This is really interesting. I think a lot of this helps to explain why I'm seeing higher than expected numbers after commuting home (a 20 min load-bearing walk, usually 4-5 hours after eating anything at all - definitely counts as exercise!), but lower numbers after just a 10 minute pace about at home having eaten only 2 hours prior. If I chill out on the couch/faffing about in the kitchen after getting home for an hour, levels drop to where I'd sort of 'expect' for that time of day/after eating. Obviously apples and oranges, particularly in terms of starting BG, but it's a consistently weird thing that feels backwards. I suspect my walk home looks more like HIIT exercise to my liver than a more moderate exercise.
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Technical/scientific curiosities - who to ask?
- Thread starter Amyfaith
- Start date
This is an incredible amount of information - thank you so very much! I've popped my responses below.
Q: Is one or two hour post eating more important?
A: Each gives different information, but for a wet finger in the air interpretation, I would suggest the 2 hour gives a better idea.
Reply: That's my sense as well. Almost how far 'off' we are from our 'normal' BG level to some extent, I guess?
Some feel the one hour point illustrates the top of the rise, but fat heavy meals this may simply not be the case. Fat slows the blood glucose rise, so any peak may come much later than an hour (or in some cases, even 2 hour) mark.
Further reply on this: HA and I just saw this happen the last couple of nights (it's burger weather, and I like a cheese burger and tried a fathead bun... that was a little too much). Nothing especially high (upper 6s/low 7s from a starting point of about 5.4/5) but it took AGES to come down.
Q: Does the rise at 2 hours matter so long as it stays below 8.5? (Does the 2-3 mmol rise max come from anywhere? Do I need to minimise the rise at 1-2 hrs or just keep it to 3mmol/8.5 max?) I ask because all meals are well below 8.5 in general at 2 hours, usually below 7.0, and my rise is usually about 1mmol, so can I eat a little more normally or should I minimise ups and downs? (I am tempted to find out what my carb tolerance for 3mmol rise max actually is…)
Is it specifically how *long* BG is raised rather than how high it is raised that we are trying to impact? (Eg: spike to whatever - but it needs to come down to normalish right-quick, thus a blunted peak?) or am I oversimplifying?
A: As has already been said there's no definitive answer to this at the moment. Personally, I go for time in the Bell Curve as a measure of the impact of any given food. Again, personally, I was influenced by my reaction to pasts. Eating pasta, I found I experienced a very modest rise, but rise was very sustained - well in excess of 2 hours, or even 4 hours. So, for me, pasta wasn't doing me any favours. I just gave up pasta to be honest.
In the intervening period my Endo has recommended a strictly gluten free diet, due to another condition.
Reply: This is of course the frustration of just doing finger pricks (I'll get to the Libre below). Really hard to know for certain if I value my fingers/my savings account. I've done the odd bit of every 20-30 mins after eating just to see but can't do it constantly.
Q: Hba1c: How does avg glucose translate to a1c (not mathematically - eg, is a one off treat meal going to raise it? Once every three months? Monthly? Bimonthly?)? Once RBCs are glycated, they stay that way - so in theory a ‘treat’ close to an hba1c could actually raise it even though you’re otherwise in the green?
My understanding is the HbA1c test roughly reflects average blood glucose over a 3 month period, but in reality, so people turn over red blood cells more rapidly/slowly than others.
It is recognised that any HbA1c score will be influced more by the couple of week, immediately prior to the test, that the period further back. So, I would suggest if some form of treat is desired, then after the test will be less likely to influece the result than just before. Of course, that said, a single episode or even a couple of episodes is unlikely to materially change a result.
Again, my understanding is once glycated a red blood cell remains in that state until it expires and is replaced be a brabd spanking new cell.
