Can a spike due to exercise be problematic?

Currently undergoing a possible LADA diagnosis. After any type of exercise my BG spikes to 170-200mg/dL. It then drops causing me to go hypo. Is reactive hypoglycemia a thing with exercise? And can that spike be problematic?

Blood glucose will tend to spike with intense exercise, like intervals and weight training. Longer, moderate exercise will tend to reduce blood glucose. This is based on study reading and personal experience. I was certified as a personal trainer, although expired, a tendency to focus on reading studies, and have worked out for over 30 years.

Your experience might be different.


Yes, I think this is pretty typical. At least I experience this if I do not take precautions. I prepare for each of my runs to try to get to 0 IOB. I will take carbs and/or insulin to try to get to the best starting point for my run. I usually take 21g carb immediately before my run and at the same time bolus .15U or more depending on BG. This prevents a low during the run, yet gives me a bit of insulin to prevent a spike from the carbs. I also reduce my basal during the run, so I may get 0U for a few hours. This may cause a spike after the run so I will usually bolus a small amount, .5 - 1U, prior to the end to compensate for some of the missing basal. Of course, YDMV. It is a learning experience and everyday may be different! I learned so much of how to maintain a flat (or nearly flat!) BG prepping, during and post exercise from @Eric2 so I hope he will chime in here.


It’s normally what happens w exercise. Your muscles activate glucocorticoid to enter your blood stream. Then your muscles consume the glucose. So it is normal to see a rise then a drop.
It is probably not a reactive issue but if you still make insulin your system is I. Flux.
I try to eat some carb gel when

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Riding an exercise bike I will slowly drop, To go swimming/snorkeling for an hour I start a little higher and then reduce basal. Because I will at some point start to drop.

But I have also been snorkeling for up to 3 hours lately. The weather hasn’t allowed me to be consistent right now. So I start a little higher as I will drop at the 1 to 1 1/2 hour mark, then my BG’s will start to climb… I don’t have a great way to combat this as I am out in the middle of the ocean and depending on conditions depends on how much I climb. So I just have to take insulin when I am done. When I am more consistent with the 3 hours the climb started to mellow some as I got used to it. And when I get really used to it I will probably have to completely change what I do.

And then we can all be so different…exercise is a trick the elves like to mess with!


Are you taking any insulin? What is your insulin regimen?

The spike after could be caused by different things, but most likely it is a response to stress hormones from the exercise. Your body wants to fuel the activity. It releases hormones and also stored glucose to fuel the activity.

Those are normal functions of the body when exercising, except for most people, they can supply enough insulin to respond, so they do not spike. For us, the body responds with the same stress hormones and glucose, but does not supply sufficient insulin, so we can spike.

In a different post you mentioned that you have episodes of hypoglycemia, but you did not mention exercise in that post. So I assume the hypo drop you have is just a part of what you are dealing with, and may or may not be related to the exercise.

Are you eating enough to fuel the activity? Do you eat before exercising?

If the drop after exercise is predictable - meaning it happens the same time and in the same way, every time - then an appropriately timed preventative snack would probably be helpful for that.

Hi @Trying!


I am not on insulin. The spike seems to happen no matter the type of exercise. Granted, the hypos don’t always happen. Sometimes my BG will spike after exercise and stay spiked for a little while and then eventually come back down slowly.

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Thanks, @Eric2, I always learn something from your responses!!

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So would a walk spike you too?

Can I ask how much of a spike?

And do you exercise soon after a meal? Or do you exercise before eating and right when you wake up? Or is it more random times?


Yes I’ve spiked from a walk before. For example the other day I went for a casual bike ride my BG before starting was 112 then about 30 mins in my BG was already 178. And I had eaten about 3-4 hours ago.

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I agree @EricI You are a wealth of information with regards to exercise!!!
(Besides many other things too! :grinning:)


Since you are not yet taking insulin and it had been several hours since your meal, this spike certainly seems like it is hormone driven.

It becomes much easier to manage once you get the overall picture figured out. But you have hypo’s and also spikes. You mentioned hypo’s on another thread.

So it sounds like your body is reacting to exercise with hormones that drive your BG up, and then your body responds to that spike with endogenous insulin and it drives your BG down.

Yes, exercise can be figured out. But first it would be best to try to figure out the overall picture of what is happening with your body, and get some direction on medication from your doctor.

There are things besides insulin that can help spikes, depending on the diagnosis.

Where are you with your doctor? Are you still working on the food logs?

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:heart: :blush:

I just got the antibody testing today so hopefully I’ll have results soon. My doctor said there’s definitely something wrong and she’s hoping these antibody test give us an answer of if I have type 1.


Please let us know!

Once you get the diagnosis sorted out, hopefully we can figure out some exercise stuff.


I appreciate all your help! You have my deepest thanks!!




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I am using Dexcom G6 and am learning the OmniPod pump bolus technology. Wondering if anyone of you can help me understand why, as I am getting older (66) and doing similar exercises like swimming and biking which I have always done, my BG is spiking now when 4 years ago it would usually go low. I do recognize that as the intensity increases, my BGs increase. Personally, it appears that my (old) body seems to be more stressed by exercise these days and “activates more glucocorticoid to enter my blood stream.” Any thoughts appreciated on how I should treat this because the high BGs last for 2 hours and are certainly harmful. Taking a little extra insulin is “scary” ahead of swimming or biking for an hour.