Walking/carbs/insulin confusion

[Andywidd]

Hi,
I was diagnosed with type 1 end of June ‘21. I’ve managed to keep my BG between 4-8mmol for the last 3 weeks or so according to my Libre app and generally feeling much more ‘normal’ for most of the day by doing this. However I’m not doing anything active having previously been very active. Im very keen to get back walking, running, weights etc but just going to try walking to start with. I’m a bit confused regarding whether I need to take insulin when I’m walking and when I’m starting to go low when walking. Today for example I walked about a mile and could feel my Bg was starting to drop a little. The reason for my confusion is that I understand (rightly or wrongly) that I need insulin to get the blood glucose into my muscles and brain etc so if I’m walking and going under 5mmol for example and eat say 10g carbs every 30mins for example while still walking will these carbs keep my BG at an acceptable level and get into my muscles to keep me walking due to my slow acting insulin and any residual fast insulin (and ‘honeymoon’ insulin) or should I inject fast insulin to get it into my muscles? Hope this makes sense? I guess I’m worried i’m eating small amounts of carbs but that these are not getting g to where they are needed. Thanks in advance for any advice. Andy

 

[Robin]

Hi Andy. I find when I’m walking that my insulin sensitivity is greatly increased, so if I need to eat some carbs on the way round, the glucose gets into my muscles just fine with my basal or residual bolus insulin. It is a case of trying and seeing, though, until you find the 'sweet spot' of how many carbs you need and how often. Sometimes I do the opposite approach, and reduce the bolus I’m having with a meal, if I know I'm going to be exercising straight afterwards, (but unless I go straight out, this risks having rising blood glucose before I start the exercise).

 

[Inka]

@Andywidd I understand what you mean. The simple answer is No. Eat what additional carbs you need to keep walking and keep your blood sugar up. Don’t take insulin with these ‘top-up’ carbs. If you go for a long walk and take lunch with you, you’ll probably find you need to inject less insulin than normal for the lunch.

You’ll always have some insulin working in the background - ie your basal, the end of your last bolus, or whatever. That and the effect of the exercise will allow you to eat the top-up carbs and use them without injecting insulin.

If you think about it, it has to work like that else you’d never be able to treat a hypo if you had to inject absolutely every time you ate.

 

[Bruce Stephens]

Sometimes I do the opposite approach, and reduce the bolus I’m having with a meal, if I know I'm going to be exercising straight afterwards

I do the same, as suggested by my dietician.

She surprised me by suggesting that on evenings when I planned to go out dancing (a couple of hours of social tango, so basically walking) I should halve the bolus for that evening meal. But she's right, and that works out about right most of the time. (And sometimes, if you do enough exercise, you may find you need to reduce that night's basal a little, too.)

Exactly what works is trial and error, but @Robin's right that insulin sensitivity increases, so just eat without extra insulin if you need to.

 

[Andywidd]

Thanks everyone for your responses. Very very helpful. I’m aiming for my first long walk tomorrow armed with jelly babies and German rye bread! (As well as regular bg checks)

 

[helli]

One common approach is to add some carbs (a bit of juice or weak squash) to your water bottle whilst doing cardio. This means you are constantly taking on carbs rather than topping them up with jelly babies when your levels fall

Something to consider for later when you get more active: you mentioned you enjoy weights. Typically, weights will increase levels. I tend to combine them with cardio so as my levels start to fall after 30 minutes on the treadmill, the weights lift my levels again.

 

[rebrascora]

The way I think about this is that my muscles store glucose. When you are not exercising, they don't need any more so the cells are resistant to taking extra glucose from the blood and insulin is needed to push the glucose into the cells. When your muscles are working and using up their stores, the cells realise that they need to top up and suck glucose out of the blood stream without the need for insulin. I find that this will often continue during the night whilst I sleep if I have been for a decent walk, so I need to reduce my evening basal insulin dose to ensure I don't hypo overnight, particularly if I do consecutive long, brisk walks over a number of days, so doo consider basal reduction once this becomes a regular regime.

Well done on your excellent control so far, by the way!

 

[Andywidd]

The way I think about this is that my muscles store glucose. When you are not exercising, they don't need any more so the cells are resistant to taking extra glucose from the blood and insulin is needed to push the glucose into the cells. When your muscles are working and using up their stores, the cells realise that they need to top up and suck glucose out of the blood stream without the need for insulin. I find that this will often continue during the night whilst I sleep if I have been for a decent walk, so I need to reduce my evening basal insulin dose to ensure I don't hypo overnight, particularly if I do consecutive long, brisk walks over a number of days, so doo consider basal reduction once this becomes a regular regime.

Well done on your excellent control so far, by the way!

Thanks Barbara,
managed a two mile walk but did dip quite low despite taking it really slowly. However I’ve looked at what I can do differently tomorrow with the advice from above taken very much on board. Great forum. Thank you everyone for taking the time as it’s really invaluable to ’newbies’ like me

 

[helli]

@rebrascora I think your logic is a little simplistic - it does not explain why weight/resistance training will increase blood sugars (although it does explain why it reduces them later).

The way I understand is that two things happen when we exercise
- our liver releases glucose to give us the energy that we need
- our body becomes more efficient at using that glucose with less insulin

The liver dump happens first so if we are stop/starting rather than continuous exercise, our body does not reach the efficiency needed to drop levels.
But, afterwards, the liver (and muscle) glucose that has been used is depleted and needs to be restocked. So for the next 24 to 48 hours, our livers drip less glucose and sucks up more of what we eat. Hence we need less insulin over the next 24 to 48 hours.

I appreciate my explanation is also very simplified.

 

[helli]

Thanks Barbara,
managed a two mile walk but did dip quite low despite taking it really slowly. However I’ve looked at what I can do differently tomorrow with the advice from above taken very much on board. Great forum. Thank you everyone for taking the time as it’s really invaluable to ’newbies’ like me

I know it is frustrating but it s worth it.
Also, once your body becomes used to that type of exercise, you may start seeing the impact on blood sugar is less so it is important to keep testing.

 

[Andywidd]

Cheers Helli,
I’m looking at it all with a positive mind set. I was thinking I need a new challenge - although this is not what I had in mind! Making notes and slowly working out what works for me and what doesn’t.

 

[Bruce Stephens]

Making notes and slowly working out what works for me and what doesn’t.

Libre helps so much! Though the 15 minute delay can be confusing (so after having a snack it's half an hour before you see any effect).

 

[everydayupsanddowns]

Well done on your experiments so far @Andywidd

Yes it will take time and some experimentation to get some strategies working for your various types of exercise. Weights in particular may be quite different as typically aerobic exercise lowers BG, but anaerobic exercise (sprints/heavy weights) can raise BG as glucose is released from muscle stores.

And then of course your diabetes may decide to move the goalposts at different times, and you‘ll find you need to tweak and adjust your approaches.

Keeps us on our toes eh!