Running and Blood sugar spikes

Hello all,

I’m new to posting about my type 2 diabetes.

I am a diabetic for around 8 years and been running/jogging for the last 3.

My old dr. told me it’s normal for my blood sugar to go from 100 to 180’s after running but everything I read most runners their blood sugar drops low.

Does anyone else have any information on this for me?


A lot of it depends on they type of running you are doing.

Describe your runs.

  • How long do they last?

  • What is your amount of exertion? Like easy, medium, very hard?

  • Are you using a basal insulin?

  • Are you using anything like metformin?

  • Are you using any carbs during your run?

  • If you are testing your BG before and during the run, what do those numbers look like?

If you are T2, your body probably responds to dropping BG. So what you are seeing is probably a result of the drop. It would be helpful to see if you are dropping first, and manage that drop to prevent the rebound.

I run around a 10 minute mile for usually 40-60 minutes I do it first thing in the morning before I even have coffee and no snacks or water while running. My BP is usually between 160-190 during the run if that tells how hard i’m running or not.

And then you spike more afterwords?

You can’t really tell exertion from BG. It could be from a lot of things.

How hard does it feel to you?

Perhaps part of that spike could be from waking up?

Do you take insulin?

I do not take insulin I take metformin slow release.

Blood sugar is around 95-110 before running and when I return home I test the blood sugar and it’s around 160-180 then back down to around 100 2 hours later.

I’ve been thinking that maybe I should wear one of the digital readers for a couple of weeks so I can tell how high it goes while running.

My Fitbit tells me what my heart rate was during the run which is usually between 160-190 depending on speed and distance.

Thanks for your input.

Just one other thing to verify. If you were to wake-up around 95-110 and NOT go running, but basically do the same thing with no food, no coffee, etc., what would your BG do?

I tested it just before running today BS was 87 right after running it was 157 and a hour after with only having coffee it was 124 2 hours after running with a banana for breakfast after the first hour it was down to 101. so it does go down in about 2 hours.

I go to the Dr. on Tuesday this will be the first question I ask him LOL

Thanks for following up I will try your text tomorrow morning as I tend to just catch up on ESPN on Saturday mornings. Then i go to the first Baseball game of the preseason LOL.

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When you get home from running, how long do you wait before doing the BG? Sometimes sweat or body heat can cause a slightly inaccurate number. Also, make sure any food has had time to take effect before you do the BGs (food obviously causes it to rise).

Back in the days I was running 10 minute miles My BG would spike because of the effort. Now I go longer distances at a slower pace and. My BG tends to drop. I carry Blocks to consume 8 carbs every mile or so.

T2 for 10 years running for 35 years, 73 now, slowing down a bit. My stride is shorter and my turn over is slower. But I still try, ))

FYI A1c 5.7 diet and exercise only DX with an A1c.c of 12.0


I always come home wash & Dry my hands before getting coffee pot ready.

I do not have any foods before testing.

Thanks for your response!

We tend to see this with anerobic exercise, but I frequently see this as a result of cross country skiing. I am a type 1. It is quite common for me to jump from 100 to 350 within 20 min of cross country or downhill skiing. I take insulin to counteract it.

Maybe you have a high percentage of muscle mass that means your performing more muscle work, making running more anerobic for you. Or, maybe you just run really hard. You might be the type to produce more hormone when you run. Maybe you get more endocrinological “boost” than some people while running. Your liver may be dumping sugar to help you, or you might be producing adrenaline.

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Well I talked to my Dr. about it and he thinks it’s because i do not eat before running and therefore my Body tries to produce food to fuel my run which is spiking my blood sugar. he says it’s actually a good thing as it will keep me in a fat burning mode for a longer amount of time!

Thank You for you insight!