OBJECTIVE- Because there are limited data on the comparison of insulin aspart and mixed insulin in type 2 diabetes, this trial was performed to compare the efficacy and safety of pre-prandial insulin aspart with human soluble insulin (HI) and human premix (70% NPH/30% regular) insulin (MIX). RESEARCH DESIGN AND METHODS- A total of 231 type 2 diabetic patients were randomized to insulin aspart (n-75), HI (n- 80), or MIX (n=76) for 3 months. Insulin aspart and HI were administered with or without bedtime NPH insulin. A total of 204 patients com-pleted the trial according to protocol. HbA(Ic) 7-point blood glucose, insulin dosage, and hypo-glycemic episodes were recorded. The primary end point was "change of HbA(Ic)" from baseline to last visit. Analysis for equivilence was performed by t tests with three subtests. RESULTS- HbA(Ic) decreased 0.91 +/- 1.00 for insulin aspart, 0.73 +/- 0.87 for HI, and 0.65 +/- 1.10 for MIX with the following confidence intervals: insulin aspart HI (-0.21 to 0.57, P = 0.025), insulin aspart MIX (-0.17 to 0.69, P = 0.092), and HI-MIX (-0.33 to 0.48, P = 0.006). Postprandial blood glucose decreased in the insulin aspart group: 0.44 mmol/l to > 1.67 mmol/l compared with HI and 1.1 mmol/l to > 1.67 mmol/l compared with MIX. Preprandial insulin doses were similar in the insulin aspart and HI groups (10-14.5 U). Hypoglycemic events per month were 0.56 HI, 0.40 insulin aspart, and 0.19 MIX. CONCLUSIONS- Statistically, insulin aspart was not equivalent to another treatment in therms of HbA(Ic) reduction. Insulin aspart treatment resulted in impreoved HbA(Ic) and postprandial blood glucose. The application of insulin aspart was safe and well tolerated.