Morning exercise, insulin & breakfast

How should I approach morning exercise?

If I exercise in the morning, it’s usually a 1-2 hour walk between breakfast and lunch. For that type of exercise, I reduce my insulin at breakfast and leave the house about an hour after injecting. I found that going for a walk right after injecting and eating has led to wicked lows, then stubborn highs after the carbs kick in.

Today I did about 30 minutes of yoga/pilates at home before starting work and I wasn’t sure how to approach it.

Is it better to…

  • inject before exercising (and exercise during my usual 30-minute pre-bolus time)
  • inject, eat my breakfast and then exercise
  • exercise first, then inject and eat (with or without my usual 30-minute pre-bolus)

I was holding steady around 100mg/dL (and 100% in range between 70-125 for the 24 hours leading up to my exercise :partying_face:), so I decided to try the third option - exercising with no IOB and before eating.

Well, I rocketed up to 200 mg/dL during my 30 minute exercise and just after. :face_with_peeking_eye:

I saw my blood sugar going up as I exercised, but I decided to see just how far it would go. I did not expect it to go to 200! :grimacing: I rarely go up to 200.

I was pretty hungry after exercising, so I didn’t my usual 30-minute pre-bolus, I just ate straightaway. I didn’t notice a further rise from the reduced pre-bolus.

To make things even more fun, my CGM ended shortly after exercising but my blood sugar seems to have leveled off around 200mg/dL. Or at least I was still around 200 an hour later when the new sensor finished its activation period. But who knows what really happened in that hour.

I usually get a tiny FOTF bump (maybe 15mg/dL), but that comes down quickly, so this wasn’t FOTF.

So how should I handle early morning at-home exercise?

  • Should I exercise after injecting, but before eating?
  • After injecting and eating?
  • If after injecting, should I wait at all?
  • If I let my blood sugar rise and inject after, should I base my dose on the pre-exercise blood sugar or post-exercise blood sugar? Today, I split the difference and I’m currently 105 and steady (4 hours after exercising).

I’m on MDI and I split my basal between bedtime and breakfast.

I’m happy to give a few different approaches a try over the next few weeks, but would appreciate some wise words to guide me.


How is that exercise in terms of intensity? Like on a scale of 1-10, with 1 being taking a nap with a kitten on a rainy day, and 10 being chased by a lion through a field of landmines.

What you should do depends on the type of exercise and the intensity.

Exercise can definitely amplify that if your body sense that it needs fuel for the exercise.


I’d say it’s about a 5-6 at the moment. It’s not super strenuous, but it is a new exercise routine for me so it’ll take a while to get into the groove.

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Some of this might be stuff you already know. Or it might be stuff you are not familiar with.

You already know about how your BG rises when you wake up. That’s a very common thing. Your body needs a little more energy when going from being asleep to being awake. Your liver puts out a little glucose. And there are hormones that are activated when you wake up. It’s just the stuff that wakes a person up, it’s all normal natural stuff.

But what about exercise? Do you know how your body fuels exercise?

The overly simple way of explaining it is that the higher the intensity, the more it relies on glucose. The lower the intensity, the more it relies on fat metabolism.

So being at a 5 or 6 means your body is needing to provide glucose for you to do the work. And it can use stored glucose in your muscles (called glycogen), but it can also use stored glucose that your liver puts out.

Stored glucose in your muscles will not raise your BG. But the stored glucose your liver puts out will raise your BG.


I’m a bit hesitant in chiming in as a type 2 on a pump.Here’s my experience with morning exercise. I bolus for breakfast as normal. My routine exercise is cycling around 30 minutes after I finish eating.

Today I did one hour, about 35 minutes in BG started dropping. It hit 69mg/dl and then rose to 71 by the end. I did have the pump in activity mode. Within 20 minutes BG was up to 90.

This is a usual thing on the stationary bike. When I ride on the road is different. I think I work harder. This makes a difference. Staying in heart rate zone 2-3 tends to steadily lower BG over time. HR zones 4-5 tends to increase it while doing it.


Great observation right there. :+1:


What kind of practice did you do today? As a yoga teacher, I had to lower my basal and have no IOB for a flow class whereas for a core/strengthening class, I needed more insulin before I started or my BG would rise. :woman_in_lotus_position:t3:


So everyone here is saying the exact same thing with their own experience to back it up.

Does all of that make sense?


Thanks for this Eric. It’s really helpful.

Most of the exercise I’ve done since diagnosis has been walking/hiking, so I was applying what I do for walks to what I did yesterday. But since it’s a totally different type of exercise, I need to rethink my approach.

Is there a way of ‘forcing’ my body to use glucose stored in muscles rather than from my liver, or is that something completely out of my control?

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Cheers Carlos!

Interesting that the different types of bike riding with either raise or lower your BG.

I’ve got a lot to think about!

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Hmmm… I’m not sure how to classify them.

Here are the exercise videos I did today:

Those came to about 50 minutes.

Yesterday I did similar exercises, but they only came to about half an hour.


I tried a different approach today.

After my massive rise yesterday :grimacing:, I’m not worried about going low (I would be if it was a walk with fresh insulin on board, but I see now that this exercise affects me differently).