Reply: I think this where I start to get confused - I know that the BG tests and the HbA1c tests are looking at ever so slightly different things (the HbA1c is sort of a shorthand and we call it an average, but it isn't, really, nor does it reflect what's actually happening underneath as someone who sits around a 6 or 7 all the time could have the same result as someone who vacillates wildly but still averages out at 6-7). Personally the current question mark is why my meter was telling me much, much lower than my recent HbA1c (even allowing for missing peaks and such), and I'm trying to figure out why/how that came about. (Again, see Libre thing below.)
Q: General ‘other’ impacts on BG
Why does exercise raise BG in general that day but the next day is lower? (Might just be me.)
A: In my own case, exercise can have a variable impact on my blood sugars. Gentle exercise, like a decent stroll will lower my numbers and sometimes quite dramatically (depending on the starting point), whereas vigorous exercise will raise my blood sugars for a period, then they will drop for a time. That is usually attributed to your liver releasing stored glucose to help fuel the exercise, then afterwards, replenishing it's stores again, explaining the lower post-exercise numbers and sometimes for a period.
Reply - I think someone further up has mentioned something similar. I have noticed a 10 min pace about the flat will lower things fairly significantly, but just my commute home will not drop me anywhere near so much. It feels backwards, but if it's about my liver being a bit too helpful on a long, load-bearing walk, then that explains things.
Q: If stress plays a part (adrenaline -> glucose released for fight/flight), then surely mental health is paramount? Why is is left behind and food focussed on?
A: Stress does indeed play a part in blood glucose numbers, and for me, sustained stress is one thing I can be assured will notch me up. Fortunately, my life isn't generally too stressful.
Your question on focus; there is no doubt mental health is very important - overall, not just for blood glucose management, but in T2, there is little question that, certainly initially, if we are looking to manage our condition meds-free, or with minimal medications, then the stand-out tool in that is what enters our digestive system.
Reply: Absolutely. Stress impacts me massively, and unfortunately my life is irritatingly stressful (almost certainly the cause of the high test in January!), with no likely let up. It's a bit concerning that I've mentioned this to my GP multiple times but they seem uninterested in shifting my SSRI dosage to help out a bit.
Q: Other:
Why do people say (very?) low carb makes insulin resistance worse?
A; Very low carb can induce a state called physiological insulin resistance which is a bit different to the more standard insuling resistance. For those who experience it, it is often (I'm tempted to go usually, but will be conservate here) possible to reset this by breaking the routine with a higher, or for some and even lower carb day or two. By higher carb, I don't mean full on chips, pizza and doughnuts, I just mean a nudge up in the carb numbers.
There is quite a bit written about physiological insulin resistance which is readily findable, via DrGoogle.
Reply: I'll have to look this up, thanks!
Q: My husband has kindly offered his own fingers for pricking and he’s always within .2 of me at the same time after the same meal. Not diabetic as far as we know, and even if he was I’d expect less similar measurements. What’s happening there?
A: That's impossible to answer, without knowing more about those numbers and what is consumed prior to them being taken. [Reply - yeah, fair, I forgot to test him pre-meal. Rookie mistake!]
It might also be useful for your husband to have an A1c test at some point, just to ensure he's in good shape.
[Reply - yeah, I'm tempted. Convincing him it's worthwhile might take a while.]
0.2 is pretty close though, and I doubt any two T2s strictly shadow another's readings - especially in the early-ish period.
You clearly are curious about all of this, and I see that as being a good thing. For me, understanding and acceptance go hand-in-hand. If you haven't already, it might be worthwhile you taking up Abbott's offer of a trial Libre sensor.
Each sensor lasts 2 weeks and broadly track your blood glucose 24/7. I say broadly because it measures sugas in interstitial fluids, not blood. Broadly speaking, a Libre reading reflects a blood glucose reading of 10/15 minutes earlier, but it is a great tool to see what's actually going on. What peaks and troughs are and how long glucose actually remains elevated after any given eating or drinking episode.
