Exercise if BG is higher than 12mmol/L

[Proud to be erratic]

A comment earlier this afternoon in the Newbies thread by @everydayupsanddowns was made ... "best to not exercise if higher than 12mmol/L" or very similar.

This caught my attention since if I'd previously been told that it was a snippet of info that my brain hadn't retained (not unusual these days). But also how contrary this could be to advice we frequently offer about getting active briefly after a meal or using activity (= specific exercise(?) - that boundary is necessarily murky) deliberately to bring a high BG down.

I looked to see what DUK had to say on this subject and that was informative (yet also attracted a further pedantic niggle in my mind):

Does exercise lower blood sugar levels?

Although exercise can lower blood glucose (sugar) levels, different types of physical activity can affect your blood sugar levels in different ways. You might find your blood sugar levels going up or down — and at different rates — depending on the type of physical activity you’re doing, how...

www.diabetes.org.uk

Guidelines on blood sugar levels when exercising

These recommendations are only guidance, and your individual experience when exercising may differ. If you are using an insulin pump the guidance will be different. You should speak to your healthcare team about what's best for you.​

​

What should blood sugar levels be before exercising?

Before starting exercise your blood sugars should ideally be between around 5.6 -12mmol/l. But this is a guide and may vary for you individually depending on the type of medication you take and the type of exercise you are doing. If you are taking up a new activity it is useful to talk to your healthcare team and agree a plan for managing your blood sugars during exercise. ​

​

This immediately triggered a lateral thought: why "around" the quite specific number of 5.6, why not "around 5 or 6"? Is this why Abbott have the rather silly low alert limit at 5.6 or DUK taking Abbott as the lead authority? Or is there some better explanation for 5.6?

My lateral thoughts got deeper as I read on and looked at the table that followed "Am I ready to start exercising? Check our recommendations below". This table has 4 categories (rows): "less than 4mmol/L; 4-7 mmol/L; 7-13 mmol/L; and above 13mmol".

Now, ignoring my pedantic comment should 12 be 13 or 13 be 12 in this bit of DUK narrative, and accepting somewhere in the low teens, HOW does such a number sit when balanced against the general advice to use activity / mild formal exercise to help nudge one's BG down. More fundamentally is no activity when above 13 underpinned by solid medical rationale?

Yes, I can sit quietly and take a corrective bolus when I'm really too high, but invariably that is not sufficient - unless I increase (strengthen) my correction ratio by a lot. I don't like doing that because its putting me on one end of the high /low roller coaster. I feel happier going for a long walk and much safer than risking getting on the roller coaster.

If I was not insulin dependent, what then would be a possible response if, say, in my high teens and ketones were OK?

I would be delighted to get a bit more clarity on this topic. Meanwhile I will continue to do what I think is OK for me, but hold back (for now) from suggesting my thoughts on this topic in responses I might make to posts from others in different threads!

 

[Lucyr]

You’re way overthinking it. If you’re high and want a walk then go for it and keep an eye on your bg. If you’re high and want to do intense exercise that raises your bg, do a correction first.

 

[rebrascora]

I think there is a difference between going for a walk when your levels are high to help bring them down, rather than doing intensive exercise when your levels are high, which puts your body under increased strain than just the exercise itself does, so potentially risking a cardiovascular event. We know that high BG and high BP go together so not a good idea to add extra strain to your body in those circumstance, but an hour's walk, unless you are very unfit, is not going to increase the strain on your system and will most likely reduce it, so I think it very much depends on the type of activity/exercise you are considering when BG levels are in the teens. .

I personally generally correct above 8 (my high alarm is 8.2 because I view my job is to administer enough insulin to keep my levels in range which is what my pancreas did before it lost the ability to do so. It didn't make me get up and walk around the block. I am not saying I do not sometimes do exercise to bring my levels down but mostly I see it as my insulin's job.

 

[SimonP]

I think there is a difference between going for a walk when your levels are high to help bring them down, rather than doing intensive exercise when your levels are high, which puts your body under increased strain than just the exercise itself does, so potentially risking a cardiovascular event. We know that high BG and high BP go together so not a good idea to add extra strain to your body in those circumstance,

But where has this come from? Why do you think having high blood sugar makes such a massive difference (when you'll have high blood sugar anyway even if not exercising)? Exercising means the muscles become more insulin sensitive and they can also (eventually) use glucose without insulin, so I don't really see what the concern is. Certainly long term high blood glucose leads to cardiovascular issues, but afaiu it's not an acute problem.

I don't think there's a problem exercising with high blood glucose, aside from the potential concerns around ketone generation, which are vastly blown out of proportion for those who have basal insulin on board (i.e. don't have a pump failure which might mean no insulin on board at all).

