How much - what do you all eat before a sustained time at the gym?

So my trips to the gym of late have been frustrating, because if I don't eat something with some carbs in it, I go very low (like 50), but in order to avoid the low, I eat fast acting carbs which seems to defeat the purpose of the exercise - losing the extra weight I'm carrying around.

Any suggestions on how to balance this?

An apple or a banana before the workout isn't doing it.

I still go low

I do 30 minutes on an exercise bike, followed by 30 minutes on a treadmill, and then some weights to build up my knee (recovering from arthroscopic surgery)

One suggestion is to treat your lows as they happen with only sufficient carbs to treat the low. A roll of smarties is like 6 g of carbs and each tablet is 0.4g. That enables you to control exactly what you take in to treat the low.

The other thing you might consider is that some exercises may raise your blood sugar, others lower it. For me, weight training makes my blood sugar soar, so you could do weights first.

Weird that weights would make it rise - maybe the body knows whats up, and wants to give the muscles the goods?

My problem with letting myself go low and trying to come out of it is that I seem to get very exhausted coming back up to normal. Once I come back up to 100 or more from being down at 50, all I want to do is sleep.

Do you have a calibration on going up - as in how much g of carbs it takes to get your levels up a certain amount?
Its been a challenge figuring out how much insulin I need to come down - my ratio changes during the day

bsc has some great advice. weights also bring me up a bit. The amount of carbs/bg unit is usually very individual and needs some trial and error.

When do you exercise relative to your last insulin dose? In general, I won’t exercise for 3-4 hours after I have taken any significant amount of fast-acting insulin because my sensitivity changes so much. That can mean some gymnastics with meals. When I can’t exercise immediately following a meal, which is my preference, then I will eat protein/fat at meal time and hold the carbs (usually 30-40g in a meal) until right before I exercise (for which I typically take no bolus insulin).

If you still are going low despite eating beforehand you should probably ingest carbs during exercise, too. Try using a sports drink instead of water while you're on the cycle and treadmill. Sip liberally throughout your workout. Smarties and glucose tabs are also good ideas.

You can also eat more carbs before exercising. Try Clif bars- 45 g - available at most sporting goods stores and at Costco. Half a peanut butter sandwich with a half glass of milk is also good. For me. As Tom T suggest, don't bolus for these carbs if you'll be exercising within an hour or so. At least reduce your bolus - I reduce mine by 1 unit per 30 minutes of planned exercise.

Aerobic and endurance exercises tend to drop BG because your body is using up glucose. Anaerobic exercises like weight lifting or sprinting tend to raise BG because your liver dumps glycogen into the blood, perceiving an emergency need for more energy right away. (That's a very simplistic explanation.) But weight lifting will often only raise BG if you're doing heavy weights and low reps - light weights and low reps less so because it's more like aerobic exercise. I would recommend adding the weight lifting BETWEEN cycling and the treadmill.

Keep trying different things until you find what works best for you. There's no single answer that will work for everyone.

There's great information about exercise and blood sugar in the Diabetic Athletes Group here, where this subject comes up all the time or in the books Think Like a Pancreas or The Diabetic Athlete.

Good luck,


I like Starburst Jelly Beans. They are extremely tasty and convenient as I got some little bags @ hobby lobby and measure them out. They are close to 1G of carb each, like Skittles but I find them easy to eat? If I'm not running out of gas, I will just keep an eye on my CGM and hit them every once in a while, like 10 every 3 miles? I agree that everyone is different. I also have noticed that when I get used to exercising, my need for carbs/ lowering insulin seems to go down? I ran a lot last winter and by the races I ran in the spring (2x 1/2 2 weeks!), I was only turning my basal down to 40%, instead of 15% like when I first started running longer distances? Then, when it got hot, I switched to biking and ended up turning the pump off b/c I was running lowall the time, although it's easier to lug carbs on a bike? I also have pumped up my BG, on longer runs when i ran low on carbs, by sprinting hard?

If you don't want to ingest an entire bottle of gatorade or powerade, you might want to try the Gatorade prime that comes in a pouch. It's labeled "pre game" fuel and has 25 carbs in it at about a fourth the size of a Gatorade bottle. Depending on what my BG's are going into a soccer game, I usually down one of these.


Another good idea w/ Gatorade is to get the powder as 1) it is cheaper, like $2.99 or 3.99 makes the 5 gallon bucket you dump on the coach and 2) you can mix in however many carbs you need? If you are running, it will shake it enough to absorb at least double or triple strength although you can also make a 1/2 strength model if you want to hydrate w/o too many carbs? If you have a scale, you just weigh the powder right into your bottle. If I am going for a longer bike ride or run, I use an Amphipod belt to hold some high octane to use if I run lower and then less carby just to drink. I think that going for an hour like that, it would be pretty important to hydrate at least every 20-30 minutes? But it's good to have some diversity. I agree w/ Michael that a whole bottle of Gatorade would likely be too much? I think 10-15 carbs/ 1/2 hour is about right. That's about the interval between hydration stations at most longer races?

Anaerobic activities - ones with short bursts of energy such as weights - produce a surge of adrenaline which makes the liver release glucose. Later in the day (for me it's two and a half hours) your sugars come down. To counteract the effects rethink your eating habits and insulin dosing. When I do weights I eat a bowl of cheerios (regular, 1 cup cereal and 1/2 cup milk) and a 1/2 cup skim milk to drink. Normally I'd take 3 units to cover this but on a workout day I drop it to one unit. The reason being that your body is most efficient at sports and exercise between about 160 to 220. Assuming I start breakfast around 120 the insulin will only allow the carbs to raise my sugars to 160 or so. My raise at the gym is approx 30 so I run right in line for where I should be for weights. Of course you will be different, but you get the idea. The only way to figure this out is to test, test, test. When I started working out I tested every half hour and plotted what was happening. This was before breakfast, before working out, during, and for several hours after. It's expensive, but if you can collect three days minimum of data from your workouts you'll save money in the long run and your weightlifting workouts will be much more productive (also, when you do weights with your sugars in that sweet spot you get additional testosterone and adrenaline pumping which lets you do more than you can!). Just keep in mind you also need to learn how far out you will drop. And eating a high protein immediately after working out helps build your muscles which lets you do even more!

The info on the sweet spot and other info is from Think Like a Pancreas. It's an outstanding book and has excellent information on exercise and insulin therapy.

I'm T1. Serious exercise usually sends me high & then low hours later. I eat protein before major work-outs to help things stay level. I haven't had success trying to carb up before. I stop, test & treat lows (rare for me, but it happens) with jelly beans.

I'm small so not a good comparison, but 1 gram glucose raises me 10 pts. Was trial & error to figure that out. When slightly low, I took 1 gram fast acting glucose (nothing with fat or protein) & tested at 30 minutes & 60 minutes to see the full effect. With everything that keeps changing, that's one factor that has stayed constant for me.