Reply: So this is a complicated thing. I'm super curious about what's affecting my body and how, and I know that the Libre offer would hopefully be helpful (and also maybe help make sense of why my recent test came back higher than expected - might be something wild's happening while I'm asleep!). However, I'm a little reticent to try it for two reasons.
The first is I have a super fun skin condition called urticarial vasculitis, which also has some pressure urticaria/angiodema elements to it. I have a horrible feeling that having a filament in my skin/something stuck to me will cause a flareup (yes, sometimes even plasters cause a problem). It may well be fine, as the UV has been in remission for a while now, but I'm always keen not to poke the bear, so to speak. I also wonder how the irritation might impact the readings - we're talking a LOT of local inflammation.
The second is silly but - it's visible. I'm not afraid of getting my arms out, wobbles or no - and I'm not quite there with 'outing' myself as diabetic with people outside of close friends/family yet (particularly as a teacher!). That said, given the Zoe stuff and that loads of people are using CGMs for non-diabetic reasons now, it may not be so obvious.
PerSpinasAdAstra
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On the 1 hour vs 2 hours test, and the recommended thresholds - the two hour recommendations are an attempt to define what might be a 'harmful' meal - one that pushes up BG too high for two long. Akin to smoking a cigarette, smoking one isn't going to do much to you, smoking a thousand is unlikely to do very significant harm, but it's not impossible, while smoking after every meal every day for the rest of your life is a bad idea. Nobody actually knows what kind of a rise and duration counts as a 'cigarette', if that makes sense. Whether a rise of 2mmol/L, 2.5, or 3 - two hours after eating, or trying to stay below 8 mmol/L or 8.5 at the two hour mark, different thresholds are recommended by different people in different places and some people adopt a more conservative approach, while others are okay with a more relaxed one. As regards how that impacts HbA1c - it's all about averages. 'Area under the curve' after eating is probably the best approximation of impact on HbA1c due to diet. A single treat in a month would be a tiny blip in HbA1c terms, given all the hours of lower BG levels throughout the day and while asleep. That isn't to say a treat absolutely won't do a tiny smidge of harm though - I won't be feasting on pizza any time soon, even as an experiment. Well, maybe on my birthday 😉
The most conservative approach I've seen someone adopt was using the 1 hour test to gauge the height of the 'spike' and trying to keep that below 8 mmol/L. Many meals will spike at around the 1 hour mark, though certainly not all. That person was going by an amateur guide to BG testing written in the late 90s. This is the kind of rise typically seen in a 100% healthy person eating a healthy diet. **EDIT - The account of the person who took that conservative approach is in the replies to this post on Reddit - Link - Username: alan_s - 22 years with a stable HbA1c (in the prediabetic range) after initial big weight loss. No diabetic complications. Very Impressive.** Nobody knows how far a person has to go above that level regularly to see some kind of health impact from it. The best single resource I've found on what healthy BG levels look like is in this opinion piece written by a consultant cardiologist, though I would stress, this is opinion, not established fact of any kind - Link Trying to emulate that as a diabetic is probably unrealistic for most, and going to that extreme of BG control may not provide any benefit at all over a more relaxed approach. Nobody knows.
As regards exercise - 'hard work' seems to raise BG levels, while moderate exercise seems to lower them, with fitness perhaps being the deciding factor as to what counts as hard work. If the exercise does not cause elevated levels of adrenaline or cortisol, and if the exercise occurs at a time when BG levels are elevated (like after eating), BG levels should go down. Moderate exercise at times when you are already at your 'baseline', at your fasting levels or close to them, will have very little observable impact in that moment. It will however reduce insulin resistance a little for maybe 24 to 48 hours afterwards and so have a lasting effect. At the present time, a long brisk walk after eating always lowers BG after eating in my case. When I was diagnosed though I was obese and extremely unfit, and even long walks several days in a row caused pain and even (very) minor injury. I wasn't testing at that time, though perhaps those early walks might have been 'hard work' and so not have lowered my BG levels the way the same exercise does now.
