Exercise Resistant Diabetes


This morning I ran 6.5 miles at a 7:20-7:30 pace, 15 seconds quicker than my target marathon pace. I ran a 4-mile warm up, checked my blood sugar – it was 130 – took a gel and started my run. I ran the 6.5 miles without stopping and although the pace wasn’t supposed to be hard for me, it was. When I was done I checked my blood sugar again and it was 172. 

On Thursday morning I am running my last long run before the marathon.  The fatigue I felt during my run this morning doesn’t bother me so much, I imagine that it’s a result of all the hard training – Friday’s half marathon and that fact the I ran intervals yesterday.

What’s bothering me, really bothering me, is my blood sugar.

When I finished my run this morning I expected my blood sugar to be somewhere in the vicinity of 100 or at least back to where it was when I took my gel. That would mean that during a long run, or a marathon, this would be the time to take another gel. In all of my past marathons, and during training I took a gel every 6-7 miles (40-50 minutes). That routine kept my blood sugar between 130 and 200, and kept my body fuelled.

But now it’s as if something has changed. I run 10 miles and my blood sugar doesn’t seem to go down at all. During the half marathon when I stopped to check my blood sugar, 5 miles after my only gel, my blood sugar was 187.

You could think that this was a good thing – not going low when I run, but it’s actually a disaster. If my blood sugar doesn’t go back down after 6-7 miles I can’t take gels and if I can’t take gels, I won’t have the energy needed to keep up my pace.  I might not even have enough energy to finish the race.

This has made me very nervous, especially because I’m running out of experimentation time. If I had a little longer I might try playing with my temp basal rate, setting it at 40% or 50% instead of 30%. But I’m too scared to try anything like that now. So I guess I’ll run my last long run sticking to what has worked in the past and hope that all the pieces fall into place.

Right now, it feels like my diabetes has become exercise resistant. 

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10 years ago

I can’t tell you how glad I was to find this…not that I’m glad you’re having trouble, but I’m in almost the exact same situation and was wondering what in the hell is wrong with me. I have my marathon in 2.5 weeks and my training runs the past week are having some crazy impacts on my blood sugars. I ran 8 miles this evening and ended up much higher than I started, even without the gel that I normally would have had half way through. Same deal with my 20 miler this past week.  I’ve read that as your… Read more »

10 years ago

Whenever I run at a slightly faster pace than usual (so for me 7:45s rather than 8:00s), my bg ends high.  I interpret it as my liver saying, “wow, she is really working hard, i’m going to give her some sugar to fuel that!  Not of course being aware than my pancreas is no longer pumping out insulin to help that sugar get into my muscles and be of any use.  It does not solve the problem, but that is how I explain it to myself.  And it is pretty consistent. 

Jane Kokernak
10 years ago

Often when I read your posts about unexplained high or low BGs, I wonder if you’ve done the fasting basal tests. Admittedly I don’t do these as frequently as I should, but it’s the only way to check if your basal rate is really giving you the right amount of insulin (without boluses for food, without temp basal rates for exercise). It could be worthwhile doing that before the next race: http://www.integrateddiabetes.com/p_basaltest.shtml  My endocrinologist always suggests doing one when I have a pattern of high or low BG that defies explanation with what I’m eating or bolusing.

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