Never Take Insulin Before You Run


I have eight weeks to go until the Tel Aviv Marathon and I’ve been training hard. I feel good and I’m faster than I was a year ago when I set my marathon record

For the last couple of weeks, though, my long weekend runs have suffered from diabetes issues. For some reason, I’ve been waking up with relatively high blood sugar (220-250), which doesn’t come down during my run. Last week I ran well for 18 miles but then, after taking only one energy gel during the first part of my run, I slowed down and ran the last 2.5 miles at a slowing pace until I just stopped half a mile early.

Yesterday, I woke up early for my run sure that my blood sugar was fine. I had even set an alarm during the night to wake me up to test. I was 190 during the night so I bolused and went back to sleep for a few hours.  But when I tested my blood sugar a few minutes after waking up, at around 4:30 a.m., it was 223 and I was shocked. I got myself ready to go running hoping my blood sugar would come down a little before I had to go. I didn’t lower my basal rate either, thinking it would help bring me down to a decent level. A half hour later I checked again. This time it was worse  – 243. I was annoyed and worried. I decided I would do what I never ever do before a run – I bolused. I plugged the number into my pump, which recommended I take 2.8 units of insulin. I decided it would be safe to take half that amount.

A half hour later I was ready to go. I checked my blood sugar again – 222 – and reduced my basal rate. I ran two miles and stopped to check my blood sugar. It was 142. I noticed that it had dropped quickly, but didn’t think much of it. I continued running and stopped again 5 miles into the run. I drank some water and checked again. This time it was 54. I couldn’t believe it. I checked a second time. The meter read 63. I tried not to panic. I was running well, feeling strong but I knew that it could all be over in a minute. I took a gel and kept on going. 

I ran another 2 miles hoping I had caught  myself early enough to save the run. I checked my blood sugar – 99. I continued for three more miles and tested again – 90. I decided to take another gel.

I continued for 12.5 more miles, checking twice more and taking another gel, and feeling great. Tired but great.

I ran 22.5 miles in 2 hours, 55 minutes, and 30 seconds, and felt like I could have run another 3.7 miles (that would make 26.2 aka a marathon).

After two bad long runs and a near disaster I finally ran a long training run that made me believe a new personal record is very possible. I just need to keep training, not get injured and keep my blood sugar under control.

I also have to remember to never take insulin before I run. Never.

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8 years ago

I know exactly what you mean. But never say “never”. I had the opposite experience. I thought, after 3 marathons and 3 lows in the first 5K that the next time I would simply refrain from taking any short-acting (bolus) insulin, but let’s just say that my blood sugar climbed before the race, and then the race was actually delayed and it climbed some more. I got to 8K and my blood sugar was 20mmol! I didn’t have any insulin on me and do not use a pump. With the blood sugar and the exercise actually forcing my blood sugar… Read more »

Catherine Price
10 years ago

Hey Scott,
No I don’t wear a CGM. I’n not covered for it. I wish I did. It would probably make life much easier.

I’m not sure what been up during the night but I seem to go through periods where my body needs less insulin, I have more lows and I don’t wake up very high and then suddenly my body becomes more insulin resistant, or something, and my numbers are much higher. 
The interesting thing is that is has nothing to do with how much I run. 

Scott K. Johnson
10 years ago

Glad your run turned out well! 

I forget, do you use a CGM? Any thoughts on what’s happening at night? 

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