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!

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After an easy jog, whether 30min or an hour, my BG drops gradually and steadily. In hard trail runs my BG will sometimes raise and sometimes begin dropping quickly toward 15min. Regardless, of whether it rises or falls during my workout, I may hit hypo events for the next 12 hrs. I often lower bolus on days I run. Post run refueling is usually 40-50 carbs with a 1:20 ratio instead of my usual 1:14. I try not to mess with basal too much because its dropped me in low 40s as I slept. If I reduce, I have BG rises with no donut to show for it.


Mine are rather a gradual low, over a period of several hours, 5-6+ hours. If I don’t miss any runs on consecutive days, this will become my new normal, and I can then program a lower basal instead of relying on temp basals. However, I tend to miss a run here and there and that complicates the process since I then have to rely on temp basals.

Having said that, I am using Loop, and it is so much easier to rely on temp basals, since that is essentially what Loop is programmed to do! I still have lows, but far fewer.

I would recommend using some temp basal, even if it just a minuscule amount lower than your normal basal. Just go slow about it. If you still go low, the next day reduce a tiny bit more. Try to gage how long you need the reduce base for. Is it just 5-6 hours, or is it 12 hours? A CGM would help you you to see the trends.


I have Dexcom G6. Had it for almost a month. It has been awesome for helping see trends. I’m newly diagnosed LADA, and was benched from running- and all exercise from Oct last year til March when I finally saw Endo, who gave me correct Dx and insulin instead of the slew of meds that my family doctor had me on.

I’m not familiar with temp basal. I’ve been researching and journaling constantly so I understand this disease. I was told by endo not to mess with basal insulin (Tresiba) unless I have consecutive days of AM BG readings out of range.
Sometimes I prepare and raise my BG up to 200 before heading out, for fear of hypo on the trail. That cant be good. Advice?
Thanks to Dexcom for alarms.
As far as insulins and my sensitivity. It changes. In AM same amount of bolus may not work as easily as in the evening. Even on non run days I have a natural dip before bed. I’ve been keeping BG around 200 before sleep. But that cant be healthy.
I’m not on a pump, maybe that’s a solution?


Hi @ValidLADA!

I’m sure others will be through with thoughts on it all, but the first things that came to mind when I read your post were that you’re taking Tresiba (which remains stable throughout 24 hours or longer… if I’m not mistaken?) and that you’re having some dips that you’re accommodating for by running your blood sugar up. A pump most definitely will give you more flexibility, but maybe even a different long acting like Levemir? I also run and am wearing a pump currently, but I tried a spell on manual injections. I found being able to vary my Levemir doses and break them up throughout the day helped to minimize dips and climbs. I also learned running at the tail end of my Levemir dose meant needing fewer carbs during my run.

It sounds like you’re brand new to it all, so I don’t want to discourage you from learning the basics. They’re important. Just keep in mind they’re written for the masses, and there are a million ways to get it done. You’re in the right place to learn. :slightly_smiling_face:


No, starting out around 200 is not the way to go.

There are a lot of different ways to address this…

But so much of it depends on your personal situation. There is no single method that works for everyone. It takes time and experimentation to come up with a good plan.

If you want to work on this, I would encourage you to start a thread about your situation and we can work on it. Lot’s of information we’d need to work through.

You can look at some of the other threads on exercise - like @daisymae’s, @Nickyghaleb’s, @T1Allison’s, @Trying’s, etc., and see the process. It takes time to get it all ironed out, but it works.


@Eric thanks! I will start a thread in the morning with specifics. @Nickyghaleb hi! Thanks for the support. Please look for my post tomorrow :grin:


Hi @ValidLADA! Just checking on you. How’s it going??

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Hi! I’m well but got crazy busy preparing for hubby’s Bday weekend. I know my post will be long because I’m wordy. I will put it in Sports and Exersice forum. How are you!?!:hugs: