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Fasting in Type 1 and replenishing glucose in the liver

Discussion in 'Parents of Children with Type 1' started by nebby3, Dec 14, 2015.

  1. nebby3

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    We inadvertently got some interesting data this week from my dd (and her dexcom). She chose to fast in Friday for religious reasons (disclaimers: she is 13, I kept a careful eye on her all day and this was her choice, nobody forced her to do it). During the day Friday her numbers were beautiful which I guess tells us our basal is set well. Side note: I find that giving low or no carb foods to basal test does not have the same effect. Her body must convert the protein to glucose pretty well so that it is not really an accurate basal test for us. But what really struck me was that though her numbers were great the first day she ran really, really low the next two nights. And actually much of the day in between too though that doesn't show up on the graphs as well. My conclusion: while fasting, she depleted her liver of its stored glucose and it took her a full 36 hours to replenish it. For that period it seemed like no matter how I poured carbs into her she would barely bump up and then come right back down as if her liver were just draining her blood of its glucose to replenish its own stores. Practical applications? Well, if your child ever chooses to fast for some reason, lower basals way down and underbolus for the next 36 hours. But I think this can also apply to unintentional fasts like when one has a stomach bug or when glucagon has been used for a low. Either one will rob the liver of its glucose and the evidence from our mini experiment is that it really did take 36 hours to replenish but that when it was done, it was done, just like that and her numbers were back to normal.
     

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  2. Theo's dad Joe

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    Keep in mind that most glycogen is in the muscles. A 100 pound kid for example would have only about 60 grams of liver glycogen and maybe 200 grams of muscle glycogen, so I would suspect that it is the depleted MUSCLE glycogen. The food is largely going to fill up muscle glycogen. Muscles will supercompensate and pull in more glucose after they have been depleted.

    Also muscles will burn up/deplete fat that is stored around them and in them during a fast, that also will raise insulin sensitivity afterwards. In fact a fast has virtually the same physiological effects as a day of high activity-muscles (and to a lesser degree the liver) becomes more sensitive to insulin because muscle glycogen is depleted as are fatty acids that the muscle has available. Depleting either of these increases insulin sensitivity of the muscle and liver.

    Also, low insulin levels during the fast may increase insulin sensitivity-but not right away. (if someone usually eats more carbs and the fast is not too long).

    It illustrates that basal may not really be independent of how much you are eating though. If you deplete liver glycogen the liver will hit a point where it just does not have any glycogen to leak out, but most people will start turning protein (from food or muscles) into glucose by that point. There IS a limit to how much glucose the body can put away regardless of insulin levels. Your liver and muscles only hold so much, and if they are full then it takes MORE insulin to turn the extra glucose into fat, and more to keep it in fat cells and these also take a long time to happen.

    does she usually eat low, medium, high(er) carbs?
    also wondering if she is a high% basal or low% basal person if you want to share.
     
    Last edited: Dec 14, 2015
  3. Theo's dad Joe

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    I wonder if this is not similar to why kids may go low after being sick for a while. I figured it was inability to absorb carbs, but maybe they get their muscle and liver glycogen and also intramuscular fat depleted during the illness and so they are just more sensitive.
     
  4. nebby3

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    I completely agree about basal not being independent of how much one is eating. At least that seems to be our experience. That is why we don't usually do basal testing. I will say the body turning protein into blood glucose is something we seem to be noticing more just recently -- perhaps as she is now a teen and well into puberty?

    To me is doesn't matter so much whether it is the liver or muscles which are depleted. The point for me was that her body clearly needs a good chunk of time to replenish. The lows, coming and going, were really like turning on and off a switch. There wasn't a gradual return to normal, more like everything just popped back into place. Personally I really wish I had known she would be so low for that chunk of time (I would have gotten a lot more sleep if I had lowered basal) and so I thought it was worth sharing in case others are ever in the same situation (for whatever reason). That is really my main point.

    I think her basal is just over 50% of TDD. I also tend to think we eat lower carb normally (relative to most Americans) but not truly low carb.
     
