Steep rise after exercise

Hi everyone,

My first time posting here. I’m a Type 1 (5 years in November), pumping with a Ping, and CGMing with a Dexcom.

I’ve had my Dex for a little over a month now, and I’ve noticed a strange trend. I do a hour long weight class at my gym twice a week. On days when I really work hard, my Dex will show a steep climb in my numbers for hours afterwards, even though my BG is much lower on my meter. My Dex is calibrated correctly, even though this still happens. I made the mistake one week of calibrating when I saw the difference, and dealt with ERR1 for several hours (8 or more) till I finally got it back on track.

Does anyone else experience this? Should I just ride out the high numbers and wait for the Dex to correct itself?


So are you saying the Dex is wrong? I know that when you excersise beyond your norm that the sugars go up instead of down and if this is the case you need extra insulin. If the Dex is what is wrong then I would contact the company and/or keep it out of range while you excersize

Actually after extremely intense exercise such as resistance training, weight lifting or near maximal anaerobic workouts you can experience an immediate rise in BG levels due to hormonal response. Intense exercise causes your body to release epinephrine, norepinephrine, glucagon, growth hormone and cortisol all of which causes the body to release and/or produce more glucose. An additional side effect is an increase in insulin resistance that can last for a few hours. I wonder if the Dexcom is correct and the meter or strips may be the problem.

I agree w/ Phil about the hormonal response and the anaerobic activity. I have noticed this with some of the cycling that I do (crit racing and cyclocross racing push me anaerobic and I tend to increase my BG pretty significantly over a 45 min or 1 hr long race if I don’t increase my basal and/or bolus some just before the race).

But I think both devices could be right. You have to remember that the dex and the tester are measuring two different things. So although your intraarterial glucose may have spiked and returned to normal (what your meter is checking), your interstitial fluid glucose takes time to adjust (what your dex is measuring).

I think Phil and others explained it very well up above. I experience the same thing in that I need more insulin for weight training and high intensity intervals but less insulin for steady state aerobic type activity.

It’s like what happens when you’re sick or frightened or experience other types of physiological stress–a fright or flight response. High intensity exercise causes more of a stress response in the body as opposed to lower intensity activity like aerobic activity. I need to run off right now but later today I’ll see if I can find some articles or references explaining it better.

As Phil mentioned, there are several mechanisms including things like epinephrine, norepinephrine, and cortisol that are released during intense activity. An increase in cortisol levels (among other things) causes an increase in insulin resistance, so it requires more insulin to have the same effect on glucose (example would be correction factor of 1 u to drop 40 points, but in the presence of increased cortisol levels will only drop 20 points, so a better dose would instead be 2 units).
And what Diana mentioned w/ the fight or flight response is pretty much physiologically what is happening when you’re exercising w/ such intensity. The same thing happens to my friend when she gives presentations (which is of course not physical activity). She can start w/ a BG of say 130 and when she gets done it may be nearly 300 unless she takes insulin before her presentation.
In addition to this increase in insulin resistance, when you are exercising anaerobically you are actually not burning your available glucose the same way for ATP production (the thing your body does to make energy). It goes directly into burning fats and proteins b/c oxygen is not required in the same way that it is required when converting glucose. So any glucose that you put on board (by eating or drinking something, for example) will cause an increase in glucose despite available insulin that may be in your system too, only b/c the cells are not requiring that glucose in your blood stream to actually enter the cell (b/c they are getting energy through fat and muscle burning instead).

To the OP, note that if you have wide differences between the meter and Dexcom (and I would recommend testing twice on the meter to make sure the meter value is reasonably accurate) then I would not hesitate to enter the meter value in as a calibration. If you get the ERR1 message, then you need to wait one hour and enter another fingerstick. If it doesn’t clear after an hour, then I would probably kill the sensor and call Dexcom to get a replacement. Waiting 8 hours on an ERR1 message isn’t the recommended procedure. Good luck with your Dexcom.

I am a littel surprised by this but I note( and using CGMS)

a) unless my BG gets punched below 70, I do not see liver activity and higher BG.

b) when I walk, I do not need insulin to transfer glucose as the skeletal muscles have mechanism
to haul glucose directly from blood stream when the local stores are burnt down and one keeps exercising.

c) I find I can haul down my BG walking a mile or two no sweat. There is delay as localcell glucose storage gets burnt down.

d) articles on cell physiology having to due with glucose consumption point out that the direct cell draw will go on even if insulin impaired.

e) only way I get BG to really drop and boot liver into action is very strenuous exercise like the weight lifting.that really burns up glucose fast.