Blood Sugar Control and Running: Still A Mystery


Since going on the pump I’ve been trying to relearn my body and the way it burns sugars while I run. I did an experiment like this once before when I was training for the 2011 Tiberias marathon (a year ago).  At the time I was injecting insulin (MDI). It took a while but within a few months I had it down to a science, well may be not a science, but I was very confident and didn’t feel like I needed to check my blood sugar during races.

Now, since going on the pump, I feel as if it is totally random and chaotic. Sometimes my blood sugar plummets within 3 miles and sometimes it just won’t come down.

Although I’ve been training hard and checking my blood sugar during my runs, I still don’t feel as if I’m on top of things. I’ve run a few shorter races without checking (10k and 15k), but in short races the price for messing up is usually paid for only after the race is done. A marathon, or even a half, is a totally different story.

On Friday, I ran the Beit She’an Half Marathon for the 3rd time. Well, I actually ran 20 miles – 7 miles at an easy pace before the race began and then 13.1, the half marathon. The extra miles were an attempt to make up for a lack of miles and long runs in the past few weeks due to injury and a cold and with only five weeks left until the Tiberias marathon I felt I needed a 20 miler.

I woke up at 4:45am to get ready for the race. I checked my blood sugar and it was 157. Too high for a regular day but good for race day. I had some coffee and got ready for the trip (about an hour and a half without traffic). I left at 5:45, picked up a few people on the way and drove toward the Beit She’an valley.

The race was supposed to begin at 9:15 so I decided to set out at 8:00 for my extra miles. (At 7:00, while driving I remembered to reduce my basal rate to 30%.) We arrived at the race area a little late because of race traffic, but early enough to not mess up my plan. I checked my blood sugar again. It was down to 138. I got myself ready and at 8:00 I was out running. After 3.5 miles I checked my blood sugar thinking it was time to take an energy gel (usually my BS starts to drop at this point) but my blood sugar was 140. I decided to just continue running. I arrived back at the starting area at 8:50 with plenty of time to get myself ready.  I checked my blood sugar again, thinking it was definitely time for a gel, but my blood sugar was still 140.

I couldn’t, and still can’t, understand it. I checked again 15 minutes later. I was sure my blood sugar would be dropping but the glucometer said 165. I didn’t know what to do. I took out an energy gel from my pack and decided to take it at the first water station (3 miles away).

The race started and I found myself running at faster pace than I had planned.  Like in my last race I tried to slow down but kept on running at a pace that was 10 seconds faster per mile than planned. I reached the first water station but was too scared to take my gel thinking it may cause my blood sugar to spike. I waited two more miles and then decided to take my first and only gel of the race.

At the 5th mile we turned on to an open road with fields on either side. Last year this was a very enjoyable part of the race but this year there were no clouds and a strong headwind to fight.

I continued to run at a steady pace, the same pace I started with, not letting the wind, or extra miles slow me down.  

The course is pretty flat for the most part except for one section. At the 10th mile there is a steep descent downhill which is followed by a long and grueling climb back up. The downhill was nice and quick but the climb was a breaking point. I knew I would have to slow down during the uphill part of the race, but thought I would pick the pace back up when it flattened out again.

That did not happen. The lack of energy and the extra mileage had taken their toll and I just couldn’t get back to a good pace. I tried to save some energy thinking I could finish strong when I came to the last half mile but that didn’t happen either.

Although I was not happy with my performance I set a new personal record, 1:45:12, running 3 minutes faster than my last half marathon.

I checked my blood sugar after the race and it was 109. I realized I had made a mistake. I should have taken another gel. It would have given me the energy I needed during the last few miles of the race and would probably not have sent my blood sugar too high.

All this has made me worry about my readiness for my upcoming marathon. I am in better running condition than ever but as far as diabetes is concerned I feel less prepared than ever.

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10 years ago

The problem with a pump is the consistent site location and the constant drip of insulin. The moment I get up and going, insulin can enter the bloodstream faster. In fact I will have high blood sugar until I give the site a bit of a massage, then it is a quick hit. Compared to Lantis, the reaction is very different. It seems that exercise was quick to take me to a low. However, instead of 30% or lower, I just turn it all off for a couple of hours. On the other hand, when I did running or very… Read more »

Jessica Apple
10 years ago

You’d laugh less if you heard the alarm clock beeping before dawn :).  He’s crazy, but I love him.

Catherine Price
10 years ago

Thanks Karmel. I do most of my running at 5:00-7:00 in the mornings but races tend to start later. This morning I ran at 5:30 after a mile and a half my BS was 78 (it started at 138) so I took a gel. 3 miles later it was 59 – another gel. 
I have no explanation for the changes. 

Dr. Margaret A. Morris
10 years ago

It strikes me that one of the hard parts is that, if you’ll allow a perversion of the Heisenberg Uncertainty Principle says, the mere act of observing your blood sugar changes its value. More precisely, I imagine the stress and break-in-stride of measuring your BG while running actually has a non-neglible effect on your BG. I don’t have a solution for you, so much as commiseration, and maybe the suggestion that if you can make everything as routine as possible, it might be easier (i.e., run at the same time, measure BG at the same interval, make sure the weather… Read more »

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