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The Unreasonable Math of Type 1 Diabetes

maori.geek.nz

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Re: The Unreasonable Math of Type 1 Diabetes

#51

Post by i_cannot_hack »

> A hot bath or shower can raise (then lower) BGL.

I suspect the author has come to this conclusion from CGM data, and therefore also that it is wrong (or at least not a very significant effect).

I also have T1D, and CGMs like Freestyle Libre (and probably also Dexcom) includes a temperature sensor and adjusts its readings based on the external temperature to increase accuracy. I think the changes in blood sugar levels during hot showers (etc) is probably due to the sensor not adjusting quickly enough to the rapid change in temperature, and not a physiological response.

For example, if I go directly from room temperature to my cold balcony, the CGM value will immediately make a huge jump upwards with the next reading, but then quickly revert back down again within the following readings. Considering the 15 minute lag time between plasma glucose and the interstitial readings of the sensor, its unlikely the sensor is immediately measuring a change in plasma glucose – it's simply (over)reacting and adjusting to the new temperature (since the thermometer won't have such a long lag time).

Very hot environments, such as a hot sauna, also makes my CGM readings completely inaccurate.

Re: The Unreasonable Math of Type 1 Diabetes

#52

Post by spaethnl »

I think this article does a great job covering many of the difficulties of T1D.

One component I think was under-emphasized is the fact that correction insulin doses are not based on what your current blood glucose(BG) levels are, but on where you predict they will be when the dose really starts taking effect.

Take for example a current best case scenario of having a Loop system via a continuous glucose monitor (CGM) and pump:

If you took a reasonable guess dose for a meal then check your BG levels after the meal, you may find that you have a steeply inclining graph. Here are two possible cases:

  A. You took a correct dose and the timings are slightly out of sync, but BG will eventually turn around.

  B. You under-dosed and will need to either take a correction dose, or wait a long time for the basal dose to fix it.
It can at times be very difficult to distinguish between A and B, and guessing wrong has consequences. Futhermore, you won't really know which is the case until sometime later.

If you are wrong about A then you did nothing, but really you needed to take an correction dose. You won't find out you were wrong for a while, in the meantime your BG is sky-rocketing.

If you are wrong about B: then you over-dosed and are running low. How much did you over-dose? How many carbs should you consume to correct?

Because your CGM only updates every 5 minutes, and typical rapid acting insulin takes about 20 minutes to really get going, this cycle can play out every 25 minutes or so until you have stabilized your BG. all while you may have unhealthy BG levels, and you may be Yo-yo-ing.

This is very slightly mitigated by using an ultra-rapid insulin like Lyumjev, or Fiasp, which can get going in 15 minutes, giving you a tighter loop.

It would be very helpful if:

  1. ... CGM devices had options for more frequent updates during highs and lows. Tighter feedback loops could go a long way.

  2. ... pumps could dose insulin and glucagon automatically.

  3. ... there were even faster acting insulins. This is tough because most insulins are injected interstitially, which takes time for your body to absorb. Maybe an out-patient implantable pump that could inject intravenously would help?

  4. ... there were BETTER INSULIN PUMP SOFTWARE for calculating doses. I have a Tandem T:Slim x2. I  can tell it how many carbs I am eating. Only that. It doesn't count or learn from: proteins, fats, what kinds of carbs, or what specific ingredients are there, or their ratios. All of this can dramatically effect how quickly your BG rises, bringing you back to the original problem of guessing. It should be possible to select from a database of commercially available food and manually provided recipes.

Re: The Unreasonable Math of Type 1 Diabetes

#53

Post by valarauko »

Trasmatta wrote: post #13
kettleballroll wrote: post #11

Earlier quoted context omitted.

> I will say it turned me into a huge proponent of massive amounts of protein and fiber in my diet (but kinda turned me off Thai food :/ ) Why?

Protein is low carb. Fiber is a carb that doesn't impact your blood glucose, because your body doesn't break it down. Thai food is heavy on noodles and rice, which are both very high carb.

Isn't this true of essentially most cuisines though, to be carb rich? Indian, Chinese, Mexican, Italian, French, etc - the typical diet in most places is heavily skewed towards carb in general. It's a matter of adjusting the ratio of protein-rich foods vs carbs within that cuisine to your needs.

Re: The Unreasonable Math of Type 1 Diabetes

#54

Post by Trasmatta »

mellavora wrote: post #35
sweston4 wrote: post #19

I'm a type 1 diabetic and data scientist. Estimating the causal effect of a unit of insulin or food on blood sugar is an absolute crap shoot. Consider that there's a +/-20% margin of error on the reported carbohydrates on nutrition facts. We might consider this irreducible error that just cannot be modelled (Maybe you could get a calorimeter, estimate the distribution of errors, and reduce that error somewhat). There…

> that would kill you if the resulting low blood sugar is not dealt with. My wife is type I, so I have a sense of what you live with. She bought a book, "The Insulin Murders", which looked at a number of cases where insulin was the weapon of choice. The good news is that it is actually really hard to die from low blood sugar, assuming good medical care is available. Coma to death is > 12 hours, more like 24 or 48. As…

> The good news is that it is actually really hard to die from low blood sugar, assuming good medical care is available.

