Keeping Blood Sugar Up During Cardio

Hi everyone, I’m new here and thought I’d reach out to typeonenation for some advice on maintaining solid blood sugars while doing cardio. If I’m on the elliptical or treadmill for 30 minutes or more, my blood sugar plummets. I know I can eat a snack with about 20g of carbs prior to exercising, but sometimes I feel like that defeats the purpose of exercising if I’m just eating to burn calories. Does anyone have any advice on this matter? Thanks!

Hi Sophie, I have the same problem and it’s frustrating. I’ve talked with numerous people (dietitians, CDE, doctor, etc.) and everyone says to eat protein with the carbs and to lower my basal rate about an hour before exercising. Nothing seems to work - either I go too low or too high. I hope you get some responses because I would love to hear what works for others.

Hi Sophiespieg,

I wish I had better advice but i don’t. That is one of the biggest struggles I have. When I want to “go hard,” my blood sugar always bottoms out. The only thing that works for me (unfortunately for your question) is eating a banana, some sort of slow-burning carb before the gym. It keeps me level while I work out. I’m sure you already read up a lot on health and fitness, but I know weight lifting also burns way after you leave the gym. Maybe lifting heavy combined with cardio can get you closer to your goals? If you’ve already tried this, just disregard my advice :slightly_smiling_face:. This is a long shot and something to speak with your doctor about (seeing as I’m a fellow T1D, not a doctor) but maybe on the day you go to the gym, you could reduce your long-acting insulin so that it’s not so reactive when you don’t need it to be. That’s purely theoretical, however.

In closing, diabetes sucks, but we are clearly strong enough to handle it, otherwise we wouldn’t be asking questions and seeking answers for working out. If you find a remedy, please do share with us!

Happy sweating!

I struggle with this as well. I typically try to disable my basal while exercising as others have mentioned. I think most frustrating for me is having to eat glucose tablets while I’m on the elliptical. As you mentioned, I feel like I’m defeating the purpose.

One interesting tidbit that I have discovered though is that if I push into an anaerobic state, sometimes my blood sugar actually peaks. I actually wanted to lower my blood sugar a week or so ago, so I hopped on the elliptical for about 45 minutes and really pushed myself and it just kept rising. I’ve noticed similar results from weight training.

Maybe there is some magic equilibrium where you can combine the two forms and maintain a stable blood sugar reading.

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I used to face this issue as well. I am not a professional, but the way I dealt with it was diluting a bit of juice with water to sip on during the workout. This used to help me maintain my sugar levels throughout the workout!

Hey all,

I deal with this all the time as an athlete of many sports. The more your practice, the better you are at dealing with the lows AND high of exercising.
Here are a few rules of thumb that I have put together with my endo (also an athlete):
°Have a cushion prior to starting, no matter what intensity level (7-10mmol/L)
°Drop the basal by 50%
°Aerobic: 30g+ carbs every 30 minutes. —You will not defeat the purpose. Since you will be mid workout at this point, the sugar wont even have time to store itself as fat or whatever, straight energy for the workout (athletes also have to be weight conscious).
°Anaerobic: you will go HIGH. Take a bolus right before your start. I take 3.5u for 20-30min anaerobic efforts (pump). Greatly likelihood of night time lows are likely after anaerobic efforts. Drop the night time basal by aprox. 20%.

Start by testing a lot when you workout to learn to associate various efforts to BG counter-reactions. A huge help for learning anaerobic vs aerobic efforts is having a good heart rate monitor and knowing your hear rate zones.

Mid workout snack suggestions that don’t suck: Fig bars, Lara bars, dates, maple syrup packets

As everyone has stated, this is something that you CAN work through but it may take some experimentation. I was diagnosed with Type 1 at the age of 40 and had spent my adult life being very active. Here are a few of the things that I have identified that have helped me get back on feet (I completed a half marathon 6 months post-diagnosis).

  1. You must plan your workouts in advance. I have a rule that I do not eat a meal or use Bolus two hours prior to a long cardio workout.
  2. I will have a low-GI snack prior to starting a run and I’m OK if my BG goes 30-50 mg/dL higher than my targets prior to starting a long cardio workout.
  3. I always consume a glucose gel ~30 minutes into my workout. If I am running less than 10 miles, I typically do not require a second gel during the run (I always have an extra with me, however!).

Best of luck and know that you will figure this out, it just may take some time. As always, communicate with your doctor and make sure you stay safe.

Hi everyone,

Thank you so much for your responses! I’m definitely going to consider and test all of this advice. I really appreciate you all!

hey! last year in my dance and fitness course we learned about specifically how energy is burned. it was really informative. as you’re describing the difference is totally about whether it aerobic or anaerobic exercise. this was a year ago so I am not 100% fresh on the info anymore, but we mostly got it from a book called “Smart Exercise” by covert Bailey-you and everyone should totally read it!! it’s important to stay in your aerobic heart rate zone if your goal is cardio because that’s the zone in which you’ll use oxygen most efficiently and hopefully will crash less!

You’ve got that right Gabriela, all exercise is not created equal. And the same exercise does not affect each of us, insulin & glucose wise the same.

For me [I am not a medical doctor but I do have 60+ years with diabetes trying to get this correct] when engaging in aerobic exercise I take less insulin - I set my pump bach as much as 80& about 90 minutes before I exercise and always have my Gatorade with sugar and granola bars with me. For anaerobic exercise I do not reduce my pump settings and sometimes need additional insulin.
What I need to monitor closely is my BG 6 to 12 hours after “good” exercise because at that time my BG sometimes plumits.


Hi! I agree and do similar things! It’s been challenging to find the right amount of basal reduction when doing various types of movement or exercise. it’s also challenging for me to find when that post exercise drop is because I move at multiple times everyday usually. as a dance student when weather permits I bike to and from, then have some type of movement class, sitting-academic class, stress at some point (rising bg), another movement class or rehearsal and/or teaching dance or babysitting. So the challenge is estimating what classes and times will be more aerobic and anaerobic and what will accordingly make it rise and fall, in conjunction with stress and types of food! it’s trial and error like everything else. I actually had a really good day of levels today. I almost always go high during ballet class but I woke up in normal range and made myself eat and bolus for breakfast before and then stayed in okay range through class!!! and then with more vegetables than usual stayed okay still. hooray

@gabimontoya what you just wrote here should be used as the Introductory Statement for a paper on why we [PWD] must learn to be our own primary care physicians.
Diabetes is with us 24/L, all day and every day of our lives, and not just those few minutes we spend every so often with “professional” diabetes care managers - CDE, Endocrinologist, etc. Adjusting insulin dosing by whatever means we choose to take our required medication to fit our constantly varying life style of activity, eating and emotional stress levels is something each of us must fully understand.

Just as in dancing where there isn’t any one tell-it-all book, there isn’t any “one way” for diabetes management; your activity level is certainly different from my present day activity. Your daily activity as student and dancer appears to differ from our granddaughter’s activity who is a professional dancer - Pointe Ballerina and part-time barista. To me, it sounds as if you have a really good idea of how best to manage your diabetes.

Hi Dennis,
SO TRUE. and interesting about your granddaughter. I used to do more ballet and pointe. sometimes I miss it. perhaps we collectively should write that paper you mentioned hahah (when I am not writing papers for 20 credits of classes that is). Thank you-what you said is helpful especially because it often feel like I have no idea what I’m doing or rather what my body’s doing, but I really do…