Sugar

So make sure you eat before you go?

Are you a diabetic? If so, have you been referred to a certified diabetes educator or registered dietician?

There's quick ways to bring up your BG prior to exercising (my endo wants me around 150-200mg/dL prior to exercise with the anticipation that I will be dropping, but I instead shoot for around 100-120 and modify my insulin/carbs consumed to keep myself steady during exercise). Have you tested to see how much your BG will rise if you consume so many grams of carbs? For instance, if I eat one glucose tablet (4g of carbs), my BG will rise on average about 16mg/dL (4mg/dL per 1g of carbs). Using that information, if prior to exercising my BG is 80 (and I want it to be 110), I will consume about 8g of carbs, or two glucose tablets (110-80=30mg/dL difference. I then divide the 30mg/dL by how much 1g of carbs raises me, 4mg/dL, to get 7.5g of carbs. I like to remain conservative and will round up so that I'm eating more).