To illustrate the utility of the 1 and 2 hour tests, and the effect of exercise, there are some images below which I created from screenshots from my CGM when I was experimenting. Bear in mind I had lost a load of weight by the time I did this testing, and I was on medication - I'm not suggesting anyone should use these as a guide to what their own BG response might be to these meals. The 'L carb bread' is 50% lower carb bread, two slices. The bagel is white bread, average size. 'LANA Pad Prik' is a meal I had delivered from a Thai restaurant with a big portion of brown rice. You can see that the 2 hour test is highly indicative, but doesn't provide the whole story. It is however a good cheap way to compare meals with one another. Bagel definitely bad. You can also see how moderate exercise 'flattened' the spike that followed quite a high-carb meal. There are much more carbs in that rice than there are in the bagel.
I've used three CGM sensors to capture data about everything I typically eat, and I use them to guide my eating. I certainly don't intend to wear them all the time - the screenshots are enough to remind me. Based on what I've learned so far my goal is to minimize the time I spend above 8mmol/L, given that this is now achievable for me after losing the weight. The 2 hour test is a reasonable indicator of what that looks like if I want to try something new. I don't mind going above this level for a short time perhaps two or three times per week, but the rest of the time I want to keep below that level. I don't actually mind a long period of elevated blood glucose levels regularly, so long as it is below that threshold, even if that might nudge up my HbA1c a smidge. I don't personally believe that BG levels that are within the range that a 100% healthy person experiences every day are likely to be in any way harmful. I hope that helps.
The most conservative approach I've seen someone adopt was using the 1 hour test to gauge the height of the 'spike' and trying to keep that below 8 mmol/L. Many meals will spike at around the 1 hour mark, though certainly not all. That person was going by an amateur guide to BG testing written in the late 90s. This is the kind of rise typically seen in a 100% healthy person eating a healthy diet. **EDIT - The account of the person who took that conservative approach is in the replies to this post on Reddit - Link - Username: alan_s - 22 years with a stable HbA1c (in the prediabetic range) after initial big weight loss. No diabetic complications. Very Impressive.** Nobody knows how far a person has to go above that level regularly to see some kind of health impact from it. The best single resource I've found on what healthy BG levels look like is in this opinion piece written by a consultant cardiologist, though I would stress, this is opinion, not established fact of any kind - Link Trying to emulate that as a diabetic is probably unrealistic for most, and going to that extreme of BG control may not provide any benefit at all over a more relaxed approach. Nobody knows.
As regards exercise - 'hard work' seems to raise BG levels, while moderate exercise seems to lower them, with fitness perhaps being the deciding factor as to what counts as hard work. If the exercise does not cause elevated levels of adrenaline or cortisol, and if the exercise occurs at a time when BG levels are elevated (like after eating), BG levels should go down. Moderate exercise at times when you are already at your 'baseline', at your fasting levels or close to them, will have very little observable impact in that moment. It will however reduce insulin resistance a little for maybe 24 to 48 hours afterwards and so have a lasting effect. At the present time, a long brisk walk after eating always lowers BG after eating in my case. When I was diagnosed though I was obese and extremely unfit, and even long walks several days in a row caused pain and even (very) minor injury. I wasn't testing at that time, though perhaps those early walks might have been 'hard work' and so not have lowered my BG levels the way the same exercise does now.
To illustrate the utility of the 1 and 2 hour tests, and the effect of exercise, there are some images below which I created from screenshots from my CGM when I was experimenting. Bear in mind I had lost a load of weight by the time I did this testing, and I was on medication - I'm not suggesting anyone should use these as a guide to what their own BG response might be to these meals. The 'L carb bread' is 50% lower carb bread, two slices. The bagel is white bread, average size. 'LANA Pad Prik' is a meal I had delivered from a Thai restaurant with a big portion of brown rice. You can see that the 2 hour test is highly indicative, but doesn't provide the whole story. It is however a good cheap way to compare meals with one another. Bagel definitely bad. You can also see how moderate exercise 'flattened' the spike that followed quite a high-carb meal. There are much more carbs in that rice than there are in the bagel.
