Sounds plausible! Thanks for sharing, I figured it can't only be me seeing these things. Admittedly my training hasn't been so regular recently due to house renovations, injuries etc so perhaps I just need to get a better schedule together to ameliorate these peaks.
Spikes when exercising
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LittleGreyCat
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Diet drinks - the artificial sweeteners taste vile.
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That graph is very similar to mine when I cycle in the mornings.
Possibly worth looking up Dawn Phenomenon.
When I am keeping to my eating plan I am in ketosis.
That means that my body has switched to using ketones for energy.
I cycle moderately (average 10 mph, short hills) after my morning bullet resistant coffee. That is coffee, butter, double cream.
I usually start around 10 am (in a group) and sometimes trigger the high glucose alarm on my Libre 2.
No symptoms, just the machine nagging.
My BG peaks around noon then drops rapidly back.
If you are truly keto adapted then you do not need carbohydrates.
Plenty of athletes exercise fasted and allegedly if you are in ketosis you are a little slower but never hit the wall.
From previous discussions major problems are usually when you are not in full time ketosis but try to switch in and out.
Our bodies are designed to run on ketones when carbohydrates are not available.
That is what fat stores are for.
In ketosis your body still manufactures glucose by gluco-neo-genesis and keeps your liver topped up so you are still likely to see a liver dump in the morning.
I'm not long back from a 5K run and tested just before I left and had a BG of 6.0, then tested again when I got home and it was 10.5.
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How did you feel during the run? Was it hard work?
How was the weather? Was it too hot? Windy? Rainy? Perfect weather?
Was it the same as your regular runs? Or was it longer? Or faster?
How often do you go running?
No need to answer the questions - there were kind of rhetoric.
The purpose was to suggest that if the run stressed you out in any way (out of breath, too hot, running against the wind, ...) this can affect our blood sugars.
This is illustrated with my cycling
- If I pootle along a flat tow path, chatting with my friends, my BG is unaffected.
- If I race along the country lanes for 30 minutes or more, my BG will drop
- If I slog up a steep hill on a very wet day against the rain, my BG will climb with me.
Yes this definitely chimes with my experience. If I'm running 5k or 10k then I'm generally doing it as fast as I can, or cycling making the terrain as hard as I can - I don't have a lot of time for exercise so I try to make the most out of it! In that case I am attempting to stress myself and I always see big spikes.
My question is: in and of itself, does this have negative effects, or because we're consuming the sugar, somehow this high reading can be safely ignored? I would try to avoid hitting 13 after a meal, but does this mean I should not do exercise because the same thing happens?
I'm no expert but I'm not concerned about the spikes as I expect it's just my body fueling itself. In the last month or so the only times I've really seen spikes over 10 has been after a run (and that includes 2 weeks where I was wearing a Libre2) so it does appear to be very temporary. I haven't checked before and after a cycle ride yet but might do that at the weekend and see if it's the same.
I've not done any longer runs or cycle rides since being diagnosed and then switching to a low carb diet - so it'll be interesting to see what effect (if any) that has on my endurance.
It was the first 5K I've run in about 18 months so was definitely harder than it would usually be, as I've been getting most of my exercise recently from walking my dogs)! On the other hand I'm probably 2-stone lighter than the last time I ran any distance so that should help. Strava gave the run a "tough" relative effort of 115 which gives some reflection of how running unfit I am at the moment. Back when I was reasonably running fit I'd have expected maybe a 50 or so (and even my 5K PB was only 79).
I wasn't surprised (or concerned) by BG was elevated - just interested. As I get back to some running & cycling fitness it'll be interesting to see if things change.
Just re-checked and it's back down to 6.4 (or 5.8 - depending on which of my 2 meters is more accurate) now, so don't think the spike is an issue
I'd not seen this thread before. I'm a cyclist, if I go out nice and gently (Z1/Z2 power/HR) my blood glucose will not rise immediately (or indeed at all), if I set off in more of a hurry (Z3/Z4) it will rise immediately. It generally starts to drop after 1h30 or so no matter how I'm riding unless I've really messed up my basal dose (I reduce it for rides of more than ~2h unless they are unplanned). Though today, unusually I did a fairly gentle 1h loop and it started to drop after 15min so. I probably also had the tail end of my lunch bolus on board, which may also explain it.
My general assumption is a glucose dump from the liver for anaerobic-ish levels of exercise, vs none or very little for aerobic exercise.
During a ride (after the transient stuff in the first 1h30 or so), I also clearly see rises in blood glucose associated with anaerobic activity (decent hill climbs, harder efforts to get off main roads, etc), which counteract the flat to negative trend I get from 1h30 onwards. Before that point it's hard to know what the cause is as I reduce basal and tend to eat something uncovered before I leave.
My general assumption is a glucose dump from the liver for anaerobic-ish levels of exercise, vs none or very little for aerobic exercise.
During a ride (after the transient stuff in the first 1h30 or so), I also clearly see rises in blood glucose associated with anaerobic activity (decent hill climbs, harder efforts to get off main roads, etc), which counteract the flat to negative trend I get from 1h30 onwards. Before that point it's hard to know what the cause is as I reduce basal and tend to eat something uncovered before I leave.
