Blood sugar dropping rapidly while running. Carbs not being absorbed.

Tagging @Juicyj and @In Response for you. They both run and use a pump so they may have some wisdom to share.

@Sideburnt when do you resume your basal?
My usual high intensity exercise is a 60 minute spin class. I suspend my basal half an hour before I start and resume 30 minutes before the class finishes.
As my insulin takes 30 minutes to reach its peak activity, I need to time the resuming so it is working when I finish the exercise not 30 minutes later,

And what insulin do you use in your pump?
I use Fiasp so I do not have to suspend so far in advance as something like NovoRapid.

Melgar said:

I’m going to put my penneth in. First thing I’m not on insulin, so my penneth may not be worth anything. Neither have I competed in 10 years. 10 k is a relatively fast run. By that I mean it’s mostly done in 30 - 40 mins depending on level. What type of carbs do you consume before your run? When I was running, before I was diabetic, I would consume complex carbs. I found them more stable over a longer period of time. I’m not sure how that would work being on insulin, or if it makes a difference.

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Makes sense to me (although I don't run).

Sideburnt said:

- Turn my pump off completely at midday (lunch) - to have zero circulating insulin by the time I run 5-7pm.
- Start my run at around 14mmol/l (250 mg/dl)

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What do you usually use to get to around 14 at start?
It may be worth experimenting with some slower acting carbs like a sandwich or such, maybe eaten an hour or so before your run?

I have exactly the opposite. Running always puts my BG up. I like to start at less than 5. 10k takes me about 48 minutes. Nothing to eat before or during run. Usually finish about 9 or 10.
Liver and muscles should really provide enough glycogen to keep you going.
Even half marathon I like to start at about 7, nothing to eat or drink, and finish less than 2 hours later with about 9 or 10. Although I cut my bolus a little.
Runsweet suggests not running sweet!

Sideburnt said:

I use a 50/50 mix of Novorapid and Fiasp. I suspend at least 3h before I exercise so I have little to no insulin onboard before I start.

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The ”no insulin on board” maybe why your BG rises after exercise. As you have highlighted you need 3 hours to clear most of your insulin out and it takes 30 minutes to become active so you have no insulin for the glucose you eat,
My understanding (although I have no medical training) is that exercise makes our insulin more effective not that it means we need no insulin.

When you run, all those stress hormones dump sugar in your bloodstream and you need some insulin to fuel you.
Runsweet website is very useful.

In Response said:

My understanding (although I have no medical training) is that exercise makes our insulin more effective not that it means we need no insulin.

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afaiu it's a bit of both, during exercise the muscles can also take in glucose directly without requiring insulin

Sideburnt said:

To be honest I usually have dinner an hour before. I usually have 40g or so of rice, pasta, potato. No bolus.

It's very odd. Id really expect fast acting glucose to do something within 15mins. Exercising or not.

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I'm surprised you're not higher an hour after eating with no bolus and no basal running either. Are you a honeymooner?

What is your 30g CHO drink you take just before you run?

I wonder if your supper is delaying anything other than pure glucose from being absorbed while it's being digested.

Heya @Sideburnt

Couple of things..

Firstly when you suspend your basal is your pump still correcting the high when you run ?

Next is time of day, I find time of day crucial, I can easily run for an hour in the morning without suspending my pump as I am more insulin resistant then, so mornings for me are the best time of day to run, evenings I am like you, I run for longer than 30 mins and despite suspending the pump I will still go low, I have to combine both suspending my basal at 3 hours+ before, so no active insulin on board, run with levels 10mmol/l+ and also eat a carby snack, so ideal time to pack a doughnut in ! Otherwise I am hitting a hypo within 40 mins, I also take jelly beans on long evening runs too as I can keep a few in my mouth whilst a run so releasing a bit of glucose, I run with a group in the evenings so am super paranoid about going low as I don't want to ruin the run for others and so I keep my phone handy to check my levels and if I see downward arrows at 6 mmol/l I stop and treat as a hypo at this point, running at 2-3 mmol/l would finish me so I aim to avoid at all costs. Also just keep well hydrated too as hydration can affect us t1d's too.

Try different time of day for the response, it's all about trial and error though, just do not give up !

Sideburnt said:

I'm struggling with scaling my running up to 10km I'm finding that my blood sugars are dropping rapidly which means that by around the 7km mark I'm unable to continue safely.
My routine is;
- Eat a moderate carb lunch at 12pm (20-30g carb) bolus normally.
- Turn my pump off completely at midday (lunch) - to have zero circulating insulin by the time I run 5-7pm.
- Start my run at around 14mmol/l (250 mg/dl)
- Take on 30g carb as a drink before I start
- Take on 30g carb half way through my run

I'm finding that as soon I start my run I drop rapidly, and that none of the carbs I take seem to absorb until I've finished my run. Then I go sky high.

I'm physically able to hit my 10km goal. But as soon as I drop down to 2-3mmol/l I'm done and it's both unsafe for me to continue, but also my energy disappears completely.
Do gels have an advantage over pure glucose? is liquid my best option? Any help would be greatly appreciated.

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Did you find any remedies for your exercise hypo issue? I just saw this and thought I’d chime in. I used to have hypo incidences with exercise on a regula basis. Earlier this year, i switched to a Medtronic 780 wifh G4 cgm. I stay in the Smart Guard mode, which provides insulin up to every 5 minutes as it anticipates my needs. The algorithm learns how your body responds and keeps your BG in range on its own delivery and not based on your preset basal. it anticipates lows and backs off too.

Smart Guard has a feature calked Temp Target that helps tremendously during exercise. I have had no issues with hypos during exercise since using it. It might be something to explore.

Also, do you still use mixed insulin? I haven’t, but I’ve read quite a bit about it from users who have had issues. I might look into that as well, if you still are having this problem.