Bolus and Workouts

Hey everyone. I’m newly diagnosed and still figuring things out. One thing I’ve noticed is how much my insulin sensitivity increases following workouts. I typically lift 3-4 times a week, usually around 10am. I’ve had some pretty bad lows after lunch following my workout. I’m not using much insulin - usually only 1 unit with for lunch (20 carbs for me) - but I will check half an hour later to see a line heading down on my Libre that looks like I never had any carbs.

So, here’s my question: Would it be better to eat first and then bolus if I’ve recently worked out? Or, in your experiences, does skipping the pre-bolus increase the risk of going high too much?

Would love to hear some thoughts!

Hi Kyle @KLock good to see that you are “working out” and trying to keep your body in the best shape possible. Diabetes should not limit you in any way, but you will need to observe how different activities - eating included - affects you; exercise appears to affect each of us slightly differently.

For me, aerobic exercising tends to keep my glucose level steady keeping me from spiking after a meal and gradually pushes me down as exercise continues. During anaerobic exercising [resistance work-out], my glucose will tend to rise slightly and then suddenly drop 4 to 6 hours after.

You are new here and probably have not yet seen the exercise discussions. I suggest that you use the search feature at the top-right and put in your key-words. When reading those discussions, keep in mind that works real well for one person might not work at all for you ; folks who have been living with diabetes for a long time have noticed how some activity’s effects change from time-to-time. Good Luck!

hi @KLock, I think your situation may not be typical, in that you are very likely honeymooning (your body is still making insulin) and you are working out.

at what blood sugar are you starting your workout? ending? activity can change your insulin sensitivity (and by change I mean make you VERY sensitive to insulin) for up to 8 hours afterwards. If your body made NO insulin, you may find you have to take 1/2 your normal insulin. In your case, you may find you need to take less, or even zero insulin for that meal.

the way you tell is by making a change and then doing more blood testing and Libre scanning afterwards. Be aware that a CGM/Libre are less accurate when your blood sugar is changing over time than they are when your blood sugar has been not changing quickly. Verify your Libre by taking an actual finger prick BS test.

you should NOT make changes to your insulin unless you are comfortable making them. You should always discuss changes with a doctor or CDE, but eventually, you will need to make all your own decisions about when and how much insulin to take. Over time and experience, these decisions become routine. A great reference is the book “Think Like a Pancreas”.

a great piece of advice from one of my doctors: you can always take more insulin. meaning, if you find you are higher than you want after a meal, that’s when you can do a “correction bolus” to help bring your blood sugar back down.

this will likely ALL change, as your body stops making insulin. good luck. hope you are ok.

Hey @joe - thanks for the reply.

For an average day, let’s say I start my weightlifting at 120. After an hour, I’ll probably be somewhere between 130-140. I’ve observed that if I do nothing and just let my BG’s do their thing, I’ll start to drop pretty quickly about 45 minutes later. Unfortunately, I only made this observation after a misstep. I had pre-bolused a meal shortly after lifting, only to see half an hour later than I was nearly hypo.

My strategy lately has been to wait for the drop, catch it with a couple bites of a protein bar, and then bolus for my meal once things have leveled out. Even with this, it seems like my typical insulin to carb ratio isn’t sufficient on days when I lift. The insulin always wins, and an hour later I’m eating fruit to bounce it back up.

I’ve already discovered the my basal at diagnosis was too high, and worked with my endo to bring that down, which has helped quite a bit. But I’m still working out the kinks with mealtime bolus and activity. I appreciate your advice!

Hi Kyle, as mentioned above, you’re probably in the honeymoon stage. Your insulin needs will increase over time, maybe quite suddenly. Your basal insulin may be too high for now. Christel Oerum, a fitness expert, runs a blog and two Facebook groups, Diabetes Strong, and Diabetes Strong Community that you might find helpful. Here’s a link to a list of exercise-related articles on her blog. Keep working out and tracking your impacts - that is a big part of long term success. Also consider Adam Brown’s articles at DiaTribe. For example, here’s a book you can get at name your price.

@KLock yea, your basal shot is too much on workout days. this particular thing is much easier with a pump. your choices are less basal on workout days and deal with highs between meals and before you work out, or no shot at lunch and carbs.

since you’re lifting I am assuming you are trying to build muscle. oranges/lemons will help vit C seems to speed recovery as well as banana. You likely need protein as part of after/recovery anyway. this is not a great plan if you are trying to lose weight…but for building it can work.

just like @mikefarley said… this will all go sideways if you are making insulin, because it will eventually stop - as that stops your basal and bolus req will increase, and control will be trickier, but if I can do it you can too.

Hi @KLock I’ve noticed that when I lift for thirty minutes or so, my blood sugars start to go low. One thing which can possibly help is protein, something like peanut butter (if you don’t eat meat). Protein can help stabilize your blood sugars.
Aerobic exercise can affect you differently. For me, I used to play rollerderby. When I first started, the stress and adrenaline would raise my blood sugar. Then, as I got used to it, I noticed mid-practice lows. At that point, I would preemptively eat something that was a mix of carbs and protein to try to account for the planned exercise.
Since you’re newly diagnosed, you’ll definitely want to keep doing a good job of keeping an eye on your blood sugars. For me, my continuous glucose monitor has helped me with that. If that’s an option for you, you might want to talk to your endo about it. Hope that helps!

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Hi @KLock ,

I work out with a personal trainer two times a week at 7am and we do mostly weights. I’m somewhat newly diagnosed (3 years ago) and I still have some function in my pancreas - I’ve noticed that when I workout my body uses that insulin more efficiently and I don’t really need to bolus for food throughout the day (especially if I’m eating healthy). I’ve noticed the same thing after spin class, so for me anaerobic versus aerobic doesn’t make much difference (although it’s “supposed” to). Again, I think it’s just the little function in my pancreas kicks into gear after I workout. For lunch, I will bolus AFTER I eat, and usually only when the trend is double arrows up. Most days I don’t need to bolus at all for lunch unless I have restaurant food. I control my disease with almost only basal (A1C is 6.2 and my basal is a steady 120-130 at night). You might want to try going without a bolus one day after you workout and see how high you spike and go from there. Good luck!

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Hi Kyle, I’m a 76 year old who just became a T1D due to chemo in Sept 2018.

I work out 7 days a week MWF I usually swim 2 miles. (My pace is about that of a snail, it’s about 2 miles). I find that I drop about 50+ mg with each swim. On TThSa I do 1 hour of elliptical trainer and then 1 hour weights. I again will drop about 50+ mg during the elliptical, then will rebound about 40+ mg during the weights. Sun I do a 7 mile power walk. Takes about 2 hours and will again drop 50+ mg. Some of these events drop me down to below 75 mg/dl. I also find that going in a whirlpool or a hot shower will elevate my readings.

So the only thing I can say about your experience is you may have an elevated reading after your weights, depending on intensity. This level will drop off after you have finished(time may vary)

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Hi Kyle,

Finding balance with blood sugar and exercise can be super frustrating but whatever you do, do not stop working out!! It is different for everyone and sometime even different day to day for the same person. Typically, exertion can affect the blood sugar up to 12 hours after a workout. That’s a big window. If you are not already, it might be a good idea to eat fairly soon following a workout. If it’s a hard workout, you may not need to bolus. It doesn’t sound like you eat a lot of carbs. Are you on a pump? You may need to adjust your settings for the days you lift/workout which your endo can help you with. My suggestion for the moment is to carefully log your food, workout, and BG levels with times so you can see your patterns and make necessary adjustments. You are not alone in this. Good luck!