Lows that just won't quit

My son was dxed almost 6.5 years ago. He’s been pumping for almost 4.5 years and on Dexcom for 3 years. He’s also in the middle of puberty. He’s been experiencing lows at night that just won’t come up.

  1. He goes low several hours after dinner so his IOB is minimal to none.
  2. He does not have any correction IOB.
  3. We run a 0% basal for hours (last night was 3 hours)
  4. It takes an inordinate amount of carbs to bring him into a safe range (last night took 72 uncovered carbs to bring his BG out of the 50’s into a safe range).
  5. He plays tennis, however, this began occurring before he started playing.

To recap:
The number of hours this occurs after his last bolus makes it unlikely it’s an I:C ratio issue, the duration of time we run a 0% basal makes it unlikely it’s a basal rate issue and since it began occurring before he started playing tennis makes it unlikely it’s an exercise issue. Lastly, being 6.5 years post dx makes it extremely unlikely it’s a honeymoon phase issue.

So, this leads me to believe it’s either witchcraft or his pancreas is spontaneously and miraculously healing itself during the night only to fail again in the morning. How else do you explain no IOB, 0% basal for hours and 70+ carbs to treat a low? Who needs sleep anyway, right?

When you mention his BG is in the 50’s, how are you verifying this? cgm only, meter reading, what type of meter, how many fingerstick checks, any physical symptoms? (Sorry if that sounds stupid but when I am troubleshooting something for ourselves, I just like to try and rule out the obvious first so as to be able to focus on what the more likely real problem is.)

How many hours is the low after dinner? What is the specific food being eaten at dinner?

Does your son take any additional medication or supplements whether over the counter or prescribed?

We see (Humalog) insulin effects for quite some time. The main effect is completed in about 3-1/2 hours but there is certainly a smaller tail that extends a few hours past that.

Are you able to post some cgm graphs?

Hi, Tim :slight_smile: I always verify using his meter. He had a Freestyle Lite for years and now uses the Accuchek Guide. The number of checks varies but averages 3-4. Usually no physical symptoms because he is sleeping and I’m the lucky one who gets to stay awake. He uses Novolog and tends to start going low around 3 hours after his last bolus which is traditionally when the Novolog would be leaving his system. He has a varied diet and it doesn’t seem to matter what he eats. He has these weird low nights regardless of the dinner menu, but they happen randomly. No other meds, supplements, etc. Only puberty lol He recently switched to the Tandem X2 which I’m still familiarizing myself with so even though I’m tech literate I’m not completely sure how to get the info from his pump to here.

I have had experiences when I went low while sleeping and the low demanded a lot more glucose to correct. Instead of taking one, two, or three glucose tabs to turn around the low it took seven or eight over a few hour period. I inevitably ending up over-treating the low and had to take some corrective insulin to pull down a subsequent high.

What worked for me was lowering all my pump basal rates. When I finally realized that my basal rates were too hot, the hard-charging relentless nature of the hypos made sense. Basal hypos are much different than bolus hypos for me.

When you turned down your basal to 0% for three hours, your son might have been over-infusing basal insulin for many hours before that. For me, over-dosing basal rates creates a cumulative effect that can go low and very much want to stay there.

What duration of insulin action (DIA) is programmed into the pump? Many pumpers have made the mistake, I believe, to select an unrealistic duration at three hours or so. A more realistic duration of rapid acting analog insulin is around five hours or more. Too short of a DIA will give you an understated IOB. But I’m not a doctor, just someone who has dosed insulin for decades. John Walsh, diabetes author and T1D, published this info on DIA several years ago but I think it still holds true.

Pump settings are not a set-it and forget-it scenario. I’ve found that my body changes and I have to tweak these settings. Insulin to carb ratios (I:C), basal rates, and insulin sensitivity tend to move around over time. People can often ride their pump settings beyond their usefulness and fail to change when their needs do. There’s hardly a week that goes by that doesn’t find me changing at least one of these settings. I imagine going through puberty by itself is making his insulin needs variable. These settings are not sacrosanct.

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Like Terry, id suspect a too high basal rate to be the issue. It could also be greater insulin sensitivity overall at night and the activity may be contributing to it even if this started before he started playing. A little bonus adjustment combined with a lower basal might be needed. Just a guess though.

@Jennifer45, I think the easiest way to cut/paste the pump settings is to upload your pump to T:Connect, open/login to the app, then navigate to the tab . Under the icon representing your pump is a link to . This will have every setting in your pump, and you can easily cut/paste them as needed. If you would like help to view the info on the pump itself, just ask. :slight_smile:

If you also have the Dexcom going to a Smartphone, the cgm graphs are easier to post from a phone.

If he is going low 3 hours after eating, I would definitely modify the I:C for dinner to deliver less insulin. My suggestion would be to modify the I:C for dinner by 20% to deliver less insulin. Do it as a test. See what happens. The cgm makes testing like this great - you can clearly see the results.

Also, in reference to what @Terry4 mentions in terms of the Insulin Duration. When we were on the Animas Ping pump, we used 3 hrs and it seemed quite effective. When we moved to the Tandem t:slim X2, even though the default was 5 hrs, we figured we would keep the same value from the Animas (ie - 3 hrs). However after some time we realized it was not working for us. We gradually bumped it up and now are running at 4-1/2 hrs (Insulin Duration) and it seems much better.

