How long is the shortest workout you have done, resulting in a visible drop in your BG levels?

We are looking at the duration of the Big Blue Test. On it we ask participants to test their BG before 14 minutes of exercise, test again and share the experience.

In 2010, we saw a nearly 18% drop in BG levels after 14 minutes of exercise in connection with the Big Blue Test. I would like to know if workouts as short as 10 minutes have made your BG levels drop visibly? What kind of exercise did you do?

What is the average duration of a workout that you do, during which you see a visible drop in blood sugar?

I have had drops as quick as 10 minutes into a workout, but it is more about intensity than duration. I was running

Plus, I was likely a result of doing a correction and underestimating the effect of the bolus

I swim, bike and run and find that if I need to do a correction prior to working out, I need to adjust my bolus back by 75% if the exercise is going to have a high intensity level.

On Group bike rides where I maintain a high steady speed for example, I don’t need to refuel nearly as soon or as much as when there are a lot of attacks driving me up into the red zone of my heart rate. Rides with a lot of climbing affect me in the same way.

LIkely because I am spending significant amounts of time past my lactate threshold, which once exceeded causes energy use to climb 5x and we are working more off of our BG than our metabolism. I have been playing around with this a lot lately because of lows ruining my workouts and causing me to cut them short (mostly with running as I usually do this alone)

a few weeks ago, I did a 165 mile single day ride and while I drifted a little on the low side 5 hours in just prior to lunch,(80) I was pretty steady all day long (actual ride time was 10.5 hours) i started the day with a bowl of oatmeal and 2 apples, consumed consistently 17 carbs per hour through my electrolite drink and had 2 bananas, had a 6" subway for lunch, had to eat a GU pack 4 miles from the finish do to a bit more serious low 60. But I tried very hard to keep my heart rate down all day (I averaged 116) so that I could work mainly off my metabolism and not have to worry so much about making BG all the time. (also lowered my basal to 50% before the start and planned on 10 hours, so it had kicked back up again when I had the low as my actual travel time with stops was 11.5 hours)

It seemed to work really well aside from that little hickup at the end that was likely to much basal.

So the quick drops that I have had, have all been on hot days (less time to warmup before intensity) sometimes with an abreviated correction on the front end

Sorry for the book, but this all seemed relevant to me :slight_smile:


Mine goes down with 10 minutes but I can’t say that it is visible. I have been having some fatigue issues lately and have only been doing 10 minutes on the treadmill (and I can’t go fast because of neuropathy). I will test it tomorrow and let you know. I usually do it in the AM and that is more fighting to keep it down time but if I do it after lunch, it will go down.

10 minutes into cardio workouts my sugar drops…
Anaerobic exercising/weight lifting raises my sugar slowly

I used to run up and down the stairs 10 times. I don’t think that it would even take 14 minutes but it would nudge them down. That was during my R/N days though so there may have been all sorts of stray insulin floating around too…

About 6 minutes. I had walked to the corner (130 ft, then around the corner another 40 ft.) after I heard a car wreck, then walked back to the house. I had dropped almost 60 points according to my cgm. It was also during hot weather.


Exercise raises my blood sugar. It doesn’t matter whether it’s gentle exercise like moderate walking or intense aerobics, doesn’t matter if it’s 15 minutes or an hour. I always go higher than I was before the exercise.

Grocery shopping is the worst. I have to really watch myself when I go grocery shopping or I’ll be in the last check-out line (I go to three stores) and feeling just awful, check, and I’m 180-200. That’s after leaving the house at 110.

Hi Manny,

Interesting theme, because Pancreum intends to have a feature for exercise in its bolus calculator.

We intend to also ask “Are you going to exercise?” before suggesting an amount. If so, the user will select from “1-Light 2-Mild 3-Average 4-Heavy” and then the calculator will deduct a certain amount of insulin from the suggested bolus.

We may have to ask the user to first go to “Settings” and enter those amounts to deduct or even their each level preferred text names.

We think it depends a lot on the intensity, as well as time and each person fitness level, weight, etc. So those numbers are though to estimate, and that’s why we’ll probably have to ask the user to enter the deduction amounts.


10 min, down 40 mg/dL. from 100 to 60, no short acting insulin in me. Treadmill at 4.0.
I would like to see responses in relation to weight of the person, too!

Great summation! I agree that intensity is far more critical than duration. Of course they are both important, but it is possible to drop BG dramatically in a very short duration through high intensity.

I did 10 minutes on the treadmill at 2.0 MPH (Leo is twice as fast!). I went from 189 to 158 – about 30% drop. About a half hour before getting on the treadmill, I was 173. Today has been a rollercoaster day though so the drop could have been part of the rollercoaster ride I have been on.

I generally disconnect when going to the gym. I’m usually only in there for less than an hour so it’s generally not a big deal. Depending on what my blood sugar is doing though, I may give a bit of a bolus. I generally only weight lift at this point so my blood sugar actually goes up. I don’t have any numbers, that’s just been the trend I’ve seen. If I’m doing something more steady and active, such as playing tennis or yard work around the house, I usually see it creep down in about 30 minutes.

Once I had 9 point something (162 if I did the math correctly) and after I’d worked out for 10-15 mins I started feeling a bit woozy and I had 2.8 (50.4). I don’t know if it was just something about that day but now I always eat a biscuit before working out if it’s below 10 (180).

My blood sugar generally does up when I do exercise.

I had a sense , the reason why 14 minutes of exercise is mentioned in the Big Blue Test …is related to the Birthday of Dr. Banting ( November 14 ) ; I never took it literally meaning doing 14 minutes of exercise and that’s it …then stop !
I would think , that there are millions of reasons ( so to speak ) why the answer to the question of this discussion will be so different …even for me from one day to another .

wasn’t there a Big Blue Test Thing where you were supposed to test, exercise for 14 minutes and enter the drop or something like that? 7:30 is about the fastest I’ve run a mile so I don’t think I can quite get two in that timeframe but it can be fun to do wierd experiements like that?

15 minutes, how annoying is that how can you loose wight if your always shoving carbs into your gob!!!
Am a swimmer, I have not worked out to manage the non-hypos after a few laps of the pool. Ellaxx

7 minutes is the fastest I’ve had. I was 350. Danced to Jai Ho, dropped to 287. I’d done half a correction before dancing.

My BG goes up; only incrimentally but it does go up. I am just starting my exercise routine, I’ve been walking 2 miles a day, 3-4 times per week plus Zumba twice a week for an hour. Walking pace is about 14 minutes per mile. I have seen a 5-10lb weight loss since my dx in the first week of June, 2011. I fluctuate between 3-5lbs any given day.

I feel lightheaded and somewhat dizzy sometimes when I’m exerting a lot of energy and I just “know” I’m low–turns out I’m much higher than I suspect.

I am a newly dx’d T1, NOT on the pump.

Last night, I had some pizza. At the 3 hour mark I was 225 (apparently I missed the carbs by a unit or so.) I got pissed, put on my shoes, ran/walked about 50/50% of the time.I got back to the house and only 15 minutes had gone by. Tetsed and it was 103.

So about 120 points in 15 minutes worth of cardio.