We evaluated the effect of glimepiride plus metformin and rosiglitazone plus metformin on glucose, and on cardiovascular risk parameters such as lipoprotein(a) (Lp[a]) and homocysteine (HCT) in patients with type 2 diabetes and metabolic syndrome. Ninety-nine patients in the multicentre, randomized, double-blind study took metformin (1500 mg/day) plus glimepiride (2 mg/day) or rosiglitazone (4 mg/day) for 12 months. Changes in body mass index, glycosylated haemoglobin (HbA1c), Lp(a) and HCT were primary efficacy variables. Fasting plasma glucose (FPG), post-prandial plasma glucose (PPG) and homeostasis model assessment index were also used to assess efficacy. On average, HbA1c decreased by 9.1% and 8.1%, FPG decreased by 7.3% and 10.9%, and PPG decreased by 7.6% and 10.5%, respectively, in the glimepiride and rosiglitazone groups after 12 months. Patients receiving rosiglitazone experienced more rapid improvement in glycaemic control than those on glimepiride, and showed a significant improvement in insulin resistance-related parameters. There was a statistically significant decrease in basal homocysteinaemia in glimepiride-treated patients (-27.3%), but not in rosiglitazone-treated patients. Rosiglitazone plus metformin significantly improved long-term control of insulin resistance-related parameters compared with glimepiride plus metformin, although glimepiride treatment was associated with a slight improvement in cholesterolaemia, not observed in the rosiglitazone-treated patients, and with significant improvements in non-traditional risk factors for cardiovascular disease, such as basal homocysteinaemia and plasma Lp(a) levels.