Foods to eat pre-exercise

my endo insists that i don’t go into the pool to do my laps until my BGs are up to 180 (not higher than 250) and i have tried to find combinations of foods to bring me up. i swim and cannot wear my pump during 1 1/2 hour of laps, but if my BGs are about 200 pre-swim, they come down to about 80 post swim. then i cover the hour(s) of missed bolus (.7 units) and am back on track.

but, i only have two known prep-foods and i want to expand my choices. i can either have a 1/4 of a snickers bar or 4 slices of banana w/ peanut butter. then i wait 1 hour for my BGs to come up, and then put on my suit and jump in. ( i won’t go in the pool with any IOB; do any of you exercise with IOB??? )

need all the help i can get, thanks everybody,
daisy mae.


Hi DM!
I’ve had more success with slower release carbs than faster release like a snickers bar. My usual food before long runs is oatmeal and a product called Ucan.

Longer release carbs stay with you throughout the workout, which is better than a quick spike and potential drop.

Check out Ucan and read about it. It’s like a slow 3 hour trickle of carbs. I really find it useful!!

I also try to do exercise with no IOB, but it isn’t always possible with varying schedules…

1 Like

Eddie, have you tried UCAN on its own? I’ve experimented with other resistant starches, and they don’t actually raise my blood sugar at all. They do help to buffer BG rise from carbs, though.

1 Like

@Daisy_Mae, my T1D swims a lot every week (he is on a swim team).

As a note on tracking your BG while you swim: if you have a Dexcom and a waterproof watch, you can figure out exactly which minute the Dexcom ping is due, then, every 20-30 minutes, come out to your phone or receiver just for the ping, then go back in. This way, you get a quick reading, eat something if needed then go straight back. My son does that every 20 minutes.


Small Apple fits the bill quite nicely for me

I have tried it on it’s own. If I take it with no insulin, and by itself, it gives me a very slow and minimal uptick of BG. I like it because it is a way of getting carbs with minimal impact.

I also like the feel of it when exercising. It seems to provide useful and burnable carbs.

I haven’t done enough experimentation to say conclusively how it impacts “other” carbs though. But given time, that will certainly be in the plans at some point…

Hate to break this to you… but you aren’t getting carbs, at least not in the normal way :slight_smile: The reason why resistant starches don’t affect BG is because they aren’t starch, they just look a bit like starch under a microscope. They are basically a form of soluble fiber, and they don’t get absorbed in the upper GI. You can convert them to starch with heat, although why anyone would do that I don’t know…

They get fermented in the lower GI and yield a small amount of fatty acids absorbed in the LI (the leftovers that don’t get munched on by gut flora). You probably know all this, but personally I don’t count my 30g of pre-ride RS towards my carbs. I also get a barely detectable (less than 5 mg/dL) BG rise, although that could be any number of things. Nicest thing about it is that it tends to do away with the initial BG rise from intense activity.

My understanding is that it simply resists digestion in the small intestine. That’s why it is classified as a dietary fiber. But the resistance is what slows it down.

The label says “slow releasing carbs” and lists it as about 30g. But I guess how much of that 30g you get is up for debate.

With the regulation on nutrition labeling, I would assume there has to be some useable carbs there.

I’m not sure about UCAR to be specific (I tend to use unmodified potato starch), but I believe the labeling as carbs is because the FDA hasn’t changed it’s labeling requirements to match the newer research. Resistant Starch is defined in terms of physiological function rather than chemical structure, so there are different types. They are, by definition, those starch-like polysaccharides that are not digested in the upper GI.

They look like starches, are labeled as general carbohydrate by the FDA because there isn’t another category (they really should be labeled as soluble fiber for consistency) or exemption, but have very different properties. I’ve done quite a bit of testing with them to help alleviate workout high blood sugars to great effect. I suspect that any rise in BG from the RS alone is probably due to some level of impurity (i.e., normal starch as a fraction of the consumed product).

