24/7 and yes, we've seen a rebound on the cgms. I know one was a rebound, but there are times you see things that COULD be rebounds but are not..If you put pressure on the sensor, you'll get a rapid drop to a false low then a bounce back up.. to someone just looking at a cgms and not knowing what they are seeing it could be mistaken for a rebound.

 

Interesting stuff......There have just been so many times where we have felt that there was no way he could have gone high --- not even enough carbs ingested to bring him that high even if we didn't cover them at the last meal --- so we assume it was a rebound.

Can't wait to hear more from others.

 

There are many reasons a child can go high. Off the top of my head: overtreating a low; misjudging carbs; bolus error; meter error; insufficient basal; random growth spurt; adrenaline; a full moon ; etc., etc., etc.

When we misjudge carbs or miss a bolus, Jack will always go higher than he "should." What I mean by that is illustrated as follows: One carb raises him about 8 points. So if we underdose by 10 carbs, that should just raise him 80 points, right? Nope. We find that when he gets above 200 or so for any prolonged period, basal that is usually sufficient is no longer enough. So you've got the rise from the carbs, and then you have a bigger rise from insufficient basal and then you get insulin resistant. So underdosing by 10 carbs can lead to a 300 easily.

I don't find rebounds comforting in the least. They scare the bejesus out of me.

 

I don't find them comforting....but by the same token, I'd be somewhat comforted to know that they exist. It scares the crap out of me that I might someday over bolus him or sleep through a nighttime check. It's not that the existence of this phenomena would make me any less vigilant, but it might give me some small degree of comfort.

 

I'd love to see some confirmation of this, too. That makes some sense to me. A carb tends to raise Matt 7.5. Many times, it works out very close to that. Yet as you said, there are times when we apparently misjudge when covering his carbs yet the resulting blood glucose reading is nowhere near what we would expect. As you said, this situation can lead to an unexpected 300.

Matt's doctor just told us that he is going to be a test subject for a CGM. The company rep is going to lend him the CGM, I assume so that she can showcase it to the doctor, who apparently doesn't use that company at this time. I can't wait to see if he will like it, and what type of information we can get.

 

Some parents are certain that they have observed rebounds in their children. What you should know is that the only controlled studies on rebounds in T1 subjects (at least all the studies I have been able to dig up) have shown that rebounds from low BG do not happen when monitored on a CGM, and to my knowlege no one here has ever documented a rebound on a CGM that was not accompanied by carb intake.

We, personally, have never observed a rebound in 4+ years of 24-hour CGM use, even on those days when BG has dropped below 40. Convsersely, we have seen BG shoot up quickly into the 200's to 400's following stable BG's at levels such as 100 or 120. It would be tempting to explain these as rebounds, except we have a CGM so we know they are not rebounds.

Even if had your child demonstrates consistent rebounding from low BG, it would be a great risk to assume that an overbolus would somehow correct itself, or a night time check could be skipped. Rebounding is so little understood or documented that even if it does happen, we don't know under what conditions it happens or when it might now.

 

I cannot recommend the CGM enough for a LARGE degree of comfort in this respect. I know there is virtually zero chance that Jack will rebound or seize or have a dangerous low while wearing his CGM. At this point, it is non-negotiable in our house.

 

I have one on cgms, I just can not remember the date.. Her endo and CDE both agree that it was a rebound.. infact, they were the ones that brought it up that it was a possible rebound and wanted to know what else was going on at the time. After getting the rest of the info they both agreed (seperately, two different conversations) that i was most likely a rebound... I can remember the coversation, but I can't remember the date so I can look it up or exact details.. but I know we all discussed it.. I remember being surprised about a rebound....

 

I have seen them, if what you are referring to doesn't mean a rebound high. My daughter has had nights that she decided to shut off her alarms without doing anything to treat the lows. One of those nights she stayed low almost the entire night, and another one she woke up at a normal bg. She doesn't normally have any lows from laying on the sensor, so I do trust that these readings are correct. I had a couple of serious talks with her about what could happen, but when she sees the end result waking up fine, it makes it difficult. She can spike high one night and go low the next, so we really need the CGM and need her to respond to every alarm with the proper actions. I cannot imagine living without it, and will do everything in my power to assure that she never has to. My son has the Navigator and I feel that it is equally important for him. He doesn't have problems at night now, but does not feel his lows and never has. He has to consume a lot of carbs to treat his lows, so no way to check for rebounds on him, but I don't believe that he ever has them.

 

We have seen what could be rebounds.

The pattern is a deep or fast low, followed by a nearly vertical line to higher than treatment would warrant, then a high that needs less insulin for correction that its number would warrant.

It is absolutely true that insulin resistance (for both basal and bolus) following a high can cause highs that are "too" high for the carbs. We see that also. In this case, there does not seem to be time for that 300 to "cause" a 450. It is a very fast movement. Also, when we have resistance we tend to need much more insulin, in these cases we seem to see less. But I could just be seeing what I'm expecting to see, since we don't record numbers and analyze them later.