I've used three CGM sensors to capture data about everything I typically eat, and I use them to guide my eating. I certainly don't intend to wear them all the time - the screenshots are enough to remind me. Based on what I've learned so far my goal is to minimize the time I spend above 8mmol/L, given that this is now achievable for me after losing the weight. The 2 hour test is a reasonable indicator of what that looks like if I want to try something new. I don't mind going above this level for a short time perhaps two or three times per week, but the rest of the time I want to keep below that level. I don't actually mind a long period of elevated blood glucose levels regularly, so long as it is below that threshold, even if that might nudge up my HbA1c a smidge. I don't personally believe that BG levels that are within the range that a 100% healthy person experiences every day are likely to be in any way harmful. I hope that helps.
Last edited:
AndBreathe
Well-Known Member
- Relationship to Diabetes
- Type 2
In terms of why your HbA1c was higher than expected; it is likely you are missing lots of peaks, and if you are frequently stressed, you may have plenty cortisol in play. Honestly, the Libre would likely be such a window for you.
In terms of allergies and sensitivity; I can't have anything to do with Elastoplast; even for the shortest while, but the Libre is fine on me. I don't even have a ring when it comes off, never mind the molten mess I could expect fro a good old-style plaster.
Initially, when launched, the Libre had a few challenges with folks reacting, but they seem to have worked hard on the adhesive side of things to make it much more acceptable. That said, for those with issues there are sprays that can be applied to create a barrier between the skin and sensor. I haven't used them, or looked into it too much, simply because selfishly, I didn't have to.
In terms of visibility; whilst the Libre literature states to apply on the back of the upper arm, I have applied then in all manner of places, with mixed success. One of the most consistently successful is on my upper, outer chest, where it is under the top of my bra cup, where it joins the strap. I tried that initially when I was going to be in swimwear a lot for a period. Perfect, and no additional white/pale lines.
I have also used tummy and very much lower tummy, although the latter was a filled with a bit of jeopardy when pulling down jeans quickly. I don't bother there any more.
Obviously, only you can decide how you move forward on this, but the freebie trial really is worth considering. Two weeks would give you an insight you can never achieve stabbing your fingers, and if you choose, as I did nearer the early days to wear a sensor every couple of months, the financial hit isn't all that hard. Finally, being a free trial, if you feel it all going horrible wrong, you can just take it off and throw it away in the "Be gone and don't come back bucket".
Diabetes isn't a condition that runs to programme - especially not in the early days. The harsh reality is we can learn a lot from others, but really we need to learn what works for ourselves.
Edited to add a conversion too for finger prick/A1cs: https://www.diabetes.co.uk/forum/threads/hba1c-conversion-table.174043/
This is wonderfully useful - thanks so much! The graphs are particularly telling, though interesting the one with the Pad comes back up a bit after the exercise. Wonder what's happening there - the glucose continuing to move into your system while digesting, but you've rejigged your 'starting point' as it were by exercising so the peak isn't so high and it can't *get* high? (I ask this because while it seems obviously the case, I want to check my logic!)
The cigarette metaphor is helpful as well. I've read similar things elsewhere, but I think I need to keep reminding myself that this is one of the unknowns of diabetes - we know elevated levels a LOT are bad, we know that keeping BG in certain ranges minimises that damage, but we don't know where the line is drawn, even if there IS one (I suspect that is likely genetic). I think to some extent it seems remarkable to me that diabetes is one of the most researched conditions, and actually one of the earliest described, and yet we know so very little about how it works (yes, I know better as an academic and someone with a hefty science background, but it still boggles my mind!). It's probably why I read things from people talking about metabolically normal people spiking to 10 or 12 as 'normal' and my eyebrow raises. But this goes back to one of my questions about the core of what we're trying to do here as Type 2s (Type 1 is of course very different) - presumably help our bodies clear the glucose better, since they've lost the ability to do it efficiently, but as someone's said above, the jury's out here on exactly what's the most useful thing to do and what we're actually impacting.
