The purpose of the study is to compare the human insulin inhalation powder plus insulin glargine with injected insulin (regular human insulin or insulin lispro) plus insulin glargine on lowering the blood sugar level.

Inclusion Criteria:

• Type 1 diabetes mellitus for at least 24 months
• Injecting insulin (insulin lispro, aspart or regular insulin, insulin lispro/aspart mixtures, or regular human insulin mixtures) in the last 24 months
• HbA1c equal or less than 11 %
• Nonsmokers, had not smoked for at least 6 months and agree not to smoke (cigars, cigarettes or pipes) or use smokeless tobacco for the duration of the study
• Satisfactory lung function results to meet the requirement of the study

Exclusion Criteria:

• Previously received any form of inhaled insulin
• Require a daily total insulin dosage greater than 100 U
• Have a current or past history of asthma, chronic obstructive pulmonary disease or other clinically relevant lung disease
• History or presence of liver disease
• History or presence of kidney disease