When is the optimal time for exercise for iddm using 100 units daily of both humalog (insulin lispro) and lantis?

Basal or Adj insulin. Best time is when only your basal Insulin is on board, to reduce risk of lows. If that doesn't fit ur schedule, u may have to take a negative correction for the dose of Humalog (insulin lispro) that precedes your exercise, ex. Cut down lunch Humalog (insulin lispro) if exercise at 1:30pm. The amt to reduce varies bet'n ppl; exercise, chk before and after so u know ur bg response, and can better guess how much Humalog (insulin lispro) to subtract.
Any time. Exercise is so important !, any thing you like any time you want. Juggle your Insulin around it. You may want to start with a regular routine till you get the pattern of your bodies Insulin needs figured out. Take notes!