Abstract： Background Glycemic control prevents onset and progression of diabetes-related long-term complications.The objective of this study was to demonstrate that twice daily insulin lispro low mix 25 is noninferior to twice daily human insulin mix 30/70 in achieving glycemic control as measured by hemoglobin A1c(HbA1c),from baseline to endpoint,in patients with type 1 or 2 diabetes.Methods In this phase Ⅳ,crossover,open-label,multicenter study,117 Chinese patients with diabetes were randomly assigned to one of two treatment sequence groups.One group received 12-week treatment with twice daily human insulin mix 30/70 followed by 12-week treatment with twice daily insulin lispro low mix 25,while the other group received the reverse treatment sequence.HbA1c,baseline-to-endpoint change in HbA1c,proportion of patients achieving target HbA1c≤7% and≤6.5%,fasting blood glucose,and daily insulin doses were measured for each period.Safety and tolerability were also assessed.Results A statistically significant reduction(P≤0.0001)of HbA1c was achieved after each treatment(human insulin mix 30/70:mean HbA1c=7.91%(95% CI:7.67%,8.15%);insulin lispro low mix 25:mean HbA1c=7.96%(95% CI:7.72%,8.20%)).The 95% CI(-0.20,0.10)of the difference between the two treatments satisfied the prespecified noninferiority margin of 0.3%(lower limit of 95% CI＞-0.3%).No statistically significant differences between treatments were observed for any of the secondary efficacy measures.The incidence of treatment-emergent adverse events and hypoglycemia between the two treatments and treatment sequence groups was similar.Three serious adverse events were reported(human insulin mix 30/70 group:2 patients(1.7%,hypoglycemic coma and cardiac failure);insulin lispro low mix 25 group:1 patient(0.9%,stroke)).All serious adverse events were resolved and no patients died during the study.Conclusion The results support noninferiority of twice daily insulin lispro low mix 25 versus twice daily human insulin mix 30/70 in HbAlc control in Chinese patients with type 1 or 2 diabetes.