Everybody else has been SO helpful haven't they.

My opinion. I'm in UK so units may be a little wrong if you're in the States.

I take 28 units of Insulin glagine which is the long acting stuff. If I were to take much more then I'd wake up in the morning very low and probably find it very hard to get myself at a good level again. i could probably handle 5-8 units more than I usually take I'd say 10 was an overdose.

Short acting stuff depends what you eat. I take Insulin Lispro. I'd have about 4 units before a main meal without a sweet (chips, chicken and veg) say about 40g carbs, if i was to have 6+ I'd consider that an overdose and would need to have something extra.

As you say, it all depends on what you're eating, what exercise you're doing and your individual regime.