Adjusting basal for exercise

Status
Not open for further replies.
R

Radders

Well-Known Member
Relationship to Diabetes
Type 1
The instructions that came with my pump said that I should only adjust my basal for exercise of more than 45 minutes' duration. Since I never exercise for that length of time, the only exercise for which I adjust my basal is swimming, because I have to take the pump off.
Over the past few months I have started cycling to work (4 miles each way, started off taking 30 minutes but is now down to 22 minutes one way and 24 return as it's uphill) and have been having more hypos than I would like, despite adjusting my bolus doses.
Question is would others carry on reducing boluses, or would you reduce basal as well?
 
Start with basal testing
 
I often reduce basal with a TBR even if not exercising at all, so... Yes!

I suspect that the advice is probably based around the fact that it can take a while (probably at least 45 minutes) for a basal adjustment to begin to take effect, even if your basal adjustment is profound.

However I did notice when wearing a Libre sensor that I seems to be able to halt a slide into lower numbers with a short, sharp TBR. Perhaps 0% for 30 or 60 minutes - as long as I had 30 minutes head start. In fact that is just what the MiniMed 640G does with smartguard.

I would say that a combination of further basal reduction and TBR are worth experimenting with. Particularly if you are keen to avoid extra carbs.
 
Thanks Mike. What would you say is the advantage of using a basal reduction compared with reducing bolus?
I cycle to work after breakfast, so I don't have a choice about reducing my breakfast bolus, and what I've been doing in the afternoon is saving what was part of lunch until home time and not bolusing for it, so effectively reducing my lunch bolus. I'm fine during the exercise when I remember to do this but am getting hypos an hour or two later.
 
I see both as working hand in hand. Basal adjustments seem gentler to me. Better at stopping/correcting drift rather than sharp increases/decreases where rapid carbs/correction doses seem better. But basal *and* carbs/bolus reduction have worked well for me in combination.

Why can't you reduce your breakfast bolus? When I went to gym soon after breakfast I would reduce bolus by 20% and then reduced basal by 50% for a couple of hours. Keep at it - you'll find the combination that works for you 🙂
 
Today I cut my breakfast bolus to 1 unit and staved off the am hypos. Reduced lunchtime ratio by 25%:not enough. Bigger reduction needed tomorrow!
 
Hi Radders

Mike mentions about the basal change taking about 45 min to take effect. I use that idea to time the TBR. I walk after our evening meal, and use a 50% TBR (found by trial and improvement) which I set at the start of our meal. When I tried using a reduction in bolus instead I then got the after meal spike which I prefer to avoid. For bigger exercise, full day of walking or swim training session I will use a combination of Bolus and basal reduction.
 
Thank you for your input. When it"s not too manic at work, I walk for 20 minutes after lunch purely to reduce the post meal spike. I was surprised to find that since I am cycling to work I now need to reduce my bolus at lunch as well, four hours later!
Do either of you find that your basal and/or bolus needs continue to be lower after the exercise as well?
 
For swimming I use 50% TBR one hour before I swim (also no bolus during swim) and leave the TBR on for half an hour after the swim. In general I leave the TBR on for about half the time the activity took place, but then there is the fudge factor of how much CHo I ate during, how energetic the activity was , when I eat next as I sometimes take out a bit of bolus at following meal.. So that is my starting point and then I adapt and change as necessary. Then just when you think well that is sorted it changes!! So just find the best fit for you, keep monitoring and keep at it.
 
Thanks SB. Would you even bother reducing basal for a 22 minute bike ride?
 
For a short ride I might still use a TBR 30 min before I started and stop it once I set out. However that is because I just prefer to keep my bolus the same each morning as I now have a plan for porridge also hat takes care of the spikes, and the more gentle adjustment of the TBR seems to work for me.
There is no short cut thought. You will just need to try things, record, review and adjust until you find what works for you. Be patient.
 
Also need a TBR of 140% to watch the tennis!!!
 
I feel that TBR is something I've underused, probably because I scared my husband with one not long after getting the pump. I had tried a TBR after eating lasagne and the alarm at the end of it coincided with a bad hypo. I woke up to him panicking and shouting "why's the damn thing beeping" while trying to get me to drink Ribena!
 
I gave up going to the gym when my knees started complaining, but these days if I've exercised more than usual (day of DIY or 4-5 hour walk) I would need to take action for it (50% TBR and additional carbs dripped in) and then later in the evening, after evening meal I need to set a 80-85% TBR through late evening and most of the night. Without that I can easily dip below target range while I am asleep.

I think it very much depends though, as this didn't happen when I was exercising more regularly and running 5-10K 3 times a week. At that stage I just needed less basal on a permanent basis. these days my exercise/activity is more occasional.

As Pumper Sue says, it might be worth doing a basal test if you are seeing these hypos regularly. I would think that if you ride to work 5x a week then that could be accommodated in a fasting basal test structure. Many people find they do OK exercising with only basal on board and not eating breakfast (see http://insulinnation.com/living/5-tips-to-better-exercise-with-type-1-diabetes/). Though you'd need to be cautious and test test test obviously! Perhaps try a ride before breakfast on a weekend when you have more time to observe the effect and can choose a route on cycle paths/away from busy roads.

I just do wonder whether you are on too much basal in the morning generally.
 
Last edited:
Test, review, adjust, test, review adjust, ....
It is worth it.
 
Mike do you mean do a basal test and continue to cycle? I must admit I feel scared to do that. If I have no breakfast I am sure I will go low, and I don't want to risk doing that on the road. Hypo signs are easily disguised by General weariness when I exercise!
I have no means of getting to work without exercising as I live a mile from the bus stop and don't drive, so doing a normal basal test in the morning is tricky to say the least, but until I started cycling I was fine. I've done basal testing at the weekend and found it very variable. One day I get an increase at a certain time, the next I am stable at that time, and there being only two days I then have to wait a week to repeat the experiment!
 
You could try TBRs for the cycle ride, and that might give you an idea of how to adjust your basal rates for the mornings on weekdays. I have five profiles and choose which one for the particular day I have planned. So you could then set up a profile with basal rates to use for workdays and others for weekends. Talk to your pump trainer and see what they think.
 
Thanks SB. I only see the pump trainer when I get a new pump - I do understand about different profiles though. None of the professionals has suggested using a TBR before so I will try that.
Another question though: if I can adjust for the bike ride by using a TBR, why would I not just do that, rather than setting a new profile? I don't always set off at the same time every day, certainly not to come home, so wouldn't building that into my basal profile cause problems?
 
I was assuming you had a regular time for going and coming home from work. If it is a changeable time then as you say TBRs are the answer. Just keep working at it to find what works (but remember that it will then just do its own thing because it can sometimes!)
 
Thanks SB. Is it just a case of trial and error, or is there a way I can work out a starting point?
 
Status
Not open for further replies.
Back
Top