Do you think there is nothing useable in there? Maybe, I don’t know. But if so, that seems to be a huge loophole in the labeling requirements.

I’ve also used a different form of sugar that is labeled as complex (it does not say it has simple sugars). It’s was a very weak chain of complex carbs. It “acts” like a simple sugar because the chains are weak and break down quickly. But because the chains are long, it’s not labeled as a sugar. But even though it would spike me, I felt no energy from it.

Maybe that’s the same thing. A problem with labeling!

Interesting stuff, good to know. Thanks!

Labels also count all dietary fiber as carbohydrates—that also seems like a big loophole… at least from the perspective of someone using insulin

1 Like

what would be your thoughts on having a full fat FAGE (greek) yogurt ? what has worked for me with the snickers bar is that it includes fast sugar, protein (the nuts) , and chocolate (which, for me, is a slow acting carb) but how many times can i eat snickers bars? i want to find some more choices.

i like the idea of the apple, though, as i suppose you can get your fast sugars plus the fiber. how long is your workout? i swim for about 1 1/2 to 2 hours now. when i started, i was swimming for only 1/2 an hour. also, since i swim, i have to detach from my pump, so the longer i swim for, the longer i am not getting any basal insulin. someone on TuD made a great suggestion which has worked well for me: to avoid the post workout spike, i give myself a bolus of the units i have missed during my swim. it has worked like a charm.

1 Like

There are huge problems in FDA labeling (or any labeling). The root of the problem is that food is a lot more complex than “fat,” “protein,” “carbohydrate” and fibers. You’re probably referring to a dextrin (although all polysaccharides are, in essence, weak or strongly bound chains of sugar molecules). And yes, they can raise your BG without providing much usable energy.

Resistant starches are, for practical purposes, soluble fiber. They aren’t absorbed in the stomach or upper parts of the small intestine, so they aren’t really given the opportunity to be converted to sugars (they are resistant to having the sugar molecules broken apart). They pass through to the large intestine, where they are quickly fermented by bacteria. The fermentation byproducts are gases (why they bloat some people) and short chain fatty acids. Most of the fatty acids are consumed by gut flora, and the remainder is absorbed by the large intestine. Because they are fatty acids, you do get an energy boost (if you consume enough to have an appreciable effect) which is pronounced when doing high intensity endurance sports (because you are likely to experience glycogen depletion and conversion to fatty acid metabolism at some point in a run, ride, or swim).

So, basically, the body treats resistant starches as a fiber and then a source of fat. 100% pure RS (which doesn’t exist) should have zero effect on BG assuming no other interactions, unless you’re in a truly depleted state and then 10% of the fatty acids that the LI uptake would be converted to glucose down the road. But that would be unnoticeable from a personal testing perspective I’d think. The great thing about RS for athletes is that we can derive a certain amount of energy from them: they’re great to combat bonking from glycogen depletion. The great thing about RS for diabetics is that they have this mysterious, and as yet unexplained (but scientifically verified), effect of reducing spikes. It might be because they act like soluble fiber and slow down absorption of other nutrients. But even when I exercise fasted (so no carbs to slow down the digestion of), using RS flattens exercise and DP induced spikes. I don’t know why, but I certainly make use of the effect!

1 Like

when your son jumps into the pool, does he have IOB? an elevated BG? is he on the pump as well as the CGM? i swim at my local YMCA; there is no one there to help me out except a lifeguard, who could care less. i keep a beach bag near by which i keep my meter, glucose tabs and a notebook in. i dont get out of the pool to check my BGs b/c i dont want to lose my swim lane. also, i stopped using my Dexcom last year as i was getting too frustrated with it, so i just test more frequently. also, i swim at different times of day on different days of the week. i have noticed that there is a little inconsistancy with my body’s reaction to my routine between lunchtime and late afternoon.

my biggest question is, when your son gets out of the pool to test and realizes he needs to snack and then jumps right back into the pool, doesnt it take his body a while to respond to the snack? he literally jumps right back in without waiting?

very curious,
daisy mae

Full fat real (hi protien count) plain greek yogurt with granola cereal is what I use. If I spike from arobic exercise afterwards, I take 50% of my correction ratio. So far so good. Real full fat Greek yogurt seems to slow things down. IOB I try to avoid, but schedule doesn’t always allow and IOB usually results in treating a pre-low indicated by my CGM and apple watch. Without yogurt or cheese, I go low whether my number is 180 or 100.

