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Basal reduction for exercise - what am I doing wrong?

ElyDave

Well-Known Member
Messages
2,087
Location
Ely, Cambs
Type of diabetes
Type 1
Treatment type
Insulin
If anything at all?

So, yesterday, porridge breakfast at 6:45, 30g carbs, bolused appropriately. BG went from 5.8 to 8.7 at 1 hour later and 6.1 at 2 hours later. All OK there.

Planned run after lunch (drop daughter off at ballet, run, pick her up, errands etc). Run planned for 1pm

Lunch was mushroom omlette, small piece of toast (15g carbs), eaten at 11:15, NO bolus taken.
BG before was 4.8, NO bolus, TBR set of 20% for the next three hours from 11:30
Plus one hour BG was 6.4, another 10g carbs eaten.

5km into the run, BG was 3.4, 10g carbs taken
10km (finish), BG 3.9
15 minutes later BG 5.1

Obviously here there was a small dump of glucose from the liver at the end.

Anyone got any thoughts on the rest of it.
I seem to be successful in avoiding precipitate drops like these about 50% of the time at the moment when dropping basal to 20-30% about 90 mins before the run.
 
Looking forward to the replies Dave, been looking at TBR's to account for exercise and unsure myself.
 
I think to plan for exercise using a pump, there's a lot of trial and error involved unfortunately and everything has to be accounted for in advance before doing it.

Also, its good to get decent control of bg levels but remember that a pump as it is, is not an artificial pancreas yet. The acting time for Novorapid is about 4.5-5.5hrs Its not 4hrs or 3hrs. So bg control has to be planned around the acting time.

Its up to you on how you control yr bg but I think you are trying too hard to control yr bg too tightly. Youve got more chance of losing yr hypo awareness than you have of getting nerve damage. What does yr hospital team recommend you keep yr bg levels stabilised at?

"So, yesterday, porridge breakfast at 6:45, 30g carbs, bolused appropriately. BG went from 5.8 to 8.7 at 1 hour later and 6.1 at 2 hours later. All OK there."
If I eat porridge (even nut porridge) I allow my bg level to be at 8.5mmol at the 3hr mark and not the 2hr. This keeps in line with how Novorapid controls my bg without causing me to go low within 3hrs and this is also with doing basal rate testing and keeping to a bg target of 6mmol. My last hba1c was 6.4% which also included some bg levels of 4mmol and 3.5mmol on a cgm. I do eat a lowish carb diet though so some of my meals are protein based with lots of low carb veg and a tiny bit of fat. Ive relaxed a tiny bit and altered the settings on the pump so that my bg target is a bit higher so my next hba1c will be 6.8% with any luck.
 
Have you tried a basal test while abstaining from carbs and exercise recently? Just wondering if your usual basal dose is still correct or perhaps should be reduced due to overall improving insulin sensitivity?

The fasted test would be a simple way to isolate and eliminate the possibility.
 

agree, that's why I had a low carb lunch and no bolus, last bolus before the run at 1pm was around 6:45 so over 6 hours, I reasoned that there should be no active bolus in any case, just basal at around 0.16U/hr in the daytime.


That's why I'm really trying to crack down on the bolus and get basal right for running. I'm able to stay steady between 4.5 and 6 on the bike with regular testing, basal reduction and taking in carbs as necessary, but it's more hit and miss on the running at the moment.

"So, yesterday, porridge breakfast at 6:45, 30g carbs, bolused appropriately. BG went from 5.8 to 8.7 at 1 hour later and 6.1 at 2 hours later. All OK there"
Click to expand...

We're not that far apart on our targets, I'm aiming for 8.0 2 hours later, the values I gave were readings, not aspirations. Porridge seems to give much less of a response than bread for example, as you might expect. I do adjust bolus slightly for different meals, but generally keep the same sort of ratio at 25:1. I might up my general target for a while (from 5.0 to 5.5) and see what happens.

