EXTREME exercise

I am just curious, what does everyone do as far as preparing themselves for a very, very tough cardio workout when it comes to your insulin preparations (cut backs) and bolusing before meals before you work out.

Today I went to go work out, and I ate a subway sub, and didn’t give myself any insulin for it and I checked my blood glucose after I worked out and I was 180. I ATE A LOT of carbs! I guess I am still trying to figure out what I should do for my ratios and all of that fun exciting new stuff! Help would be appreciated! Thank you!

I am trying to have maybe 10G before I work out and 5-10 more G of carbs every 3 or so miles. 10 miles is the most I’ve run recently but I have a few longer runs I want to do this year and will have to run a lot to get ready for them. I try not to run up much > 120 most of the time though? I have tried some smallish, like 10G servings of longer acting carbs before maybe a 40 mile bike ride (around 2 1/2 hours?) and it works ok to keep from running out of gas. I like to take more smaller amounts of carbs to avoid spikes.

The only other thing I could think of is some sort of insulin on board or maybe that your basal was elevated. You must be working out really intensely! I am pretty much doing all cardio, either running or elliptical and occasionally mix in some crunches. I had done a bit more intense workouts a couple of years ago (I blather about it on my page a bit more…) but during the harder ones, would just turn my basal down a lot but keep some going. I had a lot more trouble running low when I was in my early 20s and always wondered if there was some sort of metabolic ‘gear change’ at that age that threw me off? I didn’t really think too much about it at that age though?

Good luck w/ your endo!!

If I run a marathon (which takes me anywhere between 4 and 5 hours, so the “running” part might be debatable ;), I’ll usually have my normal breakfast than check my blood sugar a little bit before the race. If it’s under 100, I’ll usually eat something within the 20-30 carb range (fruit or a small PB&J sandwich). During the race, I’ve been using either the Gu Chomps or Cliff Shot Bloks (I hate the actual GU), and take one about every 30-45 minutes (they come either 6-8 a pack). If there isn’t a lot of support on the course, I may also try and take a small bag of almonds and raisins (for a 22 mile trail race, I actually used a CamelBak loaded with a couple of sandwiches and fruit as well). It’s definitely not an exact science, and other factors come into play (particularly temperature). I’ve also found it very important to hydrate, as my numbers seem to skyrocket if I’m not taking in enough fluids.
I think, like everything, it takes a lot of experimenting to find out what works best for you, but don’t let it prevent you from doing what you want!

I eat about 30 g of carbs before my workout and only dose for 20. Then during the workout I usually drink a serving of powerade/gatorade (15 g carbs) and that will get me through an intense 90 min workout with my bg in the low 60’s by the time I’m done. If I add cardio onto lifting then I’m in the same boat as you. I have to go and have a snack before I start running or I will be in the 40’s in no time. Check out a new group on here for high intensity exercisers.

As folks have said, it’s all about finding what works for you, starting with the general guidelines. IOB makes a big difference for me as does the type and combinations of types of workouts I do. 9 times out of 10, I finish my cardio low, somewhere in the 50s or 60s if I can start somewhere between 120 and 160. If I make a lot of big changes to my pre workout routine so that I can start lower and end higher, they might make a 10 point difference immediately pre and post workout, but they will screw with my BGs for the rest of the day. I look at the whole thing as a long term investment over days, weeks, and years, so I’ll accept the short term out of range numbers if they result in more stable numbers in the long run.

I could be wrong, but I think it’s a little different when your on the pump, because you have fresh new rapid acting insulin delivered every hour. If use Animas, you have 4 different programable setttings. Maybe it would be a good idea to program a new basal right about an hour before you start working out. The IOB will not account for basal.

One thing that has helped me a lot, was getting a CGM. I have set my CGM to alarm me once I go 80 mg/dl, so that I have time to correct (before the hypo symptoms).


Good point,

When I think of IOB, I think of bolus amounts working that are above and beyond whatever basal amount you have working, whether that’s fast acting from a pump, or long acting Lantus or Levemir. I think that with no insulin at all, basal or bolus, exercise wouldn’t do much to decrease our BGs at all.

I know that, for me, the basal delivered by the pump is much more consistent and predictable than the Lantus I was using previously. So now, I don’t have to think about what time of day it is in addition to how long it has been since I took a bolus. With bolus doses still working, I get a stronger BG response that with no bolus working.

Oh hello there,
Usually for longer spouts of cardio i make sure my sugar is above 220 and even then i sometimes get low. And then usually my ratios after i workout are double what they usually are.

During and after workouts most people experience higher insulin sensitivity. You can actually double your insulin sensitivity. But “intense” exercise can raise your blood sugar, like sprinting or weightlifting. Longer cardio style will tend to drop your blood sugar. If you start to get extreme, then you also need to worry about hydration and so forth which can also affect things. But everybody reacts differently and it can really make a difference what “kind” of workout your do, the length of the workout and what time of day. Sheri Colberg has a lot of advice on how to manage your insulin regime during exercise. Her book “The Diabetic Athlete’s Handbook” is available at many public libraries, and her website also has lots of articles.