For exercise, totally see what you're saying. I've always been fit if fat, but I can tell my cardiovascular health has improved dramatically even then. It's only when I'm lugging *loads* of groceries/been out for ages (2+ hours)/done something stressful as well (eg be at work) when exercise doesn't seem to do as much/anything. A gentle walk (even a 10 minute pace back and forth in my flat) seems to help dip my BG a bit after a meal - something I've had to add to my routine at the moment as my husband's home at the moment and we have an 'I cook, he cleans' set up, where I can chill out after dinner on the sofa. This isn't something I can do most of the year, and gentle bustling about in the kitchen/clearing up/etc. seems to impact my BG as much as a short toddle, based on my BG readings from similar meals when he's here and when he isn't. (Nothing exceptionally weird here - we just teach at different unis and are on opposite sides of the country - a remarkably common feature of the HE set up in the UK - so we are only in the same place during holidays/leave time.)
Thanks a lot for this. I am definitely going to do a free trial, maybe to use before the semester starts at the end of September, just to get a baseline. Then maybe I'll self fund another for sensor later in the academic year, just see what changes (if anything). Next year should be marginally less stressful in terms of known variables than the last couple, but it's the unknown stuff that really gets my adrenaline going... You're almost certainly right about stress impacting things - this has been my suspicion since day 1, given how high things were back in January and the near-sudden onset of anything like a diabetic symptom. I doubt very much my employers will be interested in doing anything to help alleviate stress with clear impacts on my long-term physical well-being, though.
Or - I would, but the Abbot website is refusing to send me a phone confirmation code. I've emailed to see what's up...
I think longer sleeves/cardigan season will minimise my 'outing' issue... hopefully!
I've been using this converter - https://www.hba1cnet.com/hba1c-calculator/ . Provides American numbers as well, which are useful when talking to family about it (my sister works in healthcare, so she's been especially interested in my results - especially since she has a high likelihood of developing T2 now too (thanks mom and dad for never once mentioning to us that it ran in the family) - and it's just easiest to have the whole calculator there).
(Edited to move paragraphs around in a more logical manner.)
PerSpinasAdAstra
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As regards why BG rises again after the exercise during the LANA meal, I believe you're correct. Digestion is still ongoing. The same pattern occurs when I eat a test meal with a lot of slowly-digested carbs (wholegrain), or if there's a lot of fat in the meal (kebabs with pitta bread for example). My theory is that while I'm walking I'm burning off as much or more glucose than is entering the bloodstream from the intestine, keeping things steady or bringing levels down. When I stop walking, if there is still a significant amount of carbs left to be digested, levels rise again for a while. The pattern with rapidly digested carbs (like the bagel) is different - A walk beginning 30 minutes after eating is less effective at pushing levels downward, they often flatten but don't fall, but if I start walking at around 50 to 60 minutes after eating such a meal the exercise rapidly pushes levels down and they stay down after I finish my walk. I think it's about rate of digestion, how much carbs there are to be digested in total, and the timing and duration of the exercise. I don't indulge in a meal with higher carbs than usual unless I know I can walk afterward, and I try to time the walk to coincide with the timing of the spike that meal typically produces. The more carbs in the meal the longer I walk for. Trying to stub out the cigarette 😉
It all boggles my mind too with what little is known. The fact that the full implications of weight loss were not known until Diabetes UK funded Roy Taylor's research was shocking to me. The first 'clinical trial' of weight loss, for a disease that is very strongly associated with being overweight or obese. What if they hadn't spent that money, and Taylor never got his funding? It is what it is though I suppose. The research money often goes where it is most likely to yield a return - newer, better medications, better protocols for prescribing those medications, that kind of thing. Gotta work with the tools we have I suppose.