  5. Theo's dad Joe

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    The most important point is that you saw what you saw which trumps any theory out there. And the situation may apply to me at some point-we have discussed the scenario of religious fasting. Also it is a bit suprising that she was that low because I thought the the body would be turning more protein into glucose and I would have expected the low to happen in the first day, but what probably happens is that as soon as the carbs come back, gluconeogenesis gets shut down, but there is a lot of space to put glucose. Thanks, it is very useful into to me.
     
  6. forHisglory

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    Really interesting discussion. My son sometimes skips meals and I've been wondering how this affects his overall physiology. Certainly its not a complete fast like your daughter, but he is incredibly picky. I place a wholesome, nutritious, and delicious (if I say so myself, and according to the rest of the family) meal on the table and he will flat out refuse to eat it sometimes. Then, ask for sweets later on. I don't battle, don't try to turn it into a power struggle, but just divide our responsibility which sometimes means he won't eat much of his meal and occasionally none if he pouts that I didn't make his "requested" meal. My job- put a well rounded, tasty meal on the table....your job- eat what you need/want of that meal. He's been like that since birth and its very challenging to feed a highly sensitive, low adaptability personality (he's bothered by holes in his sandwich bread, the wrong "level" of milk in his bowl, has to have the same cups, etc.)

    My main point is that I've been worried about times he doesn't eat.......or eats very little since D because of lows. Turning down the basal has been my answer, so your post did help me in a different way.
     
  7. Theo's dad Joe

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    One thing that I have found is that my son would tend to be lower in the morning if he ate a very light or early dinner, but he would spike higher at breakfast. I figured he was turning protein into glucose or making ketones, but he WOULD often tend to run lower the rest of the day. he will however run lower at night if he eats a couple of low fat meals leading up.

    Also thinking that changing basal needs due to activity or dietary changes is just the kind of thing that the AP will be able to manage so well, while now we can only guess and anticipate.
     
    Last edited: Dec 14, 2015
  8. nebby3

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    So the 36 hrs of lows my dd had after fasting were a night, a day and then the next night. Both nights she was low, low, low hovering around 50-55 despite many juice boxes. During the day in the middle there I still think she was mostly low though she did have two big spikes. I attributed these at the time to having way overtreated the preceding lows but I am not sure if it was that so much or her body just readjusting to food and having vast swings. Overall though I think reducing the basal (as we always do for a few days after a stomach bug) is the way to go for us in the future. If we do do that, it will be interesting to see if the spiky highs also disappear.

    Side note: I hate that dexcom alarms when she goes below 55 but then alarms again when she comes back up above 55 because now she is below 90 (which is where we have our low alarm set). On a night of continual lows where she bounces back and forth between 54 and 56 that is just way too many alarms for me.
     
  9. funnygrl

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    How long did she fast for, total?

    I hate the excessive low alarms too! My low threshold is 70, so it might alarm at 69, again at 54, again at 56, then it might bump to 70 for a reading, back to 68 one reading later and another alarm, then a rise rate alarm!

    This morning Dex said 80 when I woke up. Meter said 70. I calibrated, then it immediately gave a low alarm. Hi, I don't think I need that. You wouldn't know I was low if I didn't just tell you.
     
    Last edited: Dec 14, 2015
  10. quiltinmom

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    Thank you for sharing this. We also fast for religious reasons sometimes, and since starting the pump (and dexcom), Ds can fast too. I haven't noticed a pattern of lows afterward; I hadn't really thought about it. Sometimes he will have a low during a fast (which we allow him to treat of course) but I hadn't thought it might have consequences later on (it's so unpredictable, patterns can be tough to spot, or pin down to a specific reason). I will definitely watch for that from now on.

    I'm also wondering how long she fasted. I'm curious how long a fast would have to be to cause this kind of results.
     
  11. nebby3

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    Of course as always YDMV. These were are results but others might not see such dramatic lows.

    She really fasted for about 36 hours since obviously she wasn't eating at night, then fasted all day then had another night. During the day she didn't 100% fast. She had a few carbs a couple of times in order to head off potential lows. Once she had about 5 quinoa chips and then I think later in the day she had 1/4 c juice.
     
  12. wilf

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    Thanks for sharing. Very interesting. The Dexcom data confirms what we've assumed was happening at times of sharply reduced carb intake.
     

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