Thanks for your thoughts.
 
Not since christmas, might be worth another look.
 
Try doing a basal rate test while you are exercising and then that will give you a good idea of how low yr bg levels go and also normal basal rates change on a pump so thats why pumpers test bg levels so much or get cgm.
 
remember I stated on a Cellnovo in October, tailored my basals on that ad then restarted on the insight in December, I retested basals then.

How often would you suggest retesting basals?

Also curious how you can test basals wile exercising, I thought that was the whole point of the basal test no food, no alcohol, no caffeine, no exercise?
 

Hi @ElyDave,
Just a quick thought - did you do anything particularly strenuous the day before that would heighten your glucose sensitivity?
Bx
 

Some people dont use TBRs to do exercise, they create another basal rate profile instead and use that but of course the basal need for insulin will always be a changing thing on a pump so thats why people 'tweak' the basal rate settings once they see the same thing happen 2 or 3 days in a row. Just because you set your basal rates up in December on the Insight, doesnt mean that they are still correct now. You might find that they have changed a bit esp when weight gain/loss comes about . Through eating a low carb diet and eating more nuts and cheese, I started to put on weight and as such needed to increase my basal. Now that I have lost some weight through leaving off the cheese and nuts but still eating low carb, my basal need has reduced Weather temp is another and theres probably even more reasons why basal levels change.

Before planning another basal rate test which should only be for about 5hrs at a time, see if the same thing happens when you dont do any exercise and if it does, then you will know the answer........do a bit of tweaklng and see how things go. You can always untweak.
 
Bebo321 said:
Hi @ElyDave,
Just a quick thought - did you do anything particularly strenuous the day before that would heighten your glucose sensitivity?
Bx
Click to expand...
Just a bit.

Day before was a nasty progressive gear interval session on the turbo trainer, top 7 gears in the big ring, 2' on/2'off moving up through each gear.

That one has the effect of upping BG, but no correction applied afterwards.
 
ElyDave said:
Just a bit.

Day before was a nasty progressive gear interval session on the turbo trainer, top 7 gears in the big ring, 2' on/2'off moving up through each gear.

That one has the effect of upping BG, but no correction applied afterwards.
Click to expand...


Hmmm,
Have you done that session before and then run the day after and noticed anything similar?
I know you are well read on the ins and outs of how the body works, so I would be interested to hear what you think to my theory:
During a bout of intensive training, you will mobilise GLUT4 receptors to the surface of your muscle cells in addition to creating a proliferation of GLUT4s. I have read that elevated readings of GLUT4s can be measured up to 53hrs after a bout of exercise. I wonder if this particular workout (all leg work) was enough to keep your insulin sensitivity higher over the following day's run?

(For anyone else reading this who isn't familiar with the mechanics - GLUT4 receptors or transporters are a mechanism by which glucose can be transported into a cell and no insulin is required)
 

Can't say I've noticed that effect specifically on this session, but I have seen increased insulin sensitivity days after most workouts, or rather a decreasing insulin sensitivity if I'm not active. Interesting on those elevated Glut4 levels though.

Recent History
Sunday - Nothing

Yesterday was a very easy session testing out a few recumbent bikes, about 30km of cycling in a bit over an hour (spread over 2 hours)so not high intensity.
Before that some time in the garden. Breakfast was porridge again, BG went from 4.3 to 8.7 with 0.5U bolus for 25g carbs, on 90 mins gardening it had dropped to 3.8.
Piece of toast (25g carbs, no bolus, TBR of 20% set for 4 hrs), 90 mins later up to 6.9 and off to test the bikes.
30 mins into it, BG 5.5, 20g carbs; 90min in 4.7, 15g carbs; 2hr 30 later 6.3 so no more carbs.
AHR was 131, MHR 156 (possibly when I fell off)

