Abstract Background: We compared the pharmacokinetic and pharmacodynamic profiles of insulin aspart, biphasic insulin aspart 70 (BIAsp70) and 50 (BIAsp50) (containing 70% and 50% rapid-acting insulin aspart, respectively), and soluble human insulin under experimental conditions. Subjects and Methods: In this randomized, four-period crossover study, 19 type 1 diabetes patients received subcutaneous injections of identical doses (0.2 U/kg) of insulin aspart, BIAsp70, or BIAsp50 immediately before a standardized meal or human insulin 30 min before meal. Plasma glucose and serum insulin were measured for 12 h postprandially. Results: The pharmacokinetic and pharmacodynamic profiles of human insulin differed from those of insulin aspart, BIAsp70, and BIAsp50. The three different aspart preparations had easily distinguishable features with regard to onset and duration of action. Insulin aspart preparations were, on average, absorbed twice as fast as human insulin. In the initial phases (0-4 h and 0-6 h), the insulin area under the concentration-time curve (AUC(ins)) was significantly higher during insulin aspart treatment compared with the others, whereas insulin aspart had a significantly lower AUC(ins) over the last 6 h (P