This is a pilot trial to establish study procedures that allow comparison of various starting basal rate profiles used in Continuous Subcutaneous Insulin Infusion (CSII). Glycemic control achieved by circadian 'slide ruler scale' basal rate versus that achieved by one constant basal rate (flat profile) will be compared during a composite fasting day as well as therapeutic success after 2 weeks of normal activity.

Inclusion Criteria:

• Adult patients >= 18 years of age
• Type 1 diabetes
• Diabetic for >2 years, and treated with CSII for >= 3 months
• HbA1c <=8.5%

Exclusion Criteria:

• Excessive fibrosis or lipo-hypertrophy at injection or infusion sites
• Unstable chronic disease other than type 1 diabetes
• Severe hypoglycemic event within last week prior to study start
• Severe diabetic ketoacidosis within last month prior to study start