Modifying the Insulin Duration required us to also adjust the I:C for some meals. Be prepared for this. Kind of makes sense when you think about it. I had just not thought that far ahead initially and so was a little surprised. Breakfast - not an issue. Other meals - yeah - I:C needed to be adjusted. A bit of a pain but ended up with much better configuration.

Puberty is a tough time for diabetes when hormones run rampant, especially growth hormones that are most active at night. Adjusting his basal rates sounds right to me. Some basal testing will be helpful if he is willing. John Walsh has good instructions on how to basal test in his book “Pumping Insulin.”

I know you said it isn’t an exercise issue because it happened before he started playing tennis, but before he started playing tennis was he very active? You can burn a lot of glycogen just goofing off outside with friends.

What kind of diet is he on? If he is not getting sufficient carbs and is getting a lot of exercise or has a lot of activity, his body will be using all the carbs he eats to replenish muscle glycogen. Plus all the growth his body is doing. Make sure he is getting enough carbs (as well as protein and fat) for his age, weight, and activity level.

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I also agree that there is probably just too much basal during the 24 hour day. It is amazing how the insulin can just keep adding up. And little things with a pump can really mess you up. Two big ones i’ve Noticed is of course DIA as Terry has discussed and the other that I have found is when you have different carb ratios for different times. Example if your overnight is lower than your breakfast and you eat earlier than usually, your breakfast carb ratio will be at that lower overnight and not the higher (very necessary for many) carb ratio.
Having gone through puberty many, many years ago, how we forget, but I will say I remember it being a nightmarish time for me and my doctor as we tried to make heads or tails out of the urine testing/ blood testing. Nothing ever made sense and we were in reactionary mode through most of it. Being on a pump might make it a little easier but I think it is one of the hardest times of life to manage.
I do think a review of John Walsh’s book Pumping Insulin might help. You never know what you might pick up.
Wish I had an answer, but I know you will get through these very tough teen years and come out stronger on the other side. My parents were my rock throughout. And it sounds like you are the same. Good luck! And when you need to vent, scream, laugh let us know how we can help!


While I agree with everything said here, it does not change the fact that these nights happen randomly and not necessarily frequently. Last night, for example, he was stable all night. I simply get frustrated at lows that last for hours and hours and take an enormous amount of carbs to correct. Even if his I:C ratio was off or his basal was too high, it should not take 3-4 hours of no insulin and 70+ carbs to correct. I know T1D is predictable only in being unpredictable. He has tennis 5 days a week but is only low at night a few times a month. If his ratios were off, it would stand to reason we’d have crazy low nights more often.

What does his team say? Medical check in might be helpful. Nancy

I misunderstood and thought this was a more common occurance.

We have experience something which sounds quite similar maybe in the range of once a month or so. Nothing different from other days but a persistent low in the 50’s or so which does not appear to respond well to carbs. Stop the basal and pile on the carbs and it takes hours and hours and carbs after carbs to raise it.

I never figured that out.

My daughter did tell me next time to just use the Glucagon as she doesn’t want to be drinking half a gallon of Apple Juice at night. This would be in the form of a mini-Glucagon dose for which we have Hospital provided (off-label) directions.

My assumption is that something entirely halted the digestive process so that carbs were no longer being absorbed. Just a guess.

EDIT: Normally we can get about a 40~50 point rise in BG with 1/2 cup Apple Juice (14 carbs) in about 20 minutes.


Your reasoning makes sense when viewed through the lens of diabetes as a static disease. It is not! Diabetes is a dynamic disease. Do you think that sensitivity to insulin remains the same every day? It might be that your son’s overnight basal rates are appropriate for most days when his insulin sensitivity is at its usual level. Then a day and/or night comes along and insulin sensitivity now requires materially less overall insulin to maintain the usual blood glucose traces. Now you’re over-dosing basal insulin and it’s been going on for many hours!

So a basal rate that delivers too much insulin hour after hour drives the BG hypo. This “basal low” is much different than one caused by a mismatch of meal insulin to food. As I said upthread, it is a hard-charging low that takes many more carbs to fix. And it is very persistent. The reason I’m repeating myself here is that your description of your son’s lows matches well what I’ve lived through. It took me a while to figure this out. Others have wintnessed this same phenomena.

Have you read Sugar Surfing by Dr. Stephen Ponder? Dr. Ponder is a pediatric endocrinologist and has lived with T1D for over 50 years. The central theme of the book is that diabetes is dynamic, not static. Static formulas can only help so much, until they don’t. What he encourages is recognizing patterns on a CGM and responding to them in the moment. There’s no waiting three hours to see how good of a guess your meal dose was. He responds in realtime and does a pretty good job of keeping BGs between the lines.

The surfing metaphor is apt. Think about it. No surfer has one (or even two, three, or four) formula(s) for every wave. Instead, s/he paddles into the wave and lets the wave inform her/him what to do next. Surfing is an art and so is diabetes treatment.

If it is random happenings, I would just say welcome to puberty. It is I think the hardest time I had with blood sugars. Pregnancy was tough but a little more predictable. Puberty, no rhyme or reason. Which was why I was in a reactionary mode for much of my teen years. And flying blind a lot due to testing procedures back than.
I do think a check in with medical team, endo, CDE might be helpful. They probably have some good advice that might help get through the unpredictability of hormones. Good luck!

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Make sure you replace the glycogen. Like a fire extinguisher, you gotta make sure it is refilled before the next emergency.

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