I also see patterns that seem to be nonrebound rebounds. She will drop low (60?) and have a significant amount of insulin on board, or she will drop quickly, and then her body seems to be adding either insulin resistance or glucose into the system. She will not, however, hugely bounce from that. She will simply rise in a way that doesn't "make sense" -- e.g. without treatment (let's say, for example, that I choose not to treat an 80, find five minutes later she's 60, check her bg by fingerstick to make sure CGM is right and find she's now 100 -- I attribute that to lag time on the Dex, and sure enough ten minutes later without treatment Dex will show her rising -- just a made up example). Certainly, I could be wrong about the cause, it could be a mistake in the CGM reading, something like that.

I think it's certainly a hazard to assume a rebound with 400 and undercorrect. However, we have definitely seen that with 400s in some circumstances it is a hazard to correct as you normally would. Seems to me that whichever way you "err" it makes a lot of sense to simply keep looking and correct whatever your correction was if necessary.

I think each person's alpha cell preferences are going to be different. I don't know if true rebounds occur, since I can't see into the body's processes and can only extrapolate from results, I'm never going to know. Studies help, but I think there's enough variability in individuals that they can't be relied upon entirely for things like daily care -- you simply have to factor in what "works" with what "should work". I will say that in our little study of one we could, of course, leave a fast, deep low and watch the CGM to see if she recovers without eating. This would not prove that rebounds could not happen, since it might not happen in this instance but might in another, or might for another child. But I supposed if rebounds do happen I could prove it that way. Ain't up for that experiment, though!

I will say that our endo's attitude seems to be that alpha cell involvement can happen with a low and "rescue" the child from seizure or unconsciousness. However, he definitely says that doesn't mean it will happen, and he's wisely never speculated on how likely it is to happen. In individual cases, I believe they know pretty definitively that it doesn't happen for some individuals at all, and for those folks I think frequent serious hypoglycemic episodes are a huge challenge. Personally, I don't see how we wouldn't see tons of cases of unconsciousness from lows here all the time if the body helped not one whit with lows, ever. I'm diligent, but Selah has often been in the 40s, it seems unlikely that in three years we've never had a period of unconsciousness simply because I caught them all first -- I ain't that good.

 

I have seen them on our CGMs, when she wears it. I even posted one here once. Always overnight.

A rebound does not necessarily make BS shoot through the roof. It will raise the BS 7 to 8 times the trigger #. We have seen a 3 hour steady 60 on the CGMS with a quick climb up to the sky. And I mean it went like _______/.

We have also seen a steady bs in the 120's for a few hours, a plummet drop to the 30's and a super quick climb to 215ish.

While some folks do not believe in the existence of rebounds, there are a few posters here who have actual graphs that show them.

And given my child's history, I find rebounds incredibly reassuring.

 

Interesting. We have a CGMS that we've only used sporadically. I SWEAR though that we've had rebounds but never have caught one for proof.

I want to be able to have the confidence in the CGMS that many of you exhibit. That will be yet another of my summer goals!

 

I have no confidence whatsoever in the accuracy of any one CGMS number. At the same time, I find it an invaluable tool.

Our endo didn't want us using the CGM because it was so incredibly inconsistent in kids Selah's age, in his experience. Thing is, he was right about that, but wrong that it would be dangerous or unhelpful because of it.

I compare it to our standard method of keeping a regular eye out for bg variation. Sure, we normally test, but in between tests we don't just forget about bg. We pay attention to their attitude, what they say, how they look, how tired or agitated they are, how hungry they are. We use all these indicators to determine what their bg might be doing, and if it seems to be doing something that needs addressing, we test.

Same with the CGM for us. We watch it to see if it might tell us what the bg might be doing. It's about as reliable some days and seeing if she has circles under eyes. But it's additional information. So that if reason tells me she got a lot of insulin for breakfast and might go low, and her pale face tells me she might be going low, and if CGMS tells me she's 55 and dropping -- then I'm confident in thinking she's low.

My unsolicited opinion just is that even if you don't have confidence in the CGM itself, it can still do great things for you. I wouldn't go without it!

Sorry for the semi-derail!

 

If you mean a large upward climb from a low BG with no carb given, no, we have never seen that.

 

I have. I've seen numerous lows on my monitor that either I was asleep through or else was in too much pain and did not treat, or even that didn't really quite go low, and that then spiked up. It's never been an extremely dramatic spike upwards but it really seems (and especially did in 2008 when I first wore a CGMS) that my body responds to lows in some ways. I think that response from my body has become a lot more muted since 2008, which makes sense- all studies on hypoglycemic response in type 1 diabetes shows that it deteriorates in the first few years after diagnosis.

 

I've seen a few things which looked like they could be rebounds, but nothing conclusive. I'm no more likely to spike high from being low than I am to just randomly spike high from being in range...

 

I am late to the discussion, but I've caught several... and yes, some treated without carbs. All of them have been overnight. Any spikes I've seen during the day can usually be attributed to "something"... but overnight, not so much.. I don't personally believe that using a modest amount of carbs (12-15g) can really account for a 300+ rise. I have a really bad habit of just shutting up my dexcom when it goes off at night, because usually it's reading low and I'm not really "that" low (like mid-high 70's, which I don't feel needs treatment)... but occasionally those alarms are real and I'll be as low as the dex says and wake up 350+ a few hours later. Ironically it's the high that usually wakes me up later, not the low...

 

I have read some of the studies you are talking about...they are done on adults. Not kids that have been playing sports. I would think a rebound in an adult would be VERY rare. Just saying...Seth only has them when playing sports.