For a long cardio workout, like a long run, I generally eat 30-45 carbs 30 minutes before. I reduce my bolus by one unit for every 30 minutes of planned exercise, so this could mean no bolus at all. I don’t take a correction bolus either, because exercise makes me highly sensitive to insulin. (That’s me. It may not be you.)

I check my BG 30 minutes into the workout and if it’s falling I take some carbs, either 1 glucose tab for every 10 points I want to raise it, or a GU. (I tried Clif Bars - I find them too bulky to carry when running and too filling. Okay on a bike, though.) I continue checking every 30 minutes and if by BG is going down, I take more carbs. If your cardio is at the gym

I only change my basal rate if I’m going to be exercising an hour or more. Then I reduce it by 50% starting an hour to two BEFORE I start and time it to finish when I end. Extending it beyond that time might work for you.

I don’t do anything as far as changing my carb ratios. That’s just too much for me to think about.

Good luck,


Another way of working with adjustment of dietary carbs and insulin is the “ExCarbs” approach developed by John Walsh and advocated in his book “Using Insulin” (it is probably in Pumping Insulin, but I don’t have that book). Basically, if you are a carb adapted T1 and you are doing primarily an aerobic activity, you can calculate the number of carbs consumed by your activity. These are your “ExCarbs.” You can then choose eat those carbs and not change any insulin dosing, or you can reduce your normal insulin dose by the amount needed to “cover” those carbs, or you can do a mix.

Even with all the tables and calculating, you will still likely have to do what Terry does, figure out how you respond as an individual and figure out a regime that works for you.

I just realized I didn’t finish a thought. (typical).

If your cardio is at the gym, a good source of carbs is a sports drink, because you can leave it on the floor or put it in a holder rather than having to lug it around with you.

I do curcuit training 4 times a week and my diabetic doctor said get 500ml of water to 500 ml of still energy drink (if your in the uk then lucozade) and drink that, not like fizzy sports drink but a slow realease onem the ones called powerade? x

I always tend to forget to use temp basal for some reason. However, If I know i’m gonna do a heavy workout every day for a whole week, and if I know i’ll do it at a specific time; I then program a new basal into my “weekday” program. This way if I forget I don’t have to worry about it.

However, I do think that depending on the exercise you are doing, I think it’s a good idea to program your basal ALSO with the intent of possibly taking your pump off. In other words program your desired “exercise basal rate” and give yourself about an hour or two extra time before the exercise. I say this because you’ll have still have a full dose of basal just before the actual workout, and you may not want that…

I am so thankful i’ve found tudiabetes, because there are so many knowledgeable people here like, Terry and BSC. I’ve learned so much…I can’t think of any other forum were people are so willing to share their experiences in the same way…


It’s very variable. Even just for me, I don’t do the same thing every time.

Immediately after a meal (30-40g of carbs), I will usually get through most of the workout in range (70-130) except for maybe a small blip at the beginning. For workouts <1h that seems to work well without adjusting basal more than 10-20%, but sometimes I am running low at the end. For >1h I almost always do a greater basal cut, like 50-75% of normal, but that may allow the carbs to cause a more pronounced spike at the beginning.

Without a meal, I don’t like to run less than 3-4 hours from last bolus. I’ll cut my basal 30 min before the workout to 0. I’ll then reduce my basal rate for the entire workout depending on what I’m planning. Usually somewhere in the 25-50% range for the first hour, then in the 50-75% range after that to prevent my bg from spiking from lack of insulin. If I’m in doubt at the beginning about whether I will go low, I’ll pop 2-3 glucose tabs right before I head out. Many times my longer runs require a bolus at the end if I’m too aggressive with the basal cuts.

I’ve started turning off my temp basal 2 or 3 miles from home when I run. That seems to be pretty useful buzzing off the spikes that I was seeing some of the time?

Wow. Reading through the ExCarbs stuff, it laid out in a few pages what iook me sixth months to work through for myself by trial and error. Even since I started pumping, it was a tedious, sometimes painful process figuring out that trying to adjust basal rates for high intensity cardio of 30 minutes was probably a waste of time.

Good stuff. No doubt someone would still have to work out the specifics, but it’s a great place to start.

I just loaded Pumping Insulin onto my Kindle when I started on the pump back in Sept, but it’s been slow reading. I should make a better effort to finish the book.

I use odwalla juices, they are 45g for just a small juice. I do all the work of estimating how many carbs to use before exersize, then I keep that odwalla around for sips DURING the cardio class or spinning if I SENSE im dropping, or if I check & its dropping fast.