Cardio Blood Sugar Highs

Hi Everyone,

At the end of June I decided to give up alcohol entirely, and went Keto. This is been great, except, when I have tried to do cardio my blood sugar skyrockets. A couple of weeks ago, out of sheer curiosity, I decided to try cardio when I had a morning low (65 or 70). After seven minutes of cardio, my Dexcom read 115 with the arrow facing straight up.
Has anyone else had to deal with this? I’ve looked online and I’m starting to feel like a real freak. And yes, I know the obvious answer is probably “take insulin”. It takes a lot of insulin to get me back down once that arrow is straight up, and usually ends in a roller coaster kind of day for me. I’m just wondering if anyone else deals with this.

Hi @Tosha. Exercise tends to make me drop but apparently certain types of exercise can cause some people to rise - it sounds like adrenaline may be a factor but I don’t know that there’s any guaranteed rhyme or reason. There is done discussion in the topic linked below but you’ll have to scroll through.
I don’t know how keto would factor in - that may be a question for your nutritionist. Like do many things with diabetes you may need to experiment (carefully) to see what helps keep your numbers where you want them.

Hi @Tosha omg why? Okay look the overly simplified reason is that your liver stores a kind of sugar (glycogen) and releases it when you need it. When you go super low carb, things begin to change that maybe your not used to seeing. Most people on strict low/no carbs see significant ketones. Many people with diabetes have conditioned themselves to freak out when they see ketones.

Your liver dumping sugar could be in reaction to exertion and can be associated with adrenaline. It could also be from prolonged carb deprivation in the presence of insulin. Many T1 athletes see that liver dump and bs rise with anaerobic exercise like weight training but it can happen anytime. If it is adrenaline it’ll likely minimize with repetition.

Especially with exercise, you can’t go off the CGM reading 100% because it will lag reality. You’ll end up over correcting with insulin and then having to treat with carbs.

There are some good athletic T1 books like the Handbook by Sheri Colbert and others. Try not to get all your info from google or you will lose your mind.

You are moving and testing and that puts you at the very top of the game for diabetes management. It can be harder but it’s well worth it so no matter what: do not stop-keep going!

Check in often and good luck :four_leaf_clover:

Sure Tosha @Tosha, I’ve noticed that happen for the past several decades - and I’ve never practiced a low-carb or restricted diet after the first couple of months of diagnosis.

Like @Joe said, at least your “early morning” event could be attributed to the normal intention [in all people, now just the lucky few, like us, with autoimmune diabetes] of the body’s circadian clock that tells the liver to dump glucose, and the glands to infuse adrenaline to get us started in the morning. Both those functions are intended to raise body glucose.

When you say “Cardio”, I’m hearing intensive workout, ANAEROBIC activity, where you are taxing your body to perform. Aerobic activity will tend to lower my BGL, whereas, anaerobic activity tends to drive up my body glucose. I don’t call myself an athlete, but many athletes do experience this happening; for me as I’ve aged, the breaking point of advancing from aerobic to anaerobic activity is harder to determine.

1 Like

That’s what happens to me too Dennis.

That is the same way. He may not want to bother with this but he might check his blood sugar in that 2 hr period. I wear a pump so I can just glance down and see but the inpin might be an option. This will work out but he might get more details from his body to confirm the details.

The liver dumping is real issue. It happens with fasting as well.

@Dennis If the event you’re referring to is the high after a low, which you might be implying is dawn syndrome, no. My BGs don’t typically spike during the morning, which is why I choose to work out in the morning. The cardio workout I am referring to was aerobic. And, as someone who has played multiple sports, both ANAEROBIC and AEROBIC, I know the difference between the two. I have noted that it is aerobic which spikes my blood sugar, and anaerobic which does not. I realize this is counter to what most people find is true for them, which is why I posted in the first place.

Frustrating, for sure. May I ask if you always work out in the morning? It seems like this has already been touched on with other replies, yet to share my experience, as well, morning exercise can be difficult for me. During certain times of my life, I was needing to bolus insulin before mild cardio, like jogging or circuit training with the elderly, without any carb intake. I’m sensitive that way, and can sometimes even need to bolus for carb-free caffeine due to its adrenaline effects, too. It’s not a great solution, yet I try to be like back in the dark ages of diabetes management and live life without a lot of flexibility to manage glucose swings. For instance if you know, it takes triple the amount of insulin to workout, match your basal insulin to that for your workout time (easier, obviously if you are on a pump). My insulin sensitivity varies greatly over the course of a few years, yet strict scheduling at least helps minimize some of the severities. Does you healthcare team have any input? There are even T2 oral agents that can be used to minimize the liver effect and/or force eliminate glucose out via urination. Good luck!

No Tosha @Tosha, it is not a high after a low, or as it sometimes is caused "rebound ". For me, In the morning, it is mostly the liver dumping glucose in response to signal from my circadian clock. Same as after a 12 hour fast in preparation for surgical anesthesia, i need additional insulin to maintain proper glucose level.

Hi, I am an avid runner (marathons and ultras with some 5k’s thrown in) with T1D. As others have said, it’s probably your liver dumping in glucose. As you begin to work hard, your liver is working to supply you with the fuel that you need, and especially if you start off low, it has a bigger reaction. I can generally keep mine in range while I’m running, but then when I stop I will shoot high for a while afterwards, unless I immediately bolus and pump up my rate if I can. I’ve found that the better I get in pre-run nutrition (such as a gel), the better I’ll do later. You will have to experiment with what you can have as part of your diet to make sure you have the fuel needed to go.

1 Like

Apologies, if someone already said this, but in skimming, I didn’t notice it. You need to remember what insulin does. It allows the cells to actually take in the glucose that’s in the blood. Without insulin, you can starve your cells even if there’s sufficient blood glucose that it wouldn’t otherwise be an issue. It follow that you can’t safely exercise without insulin in your bloodstream, regardless of whether the blood glucose level is low or high.

Now, perhaps I misunderstood what you did in this case, but it sounded as if you tried to exercise when your blood glucose was low in the morning AND WITHOUT TAKING INSULIN. I’m not an expert, but I think it’s possible that your body reacted by releasing a heavy dose of glucose from the liver, and that might explain the surge in blood glucose.

But the important thing I’m trying to point out is that exercise requires BOTH glucose AND insulin. So if you did what I think you said you did, you should probably rethink it anyway. :slight_smile:

I’ve often seen T1d athletes advise taking carbs and taking enough insulin to cover half the carbs, or something of the sort. For a morning workout, I’m likely to eat a 40g breakfast, bolus for 15 or 20g, and wait to start the workout until my BG is nearing 200. If it’s a long workout (an hour light run, say), I might add another 15g of fast carbs as I start the workout. Just my 2c.

I’m 76, BTW, diagnosed at 72.

1 Like

Before I was injured from irresponsibly running long distances every day, I had the pattern you are describing with my jogs. What do you think that metformin would do? Is it fast-acting enough? I met a T1 at a support group that I found slightly hyper-paranoid that mentioned being on metformin previously, as well as insulin resistant to only pineapple. I brushed her off as crazy. Now, that I understand metformin a bit more, it makes sense as it is not insulin/beta cell dependent, it merely suppresses the liver from dumping glucose. It has wicked GI effects for some, yet I hate the liver’s rebound effects and the somewhat dangerous maneveours I feel compelled to take to head them off at the pass with pre-bolusing for an anticipated high, etc. And, of course, now I have wicked food sensitivities. I am officially the crazy one. I miss running!