I’ve said it many times - I’m not diabetic, I just have a manual pancreas.
The only time I rely on CGM is when I am asleep. The rest of the time I use BG tests.
What you are seeing above is not an algorithm (other than nighttime, when I am not eating). The rest of the time, like 16+ hours, it was manual.
Perhaps we are somewhat in agreement about the idea that an algorithm which relies on a CGM will never be as good as what a person can do manually.
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If you look at the bell curve of diabetics out there perhaps you will see that the vast majority of insulin users can benefit from CGM with commercial algorithm pump. I don’t have the statistics for you but they are easy to find. I have no problem advocating for expanded access to this tech for everybody. I hope your comments don’t discourage some from giving it a try.
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Nice idea, but not true; the pancreas does not know what non-fully-developed-T1s have eaten until a significant time until after they eat. Depending on the responsiveness of the NFDT1 the result will be a blood sugar rise to a level somewhere in the range 150-250mg/dL. Unfortunately there have been very few, if more than one, studies of NFDT1 responses over the time period - such studies require CGMs if real world conditions are maintained. This seems to be the major and I suspect only study:
So careful reading is required to understand all of that and to avoid making stupid comments based on averages. Here is an informative picture which shows averages:
(I’m quoting women because I just replicated this test on one subject, my wife; HbA1c 5.2, baseline fasting BG 100mg/dL, 2 hour post-prandial BG typically around 100mg/dL, one hour post prandial between around140mg/dL and 250mg/dL, 2-3 hour post prandial often hypo.) So the interesting thing is the variation. If you read the full article it turns out that a significant number of people are going over 200mg/dL after one hour:
There is also a distressing number of people who are going hypo. The data refers to 148 people with one, single, 6 day test. My wife’s recent experiences are that the highs and lows are debilitating; we don’t notice that because we are used to them, but my wife is not and they “knock her out” (in her own words). Count hyper lines, count the hypo lines, divide by 148 and that is the percentage of people who, over a 6 day period, become incapacitated, “knocked out.”
No, the non-diabetic “automatic” pancreas does not work. We can do better. Scientists can do a lot more research on NFDT1s (i.e. everyone who isn’t an FDT1) and most likely explain the high rate of automobile accidents, along with a lot else.
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I moved this discussion into its own thread and am open to be better topic name.
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I changed it, @eric’s aphorism seems to sum it all up.
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@jbowler
Thanks for posting this article. It’s extremely interesting, and helps relieve some of my anxiety surrounding going “high” or out of range after a meal. My husband (non-D) always says, “You’re doing the best that you can.” Not a very satisfying comment, because my perception is, I’m not doing good enough!
Is your conclusion that all the subjects that had “high” postprandial BG are headed to T2D?
But you are a great sugar-surfer!!
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Absolutely not; no such conclusion can be drawn based on one set of data over 6 days for each subject (888 meals total). Any conclusions like this would require long term studies and those studies would have to include the whole non-diabetic population, not just the approximately 30% of the subjects who met the “pre-diabetes” criterion (see “Table 1, clinical characteristics”).
The problem with all of this stuff is that “pre-diabetes” doesn’t have anything to do with T2 or T1 diabetes; rather it is a term describing a BG behavior on eating and fasting, quoting the paper:
criteria according to the American Diabetes Association (fasting glucose ≥100 mg/dL and/or glycated hemoglobin ≥5.7%)
So that criterion, well, pair of criteria, manages to capture around 1 in 3 of the subjects; presumably it would extend to 32% of non-diabetic 50 year old Spanish women and 28.8% of 46 year old Spanish men in NW Spain. Is that really useful?
“Pre-diabetic” is a term doctors use when they encounter someone with a fasting BG 100mg/dL or more or an HbA1c of 5.7% or more. It doesn’t mean anything else. The study states:
Those women [* * *] who had prediabetes presented a statistically higher postprandial glycemic response
So think about that… prediabetes means a higher HbA1c and/or a higher fasting blood glucose and it is correlated with a higher postprandial glucose. I find that statement weird; it seems obvious to me that a group of people identified based on higher average blood sugar are expected to have higher blood sugar after they eat. What would be startling is if there was the opposite correlation, but the authors of the paper didn’t test for that:
In females, those who are in a prediabetes situation had a significantly higher postprandial glucose levels. The same fact was observed in the group of males, but without reaching statistical significance.