12mmol/l is also not at all high, I will take a correction dose if I sit in the high teens for too long (while exercising), but otherwise will just ride less hard to bring it down without insulin (as taking insulin will cause a crash, which is bad when a long way from home with limited food to deal with it, and probably not really feeling like eating too much either.) It depends on what the exercise is of course and how far away from home (and food and the ability to stop) you are - if I'm playing badminton (and not 100km and 5h away from home) I'll take a small correction if I sit in the low teens for too long, but otherwise it will come down on its own.

My thoughts here, with a link to the consensus statement paper which the recommendations probably came from. They had to choose a number, it's fairly arbitrary what it is, and you'll find that with experience people choose different numbers based on how their bodies work, and which exercise they are going to undertake: https://forum.diabetes.org.uk/board...a-consensus-statement-from-the-lancet.108996/

 

[dannybgoode]

I don't think there's a problem exercising with high blood glucose, aside from the potential concerns around ketone generation

I agree and I think it somewhat depends on the length of time someone has had high BG.

So, if I've been spending the day in the 6-8 range, then eat something nice and carbie, BG spikes to 14 and I go for a run, I can't see any reason this would be an issue.

If though you're newly diagnosed and it's clear that your BG has been very elevated for a period of time then there is a chance your blood is thicker and your CV system inset strain and it may be sensible to ease into things slowly whilst BG comes down.

That said, my Hba1c was 121 and my on the day BG 27+ and I've been running throughout the period it was building and never knew and never felt any effects. Not saying that's sensible or not but I didn't know so didn't stop!

I think as well if you're BG is not normally well controlled and you run high for a lot of the time and/or suffer hypos then it's sensible to speak to your DSN or GP before going in hard.

 

[Proud to be erratic]

Thanks for these comments. I'm still contemplating, chewing the cud so to speak. I was going to say ruminating - but just checked if that was the right word; it isn't.

 

[SimonP]

From a very quick scan of the available journal papers turned up by Google (I know, hardly a 4* paper review!) it appears that viscosity may or may not be related to diabetes and instantaneous blood glucose (quite often the papers are talking about T2, though there are some talking about T1 specifically.)

E.g.
here well controlled T1 patients have a lower blood viscosity than poorly controlled and non-diabetic control patients: https://www.sciencedirect.com/science/article/pii/016882279601279X

here 3 groups of patients: controls and two groups of T2 patients with different BG levels were compared and those with higher BG were found to have higher blood viscosity, though if you look at the table it's interesting to see that the middle group (T2 with the lower BG of the two groupings) appear to have the highest viscosity: https://diabetesjournals.org/care/a...-Viscosity-in-Subjects-With-Normoglycemia-and

It would be useful to find a metastudy to see what high quality papers have to say for themselves, but from a quick glance it doesn't seem that there's a clear consensus (aside from the fact that T2 diabetics tend to have higher blood viscosities).

It also appeared that the ranges within groups overlap, which would indicate that long term high blood glucose may well change viscosity, but that there are differences between people which have a potentially larger effect - I don't know how well the studies controlled for things like temperature (changing blood flow to the peripheral tissues and therefore potentially overall blood volume/viscosity effects) and hydration level.

It would also be interesting to find a paper looking at the transient BG change effects and whether osmality differences drive viscosity changes and if so how fast for transient (rather than long term) BG changes.

 

[dannybgoode]

I would add, if I were going for a run starting at a BG of 12 and took a correction first then ran, my BG would plummet quicker than one of Monty Python's flying sheep. It would be a bad idea and I'd then just be chasing the cliff edge with way more carbs than I'd usually take.

This is yesterday's graph during a run. Started at 10, rose to 12 so didn't fuel, towards the end started dropping and ended up 5.4 just before I ate. Now imagine that with 2 or 3Us of NR bubbling around!

Note also though I'm very fit so that has a mitigating factor as well. I wouldn't suggest everyone jumps straight into marathon training for example...

 

[SimonP]

Likewise, if I'm riding for less than 2h and it's first thing I need to take a (full) correction for FotF, if it's past mid-morning I'll fall rapidly after say an hour if I take a pre-ride correction. This is acceptable if I'm mid teens and don't expect to ride for too long (though even here I tend to take a smaller-than-usual correction, accepting that I will drop more slowly initially, but once insulin sensitivity kicks in I'll be in roughly the right place - need to eat, but not too much). If I'm in the same situation and have a 4 or 5h ride still to go there's no point in correcting (unless I'm really high - high teens) as I'll end up needing to eat continuously once the insulin becomes effective/muscle insulin sensitivity increases, which can be very hard to do.

