I just posted this at my blog, with a pretty serious question about what you all do about lows and preventing them during exercise…
Strenuous exercise sends me high & crashing later, so I’ve opted for more moderate exercise. I do a lot of walking. Hilly where I live. And I also use weights.
Wonder if something was going on that you were particularly insulin sensitive to be consistently that low. Does this happen often from exercise? Did you happen to inject in your leg? I did that a couple of times before a hike & insulin hit hard & fast.
What I do is eat some jelly beans before exercise & then a small amount of protein. Each one has 1 gram of sugar so easy to control amount. I hate glucose tabs & they’re bulky to carry around. Trial & error to see how many jelly beans I need. I raise my BG 30-40 pts, depending where BG is, before exercise. Slight boost in BG & the protein helps keep it level. I test frequently during exercise & treat with more jelly beans, if needed.
Levemir takes about 2 hours to start working, so that shouldn’t have effected you if you had taken it.
Hi - I too experienced lows during exercise, so i adjusted my LANTUS by reducing it from 12 to 8 units… That I take right before bedtime.
and always eat 1/2 sandwich (which equates to 15 carbos) about 30 min before starting. My workouts typically last 1.5 hours — cardio and weight lifting (I"m a gym rat 
) If I’m running around 110 or so, I will drink a muscle milk instead of the 1/2 sandwich (which equates to 10 carbos).
The key is to get yourself up around 125-135 before starting the workout!