The night before last I had an allergic reaction to something in the air at school (I’m taking an evening course), so I took an extra Benadryl on top of the Reactine and Benadryl I already take every day. After going to bed, I woke up to my CGM alarming at around 1:00 AM because I was low. I treated the low, and then decided to set my basal rates a little lower. Well, I fell asleep before I finished editing, and slept through three hours of my pump and CGM alarming and no insulin delivery. So when I woke up and glanced at my CGM at around 4:00 AM, I had shot up to 18 mmol/L. I lowered my basal rates properly this time and got out of the editing screen so that insulin delivery was resumed, and my BG came down with a correction.
Last night I had several lows in the evening and had to eat a substantial number of carbohydrates to keep my blood sugar up. My CGM alarmed again at around 1:30 AM because I was low. So I treated the low, and lowered my basal rates again. When I woke up at around 5:00 AM, I was shocked to find my blood sugar at 19 mmol/L. I thought, “No way did I forget to save the edit changes again!” And when I checked my pump, I found that indeed I had properly exited the editing screen and my pump had been delivering insulin the whole time.
So, what the heck?!?! I only ate 8 grams to treat the low. My only guess is that maybe I had some sort of delayed stomach emptying (carbohydrates not absorbing in the evening when I was trying to treat lows, but then all kicking in hours later). I’ll see if it happens again tonight without eating so many carbohydrates.
We routinely get rises like that from 8-10 grams of carbs, so that doesn’t look out of the ordinary to me. From your message I am guessing that is an abnormal response for you.
Nope, definitely not usual for me to get such huge rises. I routinely use 8-12 grams of carbohydrates to treat lows. One gram of carbohydrate raises my BG by about 0.3-0.4 mmol/L (5-7 mg/dl). So you routinely get a rise of ~30 mg/dl from a single gram of carbohydrate (i.e., I rose about 15 mmol/L or 270 mg/dl from those 8 grams)? That seems super sensitive to me!
This is a typical low and treatment for me. I treated this (near-low) with 16 grams of carbs. I was on my commute home, so I was a bit more aggressive than usual.
@Jen, about one out of forty-fifty sugar corrections, we get a spike which appears to be caused by 3-4x glucose sensitivity. It is very weird, and we have not figured out why. @Millz also has seen this phenomenon.
Yes, my son is very carbohydrate sensitive. His dia friends at camp can’t believe how high he goes with a small carb ingestion. We are hoping he outgrows it (15 currently), but ever since we got taught the 15carbs/15min, and saw our sons response, we changed it to 4/15 and that works well for us.
I believe it’s all related to liver’s ability to store glucose at the time carb correction is taken. A simple calculation: an average adult has 5 liters of blood. Adding 1 gram of glucose to 5 liters would increase blood glucose concentration by 1000 mg/50 dL = 20 mg/dL. Yet, for most adults with T1D, in most cases 1 gram of glucose increases bg by much less, say around 5 mg/dL on average. So what happens with the remaining 20-5 = 15 mg/dL? The answer, I believe, is that instead of going to the bloodstream, about 3/4 of the carbs taken go to storage in liver (in the form of glycogen).
There are cases when liver does not perform such storage and instead almost entire carb correction goes to bloodstream, effectively increasing carb sensitivity by around 4 times. Possible scenarios may include:
In the absence of insulin, liver has no signaling necessary to store glucose (I’ve seen that happen periods of zero-temping of my closed-loop system, 1g would increase my bg by more than 20 mg/dL as opposed to expected 6-7 mg/dL)
Liver may be at the upper limit of it’s glycogen storage, possibly after periods of inactivity
Liver’s storage function is compromised by some other hormones, effectively decreasing insulin sensitivity, i.e. insulin’s ability to stimulate storage
Some combination of the above
More generally, the fundamental problem in bg control for a person with T1D is that we do not know very well what liver is doing or is capable of doing at any given time.
If the carb response is far outside the norm and if the liver may be in some way related, would it make sense to run a full set of liver function tests to insure there are no liver issues which should be addressed?
This is exactly what I have to do, sometimes even 2/15 if it’s only a mild low. I thought it was just because I’m still honeymooning, but now I’m curious to see if I stay this carb sensitive further into this.
It is particularly frustrating because carbs are so easy to find in our world. Also, my son is now at the age where he needs to eat 4-5 meals a day to keep the hunger at bay, and that 11 pm meal really messes with him. If he gets aggressive, he goes low, if he doesn’t get aggressive he stays high most of the night…
That’s rough—I definitely find I can’t have more than a small snack late at night without likely messing up my overnight blood sugars, whether carbs or protein/fat, whatever. Sometimes the low carb food is actually worse, since I think for carbs, aggressive dosing can work ok, but with slow-release food while sleeping, short-acting insulin is unlikely to match up to the rise correctly. I’m trying to just avoid eating late when I can, but sometimes my schedule sucks, and I work one evening a week until 8:30pm, so it’s not always easy to avoid a late meal, and going to sleep hungry just does not work for me.
As far as I know, there are two main hormones that block glycogen synthesis (storage of glucose): glucagon and adrenaline. We (I mean people with T1D) have more or less compromised glucagon production, so maybe adrenaline plays the main role in cases of higher-than-usual carb sensitivity. Biochemistry of glycogen synthesis is complicated, and there could be other non-hormonal factors that counteract insulin action, I do not know.
