Blood sugar before exercise

Suppose you know that your bg needs to be 150-160 to make it through an exercise session without going low. If you exercise 2 hours after lunch, does it make a difference if you adjust your lunch ratio such that you’re at 160 at the 2 hour mark versus setting your ratio such that you’re 100-120 at the 2 hour mark but then have to eat something before exercising to get your bg up to the proper range to sustain your exercise session?

Thanks for your thoughts.

I'd rather do the 120 and "fuel" as I think that it will help your performance to have something like Gatorade for performance/ hydration, maybe whether you have diabetes or not.

I don't intentionally run my BG up before I run. I won't let an accidental high get in the way of working out but I usually run up to 120 before I workout, if I'm planning a longer workout. If I'm doing a shorter session, I'll just cut it short and don't usually worry about it as shorter, anaerobic types of exercise seem to boost BG a bit.

This is what has worked for me . I notice that the best time to exercise is within an hour after the meal because then you can use exercise to bring your sugar down . Here’s an example yesterday my bl was 83 before a breakfast of about 40 carb, so what I do is take about 1/3 of what the pump tells me to take ( if it says take 2.5, I will take only 1.3) then I feel confident that I will be able to do the elliptical for an hour . Usually at the 55 minute mark I start to feel a low come on and all I do is start drinking my bottle of apple juice that is right next to me in the cup holder . So yes for me I am happy with a good strong hour and I accept that in order to stay perfect threw out exercise I will go low . But the low is never a scary one cause as long as I start sipping that juice right away the feeling starts to go away with each sip ( not even exaggerating )

I like to be around 120-130 before exercise and unlike AcidRock I prefer to allow my blood sugar to reach that level 3 hours post lunch without an extra snack. Of course, my exercise is only 45-60 minutes of walking rather than anything more demanding which probably makes a difference.


well...I like my BG to be 100 2 hours after lunch but, if the "tail" of the insulin is still lurking around, I'll snack on top of that before I run? ;-)

Is it just a matter of personal preference or do you think one way is better for your body than the other?

My son has gotten really good at knowing where he needs to start to sustain various workouts, but we’re just wondering if it makes a difference how he gets there, whether with a snack before working out or from staying somewhat elevated after lunch. Since he is at school, he doesn’t have any control over what time he eats lunch or what time he has athletics class.

We’ve experimented with both methods. Lately, he’s going through yet another growth spurt and is always hungry, so he’s happy to have a snack before he works out.

Thanks for chiming in everyone!

One more thing… Due to the timing of lunch vs. athletics class, he does still have that tail of his insulin lurking around at the time he starts athletics class.

Does his gizmo show IOB? If it does, I test, check IOB and eat accordingly, really it depends on the numbers how I'm feeling. PE would be tough b/c you never know what the teacher's gonna dish out..."run laps" vs "talk about the birds and bees" will be two different plans!

PE is tough, especially during “off season”. The coaches say they have a plan, but they only follow it occasionally. Then, invariably, some kid will smart off or leave his towel on the locker room floor and they spend the whole period having a group punishment which might be wind sprints, pushups, wall sits, etc.

His pump does show IOB, and he takes that into account along with his current bg when deciding what/how much to eat. He’s gotten pretty good at all this and just rolls with whatever the day brings. He’s not having bg problems during class fortunately. If there’s a problem, it’s usually after school.

Jay Cutler said he aims for 120-180 but I find that I don't feel that well run it runs high, although that may also be b/c I'm sort of high-strung about my BG? I think that your body needs some "fuel" (e.g. the 3 brands of gatorade, G1, G2, G3??) and I'd rather have some fast acting, "short" carbs "on board" instead of "eating" the tail of lunch although really, I think that some of both is good.

A lot of runners use that "Gu" and other brands of gels but I've noted most of them use maltodextrose that "deploys" slowly. If I have one 7 miles into a half-marathon when they are passing out "freebies", my bg spikes after the race (I run about 2 hours for that distance?).

I am not a scientist or doctor or anything like that but in my (2 years of running that my control has been generally pretty good, with adventures, of course!), I've found that I feel like I run best with more frequent, small doses of fast-acting carbs than "one big hump" and burn it off. I had one run where my pump failed last summer and another one where two sites sweated off (it was really hot, but not Austin hot...) and both times, when my BG got elevated, I felt like crap and had a really hard time running, a lot of cramps.

For basketball, he needs to be around 160. He literally will drop 40-50 points within a few minutes of starting to play even with no bolus insulin on board. It’s crazy and has been scary a few times.

For running, he tends to stay pretty stable and might even go up a bit, so starting around 110-120 has been working well. If he’s running a race (cross country or a 10K, not a sprint), he’ll shoot up while running & will drop after. He’ll also boost his basal a bit if it’s a longer race then will eat or drink gatorade after and reduce or eliminate his bolus, depending on the situation.

If he’s running, he has a bit more control and can carry fuel with him. If he’s in the middle of a basketball game, he can’t really stop & eat. He has Gatorade with him, but if he’s playing hard, he doesn’t want anything sweet. He also doesn’t want to stand out as the team diabetic, so he likes to be extremely discreet when it comes to sports. We live in an area with crazy good athletes, and he’s just regular good. He doesn’t want to do anything that might draw attention to himself in a negative way and put any doubt in a coach’s mind that he should be there.

So, to your way of thinking, get the bg where we’d like it following a meal, then refuel as needed - don’t allow the bg to stay high enough to fuel the activity?