This is a 6-sequence, 3-period (8 weeks each), 3-arm, 24-week crossover study. The purpose of this study is to provide information on the use of insulin lispro in insulin pumps (Continuous Subcutaneous Insulin Infusion [CSII]) compared to insulin aspart over 6 days of pump reservoir in-use. The study will also compare the in-use characteristics of insulin lispro infused at 6 days with insulin lispro infused at 2 days.