Subjects will be asked to provide a recent negative COVID-19 test (if available), confirm they have no symptoms of COVID-19, or provide evidence of COVID-19 vaccination.  Inclusion Criteria:  Subjects ≥18 years of age at the time of signing the informed consent form Clinical diagnosis of T1DM or T2DM (per the Investigator) and on a stable basal-bolus insulin regimen  Exclusion Criteria:  History of asthma, chronic obstructive pulmonary disease, or any other clinically important pulmonary disease (e.g., cystic fibrosis, bronchopulmonary dysplasia), use of any medications to treat such conditions within the last year, or significant congenital or acquired cardiopulmonary disease History of serious complications of diabetes (e.g., active proliferative retinopathy or symptomatic autonomic neuropathy) On dialysis Respiratory tract infection within 14 days before screening (subject may return 14 days after resolution of symptoms for rescreening) Treatment with any investigational drug in the past 30 days or an investigational device in the past 2 weeks Any disease other than diabetes or initiation of any new medication that, in the judgment of the Investigator, could have a direct impact on glycemic control during the study Use of antiadrenergic drugs (e.g., beta blockers and clonidine) Any concurrent illness (other than diabetes mellitus) not controlled by a stable therapeutic regimen History of a significant eating disorder (e.g., anorexia or bulimia nervosa) Current drug or alcohol abuse or a history of drug or alcohol abuse that, in the opinion of the Investigator or the Sponsor, would make the subject an unsuitable candidate for participation in the study History of smoking (includes cigarettes, cigars, pipes, vaping devices, and marijuana) in the 6 months before screening Female subject who is pregnant, breastfeeding, intends to become pregnant, or is of child-bearing potential and not using adequate contraceptive methods as required by local regulation or practice (may include sexual abstinence) An event of severe hypoglycemia, as judged by the Investigator, within the 90 days before screening An episode of diabetic ketoacidosis (DKA) requiring hospitalization within the 90 days before screening Exposure to Afrezza in the 30 days before screening