OBJECTIVES: The objective of this study was to compare glycaemic control and insulin utilisation in insulin naïve patients with type 2 diabetes (T2D) after initiation on biphasic insulin aspart 30 (BIAsp) or biphasic human insulin 30 (BHI) METHODS: A retrospective cohort study was conducted using the IMS Disease Analyzer a UK primary care database.  Study inclusion required subjects to be insulin naïve with at least one prescription for an oral anti-diabetic agent (proxy for T2D diagnosis), 12 months history and follow up and treatment with either BIAsp or BHI. Patients with a diagnosis of type 1 diabetes were excluded. Glycemic control (HbA1c) was compared at baseline (-6 to 0 months) and at follow-up (+6 to 12 months). Average daily insulin dose (ADD) was compared at follow-up. Effect of age and sex as covariates on the difference in HbA1c and ADD between BIAsp and BHI was controlled for using ANOVA.     RESULTS: Analyses were conducted on 630 BIAsp and 751 BHI patients on whom full data was available. The mean age for BIAsp patients was 61.6 years (59.7% men). For BHI, the mean age was 64.4 (51.9% men). From baseline to follow-up, the mean HbA1c for BIAsp dropped from 9.95% to 8.16% (change= 1.79%) and for BHI the HbA1c dropped from 10.34% to 8.62% (change= 1.72%). The HbA1c difference was borderline significant (p=0.07). The ADD of BIAsp was 46.97 insulin units whereas the BHI ADD was 63.28 IU (p<0.01). CONCLUSIONS: In this large retrospective analysis in insulin naïve patients initiated on pre-mixed insulin there was a trend towards better glycaemic control for users of BIAp compared to BHI. Moreover, BIAsp was associated with a clinically relevant and statistically significantly lower ADD compared to BHI (p<0.01).  This has important implications for patient management and control of UK NHS costs.