A variety of abnormalities of metabolic, haemostatic and endothelial markers are associated with Type 2 diabetes. Evidence suggests that poor post-prandial blood glucose control may contribute to vascular risk. We aimed to examine whether the restoration of a more physiological insulin profile post-prandially would improve these abnormalities. Twenty-one patients with insulin-treated Type 2 diabetes were recruited into a single centre, crossover, double-blind study. Patients were randomized to unmodified human insulin or insulin aspart before main meals for 6-week study periods, both together with NPH insulin. At the end of each study period, pre-breakfast levels of markers of vascular risk were assessed and a test meal performed. There was no significant difference in HbA(1c) (7.04 +/- 0.13% (+/-S.E.) versus 7.15 +/- 0.11%, P = 0.060) with insulin aspart compared to human insulin at the end of each study period. The mean post-prandial blood glucose concentration at 90 min from self-monitored results was lower with insulin aspart than with human insulin (7.9 +/- 0.4 mmol/l versus 9.3 +/- 0.4 mmol/l, P = 0.011) as was study day post-prandial blood glucose at 90 min (8.4 +/- 0.5 mmol/l versus 9.2 +/- 0.6 mmol/l, P = 0.046). No significant differences were found in fasting lipid profile, apolipoproteins, fibrinogen, plasminogen activator inhibitor-1, E-selectin, or homocysteine between the two study periods. Insulin aspart resulted in improved post-prandial glycaemic control when compared to human insulin in Type 2 diabetic patients, but this was not associated with changes in markers of vascular risk.