The study did not seem to look at the variation in response for single subjects; it used data for 6 meals, one per day for each subject but doesn’t seem to compare response variation within those 6 meals with response between different subjects. This is relevant because I observed that my wife’s response varies enormously with regard to peak, peak time and duration with time of day and exercise, the latter was not monitored in the study and the former was factored out by using only one meal (“dinner” I think; probably around 9PM).
My wife’s major excursions are happening in response to relatively small amounts of carbs eaten after getting up; so previously fasting and eating something like a ‘mini bagel’ with 21g of sugar/starch. Larger meals seem (mostly) “softer” and exercise, including just walking around, seems to have a massive effect.
As the authors say:
Future studies are necessary to study in depth how gender affects the postprandial glycemic responses. Increase knowledge of glucose response to meals can contribute to better management of diseases related to glucose metabolism.
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Here is a one-on-one BG challenge test from a few years ago. Both subjects drank a sugar soft drink at time=0 minutes, about 45 grams of pure sugar in there. All of the numbers are from the same meter (and a really good meter too!)
A diabetic vs a non-diabetic. The non-diabetic was a healthy young runner in his 20’s. The diabetic is just some old guy.
Spoiler alert! "Test Subject 1" was me. 
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This is even more true when looping and algorithms that deliver the insulin automatically are relying on the bad CGM data (roller coaster rides anyone?). But I wouldn’t trade the tech for anything. Prior to the tech, I hardly slept for the fear that my 2yo was dying while asleep. Knowing his BGs (even if only in the ballpark) and knowing loop is making its best attempt at correcting, help me sleep better at nights. 6 years in and we couldn’t be better. A1c constantly between 5.5 and 6.0 with 1% low/ severe low and 10% high…we’ll take it!
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That’s one thing that worries me; it is very hard (but certainly possible) to come up with algorithms which are robust in the presence of bad, but temporarily bad, data. The fear is the roller coaster; feedback, in the audio sense of when someone picks up the microphone and the hall fills with a high pitched bell that sounds on every syllable.
Have you seen this happening? It should happen, it would happen if I wrote the algorithm because I don’t know how to make it stable. I suspect the big three are being very cautious because of that possibility, it’s certainly Lawyeria (cf Liberia, not the legal software).
This is one of the advantages of FOSS loop code; we can chose to do something which, while not actually stupid, would certainly transport us to Lawyeria if we did it to someone else. It’s also one of the challenges - producing an adequate insulin pump based on unreliable information is akin to many other engineering problems but more dangerous.
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I guess I fall into that category then with my Tandem pump. The algorithm has allowed me to stop micromanaging my diabetes (unless I choose to) and I don’t because my A1c is now the best it has been in decades. Thanks algorithm!
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Wouldn’t the non-diabetic have that sugar response (the one in Orange?) The orange doesn’t go very high. If it had been me without medication, I would be up into 250 or more pretty quick after drinking that much sugar.
I kept looking on this thread for an answer to this one but couldn’t find it.
Certainly the thread devolved into ad hominem disagreements after this last post so @eric may have been discouraged from continuing.
Can you post up the answer though??
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I think Eric’s point is that an elite (old) diabetic (who he could not name for reasons of modesty) can maintain tighter BG control under a severe glucose challenge than is maintained by a pancreas in a healthy young non-diabetic athlete.
But yes, the line that goes up to around 146 and stays there is supposed to be an example of a non-diabetic BG response.
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Yes, a couple of points I wanted to make about it for this thread.
A non-diabetic can certainly have a BG spike. People are not aware of this because a) the spikes a non-diabetic has are usually very short-lived, b) non-diabetics do not generally test their BG many times in order to see it (like we did in this example), c) non-diabetics do not usually wear CGM’s, and d) the spike might be so quick that a CGM would not even pick it up.
The other point I wanted to make is that a non-diabetic’s pancreas is mostly reactionary.
Yes, there may be a small insulin response as soon as a person begins to eat. But most of it happens in response to a rise in a person’s BG.
So the advantage I had in this comparison was that I knew ahead of time! While the non-diabetic’s pancreas had to wait for his BG to rise before it did anything, my “pancreas” started taking insulin before we drank the sodas.
That was the point of the “manual” pancreas analogy that began this discussion. We can adjust our insulin manually. We have total control, whereas a non-diabetic is always reactionary.
The advantage that non-diabetics have of course is that insulin is secreted directly into their blood, so it works much faster.
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And endogenous has a half life of about 6 minutes.
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@Eric - Is the orange trace yours, or the non-diabetics?
Curious minds want to know a) how much insulin you pre-bolus’d, and how long before you drank your sugary drink?
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Check the spoiler alert!!
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