Both @Eric and my son faced severe post-exercise lows this evening, due in both cases to a change in exercise regimen without a matching change in basal insulin dosage. Eric went through 60 grams of carbs before going up, while my boy went through 47 grams, in a 2.5 hour sustained low.
In the process, Eric and I wondered how much glycogen might be available in the liver 6 to 7 hours after exercise, at a time where either may have needed a glucagon injection – would there be enough glycogen to help bring BG up?
We did some quick research to figure this out. If we assume exhausting exercise that fully depletes glycogen stores, assuming that we have maximized replenishment by taking carbs and protein right after exercise, and by taking carbs frequently afterwards (ideally every 15 to 30 minutes), after 6-7 hours (i.e. middle of the night for a late afternoon exercise) we would expect the liver 30% replenished: probably enough for glucagon to be effective.
As a note, btw, something I discovered recently – glucagon won’t work if you are drunk: the liver won’t dump in the presence of significant quantities of alcohol.
You can find a more scientific summary of this investigation on the wiki we made with the research:
Glycogen replenishment after exercise: science and timing