This is a 24-week randomized double-blind, parallel-group, multi-center, placebo-controlled study of tesaglitazar (0.5 mg and 1 mg) given as add-on therapy to sulphonylurea in patients with type 2 diabetes, not adequately controlled on optimized sulphonylurea treatment and on diet/lifestyle advice during the titration and run-in period. The study comprises a 2-week enrollment period, 6 week placebo metformin titration period, 2-week single-blind run-in period, followed by a 24-week double blind treatment period and a 3-week follow-up period