History of diabetes mellitus Previous exposure to any inhaled insulin product Any known pulmonary disease or inability to perform PFT maneuvers meeting recommended American Thoracic Society (ATS) standards of acceptability and repeatability criteria Respiratory tract infection within 8 weeks prior to Screening/Visit 1 Major organ system diseases including seizures, heart failure, uncontrolled hypertension, aneurysm, cancer within the past 5 years, liver disease, anemia or autoimmune disorder Clinically significant abnormalities on screening laboratory evaluation Female subjects who are pregnant, lactating, or planning to become pregnant during the clinical trial period or not practicing adequate birth control Unable and/or unlikely to comprehend how to use the investigational device in this study or to follow study instructions