Need help with exercise and increased risk of hypo

Hello @mully10

Can you give us some background to how you treat your diabetes - are you on injections/pump, do you use a continuous glucose sensor, what insulins are you taking ?

I take insulin via a Tandem Slim pump, so an hour before I exercise I turn Control IQ off and I always ensure I have no quick acting insulin in my system before I start, I aim to start with levels at 9 mmol/l + to ensure I have a good buffer, I use a Dexcom G6 so can see the direction of my glucose, if it's an arrow going down then I take 15-20g of carbs, otherwise no need. I run so can burn through my BG levels quite quickly in the evening, but am generally good for an hour if I follow this plan.

@mully10

Hi, I have a different type of diabetes, but I inject and use a Libre. The approach I take with cardio is to reduce my meal-time insulin in advance of exercise (I can’t advise you by how much, but it will be trial and error to an extent) and to sip orange juice during exercise to keep my Blood glucose “topped up”.

Take care that your BG may drop faster that the Libre can show I.e. you can have a hypo before the sensor warns you. As a precaution, rather than rely entirely on symptoms, I also temporarily set my hypo alarm to trigger early (in my case around 5.0).

I also have an issue that my BG will have 2nd drop about 11 to 13 hours later (may not apply to you) - often overnight. So I reduce my evening basal injection too.

There’s more info in the following article, although it’s American so you’ll need to convert all the units to make sense of it:


It’s worth getting specific advice from your GP/Diabetes specialist.

Hi @mully10 I agree with Ledzeptt - don't rely on the Libre for readings as it's not a good measure for when BG levels are moving more rapidly, the delay means you can be going low before actually registering on your sensor, so using your scooby senses or a BG meter is best.

As you're on injections, just ensure that your last injection was over 4 hours beforehand, I find any residual quick acting in my system tends to drop me quickly so no active insulin on board can help prevent this.

In regards to carbs eaten for gym work avoid glucose as these can deplete quickly too, try and use whole grains/oats/pasta they stick around for longer, then top up with glucose in the gym, drinks are the easiest to keep levels topped up.

Yes it is a challenge but it's also very rewarding when you've had a workout and found a successful strategy to avoid the lows, I do the gym once or twice a week, I do enjoy it but for the same reasons as you I find it challenging, lifting weights seems alot easier than avoiding hypos...

Are you saying that if you reduce your morning basal (background) insulin your morning levels run high, or is the high the result of the long acting carbs an hour before you go to the gym?

You mentioned above that you go hypo after your cardio workout? How long after, is this still during your gym session? You could treat (i.e. eat something fast acting) after doing the cardio and before continuing, which might avoid running high beforehand and running low afterwards.

It would be interesting to know roughly what you're doing and for what duration. If you're not doing multiple hours, then it ought to be possible to tune your insulin and intake to avoid both highs and lows (within reason, this is diabetes, so it's different every time)

I'm interested to hear that dextrose tablets make no difference while exercising, they ought to be absorbed quite quickly, but we're all different. I dislike the taste/texture so stick to Skittles, though I used to use OJ too. One thing to note is that digestion is delayed during exercise, so you do need to use fast acting carbs once you start exercising.

mully10 said:

Thanks to both of you for your advice, I felt a little overwhelmed to be honest.
I did reach out to my diabetic specialist, but the info felt a little wooly.
You have endorsed what I was trying to do which was reducing background insulin in the morning and trying to eat slow burn carbs an hour prior to going, it feels quite wrong to be letting my bloods run higher to accomodate, but thats the way it is.
I think the fruit juice in the gym is a good call, dextrose tablets make no impact when I am in the gym, only after I have finished.
much appreciated.

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My dad had to do that he was type 1 to stop hypos at night