How long after exercise do you see refueling lows?



We are looking into a different kind of strategy and timing for running. But its success will depend upon the timing of refueling lows. When (how many hours later) do you get refueling lows after exercise if you don’t refuel right afterwards?

For us, our preliminary info is that we appear to get a significant low about 15 hours later.


I’d love to know if someone has data on this. I did some research and found that some people see a low around 8 hours and 11-14 hours. But I am really hoping to see lows in the next 6-8 hours after running. @Eric, @Nickyghaleb or @Trying, do you know?

I am thinking of going running before school in the morning, but not refueling much afterwards, because I need a lot of insulin in the mornings at school. So this way, if my BG goes low after running, between 1 and 6 hours afterwards, it will lower my insulin need in the morning at school. That would be ideal for me.


@Kaelan Great question! I think @Eric is best to answer this :slight_smile: By “refueling lows”, do you mean lows due to exercise?

I will typically have reduced insulin requirements for the remaining day and overnight from a mid-day, long run. Usually I see this reduction within a few hours, and may need to reduce my basal if it isn’t already reduced (from a non-run day). So it is very possible a morning run will have the effect of lowering your insulin needs in the morning and thereafter. I know @Eric will probably still advise you to refuel after your run though :slight_smile: I think the running should still have an effect of making you more insulin sensitive, and have an effect of lowering your insulin needs.


Yes, I do think @Eric is the one to see to be sure, but I can say I seem to see the beginning of a dip a couple of hours after a big run, and the decrease in insulin needs can take me deep into the night. I don’t run in the morning as often as I would like, so this would be in response to a midday or early afternoon run.

Eric has me evaluating my runs according to RPE, or rate of perceived effort. I love this because instead of just thinking about a workout in terms of good or decent, or some other vague identifier, I now can assign a value. In general, the workouts that cross into the 6s and higher, which would be a solid moderate at the least, are the ones I start to see a more profound effect. I’m not sure what types of runs you’re taking, but are all on the same level in terms of exertion?

You asked about refueling. :woman_facepalming: No wonder I answered something else. I’m a terrible refueler. :grin: I am trying to nail down a post-run banana. That’s my big dream. So far I have not been able to eat the banana when I want it but rather when my blood sugar dictates it’s okay. That means I don’t get it sometimes for a couple of hours after finishing, which I know is not ideal. I have not noticed any difference in blood sugar following the variance in banana consumption. If I run hard, I have to be prepared to crash for many hours following. If I run at a leisurely clip, it’s insulin business as usual. No matter when the nana happens. So… I don’t know. :grin:



i have to refuel within a 1/2 hour (as soon as i return home from the pool) post swim. i take about 50% bolus coverage for my carb intake. sometimes, although not always, i need to do a lowered TB to get me through the night, but that doesnt start until after dinner time, closer to bed time. i do about a 6 hour TB which will end a couple of hours before i will wake up for bfast the following morning.


Yes, sorry I did not answer earlier.

That would be perfect for me :smile:

I started running at 6:30am the past couple of days. I did not refuel much (only 40 carbs, which is much more than I normally have for breakfast but much less than I normally refuel with). It did lower my basal needs early on, but I still ran high after 11:00am. Still, I think this might work once I can tune it better! Thanks very much for your help!


@Kaelan Fantastic!:running_man: I’m glad it is working for you. Yes, fine tuning is inevitable!