That's not to say that it's necessarily a good thing, but it's just the thing that works if one can't have a perfect BG pre-exercise (no-one is perfect, certainly not me!) I should also add that I've done this for 30-odd years (in the days of two injections a day there wasn't much opportunity to tweak dosage without other deleterious effects at other times of the day so eating lots pre-rugby/PE/etc. to generate a spike was the way to make it all work) and it seems to have been ok thus far.

Back when bolus insulin wasn't a thing, and I mixed short and long acting for two-a-day injections, if I were running high a walk would be the best medicine - taking more units which would act over the next 5h wasn't effective unless ill/having made a mistake in eating, but walking does provide the best/easiest BG reduction bang for your buck (mowing the lawn is good too - but I didn't often do that as a child!)

 

[Robin]

I think there is a difference between going for a walk when your levels are high to help bring them down, rather than doing intensive exercise when your levels are high, which puts your body under increased strain than just the exercise itself does, so potentially risking a cardiovascular event. We know that high BG and high BP go together so not a good idea to add extra strain to your body in those circumstance, but an hour's walk, unless you are very unfit, is not going to increase the strain on your system and will most likely reduce it, so I think it very much depends on the type of activity/exercise you are considering when BG levels are in the teens. .

I personally generally correct above 8 (my high alarm is 8.2 because I view my job is to administer enough insulin to keep my levels in range which is what my pancreas did before it lost the ability to do so. It didn't make me get up and walk around the block. I am not saying I do not sometimes do exercise to bring my levels down but mostly I see it as my insulin's job.

I relied on the advice from Runsweet when I was learning how to manage my levels while exercising

Diabetes and Sport

A site for people with diabetes with a focus on sport, providing information on diabetes and sport as well as other diabetic issues.

www.runsweet.com

They mention the times when your levels will rise rather than fall, I’ve always assumed the advice not to exercise with already high BGs, is that you run the risk of them going even higher.
They mention anaerobic exercise, and also, exercise where an element of competition, or nerves plays a part. I know if I ride my horse, a nice gentle hack with plenty of trotting will lower my levels. A serious one to one lesson with an instructor over jumps or cross country fences will sent it skywards, as the fear factor kicks in. (the fear being, your horse decides it doesn’t like the jump, stops suddenly, and you end up flying over it solo)

I also came across a link to the Runsweet site on the Bertie online course I did a few years back, in the section on hypos. Runsweet reckoned that in an emergency, if you were out for a walk/run and you ran out of hypo treatments, you could raise your blood glucose levels by putting in a sharp sprint. I tried it once, we were just short of the tearoom on a long walk on a hot day, and I’d been having to top up with jelly babies all the way round, and had run out. Feeling myself dropping again, I sprinted up the last hill to the tea room, and staved off a hypo until I’d got cake in front of me. (there may have been adrenaline assistance, as I was panicking slightly, coupled with body stress because it was a very hot day)

 

[SimonP]

I also came across a link to the Runsweet site on the Bertie online course I did a few years back, in the section on hypos. Runsweet reckoned that in an emergency, if you were out for a walk/run and you ran out of hypo treatments, you could raise your blood glucose levels by putting in a sharp sprint. I tried it once, we were just short of the tearoom on a long walk on a hot day, and I’d been having to top up with jelly babies all the way round, and had run out. Feeling myself dropping again, I sprinted up the last hill to the tea room, and staved off a hypo until I’d got cake in front of me. (there may have been adrenaline assistance, as I was panicking slightly, coupled with body stress because it was a very hot day)

This is also in the EXTOD training materials.

I also get the same as you re nerves, setting off for a 10h ride, despite riding gently (as otherwise you don't make it at all), will result in a higher BG than a short well known one even when riding that one harder.

 

[PhoebeC]

Yeah I’ve heard 13 and I believe that’s the dafne amount.
Both me and the other person on the dafne pump course said we exercise if higher, but also play team sports and the adrenaline and excitement of matches increases BG anyway and sitting out high levels impacts more than just us. The nurse said “again” that it’s advice.
Also it’s as others have said the overall picture of your day and recent wellness which only you know.
Walking I do find is an exception to this rule, and I would go for a walk to combat a rising high, also I don’t drive so sometimes walking is my only method of transport so again what’s the alternative?
I’d probably take it easy if as others have said the high had been for a long period of time, but also if this is the case I would feel like crao and unlike exercising anyway, I’ve always been sensitive to high levels for mode than 6iah hours. I wouldn’t go to training on bad high day, but a match I would likely do what I could to get it under control and still play.