Today another run, 12km.
Breakfast was fruit and nuts, 20g carbs, 0.7U. BG dropped to 4.3, but came back up again to 4.8 pre lunch.
TBR was set at 30% from 10:30 for a 1:30 run.
Lunch was 30g of complex carbs, no bolus. BG before 4.8, 90 mins later 6.5.
Run went like this BG at 5km 3.7, 15g carbs; 10km 3.4, 15g carbs; 12km 4.9 no carbs
AHR 152 on this run, MHR around 160/

Only thing that stands out is the average HR on the run being higher, so potentially I was not high enough to trigger the liver dump, but high enough to reduce fat burning in favour of carbs. Two observations does not make a pattern, but I'm leaning towards basal rates being too high still. One more observation on a run tomorrow and then Thursday is an evening yoga day so I can basal test late morning to early evening.
 
ElyDave said:
Just a bit.

Day before was a nasty progressive gear interval session on the turbo trainer, top 7 gears in the big ring, 2' on/2'off moving up through each gear.

That one has the effect of upping BG, but no correction applied afterwards.
Click to expand...
If your levels went up then the glucose had to come from somewhere ie your glycogen stores .Did you 'top'up after that? Sheri Colberg calls the immediate post exercise period the 'window of opportunity' for replenishing stores with less insulin needed.
( I can talk, I kept on going low this afternoon just walking; albeit a very hilly walk)
 
That session was pre-dinner so yes, replenished, but taking care not to correct the high so as to prevent a later slump.
 
Definitely cause for another basal test tomorrow.

Today was my annual eye screening at the local community hospital, about 5km away so I rode there on the bike. Breakfast was low carb, 5g with no bolus and with a TBR of 30% from 7:30 am for a 10am appointment

Went like this woke at 5.1, breakfast, +2hrs 5.3. Had a fig roll (12g carbs) pre ride, at hospital 4.8, no carbs.

Pre lunch - 4.7, 35g carbs, reduced bolus to 1.0U (should have been 1.4 at my usual ratio). +2hrs 7.5 - really should have been higher with a reduced bolus.

Started a TBR of 30% at 3:45pm for the later run, tested about 5:45 at 4.7, 12 g carbs pre run.

5km into the run tested at 2.7, 10g quick acting carbs, 8km tested at 5.6. Dropped back to 4.3 pre dinner.

Early, low carb breakfast tomorrow and then basal test during the day.
 
No experience of pumps but from a running point of view you seem to be dropping off very quick in the first 5k. More carbs prior to the run would be an obvious solution but it seems as thought you are starting to exercise when your bloods are on the way down. From my experience it's always more difficult to predict and control compared to them being on the up.
 
Basal test definitely useful.

I think all segments need about another 10% knocking off them by the looks of it. Checked the luchtime segment today, will do early morning tomorrow.

Today went a bit like this
wake at 05:00 for an early breakfast at 05:45, BG 4.1, 25g carbs1.1U
08:00 - 4.4, 10g carbs to allow me to drop the car off for MOT
09:00 - 5.7 to drive into CAmbridge with my daughter (Shaun the Sheep movie, very funny)
11:00 - 4.7
13:00 - 3.4 - 10g carbs
13:20 - 3.9 - 15g carbs
14:00 - 8.2
17:00 - 5.4
18:00 - 4.8 - 15g carbs - pre yoga class
20:00 - 6.3 - post yoga
21:00 - 5.9 - pre dinner
 
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Yesterday much better
6:45 - 5.7
8:00 - 5.7
10:00 - 5.1
12:00 - 4.6
13:00 - 5.6 - Lunch
1500 - 6.8 - post lunch

might also be worth looking at the ratio again.
 
Good work there Dave. I'm sure the basal testing will pay dividends further down the line.

I'm also working on retesting basals after a recent insulin sensitivity improvement. I put that entirely down to losing a little weight recently.

Interesting question regarding how often basals should be retested, not sure what the answer is, personally I react if I suspect the basal dose needs to change.
 
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