Today I pre-bolused my usual 30 minutes, ate toast (I usual have a bit of toast as my first breakfast, then fruit as a second breakfast a few hours later once my blood sugar starts going down), then 15 minutes later (45 minutes after injecting) I started my exercises. I did about 50 minutes today and I held steady between 110 and 140 (my exercise period is the purple box). :trophy:

After I finished, my blood sugar dropped a bit and got two pears instead of the one pear I’d planned. :pear: :pear: I guess that makes up for yesterday - my rise led to so much insulin resistance that I didn’t get my second breakfast at all yesterday. :sweat_smile:

I’d usually go low if I went for a walk within an hour of injecting, but I can see that these exercises affect me differently. I guess the ‘fresh’ insulin is supercharged by the exercise and wants to bring down my blood sugar, but then this type of exercise is trying to increase my blood sugar, so they balance each other out.

I’ll try the same approach tomorrow, but maybe with 4 units instead of 5 to see how it goes.

Thanks for all your help, everyone! I was really worried about going low exercising with fresh insulin on board, but now I can see that worry was unfounded. :laughing:

Hopefully tomorrow brings me as much success as today did.


Yes and no.

Your body will use muscle glycogen for the exercise, and in the case of a non-diabetic it will use liver glycogen to maintain blood sugar level.

It will also put out liver glycogen to provide additional fuel if the intensity becomes higher. (And in the case of the non-diabetic, this is also matched by the release of insulin.)

If you can imagine getting chased by a lion, your body would want to make sure you had enough fuel to escape! What do you think would happen to your BG?!

So in the case of exercise, your BG rises when your body detects that it is a sufficient stress level. But if you were to do the same exact exercise over and over, what do you think would happen? Over time, the exercise becomes commonplace. It is no longer a stress factor.

So the short answer is that if you do the same exact workout over and over, your body will no longer react with the same BG rise. As your fitness improves, the same workout becomes easier. And it is no longer much of a stress. Your body becomes used to it.

But of course we generally increase our exercise intensity over time as we get better and more fit. We do harder and longer workouts. So we might not see the difference in BG because the new (harder) workouts will create a BG response just like the older (and now easier) workouts used to do.

Does all of that make sense?

BTW, I like to see that big BG spike during a workout (as long as it wasn’t from eating something). It is a sign that I am working hard. Maybe that is a more helpful way to look at it.



So as I get used to being chased by a lion, my spike won’t be as high. Then as I increase intensity, it’s like adding a second lion. As I get used to being able to outrun them both, my spike levels off again and it’s time to add another lion. :lion:

So it sounds like that spike yesterday was from a combination of (a) no insulin and (b) the first day of a new routine. But the huge spike meant that the insulin was working against some resistance and I wasn’t able to eat all the fruit I’d bolused for.

Today’s tiny spike was because of the insulin and I definitely felt better. I wasn’t on an empty stomach and I was able to eat my normal bolused-for breakfast, plus double my second breakfast. But even with the extra fruit, I still went a bit low before lunch, so I’ll try 4 units instead of 5 tomorrow. I might see a bit more a spike than I did today, but hopefully it won’t be followed by lows.


Some poses demand a lot of the core muscles, such as the plank series, boat pose, or hand/knee balancing, because you are working to counter gravity. Standing pose sequences, such as sun salutations, can be done relatively fast or slow to focus more on aerobic fitness, strengthening, stretching, or a combination thereof.


@Finn, the following image is of two workouts I did yesterday, one cycling and the other resistance with a recovery period between. This gives a good illustration of how different workout types can affect BG in different ways.


Thanks Carlos.

I’m starting to notice these trends and realise I can’t apply my walking insulin strategy to other types of exercise.

Yesterday morning I did 4 units with a 30 minute pre-bolus, had my usual breakfast, did 30 minutes of HIIT staying beautifully between 100-135, then had two pears for my second breakfast (rather than my usual one) and flatlined around 110.

I’m trying the same today, except different exercises and it’s Saturday, so we’ll be walking around the Saturday fruit and veg market an hour or so after finishing my exercises, then hopefully a walk before lunch.

The last few weeks I’ve really been paying attention to what I eat (I realised I was getting a lot of calories from cheese and houmous :grimacing:) and, paired with exercise, I’ve reduced my basal from 5 units morning/4 units evening, to 4 morning/3 evening. I might need to reduce my evening basal by a unit once again since I’m still going low most nights and needing a half a granola bar (about 7-8g carbs) a few hours after going to sleep.




Today was pretty much the same as yesterday - 4 units, 30 minute pre-bolus, toast for first breakfast, 50 minutes pilates/yoga, then a pear for second breakfast, a walk around the market (just a few minutes from our flat) and then to the supermarkets (about 5-10 minute walk away).

During the workout, I peaked at 125, then went a bit low a few times before and after lunch despite having extra fruit, Müsli cookies and glucose tabs.

I’ve reduced both my morning basal and my breakfast bolus to compensate for the morning exercise, so it’s possible that I went (and stayed) lower today because I’m ovulating - I tend to run a bit low during this time in my period. Or maybe I need to reduce my basal or bolus further.

Tomorrow I’ll try 3 units bolus at breakfast and eventually I’ll start to notice if my pilates/yoga routine affects me differently than more intense exercise, like HIIT.


Agree, for breakfast, I usually eat a poached egg with fish or porridge and then go to the forest near the house for a bike ride. I used to drink only coffee in the morning and immediately went to work or did household chores, but I felt worse than now. My neighbor first let me ride her bike, then I already bought mine for riding in the woods. if you are looking for something for yourself then I advise Hiland. Let’s keep our health in good condition.

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