Background A new inhalable insulin aerosoI(Inh-Ins)was developed in China.The aim of this multicenter clinical study was to evaluate the efficacy and safety of this new Inh-Ins as a treatment of type 2 diabetes.Regular porcine insulin(RI)was used as a control.Methods This study is a prospective,randomized,open-label,parallel-group multicenter clinical trial in which 253 qualified patients with type 2 diabetes received the insulin Glargine daily at bedtime plus either a pre-meal Inh-Ins or a pre-meal subcutaneous RI for 12 weeks.HbA1c,fasting plasma glucose(FPG),the 1-hour-postprandial blood glucose(1hPBG)and the 2-hour-postprandial blood glucose(2hPBG)were measured.Events were monitored for adverse effects.Results After 12 weeks,the HbA1c decreased significantly from baseline in both treatment groups,with no significant difference between the two regimens.In the Inh-Ins group,FPG,both 1hPBG and 2hPBG significantly declined from baseline after the 8th-and 12th-weeks of treatment.The reduced values of FPG or 1hPBG between the two groups showed a more significant hypoglycemic effect with the Inh-Ins than the RI.After 12 weeks,the pulmonary carbon monoxide diffusing capacity(DLco)was significantly lower in Inh-Ins group than in the RI.The main side effects of Inh-Ins were coughing,excessive sputum,and hypoglycemia.Conclusions Inh-Ins was effective in decreasing HbA1c like the RI.It was better in lowering the FPG and the 1hPBG than the RI.Its main side effects were coughing,excessive sputum,and hypoglycemia.Also,Inh-Ins slightly impaired DLco.