I've been re-reading Think Like a Pancreas. One of the "new" things that I came across was that Gary Scheiner says that hard effort exercise can show it's effect on your glucose levels much later, sometimes 12 or more hours later.
Yesterday I took some students indoor rock climbing, and I worked pretty hard. During the event my levels were a bit higher than usual... adrenaline, surges of glycogen, etc. Sore forearms and everything. Lots of fun and challenges.
Well, overnight my blood sugars were fine, but this AM I have been running low all day and have had to eat some candy twice to keep myself in the comfortable zone. My glucose has been under 90 all morning and dipping below 70 at times. No bolus at lunch. He described his experience with this almost exactly the way it has gone for me today. If I hadn't read that recently, I would have thought it was witchcraft.
I also had some Yerba Mate tea this morning? Hmmm. Maybe something to that theory too.