Since I started pumping I have been using a temporary basal to keep my blood sugars from going low while running. Sometimes it is a little too low or too high but in general if I use 25% of my normal basal amount I will be fairly stable during the run. That is, until I stop. Then a few minutes later it skyrockets with the dreaded post exercise hyperglycemia, except most of the time I am not sprinting or working at 90% effort that it is commonly associated with.
What is happening is as I finish the run my muscles need far less glucose, I am low on insulin and my liver continues to send out lots of glucose. A perfect storm to create high blood sugar.
My strategy is to replace the insulin before I stop running to limit the amount of rise in blood sugar. But I have been conservative until recently and just returned my basal to normal and gave a small bolus 15-20 minutes before I finished. This has limited the rise, but I still could not eat for at least a couple hours. The last couple runs have been encouraging. I have a CGM now and I can be far more aggressive in my treatment. I have been setting my basal to 2X normal for 2hrs and replacing the insulin I am missing with a bolus ( 0.75x(normal basal)x2). Again, about 20min early. I may have been a little over but I am close. I had a couple mild lows of around 3.8mmol/L(68), but I just ate. Also, I could eat without a huge rise in blood sugar. Both times I have kept my blood sugar under 7mmol/L(126). Wooh hoo!!!
This will have a huge affect on my next A1C as these post run high blood sugars are the source of my trouble. I am usually pretty good at being in range otherwise and with a little fine tuning I might be suprising a few people in a couple months.