To determine in subjects with Type 1 Diabetes Mellitus:

1. Whether glycemic control can be achieved at least as effectively with a) an intensive insulin regimen involving pre-meal inhaled insulin plus twice daily subcutaneous NPH insulin as with b) an intensive subcutaneous insulin regimen involving pre-meal regular insulin plus twice daily NPH, given as 4 injections per day. The treatment regimens differ only by the route of delivery of the short acting insulin.
2. The toleration and safety of inhaled insulin therapy and its effects after 6months, if any, on measures of pulmonary function.

Inclusion Criteria:

• Type 1 Diabetes for more than 1 year
• Stable insulin regimen of at least 2 injections per day

Exclusion Criteria:

• Any smoking within the last 6 months. Smoking is not permitted at any time during this study.
• Subjects on insulin pump during 2 months prior to screening.
• Subjects with poorly-controlled asthma, clinically significant chronic obstructive pulmonary disease, or other significant respiratory disease.