Except it's extremely hard to get medical care when your mind and body shuts down because of a severe case of hypoglycemia. There isn't always somebody around to call an ambulance.

If you haven't experienced a severe episode of hypoglycemia yourself, you really don't understand fully how it can effect both the mind and body, even if you've seen it in your wife.

And like the other poster mentioned, 6-10% of T1D's die of hypoglycemia. It's a lot easier to die of than you're giving it credit for.

If COVID had a 6-10% death rate, I don't think anyone would be saying "it's actually really hard to die from COVID".

> And I'm not sure a 20% insulin overdose would trigger coma

You can experience hypoglycemia without any insulin overdose. There are many other factors that impact your BG, and sometimes a combination of those will hit a T1D with a severe hypo, even if they took what should have been the correct insulin:carb ratio.

Re: The Unreasonable Math of Type 1 Diabetes

#55

Post by cadr »

i_cannot_hack wrote: post #51

> A hot bath or shower can raise (then lower) BGL. I suspect the author has come to this conclusion from CGM data, and therefore also that it is wrong (or at least not a very significant effect). I also have T1D, and CGMs like Freestyle Libre (and probably also Dexcom) includes a temperature sensor and adjusts its readings based on the external temperature to increase accuracy. I think the changes in blood sugar leve…

I'm going to guess the G6 does not have that correction, based on every shower every day :)

Re: The Unreasonable Math of Type 1 Diabetes

#56

Post by Trasmatta »

i_cannot_hack wrote: post #51

> A hot bath or shower can raise (then lower) BGL. I suspect the author has come to this conclusion from CGM data, and therefore also that it is wrong (or at least not a very significant effect). I also have T1D, and CGMs like Freestyle Libre (and probably also Dexcom) includes a temperature sensor and adjusts its readings based on the external temperature to increase accuracy. I think the changes in blood sugar leve…

Another thing you have to be careful of: pressure on the sensor can drastically effect readings. This is particularly a problem if you sleep on your sensor.

Re: The Unreasonable Math of Type 1 Diabetes

#58

Post by jamiek88 »

MattGaiser wrote: post #38
kahrl wrote: post #27

Earlier quoted context omitted.

The toothless FDA allows for a 20% margin of error on nutrition facts labeling, so it could possibly be one or the other or both. Some products may just have variation. Some foods will be maliciously mislabeled with 19% less calories/sugar/fat but may have little to no variation within the same product.

I am beginning to believe those who count calories and lose less weight than they anticipate.

Yeah 20% is massive if most of your calories come from carbs.

Sensible dieting talks about 10% reductions in intake along with light exercise.

Trying to manage that by those labels would be impossible.

However eating packaged processed foods isn’t a very good way to lose weight anyway.

I lost 180lbs a few years ago by cutting processed food, soda and alcohol out of my diet. Didn’t change anything else.

I presume the carbs in veggies are pretty much accurate by weight a carrot is a carrot (except for water content).

Re: The Unreasonable Math of Type 1 Diabetes

#59

Post by pixl97 »

Trasmatta wrote: post #8

I'm a type 1 diabetic, and this was a helpful post at showing non diabetics why it is so. hard. Non diabetics typically think the difficult thing must be the shots and the finger pricks, right? Not really. The majority of diabetics get used to those things quickly (of course there are some of course that deal with a major major needle phobia that can make it even harder). The hard part is that it never ends. Almost e…

Continuous blood glucose monitor and insulin pump. It's reduce the stress and the nearly dying incidents dramatically. The bigger concern for me in my life now is having a backup carbohydrate supply on me so if I go do something like hiking that I have enough glucose to make it back to the next carbohydrate source.

Of course being able to even afford this in the US requires a certain level of privilege. Supplies are very expensive.

Re: The Unreasonable Math of Type 1 Diabetes

#60

Post by jamiek88 »

pimeys wrote: post #50
jnsie wrote: post #42

Earlier quoted context omitted.

> Although in theory you've screwed up if you need to bolus glucagon. Not at all. There are myriad reasons why one might go low despite doing everything right. For instance, unanticipated cardiovascular activity. T1D is a 24/7/365 PITA and one cannot anticipate everything, even with the best will in the world.

Or the classic: have lunch with your colleagues and then walk back to the office. I hope you didn't take all the insulin in the restaurant, just half and half back in the office. It's a nasty drop otherwise...

Jesus Christ I’m exhausted just reading these stories.

That’s fucking ridiculous.

My aunty was T1D and that was back in the 30’s until 90’s when she died, I never realized what a hero she was. Never once heard her complain thus assumed it was easily dealt with. She used to just disappear after meals for a while. It was like some dark family secret.

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