This makes a lot of sense because a lot of what I do is glycogen depleted, and also I am using a lot of fat during the work because I am unable to get there on muscle glycogen alone. Normal people (not elite athletes) generally have only 10-13 miles of muscle glycogen in their legs for running, so what you are saying makes perfect sense in terms of getting a boost from the fatty acids during long runs.

It’s kind of late in the training cycle now for me to use it in my next race, because I like to get completely comfortable before using things in a race. But you have given me a lot of great info, and I appreciate it! We should open this up in a new thread sometime and talk about it.

I didn’t mean to derail your discussion Daisy Mae!

  • We try to have as little IOB as possible when he jumps in, at least 3 hours away from a meal - but this is not always possible.
  • He elevates his BG to about 150 before going in, by eating pure carbs 30 minutes before. We have not noticed any significant difference when using complex carbs, and we are worried that he may not be able to elevate his glucose quickly enough if he has protein/fat right before swimming.
  • He does not have a pump. He is on Lantus - but very low basal because he exercises so much. When he stops exercising for a week his basal needs go up by about 60%.

Yes, except if he is low. His practices are intensive. We know, from experience, that he uses approximately 15 carbs every 20 minutes. So, every 20 minutes, he tests, typically eats 15 carbs, and jumps straight back in as long as he is above 80. If he is below 80, he waits a few minutes until hs CGM shows him higher.

A few notes:

  • occasionally he won’t use his CGM - for instance if there is no signal. He keeps a small towel to dry up just his hands, dries them up, waits a minute, then tests with a strip. If his CGM shows him low, he also tests with a strip.
  • we have found out that it does not help to keep your glucose elevated by underdosing the meal before. When he does that, his BG drops very fast in the next few minutes after he starts.
  • as long as he tests on schedule, he hardly ever goes low. His carb consumption while swimming is VERY steady.
  • he replenishes right after practice by taking advantage of the fact that his BG keeps going lower after exercise. Typically, he downs 8-12 oz of whole milk right after practice, as we are driving back home. He may need to dose some but not much - depending upon where his BG is when he stops.

i´m finding this post very interesting. I am a diabetes educator and have lived w type 1 for 31 years now. Ive always done physical activity but it was just till december this year that I decided to run, i know, i know, better late than never. I know the protocols and guidelines but, as we all know, diabetes does not always follow the book :slight_smile: great advice, thank you all. P.s. Yes, I exercise with IOB, I try not to but exercise makes my liver produce glucose, specially when running (not other activities though) so i´ve even had to bolus mild corrections. My medical team is aware, I usually make my own corrections but I let them know just in case.

1 Like

Two very different techniques I have learned to fuel during runs.

One is to keep my basal going, and “feed the basal”. I take in carbs along the way, small amounts frequently, like grazing.

The other technique is to “fuel the run”, and" bolus the fuel". That is where I take a small bolus at certain times and and consume carbs during the run.

Those are the two different techniques I have learned for long runs. For short runs, I just try to have level blood sugar at the start, and only have carbs or insulin as needed.


I tried that yesterday, got to run almost 5km (not much but made me feel motivated as a newbie runner LOL). So grateful for Dexcom! of course 2 hours later I required carbs plus protein to manage BG levels. Learning a lot, despite knowing the theory seems I needed personal practice. Thank you for the advice.