HSSS
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whilst the idea of carbs being essential to exercise, type 2 or not, it ignores the utilisation of fats and ketones for endurance exercise. Have a read of “the art and science of low carbohydrate performance“ by volek and phinney.
my oh is a serious life long cyclist. He is not diabetic and seriously carb loads. Yet I‘ve recorded ketones in him after a long ride (100km+) and he regularly does 3/4hr (18mph av) rides fasted without any additional fuels. Exercise has made him somewhat flexible in using carbs/ketones despite the high carb intake he has. I imagine if he ate a ketogenic diet he could cycle for days without bonking
my oh is a serious life long cyclist. He is not diabetic and seriously carb loads. Yet I‘ve recorded ketones in him after a long ride (100km+) and he regularly does 3/4hr (18mph av) rides fasted without any additional fuels. Exercise has made him somewhat flexible in using carbs/ketones despite the high carb intake he has. I imagine if he ate a ketogenic diet he could cycle for days without bonking
In the past I've never needed to fuel for either long runs (I did a half-marathon a few years back) or longish (50 to 60 miles) cycle rides and never had any issues with bonking or the like. When I get back to that it'll be interesting to see if that's still the case now I'm eating a lot less carbs.
It's amazing how far you CAN get without carbs, but I do need them for longer rides. I'm not keto though.whilst the idea of carbs being essential to exercise, type 2 or not, it ignores the utilisation of fats and ketones for endurance exercise. Have a read of “the art and science of low carbohydrate performance“ by volek and phinney.
my oh is a serious life long cyclist. He is not diabetic and seriously carb loads. Yet I‘ve recorded ketones in him after a long ride (100km+) and he regularly does 3/4hr (18mph av) rides fasted without any additional fuels. Exercise has made him somewhat flexible in using carbs/ketones despite the high carb intake he has. I imagine if he ate a ketogenic diet he could cycle for days without bonking
I never 'carb load' beforehand for cycling since it's easy to take stuff with you (less fun for running though I guess). A regular 55km circuit I do takes about 2h and I just do that fasted (I'll still end up with a spike to 10-12 though). If I'm going to be out for more than 3 hours I'll have some breakfast including some kind of oaty thing (I don't have breakfast on a non-riding day). While riding I eat carbs since they just go straight in and straight out again, I don't think there is any problem there. I have met the odd person who rides keto, but not many.
In theory you can ride forever without carbs if you stick to Z2 efforts. One ride last summer I did the first 4 hours with a couple of glucose gels, then the last 4 hours without anything (zero carb electrolyte drink only). Was a lot slower but perfectly possible.
In general I'm erring on the side of "don't worry about spikes while you're exercising".
Interesting to hear from T1 viewpoint. I am pretty bad for just forgetting to eat during long rides but the worst that will happen is I just get slower. But if you are T1 you could presumably put yourself in difficulty doing that. Could you pull back out of a low by going harder again? Presumably that mechanism only works when the liver has some glucose to dump though, you've probably rinsed it all out after 2-3 hours.
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Whether we "could" or not is immaterial.
It is advised to always correct a hypo with fast acting carbs. Otherwise, the body will become too familiar with low levels and lose hypo awareness.
I think the problem, as you say, is once you've used up all the on-board glycogen, there's nothing else to stop you going low if your basal is set too high. I must have a look back at my ride & XDrip+ data and see whether hard efforts after say 4h generate rises or not. For shorter rides I've ridden harder and avoided needing to eat the food I'd expected to need, but I expect this would taper off (along with my ability to ride hard as I go low - I have ridden the last 10km home a couple of times after running out of food with a blood sugar of iirc ~3.5, it was slow and very hard work. I'll dig the data out).
When I was fiddling with my basal doses I did a couple of 5h30+ rides without eating anything (aside from uncovered breakfast before I leave), once the initial high wore off I had a very gradual decline in blood sugar (iirc I was sitting around 10mmol/l for most of the ride), so it's certainly possible to ride unfuelled (I don't carb load either) though I did feel that performance was tapering big time after about 4h. It may just have been the hills of course, but I would prefer to be able to eat to have more energy available and not feel as drained at the end, it's just the balancing act of getting basal just right to avoid having to eat more than you can face towards the end of long rides. I am going to experiment with small bolus doses and see how that works.
This year it's more tricky as I'm running really high immediately after I leave home (even if I take some bolus with breakfast), so I can easily ride 100km without needing to eat anything, but once my blood sugar starts coming down it keeps doing so, so I do need to eat after that point to avoid going low. Theoretically I should reduce basal (to deal with the going low later), take more bolus to sort out the initial high (which is partly caused by dawn effect that I didn't previously get), though the tail of the initial bolus is quite long so stretches across quite a lot of the ride and I've not yet been brave enough to give myself significant bolus first thing and then set off on an all day ride for fear of running low and not being able to easily fix it/get home....
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Sorry if I wasn’t clear. My oh is not keto - a million miles from it. His carb loading is his normal diet. My fundamental point was ketones keep you going without glucose, long after the carbs have been used up meaning carbs are not essential. Exercising fasted regularly can enable you to be become more flexible metabolically and utilise ketones even when you don’t eat that way.
Just back from running a slow 5K and my blood sugar tested at 9.2, which is a bit lower than the 10.5 it was after my last 5K run.
When I train legs especially squats my sugar level spikes for a little while then goes down rapidly and good for few days
marty313
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I am 59, 183 cm with DM1 since 2004. I was 100 kg until 2 years ago when I developed insulin resistance on top of my DM1. I was prescribed Forxiga (daplaglifloxin) 5 mg, which helped me to lose excessive glucose via my urine, but which has been taken from the market for DM1 because of deaths due to normoglycemic ketoacidosis (!).
And I exercised on top! Since last summer I am 87 kg and my DM1 is under control again.
Since March 2022, I do triathlon. Last year triathlon sprints (3 x), this year I doubled the distance.
Only 3 weeks ago I managed to couple my CGM to my Garmin watch. But before this, I had to make sure that I don't get hypos while swimming or cycling, and my blood glucose would often be well above 15 mmol/l. With CGM I now have more control.
So I would not bother about 12.
